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Köhler S, Winkler U, Junge T, Lippmann K, Eilers J, Hirrlinger J. Gray and white matter astrocytes differ in basal metabolism but respond similarly to neuronal activity. Glia 2023; 71:229-244. [PMID: 36063073 DOI: 10.1002/glia.24268] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 07/12/2022] [Accepted: 08/22/2022] [Indexed: 11/10/2022]
Abstract
Astrocytes are a heterogeneous population of glial cells in the brain, which adapt their properties to the requirements of the local environment. Two major groups of astrocytes are protoplasmic astrocytes residing in gray matter as well as fibrous astrocytes of white matter. Here, we compared the energy metabolism of astrocytes in the cortex and corpus callosum as representative gray matter and white matter regions, in acute brain slices taking advantage of genetically encoded fluorescent nanosensors for the NADH/NAD+ redox ratio and for ATP. Astrocytes of the corpus callosum presented a more reduced basal NADH/NAD+ redox ratio, and a lower cytosolic concentration of ATP compared to cortical astrocytes. In cortical astrocytes, the neurotransmitter glutamate and increased extracellular concentrations of K+ , typical correlates of neuronal activity, induced a more reduced NADH/NAD+ redox ratio. While application of glutamate decreased [ATP], K+ as well as the combination of glutamate and K+ resulted in an increase of ATP levels. Strikingly, a very similar regulation of metabolism by K+ and glutamate was observed in astrocytes in the corpus callosum. Finally, strong intrinsic neuronal activity provoked by application of bicuculline and withdrawal of Mg2+ caused a shift of the NADH/NAD+ redox ratio to a more reduced state as well as a slight reduction of [ATP] in gray and white matter astrocytes. In summary, the metabolism of astrocytes in cortex and corpus callosum shows distinct basal properties, but qualitatively similar responses to neuronal activity, probably reflecting the different environment and requirements of these brain regions.
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Affiliation(s)
- Susanne Köhler
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - Ulrike Winkler
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - Tabea Junge
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - Kristina Lippmann
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - Jens Eilers
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany
| | - Johannes Hirrlinger
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig, Germany.,Department of Neurogenetics, Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
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2
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Wang F, Guo L, Wu Z, Zhang T, Dong D, Wu B. The Clock gene regulates kainic acid-induced seizures through inhibiting ferroptosis in mice. J Pharm Pharmacol 2022; 74:1640-1650. [PMID: 35704277 DOI: 10.1093/jpp/rgac042] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 05/20/2022] [Indexed: 12/28/2022]
Abstract
OBJECTIVES Temporal lobe epilepsy (TLE) is a common and intractable form of epilepsy. There is a strong need to better understand molecular events underlying TLE and to find novel therapeutic agents. Here we aimed to investigate the role of Clock and ferroptosis in regulating TLE. METHODS TLE model was established by treating mice with kainic acid (KA). Regulatory effects of the Clock gene on KA-induced seizures and ferroptosis were evaluated using Clock knockout (Clock-/-) mice. mRNA and protein levels were determined by quantitative real-time PCR and western blotting, respectively. Ferroptosis was assessed by measuring the levels of iron, GSH and ROS. Transcriptional regulation was studied using a combination of luciferase reporter, mobility shift and chromatin immunoprecipitation (ChIP) assays. KEY FINDINGS We found that Clock ablation exacerbated KA-induced seizures in mice, accompanied by enhanced ferroptosis in the hippocampus. Clock ablation reduced the hippocampal expression of GPX4 and PPAR-γ, two ferroptosis-inhibitory factors, in mice and in N2a cells. Moreover, Clock regulates diurnal expression of GPX4 and PPAR-γ in mouse hippocampus and rhythmicity in KA-induced seizures. Consistent with this finding, Clock overexpression up-regulated GPX4 and PPAR-γ and protected against ferroptosis in N2a cells. In addition, luciferase reporter, mobility shift and ChIP assays showed that CLOCK trans-activated Gpx4 and Ppar-γ through direct binding to the E-box elements in the gene promoters. CONCLUSION CLOCK protects against KA-induced seizures through increased expression of GPX4 and PPAR-γ and inhibition of ferroptosis.
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Affiliation(s)
- Fei Wang
- College of Pharmacy, Jinan University, Guangzhou, China.,Institute of Molecular Rhythm and Metabolism, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Lianxia Guo
- College of Pharmacy, Jinan University, Guangzhou, China.,Institute of Molecular Rhythm and Metabolism, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Zhengping Wu
- School of Medicine, Yichun University, Yichun, China
| | - Tianpeng Zhang
- Institute of Molecular Rhythm and Metabolism, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Dong Dong
- School of Medicine, Jinan University, Guangzhou, China
| | - Baojian Wu
- Institute of Molecular Rhythm and Metabolism, Guangzhou University of Chinese Medicine, Guangzhou, China
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3
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Kong E, Li Y, Deng M, Hua T, Yang M, Li J, Feng X, Yuan H. Glycometabolism Reprogramming of Glial Cells in Central Nervous System: Novel Target for Neuropathic Pain. Front Immunol 2022; 13:861290. [PMID: 35669777 PMCID: PMC9163495 DOI: 10.3389/fimmu.2022.861290] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 04/26/2022] [Indexed: 11/13/2022] Open
Abstract
Neuropathic pain is characterized by hyperalgesia and allodynia. Inflammatory response is conducive to tissue recovery upon nerve injury, but persistent and exaggerated inflammation is detrimental and participates in neuropathic pain. Synaptic transmission in the nociceptive pathway, and particularly the balance between facilitation and inhibition, could be affected by inflammation, which in turn is regulated by glial cells. Importantly, glycometabolism exerts a vital role in the inflammatory process. Glycometabolism reprogramming of inflammatory cells in neuropathic pain is characterized by impaired oxidative phosphorylation in mitochondria and enhanced glycolysis. These changes induce phenotypic transition of inflammatory cells to promote neural inflammation and oxidative stress in peripheral and central nervous system. Accumulation of lactate in synaptic microenvironment also contributes to synaptic remodeling and central sensitization. Previous studies mainly focused on the glycometabolism reprogramming in peripheral inflammatory cells such as macrophage or lymphocyte, little attention was paid to the regulation effects of glycometabolism reprogramming on the inflammatory responses in glial cells. This review summarizes the evidences for glycometabolism reprogramming in peripheral inflammatory cells, and presents a small quantity of present studies on glycometabolism in glial cells, expecting to promote the exploration in glycometabolism in glial cells of neuropathic pain.
