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Berndt N, Eckstein J, Wallach I, Nordmeyer S, Kelm M, Kirchner M, Goubergrits L, Schafstedde M, Hennemuth A, Kraus M, Grune T, Mertins P, Kuehne T, Holzhütter HG. CARDIOKIN1: Computational Assessment of Myocardial Metabolic Capability in Healthy Controls and Patients With Valve Diseases. Circulation 2021; 144:1926-1939. [PMID: 34762513 PMCID: PMC8663543 DOI: 10.1161/circulationaha.121.055646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Supplemental Digital Content is available in the text. Background: Many heart diseases can result in reduced pumping capacity of the heart muscle. A mismatch between ATP demand and ATP production of cardiomyocytes is one of the possible causes. Assessment of the relation between myocardial ATP production (MVATP) and cardiac workload is important for better understanding disease development and choice of nutritional or pharmacologic treatment strategies. Because there is no method for measuring MVATP in vivo, the use of physiology-based metabolic models in conjunction with protein abundance data is an attractive approach. METHOD: We developed a comprehensive kinetic model of cardiac energy metabolism (CARDIOKIN1) that recapitulates numerous experimental findings on cardiac metabolism obtained with isolated cardiomyocytes, perfused animal hearts, and in vivo studies with humans. We used the model to assess the energy status of the left ventricle of healthy participants and patients with aortic stenosis and mitral valve insufficiency. Maximal enzyme activities were individually scaled by means of protein abundances in left ventricle tissue samples. The energy status of the left ventricle was quantified by the ATP consumption at rest (MVATP[rest]), at maximal workload (MVATP[max]), and by the myocardial ATP production reserve, representing the span between MVATP(rest) and MVATP(max). Results: Compared with controls, in both groups of patients, MVATP(rest) was increased and MVATP(max) was decreased, resulting in a decreased myocardial ATP production reserve, although all patients had preserved ejection fraction. The variance of the energetic status was high, ranging from decreased to normal values. In both patient groups, the energetic status was tightly associated with mechanic energy demand. A decrease of MVATP(max) was associated with a decrease of the cardiac output, indicating that cardiac functionality and energetic performance of the ventricle are closely coupled. Conclusions: Our analysis suggests that the ATP-producing capacity of the left ventricle of patients with valvular dysfunction is generally diminished and correlates positively with mechanical energy demand and cardiac output. However, large differences exist in the energetic state of the myocardium even in patients with similar clinical or image-based markers of hypertrophy and pump function. Registration: URL: https://www.clinicaltrials.gov; Unique identifiers: NCT03172338 and NCT04068740.
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Affiliation(s)
- Nikolaus Berndt
- Institute of Computer-assisted Cardiovascular Medicine, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Johannes Eckstein
- Institute of Computer-assisted Cardiovascular Medicine, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Institute of Biochemistry, Charitá - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Iwona Wallach
- Institute of Computer-assisted Cardiovascular Medicine, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Institute of Biochemistry, Charitá - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Sarah Nordmeyer
- Institute of Computer-assisted Cardiovascular Medicine, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Department of Congenital Heart Disease - Pediatric Cardiology, Deutsches Herzzentrum Berlin (DHZB), Berlin, Germany
| | - Marcus Kelm
- Institute of Computer-assisted Cardiovascular Medicine, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Department of Congenital Heart Disease - Pediatric Cardiology, Deutsches Herzzentrum Berlin (DHZB), Berlin, Germany; Deutsches Zentrum für Herz-Kreislauf-Forschung e. V. (DZHK), Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany
| | - Marieluise Kirchner
- Berlin Institute of Health (BIH), Berlin, Germany; Proteomics Platform, Max Delbrück Center for Molecular Medicine (MDC), Berlin, Germany
| | - Leonid Goubergrits
- Institute of Computer-assisted Cardiovascular Medicine, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Einstein Center Digital Future, Berlin, Germany
| | - Marie Schafstedde
- Institute of Computer-assisted Cardiovascular Medicine, Charité; Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Department of Congenital Heart Disease - Pediatric Cardiology, Deutsches Herzzentrum Berlin (DHZB), Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany
| | - Anja Hennemuth
- Institute of Computer-assisted Cardiovascular Medicine, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Milena Kraus
- Digital Health Center, Hasso Plattner Institute, University of Potsdam, Germany
| | - Tilman Grune
- Deutsches Zentrum für Herz-Kreislauf-Forschung e. V. (DZHK), Berlin, Germany; Department of Molecular Toxicology, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), Nuthetal, Germany
| | - Philipp Mertins
- Berlin Institute of Health (BIH), Berlin, Germany; Proteomics Platform, Max Delbrück Center for Molecular Medicine (MDC), Berlin, Germany
| | - Titus Kuehne
- Institute of Computer-assisted Cardiovascular Medicine, Charité; Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Department of Congenital Heart Disease - Pediatric Cardiology, Deutsches Herzzentrum Berlin (DHZB), Berlin, Germany; Deutsches Zentrum für Herz-Kreislauf-Forschung e. V. (DZHK), Berlin, Germany
| | - Hermann-Georg Holzhütter
- Institute of Biochemistry, Charitá - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
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Berndt N, Kovács R, Schoknecht K, Rösner J, Reiffurth C, Maechler M, Holzhütter HG, Dreier JP, Spies C, Liotta A. Low neuronal metabolism during isoflurane-induced burst suppression is related to synaptic inhibition while neurovascular coupling and mitochondrial function remain intact. J Cereb Blood Flow Metab 2021; 41:2640-2655. [PMID: 33899556 PMCID: PMC8504408 DOI: 10.1177/0271678x211010353] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Deep anaesthesia may impair neuronal, vascular and mitochondrial function facilitating neurological complications, such as delirium and stroke. On the other hand, deep anaesthesia is performed for neuroprotection in critical brain diseases such as status epilepticus or traumatic brain injury. Since the commonly used anaesthetic propofol causes mitochondrial dysfunction, we investigated the impact of the alternative anaesthetic isoflurane on neuro-metabolism. In deeply anaesthetised Wistar rats (burst suppression pattern), we measured increased cortical tissue oxygen pressure (ptiO2), a ∼35% drop in regional cerebral blood flow (rCBF) and burst-associated neurovascular responses. In vitro, 3% isoflurane blocked synaptic transmission and impaired network oscillations, thereby decreasing the cerebral metabolic rate of oxygen (CMRO2). Concerning mitochondrial function, isoflurane induced a reductive shift in flavin adenine dinucleotide (FAD) and decreased stimulus-induced FAD transients as Ca2+ influx was reduced by ∼50%. Computer simulations based on experimental results predicted no direct effects of isoflurane on mitochondrial complexes or ATP-synthesis. We found that isoflurane-induced burst suppression is related to decreased ATP consumption due to inhibition of synaptic activity while neurovascular coupling and mitochondrial function remain intact. The neurometabolic profile of isoflurane thus appears to be superior to that of propofol which has been shown to impair the mitochondrial respiratory chain.
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Affiliation(s)
- Nikolaus Berndt
- Institute for Imaging Science and Computational Modelling in Cardiovascular Medicine Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Richard Kovács
- Institute for Neurophysiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Karl Schoknecht
- Carl-Ludwig-Institute for Physiology, University Leipzig, Leipzig, Germany
| | - Jörg Rösner
- Neuroscience Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Clemens Reiffurth
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Mathilde Maechler
- Institute for Neurophysiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Hermann-Georg Holzhütter
- Institute of Biochemistry, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Jens P Dreier
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Bernstein center for Computational Neuroscience, Charité - Universitätsmedizin, Humboldt-Universität zu Berlin and Technische Universität Berlin, Berlin, Germany.,Einstein Center for Neuroscience, Charité - Universitätsmedizin Berlin, the Freie Universität Berlin, the Humboldt-Universität zu Berlin and the Technische Universität Berlin, Berlin, Germany
| | - Claudia Spies
- Department of Anesthesiology and Intensive Care, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany.,Berlin Institute of Health, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Agustin Liotta
- Institute for Neurophysiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany.,Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Department of Anesthesiology and Intensive Care, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany.,Berlin Institute of Health, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
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3
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Garczyńska K, Tzschätzsch H, Assili S, Kühl AA, Häckel A, Schellenberger E, Berndt N, Holzhütter HG, Braun J, Sack I, Guo J. Effect of Post-mortem Interval and Perfusion on the Biophysical Properties of ex vivo Liver Tissue Investigated Longitudinally by MRE and DWI. Front Physiol 2021; 12:696304. [PMID: 34413787 PMCID: PMC8369239 DOI: 10.3389/fphys.2021.696304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 07/12/2021] [Indexed: 11/21/2022] Open
Abstract
Structural changes of soft tissues on the cellular level can be characterized by histopathology, but not longitudinally in the same tissue. Alterations of cellular structures and tissue matrix are associated with changes in biophysical properties which can be monitored longitudinally by quantitative diffusion-weighted imaging (DWI) and magnetic resonance elastography (MRE). In this work, DWI and MRE examinations were performed in a 0.5-Tesla compact scanner to investigate longitudinal changes in water diffusivity, stiffness and viscosity of ex-vivo rat livers for up to 20 h post-mortem (pm). The effect of blood on biophysical parameters was examined in 13 non-perfused livers (containing blood, NPLs) and 14 perfused livers (blood washed out, PLs). Changes in cell shape, cell packing and cell wall integrity were characterized histologically. In all acquisitions, NPLs presented with higher shear-wave speed (c), higher shear-wave penetration rate (a) and smaller apparent-diffusion-coefficients (ADCs) than PL. Time-resolved analysis revealed three distinct phases: (i) an initial phase (up to 2 h pm) with markedly increased c and a and reduced ADCs; (ii) an extended phase with relatively stable values; and (iii) a degradation phase characterized by significant increases in a (10 h pm in NPLs and PLs) and ADCs (10 h pm in NPLs, 13 h pm in PLs). Histology revealed changes in cell shape and packing along with decreased cell wall integrity, indicating tissue degradation in NPLs and PLs 10 h pm. Taken together, our results demonstrate that the biophysical properties of fresh liver tissue rapidly change within 2 h pm, which seems to be an effect of both cytotoxic edema and vascular blood content. Several hours later, disruption of cell walls resulted in higher water diffusivity and wave penetration. These results reveal the individual contributions of vascular components and cellular integrity to liver elastography and provide a biophysical, imaging-based fingerprint of liver tissue degradation.
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Affiliation(s)
- Karolina Garczyńska
- Department of Radiology, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Veterinary Pathology, College of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Heiko Tzschätzsch
- Department of Radiology, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Sanam Assili
- Department of Radiology, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Biology, SUNY Albany, Albany, NY, United States
| | - Anja A. Kühl
- iPATH.Berlin - Core Unit of Charité, Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Akvile Häckel
- Department of Radiology, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Eyk Schellenberger
- Department of Radiology, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Nikolaus Berndt
- Institute for Imaging Science and Computational Modelling in Cardiovascular Medicine, Berlin Institute of Health (BIH), Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Computational Systems Biochemistry Group, Institute of Biochemistry, Berlin Institute of Health (BIH), Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Hermann-Georg Holzhütter
- Computational Systems Biochemistry Group, Institute of Biochemistry, Berlin Institute of Health (BIH), Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Jürgen Braun
- Institute of Medical Informatics, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Ingolf Sack
- Department of Radiology, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Jing Guo
- Department of Radiology, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
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4
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Willimsky G, Beier C, Immisch L, Papafotiou G, Scheuplein V, Goede A, Holzhütter HG, Blankenstein T, Kloetzel PM. In vitro proteasome processing of neo-splicetopes does not predict their presentation in vivo. eLife 2021; 10:e62019. [PMID: 33875134 PMCID: PMC8154032 DOI: 10.7554/elife.62019] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 04/15/2021] [Indexed: 12/25/2022] Open
Abstract
Proteasome-catalyzed peptide splicing (PCPS) of cancer-driving antigens could generate attractive neoepitopes to be targeted by T cell receptor (TCR)-based adoptive T cell therapy. Based on a spliced peptide prediction algorithm, TCRs were generated against putative KRASG12V- and RAC2P29L-derived neo-splicetopes with high HLA-A*02:01 binding affinity. TCRs generated in mice with a diverse human TCR repertoire specifically recognized the respective target peptides with high efficacy. However, we failed to detect any neo-splicetope-specific T cell response when testing the in vivo neo-splicetope generation and obtained no experimental evidence that the putative KRASG12V- and RAC2P29L-derived neo-splicetopes were naturally processed and presented. Furthermore, only the putative RAC2P29L-derived neo-splicetopes was generated by in vitro PCPS. The experiments pose severe questions on the notion that available algorithms or the in vitro PCPS reaction reliably simulate in vivo splicing and argue against the general applicability of an algorithm-driven 'reverse immunology' pipeline for the identification of cancer-specific neo-splicetopes.
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MESH Headings
- Animals
- Antigen Presentation
- Antigens, Neoplasm/genetics
- Antigens, Neoplasm/immunology
- Antigens, Neoplasm/metabolism
- CD8-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/metabolism
- Epitopes
- HEK293 Cells
- HLA-A2 Antigen/immunology
- HLA-A2 Antigen/metabolism
- Humans
- K562 Cells
- Mice
- Mice, Transgenic
- Mutation
- Neoplasms/genetics
- Neoplasms/immunology
- Neoplasms/metabolism
- Proof of Concept Study
- Proteasome Endopeptidase Complex/metabolism
- Protein Processing, Post-Translational
- Proto-Oncogene Proteins p21(ras)/genetics
- Proto-Oncogene Proteins p21(ras)/immunology
- Proto-Oncogene Proteins p21(ras)/metabolism
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/immunology
- Receptors, Antigen, T-Cell/metabolism
- rac GTP-Binding Proteins/genetics
- rac GTP-Binding Proteins/immunology
- rac GTP-Binding Proteins/metabolism
- RAC2 GTP-Binding Protein
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Affiliation(s)
- Gerald Willimsky
- Institute of Immunology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- German Cancer Research Center, Heidelberg, Germany
- German Cancer Consortium, partner site Berlin, Berlin, Germany
| | - Christin Beier
- Institute of Biochemistry, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Lena Immisch
- Institute of Immunology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- German Cancer Research Center, Heidelberg, Germany
- German Cancer Consortium, partner site Berlin, Berlin, Germany
- Humboldt-Universität zu Berlin, Berlin, Germany
| | - George Papafotiou
- Institute of Immunology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- German Cancer Research Center, Heidelberg, Germany
- German Cancer Consortium, partner site Berlin, Berlin, Germany
| | - Vivian Scheuplein
- Max Delbrück Center for Molecular Medicine in Helmholtz Association, Berlin, Germany
| | - Andrean Goede
- Institute of Physiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Hermann-Georg Holzhütter
- Institute of Biochemistry, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Thomas Blankenstein
- Institute of Immunology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- Max Delbrück Center for Molecular Medicine in Helmholtz Association, Berlin, Germany
- Berlin Institute of Health, Berlin, Germany
| | - Peter M Kloetzel
- Institute of Biochemistry, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
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5
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Hudert CA, Tzschätzsch H, Rudolph B, Loddenkemper C, Holzhütter HG, Kalveram L, Wiegand S, Braun J, Sack I, Guo J. How histopathologic changes in pediatric nonalcoholic fatty liver disease influence in vivo liver stiffness. Acta Biomater 2021; 123:178-186. [PMID: 33472102 DOI: 10.1016/j.actbio.2021.01.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/14/2020] [Accepted: 01/11/2021] [Indexed: 02/06/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in children and adolescents. About 30% of patients with NAFLD progress to the more severe condition of nonalcoholic steatohepatitis (NASH), which is typically diagnosed using liver biopsy. Liver stiffness (LS) quantified by elastography is a promising imaging marker for the noninvasive assessment of NAFLD and NASH in pediatric patients. However, the link between LS and specific histopathologic features used for clinical staging of NAFLD is not well defined. Furthermore, LS data reported in the literature can vary greatly due to the use of different measurement techniques. Uniquely, time-harmonic elastography (THE) based on ultrasound and magnetic resonance elastography (MRE) use the same mechanical stimulation, allowing us to compare LS in biopsy-proven NAFLD previously determined by THE and MRE in 67 and 50 adolescents, respectively. In the present work, we analyzed the influence of seven distinct histopathologic features on LS, including septal infiltration, bridging fibrosis, pericellular fibrosis, hepatocellular ballooning, portal inflammation, lobular inflammation, and steatosis. LS was highly correlated with periportal and lobular fibrosis as well as hepatocellular ballooning while no independent association was found for inflammation and steatosis. Based on this analysis, we propose a composite elastography score (CES) which includes the four key histopathologic features identified as mechanically relevant. Interestingly, CES-relevant histopathologic features were associated with zonal distribution patterns of pediatric NAFLD. Mechano-structural changes associated with NAFLD progression can be histopathologically staged using the CES, which is easily determined noninvasively based on LS measured by time-harmonic elastography.
