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Franco F, Bevilacqua A, Wu RM, Kao KC, Lin CP, Rousseau L, Peng FT, Chuang YM, Peng JJ, Park J, Xu Y, Cassotta A, Yu YR, Speiser DE, Sallusto F, Ho PC. Regulatory circuits of mitophagy restrict distinct modes of cell death during memory CD8 + T cell formation. Sci Immunol 2023; 8:eadf7579. [PMID: 37738363 DOI: 10.1126/sciimmunol.adf7579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 08/11/2023] [Indexed: 09/24/2023]
Abstract
Mitophagy, a central process guarding mitochondrial quality, is commonly impaired in human diseases such as Parkinson's disease, but its impact in adaptive immunity remains unclear. The differentiation and survival of memory CD8+ T cells rely on oxidative metabolism, a process that requires robust mitochondrial quality control. Here, we found that Parkinson's disease patients have a reduced frequency of CD8+ memory T cells compared with healthy donors and failed to form memory T cells upon vaccination against COVID-19, highlighting the importance of mitochondrial quality control for memory CD8+ T cell formation. We further uncovered that regulators of mitophagy, including Parkin and NIX, were up-regulated in response to interleukin-15 (IL-15) for supporting memory T cell formation. Mechanistically, Parkin suppressed VDAC1-dependent apoptosis in memory T cells. In contrast, NIX expression in T cells counteracted ferroptosis by preventing metabolic dysfunction resulting from impaired mitophagy. Together, our results indicate that the mitophagy machinery orchestrates survival and metabolic dynamics required for memory T cell formation, as well as highlight a deficit in T cell-mediated antiviral responses in Parkinson's disease patients.
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Affiliation(s)
- Fabien Franco
- Department of Fundamental Oncology, University of Lausanne, Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch, Epalinges, Switzerland
| | - Alessio Bevilacqua
- Department of Fundamental Oncology, University of Lausanne, Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch, Epalinges, Switzerland
| | - Ruey-Mei Wu
- Neurology Department, National Taiwan University Hospital, Taipei, Taiwan
| | - Kung-Chi Kao
- Department of Fundamental Oncology, University of Lausanne, Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch, Epalinges, Switzerland
| | - Chun-Pu Lin
- Department of Fundamental Oncology, University of Lausanne, Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch, Epalinges, Switzerland
| | - Lorène Rousseau
- Department of Fundamental Oncology, University of Lausanne, Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch, Epalinges, Switzerland
| | - Fu-Ti Peng
- Neurology Department, National Taiwan University Hospital, Taipei, Taiwan
| | - Yu-Ming Chuang
- Department of Fundamental Oncology, University of Lausanne, Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch, Epalinges, Switzerland
| | - Jhan-Jie Peng
- Department of Fundamental Oncology, University of Lausanne, Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch, Epalinges, Switzerland
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan City, Taiwan
| | - Jaeoh Park
- Department of Fundamental Oncology, University of Lausanne, Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch, Epalinges, Switzerland
| | - Yingxi Xu
- Department of Fundamental Oncology, University of Lausanne, Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch, Epalinges, Switzerland
| | - Antonino Cassotta
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Yi-Ru Yu
- Department of Fundamental Oncology, University of Lausanne, Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch, Epalinges, Switzerland
| | - Daniel E Speiser
- Department of Fundamental Oncology, University of Lausanne, Epalinges, Switzerland
| | - Federica Sallusto
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
- Institute of Microbiology, ETH Zürich, Zürich, Switzerland
| | - Ping-Chih Ho
- Department of Fundamental Oncology, University of Lausanne, Epalinges, Switzerland
- Ludwig Institute for Cancer Research, Lausanne Branch, Epalinges, Switzerland
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2
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Enhanced Ca 2+ Entry Sustains the Activation of Akt in Glucose Deprived SH-SY5Y Cells. Int J Mol Sci 2022; 23:ijms23031386. [PMID: 35163310 PMCID: PMC8835965 DOI: 10.3390/ijms23031386] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/23/2022] [Accepted: 01/24/2022] [Indexed: 12/27/2022] Open
Abstract
The two crucial cellular insults that take place during cerebral ischemia are the loss of oxygen and loss of glucose, which can both activate a cascade of events leading to neuronal death. In addition, the toxic overactivation of neuronal excitatory receptors, leading to Ca2+ overload, may contribute to ischemic neuronal injury. Brain ischemia can be simulated in vitro by oxygen/glucose deprivation, which can be reversible by the re-establishment of physiological conditions. Accordingly, we examined the effects of glucose deprivation on the PI3K/Akt survival signaling pathway and its crosstalk with HIF-1α and Ca2+ homeostasis in SH-SY5Y human neuroblastoma cells. It was found that glucose withdrawal decreased HIF-1α protein levels even in the presence of the ischemia-mimicking CoCl2. On the contrary, and despite neuronal death, we identified a strong activation of the master pro-survival kinase Akt, a finding that was also confirmed by the increased phosphorylation of GSK3, a direct target of p-Akt. Remarkably, the elevated Ca2+ influx recorded was found to promptly trigger the activation of Akt, while a re-addition of glucose resulted in rapid restoration of both Ca2+ entry and p-Akt levels, highlighting the plasticity of neurons to respond to ischemic challenges and the important role of glucose homeostasis for multiple neurological disorders.