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Affiliation(s)
- Erliang Kong
- Department of Anesthesiology, Changzheng Hospital, Second Affiliated Hospital of Naval Medical University, Shanghai, China.,Department of Anesthesiology, The No. 988 Hospital of Joint Logistic Support Force of Chinese People's Liberation Army, Zhengzhou, China
| | - Yongchang Li
- Department of Anesthesiology, Changzheng Hospital, Second Affiliated Hospital of Naval Medical University, Shanghai, China
| | - Mengqiu Deng
- Department of Anesthesiology, Changzheng Hospital, Second Affiliated Hospital of Naval Medical University, Shanghai, China
| | - Tong Hua
- Department of Anesthesiology, Changzheng Hospital, Second Affiliated Hospital of Naval Medical University, Shanghai, China
| | - Mei Yang
- Department of Anesthesiology, Changzheng Hospital, Second Affiliated Hospital of Naval Medical University, Shanghai, China
| | - Jian Li
- Department of Anesthesiology, Changzheng Hospital, Second Affiliated Hospital of Naval Medical University, Shanghai, China
| | - Xudong Feng
- Department of Anesthesiology, The No. 988 Hospital of Joint Logistic Support Force of Chinese People's Liberation Army, Zhengzhou, China
| | - Hongbin Yuan
- Department of Anesthesiology, Changzheng Hospital, Second Affiliated Hospital of Naval Medical University, Shanghai, China
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4
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Schilling K, Zhai Y, Zhou Z, Zhou B, Brown E, Zhang X. High-resolution imaging of the osteogenic and angiogenic interface at the site of murine cranial bone defect repair via multiphoton microscopy. eLife 2022; 11:83146. [PMID: 36326085 PMCID: PMC9678361 DOI: 10.7554/elife.83146] [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: 08/31/2022] [Accepted: 10/31/2022] [Indexed: 11/05/2022] Open
Abstract
The spatiotemporal blood vessel formation and specification at the osteogenic and angiogenic interface of murine cranial bone defect repair were examined utilizing a high-resolution multiphoton-based imaging platform in conjunction with advanced optical techniques that allow interrogation of the oxygen microenvironment and cellular energy metabolism in living animals. Our study demonstrates the dynamic changes of vessel types, that is, arterial, venous, and capillary vessel networks at the superior and dura periosteum of cranial bone defect, suggesting a differential coupling of the vessel type with osteoblast expansion and bone tissue deposition/remodeling during repair. Employing transgenic reporter mouse models that label distinct types of vessels at the site of repair, we further show that oxygen distributions in capillary vessels at the healing site are heterogeneous as well as time- and location-dependent. The endothelial cells coupling to osteoblasts prefer glycolysis and are less sensitive to microenvironmental oxygen changes than osteoblasts. In comparison, osteoblasts utilize relatively more OxPhos and potentially consume more oxygen at the site of repair. Taken together, our study highlights the dynamics and functional significance of blood vessel types at the site of defect repair, opening up opportunities for further delineating the oxygen and metabolic microenvironment at the interface of bone tissue regeneration.
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Affiliation(s)
- Kevin Schilling
- Center for Musculoskeletal Research, University of Rochester, School of Medicine and DentistryRochesterUnited States,Department of Biomedical Engineering, University of RochesterRochesterUnited States
| | - Yuankn Zhai
- Center for Musculoskeletal Research, University of Rochester, School of Medicine and DentistryRochesterUnited States
| | - Zhuang Zhou
- Center for Musculoskeletal Research, University of Rochester, School of Medicine and DentistryRochesterUnited States
| | - Bin Zhou
- Shanghai Institutes for Biological SciencesShanghaiChina
| | - Edward Brown
- Department of Biomedical Engineering, University of RochesterRochesterUnited States
| | - Xinping Zhang
- Center for Musculoskeletal Research, University of Rochester, School of Medicine and DentistryRochesterUnited States
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5
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Malacrida L, Ranjit S, Jameson DM, Gratton E. The Phasor Plot: A Universal Circle to Advance Fluorescence Lifetime Analysis and Interpretation. Annu Rev Biophys 2021; 50:575-593. [PMID: 33957055 DOI: 10.1146/annurev-biophys-062920-063631] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The phasor approach to fluorescence lifetime imaging has become a common method to analyze complicated fluorescence signals from biological samples. The appeal of the phasor representation of complex fluorescence decays in biological systems is that a visual representation of the decay of entire cells or tissues can be used to easily interpret fundamental biological states related to metabolism and oxidative stress. Phenotyping based on autofluorescence provides new avenues for disease characterization and diagnostics. The phasor approach is a transformation of complex fluorescence decays that does not use fits to model decays and therefore has the same information content as the original data. The phasor plot is unique for a given system, is highly reproducible, and provides a robust method to evaluate the existence of molecular interactions such as Förster resonance energy transfer or the response of ion indicators. Recent advances permitquantification of multiple components from phasor plots in fluorescence lifetime imaging microscopy, which is not presently possible using data fitting methods, especially in biological systems.