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6
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Holzhütter HG, Berndt N. Computational Hypothesis: How Intra-Hepatic Functional Heterogeneity May Influence the Cascading Progression of Free Fatty Acid-Induced Non-Alcoholic Fatty Liver Disease (NAFLD). Cells 2021; 10:cells10030578. [PMID: 33808045 PMCID: PMC7999144 DOI: 10.3390/cells10030578] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/01/2021] [Accepted: 03/02/2021] [Indexed: 02/06/2023] Open
Abstract
Non-Alcoholic Fatty Liver Disease (NAFLD) is the most common type of chronic liver disease in developed nations, affecting around 25% of the population. Elucidating the factors causing NAFLD in individual patients to progress in different rates and to different degrees of severity, is a matter of active medical research. Here, we aim to provide evidence that the intra-hepatic heterogeneity of rheological, metabolic and tissue-regenerating capacities plays a central role in disease progression. We developed a generic mathematical model that constitutes the liver as ensemble of small liver units differing in their capacities to metabolize potentially cytotoxic free fatty acids (FFAs) and to repair FFA-induced cell damage. Transition from simple steatosis to more severe forms of NAFLD is described as self-amplifying process of cascading liver failure, which, to stop, depends essentially on the distribution of functional capacities across the liver. Model simulations provided the following insights: (1) A persistently high plasma level of FFAs is sufficient to drive the liver through different stages of NAFLD; (2) Presence of NAFLD amplifies the deleterious impact of additional tissue-damaging hits; and (3) Coexistence of non-steatotic and highly steatotic regions is indicative for the later occurrence of severe NAFLD stages.
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Affiliation(s)
- Hermann-Georg Holzhütter
- Institute of Biochemistry, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, Germany
- Correspondence:
| | - Nikolaus Berndt
- Institute for Imaging Science and Computational Modelling in Cardiovascular Medicine, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Augustenburger Platz 1, 13353 Berlin, Germany;
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7
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Berndt N, Kolbe E, Gajowski R, Eckstein J, Ott F, Meierhofer D, Holzhütter HG, Matz-Soja M. Functional Consequences of Metabolic Zonation in Murine Livers: Insights for an Old Story. Hepatology 2021; 73:795-810. [PMID: 32286709 DOI: 10.1002/hep.31274] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 03/13/2020] [Accepted: 04/01/2020] [Indexed: 12/19/2022]
Abstract
BACKGROUND AND AIMS Zone-dependent differences in expression of metabolic enzymes along the portocentral axis of the acinus are a long-known feature of liver metabolism. A prominent example is the preferential localization of the enzyme, glutamine synthetase, in pericentral hepatocytes, where it converts potentially toxic ammonia to the valuable amino acid, glutamine. However, with the exception of a few key regulatory enzymes, a comprehensive and quantitative assessment of zonal differences in the abundance of metabolic enzymes and, much more important, an estimation of the associated functional differences between portal and central hepatocytes is missing thus far. APPROACH AND RESULTS We addressed this problem by establishing a method for the separation of periportal and pericentral hepatocytes that yields sufficiently pure fractions of both cell populations. Quantitative shotgun proteomics identified hundreds of differentially expressed enzymes in the two cell populations. We used zone-specific proteomics data for scaling of the maximal activities to generate portal and central instantiations of a comprehensive kinetic model of central hepatic metabolism (Hepatokin1). CONCLUSIONS The model simulations revealed significant portal-to-central differences in almost all metabolic pathways involving carbohydrates, fatty acids, amino acids, and detoxification.
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Affiliation(s)
- Nikolaus Berndt
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität BerlinHumboldt-Universität zu Berlin, and Berlin Institute of HealthInstitute for Imaging Science and Computational Modelling in Cardiovascular MedicineBerlinGermany
| | - Erik Kolbe
- Rudolf-Schönheimer-Institute of BiochemistryFaculty of MedicineLeipzig UniversityLeipzigGermany
| | - Robert Gajowski
- Max Planck Institute for Molecular GeneticsBerlinGermany.,Department of Biology, Chemistry, PharmacyFreie UniversitätBerlinGermany
| | - Johannes Eckstein
- Charité -Universitätsmedizin Berlin, corporate member of Freie Universität BerlinHumboldt-Universität zu Berlin, and Berlin Institute of HealthInstitute of BiochemistryBerlinGermany
| | - Fritzi Ott
- Rudolf-Schönheimer-Institute of BiochemistryFaculty of MedicineLeipzig UniversityLeipzigGermany
| | | | - Hermann-Georg Holzhütter
- Charité -Universitätsmedizin Berlin, corporate member of Freie Universität BerlinHumboldt-Universität zu Berlin, and Berlin Institute of HealthInstitute of BiochemistryBerlinGermany
| | - Madlen Matz-Soja
- Rudolf-Schönheimer-Institute of BiochemistryFaculty of MedicineLeipzig UniversityLeipzigGermany.,Division of Hepatology, Department of Oncology, Gastroenterology, Hepatology, Pulmonology, and Infectious DiseasesLeipzig University Medical CenterLeipzigGermany
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8
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Kalveram L, Schunck WH, Rothe M, Rudolph B, Loddenkemper C, Holzhütter HG, Henning S, Bufler P, Schulz M, Meierhofer D, Zhang IW, Weylandt KH, Wiegand S, Hudert CA. Regulation of the cytochrome P450 epoxyeicosanoid pathway is associated with distinct histologic features in pediatric non-alcoholic fatty liver disease. Prostaglandins Leukot Essent Fatty Acids 2021; 164:102229. [PMID: 33388475 DOI: 10.1016/j.plefa.2020.102229] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 12/15/2020] [Accepted: 12/15/2020] [Indexed: 12/14/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a significant health burden in obese children for which there is currently no specific therapy. Preclinical studies indicate that epoxyeicosanoids, a class of bioactive lipid mediators that are generated by cytochrome P450 (CYP) epoxygenases and inactivated by the soluble epoxide hydrolase (sEH), play a protective role in NAFLD. We performed a comprehensive lipidomics analysis using liver tissue and blood samples of 40 children with NAFLD. Proteomics was performed to determine CYP epoxygenase and sEH expressions. Hepatic epoxyeicosanoids significantly increased with higher grades of steatosis, while their precursor PUFAs were unaltered. Concomitantly, total CYP epoxygenase activity increased while protein level and activity of sEH decreased. In contrast, hepatic epoxyeicosanoids showed a strong decreasing trend with higher stages of fibrosis, accompanied by a decrease of CYP epoxygenase activity and protein expression. These findings suggest that the CYP epoxygenase/sEH pathway represents a potential pharmacologic target for the treatment of NAFLD.
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Affiliation(s)
- Laura Kalveram
- Center for Chronically Sick Children, Charité - Universitätsmedizin Berlin, 13353 Berlin, Germany
| | | | | | - Birgit Rudolph
- Institute of Pathology, Charité - Universitätsmedizin Berlin, 10117 Berlin, Germany
| | | | | | - Stephan Henning
- Department of Pediatric Gastroenterology, Nephrology and Metabolic Diseases, Charité -Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Philip Bufler
- Department of Pediatric Gastroenterology, Nephrology and Metabolic Diseases, Charité -Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Marten Schulz
- Department of Hepatology and Gastroenterology, Charité - Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - David Meierhofer
- Max Planck Institute for Molecular Genetics, Mass Spectrometry Facility, 14195 Berlin, Germany
| | - Ingrid W Zhang
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Karsten H Weylandt
- Department of Gastroenterology, Diabetes, Oncology and Rheumatology, Ruppiner Kliniken, Brandenburg Medical School, 16816 Neuruppin, Germany
| | - Susanna Wiegand
- Center for Chronically Sick Children, Charité - Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Christian A Hudert
- Department of Pediatric Gastroenterology, Nephrology and Metabolic Diseases, Charité -Universitätsmedizin Berlin, 13353 Berlin, Germany.
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9
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Garczyńska K, Tzschätzsch H, Kühl AA, Morr AS, Lilaj L, Häckel A, Schellenberger E, Berndt N, Holzhütter HG, Braun J, Sack I, Guo J. Changes in Liver Mechanical Properties and Water Diffusivity During Normal Pregnancy Are Driven by Cellular Hypertrophy. Front Physiol 2020; 11:605205. [PMID: 33329058 PMCID: PMC7719759 DOI: 10.3389/fphys.2020.605205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 10/29/2020] [Indexed: 12/27/2022] Open
Abstract
During pregnancy, the body’s hyperestrogenic state alters hepatic metabolism and synthesis. While biochemical changes related to liver function during normal pregnancy are well understood, pregnancy-associated alterations in biophysical properties of the liver remain elusive. In this study, we investigated 26 ex vivo fresh liver specimens harvested from pregnant and non-pregnant rats by diffusion-weighted imaging (DWI) and magnetic resonance elastography (MRE) in a 0.5-Tesla compact magnetic resonance imaging (MRI) scanner. Water diffusivity and viscoelastic parameters were compared with histological data and blood markers. We found livers from pregnant rats to have (i) significantly enlarged hepatocytes (26 ± 15%, p < 0.001), (ii) increased liver stiffness (12 ± 15%, p = 0.012), (iii) decreased viscosity (−23 ± 14%, p < 0.001), and (iv) increased water diffusivity (12 ± 11%, p < 0.001). In conclusion, increased stiffness and reduced viscosity of the liver during pregnancy are mainly attributable to hepatocyte enlargement. Hypertrophy of liver cells imposes fewer restrictions on intracellular water mobility, resulting in a higher hepatic water diffusion coefficient. Collectively, MRE and DWI have the potential to inform on structural liver changes associated with pregnancy in a clinical context.
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Affiliation(s)
- Karolina Garczyńska
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Heiko Tzschätzsch
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Anja A Kühl
- iPATH.Berlin Core Unit, Charitá - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Anna Sophie Morr
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Ledia Lilaj
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Akvile Häckel
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Eyk Schellenberger
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Nikolaus Berndt
- Institute for Imaging Science and Computational Modelling in Cardiovascular Medicine, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Computational Systems Biochemistry Group, Institute of Biochemistry, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Hermann-Georg Holzhütter
- Computational Systems Biochemistry Group, Institute of Biochemistry, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Jürgen Braun
- Institute of Medical Informatics, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Ingolf Sack
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Jing Guo
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
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10
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Berndt N, Eckstein J, Heucke N, Wuensch T, Gajowski R, Stockmann M, Meierhofer D, Holzhütter HG. Metabolic heterogeneity of human hepatocellular carcinoma: implications for personalized pharmacological treatment. FEBS J 2020; 288:2332-2346. [PMID: 33030799 DOI: 10.1111/febs.15587] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 09/01/2020] [Accepted: 10/05/2020] [Indexed: 12/14/2022]
Abstract
Metabolic reprogramming is a characteristic feature of cancer cells, but there is no unique metabolic program for all tumors. Genetic and gene expression studies have revealed heterogeneous inter- and intratumor patterns of metabolic enzymes and membrane transporters. The functional implications of this heterogeneity remain often elusive. Here, we applied a systems biology approach to gain a comprehensive and quantitative picture of metabolic changes in individual hepatocellular carcinoma (HCC). We used protein intensity profiles determined by mass spectrometry in samples of 10 human HCCs and the adjacent noncancerous tissue to calibrate Hepatokin1, a complex mathematical model of liver metabolism. We computed the 24-h profile of 18 metabolic functions related to carbohydrate, lipid, and nitrogen metabolism. There was a general tendency among the tumors toward downregulated glucose uptake and glucose release albeit with large intertumor variability. This finding calls into question that the Warburg effect dictates the metabolic phenotype of HCC. All tumors comprised elevated β-oxidation rates. Urea synthesis was found to be consistently downregulated but without compromising the tumor's capacity for ammonia detoxification owing to increased glutamine synthesis. The largest intertumor heterogeneity was found for the uptake and release of lactate and the size of the cellular glycogen content. In line with the observed metabolic heterogeneity, the individual HCCs differed largely in their vulnerability against pharmacological treatment with metformin. Taken together, our approach provided a comprehensive and quantitative characterization of HCC metabolism that may pave the way for a computational a priori assessment of pharmacological therapies targeting metabolic processes of HCC.
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Affiliation(s)
- Nikolaus Berndt
- Institute for Imaging Science and Computational Modelling in Cardiovascular Medicine, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany
| | - Johannes Eckstein
- Institute of Biochemistry, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany
| | - Niklas Heucke
- Department of Surgery, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany
| | - Tilo Wuensch
- Department of Surgery, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany
| | - Robert Gajowski
- Mass Spectroscopy Facility, Max Planck Institute for Molecular Genetics, Berlin, Germany.,Department of Biology, Chemistry, and Pharmacy, Freie Universität Berlin, Germany
| | - Martin Stockmann
- Department of Surgery, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany
| | - David Meierhofer
- Mass Spectroscopy Facility, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Hermann-Georg Holzhütter
- Institute of Biochemistry, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany
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11
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Brosig A, Fuchs J, Ipek F, Kroon C, Schrötter S, Vadhvani M, Polyzou A, Ledderose J, van Diepen M, Holzhütter HG, Trimbuch T, Gimber N, Schmoranzer J, Lieberam I, Rosenmund C, Spahn C, Scheerer P, Szczepek M, Leondaritis G, Eickholt BJ. The Axonal Membrane Protein PRG2 Inhibits PTEN and Directs Growth to Branches. Cell Rep 2020; 29:2028-2040.e8. [PMID: 31722215 PMCID: PMC6856728 DOI: 10.1016/j.celrep.2019.10.039] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 08/09/2019] [Accepted: 10/09/2019] [Indexed: 01/03/2023] Open
Abstract
In developing neurons, phosphoinositide 3-kinases (PI3Ks) control axon growth and branching by positively regulating PI3K/PI(3,4,5)P3, but how neurons are able to generate sufficient PI(3,4,5)P3 in the presence of high levels of the antagonizing phosphatase PTEN is difficult to reconcile. We find that normal axon morphogenesis involves homeostasis of elongation and branch growth controlled by accumulation of PI(3,4,5)P3 through PTEN inhibition. We identify a plasma membrane-localized protein-protein interaction of PTEN with plasticity-related gene 2 (PRG2). PRG2 stabilizes membrane PI(3,4,5)P3 by inhibiting PTEN and localizes in nanoclusters along axon membranes when neurons initiate their complex branching behavior. We demonstrate that PRG2 is both sufficient and necessary to account for the ability of neurons to generate axon filopodia and branches in dependence on PI3K/PI(3,4,5)P3 and PTEN. Our data indicate that PRG2 is part of a neuronal growth program that induces collateral branch growth in axons by conferring local inhibition of PTEN. Neuronal axon growth and branching is globally regulated by PI3K/PTEN signaling PRG2 inhibits PTEN and stabilizes PIP3 and F-actin PRG2 localizes to nanoclusters on the axonal membrane and coincides with branching PRG2 promotes axonal filopodia and branching dependent on PI3K/PTEN
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Affiliation(s)
- Annika Brosig
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Joachim Fuchs
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Fatih Ipek
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Cristina Kroon
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Sandra Schrötter
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; Department of Genetics and Complex Diseases, T.H. Chan Harvard School of Public Health, Boston, MA 02120, USA
| | - Mayur Vadhvani
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Alexandra Polyzou
- Department of Pharmacology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece
| | - Julia Ledderose
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Michiel van Diepen
- Institute of Infectious Disease and Molecular Medicine, Faculty of Health Science, University of Cape Town, Cape Town, South Africa
| | - Hermann-Georg Holzhütter
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Thorsten Trimbuch
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Niclas Gimber
- Advanced Medical Bioimaging Core Facility (AMBIO), Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Jan Schmoranzer
- Advanced Medical Bioimaging Core Facility (AMBIO), Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Ivo Lieberam
- Centre for Stem Cells and Regenerative Medicine and Centre for Developmental Neurobiology, MRC Centre for Neurodevelopmental Disorders, King's College, London, UK
| | - Christian Rosenmund
- NeuroCure-Cluster of Excellence, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Christian Spahn
- NeuroCure-Cluster of Excellence, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; Institute of Medical Physics and Biophysics, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Patrick Scheerer
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Michal Szczepek
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - George Leondaritis
- Department of Pharmacology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece.
| | - Britta J Eickholt
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; NeuroCure-Cluster of Excellence, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
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12
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Holzhütter HG, Archer G, Dami N, Lovell DP, Saltelli A, Sjöström M. Recommendations for the Application of Biostatistical Methods during the Development and Validation of Alternative Toxicological Methods. Altern Lab Anim 2020. [DOI: 10.1177/026119299602400410] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Assessment of the relevance and reliability of alternative toxicological methods requires the application of biostatistical methods. This report contains the recommendations of the ECVAM Task Force on Biostatistics for the appropriate use of biometrical methods, and for closer collaboration between biostatisticians and experimental toxicologists in the development and validation of alternative methods. The main objectives of these recommendations are to improve the compatibility of the results obtained from different studies, and to prevent the misinterpretation of statistical analyses. The following points are discussed: a) the general importance of biostatistics in the development and validation of alternative tests; b) optimisation of study designs; c) statistical characterisation and processing of toxicological data; and d) the analysis of relationships which may exist between data obtained from various tests. In particular, the establishment of appropriate prediction models which are able to predict the toxic effects likely to occur in vivo from the results obtained in an in vitro test system is discussed. The members of the Task Force hope that this report will help to stimulate discussions among biostatisticians and experimental toxicologists about how the proper application of biostatistical methods can improve the design and evaluation of alternative toxicological methods.
