1
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Luo J, Zhu WC, Chen QX, Yang CF, Huang BJ, Zhang SJ. A prognostic model based on DNA methylation-related gene expression for predicting overall survival in hepatocellular carcinoma. Front Oncol 2024; 13:1171932. [PMID: 38304027 PMCID: PMC10830715 DOI: 10.3389/fonc.2023.1171932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 12/27/2023] [Indexed: 02/03/2024] Open
Abstract
Background Hepatocellular carcinoma (HCC) continues to increase in morbidity and mortality among all types of cancer. DNA methylation, an important epigenetic modification, is associated with cancer occurrence and progression. The objective of this study was to establish a model based on DNA methylation risk scores for identifying new potential therapeutic targets in HCC and preventing cancer progression. Methods Transcriptomic, clinical, and DNA methylation data on 374 tumor tissues and 50 adjacent normal tissues were downloaded from The Cancer Genome Atlas-Liver Hepatocellular Carcinoma database. The gene expression profiles of the GSE54236 liver cancer dataset, which contains data on 161 liver tissue samples, were obtained from the Gene Expression Omnibus database. We analyzed the relationship between DNA methylation and gene expression levels after identifying the differentially methylated and expressed genes. Then, we developed and validated a risk score model based on the DNA methylation-driven genes. A tissue array consisting of 30 human hepatocellular carcinoma samples and adjacent normal tissues was used to assess the protein and mRNA expression levels of the marker genes by immunohistochemistry and qRT-PCR, respectively. Results Three methylation-related differential genes were identified in our study: GLS, MEX3B, and GNA14. The results revealed that their DNA methylation levels were negatively correlated with local gene expression regulation. The gene methylation levels correlated strongly with the prognosis of patients with liver cancer. This was confirmed by qRT-PCR and immunohistochemical verification of the expression of these genes or proteins in tumors and adjacent tissues. These results revealed the relationship between the level of relevant gene methylation and the prognosis of patients with liver cancer as well as the underlying cellular and biological mechanisms. This allows our gene signature to provide more accurate and appropriate predictions for clinical applications. Conclusion Through bioinformatics analysis and experimental validation, we obtained three DNA methylation marker: GLS, MEX3B, and GNA14. This helps to predict the prognosis and may be a potential therapeutic target for HCC patients.
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Affiliation(s)
- Jin Luo
- Department of Traditional Chinese Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Department of Traditional Chinese Medicine, Shenzhen Children’s Hospital, Shenzhen, Guangdong, China
| | - Wan-Cui Zhu
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China
| | - Qiu-Xia Chen
- Department of Traditional Chinese Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Chang-Fu Yang
- Department of Oncology, The People’s Hospital of Gaozhou, Gaozhou, China
| | - Bi-Jun Huang
- Department of Experimental Research, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Shi-Jun Zhang
- Department of Traditional Chinese Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
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2
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Singh C, Tran V, McCollum L, Bolok Y, Allan K, Yuan A, Hoppe G, Brunengraber H, Sears JE. Hyperoxia induces glutamine-fuelled anaplerosis in retinal Müller cells. Nat Commun 2020; 11:1277. [PMID: 32152301 PMCID: PMC7062830 DOI: 10.1038/s41467-020-15066-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 02/17/2020] [Indexed: 01/03/2023] Open
Abstract
Although supplemental oxygen is required to promote survival of severely premature infants, hyperoxia is simultaneously harmful to premature developing tissues such as in the retina. Here we report the effect of hyperoxia on central carbon metabolism in primary mouse Müller glial cells and a human Müller glia cell line (M10-M1 cells). We found decreased flux from glycolysis entering the tricarboxylic acid cycle in Müller cells accompanied by increased glutamine consumption in response to hyperoxia. In hyperoxia, anaplerotic catabolism of glutamine by Müller cells increased ammonium release two-fold. Hyperoxia induces glutamine-fueled anaplerosis that reverses basal Müller cell metabolism from production to consumption of glutamine. Prematurely born babies need extra oxygen to survive, but this can cause damage to the eyes and lead to infant blindness. Here the authors show that this hyperoxia changes the metabolism of Müller cells in the retina such that they use up, rather than produce, glutamine and secrete excess ammonium.