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Affiliation(s)
- Leonel Malacrida
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California 92697, USA; .,Departamento de Fisiopatología, Hospital de Clínicas, Facultad de Medicina, Universidad de la República, 11600 Montevideo, Uruguay.,Advanced Bioimaging Unit, Institut Pasteur Montevideo and Universidad de la República-Uruguay, 11400 Montevideo, Uruguay
| | - Suman Ranjit
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California 92697, USA; .,Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC 20057, USA
| | - David M Jameson
- Department of Cell and Molecular Biology, University of Hawaii at Manoa, Honolulu, Hawaii 96813, USA
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California 92697, USA;
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6
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Schönfeld P, Reiser G. How the brain fights fatty acids' toxicity. Neurochem Int 2021; 148:105050. [PMID: 33945834 DOI: 10.1016/j.neuint.2021.105050] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 04/17/2021] [Accepted: 04/19/2021] [Indexed: 12/24/2022]
Abstract
Neurons spurn hydrogen-rich fatty acids for energizing oxidative ATP synthesis, contrary to other cells. This feature has been mainly attributed to a lower yield of ATP per reduced oxygen, as compared to glucose. Moreover, the use of fatty acids as hydrogen donor is accompanied by severe β-oxidation-associated ROS generation. Neurons are especially susceptible to detrimental activities of ROS due to their poor antioxidative equipment. It is also important to note that free fatty acids (FFA) initiate multiple harmful activities inside the cells, particularly on phosphorylating mitochondria. Several processes enhance FFA-linked lipotoxicity in the cerebral tissue. Thus, an uptake of FFA from the circulation into the brain tissue takes place during an imbalance between energy intake and energy expenditure in the body, a situation similar to that during metabolic syndrome and fat-rich diet. Traumatic or hypoxic brain injuries increase hydrolytic degradation of membrane phospholipids and, thereby elevate the level of FFA in neural cells. Accumulation of FFA in brain tissue is markedly associated with some inherited neurological disorders, such as Refsum disease or X-linked adrenoleukodystrophy (X-ALD). What are strategies protecting neurons against FFA-linked lipotoxicity? Firstly, spurning the β-oxidation pathway in mitochondria of neurons. Secondly, based on a tight metabolic communication between neurons and astrocytes, astrocytes donate metabolites to neurons for synthesis of antioxidants. Further, neuronal autophagy of ROS-emitting mitochondria combined with the transfer of degradation-committed FFA for their disposal in astrocytes, is a potent protective strategy against ROS and harmful activities of FFA. Finally, estrogens and neurosteroids are protective as triggers of ERK and PKB signaling pathways, consequently initiating the expression of various neuronal survival genes via the formation of cAMP response element-binding protein (CREB).
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Affiliation(s)
- Peter Schönfeld
- Institut für Biochemie und Zellbiologie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Leipziger Straße 44, D-39120, Magdeburg, Germany
| | - Georg Reiser
- Institut für Inflammation und Neurodegeneration (Neurobiochemie), Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Leipziger Straße 44, D-39120, Magdeburg, Germany.
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7
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Experimental competition induces immediate and lasting effects on the neurogenome in free-living female birds. Proc Natl Acad Sci U S A 2021; 118:2016154118. [PMID: 33753482 DOI: 10.1073/pnas.2016154118] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Periods of social instability can elicit adaptive phenotypic plasticity to promote success in future competition. However, the underlying molecular mechanisms have primarily been studied in captive and laboratory-reared animals, leaving uncertainty as to how natural competition among free-living animals affects gene activity. Here, we experimentally generated social competition among wild, cavity-nesting female birds (tree swallows, Tachycineta bicolor). After territorial settlement, we reduced the availability of key breeding resources (i.e., nest boxes), generating heightened competition; within 24 h we reversed the manipulation, causing aggressive interactions to subside. We sampled females during the peak of competition and 48 h after it ended, along with date-matched controls. We measured transcriptomic and epigenomic responses to competition in two socially relevant brain regions (hypothalamus and ventromedial telencephalon). Gene network analyses suggest that processes related to energy mobilization and aggression (e.g., dopamine synthesis) were up-regulated during competition, the latter of which persisted 2 d after competition had ended. Cellular maintenance processes were also down-regulated after competition. Competition additionally altered methylation patterns, particularly in pathways related to hormonal signaling, suggesting those genes were transcriptionally poised to respond to future competition. Thus, experimental competition among free-living animals shifts gene expression in ways that may facilitate the demands of competition at the expense of self-maintenance. Further, some of these effects persisted after competition ended, demonstrating the potential for epigenetic biological embedding of the social environment in ways that may prime individuals for success in future social instability.