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Affiliation(s)
- Hermann-Georg Holzhütter
- Humboldt-Universität zu Berlin, Bereich Medizin (Charité), Institut für Biochemie, Hessische Str. 3–4, 10115 Berlin, Germany
| | - Graeme Archer
- ECVAM, JRC Environment Institute, 21020 Ispra (Va), Italy
| | - Nadia Dami
- L'Oréal, Recherche Avancée, 1 Avenue Eugène Schueller, 93601 Aulnay-sous-Bois, France
| | - David P. Lovell
- BIBRA International, Woodmansterne Road, Carshalton, Surrey SMS 4DS, UK
| | - Andrea Saltelli
- Atmospheric Chemistry Unit, JRC Environment Institute, 21020 Ispra (Va), Italy
| | - Michael Sjöström
- Organic Chemistry, Research Group for Chemometrics, Umeå University, 901 87 Umeå, Sweden
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13
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Spielmann H, Balls M, Dupuis J, Pape WJW, de Silva O, Holzhütter HG, Gerberick F, Liebsch M, Lovell WW, Pfannenbecker U. A Study on UV Filter Chemicals from Annex VII of European Union Directive 76/768/EEC, in the In Vitro 3T3 NRU Phototoxicity Test. Altern Lab Anim 2020. [DOI: 10.1177/026119299802600511] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In 1996, the Scientific Committee on Cosmetology of DGXXIV of the European Commission asked the European Centre for the Validation of Alternative Methods to test eight UV filter chemicals from the 1995 edition of Annex VII of Directive 76/768/EEC in a blind trial in the in vitro 3T3 cell neutral red uptake phototoxicity (3T3 NRU PT) test, which had been scientifically validated between 1992 and 1996. Since all the UV filter chemicals on the positive list of EU Directive 76/768/EEC have been shown not to be phototoxic in vivo in humans under use conditions, only negative effects would be expected in the 3T3 NRU PT test. To balance the number of positive and negative chemicals, ten phototoxic and ten non-phototoxic chemicals were tested under blind conditions in four laboratories. Moreover, to assess the optimum concentration range for testing, information was provided on appropriate solvents and on the solubility of the coded chemicals. In this study, the phototoxic potential of test chemicals was evaluated in a prediction model in which either the Photoirritation Factor (PIF) or the Mean Photo Effect (MPE) were determined. The results obtained with both PIF and MPE were highly reproducible in the four laboratories, and the correlation between in vitro and in vivo data was almost perfect. All the phototoxic test chemicals provided a positive result at concentrations of 1μg/ml, while nine of the ten non-phototoxic chemicals gave clear negative results, even at the highest test concentrations. One of the UV filter chemicals gave positive results in three of the four laboratories only at concentrations greater than 100μg/ml; the other laboratory correctly identified all 20 of the test chemicals. An analysis of the impact that exposure concentrations had on the performance of the test revealed that the optimum concentration range in the 3T3 NRU PT test for determining the phototoxic potential of chemicals is between 0.1μg/ml and 10μg/ml, and that false positive results can be obtained at concentrations greater than 100μg/ml. Therefore, the positive results obtained with some of the UV filter chemicals only at concentrations greater than 100μg/ml do not indicate a phototoxic potential in vivo. When this information was taken into account during calculation of the overall predictivity of the 3T3 NRU PT test in the present study, an almost perfect correlation of in vitro versus in vivo results was obtained (between 95% and 100%), when either PIF or MPE were used to predict the phototoxic potential. The management team and participants therefore conclude that the 3T3 NRU PT test is a valid test for correctly assessing the phototoxic potential of UV filter chemicals, if the defined concentration limits are taken into account.
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Affiliation(s)
| | - Michael Balls
- WU/ECVAM, JRC Insitute of Health & Consumer Protection, 21020 Ispra, Italy
| | - Jack Dupuis
- COLIPA, 223 rue de la Loi, 1040 Brussels, Belgium
| | | | - Odile de Silva
- L'Oréal, 1 Avenue Eugéne Schueller, 93600 Aulnay-sous-Bois, France
| | - Hermann-Georg Holzhütter
- Humboldt University Medical School (Charité), Institute of Biochemistry, Hessische Strasse 3–4, 10115 Berlin, Germany
| | | | | | - Will W. Lovell
- Unilever Research, Colworth House, Sharnbrook, Bedfordshire MK44 1LQ, UK
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14
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Archer G, Balls M, Bruner LH, Curren RD, Fentem JH, Holzhütter HG, Liebsch M, Lovell DP, Southee JA. The Validation of Toxicological Prediction Models. Altern Lab Anim 2020. [DOI: 10.1177/026119299702500507] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
An alternative method is shown to consist of two parts: the test system itself; and a prediction model for converting in vitro endpoints into predictions of in vivo toxicity. For the alternative method to be relevant and reliable, it is important that its prediction model component is of high predictive power and is sufficiently robust against sources of data variability. In other words, the prediction model must be subjected to criticism, leading successful models to the state of confirmation. It is shown that there are certain circumstances in which a new prediction model may be introduced without the necessity to generate new test system data.
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Affiliation(s)
- Graeme Archer
- ECVAM, JRC Environment Institute, 21020 Ispra (VA), Italy
| | - Michael Balls
- ECVAM, JRC Environment Institute, 21020 Ispra (VA), Italy
| | - Leon H. Bruner
- The Procter & Gamble Company, Health and Beauty Care Europe, Egham, Surrey TW20 9NW, UK
| | - Rodger D. Curren
- Institute for In Vitro Sciences Inc., Suite 220, 21 Firstfield Road, Gaithersburg, MD 20878, USA
| | | | - Hermann-Georg Holzhütter
- Humboldt-Universität zu Berlin, Bereich Medizin (Charité), Institut für Biochemie, Mon Bijou Strasse 2a, 10117 Berlin, Germany
| | - Manfred Liebsch
- ZEBET, Bundesinstitut für gesundheitlichen Verbraucherschutz und Veterinärmedizin (BgVV), Diedersdorfer Weg 1, 12277 Berlin, Germany
| | - David P. Lovell
- BIBRA International, Woodmansterne Road, Carshalton, Surrey SM5 4DS, UK
| | - Jacqueline A. Southee
- Microbiological Associates Ltd, Stirling University Innovation Park, Stirling FK9 4NF, UK
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15
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Holzhütter HG. A General Measure of In Vitro Phototoxicity Derived from Pairs of Dose-Response Curves and its Use for Predicting the In Vivo Phototoxicity of Chemicals. Altern Lab Anim 2020. [DOI: 10.1177/026119299702500407] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In pharmacology, it is common to evaluate the influence of external effectors (for example, temperature, pH, and presence of a second drug) on dose-response relations by the potency factor (PF50): [Formula: see text] where ED50 (± effector) denotes the 50% effective dose in the presence and in the absence of the effector, respectively. In this paper, the external effector is ultraviolet (UV) light, and PF50 is referred to as the photoirritancy factor (PIF). There are two parameters which limit the applicability and toxicological reliability of the PIF. Firstly, the physical properties (for example, water solubility) of the chemical tested and the constraints of the biological test system may make it difficult, or even impossible, to achieve sufficiently high doses to observe 50% of the maximal response. In such cases, no numeric value of the potency factor can be computed. Secondly, the potency factor does not take into account the absolute change in response induced by UV light, i.e. depending on the shape of the ±UV dose-response curves, the absolute change in response may be small although the PIF is large, and vice versa. This paper proposes a more general measure of phototoxicity, the mean photo effect (MPE), which can be assessed from pairs of dose-response curves, even if the 50% response level is not reached in one curve or in both. The MPE is a weighted average of PIFd values across different dose levels (d being common to both dose-response curves). The absolute response changes, ΔRd, i.e. the differences between the -UV curve and the +UV curve are used as weighting factors. The numerical computation of the MPE is based on theoretical curves obtained by fitting a mathematical model to the experimental dose-response data. Plotting PIFd and ΔRd versus the corresponding doses permits differences in the shapes of the two curves to be assessed, and possible alterations in the toxic mechanisms induced by UV light to be revealed. The variance of MPE is estimated by a bootstrap procedure. The use of the MPE is illustrated by its application to dose-response data obtained with a human keratinocyte assay of fibroblasts in the EU/COLIPA international validation project on photoirritancy.
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Affiliation(s)
- Hermann-Georg Holzhütter
- Humboldt-Universität zu Berlin, Medizinische Fakultät (Charité), Institut für Biochemie, Monbijoustrasse 2a, 10117 Berlin, Germany
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16
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Holzhütter HG, Wuensch T, Gajowski R, Berndt N, Bulik S, Meierhofer D, Stockmann M. A novel variant of the 13C-methacetin liver function breath test that eliminates the confounding effect of individual differences in systemic CO 2 kinetics. Arch Toxicol 2020; 94:401-415. [PMID: 32020249 DOI: 10.1007/s00204-020-02654-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 01/27/2020] [Indexed: 12/23/2022]
Abstract
The principle of dynamic liver function breath tests is founded on the administration of a 13C-labeled drug and subsequent monitoring of 13CO2 in the breath, quantified as time series delta over natural baseline 13CO2 (DOB) liberated from the drug during hepatic CYP-dependent detoxification. One confounding factor limiting the diagnostic value of such tests is that only a fraction of the liberated 13CO2 is immediately exhaled, while another fraction is taken up by body compartments from which it returns with delay to the plasma. The aims of this study were to establish a novel variant of the methacetin-based breath test LiMAx that allows to estimate and to eliminate the confounding effect of systemic 13CO2 distribution on the DOB curve and thus enables a more reliable assessment of the hepatic detoxification capacity compared with the conventional LiMAx test. We designed a new test variant (named "2DOB") consisting of two consecutive phases. Phase 1 is initiated by the intravenous administration of 13C-bicarbonate. Phase 2 starts about 30 min later with the intravenous administration of the 13C-labelled test drug. Using compartment modelling, the resulting 2-phasic DOB curve yields the rate constants for the irreversible elimination and the reversible exchange of plasma 13CO2 with body compartments (phase 1) and for the detoxification and exchange of the drug with body compartments (phase 2). We carried out the 2DOB test with the test drug 13C-methacetin in 16 subjects with chronic liver pathologies and 22 normal subjects, who also underwent the conventional LiMAx test. Individual differences in the systemic CO2 kinetics can lead to deviations up to a factor of 2 in the maximum of DOB curves (coefficient of variation CV ≈ 0.2) which, in particular, may hamper the discrimination between subjects with normal or mildly impaired detoxification capacities. The novel test revealed that a significant portion of the drug is not immediately metabolized, but transiently taken up into a storage compartment. Intriguingly, not only the hepatic detoxification rate but also the storage capacity of the drug, turned out to be indicative for a normal liver function. We thus used both parameters to define a scoring function which yielded an excellent disease classification (AUC = 0.95) and a high correlation with the MELD score (RSpearman = 0.92). The novel test variant 2DOB promises a significant improvement in the assessment of impaired hepatic detoxification capacity. The suitability of the test for the reliable characterization of the natural history of chronic liver diseases (fatty liver-fibrosis-cirrhosis) has to be assessed in further studies.
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Affiliation(s)
- Hermann-Georg Holzhütter
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Biochemistry, Computational Systems Biochemistry Group, Charitéplatz 1, 10117, Berlin, Germany.
| | - Tilo Wuensch
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Surgery, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Robert Gajowski
- Max Planck Institute of Molecular Genetics, Mass Spectroscopy Facility, Ihnestraße 63-73, 14195, Berlin, Germany
- Department of Biology, Chemistry, and Pharmacy, Free University Berlin, Takustraße 3, 14195, Berlin, Germany
| | - Nikolaus Berndt
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Biochemistry, Computational Systems Biochemistry Group, Charitéplatz 1, 10117, Berlin, Germany
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute for Computational and Imaging Science in Cardiovascular Medicine, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Sascha Bulik
- Federal Institute of Risk Assessment, Diedersdorfer Weg 1, 12277, Berlin, Germany
| | - David Meierhofer
- Max Planck Institute of Molecular Genetics, Mass Spectroscopy Facility, Ihnestraße 63-73, 14195, Berlin, Germany
| | - Martin Stockmann
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Surgery, Augustenburger Platz 1, 13353, Berlin, Germany
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Berndt N, Patzak A, Holzhütter HG. Metabolic modelling of kidney diseases: Lessons learned from the liver. Acta Physiol (Oxf) 2019; 227:e13350. [PMID: 31348847 DOI: 10.1111/apha.13350] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 07/19/2019] [Accepted: 07/23/2019] [Indexed: 12/31/2022]
Affiliation(s)
- Nikolaus Berndt
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Institute for Computational and Imaging Science in Cardiovascular Medicine, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Andreas Patzak
- Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
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18
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Schneider J, Berndt N, Papageorgiou IE, Maurer J, Bulik S, Both M, Draguhn A, Holzhütter HG, Kann O. Local oxygen homeostasis during various neuronal network activity states in the mouse hippocampus. J Cereb Blood Flow Metab 2019; 39:859-873. [PMID: 29099662 PMCID: PMC6501513 DOI: 10.1177/0271678x17740091] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cortical information processing comprises various activity states emerging from timed synaptic excitation and inhibition. However, the underlying energy metabolism is widely unknown. We determined the cerebral metabolic rate of oxygen (CMRO2) along a tissue depth of <0.3 mm in the hippocampal CA3 region during various network activities, including gamma oscillations and sharp wave-ripples that occur during wakefulness and sleep. These physiological states associate with sensory perception and memory formation, and critically depend on perisomatic GABA inhibition. Moreover, we modelled vascular oxygen delivery based on quantitative microvasculature analysis. (1) Local CMRO2 was highest during gamma oscillations (3.4 mM/min), medium during sharp wave-ripples, asynchronous activity and isoflurane application (2.0-1.6 mM/min), and lowest during tetrodotoxin application (1.4 mM/min). (2) Energy expenditure of axonal and synaptic signaling accounted for >50% during gamma oscillations. (3) CMRO2 positively correlated with number and synchronisation of activated synapses, and neural multi-unit activity. (4) The median capillary distance was 44 µm. (5) The vascular oxygen partial pressure of 33 mmHg was needed to sustain oxidative phosphorylation during gamma oscillations. We conclude that gamma oscillations featuring high energetics require a hemodynamic response to match oxygen consumption of respiring mitochondria, and that perisomatic inhibition significantly contributes to the brain energy budget.