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Affiliation(s)
- Charandeep Singh
- Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Vincent Tran
- Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Leah McCollum
- Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Youstina Bolok
- Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Kristin Allan
- Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.,Molecular Medicine, Case Western Reserve School of Medicine Cleveland, Cleveland, OH, 44106, USA
| | - Alex Yuan
- Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - George Hoppe
- Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Henri Brunengraber
- Department of Nutrition, Case Western Reserve School of Medicine Cleveland, Cleveland, OH, 44106, USA
| | - Jonathan E Sears
- Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA. .,Cardiovascular and Metabolic Sciences, Cleveland Clinic, Cleveland, OH, 44195, USA.
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3
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Huang H, Vandekeere S, Kalucka J, Bierhansl L, Zecchin A, Brüning U, Visnagri A, Yuldasheva N, Goveia J, Cruys B, Brepoels K, Wyns S, Rayport S, Ghesquière B, Vinckier S, Schoonjans L, Cubbon R, Dewerchin M, Eelen G, Carmeliet P. Role of glutamine and interlinked asparagine metabolism in vessel formation. EMBO J 2017; 36:2334-2352. [PMID: 28659375 DOI: 10.15252/embj.201695518] [Citation(s) in RCA: 187] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 06/07/2017] [Accepted: 06/08/2017] [Indexed: 12/31/2022] Open
Abstract
Endothelial cell (EC) metabolism is emerging as a regulator of angiogenesis, but the precise role of glutamine metabolism in ECs is unknown. Here, we show that depriving ECs of glutamine or inhibiting glutaminase 1 (GLS1) caused vessel sprouting defects due to impaired proliferation and migration, and reduced pathological ocular angiogenesis. Inhibition of glutamine metabolism in ECs did not cause energy distress, but impaired tricarboxylic acid (TCA) cycle anaplerosis, macromolecule production, and redox homeostasis. Only the combination of TCA cycle replenishment plus asparagine supplementation restored the metabolic aberrations and proliferation defect caused by glutamine deprivation. Mechanistically, glutamine provided nitrogen for asparagine synthesis to sustain cellular homeostasis. While ECs can take up asparagine, silencing asparagine synthetase (ASNS, which converts glutamine-derived nitrogen and aspartate to asparagine) impaired EC sprouting even in the presence of glutamine and asparagine. Asparagine further proved crucial in glutamine-deprived ECs to restore protein synthesis, suppress ER stress, and reactivate mTOR signaling. These findings reveal a novel link between endothelial glutamine and asparagine metabolism in vessel sprouting.
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Affiliation(s)
- Hongling Huang
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Saar Vandekeere
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Joanna Kalucka
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Laura Bierhansl
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Annalisa Zecchin
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Ulrike Brüning
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Asjad Visnagri
- Leeds Institute of Cardiovascular & Metabolic Medicine, The University of Leeds, Leeds, UK
| | - Nadira Yuldasheva
- Leeds Institute of Cardiovascular & Metabolic Medicine, The University of Leeds, Leeds, UK
| | - Jermaine Goveia
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Bert Cruys
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Katleen Brepoels
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Sabine Wyns
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Stephen Rayport
- Department of Psychiatry, Columbia University, New York, NY, USA.,Department of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, USA
| | - Bart Ghesquière
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Stefan Vinckier
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Luc Schoonjans
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Richard Cubbon
- Leeds Institute of Cardiovascular & Metabolic Medicine, The University of Leeds, Leeds, UK
| | - Mieke Dewerchin
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Guy Eelen
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
| | - Peter Carmeliet
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven, Leuven, Belgium .,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, VIB, Leuven, Belgium
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4
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Caja S, Enríquez JA. Mitochondria in endothelial cells: Sensors and integrators of environmental cues. Redox Biol 2017; 12:821-827. [PMID: 28448943 PMCID: PMC5406579 DOI: 10.1016/j.redox.2017.04.021] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Revised: 03/23/2017] [Accepted: 04/13/2017] [Indexed: 12/19/2022] Open
Abstract
The involvement of angiogenesis in disease and its potential as a therapeutic target have been firmly established over recent decades. Endothelial cells (ECs) are central elements in vessel homeostasis and regulate the passage of material and cells into and out of the bloodstream. EC proliferation and migration are modified by alterations to mitochondrial biogenesis and dynamics resulting from several signals and environmental cues, such as oxygen, hemodynamics, and nutrients. As intermediary signals, mitochondrial ROS are released as important downstream modulators of the expression of angiogenesis-related genes. In this review, we discuss the physiological actions of these signals and aberrant responses during vascular disorders. Mitochondria in EC act as integrators of environmental cues. Circulating signals modify mitochondrial dynamics, altering EC phenotype. ROS release by EC mitochondria regulates expression of vascular genes.