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8
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Identification of PARP-1, Histone H1 and SIRT-1 as New Regulators of Breast Cancer-Related Aromatase Promoter I.3/II. Cells 2020; 9:cells9020427. [PMID: 32059481 PMCID: PMC7072628 DOI: 10.3390/cells9020427] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/06/2020] [Accepted: 02/10/2020] [Indexed: 12/19/2022] Open
Abstract
Paracrine interactions between malignant estrogen receptor positive (ER+) breast cancer cells and breast adipose fibroblasts (BAFs) stimulate estrogen biosynthesis by aromatase in BAFs. In breast cancer, mainly the cAMP-responsive promoter I.3/II-region mediates excessive aromatase expression. A rare single nucleotide variant (SNV) in this promoter region, which caused 70% reduction in promoter activity, was utilized for the identification of novel regulators of aromatase expression. To this end, normal and mutant promoter activities were measured in luciferase reporter gene assays. DNA-binding proteins were captured by DNA-affinity and identified by mass spectrometry. The DNA binding of proteins was analyzed using electrophoretic mobility shift assays, immunoprecipitation-based in vitro binding assays and by chromatin immunoprecipitation in BAFs in vivo. Protein expression and parylation were analyzed by western blotting. Aromatase activities and RNA-expression were measured in BAFs. Functional consequences of poly (ADP-ribose) polymerase-1 (PARP-1) knock-out, rescue or overexpression, respectively, were analyzed in murine embryonic fibroblasts (MEFs) and the 3T3-L1 cell model. In summary, PARP-1 and histone H1 (H1) were identified as critical regulators of aromatase expression. PARP-1-binding to the SNV-region was crucial for aromatase promoter activation. PARP-1 parylated H1 and competed with H1 for DNA-binding, thereby inhibiting its gene silencing action. In MEFs (PARP-1 knock-out and wild-type) and BAFs, PARP-1-mediated induction of the aromatase promoter showed bi-phasic dose responses in overexpression and inhibitor experiments, respectively. The HDAC-inhibitors butyrate, panobinostat and selisistat enhanced promoter I.3/II-mediated gene expression dependent on PARP-1-activity. Forskolin stimulation of BAFs increased promoter I.3/II-occupancy by PARP-1, whereas SIRT-1 competed with PARP-1 for DNA binding but independently activated the promoter I.3/II. Consistently, the inhibition of both PARP-1 and SIRT-1 increased the NAD+/NADH-ratio in BAFs. This suggests that cellular NAD+/NADH ratios control the complex interactions of PARP-1, H1 and SIRT-1 and regulate the interplay of parylation and acetylation/de-acetylation events with low NAD+/NADH ratios (reverse Warburg effect), promoting PARP-1 activation and estrogen synthesis in BAFs. Therefore, PARP-1 inhibitors could be useful in the treatment of estrogen-dependent breast cancers.
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9
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Ranjit S, Malacrida L, Stakic M, Gratton E. Determination of the metabolic index using the fluorescence lifetime of free and bound nicotinamide adenine dinucleotide using the phasor approach. JOURNAL OF BIOPHOTONICS 2019; 12:e201900156. [PMID: 31194290 PMCID: PMC6842045 DOI: 10.1002/jbio.201900156] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 06/09/2019] [Accepted: 06/12/2019] [Indexed: 05/05/2023]
Abstract
The fluorescence lifetime of nicotinamide adenine dinucleotide (NADH) is commonly used in conjunction with the phasor approach as a molecular biomarker to provide information on cellular metabolism of autofluorescence imaging of cells and tissue. However, in the phasor approach, the bound and free lifetime defining the phasor metabolic trajectory is a subject of debate. The fluorescence lifetime of NADH increases when bound to an enzyme, in contrast to the short multiexponential lifetime displayed by NADH in solution. The extent of fluorescence lifetime increase depends on the enzyme to which NADH is bound. With proper preparation of lactate dehydrogenase (LDH) using oxalic acid (OA) as an allosteric factor, bound NADH to LDH has a lifetime of 3.4 ns and is positioned on the universal semicircle of the phasor plot, inferring a monoexponential lifetime for this species. Surprisingly, measurements in the cellular environments with different metabolic states show a linear trajectory between free NADH at about 0.37 ns and bound NADH at 3.4 ns. These observations support that in a cellular environment, a 3.4 ns value could be used for bound NADH lifetime. The phasor analysis of many cell types shows a linear combination of fractional contributions of free and bound species NADH.
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Affiliation(s)
- Suman Ranjit
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California
| | - Leonel Malacrida
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California
- Departamento de Fisiopatología, Hospital de Clínicas, Universidad de la República, Montevideo, Uruguay
| | - Milka Stakic
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California
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10
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Dong Y, Sameni S, Digman MA, Brewer GJ. Reversibility of Age-related Oxidized Free NADH Redox States in Alzheimer's Disease Neurons by Imposed External Cys/CySS Redox Shifts. Sci Rep 2019; 9:11274. [PMID: 31375701 PMCID: PMC6677822 DOI: 10.1038/s41598-019-47582-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 07/10/2019] [Indexed: 12/21/2022] Open
Abstract
Redox systems including extracellular cysteine/cystine (Cys/CySS), intracellular glutathione/oxidized glutathione (GSH/GSSG) and nicotinamide adenine dinucleotide reduced/oxidized forms (NADH/NAD+) are critical for maintaining redox homeostasis. Aging as a major risk factor for Alzheimer’s disease (AD) is associated with oxidative shifts, decreases in anti-oxidant protection and dysfunction of mitochondria. Here, we examined the flexibility of mitochondrial-specific free NADH in live neurons from non-transgenic (NTg) or triple transgenic AD-like mice (3xTg-AD) of different ages under an imposed extracellular Cys/CySS oxidative or reductive condition. We used phasor fluorescence lifetime imaging microscopy (FLIM) to distinguish free and bound NADH in mitochondria, nuclei and cytoplasm. Under an external oxidative stress, a lower capacity for maintaining mitochondrial free NADH levels was found in old compared to young neurons and a further decline with genetic load. Remarkably, an imposed Cys/CySS reductive state rejuvenated the mitochondrial free NADH levels of old NTg neurons by 71% and old 3xTg-AD neurons by 89% to levels corresponding to the young neurons. Using FLIM as a non-invasive approach, we were able to measure the reversibility of aging subcellular free NADH levels in live neurons. Our results suggest a potential reductive treatment to reverse the loss of free NADH in old and Alzheimer’s neurons.
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Affiliation(s)
- Yue Dong
- Department of Biomedical Engineering, University of California Irvine, Irvine, California, United States of America
| | - Sara Sameni
- Department of Biomedical Engineering, University of California Irvine, Irvine, California, United States of America.,Laboratory of Fluorescence Dynamics, Department of Biomedical Engineering, University of California Irvine, Irvine, California, United States of America
| | - Michelle A Digman
- Department of Biomedical Engineering, University of California Irvine, Irvine, California, United States of America.,Laboratory of Fluorescence Dynamics, Department of Biomedical Engineering, University of California Irvine, Irvine, California, United States of America
| | - Gregory J Brewer
- Department of Biomedical Engineering, University of California Irvine, Irvine, California, United States of America. .,MIND Institute, Center for Neurobiology of Learning and Memory, University of California Irvine, Irvine, CA, United States of America.