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Affiliation(s)
- Justus Schneider
- 1 Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Nikolaus Berndt
- 2 Computational Systems Biochemistry, Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Ismini E Papageorgiou
- 1 Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Jana Maurer
- 1 Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Sascha Bulik
- 2 Computational Systems Biochemistry, Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Martin Both
- 1 Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Andreas Draguhn
- 1 Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
| | - Hermann-Georg Holzhütter
- 2 Computational Systems Biochemistry, Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Oliver Kann
- 1 Institute of Physiology and Pathophysiology, and Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
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Liebsch M, Traue D, Barrabas C, Spielmann H, Uphill P, Wilkins S, McPherson JP, Wiemann C, Kaufmann T, Remmele M, Holzhütter HG. The ECVAM Prevalidation Study on the Use of EpiDerm for Skin Corrosivity Testing. Altern Lab Anim 2019; 28:371-401. [DOI: 10.1177/026119290002800309] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
| | - Dieter Traue
- ZEBET, BgVV, Diedersdorfer Weg 1, 12277 Berlin, Germany
| | | | | | - Patricia Uphill
- Huntingdon Life Sciences, Huntingdon, Cambridgeshire PE18 6ES, UK
| | - Susan Wilkins
- Huntingdon Life Sciences, Huntingdon, Cambridgeshire PE18 6ES, UK
| | | | | | - Tanja Kaufmann
- BASF AG, Department of Product Safety, 67056 Ludwigshafen, Germany
| | - Martina Remmele
- BASF AG, Department of Product Safety, 67056 Ludwigshafen, Germany
| | - Hermann-Georg Holzhütter
- Institut für Biochemie, Humboldt-Universität zu Berlin, Monbijoustrasse 2a, 10117 Berlin, Germany
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20
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Hudert CA, Selinski S, Rudolph B, Bläker H, Loddenkemper C, Thielhorn R, Berndt N, Golka K, Cadenas C, Reinders J, Henning S, Bufler P, Jansen PLM, Holzhütter HG, Meierhofer D, Hengstler JG, Wiegand S. Genetic determinants of steatosis and fibrosis progression in paediatric non-alcoholic fatty liver disease. Liver Int 2019; 39:540-556. [PMID: 30444569 DOI: 10.1111/liv.14006] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 11/05/2018] [Accepted: 11/05/2018] [Indexed: 02/06/2023]
Abstract
BACKGROUND AND AIMS Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in children and adolescents today. In comparison with adult disease, paediatric NAFLD may show a periportal localization, which is associated with advanced fibrosis. This study aimed to assess the role of genetic risk variants for histological disease pattern and severity in childhood NAFLD. METHODS We studied 14 single nucleotide polymorphisms (SNP) in a cohort of 70 adolescents with biopsy-proven NAFLD. Genotype was compared to an adult control cohort (n = 200) and analysed in relation to histological disease severity and liver tissue proteomics. RESULTS Three of the 14 SNPs were significantly associated with paediatric NAFLD after FDR adjustment, rs738409 (PNPLA3, P = 2.80 × 10-06 ), rs1044498 (ENPP1, P = 0.0091) and rs780094 (GCKR, P = 0.0281). The severity of steatosis was critically associated with rs738409 (OR=3.25; 95% CI: 1.72-6.52, FDR-adjusted P = 0.0070). The strongest variants associated with severity of fibrosis were rs1260326, rs780094 (both GCKR) and rs659366 (UCP2). PNPLA3 was associated with a portal pattern of steatosis, inflammation and fibrosis. Proteome profiling revealed decreasing levels of GCKR protein with increasing carriage of the rs1260326/rs780094 minor alleles and downregulation of the retinol pathway in rs738409 G/G carriers. Computational metabolic modelling highlighted functional relevance of PNPLA3, GCKR and UCP2 for NAFLD development. CONCLUSIONS This study provides evidence for the role of PNPLA3 as a determinant of portal NAFLD localization and severity of portal fibrosis in children and adolescents, the risk variant being associated with an impaired hepatic retinol metabolism.
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Affiliation(s)
- Christian A Hudert
- Center for Chronically Sick Children, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Silvia Selinski
- Systems Toxicology, Leibniz Research Centre for Working Environment and Human Factors at the Technical University Dortmund, Dortmund, Germany
| | - Birgit Rudolph
- Institute of Pathology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Hendrik Bläker
- Institute of Pathology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | | | - Ria Thielhorn
- Max Planck Institute for Molecular Genetics, Mass Spectrometry Facility, Berlin, Germany
| | - Nikolaus Berndt
- Institute for Biochemistry, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Klaus Golka
- Systems Toxicology, Leibniz Research Centre for Working Environment and Human Factors at the Technical University Dortmund, Dortmund, Germany
| | - Cristina Cadenas
- Systems Toxicology, Leibniz Research Centre for Working Environment and Human Factors at the Technical University Dortmund, Dortmund, Germany
| | - Jörg Reinders
- Systems Toxicology, Leibniz Research Centre for Working Environment and Human Factors at the Technical University Dortmund, Dortmund, Germany
| | - Stephan Henning
- Department of Pediatric Gastroenterology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Philip Bufler
- Department of Pediatric Gastroenterology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Peter L M Jansen
- Department of Gastroenterology and Hepatology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | | | - David Meierhofer
- Max Planck Institute for Molecular Genetics, Mass Spectrometry Facility, Berlin, Germany
| | - Jan G Hengstler
- Systems Toxicology, Leibniz Research Centre for Working Environment and Human Factors at the Technical University Dortmund, Dortmund, Germany
| | - Susanna Wiegand
- Center for Chronically Sick Children, Charité - Universitätsmedizin Berlin, Berlin, Germany
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21
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Berndt N, Holzhütter HG. Dynamic Metabolic Zonation of the Hepatic Glucose Metabolism Is Accomplished by Sinusoidal Plasma Gradients of Nutrients and Hormones. Front Physiol 2018; 9:1786. [PMID: 30631280 PMCID: PMC6315134 DOI: 10.3389/fphys.2018.01786] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 11/28/2018] [Indexed: 12/19/2022] Open
Abstract
Being the central metabolic organ of vertebrates, the liver possesses the largest repertoire of metabolic enzymes among all tissues and organs. Almost all metabolic pathways are resident in the parenchymal cell, hepatocyte, but the pathway capacities may largely differ depending on the localization of hepatocytes within the liver acinus-a phenomenon that is commonly referred to as metabolic zonation. Metabolic zonation is rather dynamic since gene expression patterns of metabolic enzymes may change in response to nutrition, drugs, hormones and pathological states of the liver (e.g., fibrosis and inflammation). This fact has to be ultimately taken into account in mathematical models aiming at the prediction of metabolic liver functions in different physiological and pathological settings. Here we present a spatially resolved kinetic tissue model of hepatic glucose metabolism which includes zone-specific temporal changes of enzyme abundances which are driven by concentration gradients of nutrients, hormones and oxygen along the hepatic sinusoids. As key modulators of enzyme expression we included oxygen, glucose and the hormones insulin and glucagon which also control enzyme activities by cAMP-dependent reversible phosphorylation. Starting with an initially non-zonated model using plasma profiles under fed, fasted and diabetic conditions, zonal patterns of glycolytic and gluconeogenetic enzymes as well as glucose uptake and release rates are created as an emergent property. We show that mechanisms controlling the adaptation of enzyme abundances to varying external conditions necessarily lead to the zonation of hepatic carbohydrate metabolism. To the best of our knowledge, this is the first kinetic tissue model which takes into account in a semi-mechanistic way all relevant levels of enzyme regulation.
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Affiliation(s)
- Nikolaus Berndt
- Computational Biochemistry Group, Institute of Biochemistry, Charite-University Medicine Berlin, Berlin, Germany.,Institute for Computational and Imaging Science in Cardiovascular Medicine, Charite-University Medicine Berlin, Berlin, Germany
| | - Hermann-Georg Holzhütter
- Computational Biochemistry Group, Institute of Biochemistry, Charite-University Medicine Berlin, Berlin, Germany
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22
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Berndt N, Rösner J, Haq RU, Kann O, Kovács R, Holzhütter HG, Spies C, Liotta A. Possible neurotoxicity of the anesthetic propofol: evidence for the inhibition of complex II of the respiratory chain in area CA3 of rat hippocampal slices. Arch Toxicol 2018; 92:3191-3205. [PMID: 30143847 PMCID: PMC6132669 DOI: 10.1007/s00204-018-2295-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 08/20/2018] [Indexed: 12/14/2022]
Abstract
Propofol is the most frequently used intravenous anesthetic for induction and maintenance of anesthesia. Propofol acts first and formost as a GABAA-agonist, but effects on other neuronal receptors and voltage-gated ion channels have been described. Besides its direct effect on neurotransmission, propofol-dependent impairment of mitochondrial function in neurons has been suggested to be responsible for neurotoxicity and postoperative brain dysfunction. To clarify the potential neurotoxic effect in more detail, we investigated the effects of propofol on neuronal energy metabolism of hippocampal slices of the stratum pyramidale of area CA3 at different activity states. We combined oxygen-measurements, electrophysiology and flavin adenine dinucleotide (FAD)-imaging with computational modeling to uncover molecular targets in mitochondrial energy metabolism that are directly inhibited by propofol. We found that high concentrations of propofol (100 µM) significantly decrease population spikes, paired pulse ratio, the cerebral metabolic rate of oxygen consumption (CMRO2), frequency and power of gamma oscillations and increase FAD-oxidation. Model-based simulation of mitochondrial FAD redox state at inhibition of different respiratory chain (RC) complexes and the pyruvate-dehydrogenase show that the alterations in FAD-autofluorescence during propofol administration can be explained with a strong direct inhibition of the complex II (cxII) of the RC. While this inhibition may not affect ATP availability under normal conditions, it may have an impact at high energy demand. Our data support the notion that propofol may lead to neurotoxicity and neuronal dysfunction by directly affecting the energy metabolism in neurons.
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Affiliation(s)
- Nikolaus Berndt
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany.,Institute for Computational and Imaging Science in Cardiovascular Medicine Charité, Universitätsmedizin Berlin, 13353, Berlin, Germany
| | - Jörg Rösner
- Neuroscience Research Center, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Rizwan Ul Haq
- Neuroscience Research Center, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Oliver Kann
- Institute of Physiology and Pathophysiology, University of Heidelberg, 69120, Heidelberg, Germany
| | - Richard Kovács
- Institute for Neurophysiology, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | | | - Claudia Spies
- Department of Anesthesiology and Intensive Care, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany.,Berlin Institute of Health, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Agustin Liotta
- Neuroscience Research Center, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany. .,Department of Anesthesiology and Intensive Care, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany. .,Berlin Institute of Health, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany.
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23
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Hudert CA, Tzschätzsch H, Guo J, Rudolph B, Bläker H, Loddenkemper C, Luck W, Müller HP, Baumgart DC, Hamm B, Braun J, Holzhütter HG, Wiegand S, Sack I. US Time-Harmonic Elastography: Detection of Liver Fibrosis in Adolescents with Extreme Obesity with Nonalcoholic Fatty Liver Disease. Radiology 2018; 288:99-106. [DOI: 10.1148/radiol.2018172928] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Christian A. Hudert
- From the Center for Chronically Sick Children (C.A.H., S.W.), Departments of Radiology (H.T., J.G., B.H., I.S.), Pathology (B.R., H.B., C.L.), Pediatric Gastroenterology (W.L.), and Gastroenterology and Hepatology (H.P.M., D.C.B.), and the Institutes for Medical Informatics (J.B.) and Biochemistry (H.G.H.), Charité–Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Heiko Tzschätzsch
- From the Center for Chronically Sick Children (C.A.H., S.W.), Departments of Radiology (H.T., J.G., B.H., I.S.), Pathology (B.R., H.B., C.L.), Pediatric Gastroenterology (W.L.), and Gastroenterology and Hepatology (H.P.M., D.C.B.), and the Institutes for Medical Informatics (J.B.) and Biochemistry (H.G.H.), Charité–Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Jing Guo
- From the Center for Chronically Sick Children (C.A.H., S.W.), Departments of Radiology (H.T., J.G., B.H., I.S.), Pathology (B.R., H.B., C.L.), Pediatric Gastroenterology (W.L.), and Gastroenterology and Hepatology (H.P.M., D.C.B.), and the Institutes for Medical Informatics (J.B.) and Biochemistry (H.G.H.), Charité–Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Birgit Rudolph
- From the Center for Chronically Sick Children (C.A.H., S.W.), Departments of Radiology (H.T., J.G., B.H., I.S.), Pathology (B.R., H.B., C.L.), Pediatric Gastroenterology (W.L.), and Gastroenterology and Hepatology (H.P.M., D.C.B.), and the Institutes for Medical Informatics (J.B.) and Biochemistry (H.G.H.), Charité–Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Hendrik Bläker
- From the Center for Chronically Sick Children (C.A.H., S.W.), Departments of Radiology (H.T., J.G., B.H., I.S.), Pathology (B.R., H.B., C.L.), Pediatric Gastroenterology (W.L.), and Gastroenterology and Hepatology (H.P.M., D.C.B.), and the Institutes for Medical Informatics (J.B.) and Biochemistry (H.G.H.), Charité–Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Christoph Loddenkemper
- From the Center for Chronically Sick Children (C.A.H., S.W.), Departments of Radiology (H.T., J.G., B.H., I.S.), Pathology (B.R., H.B., C.L.), Pediatric Gastroenterology (W.L.), and Gastroenterology and Hepatology (H.P.M., D.C.B.), and the Institutes for Medical Informatics (J.B.) and Biochemistry (H.G.H.), Charité–Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Werner Luck
- From the Center for Chronically Sick Children (C.A.H., S.W.), Departments of Radiology (H.T., J.G., B.H., I.S.), Pathology (B.R., H.B., C.L.), Pediatric Gastroenterology (W.L.), and Gastroenterology and Hepatology (H.P.M., D.C.B.), and the Institutes for Medical Informatics (J.B.) and Biochemistry (H.G.H.), Charité–Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Hans-Peter Müller
- From the Center for Chronically Sick Children (C.A.H., S.W.), Departments of Radiology (H.T., J.G., B.H., I.S.), Pathology (B.R., H.B., C.L.), Pediatric Gastroenterology (W.L.), and Gastroenterology and Hepatology (H.P.M., D.C.B.), and the Institutes for Medical Informatics (J.B.) and Biochemistry (H.G.H.), Charité–Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Daniel C. Baumgart
- From the Center for Chronically Sick Children (C.A.H., S.W.), Departments of Radiology (H.T., J.G., B.H., I.S.), Pathology (B.R., H.B., C.L.), Pediatric Gastroenterology (W.L.), and Gastroenterology and Hepatology (H.P.M., D.C.B.), and the Institutes for Medical Informatics (J.B.) and Biochemistry (H.G.H.), Charité–Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Bernd Hamm
- From the Center for Chronically Sick Children (C.A.H., S.W.), Departments of Radiology (H.T., J.G., B.H., I.S.), Pathology (B.R., H.B., C.L.), Pediatric Gastroenterology (W.L.), and Gastroenterology and Hepatology (H.P.M., D.C.B.), and the Institutes for Medical Informatics (J.B.) and Biochemistry (H.G.H.), Charité–Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Jürgen Braun
- From the Center for Chronically Sick Children (C.A.H., S.W.), Departments of Radiology (H.T., J.G., B.H., I.S.), Pathology (B.R., H.B., C.L.), Pediatric Gastroenterology (W.L.), and Gastroenterology and Hepatology (H.P.M., D.C.B.), and the Institutes for Medical Informatics (J.B.) and Biochemistry (H.G.H.), Charité–Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Hermann-Georg Holzhütter
- From the Center for Chronically Sick Children (C.A.H., S.W.), Departments of Radiology (H.T., J.G., B.H., I.S.), Pathology (B.R., H.B., C.L.), Pediatric Gastroenterology (W.L.), and Gastroenterology and Hepatology (H.P.M., D.C.B.), and the Institutes for Medical Informatics (J.B.) and Biochemistry (H.G.H.), Charité–Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Susanna Wiegand
- From the Center for Chronically Sick Children (C.A.H., S.W.), Departments of Radiology (H.T., J.G., B.H., I.S.), Pathology (B.R., H.B., C.L.), Pediatric Gastroenterology (W.L.), and Gastroenterology and Hepatology (H.P.M., D.C.B.), and the Institutes for Medical Informatics (J.B.) and Biochemistry (H.G.H.), Charité–Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Ingolf Sack
- From the Center for Chronically Sick Children (C.A.H., S.W.), Departments of Radiology (H.T., J.G., B.H., I.S.), Pathology (B.R., H.B., C.L.), Pediatric Gastroenterology (W.L.), and Gastroenterology and Hepatology (H.P.M., D.C.B.), and the Institutes for Medical Informatics (J.B.) and Biochemistry (H.G.H.), Charité–Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
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Berndt N, Bulik S, Wallach I, Wünsch T, König M, Stockmann M, Meierhofer D, Holzhütter HG. HEPATOKIN1 is a biochemistry-based model of liver metabolism for applications in medicine and pharmacology. Nat Commun 2018; 9:2386. [PMID: 29921957 PMCID: PMC6008457 DOI: 10.1038/s41467-018-04720-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 05/14/2018] [Indexed: 12/18/2022] Open
Abstract
The epidemic increase of non-alcoholic fatty liver diseases (NAFLD) requires a deeper understanding of the regulatory circuits controlling the response of liver metabolism to nutritional challenges, medical drugs, and genetic enzyme variants. As in vivo studies of human liver metabolism are encumbered with serious ethical and technical issues, we developed a comprehensive biochemistry-based kinetic model of the central liver metabolism including the regulation of enzyme activities by their reactants, allosteric effectors, and hormone-dependent phosphorylation. The utility of the model for basic research and applications in medicine and pharmacology is illustrated by simulating diurnal variations of the metabolic state of the liver at various perturbations caused by nutritional challenges (alcohol), drugs (valproate), and inherited enzyme disorders (galactosemia). Using proteomics data to scale maximal enzyme activities, the model is used to highlight differences in the metabolic functions of normal hepatocytes and malignant liver cells (adenoma and hepatocellular carcinoma). In silico models of cells can provide insight into the causes and effects of disease states and reduce the need for in vivo studies. Here, the authors present a kinetic model of hepatocyte metabolism including energy, carbohydrate, lipid and nitrogen metabolism and hormonal and allosteric regulation of enzymatic activity.