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Affiliation(s)
- Sergio Caja
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Jose Antonio Enríquez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain; Centro de Investigaciones en RED (CIBERFES), Melchor Fernández Almagro, 28029 Madrid, Spain.
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5
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McGarrity S, Halldórsson H, Palsson S, Johansson PI, Rolfsson Ó. Understanding the Causes and Implications of Endothelial Metabolic Variation in Cardiovascular Disease through Genome-Scale Metabolic Modeling. Front Cardiovasc Med 2016; 3:10. [PMID: 27148541 PMCID: PMC4834436 DOI: 10.3389/fcvm.2016.00010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 04/03/2016] [Indexed: 01/04/2023] Open
Abstract
High-throughput biochemical profiling has led to a requirement for advanced data interpretation techniques capable of integrating the analysis of gene, protein, and metabolic profiles to shed light on genotype-phenotype relationships. Herein, we consider the current state of knowledge of endothelial cell (EC) metabolism and its connections to cardiovascular disease (CVD) and explore the use of genome-scale metabolic models (GEMs) for integrating metabolic and genomic data. GEMs combine gene expression and metabolic data acting as frameworks for their analysis and, ultimately, afford mechanistic understanding of how genetic variation impacts metabolism. We demonstrate how GEMs can be used to investigate CVD-related genetic variation, drug resistance mechanisms, and novel metabolic pathways in ECs. The application of GEMs in personalized medicine is also highlighted. Particularly, we focus on the potential of GEMs to identify metabolic biomarkers of endothelial dysfunction and to discover methods of stratifying treatments for CVDs based on individual genetic markers. Recent advances in systems biology methodology, and how these methodologies can be applied to understand EC metabolism in both health and disease, are thus highlighted.
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Affiliation(s)
- Sarah McGarrity
- Center for Systems Biology, University of Iceland , Reykjavik , Iceland
| | - Haraldur Halldórsson
- Department of Pharmacology and Toxicology, School of Health Sciences, University of Iceland , Reykjavik , Iceland
| | - Sirus Palsson
- Center for Systems Biology, University of Iceland, Reykjavik, Iceland; Sinopia Biosciences Inc., San Diego, CA, USA
| | - Pär I Johansson
- Section for Transfusion Medicine, Capital Region Blood Bank, Rigshospitalet, University of Copenhagen , Copenhagen , Denmark
| | - Óttar Rolfsson
- Center for Systems Biology, University of Iceland, Reykjavik, Iceland; Department of Biochemistry and Molecular Biology, School of Health Sciences, University of Iceland, Reykjavik, Iceland
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6
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Sørensen KK, Simon‐Santamaria J, McCuskey RS, Smedsrød B. Liver Sinusoidal Endothelial Cells. Compr Physiol 2015; 5:1751-74. [DOI: 10.1002/cphy.c140078] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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7
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Abstract
Higher organisms rely on a closed cardiovascular circulatory system with blood vessels supplying vital nutrients and oxygen to distant tissues. Not surprisingly, vascular pathologies rank among the most life-threatening diseases. At the crux of most of these vascular pathologies are (dysfunctional) endothelial cells (ECs), the cells lining the blood vessel lumen. ECs display the remarkable capability to switch rapidly from a quiescent state to a highly migratory and proliferative state during vessel sprouting. This angiogenic switch has long been considered to be dictated by angiogenic growth factors (eg, vascular endothelial growth factor) and other signals (eg, Notch) alone, but recent findings show that it is also driven by a metabolic switch in ECs. Furthermore, these changes in metabolism may even override signals inducing vessel sprouting. Here, we review how EC metabolism differs between the normal and dysfunctional/diseased vasculature and how it relates to or affects the metabolism of other cell types contributing to the pathology. We focus on the biology of ECs in tumor blood vessel and diabetic ECs in atherosclerosis as examples of the role of endothelial metabolism in key pathological processes. Finally, current as well as unexplored EC metabolism-centric therapeutic avenues are discussed.