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Myrka A, Buck L. Cytoskeletal Arrest: An Anoxia Tolerance Mechanism. Metabolites 2021; 11:metabo11080561. [PMID: 34436502 PMCID: PMC8401981 DOI: 10.3390/metabo11080561] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/13/2021] [Accepted: 08/14/2021] [Indexed: 12/16/2022] Open
Abstract
Polymerization of actin filaments and microtubules constitutes a ubiquitous demand for cellular adenosine-5′-triphosphate (ATP) and guanosine-5′-triphosphate (GTP). In anoxia-tolerant animals, ATP consumption is minimized during overwintering conditions, but little is known about the role of cell structure in anoxia tolerance. Studies of overwintering mammals have revealed that microtubule stability in neurites is reduced at low temperature, resulting in withdrawal of neurites and reduced abundance of excitatory synapses. Literature for turtles is consistent with a similar downregulation of peripheral cytoskeletal activity in brain and liver during anoxic overwintering. Downregulation of actin dynamics, as well as modification to microtubule organization, may play vital roles in facilitating anoxia tolerance. Mitochondrial calcium release occurs during anoxia in turtle neurons, and subsequent activation of calcium-binding proteins likely regulates cytoskeletal stability. Production of reactive oxygen species (ROS) formation can lead to catastrophic cytoskeletal damage during overwintering and ROS production can be regulated by the dynamics of mitochondrial interconnectivity. Therefore, suppression of ROS formation is likely an important aspect of cytoskeletal arrest. Furthermore, gasotransmitters can regulate ROS levels, as well as cytoskeletal contractility and rearrangement. In this review we will explore the energetic costs of cytoskeletal activity, the cellular mechanisms regulating it, and the potential for cytoskeletal arrest being an important mechanism permitting long-term anoxia survival in anoxia-tolerant species, such as the western painted turtle and goldfish.
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Affiliation(s)
- Alexander Myrka
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada;
| | - Leslie Buck
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada;
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
- Correspondence: ; Tel.: +1-416-978-3506
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Yu YR, Imrichova H, Wang H, Chao T, Xiao Z, Gao M, Rincon-Restrepo M, Franco F, Genolet R, Cheng WC, Jandus C, Coukos G, Jiang YF, Locasale JW, Zippelius A, Liu PS, Tang L, Bock C, Vannini N, Ho PC. Disturbed mitochondrial dynamics in CD8 + TILs reinforce T cell exhaustion. Nat Immunol 2020; 21:1540-1551. [PMID: 33020660 DOI: 10.1038/s41590-020-0793-3] [Citation(s) in RCA: 241] [Impact Index Per Article: 60.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 08/24/2020] [Indexed: 12/19/2022]
Abstract
The metabolic challenges present in tumors attenuate the metabolic fitness and antitumor activity of tumor-infiltrating T lymphocytes (TILs). However, it remains unclear whether persistent metabolic insufficiency can imprint permanent T cell dysfunction. We found that TILs accumulated depolarized mitochondria as a result of decreased mitophagy activity and displayed functional, transcriptomic and epigenetic characteristics of terminally exhausted T cells. Mechanistically, reduced mitochondrial fitness in TILs was induced by the coordination of T cell receptor stimulation, microenvironmental stressors and PD-1 signaling. Enforced accumulation of depolarized mitochondria with pharmacological inhibitors induced epigenetic reprogramming toward terminal exhaustion, indicating that mitochondrial deregulation caused T cell exhaustion. Furthermore, supplementation with nicotinamide riboside enhanced T cell mitochondrial fitness and improved responsiveness to anti-PD-1 treatment. Together, our results reveal insights into how mitochondrial dynamics and quality orchestrate T cell antitumor responses and commitment to the exhaustion program.