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11
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Wang Q, Hu Y, Wan J, Dong B, Sun J. Lactate: A Novel Signaling Molecule in Synaptic Plasticity and Drug Addiction. Bioessays 2019; 41:e1900008. [PMID: 31270822 DOI: 10.1002/bies.201900008] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 05/20/2019] [Indexed: 12/21/2022]
Abstract
l-Lactate is emerging as a crucial regulatory nexus for energy metabolism in the brain and signaling transduction in synaptic plasticity, memory processes, and drug addiction instead of being merely a waste by-product of anaerobic glycolysis. In this review, the role of lactate in various memory processes, synapse plasticity and drug addiction on the basis of recent studies is summarized and discussed. To this end, three main parts are presented: first, lactate as an energy substrate in energy metabolism of the brain is described; second, lactate as a novel signaling molecule in synaptic plasticity, neural circuits, memory, and drug addiction is described; and third, in light of the above descriptions, it is plausible to speculate that lactate is predominantly a signaling molecule in specific memory processes and partly acts as an energy substrate. The future perspective in lactate signaling involving microglia and associated precise signaling pathways in the brain is highlighted.
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Affiliation(s)
- Qiuting Wang
- Key Laboratory for Experimental Teratology of the Ministry of Education, Department of Anatomy, School of Basic Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Ying Hu
- Department of Paediatrics, Jinan Zhangqiu District Hospital of TCM, Jinan, Shandong, 250200, China
| | - Jiale Wan
- Key Laboratory for Experimental Teratology of the Ministry of Education, Department of Anatomy, School of Basic Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Bo Dong
- Department of Cardiology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong, 250021, China.,Department of Vascular Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong, 250021, China
| | - Jinhao Sun
- Key Laboratory for Experimental Teratology of the Ministry of Education, Department of Anatomy, School of Basic Medicine, Shandong University, Jinan, Shandong, 250012, China
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12
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Dong Y, Digman MA, Brewer GJ. Age- and AD-related redox state of NADH in subcellular compartments by fluorescence lifetime imaging microscopy. GeroScience 2019; 41:51-67. [PMID: 30729413 DOI: 10.1007/s11357-019-00052-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 01/17/2019] [Indexed: 02/06/2023] Open
Abstract
Nicotinamide adenine dinucleotide (reduced form: NADH) serves as a vital redox-energy currency for reduction-oxidation homeostasis and fulfilling energetic demands. While NADH exists as free and bound forms, only free NADH is utilized for complex I to power oxidative phosphorylation, especially important in neurons. Here, we studied how much free NADH remains available for energy production in mitochondria of old living neurons. We hypothesize that free NADH in neurons from old mice is lower than the levels in young mice and even lower in neurons from the 3xTg-AD Alzheimer's disease (AD) mouse model. To assess free NADH, we used lifetime imaging of NADH autofluorescence with 2-photon excitation to be able to resolve the pool of NADH in mitochondria, cytoplasm, and nuclei. Primary neurons from old mice were characterized by a lower free/bound NADH ratio than young neurons from both non-transgenic (NTg) and more so in 3xTg-AD mice. Mitochondrial compartments maintained 26 to 41% more reducing NADH redox state than cytoplasm for each age, genotype, and sex. Aging diminished the mitochondrial free NADH concentration in NTg neurons by 43% and in 3xTg-AD by 50%. The lower free NADH with age suggests a decline in capacity to regenerate free NADH for energetic supply to power oxidative phosphorylation which further worsens in AD. Applying this non-invasive approach, we showed the most explicit measures yet of bioenergetic deficits in free NADH with aging at the subcellular level in live neurons from in-bred mice and an AD model.
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Affiliation(s)
- Yue Dong
- Department of Biomedical Engineering, University of California Irvine, Irvine, CA, USA
| | - Michelle A Digman
- Department of Biomedical Engineering, University of California Irvine, Irvine, CA, USA.,Laboratory of Fluorescence Dynamics, Department of Biomedical Engineering, University of California Irvine, Irvine, CA, USA
| | - Gregory J Brewer
- Department of Biomedical Engineering, University of California Irvine, Irvine, CA, USA. .,MIND Institute, Center for Neurobiology of Learning and Memory, University of California, Irvine, CA, USA.
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Dienel GA, Carlson GM. Major Advances in Brain Glycogen Research: Understanding of the Roles of Glycogen Have Evolved from Emergency Fuel Reserve to Dynamic, Regulated Participant in Diverse Brain Functions. ADVANCES IN NEUROBIOLOGY 2019; 23:1-16. [DOI: 10.1007/978-3-030-27480-1_1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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14
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Köhler S, Winkler U, Sicker M, Hirrlinger J. NBCe1 mediates the regulation of the NADH/NAD + redox state in cortical astrocytes by neuronal signals. Glia 2018; 66:2233-2245. [PMID: 30208253 DOI: 10.1002/glia.23504] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 06/19/2018] [Accepted: 06/25/2018] [Indexed: 12/20/2022]
Abstract
Astrocytes are a glial cell type, which is indispensable for brain energy metabolism. Within cells, the NADH/NAD+ redox state is a crucial node in metabolism connecting catabolic pathways to oxidative phosphorylation and ATP production in mitochondria. To characterize the dynamics of the intracellular NADH/NAD+ redox state in cortical astrocytes Peredox, a genetically encoded sensor for the NADH/NAD+ redox state, was expressed in cultured cortical astrocytes as well as in cortical astrocytes in acutely isolated brain slices. Calibration of the sensor in cultured astrocytes revealed a mean basal cytosolic NADH/NAD+ redox ratio of about 0.01; however, with a broad distribution and heterogeneity in the cell population, which was mirrored by a heterogeneous basal cellular concentration of lactate. Inhibition of glucose uptake decreased the NADH/NAD+ redox state while inhibition of lactate dehydrogenase or of lactate release resulted in an increase in the NADH/NAD+ redox ratio. Furthermore, the NADH/NAD+ redox state was regulated by the extracellular concentration of K+ , and application of the neurotransmitters ATP or glutamate increased the NADH/NAD+ redox state dependent on purinergic receptors and glutamate uptake, respectively. This regulation by K+ , ATP, and glutamate involved NBCe1 mediated sodium-bicarbonate transport. These results demonstrate that the NADH/NAD+ redox state in astrocytes is a metabolic node regulated by neuronal signals reflecting physiological activity, most likely contributing to adjust astrocytic metabolism to energy demand of the brain.