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Affiliation(s)
- Guy Eelen
- From the Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center, Department of Oncology, KU Leuven, Leuven, Belgium (G.E., P.d.Z., P.C.); Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center, VIB, Leuven, Belgium (G.E., P.d.Z., P.C.); Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, New Haven, CT (M.S.); and Department of Cell Biology, Yale University School of Medicine, New Haven, CT (M.S.)
| | - Pauline de Zeeuw
- From the Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center, Department of Oncology, KU Leuven, Leuven, Belgium (G.E., P.d.Z., P.C.); Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center, VIB, Leuven, Belgium (G.E., P.d.Z., P.C.); Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, New Haven, CT (M.S.); and Department of Cell Biology, Yale University School of Medicine, New Haven, CT (M.S.)
| | - Michael Simons
- From the Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center, Department of Oncology, KU Leuven, Leuven, Belgium (G.E., P.d.Z., P.C.); Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center, VIB, Leuven, Belgium (G.E., P.d.Z., P.C.); Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, New Haven, CT (M.S.); and Department of Cell Biology, Yale University School of Medicine, New Haven, CT (M.S.)
| | - Peter Carmeliet
- From the Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center, Department of Oncology, KU Leuven, Leuven, Belgium (G.E., P.d.Z., P.C.); Laboratory of Angiogenesis and Neurovascular Link, Vesalius Research Center, VIB, Leuven, Belgium (G.E., P.d.Z., P.C.); Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, New Haven, CT (M.S.); and Department of Cell Biology, Yale University School of Medicine, New Haven, CT (M.S.).
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8
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Verdegem D, Moens S, Stapor P, Carmeliet P. Endothelial cell metabolism: parallels and divergences with cancer cell metabolism. Cancer Metab 2014; 2:19. [PMID: 25250177 PMCID: PMC4171726 DOI: 10.1186/2049-3002-2-19] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 08/14/2014] [Indexed: 02/08/2023] Open
Abstract
The stromal vasculature in tumors is a vital conduit of nutrients and oxygen for cancer cells. To date, the vast majority of studies have focused on unraveling the genetic basis of vessel sprouting (also termed angiogenesis). In contrast to the widely studied changes in cancer cell metabolism, insight in the metabolic regulation of angiogenesis is only just emerging. These studies show that metabolic pathways in endothelial cells (ECs) importantly regulate angiogenesis in conjunction with genetic signals. In this review, we will highlight these emerging insights in EC metabolism and discuss them in perspective of cancer cell metabolism. While it is generally assumed that cancer cells have unique metabolic adaptations, not shared by healthy non-transformed cells, we will discuss parallels and highlight differences between endothelial and cancer cell metabolism and consider possible novel therapeutic opportunities arising from targeting both cancer and endothelial cells.