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Affiliation(s)
- Yi-Ru Yu
- Department of Oncology, University of Lausanne, Lausanne, Switzerland.,Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland
| | - Hana Imrichova
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Haiping Wang
- Department of Oncology, University of Lausanne, Lausanne, Switzerland.,Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland
| | - Tung Chao
- Department of Oncology, University of Lausanne, Lausanne, Switzerland.,Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland
| | - Zhengtao Xiao
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
| | - Min Gao
- Institute of Bioengineering, Institute of Materials Science and Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Marcela Rincon-Restrepo
- Department of Oncology, University of Lausanne, Lausanne, Switzerland.,Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland
| | - Fabien Franco
- Department of Oncology, University of Lausanne, Lausanne, Switzerland.,Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland
| | - Raphael Genolet
- Department of Oncology, University of Lausanne, Lausanne, Switzerland.,Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland
| | - Wan-Chen Cheng
- Department of Oncology, University of Lausanne, Lausanne, Switzerland.,Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland
| | - Camilla Jandus
- Department of Oncology, University of Lausanne, Lausanne, Switzerland.,Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland
| | - George Coukos
- Department of Oncology, University of Lausanne, Lausanne, Switzerland.,Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland
| | - Yi-Fan Jiang
- Graduate Institute of Molecular and Comparative Pathobiology, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan
| | - Jason W Locasale
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
| | - Alfred Zippelius
- Department of Biomedicine, Laboratory Cancer Immunology, University Hospital and University of Basel, Basel, Switzerland.,Medical Oncology, University Hospital Basel, Basel, Switzerland
| | - Pu-Ste Liu
- Institute of Cellular and System Medicine, National Health Research Institute, Miaoli County, Taiwan
| | - Li Tang
- Institute of Bioengineering, Institute of Materials Science and Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Christoph Bock
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.,Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
| | - Nicola Vannini
- Department of Oncology, University of Lausanne, Lausanne, Switzerland.,Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland
| | - Ping-Chih Ho
- Department of Oncology, University of Lausanne, Lausanne, Switzerland. .,Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland.
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5
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Franco F, Jaccard A, Romero P, Yu YR, Ho PC. Metabolic and epigenetic regulation of T-cell exhaustion. Nat Metab 2020; 2:1001-1012. [PMID: 32958939 DOI: 10.1038/s42255-020-00280-9] [Citation(s) in RCA: 163] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Accepted: 08/12/2020] [Indexed: 12/13/2022]
Abstract
Current immunotherapies yield remarkable clinical outcomes by boosting the power of host immunity in cancer cell elimination and viral clearance. However, after prolonged antigen exposure, CD8+ T cells differentiate into a special differentiation state known as T-cell exhaustion, which poses one of the major hurdles to antiviral and antitumor immunity during chronic viral infection and tumour development. Growing evidence indicates that exhausted T cells undergo metabolic insufficiency with altered signalling cascades and epigenetic landscapes, which dampen effector immunity and cause poor responsiveness to immune-checkpoint-blockade therapies. How metabolic stress affects T-cell exhaustion remains unclear; therefore, in this Review, we summarize current knowledge of how T-cell exhaustion occurs, and discuss how metabolic insufficiency and prolonged stress responses may affect signalling cascades and epigenetic reprogramming, thus locking T cells into an exhausted state via specialized differentiation programming.
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Affiliation(s)
- Fabien Franco
- Department of Fundamental Oncology, University of Lausanne, Lausanne, Switzerland
- Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland
| | - Alison Jaccard
- Department of Fundamental Oncology, University of Lausanne, Lausanne, Switzerland
- Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland
| | - Pedro Romero
- Department of Fundamental Oncology, University of Lausanne, Lausanne, Switzerland
- Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland
| | - Yi-Ru Yu
- Department of Fundamental Oncology, University of Lausanne, Lausanne, Switzerland.
- Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland.
| | - Ping-Chih Ho
- Department of Fundamental Oncology, University of Lausanne, Lausanne, Switzerland.
- Ludwig Institute for Cancer Research, University of Lausanne, Epalinges, Switzerland.
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Mushtaq G, Greig NH, Anwar F, Al-Abbasi FA, Zamzami MA, Al-Talhi HA, Kamal MA. Neuroprotective Mechanisms Mediated by CDK5 Inhibition. Curr Pharm Des 2016; 22:527-34. [PMID: 26601962 DOI: 10.2174/1381612822666151124235028] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Accepted: 11/24/2015] [Indexed: 12/30/2022]
Abstract
Cyclin-dependent kinase 5 (CDK5) is a proline-directed serine/threonine kinase belonging to the family of cyclin-dependent kinases. In addition to maintaining the neuronal architecture, CDK5 plays an important role in the regulation of synaptic plasticity, neurotransmitter release, neuron migration and neurite outgrowth. Although various reports have shown links between neurodegeneration and deregulation of cyclin-dependent kinases, the specific role of CDK5 inhibition in causing neuroprotection in cases of neuronal insult or in neurodegenerative diseases is not wellunderstood. This article discusses current evidence for the involvement of CDK5 deregulation in neurodegenerative disorders and neurodegeneration associated with stroke through various mechanisms. These include upregulation of cyclin D1 and overactivation of CDK5 mediated neuronal cell death pathways, aberrant hyperphosphorylation of human tau proteins and/or neurofilament proteins, formation of neurofibrillary lesions, excitotoxicity, cytoskeletal disruption, motor neuron death (due to abnormally high levels of CDK5/p25) and colchicine- induced apoptosis in cerebellar granule neurons. A better understanding of the role of CDK5 inhibition in neuroprotective mechanisms will help scientists and researchers to develop selective, safe and efficacious pharmacological inhibitors of CDK5 for therapeutic use against human neurodegenerative disorders, such as Alzheimer's disease, amyotrophic lateral sclerosis and neuronal loss associated with stroke.
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Affiliation(s)
- Gohar Mushtaq
- Department of Biochemistry, College of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
| | - Nigel H Greig
- Drug Design & Development Section, Translational Gerontology Branch, Intramural Research Program, National, Institute on Aging, National Institutes of Health, Biomedical Research Center, 251 Bayview Boulevard, Baltimore, MD 21224, USA.
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Short-Term Differentiation of Glioblastoma Stem Cells Induces Hypoxia Tolerance. Neurochem Res 2016; 41:1545-58. [PMID: 26915110 PMCID: PMC4893075 DOI: 10.1007/s11064-016-1868-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 02/03/2016] [Accepted: 02/08/2016] [Indexed: 01/28/2023]
Abstract
Glioblastoma is the most common and malignant brain cancer. In spite of surgical removal, radiation and chemotherapy, this cancer recurs within short time and median survival after diagnosis is less than a year. Glioblastoma stem cells (GSCs) left in the brain after surgery is thought to explain the inevitable recurrence of the tumor. Although hypoxia is a prime factor contributing to treatment resistance in many cancers, its effect on GSC has been little studied. Especially how differentiation influences the tolerance to acute hypoxia in GSCs is not well explored. We cultured GSCs from three patient biopsies and exposed these and their differentiated (1- and 4-weeks) progeny to acute hypoxia while monitoring intracellular calcium and mitochondrial membrane potential (ΔΨm). Undifferentiated GSCs were not hypoxia tolerant, showing both calcium overload and mitochondrial depolarization. One week differentiated cells were the most tolerant to hypoxia, preserving intracellular calcium stability and ΔΨm during 15 min of acute hypoxia. After 4 weeks of differentiation, mitochondrial mass was significantly reduced. In these cells calcium homeostasis was maintained during hypoxia, although the mitochondria were depolarized, suggesting a reduced mitochondrial dependency. Basal metabolic rate increased by differentiation, however, low oxygen consumption and high ΔΨm in undifferentiated GSCs did not provide hypoxia tolerance. The results suggest that undifferentiated GSCs are oxygen dependent, and that limited differentiation induces relative hypoxia tolerance. Hypoxia tolerance may be a factor involved in high-grade malignancy. This warrants a careful approach to differentiation as a glioblastoma treatment strategy.