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Affiliation(s)
- Nikolaus Berndt
- Institute of Biochemistry Computational Systems Biochemistry Group, Charité - Universitätsmedizin Berlin, Charitéplatz, 110117, Berlin, Germany
| | - Sascha Bulik
- Institute of Biochemistry Computational Systems Biochemistry Group, Charité - Universitätsmedizin Berlin, Charitéplatz, 110117, Berlin, Germany.,German Federal Institute for Risk Assessment Max-Dohrn-Straße 8-10, 10589, Berlin, Germany
| | - Iwona Wallach
- Institute of Biochemistry Computational Systems Biochemistry Group, Charité - Universitätsmedizin Berlin, Charitéplatz, 110117, Berlin, Germany
| | - Tilo Wünsch
- Department of General, Visceral and Transplantation Surgery Augustenburger Platz, Charité - Universitätsmedizin Berlin - Campus Virchow-Klinikum, 113353, Berlin, Germany
| | - Matthias König
- Institute for Biology, Institute for Theoretical Biology, Humboldt-University Berlin, Invalidenstraße 43, Haus, 410115, Berlin, Germany
| | - Martin Stockmann
- German Federal Institute for Risk Assessment Max-Dohrn-Straße 8-10, 10589, Berlin, Germany
| | - David Meierhofer
- Max Planck Institute of Molecular Genetics/Mass Spectroscopy, Ihnestraße 63-73, 14195, Berlin, Germany
| | - Hermann-Georg Holzhütter
- Institute of Biochemistry Computational Systems Biochemistry Group, Charité - Universitätsmedizin Berlin, Charitéplatz, 110117, Berlin, Germany.
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Eckstein J, Holzhütter HG, Berndt N. Correction: The importance of membrane microdomains for bile salt-dependent biliary lipid secretion (doi:10.1242/jcs.211524). J Cell Sci 2018; 131:131/6/jcs217414. [PMID: 29555875 DOI: 10.1242/jcs.217414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Eckstein J, Holzhütter HG, Berndt N. The importance of membrane microdomains for bile salt-dependent biliary lipid secretion. J Cell Sci 2018; 131:jcs211524. [PMID: 29420298 PMCID: PMC5897720 DOI: 10.1242/jcs.211524] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 01/23/2018] [Indexed: 12/13/2022] Open
Abstract
Alternative models explaining the biliary lipid secretion at the canalicular membrane of hepatocytes exist: successive lipid extraction by preformed bile salt micelles, or budding of membrane fragments with formation of mixed micelles. To test the feasibility of the latter mechanism, we developed a mathematical model that describes the formation of lipid microdomains in the canalicular membrane. Bile salt monomers intercalate into the external hemileaflet of the canalicular membrane, to form a rim to liquid disordered domain patches that then pinch off to form nanometer-scale mixed micelles. Model simulations perfectly recapitulate the measured dependence of bile salt-dependent biliary lipid extraction rates upon modulation of the membrane cholesterol (lack or overexpression of the cholesterol transporter Abcg5-Abcg8) and phosphatidylcholine (lack of Mdr2, also known as Abcb4) content. The model reveals a strong dependence of the biliary secretion rate on the protein density of the membrane. Taken together, the proposed model is consistent with crucial experimental findings in the field and provides a consistent explanation of the central molecular processes involved in bile formation.
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Affiliation(s)
- Johannes Eckstein
- Charité - Universitätsmedizin Berlin, Institute of Biochemistry, Charitéplatz 1, 10117 Berlin, Germany
| | - Hermann-Georg Holzhütter
- Charité - Universitätsmedizin Berlin, Institute of Biochemistry, Charitéplatz 1, 10117 Berlin, Germany
| | - Nikolaus Berndt
- Charité - Universitätsmedizin Berlin, Institute of Biochemistry, Charitéplatz 1, 10117 Berlin, Germany
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Berndt N, Horger MS, Bulik S, Holzhütter HG. A multiscale modelling approach to assess the impact of metabolic zonation and microperfusion on the hepatic carbohydrate metabolism. PLoS Comput Biol 2018; 14:e1006005. [PMID: 29447152 PMCID: PMC5841820 DOI: 10.1371/journal.pcbi.1006005] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 03/07/2018] [Accepted: 01/26/2018] [Indexed: 12/11/2022] Open
Abstract
The capacity of the liver to convert the metabolic input received from the incoming portal and arterial blood into the metabolic output of the outgoing venous blood has three major determinants: The intra-hepatic blood flow, the transport of metabolites between blood vessels (sinusoids) and hepatocytes and the metabolic capacity of hepatocytes. These determinants are not constant across the organ: Even in the normal organ, but much more pronounced in the fibrotic and cirrhotic liver, regional variability of the capillary blood pressure, tissue architecture and the expression level of metabolic enzymes (zonation) have been reported. Understanding how this variability may affect the regional metabolic capacity of the liver is important for the interpretation of functional liver tests and planning of pharmacological and surgical interventions. Here we present a mathematical model of the sinusoidal tissue unit (STU) that is composed of a single sinusoid surrounded by the space of Disse and a monolayer of hepatocytes. The total metabolic output of the liver (arterio-venous glucose difference) is obtained by integration across the metabolic output of a representative number of STUs. Application of the model to the hepatic glucose metabolism provided the following insights: (i) At portal glucose concentrations between 6–8 mM, an intra-sinusoidal glucose cycle may occur which is constituted by glucose producing periportal hepatocytes and glucose consuming pericentral hepatocytes, (ii) Regional variability of hepatic blood flow is higher than the corresponding regional variability of the metabolic output, (iii) a spatially resolved metabolic functiogram of the liver is constructed. Variations of tissue parameters are equally important as variations of enzyme activities for the control of the arterio-venous glucose difference. Glucose homeostasis is one of the central liver functions. The liver extracts glucose from the blood when plasma glucose levels are high and produces glucose when plasma glucose levels are low. To fulfill this function the liver is organized in smallest functional units, the sinusoidal tissue units (STUs). These STUs consist of a single sinusoid surrounded by linear arranged hepatocytes. Liver zonation describes the spatial separation of metabolic pathways along the STUs. As blood flows through the sinusoid the plasma nutrient and hormone composition changes and in conjunction with the heterogeneous endowment of metabolic enzymes this leads to big differences in the metabolic performance of hepatocytes depending on their position within the sinusoid. This makes liver zonation and blood flow two central determinants for the functional output of the liver. In this work we present a tissue model of hepatic carbohydrate metabolism that combines liver zonation and microperfusion within the STU. We show that structural properties, enzymatic properties and regional bloodflow are equally important for the understanding of liver functionality. With our work we provide a true multi-scale model bridging the scale from the cellular to the tissue level.
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Affiliation(s)
- Nikolaus Berndt
- Computational Biochemistry Group, Institute of Biochemistry, Charite—University Medicine Berlin, Charitéplatz 1, Berlin
- * E-mail:
| | - Marius Stefan Horger
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tubingen, Tuebingen, Germany
| | - Sascha Bulik
- Computational Biochemistry Group, Institute of Biochemistry, Charite—University Medicine Berlin, Charitéplatz 1, Berlin
- German Federal Institute for Risk Assessment, Junior Research Group Supply-Chain-Models, Max-Dohrn-Straße 8–10, Berlin, Germany
| | - Hermann-Georg Holzhütter
- Computational Biochemistry Group, Institute of Biochemistry, Charite—University Medicine Berlin, Charitéplatz 1, Berlin
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Praus M, Kettelgerdes G, Holzhütter HG, Jungblut P, Maissen M, Epple G, Schleuning WD, Köttgen E, Aguzzi A, Geßner R, Baier M. Stimulation of plasminogen activation by recombinant cellular prion protein is conserved in the NH2-terminal fragment PrP23-110. Thromb Haemost 2017. [DOI: 10.1055/s-0037-1613466] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Summary
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29
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Kürschner G, Zhang Q, Clima R, Xiao Y, Busch JF, Kilic E, Jung K, Berndt N, Bulik S, Holzhütter HG, Gasparre G, Attimonelli M, Babu M, Meierhofer D. Renal oncocytoma characterized by the defective complex I of the respiratory chain boosts the synthesis of the ROS scavenger glutathione. Oncotarget 2017; 8:105882-105904. [PMID: 29285300 PMCID: PMC5739687 DOI: 10.18632/oncotarget.22413] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 09/21/2017] [Indexed: 12/15/2022] Open
Abstract
Renal oncocytomas are rare benign tumors of the kidney and characterized by a deficient complex I (CI) enzyme activity of the oxidative phosphorylation (OXPHOS) system caused by mitochondrial DNA (mtDNA) mutations. Yet, little is known about the underlying molecular mechanisms and alterations of metabolic pathways in this tumor. We compared renal oncocytomas with adjacent matched normal kidney tissues on a global scale by multi-omics approaches, including whole exome sequencing (WES), proteomics, metabolomics, and metabolic pathway simulation. The abundance of proteins localized to mitochondria increased more than 2-fold, the only exception was a strong decrease in the abundance for CI subunits that revealed several pathogenic heteroplasmic mtDNA mutations by WES. We also observed renal oncocytomas to dysregulate main metabolic pathways, shunting away from gluconeogenesis and lipid metabolism. Nevertheless, the abundance of energy carrier molecules such as NAD+, NADH, NADP, ATP, and ADP were significantly higher in renal oncocytomas. Finally, a substantial 5000-fold increase of the reactive oxygen species scavenger glutathione can be regarded as a new hallmark of renal oncocytoma. Our findings demonstrate that renal oncocytomas undergo a metabolic switch to eliminate ATP consuming processes to ensure a sufficient energy supply for the tumor.
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Affiliation(s)
- Gerrit Kürschner
- Max Planck Institute for Molecular Genetics, Mass Spectrometry Facility, Berlin, Germany.,Technical University of Berlin, Institute of Bioanalytics, Department of Biotechnology, Berlin, Germany
| | - Qingzhou Zhang
- University of Regina, Department of Biochemistry, Regina, Canada
| | - Rosanna Clima
- University of Bari, Department of Biosciences, Biotechnology and Biopharmaceutics, Bari, Italy.,Department of Medical and Surgical Sciences-DIMEC, Medical Genetics Unit, University of Bologna, Bologna, Italy
| | - Yi Xiao
- Max Planck Institute for Molecular Genetics, Mass Spectrometry Facility, Berlin, Germany.,Freie Universität Berlin, Fachbereich Biologie, Chemie, Pharmazie, Berlin, Germany
| | | | - Ergin Kilic
- University Hospital Charité, Institute of Pathology, Berlin, Germany
| | - Klaus Jung
- University Hospital Charité, Department of Urology, Berlin, Germany.,Berlin Institute for Urologic Research, Berlin, Germany
| | - Nikolaus Berndt
- Charité University Medicine Berlin, Institute of Biochemistry Computational Systems Biochemistry Group, Berlin, Germany
| | - Sascha Bulik
- Charité University Medicine Berlin, Institute of Biochemistry Computational Systems Biochemistry Group, Berlin, Germany
| | - Hermann-Georg Holzhütter
- Charité University Medicine Berlin, Institute of Biochemistry Computational Systems Biochemistry Group, Berlin, Germany
| | - Giuseppe Gasparre
- Department of Medical and Surgical Sciences-DIMEC, Medical Genetics Unit, University of Bologna, Bologna, Italy
| | - Marcella Attimonelli
- University of Bari, Department of Biosciences, Biotechnology and Biopharmaceutics, Bari, Italy
| | - Mohan Babu
- University of Regina, Department of Biochemistry, Regina, Canada
| | - David Meierhofer
- Max Planck Institute for Molecular Genetics, Mass Spectrometry Facility, Berlin, Germany
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30
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Wallstab C, Eleftheriadou D, Schulz T, Damm G, Seehofer D, Borlak J, Holzhütter HG, Berndt N. A unifying mathematical model of lipid droplet metabolism reveals key molecular players in the development of hepatic steatosis. FEBS J 2017; 284:3245-3261. [PMID: 28763157 DOI: 10.1111/febs.14189] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 06/02/2017] [Accepted: 07/28/2017] [Indexed: 12/16/2022]
Abstract
The liver responds to elevated plasma concentrations of free fatty acids (FFAs) with an enhanced uptake of FFAs and their esterification to triacylglycerol (TAG). On the long term, this may result in massive hepatic TAG accumulation called steatosis hepatitis. In hepatocytes, the poor water-soluble TAG is packed in specialized organelles: Lipid droplets (LDs) serving as transient cellular deposit and lipoproteins (LPs) transporting TAG and cholesterol esters to extra-hepatic tissues. The dynamics of these organelles is controlled by a variety of regulatory surface proteins (RSPs). Assembly and export of VLDLs are mainly regulated by the microsomal transfer protein (MTP) and apoprotein B100. Formation and lipolysis of LDs are regulated by several RSPs. The best studied regulators belong to the PAT (Perilipin/Adipophilin/TIP47) and CIDE families. Knockdown or overexpression of SRPs may significantly affect the total number and size distribution of LDs. Intriguingly, a large cell-to-cell heterogeneity with respect to the number and size of LDs has been found in various cell types including hepatocytes. These findings suggest that the extent of cellular lipid accumulation is determined not only by the imbalance between lipid supply and utilization but also by variations in the expression of RSPs and metabolic enzymes. To better understand the relative regulatory impact of individual processes involved in the cellular TAG turnover, we developed a comprehensive kinetic model encompassing the pathways of the fatty acid and triglyceride metabolism and the main molecular processes governing the dynamics of LDs. The model was parametrized such that a large number of experimental in vitro and in vivo findings are correctly recapitulated. A control analysis of the model revealed that variations in the activity of FFA uptake, diacylglycerol acyltransferase (DGAT) 2, and adipose triglyceride lipase (ATGL) have the strongest influence on the cellular TAG level. We used the model to simulate LD size distributions in human hepatoma cells and hepatocytes exposed to a challenge with FFAs. A random fold change by a factor of about two in the activity of RSPs was sufficient to reproduce the large diversity of droplet size distributions observed in individual cells. Under the premise that the same extent of variability of RSPs holds for the intact organ, our model predicts variations in the TAG content of individual hepatocytes by a factor of about 3-6 depending on the nutritional regime. Taken together, our modeling approach integrates numerous experimental findings on individual processes in the cellular TAG metabolism and LD dynamics metabolism to a consistent state-of-the-art dynamic network model that can be used to study how changes in the external conditions or systemic parameters will affect the TAG content of hepatocytes.