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Affiliation(s)
- Susanne Köhler
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
| | - Ulrike Winkler
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
| | - Marit Sicker
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
| | - Johannes Hirrlinger
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany.,Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
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15
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Bilan DS, Belousov VV. New tools for redox biology: From imaging to manipulation. Free Radic Biol Med 2017; 109:167-188. [PMID: 27939954 DOI: 10.1016/j.freeradbiomed.2016.12.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 12/02/2016] [Accepted: 12/03/2016] [Indexed: 12/12/2022]
Abstract
Redox reactions play a key role in maintaining essential biological processes. Deviations in redox pathways result in the development of various pathologies at cellular and organismal levels. Until recently, studies on transformations in the intracellular redox state have been significantly hampered in living systems. The genetically encoded indicators, based on fluorescent proteins, have provided new opportunities in biomedical research. The existing indicators already enable monitoring of cellular redox parameters in different processes including embryogenesis, aging, inflammation, tissue regeneration, and pathogenesis of various diseases. In this review, we summarize information about all genetically encoded redox indicators developed to date. We provide the description of each indicator and discuss its advantages and limitations, as well as points that need to be considered when choosing an indicator for a particular experiment. One chapter is devoted to the important discoveries that have been made by using genetically encoded redox indicators.
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Affiliation(s)
- Dmitry S Bilan
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, Russia
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16
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Yaseen MA, Sutin J, Wu W, Fu B, Uhlirova H, Devor A, Boas DA, Sakadžić S. Fluorescence lifetime microscopy of NADH distinguishes alterations in cerebral metabolism in vivo. BIOMEDICAL OPTICS EXPRESS 2017; 8:2368-2385. [PMID: 28663879 PMCID: PMC5480486 DOI: 10.1364/boe.8.002368] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 03/09/2017] [Accepted: 03/10/2017] [Indexed: 05/06/2023]
Abstract
Evaluating cerebral energy metabolism at microscopic resolution is important for comprehensively understanding healthy brain function and its pathological alterations. Here, we resolve specific alterations in cerebral metabolism in vivo in Sprague Dawley rats utilizing minimally-invasive 2-photon fluorescence lifetime imaging (2P-FLIM) measurements of reduced nicotinamide adenine dinucleotide (NADH) fluorescence. Time-resolved fluorescence lifetime measurements enable distinction of different components contributing to NADH autofluorescence. Ostensibly, these components indicate different enzyme-bound formulations of NADH. We observed distinct variations in the relative proportions of these components before and after pharmacological-induced impairments to several reactions involved in glycolytic and oxidative metabolism. Classification models were developed with the experimental data and used to predict the metabolic impairments induced during separate experiments involving bicuculline-induced seizures. The models consistently predicted that prolonged focal seizure activity results in impaired activity in the electron transport chain, likely the consequence of inadequate oxygen supply. 2P-FLIM observations of cerebral NADH will help advance our understanding of cerebral energetics at a microscopic scale. Such knowledge will aid in our evaluation of healthy and diseased cerebral physiology and guide diagnostic and therapeutic strategies that target cerebral energetics.
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Affiliation(s)
- Mohammad A. Yaseen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Jason Sutin
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Weicheng Wu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Buyin Fu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Hana Uhlirova
- Department of Neurosciences and Radiology, UC San Diego, La Jolla, CA, USA
- Current affiliation: Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic
| | - Anna Devor
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
- Department of Neurosciences and Radiology, UC San Diego, La Jolla, CA, USA
| | - David A. Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
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17
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Oheim M, Schmidt E, Hirrlinger J. Local energy on demand: Are 'spontaneous' astrocytic Ca 2+-microdomains the regulatory unit for astrocyte-neuron metabolic cooperation? Brain Res Bull 2017; 136:54-64. [PMID: 28450076 DOI: 10.1016/j.brainresbull.2017.04.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 03/18/2017] [Accepted: 04/21/2017] [Indexed: 12/21/2022]
Abstract
Astrocytes are a neural cell type critically involved in maintaining brain energy homeostasis as well as signaling. Like neurons, astrocytes are a heterogeneous cell population. Cortical astrocytes show a complex morphology with a highly branched aborization and numerous fine processes ensheathing the synapses of neighboring neurons, and typically extend one process connecting to blood vessels. Recent studies employing genetically encoded fluorescent calcium (Ca2+) indicators have described 'spontaneous' localized Ca2+-transients in the astrocyte periphery that occur asynchronously, independently of signals in other parts of the cells, and that do not involve somatic Ca2+ transients; however, neither it is known whether these Ca2+-microdomains occur at or near neuronal synapses nor have their molecular basis nor downstream effector(s) been identified. In addition to Ca2+ microdomains, sodium (Na+) transients occur in astrocyte subdomains, too, most likely as a consequence of Na+ co-transport with the neurotransmitter glutamate, which also regulates mitochondrial movements locally - as do cytoplasmic Ca2+ levels. In this review, we cover various aspects of these local signaling events and discuss how structural and biophysical properties of astrocytes might foster such compartmentation. Astrocytes metabolically interact with neurons by providing energy substrates to active neurons. As a single astrocyte branch covers hundreds to thousands of synapses, it is tempting to speculate that these metabolic interactions could occur localized to specific subdomains of astrocytes, perhaps even at the level of small groups of synapses. We discuss how astrocytic metabolism might be regulated at this scale and which signals might contribute to its regulation. We speculate that the astrocytic structures that light up transiently as Ca2+-microdomains might be the functional units of astrocytes linking signaling and metabolic processes to adapt astrocytic function to local energy demands. The understanding of these local regulatory and metabolic interactions will be fundamental to fully appreciate the complexity of brain energy homeostasis as well as its failure in disease and may shed new light on the controversy about neuron-glia bi-directional signaling at the tripartite synapse.