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Affiliation(s)
- Dries Verdegem
- Laboratory of Angiogenesis and Neurovascular link, Vesalius Research Center, Department of Oncology, University of Leuven, Leuven 3000, Belgium ; Laboratory of Angiogenesis and Neurovascular link, Vesalius Research Center, VIB, K.U.Leuven, Campus Gasthuisberg, Herestraat 49, box 912, Leuven 3000, Belgium
| | - Stijn Moens
- Laboratory of Angiogenesis and Neurovascular link, Vesalius Research Center, Department of Oncology, University of Leuven, Leuven 3000, Belgium ; Laboratory of Angiogenesis and Neurovascular link, Vesalius Research Center, VIB, K.U.Leuven, Campus Gasthuisberg, Herestraat 49, box 912, Leuven 3000, Belgium
| | - Peter Stapor
- Laboratory of Angiogenesis and Neurovascular link, Vesalius Research Center, Department of Oncology, University of Leuven, Leuven 3000, Belgium ; Laboratory of Angiogenesis and Neurovascular link, Vesalius Research Center, VIB, K.U.Leuven, Campus Gasthuisberg, Herestraat 49, box 912, Leuven 3000, Belgium
| | - Peter Carmeliet
- Laboratory of Angiogenesis and Neurovascular link, Vesalius Research Center, Department of Oncology, University of Leuven, Leuven 3000, Belgium ; Laboratory of Angiogenesis and Neurovascular link, Vesalius Research Center, VIB, K.U.Leuven, Campus Gasthuisberg, Herestraat 49, box 912, Leuven 3000, Belgium
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9
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Effect of fasting on the metabolic response of liver to experimental burn injury. PLoS One 2013; 8:e54825. [PMID: 23393558 PMCID: PMC3564862 DOI: 10.1371/journal.pone.0054825] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 12/17/2012] [Indexed: 12/31/2022] Open
Abstract
Liver metabolism is altered after systemic injuries such as burns and trauma. These changes have been elucidated in rat models of experimental burn injury where the liver was isolated and perfused ex vivo. Because these studies were performed in fasted animals to deplete glycogen stores, thus simplifying quantification of gluconeogenesis, these observations reflect the combined impact of fasting and injury on liver metabolism. Herein we asked whether the metabolic response to experimental burn injury is different in fed vs. fasted animals. Rats were subjected to a cutaneous burn covering 20% of the total body surface area, or to similar procedures without administering the burn, hence a sham-burn. Half of the animals in the burn and sham-burn groups were fasted starting on postburn day 3, and the others allowed to continue ad libitum. On postburn day 4, livers were isolated and perfused for 1 hour in physiological medium supplemented with 10% hematocrit red blood cells. The uptake/release rates of major carbon and nitrogen sources, oxygen, and carbon dioxide were measured during the perfusion and the data fed into a mass balance model to estimate intracellular fluxes. The data show that in fed animals, injury increased glucose output mainly from glycogen breakdown and minimally impacted amino acid metabolism. In fasted animals, injury did not increase glucose output but increased urea production and the uptake of several amino acids, namely glutamine, arginine, glycine, and methionine. Furthermore, sham-burn animals responded to fasting by triggering gluconeogenesis from lactate; however, in burned animals the preferred gluconeogenic substrate was amino acids. Taken together, these results suggest that the fed state prevents the burn-induced increase in hepatic amino acid utilization for gluconeogenesis. The role of glycogen stores and means to increase and/or maintain internal sources of glucose to prevent increased hepatic amino acid utilization warrant further studies.
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10
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Oxidative stress increases SNAT1 expression and stimulates cysteine uptake in freshly isolated rat cardiomyocytes. Amino Acids 2010; 40:517-26. [PMID: 20602128 DOI: 10.1007/s00726-010-0664-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Accepted: 06/15/2010] [Indexed: 12/13/2022]
Abstract
Intracellular cysteine availability is an important rate-limiting factor governing glutathione synthesis in the heart. This is also dependent on the magnitude and rate of cysteine uptake into cardiomyocytes, which has been little studied. This study investigated the hypothesis that changes to cysteine transporter expression and activity during oxidative stress influence cardiomyocyte glutathione levels. The uptake of 0-3 mM L-[(35)S]cysteine into ventricular cardiomyocytes isolated from adult male Wistar rats was measured using oil filtration. Cysteine transporter expression was investigated by conventional and real-time quantitative reverse-transcription polymerase chain reaction and Western blotting. Glutathione levels were measured enzymatically. Oxidative stress was induced via 0-6 h incubation with 0.05 mM H(2)O(2). Cysteine uptake was greatest in sodium-containing media and was inhibited by glutamine, 2-(methylamino)-isobutyric acid (αMeAIB), serine or alanine. The K(m) and V(max) of the αMeAIB insensitive and sensitive portions were 0.133 ± 0.01 mM and 468.11 ± 9.04 pmol/μl cell vol/min, and 0.557 ± 0.096 mM and 279.87 ± 16.06 pmol/μl cell vol/min, respectively. Cardiomyocytes expressed ASCT2, SNAT1 and SNAT2 but not ASCT1. Oxidative stress significantly enhanced cysteine uptake, which was attenuated by αMeAIB. This was accompanied by significantly enhanced SNAT1 expression, whilst SNAT2 and ASCT2 were unaffected. Incubation with cysteine significantly reduced the oxidative-stress-induced decline in cardiomyocyte glutathione as compared to cells incubated without cysteine or cells incubated with cysteine and αMeAIB. In conclusion, under control conditions SNAT transporters aid in the delivery of cysteine for cardiomyocyte GSH synthesis, whilst oxidative stress increases cardiomyocyte cysteine uptake and stimulates cardiomyocyte SNAT1 expression.