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Affiliation(s)
- Christin Wallstab
- Institute of Biochemistry, Computational Systems Biochemistry Group, Charite - University Medicine Berlin, Germany
| | - Dimitra Eleftheriadou
- Institute of Biochemistry, Computational Systems Biochemistry Group, Charite - University Medicine Berlin, Germany
| | - Theresa Schulz
- Clinic for General-, Visceral- and Transplantation Surgery, Charite - University Medicine Berlin, Germany
| | - Georg Damm
- Clinic for General-, Visceral- and Transplantation Surgery, Charite - University Medicine Berlin, Germany.,Department of Hepatobiliary Surgery and Visceral Transplantation, University of Leipzig, Germany
| | - Daniel Seehofer
- Clinic for General-, Visceral- and Transplantation Surgery, Charite - University Medicine Berlin, Germany.,Department of Hepatobiliary Surgery and Visceral Transplantation, University of Leipzig, Germany
| | - Jürgen Borlak
- Centre for Pharmacology and Toxicology, Institute for Pharmaco- and Toxicogenomics, Hannover Medical School, Hannover, Germany
| | - Hermann-Georg Holzhütter
- Institute of Biochemistry, Computational Systems Biochemistry Group, Charite - University Medicine Berlin, Germany
| | - Nikolaus Berndt
- Institute of Biochemistry, Computational Systems Biochemistry Group, Charite - University Medicine Berlin, Germany
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31
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Bulik S, Holzhütter HG, Berndt N. The relative importance of kinetic mechanisms and variable enzyme abundances for the regulation of hepatic glucose metabolism--insights from mathematical modeling. BMC Biol 2016; 14:15. [PMID: 26935066 PMCID: PMC4774192 DOI: 10.1186/s12915-016-0237-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 02/16/2016] [Indexed: 01/09/2023] Open
Abstract
Background Adaptation of the cellular metabolism to varying external conditions is brought about by regulated changes in the activity of enzymes and transporters. Hormone-dependent reversible enzyme phosphorylation and concentration changes of reactants and allosteric effectors are the major types of rapid kinetic enzyme regulation, whereas on longer time scales changes in protein abundance may also become operative. Here, we used a comprehensive mathematical model of the hepatic glucose metabolism of rat hepatocytes to decipher the relative importance of different regulatory modes and their mutual interdependencies in the hepatic control of plasma glucose homeostasis. Results Model simulations reveal significant differences in the capability of liver metabolism to counteract variations of plasma glucose in different physiological settings (starvation, ad libitum nutrient supply, diabetes). Changes in enzyme abundances adjust the metabolic output to the anticipated physiological demand but may turn into a regulatory disadvantage if sudden unexpected changes of the external conditions occur. Allosteric and hormonal control of enzyme activities allow the liver to assume a broad range of metabolic states and may even fully reverse flux changes resulting from changes of enzyme abundances alone. Metabolic control analysis reveals that control of the hepatic glucose metabolism is mainly exerted by enzymes alone, which are differently controlled by alterations in enzyme abundance, reversible phosphorylation, and allosteric effects. Conclusion In hepatic glucose metabolism, regulation of enzyme activities by changes of reactants, allosteric effects, and reversible phosphorylation is equally important as changes in protein abundance of key regulatory enzymes. Electronic supplementary material The online version of this article (doi:10.1186/s12915-016-0237-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sascha Bulik
- Charité - Universitätsmedizin Berlin, Institute of Biochemistry, Computational Systems Biochemistry Group, Charitéplatz 1, 10117, Berlin, Germany.
| | - Hermann-Georg Holzhütter
- Charité - Universitätsmedizin Berlin, Institute of Biochemistry, Computational Systems Biochemistry Group, Charitéplatz 1, 10117, Berlin, Germany.
| | - Nikolaus Berndt
- Charité - Universitätsmedizin Berlin, Institute of Biochemistry, Computational Systems Biochemistry Group, Charitéplatz 1, 10117, Berlin, Germany.
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32
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Abstract
Cellular metabolism basically consists of the conversion of chemical compounds taken up from the extracellular environment into energy (conserved in energy-rich bonds of organic phosphates) and a wide array of organic molecules serving as catalysts (enzymes), information carriers (nucleic acids), and building blocks for cellular structures such as membranes or ribosomes. Metabolic modeling aims at the construction of mathematical representations of the cellular metabolism that can be used to calculate the concentration of cellular molecules and the rates of their mutual chemical interconversion in response to varying external conditions as, for example, hormonal stimuli or supply of essential nutrients. Based on such calculations, it is possible to quantify complex cellular functions as cellular growth, detoxification of drugs and xenobiotic compounds or synthesis of exported molecules. Depending on the specific questions to metabolism addressed, the methodological expertise of the researcher, and available experimental information, different conceptual frameworks have been established, allowing the usage of computational methods to condense experimental information from various layers of organization into (self-) consistent models. Here, we briefly outline the main conceptual frameworks that are currently exploited in metabolism research.
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Affiliation(s)
- Nikolaus Berndt
- Institute of Biochemistry-Computational Systems Biochemistry Group, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Hermann-Georg Holzhütter
- Institute of Biochemistry-Computational Systems Biochemistry Group, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany.
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Liepe J, Holzhütter HG, Bellavista E, Kloetzel PM, Stumpf MPH, Mishto M. Quantitative time-resolved analysis reveals intricate, differential regulation of standard- and immuno-proteasomes. eLife 2015; 4:e07545. [PMID: 26393687 PMCID: PMC4611054 DOI: 10.7554/elife.07545] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 09/18/2015] [Indexed: 12/15/2022] Open
Abstract
Proteasomal protein degradation is a key determinant of protein half-life and hence of cellular processes ranging from basic metabolism to a host of immunological processes. Despite its importance the mechanisms regulating proteasome activity are only incompletely understood. Here we use an iterative and tightly integrated experimental and modelling approach to develop, explore and validate mechanistic models of proteasomal peptide-hydrolysis dynamics. The 20S proteasome is a dynamic enzyme and its activity varies over time because of interactions between substrates and products and the proteolytic and regulatory sites; the locations of these sites and the interactions between them are predicted by the model, and experimentally supported. The analysis suggests that the rate-limiting step of hydrolysis is the transport of the substrates into the proteasome. The transport efficiency varies between human standard- and immuno-proteasomes thereby impinging upon total degradation rate and substrate cleavage-site usage. DOI:http://dx.doi.org/10.7554/eLife.07545.001 Cells have to be able to reliably destroy or remove molecules from their interior that they no longer need. Structures called proteasomes play a central part in this complex process by cutting up and digesting proteins. Mammals have several different types of proteasomes, each made up of several protein ‘subunits’. For example, when a cell experiences inflammation some proteasomes change some of their subunits and form an immuno-proteasome. These immuno-proteasomes tend to break down proteins more quickly than ‘standard’ proteasomes, but it was not clear how they are able to do so. Liepe et al. have now combined experiments and mathematical modelling to construct a detailed model of proteasome activity. The model shows that protein transport into and out of the proteasome chamber are the steps that limit how quickly the proteasomes can break down proteins. Furthermore, these transport processes are also to a large extent responsible for the different rates at which standard and immuno-proteasomes process proteins. Liepe et al. were also able to confirm the existence of regulatory sites within the proteasome, and describe how these are arranged. Problems that alter the rate at which proteasomes break down proteins have been linked to tumors and neurological and autoimmune diseases. Liepe et al.'s model opens up the ability to study how the proteasome's activity is affected by drugs and therefore makes it easier to investigate ways of interfering with this activity for therapeutic purposes. DOI:http://dx.doi.org/10.7554/eLife.07545.002
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Affiliation(s)
- Juliane Liepe
- Centre for Integrative Systems Biology and Bioinformatics, Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Elena Bellavista
- Department of Experimental, Diagnostic and Specialty Medicine, Alma Mater Studiorum, University of Bologna, Bologna, Italy
| | - Peter M Kloetzel
- Institut für Biochemie, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Michael P H Stumpf
- Centre for Integrative Systems Biology and Bioinformatics, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Michele Mishto
- Institut für Biochemie, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Luigi Galvani, Alma Mater Studiorum, University of Bologna, Bologna, Italy
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34
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Drasdo D, Bode J, Dahmen U, Dirsch O, Dooley S, Gebhardt R, Ghallab A, Godoy P, Häussinger D, Hammad S, Hoehme S, Holzhütter HG, Klingmüller U, Kuepfer L, Timmer J, Zerial M, Hengstler JG. The virtual liver: state of the art and future perspectives. Arch Toxicol 2015; 88:2071-5. [PMID: 25331938 DOI: 10.1007/s00204-014-1384-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Dirk Drasdo
- Institut National de Recherche en Informatique et en Automatique (INRIA), Domaine de Voluceau - Rocquencourt, Paris, France
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35
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Zeigerer A, Bogorad RL, Sharma K, Gilleron J, Seifert S, Sales S, Berndt N, Bulik S, Marsico G, D'Souza RCJ, Lakshmanaperumal N, Meganathan K, Natarajan K, Sachinidis A, Dahl A, Holzhütter HG, Shevchenko A, Mann M, Koteliansky V, Zerial M. Regulation of liver metabolism by the endosomal GTPase Rab5. Cell Rep 2015; 11:884-892. [PMID: 25937276 DOI: 10.1016/j.celrep.2015.04.018] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 02/24/2015] [Accepted: 04/07/2015] [Indexed: 11/28/2022] Open
Abstract
The liver maintains glucose and lipid homeostasis by adapting its metabolic activity to the energy needs of the organism. Communication between hepatocytes and extracellular environment via endocytosis is key to such homeostasis. Here, we addressed the question of whether endosomes are required for gluconeogenic gene expression. We took advantage of the loss of endosomes in the mouse liver upon Rab5 silencing. Strikingly, we found hepatomegaly and severe metabolic defects such as hypoglycemia, hypercholesterolemia, hyperlipidemia, and glycogen accumulation that phenocopied those found in von Gierke's disease, a glucose-6-phosphatase (G6Pase) deficiency. G6Pase deficiency alone can account for the reduction in hepatic glucose output and glycogen accumulation as determined by mathematical modeling. Interestingly, we uncovered functional alterations in the transcription factors, which regulate G6Pase expression. Our data highlight a requirement of Rab5 and the endosomal system for the regulation of gluconeogenic gene expression that has important implications for metabolic diseases.
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Affiliation(s)
- Anja Zeigerer
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Roman L Bogorad
- David H. Koch Institute for Integrative Cancer Research, MIT, Cambridge, MA 02139, USA
| | - Kirti Sharma
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, 82152 Martinsried, Germany
| | - Jerome Gilleron
- INSERM U1065, Centre Méditerranéen de Médecine Moléculaire C3M, Université de Nice Sophia-Antipolis, 06108 Nice, France
| | - Sarah Seifert
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Susanne Sales
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | | | - Sascha Bulik
- Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Giovanni Marsico
- Cancer Research UK, Cambridge Institute, Li Ka Shing Centre, Cambridge CB2 0RE, UK
| | - Rochelle C J D'Souza
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, 82152 Martinsried, Germany
| | | | - Kesavan Meganathan
- University of Cologne, Institute of Neurophysiology and Center for Molecular Medicine Cologne (CMMC), 50931 Cologne, Germany
| | - Karthick Natarajan
- University of Cologne, Institute of Neurophysiology and Center for Molecular Medicine Cologne (CMMC), 50931 Cologne, Germany
| | - Agapios Sachinidis
- University of Cologne, Institute of Neurophysiology and Center for Molecular Medicine Cologne (CMMC), 50931 Cologne, Germany
| | - Andreas Dahl
- Deep Sequencing Group SFB655, BIOTEC, Technical University Dresden, 01307 Dresden, Germany
| | | | - Andrej Shevchenko
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, 82152 Martinsried, Germany
| | - Victor Koteliansky
- Skolkovo Institute of Science and Technology, ul. Novaya, d.100, Skolkovo 143025, Russian Federation; Lomonosov Moscow State University, Chemistry Department, Leninskie, Gory, 1/3, Moscow 119991, Russian Federation
| | - Marino Zerial
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
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Knüppel S, Meidtner K, Arregui M, Holzhütter HG, Boeing H. Joint Effect of Unlinked Genotypes: Application to Type 2 Diabetes in the EPIC-Potsdam Case-Cohort Study. Ann Hum Genet 2015; 79:253-63. [DOI: 10.1111/ahg.12115] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 03/04/2015] [Accepted: 02/24/2015] [Indexed: 02/03/2023]
Affiliation(s)
- Sven Knüppel
- Department of Epidemiology; German Institute of Human Nutrition Potsdam-Rehbruecke; 14558 Nuthetal Germany
| | - Karina Meidtner
- Department of Molecular Epidemiology; German Institute of Human Nutrition Potsdam-Rehbruecke; 14558 Nuthetal Germany
| | - Maria Arregui
- Research Group Cardiovascular Epidemiology; German Institute of Human Nutrition Potsdam-Rehbruecke; 14558 Nuthetal Germany
| | | | - Heiner Boeing
- Department of Epidemiology; German Institute of Human Nutrition Potsdam-Rehbruecke; 14558 Nuthetal Germany
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Palinkas A, Bulik S, Bockmayr A, Holzhütter HG. Sequential metabolic phases as a means to optimize cellular output in a constant environment. PLoS One 2015; 10:e0118347. [PMID: 25786979 PMCID: PMC4365075 DOI: 10.1371/journal.pone.0118347] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 01/14/2015] [Indexed: 11/25/2022] Open
Abstract
Temporal changes of gene expression are a well-known regulatory feature of all cells, which is commonly perceived as a strategy to adapt the proteome to varying external conditions. However, temporal (rhythmic and non-rhythmic) changes of gene expression are also observed under virtually constant external conditions. Here we hypothesize that such changes are a means to render the synthesis of the metabolic output more efficient than under conditions of constant gene activities. In order to substantiate this hypothesis, we used a flux-balance model of the cellular metabolism. The total time span spent on the production of a given set of target metabolites was split into a series of shorter time intervals (metabolic phases) during which only selected groups of metabolic genes are active. The related flux distributions were calculated under the constraint that genes can be either active or inactive whereby the amount of protein related to an active gene is only controlled by the number of active genes: the lower the number of active genes the more protein can be allocated to the enzymes carrying non-zero fluxes. This concept of a predominantly protein-limited efficiency of gene expression clearly differs from other concepts resting on the assumption of an optimal gene regulation capable of allocating to all enzymes and transporters just that fraction of protein necessary to prevent rate limitation. Applying this concept to a simplified metabolic network of the central carbon metabolism with glucose or lactate as alternative substrates, we demonstrate that switching between optimally chosen stationary flux modes comprising different sets of active genes allows producing a demanded amount of target metabolites in a significantly shorter time than by a single optimal flux mode at fixed gene activities. Our model-based findings suggest that temporal expression of metabolic genes can be advantageous even under conditions of constant external substrate supply.
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Affiliation(s)
- Aljoscha Palinkas
- FB Mathematik und Informatik, Freie Universität Berlin, Arnimallee 6, 14195 Berlin, Germany
- * E-mail:
| | - Sascha Bulik
- Institute of Biochemistry, University Medicine—Charite, Chariteplatz 1 Sitz: Virchowweg 6, 10117 Berlin, Germany
| | - Alexander Bockmayr
- FB Mathematik und Informatik, Freie Universität Berlin, Arnimallee 6, 14195 Berlin, Germany
| | - Hermann-Georg Holzhütter
- Institute of Biochemistry, University Medicine—Charite, Chariteplatz 1 Sitz: Virchowweg 6, 10117 Berlin, Germany
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Eckstein J, Berndt N, Holzhütter HG. Computer simulations suggest a key role of membranous nanodomains in biliary lipid secretion. PLoS Comput Biol 2015; 11:e1004033. [PMID: 25692493 PMCID: PMC4333117 DOI: 10.1371/journal.pcbi.1004033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 11/12/2014] [Indexed: 01/06/2023] Open
Abstract
The bile fluid contains various lipids that are secreted at the canalicular membrane of hepatocytes. As the secretion mechanism is still a matter of debate and a direct experimental observation of the secretion process is not possible so far, we used a mathematical model to simulate the extraction of the major bile lipids cholesterol, phosphatidylcholine and sphingomyelin from the outer leaflet of the canalicular membrane. Lipid diffusion was modeled as random movement on a triangular lattice governed by next-neighbor interaction energies. Phase separation in liquid-ordered and liquid-disordered domains was modeled by assigning two alternative ordering states to each lipid species and minimization of next-neighbor ordering energies. Parameterization of the model was performed such that experimentally determined diffusion rates and phases in ternary lipid mixtures of model membranes were correctly recapitulated. The model describes the spontaneous formation of nanodomains in the external leaflet of the canalicular membrane in a time window between 0.1 ms to 10 ms at varying lipid proportions. The extraction of lipid patches from the bile salt soluble nanodomain into the bile reproduced observed biliary phospholipid compositions for a physiologi-cal membrane composition. Comparing the outcome of model simulations with available experi-mental observations clearly favors the extraction of tiny membrane patches composed of about 100–400 lipids as the likely mechanism of biliary lipid secretion. Formation of the bile is one of the central functions of the liver. The bile fluid aids in the digestion of edible fats and removal of drugs and toxins from the body. The bile fluid is mainly composed of bile salts (BS), phosphatidylcholine (PC) and cholesterol (CH) in a fairly fixed proportion that prevents liver impairment by gallstone formation or cholestasis. During bile formation, BS are actively pumped out of the hepatocyte into the extracellular space where they extract PC and CH from the canalicular membrane. This extraction process bears the risk for the canalicular membrane to be destructed. Hence, only a certain fraction of the membrane should be accessible to the solubilizing activity of BS. We have developed a mathematical model that describes the temporal formation of CH-enriched ordered and PC-enriched disordered nanodomains in the canalicular membrane. Model simulations reveal that the disordered nanodomains exhibit a composition of PC and CH similar to that also found in the bile. From this finding and the good concordance of model simulations with experimental data we conclude that PC and CH are mainly secreted into the bile from the disordered nanodomain. Our work adds a new layer of physiological importance to the spontaneous formation of lipid domains in biological membranes.