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Affiliation(s)
- Martin Oheim
- CNRS UMR 8118, Brain Physiology Laboratory, F-75006 Paris, France; Fédération de Recherche en Neurosciences FR3636, Faculté de Sciences Fondamentales et Biomédicales, Université Paris Descartes, PRES Université Sorbonne Paris Cité (USPC), F-75006 Paris, France.
| | - Elke Schmidt
- CNRS UMR 8118, Brain Physiology Laboratory, F-75006 Paris, France; Fédération de Recherche en Neurosciences FR3636, Faculté de Sciences Fondamentales et Biomédicales, Université Paris Descartes, PRES Université Sorbonne Paris Cité (USPC), F-75006 Paris, France
| | - Johannes Hirrlinger
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University of Leipzig, D-04103 Leipzig, Germany; Dept. of Neurogenetics, Max-Planck-Institute for Experimental Medicine, D-37075 Göttingen, Germany.
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18
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Hohnholt MC, Blumrich EM, Waagepetersen HS, Dringen R. The antidiabetic drug metformin decreases mitochondrial respiration and tricarboxylic acid cycle activity in cultured primary rat astrocytes. J Neurosci Res 2017; 95:2307-2320. [PMID: 28316081 DOI: 10.1002/jnr.24050] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 02/20/2017] [Accepted: 02/21/2017] [Indexed: 12/18/2022]
Abstract
Metformin is an antidiabetic drug that is used daily by millions of patients worldwide. Metformin is able to cross the blood-brain barrier and has recently been shown to increase glucose consumption and lactate release in cultured astrocytes. However, potential effects of metformin on mitochondrial tricarboxylic acid (TCA) cycle metabolism in astrocytes are unknown. We investigated this by mapping 13 C labeling in TCA cycle intermediates and corresponding amino acids after incubation of primary rat astrocytes with [U-13 C]glucose. The presence of metformin did not compromise the viability of cultured astrocytes during 4 hr of incubation, but almost doubled cellular glucose consumption and lactate release. Compared with control cells, the presence of metformin dramatically lowered the molecular 13 C carbon labeling (MCL) of the cellular TCA cycle intermediates citrate, α-ketoglutarate, succinate, fumarate, and malate, as well as the MCL of the TCA cycle intermediate-derived amino acids glutamate, glutamine, and aspartate. In addition to the total molecular 13 C labeling, analysis of the individual isotopomers of TCA cycle intermediates confirmed a severe decline in labeling and a significant lowering in TCA cycling ratio in metformin-treated astrocytes. Finally, the oxygen consumption of mitochondria isolated from metformin-treated astrocytes was drastically reduced in the presence of complex I substrates, but not of complex II substrates. These data demonstrate that exposure to metformin strongly impairs complex I-mediated mitochondrial respiration in astrocytes, which is likely to cause the observed decrease in labeling of mitochondrial TCA cycle intermediates and the stimulation of glycolytic lactate production. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Michaela C Hohnholt
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Eva-Maria Blumrich
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, Bremen, Germany.,Centre for Environmental Research and Sustainable Technology, Bremen, Germany
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, Bremen, Germany.,Centre for Environmental Research and Sustainable Technology, Bremen, Germany
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19
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Hohnholt MC, Blumrich EM, Waagepetersen HS, Dringen R. The tricarboxylic acid cycle activity in cultured primary astrocytes is strongly accelerated by the protein tyrosine kinase inhibitor tyrphostin 23. Neurochem Int 2016; 102:13-21. [PMID: 27894844 DOI: 10.1016/j.neuint.2016.11.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Revised: 11/09/2016] [Accepted: 11/14/2016] [Indexed: 11/28/2022]
Abstract
Tyrphostin 23 (T23) is a well-known inhibitor of protein tyrosine kinases and has been considered as potential anti-cancer drug. T23 was recently reported to acutely stimulate the glycolytic flux in primary cultured astrocytes. To investigate whether T23 also affects the tricarboxylic acid (TCA) cycle, we incubated primary rat astrocyte cultures with [U-13C]glucose in the absence or the presence of 100 μM T23 for 2 h and analyzed the 13C metabolite pattern. These incubation conditions did not compromise cell viability and confirmed that the presence of T23 doubled glycolytic lactate production. In addition, T23-treatment strongly increased the molecular carbon labeling of the TCA cycle intermediates citrate, succinate, fumarate and malate, and significantly increased the incorporation of 13C-labelling into the amino acids glutamate, glutamine and aspartate. These results clearly demonstrate that, in addition to glycolysis, also the mitochondrial TCA cycle is strongly accelerated after exposure of astrocytes to T23, suggesting that a protein tyrosine kinase may be involved in the regulation of the TCA cycle in astrocytes.