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11
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Comar JF, Suzuki-Kemmelmeier F, Nascimento EA, Bracht A. Flexibility of the hepatic zonation of carbon and nitrogen fluxes linked to lactate and pyruvate transformations in the presence of ammonia. Am J Physiol Gastrointest Liver Physiol 2007; 293:G838-49. [PMID: 17690175 DOI: 10.1152/ajpgi.00120.2007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
It has been proposed that key enzymes of ureagenesis and the alanine aminotransferase activity predominate in periportal hepatocytes. However, ureagenesis from alanine, when measured in the perfused liver, did not show periportal predominance and even the release of the direct products of alanine transformation, lactate and pyruvate, was higher in perivenous cells. An alternative way of analyzing the functional distributions of alanine aminotransferase and the urea cycle along the hepatic acini would be to measure alanine and urea production from precursors such as lactate or pyruvate plus ammonia. In the present work these aspects were investigated in the bivascularly perfused rat liver. The results of the present study confirm that gluconeogenesis and the associated oxygen uptake tend to predominate in the periportal region. Alanine synthesis from lactate and pyruvate plus ammonia, however, predominated in the perivenous region. Furthermore, no predominance of ureagenesis in the periportal region was found, except for conditions of high ammonia concentrations plus oxidizing conditions induced by pyruvate. These observations corroborate the view that data on enzyme activity or expression alone cannot be extrapolated unconditionally to the living cell. The current view of the hepatic ammonia-detoxifying system proposes that the small perivenous fraction of glutamine synthesizing perivenous cells removes a minor fraction of ammonia that escapes from ureagenesis in periportal cells. However, since urea synthesis occurs at high rates in all hepatocytes with the possible exclusion of those cells not possessing carbamoyl-phosphate synthase, it is probable that ureagenesis is equally important as an ammonia-detoxifying mechanism in the perivenous region.
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Affiliation(s)
- Jurandir Fernando Comar
- Laboratory of Liver Metabolism, Dept. of Biochemistry, Univ. of Maringá, 87020900 Maringá, Brazil
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12
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Nedredal GI, Elvevold K, Ytrebø LM, Fuskevåg OM, Pettersen I, Bertheussen K, Langbakk B, Smedsrød B, Revhaug A. Significant contribution of liver nonparenchymal cells to metabolism of ammonia and lactate and cocultivation augments the functions of a bioartificial liver. Am J Physiol Gastrointest Liver Physiol 2007; 293:G75-83. [PMID: 17363468 DOI: 10.1152/ajpgi.00245.2006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A bioartificial liver (BAL) will bridge patients with acute liver failure (ALF) to either spontaneous regeneration or liver transplantation. The nitrogen metabolism is important in ALF, and the metabolism of nonparenchymal liver cells (NPCs) is poorly understood. The scope of this study was to investigate whether cocultivation of hepatocytes with NPCs would augment the functions of a BAL (HN-BAL) compared with a BAL equipped with only hepatocytes (H-BAL). In addition, NPCs were similarly cultivated alone. The cells were cultivated for 8 days in simulated microgravity with serum-free growth medium. With NPCs, initial ammonia and lactate production were fivefold and over twofold higher compared with later time periods despite sufficient oxygen supply. Initial lactate production and glutamine consumption were threefold higher in HN-BAL than in H-BAL. With NPCs, initial glutamine consumption was two- to threefold higher compared with later time periods, whereas initial ornithine production and arginine consumption were over four- and eightfold higher compared with later time periods. In NPCs, the conversion of glutamine to glutamate and ammonia can be explained by the presence of glutaminase, as revealed by PCR analysis. Drug metabolism and clearance of aggregated gamma globulin, probes administered to test functions of hepatocytes and NPCs, respectively, were higher in HN-BAL than in H-BAL. In conclusion, NPCs produce ammonia by hydrolysis of amino acids and may contribute to the pathogenesis of ALF. High amounts of lactate are produced by NPCs under nonhypoxic conditions. Cocultivation augments differentiated functions such as drug metabolism and clearance of aggregated gamma-globulin.