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Affiliation(s)
- Johannes Eckstein
- Charité—University Medicine Berlin, Institute of Biochemistry, Berlin, Germany
| | - Nikolaus Berndt
- Charité—University Medicine Berlin, Institute of Biochemistry, Berlin, Germany
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Abstract
It is estimated that maintenance of the resting potential of neurons consumes between 15% (in gray matter) and 44% (in fully myelinated white matter) of the brain's total energy budget [1]. This poses the intriguing question why evolution has not strived to lower the permeability of passive ion channels to cut the high resting-state energy budget of the brain. Based on a conceptual mathematical model of neuronal ion currents and action potential (AP) firing we demonstrate that a neuron endowed with small leak currents and correspondingly low energy consumption by the Na(+)/K(+)-ATPase in the resting state may indeed recapitulate all features of normal AP firing. However, the activation and inactivation of such a "low-energy-cost neuron" turns out to be extremely sensitive to small fluctuation of Na(+) currents associated with Na(+)-dependent secondary-active transport that is indispensable for the metabolic integrity of the cell and neurotransmitter recycling. We provide evidence that sufficiently large leak currents function as important stabilizers of the membrane potential and thus are required to allow robust AP firing. Our simulations suggest that the energy demand of the Na(+)/K(+)-ATPase needed to counterbalance passive leak currents cannot be significantly dropped below observed values.
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Affiliation(s)
- Nikolaus Berndt
- Computational Biochemistry Group, Institute of Biochemistry, University Medicine Berlin (Charité), Charitéplatz 1/Sitz: Virchowweg 6, 10117, Berlin, Germany,
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Bölling C, Weidlich M, Holzhütter HG. SEE: structured representation of scientific evidence in the biomedical domain using Semantic Web techniques. J Biomed Semantics 2014; 5:S1. [PMID: 25093070 PMCID: PMC4108886 DOI: 10.1186/2041-1480-5-s1-s1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Accounts of evidence are vital to evaluate and reproduce scientific findings and integrate data on an informed basis. Currently, such accounts are often inadequate, unstandardized and inaccessible for computational knowledge engineering even though computational technologies, among them those of the semantic web, are ever more employed to represent, disseminate and integrate biomedical data and knowledge. RESULTS We present SEE (Semantic EvidencE), an RDF/OWL based approach for detailed representation of evidence in terms of the argumentative structure of the supporting background for claims even in complex settings. We derive design principles and identify minimal components for the representation of evidence. We specify the Reasoning and Discourse Ontology (RDO), an OWL representation of the model of scientific claims, their subjects, their provenance and their argumentative relations underlying the SEE approach. We demonstrate the application of SEE and illustrate its design patterns in a case study by providing an expressive account of the evidence for certain claims regarding the isolation of the enzyme glutamine synthetase. CONCLUSIONS SEE is suited to provide coherent and computationally accessible representations of evidence-related information such as the materials, methods, assumptions, reasoning and information sources used to establish a scientific finding by adopting a consistently claim-based perspective on scientific results and their evidence. SEE allows for extensible evidence representations, in which the level of detail can be adjusted and which can be extended as needed. It supports representation of arbitrary many consecutive layers of interpretation and attribution and different evaluations of the same data. SEE and its underlying model could be a valuable component in a variety of use cases that require careful representation or examination of evidence for data presented on the semantic web or in other formats.
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Affiliation(s)
- Christian Bölling
- Institute of Biochemistry, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Michael Weidlich
- Department of Computer Science, Humboldt-Universität zu Berlin, Berlin, Germany
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Hovestädt M, Kuckelkorn U, Niewienda A, Keller C, Goede A, Ay B, Günther S, Janek K, Volkmer R, Holzhütter HG. Rapid degradation of solid-phase bound peptides by the 20S proteasome. J Pept Sci 2013; 19:588-97. [DOI: 10.1002/psc.2536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 06/05/2013] [Accepted: 06/17/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Marc Hovestädt
- Mathematical Systems Biochemistry Group, Institute of Biochemistry; Charité - Universitätsmedizin Berlin; Berlin Germany
- Institute of Immunology; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Ulrike Kuckelkorn
- Proteolysis Group, Institute of Biochemistry; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Agathe Niewienda
- Proteolysis Group, Institute of Biochemistry; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Christin Keller
- Proteolysis Group, Institute of Biochemistry; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Andrean Goede
- Mathematical Systems Biochemistry Group, Institute of Biochemistry; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Bernhard Ay
- Institute of Immunology; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Stefan Günther
- Pharmaceutical Bioinformatics Group, Institute of Pharmaceutical Sciences; Albert-Ludwigs-University Freiburg; Freiburg Germany
| | - Katharina Janek
- Proteolysis Group, Institute of Biochemistry; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Rudolf Volkmer
- Institute of Immunology; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Hermann-Georg Holzhütter
- Mathematical Systems Biochemistry Group, Institute of Biochemistry; Charité - Universitätsmedizin Berlin; Berlin Germany
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Godoy P, Hewitt NJ, Albrecht U, Andersen ME, Ansari N, Bhattacharya S, Bode JG, Bolleyn J, Borner C, Böttger J, Braeuning A, Budinsky RA, Burkhardt B, Cameron NR, Camussi G, Cho CS, Choi YJ, Craig Rowlands J, Dahmen U, Damm G, Dirsch O, Donato MT, Dong J, Dooley S, Drasdo D, Eakins R, Ferreira KS, Fonsato V, Fraczek J, Gebhardt R, Gibson A, Glanemann M, Goldring CEP, Gómez-Lechón MJ, Groothuis GMM, Gustavsson L, Guyot C, Hallifax D, Hammad S, Hayward A, Häussinger D, Hellerbrand C, Hewitt P, Hoehme S, Holzhütter HG, Houston JB, Hrach J, Ito K, Jaeschke H, Keitel V, Kelm JM, Kevin Park B, Kordes C, Kullak-Ublick GA, LeCluyse EL, Lu P, Luebke-Wheeler J, Lutz A, Maltman DJ, Matz-Soja M, McMullen P, Merfort I, Messner S, Meyer C, Mwinyi J, Naisbitt DJ, Nussler AK, Olinga P, Pampaloni F, Pi J, Pluta L, Przyborski SA, Ramachandran A, Rogiers V, Rowe C, Schelcher C, Schmich K, Schwarz M, Singh B, Stelzer EHK, Stieger B, Stöber R, Sugiyama Y, Tetta C, Thasler WE, Vanhaecke T, Vinken M, Weiss TS, Widera A, Woods CG, Xu JJ, Yarborough KM, Hengstler JG. Recent advances in 2D and 3D in vitro systems using primary hepatocytes, alternative hepatocyte sources and non-parenchymal liver cells and their use in investigating mechanisms of hepatotoxicity, cell signaling and ADME. Arch Toxicol 2013; 87:1315-530. [PMID: 23974980 PMCID: PMC3753504 DOI: 10.1007/s00204-013-1078-5] [Citation(s) in RCA: 1042] [Impact Index Per Article: 94.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 05/06/2013] [Indexed: 12/15/2022]
Abstract
This review encompasses the most important advances in liver functions and hepatotoxicity and analyzes which mechanisms can be studied in vitro. In a complex architecture of nested, zonated lobules, the liver consists of approximately 80 % hepatocytes and 20 % non-parenchymal cells, the latter being involved in a secondary phase that may dramatically aggravate the initial damage. Hepatotoxicity, as well as hepatic metabolism, is controlled by a set of nuclear receptors (including PXR, CAR, HNF-4α, FXR, LXR, SHP, VDR and PPAR) and signaling pathways. When isolating liver cells, some pathways are activated, e.g., the RAS/MEK/ERK pathway, whereas others are silenced (e.g. HNF-4α), resulting in up- and downregulation of hundreds of genes. An understanding of these changes is crucial for a correct interpretation of in vitro data. The possibilities and limitations of the most useful liver in vitro systems are summarized, including three-dimensional culture techniques, co-cultures with non-parenchymal cells, hepatospheres, precision cut liver slices and the isolated perfused liver. Also discussed is how closely hepatoma, stem cell and iPS cell-derived hepatocyte-like-cells resemble real hepatocytes. Finally, a summary is given of the state of the art of liver in vitro and mathematical modeling systems that are currently used in the pharmaceutical industry with an emphasis on drug metabolism, prediction of clearance, drug interaction, transporter studies and hepatotoxicity. One key message is that despite our enthusiasm for in vitro systems, we must never lose sight of the in vivo situation. Although hepatocytes have been isolated for decades, the hunt for relevant alternative systems has only just begun.
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Affiliation(s)
- Patricio Godoy
- Leibniz Research Centre for Working Environment and Human Factors (IFADO), 44139 Dortmund, Germany
| | | | - Ute Albrecht
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University, Moorenstrasse 5, 40225 Düsseldorf, Germany
| | - Melvin E. Andersen
- The Hamner Institutes for Health Sciences, Research Triangle Park, NC USA
| | - Nariman Ansari
- Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University Frankfurt, Max-von-Laue-Str. 15, 60438 Frankfurt am Main, Germany
| | - Sudin Bhattacharya
- The Hamner Institutes for Health Sciences, Research Triangle Park, NC USA
| | - Johannes Georg Bode
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University, Moorenstrasse 5, 40225 Düsseldorf, Germany
| | - Jennifer Bolleyn
- Department of Toxicology, Centre for Pharmaceutical Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, 1090 Brussels, Belgium
| | - Christoph Borner
- Institute of Molecular Medicine and Cell Research, University of Freiburg, Freiburg, Germany
| | - Jan Böttger
- Institute of Biochemistry, Faculty of Medicine, University of Leipzig, 04103 Leipzig, Germany
| | - Albert Braeuning
- Department of Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Wilhelmstr. 56, 72074 Tübingen, Germany
| | - Robert A. Budinsky
- Toxicology and Environmental Research and Consulting, The Dow Chemical Company, Midland, MI USA
| | - Britta Burkhardt
- BG Trauma Center, Siegfried Weller Institut, Eberhard Karls University Tübingen, 72076 Tübingen, Germany
| | - Neil R. Cameron
- Department of Chemistry, Durham University, Durham, DH1 3LE UK
| | - Giovanni Camussi
- Department of Medical Sciences, University of Torino, 10126 Turin, Italy
| | - Chong-Su Cho
- Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, 151-921 Korea
| | - Yun-Jaie Choi
- Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, 151-921 Korea
| | - J. Craig Rowlands
- Toxicology and Environmental Research and Consulting, The Dow Chemical Company, Midland, MI USA
| | - Uta Dahmen
- Experimental Transplantation Surgery, Department of General Visceral, and Vascular Surgery, Friedrich-Schiller-University Jena, 07745 Jena, Germany
| | - Georg Damm
- Department of General-, Visceral- and Transplantation Surgery, Charité University Medicine Berlin, 13353 Berlin, Germany
| | - Olaf Dirsch
- Institute of Pathology, Friedrich-Schiller-University Jena, 07745 Jena, Germany
| | - María Teresa Donato
- Unidad de Hepatología Experimental, IIS Hospital La Fe Avda Campanar 21, 46009 Valencia, Spain
- CIBERehd, Fondo de Investigaciones Sanitarias, Barcelona, Spain
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Valencia, Valencia, Spain
| | - Jian Dong
- The Hamner Institutes for Health Sciences, Research Triangle Park, NC USA
| | - Steven Dooley
- Department of Medicine II, Section Molecular Hepatology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Dirk Drasdo
- Interdisciplinary Center for Bioinformatics (IZBI), University of Leipzig, 04107 Leipzig, Germany
- INRIA (French National Institute for Research in Computer Science and Control), Domaine de Voluceau-Rocquencourt, B.P. 105, 78153 Le Chesnay Cedex, France
- UPMC University of Paris 06, CNRS UMR 7598, Laboratoire Jacques-Louis Lions, 4, pl. Jussieu, 75252 Paris cedex 05, France
| | - Rowena Eakins
- Department of Molecular and Clinical Pharmacology, Centre for Drug Safety Science, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - Karine Sá Ferreira
- Institute of Molecular Medicine and Cell Research, University of Freiburg, Freiburg, Germany
- GRK 1104 From Cells to Organs, Molecular Mechanisms of Organogenesis, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Valentina Fonsato
- Department of Medical Sciences, University of Torino, 10126 Turin, Italy
| | - Joanna Fraczek
- Department of Toxicology, Centre for Pharmaceutical Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, 1090 Brussels, Belgium
| | - Rolf Gebhardt
- Institute of Biochemistry, Faculty of Medicine, University of Leipzig, 04103 Leipzig, Germany
| | - Andrew Gibson
- Department of Molecular and Clinical Pharmacology, Centre for Drug Safety Science, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - Matthias Glanemann
- Department of General-, Visceral- and Transplantation Surgery, Charité University Medicine Berlin, 13353 Berlin, Germany
| | - Chris E. P. Goldring
- Department of Molecular and Clinical Pharmacology, Centre for Drug Safety Science, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - María José Gómez-Lechón
- Unidad de Hepatología Experimental, IIS Hospital La Fe Avda Campanar 21, 46009 Valencia, Spain
- CIBERehd, Fondo de Investigaciones Sanitarias, Barcelona, Spain
| | - Geny M. M. Groothuis
- Department of Pharmacy, Pharmacokinetics Toxicology and Targeting, University of Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Lena Gustavsson
- Department of Laboratory Medicine (Malmö), Center for Molecular Pathology, Lund University, Jan Waldenströms gata 59, 205 02 Malmö, Sweden
| | - Christelle Guyot
- Department of Clinical Pharmacology and Toxicology, University Hospital, 8091 Zurich, Switzerland
| | - David Hallifax
- Centre for Applied Pharmacokinetic Research (CAPKR), School of Pharmacy and Pharmaceutical Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT UK
| | - Seddik Hammad
- Department of Forensic Medicine and Veterinary Toxicology, Faculty of Veterinary Medicine, South Valley University, Qena, Egypt
| | - Adam Hayward
- Biological and Biomedical Sciences, Durham University, Durham, DH13LE UK
| | - Dieter Häussinger
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University, Moorenstrasse 5, 40225 Düsseldorf, Germany
| | - Claus Hellerbrand
- Department of Medicine I, University Hospital Regensburg, 93053 Regensburg, Germany
| | | | - Stefan Hoehme
- Interdisciplinary Center for Bioinformatics (IZBI), University of Leipzig, 04107 Leipzig, Germany
| | - Hermann-Georg Holzhütter
- Institut für Biochemie Abteilung Mathematische Systembiochemie, Universitätsmedizin Berlin (Charité), Charitéplatz 1, 10117 Berlin, Germany
| | - J. Brian Houston
- Centre for Applied Pharmacokinetic Research (CAPKR), School of Pharmacy and Pharmaceutical Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT UK
| | | | - Kiyomi Ito
- Research Institute of Pharmaceutical Sciences, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585 Japan
| | - Hartmut Jaeschke
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160 USA
| | - Verena Keitel
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University, Moorenstrasse 5, 40225 Düsseldorf, Germany
| | | | - B. Kevin Park
- Department of Molecular and Clinical Pharmacology, Centre for Drug Safety Science, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - Claus Kordes
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University, Moorenstrasse 5, 40225 Düsseldorf, Germany
| | - Gerd A. Kullak-Ublick
- Department of Clinical Pharmacology and Toxicology, University Hospital, 8091 Zurich, Switzerland
| | - Edward L. LeCluyse
- The Hamner Institutes for Health Sciences, Research Triangle Park, NC USA
| | - Peng Lu
- The Hamner Institutes for Health Sciences, Research Triangle Park, NC USA
| | | | - Anna Lutz
- Department of Pharmaceutical Biology and Biotechnology, University of Freiburg, Freiburg, Germany
| | - Daniel J. Maltman
- Reinnervate Limited, NETPark Incubator, Thomas Wright Way, Sedgefield, TS21 3FD UK
| | - Madlen Matz-Soja
- Institute of Biochemistry, Faculty of Medicine, University of Leipzig, 04103 Leipzig, Germany
| | - Patrick McMullen
- The Hamner Institutes for Health Sciences, Research Triangle Park, NC USA
| | - Irmgard Merfort
- Department of Pharmaceutical Biology and Biotechnology, University of Freiburg, Freiburg, Germany
| | | | - Christoph Meyer
- Department of Medicine II, Section Molecular Hepatology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Jessica Mwinyi
- Department of Clinical Pharmacology and Toxicology, University Hospital, 8091 Zurich, Switzerland
| | - Dean J. Naisbitt
- Department of Molecular and Clinical Pharmacology, Centre for Drug Safety Science, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - Andreas K. Nussler
- BG Trauma Center, Siegfried Weller Institut, Eberhard Karls University Tübingen, 72076 Tübingen, Germany
| | - Peter Olinga
- Division of Pharmaceutical Technology and Biopharmacy, Department of Pharmacy, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Francesco Pampaloni
- Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University Frankfurt, Max-von-Laue-Str. 15, 60438 Frankfurt am Main, Germany