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Lukyanova LD, Kirova YI. Mitochondria-controlled signaling mechanisms of brain protection in hypoxia. Front Neurosci 2015; 9:320. [PMID: 26483619 PMCID: PMC4589588 DOI: 10.3389/fnins.2015.00320] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 08/27/2015] [Indexed: 01/06/2023] Open
Abstract
The article is focused on the role of the cell bioenergetic apparatus, mitochondria, involved in development of immediate and delayed molecular mechanisms for adaptation to hypoxic stress in brain cortex. Hypoxia induces reprogramming of respiratory chain function and switching from oxidation of NAD-related substrates (complex I) to succinate oxidation (complex II). Transient, reversible, compensatory activation of respiratory chain complex II is a major mechanism of immediate adaptation to hypoxia necessary for (1) succinate-related energy synthesis in the conditions of oxygen deficiency and formation of urgent resistance in the body; (2) succinate-related stabilization of HIF-1α and initiation of its transcriptional activity related with formation of long-term adaptation; (3) succinate-related activation of the succinate-specific receptor, GPR91. This mechanism participates in at least four critical regulatory functions: (1) sensor function related with changes in kinetic properties of complex I and complex II in response to a gradual decrease in ambient oxygen concentration; this function is designed for selection of the most efficient pathway for energy substrate oxidation in hypoxia; (2) compensatory function focused on formation of immediate adaptive responses to hypoxia and hypoxic resistance of the body; (3) transcriptional function focused on activated synthesis of HIF-1 and the genes providing long-term adaptation to low pO2; (4) receptor function, which reflects participation of mitochondria in the intercellular signaling system via the succinate-dependent receptor, GPR91. In all cases, the desired result is achieved by activation of the succinate-dependent oxidation pathway, which allows considering succinate as a signaling molecule. Patterns of mitochondria-controlled activation of GPR-91- and HIF-1-dependent reaction were considered, and a possibility of their participation in cellular-intercellular-systemic interactions in hypoxia and adaptation was proved.
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Affiliation(s)
- Ludmila D. Lukyanova
- Laboratory for Bioenergetics and Hypoxia, Institute of General Pathology and PathophysiologyMoscow, Russia
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Abstract
Ischemic stroke is one of the leading causes of morbidity and mortality. Treatment options are limited and only a minority of patients receive acute interventions. Understanding the mechanisms that mediate neuronal injury and death may identify targets for neuroprotective treatments. Here we show that the aberrant activity of the protein kinase Cdk5 is a principal cause of neuronal death in rodents during stroke. Ischemia induced either by embolic middle cerebral artery occlusion (MCAO) in vivo or by oxygen and glucose deprivation in brain slices caused calpain-dependent conversion of the Cdk5-activating cofactor p35 to p25. Inhibition of aberrant Cdk5 during ischemia protected dopamine neurotransmission, maintained field potentials, and blocked excitotoxicity. Furthermore, pharmacological inhibition or conditional knock-out (CKO) of Cdk5 prevented neuronal death in response to ischemia. Moreover, Cdk5 CKO dramatically reduced infarctions following MCAO. Thus, targeting aberrant Cdk5 activity may serve as an effective treatment for stroke.