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Affiliation(s)
- Michaela C Hohnholt
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark.
| | - Eva-Maria Blumrich
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, PO. Box 330440, D-28334 Bremen, Germany; Centre for Environmental Research and Sustainable Technology, Leobener Strasse, D-28359 Bremen, Germany
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, PO. Box 330440, D-28334 Bremen, Germany; Centre for Environmental Research and Sustainable Technology, Leobener Strasse, D-28359 Bremen, Germany
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20
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Dienel GA, Rothman DL, Nordström CH. Microdialysate concentration changes do not provide sufficient information to evaluate metabolic effects of lactate supplementation in brain-injured patients. J Cereb Blood Flow Metab 2016; 36:1844-1864. [PMID: 27604313 PMCID: PMC5094313 DOI: 10.1177/0271678x16666552] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 08/03/2016] [Indexed: 12/31/2022]
Abstract
Cerebral microdialysis is a widely used clinical tool for monitoring extracellular concentrations of selected metabolites after brain injury and to guide neurocritical care. Extracellular glucose levels and lactate/pyruvate ratios have high diagnostic value because they can detect hypoglycemia and deficits in oxidative metabolism, respectively. In addition, patterns of metabolite concentrations can distinguish between ischemia and mitochondrial dysfunction, and are helpful to choose and evaluate therapy. Increased intracranial pressure can be life-threatening after brain injury, and hypertonic solutions are commonly used for pressure reduction. Recent reports have advocated use of hypertonic sodium lactate, based on claims that it is glucose sparing and provides an oxidative fuel for injured brain. However, changes in extracellular concentrations in microdialysate are not evidence that a rise in extracellular glucose level is beneficial or that lactate is metabolized and improves neuroenergetics. The increase in glucose concentration may reflect inhibition of glycolysis, glycogenolysis, and pentose phosphate shunt pathway fluxes by lactate flooding in patients with mitochondrial dysfunction. In such cases, lactate will not be metabolizable and lactate flooding may be harmful. More rigorous approaches are required to evaluate metabolic and physiological effects of administration of hypertonic sodium lactate to brain-injured patients.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR, USA, and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, USA
| | - Douglas L Rothman
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, USA
| | - Carl-Henrik Nordström
- Department of Neurosurgery, Lund University Hospital, Lund, Sweden, and Department of Neurosurgery, Odense University Hospital, Odense, Denmark
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21
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Bilan DS, Belousov VV. Genetically encoded probes for NAD +/NADH monitoring. Free Radic Biol Med 2016; 100:32-42. [PMID: 27387770 DOI: 10.1016/j.freeradbiomed.2016.06.018] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 06/04/2016] [Accepted: 06/18/2016] [Indexed: 12/18/2022]
Abstract
NAD+ and NADH participate in many metabolic reactions. The NAD+/NADH ratio is an important parameter reflecting the general metabolic and redox state of different types of cells. For a long time, in situ and in vivo NAD+/NADH monitoring has been hampered by the lack of suitable tools. The recent development of genetically encoded indicators based on fluorescent proteins linked to specific nucleotide-binding domains has already helped to address this monitoring problem. In this review, we will focus on four available indicators: Peredox, Frex family probes, RexYFP and SoNar. Each indicator has advantages and limitations. We will also discuss the most important points that should be considered when selecting a suitable indicator for certain experimental conditions.
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Affiliation(s)
- Dmitry S Bilan
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, Russia
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22
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Rae C, Sonnewald U. Astrocytes, Metabolism, Signaling and Brain Drains: Introduction to the Special Issue in Honor of Gerald Dienel. Neurochem Res 2016; 40:2383-5. [PMID: 26613618 DOI: 10.1007/s11064-015-1781-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Caroline Rae
- Neuroscience Research Australian & The University of New South Wales, Randwick, NSW, Australia.
| | - Ursula Sonnewald
- Norwegian University of Science and Technology (NTNU), Trondheim, Norway
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The Protein Tyrosine Kinase Inhibitor Tyrphostin 23 Strongly Accelerates Glycolytic Lactate Production in Cultured Primary Astrocytes. Neurochem Res 2016; 41:2607-2618. [PMID: 27278759 DOI: 10.1007/s11064-016-1972-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 05/29/2016] [Accepted: 06/01/2016] [Indexed: 02/07/2023]
Abstract
Tyrphostin 23 (T23) is a well-known inhibitor of protein tyrosine kinases. To investigate potential acute effects of T23 on the viability and the glucose metabolism of brain cells, we exposed cultured primary rat astrocytes to T23 for up to 4 h. While the viability and the morphology of the cultured astrocytes were not acutely affected by the presence of T23 in concentrations of up to 300 µM, this compound caused a rapid, time- and concentration-dependent increase in glucose consumption and lactate release. Maximal effects on glycolytic flux were found for incubations with 100 µM T23 for 2 h which doubled both glucose consumption and lactate production. The stimulation of glycolytic flux by T23 was reversible, completely abolished upon removal of the compound and not found in presence of other known inhibitors of endocytosis. Structurally related compounds such as tyrphostin 25 and catechol or modulators of AMP kinase activity did neither affect the basal nor the T23-stimulated lactate production by astrocytes. In contrast, the presence of the phosphatase inhibitor vanadate completely abolished the stimulation by T23 of astrocytic lactate production in a concentration-dependent manner. These data suggest that T23-sensitive phosphorylation/dephosphorylation events are involved in the regulation of astrocytic glycolysis.
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24
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Butterfield DA. Redox signaling in neurodegeneration. Neurobiol Dis 2015; 84:1-3. [PMID: 26171987 DOI: 10.1016/j.nbd.2015.07.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 07/06/2015] [Indexed: 12/20/2022] Open
Affiliation(s)
- D Allan Butterfield
- Department of Chemistry and Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40506-0055, USA.
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