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Affiliation(s)
- Geir I Nedredal
- Department of Digestive Surgery, University Hospital of Northern Norway, 9038 Tromsø, Norway.
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13
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Baglietto-Vargas D, LóPEZ-TéLLEZ J, MORENO-GONZáLEZ I, GUTIéRREZ* A, Aledo J. Segregation of two glutaminase isoforms in islets of Langerhans. Biochem J 2004; 381:483-7. [PMID: 15089745 PMCID: PMC1133855 DOI: 10.1042/bj20040523] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2004] [Accepted: 04/19/2004] [Indexed: 01/20/2023]
Abstract
Despite the importance of glutamatergic signalling in the co-ordination of hormone secretion, the identity of the enzyme for the production of glutamate in beta-cells is still unresolved. We have found that the endocrine pancreas co-expresses two isoforms of GA (glutaminase), denoted as kidney-type (KGA) and liver-type (LGA), with a complementary cellular pattern of expression. Whereas KGA was mainly present in alpha-cells, LGA was very abundant in beta-cells. This spatial segregation may have important functional implications, facilitating a differential regulation of glutamate production in insulin- and glucagon-secreting cells.
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Affiliation(s)
- David Baglietto-Vargas
- *Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
| | - Juan F. LóPEZ-TéLLEZ
- *Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
| | - Inés MORENO-GONZáLEZ
- *Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
| | - Antonia GUTIéRREZ*
- *Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
- Correspondence may be addressed to either of the authors (e-mail and )
| | - J. Carlos Aledo
- †Departamento de Biología Molecular y Bioquímica, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
- Correspondence may be addressed to either of the authors (e-mail and )
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14
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Pérez-Gómez C, Matés JM, Gómez-Fabre PM, del Castillo-Olivares A, Alonso FJ, Márquez J. Genomic organization and transcriptional analysis of the human l-glutaminase gene. Biochem J 2003; 370:771-84. [PMID: 12444921 PMCID: PMC1223212 DOI: 10.1042/bj20021445] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2002] [Revised: 10/25/2002] [Accepted: 11/25/2002] [Indexed: 11/17/2022]
Abstract
In mammals, glutaminase (GA) is expressed in most tissues, but the regulation of organ-specific expression is largely unknown. Therefore, as an essential step towards studying the regulation of GA expression, the human liver-type GA (hLGA) gene has been characterized. LGA genomic sequences were isolated using the genome walking technique. Analysis and comparison of these sequences with two LGA cDNA clones and the Human Genome Project database, allowed the determination of the genomic organization of the LGA gene. The gene has 18 exons and is approx. 18 kb long. All exon/intron junction sequences conform to the GT/AG rule. Progressive deletion analysis of LGA promoter-luciferase constructs indicated that the core promoter is located between nt -141 and +410, with several potential regulatory elements: CAAT, GC, TATA-like, Ras-responsive element binding protein and specificity protein 1 (Sp1) sites. The minimal promoter was mapped within +107 and +410, where only an Sp1 binding site is present. Mutation experiments suggested that two CAAT recognition elements near the transcription-initiation site (-138 and -87), play a crucial role for optimal promoter activity. Electrophoretic mobility-shift assays confirmed the importance of CAAT- and TATA-like boxes to enhance basal transcription, and demonstrated that HNF-1 motif is a significant distal element for transcriptional regulation of the hLGA gene.