| | - Jingbo Pi
- The Hamner Institutes for Health Sciences, Research Triangle Park, NC USA
| | - Linda Pluta
- The Hamner Institutes for Health Sciences, Research Triangle Park, NC USA
| | - Stefan A. Przyborski
- Reinnervate Limited, NETPark Incubator, Thomas Wright Way, Sedgefield, TS21 3FD UK
- Biological and Biomedical Sciences, Durham University, Durham, DH13LE UK
| | - Anup Ramachandran
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160 USA
| | - Vera Rogiers
- Department of Toxicology, Centre for Pharmaceutical Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, 1090 Brussels, Belgium
| | - Cliff Rowe
- Department of Molecular and Clinical Pharmacology, Centre for Drug Safety Science, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - Celine Schelcher
- Department of Surgery, Liver Regeneration, Core Facility, Human in Vitro Models of the Liver, Ludwig Maximilians University of Munich, Munich, Germany
| | - Kathrin Schmich
- Department of Pharmaceutical Biology and Biotechnology, University of Freiburg, Freiburg, Germany
| | - Michael Schwarz
- Department of Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Wilhelmstr. 56, 72074 Tübingen, Germany
| | - Bijay Singh
- Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, 151-921 Korea
| | - Ernst H. K. Stelzer
- Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University Frankfurt, Max-von-Laue-Str. 15, 60438 Frankfurt am Main, Germany
| | - Bruno Stieger
- Department of Clinical Pharmacology and Toxicology, University Hospital, 8091 Zurich, Switzerland
| | - Regina Stöber
- Leibniz Research Centre for Working Environment and Human Factors (IFADO), 44139 Dortmund, Germany
| | - Yuichi Sugiyama
- Sugiyama Laboratory, RIKEN Innovation Center, RIKEN, Yokohama Biopharmaceutical R&D Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045 Japan
| | - Ciro Tetta
- Fresenius Medical Care, Bad Homburg, Germany
| | - Wolfgang E. Thasler
- Department of Surgery, Ludwig-Maximilians-University of Munich Hospital Grosshadern, Munich, Germany
| | - Tamara Vanhaecke
- Department of Toxicology, Centre for Pharmaceutical Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, 1090 Brussels, Belgium
| | - Mathieu Vinken
- Department of Toxicology, Centre for Pharmaceutical Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, 1090 Brussels, Belgium
| | - Thomas S. Weiss
- Department of Pediatrics and Juvenile Medicine, University of Regensburg Hospital, Regensburg, Germany
| | - Agata Widera
- Leibniz Research Centre for Working Environment and Human Factors (IFADO), 44139 Dortmund, Germany
| | - Courtney G. Woods
- The Hamner Institutes for Health Sciences, Research Triangle Park, NC USA
| | | | | | - Jan G. Hengstler
- Leibniz Research Centre for Working Environment and Human Factors (IFADO), 44139 Dortmund, Germany
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Knüppel S, Rohde K, Meidtner K, Drogan D, Holzhütter HG, Boeing H, Fisher E. Evaluation of 41 candidate gene variants for obesity in the EPIC-Potsdam cohort by multi-locus stepwise regression. PLoS One 2013; 8:e68941. [PMID: 23874820 PMCID: PMC3709896 DOI: 10.1371/journal.pone.0068941] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Accepted: 06/04/2013] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVE Obesity has become a leading preventable cause of morbidity and mortality in many parts of the world. It is thought to originate from multiple genetic and environmental determinants. The aim of the current study was to introduce haplotype-based multi-locus stepwise regression (MSR) as a method to investigate combinations of unlinked single nucleotide polymorphisms (SNPs) for obesity phenotypes. METHODS In 2,122 healthy randomly selected men and women of the EPIC-Potsdam cohort, the association between 41 SNPs from 18 obesity-candidate genes and either body mass index (BMI, mean=25.9 kg/m(2), SD=4.1) or waist circumference (WC, mean=85.2 cm, SD=12.6) was assessed. Single SNP analyses were done by using linear regression adjusted for age, sex, and other covariates. Subsequently, MSR was applied to search for the 'best' SNP combinations. Combinations were selected according to specific AICc and p-value criteria. Model uncertainty was accounted for by a permutation test. RESULTS The strongest single SNP effects on BMI were found for TBC1D1 rs637797 (β = -0.33, SE=0.13), FTO rs9939609 (β=0.28, SE=0.13), MC4R rs17700144 (β=0.41, SE=0.15), and MC4R rs10871777 (β=0.34, SE=0.14). All these SNPs showed similar effects on waist circumference. The two 'best' six-SNP combinations for BMI (global p-value= 3.45⋅10(-6) and 6.82⋅10(-6)) showed effects ranging from -1.70 (SE=0.34) to 0.74 kg/m(2) (SE=0.21) per allele combination. We selected two six-SNP combinations on waist circumference (global p-value = 7.80⋅10(-6) and 9.76⋅10(-6)) with an allele combination effect of -2.96 cm (SE=0.76) at maximum. Additional adjustment for BMI revealed 15 three-SNP combinations (global p-values ranged from 3.09⋅10(-4) to 1.02⋅10(-2)). However, after carrying out the permutation test all SNP combinations lost significance indicating that the statistical associations might have occurred by chance. CONCLUSION MSR provides a tool to search for risk-related SNP combinations of common traits or diseases. However, the search process does not always find meaningful SNP combinations in a dataset.
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Affiliation(s)
- Sven Knüppel
- Department of Epidemiology, German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal, Germany.
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König M, Holzhütter HG, Berndt N. Metabolic gradients as key regulators in zonation of tumor energy metabolism: A tissue-scale model-based study. Biotechnol J 2013; 8:1058-69. [DOI: 10.1002/biot.201200393] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 02/04/2013] [Accepted: 04/15/2013] [Indexed: 01/08/2023]
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Huchzermeyer C, Berndt N, Holzhütter HG, Kann O. Oxygen consumption rates during three different neuronal activity states in the hippocampal CA3 network. J Cereb Blood Flow Metab 2013; 33:263-71. [PMID: 23168532 PMCID: PMC3564197 DOI: 10.1038/jcbfm.2012.165] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 09/05/2012] [Accepted: 10/15/2012] [Indexed: 01/09/2023]
Abstract
The brain is an organ with high metabolic rate. However, little is known about energy utilization during different activity states of neuronal networks. We addressed this issue in area CA3 of hippocampal slice cultures under well-defined recording conditions using a 20% O(2) gas mixture. We combined recordings of local field potential and interstitial partial oxygen pressure (pO(2)) during three different activity states, namely fast network oscillations in the gamma-frequency band (30 to 100 Hz), spontaneous network activity and absence of spiking (action potentials). Oxygen consumption rates were determined by pO(2) depth profiles with high spatial resolution and a mathematical model that considers convective transport, diffusion, and activity-dependent consumption of oxygen. We show that: (1) Relative oxygen consumption rate during cholinergic gamma oscillations was 2.2-fold and 5.3-fold higher compared with spontaneous activity and absence of spiking, respectively. (2) Gamma oscillations were associated with a similar large decrease in pO(2) as observed previously with a 95% O(2) gas mixture. (3) Sufficient oxygenation during fast network oscillations in vivo is ensured by the calculated critical radius of 30 to 40 μm around a capillary. We conclude that the structural and biophysical features of brain tissue permit variations in local oxygen consumption by a factor of about five.
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Affiliation(s)
| | - Nikolaus Berndt
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | | | - Oliver Kann
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
- Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
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Hoppe A, Ilkavets I, Dooley S, Holzhütter HG. Metabolic Consequences of TGFb Stimulation in CulturedPrimary Mouse Hepatocytes Screened from Transcript Data with ModeScore . Metabolites 2012; 2:983-1003. [PMID: 24957771 PMCID: PMC3901234 DOI: 10.3390/metabo2040983] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 10/18/2012] [Accepted: 11/07/2012] [Indexed: 12/31/2022] Open
Abstract
TGFβ signaling plays a major role in the reorganization of liver tissue upon injury and is an important driver of chronic liver disease. This is achieved by a deep impact on a cohort of cellular functions. To comprehensively assess the full range of affected metabolic functions, transcript changes of cultured mouse hepatocytes were analyzed with a novel method (ModeScore), which predicts the activity of metabolic functions by scoring transcript expression changes with 987 reference flux distributions, which yielded the following hypotheses. TGFβ multiplies down-regulation of most metabolic functions occurring in culture stressed controls. This is especially pronounced for tyrosine degradation, urea synthesis, glucuronization capacity, and cholesterol synthesis. Ethanol degradation and creatine synthesis are down-regulated only in TGFβ treated hepatocytes, but not in the control. Among the few TGFβ dependently up-regulated functions, synthesis of various collagens is most pronounced. Further interesting findings include: down-regulation of glucose export is postponed by TGFβ, TGFβ up-regulates the synthesis capacity of ketone bodies only as an early response, TGFβ suppresses the strong up-regulation of Vanin, and TGFβ induces re-formation of ceramides and sphingomyelin.
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Affiliation(s)
- Andreas Hoppe
- Institute for Biochemistry, Charité University Medicine Berlin, Charitéplatz 1/Virchowweg 6, 10117 Berlin, Germany.
| | - Iryna Ilkavets
- Molecular Hepatology and Alcohol Associated Diseases, Medical Clinic II, Medical Faculty Mannheim at Heidelberg University, Theodor-Kutzer-Ufer 1-3, H42 E4, 68167 Mannheim, Germany.
| | - Steven Dooley
- Molecular Hepatology and Alcohol Associated Diseases, Medical Clinic II, Medical Faculty Mannheim at Heidelberg University, Theodor-Kutzer-Ufer 1-3, H42 E4, 68167 Mannheim, Germany.
| | - Hermann-Georg Holzhütter
- Institute for Biochemistry, Charité University Medicine Berlin, Charitéplatz 1/Virchowweg 6, 10117 Berlin, Germany.
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König M, Holzhütter HG. Kinetic modeling of human hepatic glucose metabolism in type 2 diabetes mellitus predicts higher risk of hypoglycemic events in rigorous insulin therapy. J Biol Chem 2012; 287:36978-89. [PMID: 22977253 DOI: 10.1074/jbc.m112.382069] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A major problem in the insulin therapy of patients with diabetes type 2 (T2DM) is the increased occurrence of hypoglycemic events which, if left untreated, may cause confusion or fainting and in severe cases seizures, coma, and even death. To elucidate the potential contribution of the liver to hypoglycemia in T2DM we applied a detailed kinetic model of human hepatic glucose metabolism to simulate changes in glycolysis, gluconeogenesis, and glycogen metabolism induced by deviations of the hormones insulin, glucagon, and epinephrine from their normal plasma profiles. Our simulations reveal in line with experimental and clinical data from a multitude of studies in T2DM, (i) significant changes in the relative contribution of glycolysis, gluconeogenesis, and glycogen metabolism to hepatic glucose production and hepatic glucose utilization; (ii) decreased postprandial glycogen storage as well as increased glycogen depletion in overnight fasting and short term fasting; and (iii) a shift of the set point defining the switch between hepatic glucose production and hepatic glucose utilization to elevated plasma glucose levels, respectively, in T2DM relative to normal, healthy subjects. Intriguingly, our model simulations predict a restricted gluconeogenic response of the liver under impaired hormonal signals observed in T2DM, resulting in an increased risk of hypoglycemia. The inability of hepatic glucose metabolism to effectively counterbalance a decline of the blood glucose level becomes even more pronounced in case of tightly controlled insulin treatment. Given this Janus face mode of action of insulin, our model simulations underline the great potential that normalization of the plasma glucagon profile may have for the treatment of T2DM.
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Affiliation(s)
- Matthias König
- Institute of Biochemistry, University Medicine Charité Berlin, 10117 Berlin, Germany.
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Bazzani S, Hoppe A, Holzhütter HG. Network-based assessment of the selectivity of metabolic drug targets in Plasmodium falciparum with respect to human liver metabolism. BMC Syst Biol 2012; 6:118. [PMID: 22937810 PMCID: PMC3543272 DOI: 10.1186/1752-0509-6-118] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 07/23/2012] [Indexed: 11/10/2022]
Abstract
Background The search for new drug targets for antibiotics against Plasmodium falciparum, a major cause of human deaths, is a pressing scientific issue, as multiple resistance strains spread rapidly. Metabolic network-based analyses may help to identify those parasite’s essential enzymes whose homologous counterparts in the human host cells are either absent, non-essential or relatively less essential. Results Using the well-curated metabolic networks PlasmoNet of the parasite Plasmodium falciparum and HepatoNet1 of the human hepatocyte, the selectivity of 48 experimental antimalarial drug targets was analyzed. Applying in silico gene deletions, 24 of these drug targets were found to be perfectly selective, in that they were essential for the parasite but non-essential for the human cell. The selectivity of a subset of enzymes, that were essential in both models, was evaluated with the reduced fitness concept. It was, then, possible to quantify the reduction in functional fitness of the two networks under the progressive inhibition of the same enzymatic activity. Overall, this in silico analysis provided a selectivity ranking that was in line with numerous in vivo and in vitro observations. Conclusions Genome-scale models can be useful to depict and quantify the effects of enzymatic inhibitions on the impaired production of biomass components. From the perspective of a host-pathogen metabolic interaction, an estimation of the drug targets-induced consequences can be beneficial for the development of a selective anti-parasitic drug.
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Affiliation(s)
- Susanna Bazzani
- Institut für Biochemie, Charite-Universitätsmedizin, Berlin, Germany.
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Karlstädt A, Fliegner D, Kararigas G, Ruderisch HS, Regitz-Zagrosek V, Holzhütter HG. CardioNet: a human metabolic network suited for the study of cardiomyocyte metabolism. BMC Syst Biol 2012; 6:114. [PMID: 22929619 PMCID: PMC3568067 DOI: 10.1186/1752-0509-6-114] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2012] [Accepted: 08/16/2012] [Indexed: 02/08/2023]
Abstract
Background Availability of oxygen and nutrients in the coronary circulation is a crucial determinant of cardiac performance. Nutrient composition of coronary blood may significantly vary in specific physiological and pathological conditions, for example, administration of special diets, long-term starvation, physical exercise or diabetes. Quantitative analysis of cardiac metabolism from a systems biology perspective may help to a better understanding of the relationship between nutrient supply and efficiency of metabolic processes required for an adequate cardiac output. Results Here we present CardioNet, the first large-scale reconstruction of the metabolic network of the human cardiomyocyte comprising 1793 metabolic reactions, including 560 transport processes in six compartments. We use flux-balance analysis to demonstrate the capability of the network to accomplish a set of 368 metabolic functions required for maintaining the structural and functional integrity of the cell. Taking the maintenance of ATP, biosynthesis of ceramide, cardiolipin and further important phospholipids as examples, we analyse how a changed supply of glucose, lactate, fatty acids and ketone bodies may influence the efficiency of these essential processes. Conclusions CardioNet is a functionally validated metabolic network of the human cardiomyocyte that enables theorectical studies of cellular metabolic processes crucial for the accomplishment of an adequate cardiac output.
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Affiliation(s)
- Anja Karlstädt
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Charitéplatz 1/Virchowweg 6, 10117 Berlin, Germany.
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Abstract
SUMMARY CySBML is a plugin designed to work with Systems Biology Markup Language (SBML) in Cytoscape having the following features: SBML import, support of the SBML layout and qualitative model packages, navigation in network layouts based on SBML structure, access to MIRIAM and SBO-based annotations and SBML validation. CySBML includes an importer for BioModels to load SBML from standard repositories. AVAILABILITY AND IMPLEMENTATION Freely available for non-commercial purposes through the Cytoscape plugin manager or for download at http://sourceforge.net/projects/cysbml/. CONTACT cysbml-team@lists.sourceforge.net SUPPLEMENTARY INFORMATION Tutorial, usage guide, installation instructions and additional figures are available for download at http://www.charite.de/sysbio/people/koenig/software/cysbml/.
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Affiliation(s)
- Matthias König
- Department of Biochemistry, University Medicine Charité Berlin, 13347, Berlin, Germany.
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