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Affiliation(s)
- Cristina Pérez-Gómez
- Departamento de Biología Molecular y Bioquímica, Laboratorio de Química de Proteínas, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
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15
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Mann GE, Yudilevich DL, Sobrevia L. Regulation of amino acid and glucose transporters in endothelial and smooth muscle cells. Physiol Rev 2003; 83:183-252. [PMID: 12506130 DOI: 10.1152/physrev.00022.2002] [Citation(s) in RCA: 319] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
While transport processes for amino acids and glucose have long been known to be expressed in the luminal and abluminal membranes of the endothelium comprising the blood-brain and blood-retinal barriers, it is only within the last decades that endothelial and smooth muscle cells derived from peripheral vascular beds have been recognized to rapidly transport and metabolize these nutrients. This review focuses principally on the mechanisms regulating amino acid and glucose transporters in vascular endothelial cells, although we also summarize recent advances in the understanding of the mechanisms controlling membrane transport activity and expression in vascular smooth muscle cells. We compare the specificity, ionic dependence, and kinetic properties of amino acid and glucose transport systems identified in endothelial cells derived from cerebral, retinal, and peripheral vascular beds and review the regulation of transport by vasoactive agonists, nitric oxide (NO), substrate deprivation, hypoxia, hyperglycemia, diabetes, insulin, steroid hormones, and development. In view of the importance of NO as a modulator of vascular tone under basal conditions and in disease and chronic inflammation, we critically review the evidence that transport of L-arginine and glucose in endothelial and smooth muscle cells is modulated by bacterial endotoxin, proinflammatory cytokines, and atherogenic lipids. The recent colocalization of the cationic amino acid transporter CAT-1 (system y(+)), nitric oxide synthase (eNOS), and caveolin-1 in endothelial plasmalemmal caveolae provides a novel mechanism for the regulation of NO production by L-arginine delivery and circulating hormones such insulin and 17beta-estradiol.
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Affiliation(s)
- Giovanni E Mann
- Centre for Cardiovascular Biology and Medicine, Guy's, King's, and St. Thomas' School of Biomedical Sciences, King's College London, London, United Kingdom.
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16
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Avissar NE, Ryan CK, Ganapathy V, Sax HC. Na(+)-dependent neutral amino acid transporter ATB(0) is a rabbit epithelial cell brush-border protein. Am J Physiol Cell Physiol 2001; 281:C963-71. [PMID: 11502573 DOI: 10.1152/ajpcell.2001.281.3.c963] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
System B(0) activity accounts for the majority of intestinal and kidney luminal neutral amino acid absorption. An amino acid transport system, called ATB(0) (also known as ASCT2), with functional characteristics similar to those of system B(0), has been recently cloned. We generated polyclonal antibodies to human and rabbit ATB(0) COOH-terminal peptides and used Western blot analysis to detect ATB(0) protein in rabbit tissues, rabbit ileal brush-border membrane vesicles (BBMV), and HeLa cells transfected with plasmids containing ATB(0) cDNAs. Immunohistochemistry was used to localize ATB(0) in rabbit kidney and intestine. In Western blots of rabbit tissues, ATB(0) was a broad smear of 78- to 85-kDa proteins. In transfected HeLa cells, ATB(0) appeared as a smear consisting of 57- to 65-kDa proteins. The highest expression was found in the kidney. ATB(0) was enriched in rabbit ileal BBMV and in HeLa cells transfected with ATB(0) cDNAs. In the kidney and in the intestine, ATB(0) was confined to the brush-border membrane (BBM) of the proximal tubular cell and of the enterocyte, respectively. Tissue and intracellular distribution of ATB(0) protein parallels that of system B(0) activity. ATB(0) protein could be the transporter responsible for system B(0) in the BBM of epithelial cells.
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Affiliation(s)
- N E Avissar
- Department of Surgery, University of Rochester Medical Center, Rochester, New York 14642, USA.
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