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10
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Enhancement of ethanol fermentation in Saccharomyces cerevisiae sake yeast by disrupting mitophagy function. Appl Environ Microbiol 2013; 80:1002-12. [PMID: 24271183 DOI: 10.1128/aem.03130-13] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Saccharomyces cerevisiae sake yeast strain Kyokai no. 7 has one of the highest fermentation rates among brewery yeasts used worldwide; therefore, it is assumed that it is not possible to enhance its fermentation rate. However, in this study, we found that fermentation by sake yeast can be enhanced by inhibiting mitophagy. We observed mitophagy in wild-type sake yeast during the brewing of Ginjo sake, but not when the mitophagy gene (ATG32) was disrupted. During sake brewing, the maximum rate of CO2 production and final ethanol concentration generated by the atg32Δ laboratory yeast mutant were 7.50% and 2.12% higher than those of the parent strain, respectively. This mutant exhibited an improved fermentation profile when cultured under limiting nutrient concentrations such as those used during Ginjo sake brewing as well as in minimal synthetic medium. The mutant produced ethanol at a concentration that was 2.76% higher than the parent strain, which has significant implications for industrial bioethanol production. The ethanol yield of the atg32Δ mutant was increased, and its biomass yield was decreased relative to the parent sake yeast strain, indicating that the atg32Δ mutant has acquired a high fermentation capability at the cost of decreasing biomass. Because natural biomass resources often lack sufficient nutrient levels for optimal fermentation, mitophagy may serve as an important target for improving the fermentative capacity of brewery yeasts.
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Li J, Qu Y, Chen D, Zhang L, Zhao F, Luo L, Pan L, Hua J, Mu D. The neuroprotective role and mechanisms of TERT in neurons with oxygen-glucose deprivation. Neuroscience 2013; 252:346-58. [PMID: 23968592 DOI: 10.1016/j.neuroscience.2013.08.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 07/24/2013] [Accepted: 08/09/2013] [Indexed: 01/14/2023]
Abstract
Telomerase reverse transcriptase (TERT) is reported to protect neurons from apoptosis induced by various stresses including hypoxia-ischemia (HI). However, the mechanisms by which TERT exerts its anti-apoptotic role in neurons with HI injury remain unclear. In this study, we examined the protective role and explored the possible mechanisms of TERT in neurons with HI injury in vitro. Primary cultured neurons were exposed to oxygen and glucose deprivation (OGD) for 3h followed by reperfusion to mimic HI injury in vivo. Plasmids containing TERT antisense, sense nucleotides, or mock were transduced into neurons at 48h before OGD. Expression and distribution of TERT were measured by immunofluorescence labeling and western blot. The expression of cleaved caspase 3 (CC3), Bcl-2 and Bax were detected by western blot. Neuronal apoptosis was measured with terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL). The mitochondrial reactive oxygen species (ROS) were measured by MitoSOX Red staining. Fluorescent probe JC-1 was used to measure the mitochondrial membrane potential (ΔΨm). We found that TERT expression increased at 8h and peaked at 24h in neurons after OGD. CC3 expression and neuronal apoptosis were induced and peaked at 24h after OGD. TERT inhibition significantly increased CC3 expression and neuronal apoptosis after OGD treatment. Additionally, TERT inhibition decreased the expression ratio of Bcl-2/Bax, and enhanced ROS production and ΔΨm dissipation after OGD. These data suggest that TERT plays a neuroprotective role via anti-apoptosis in neurons after OGD. The underlying mechanisms may be associated with regulating Bcl-2/Bax expression ratio, attenuating ROS generation, and increasing mitochondrial membrane potential.
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Affiliation(s)
- J Li
- Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu 610041, China; Key Laboratory of Obstetric & Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, Sichuan University, 610041 Chengdu, Sichuan, China
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12
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Yu Z, Liu N, Liu J, Yang K, Wang X. Neuroglobin, a novel target for endogenous neuroprotection against stroke and neurodegenerative disorders. Int J Mol Sci 2012; 13:6995-7014. [PMID: 22837676 PMCID: PMC3397508 DOI: 10.3390/ijms13066995] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2012] [Revised: 05/25/2012] [Accepted: 05/31/2012] [Indexed: 11/16/2022] Open
Abstract
Brain neurons and tissues respond to sublethal injury by activating endogenous protective pathways. Recently, following the failure of a large number of clinical trials for protective strategies against stroke that aim to inhibit a specific ischemia response pathway, endogenous neuroprotection has emerged as a more promising and hopeful strategy for development of therapeutics against stroke and neurodegenerative disorders. Neuroglobin (Ngb) is an oxygen-binding globin protein that is highly and specifically expressed in brain neurons. Accumulating evidence have clearly demonstrated that Ngb is an endogenous neuroprotective molecule against hypoxic/ischemic and oxidative stress-related insults in cultured neurons and animals, as well as neurodegenerative disorders such as Alzheimer’s disease, thus any pharmacological strategy that can up-regulate endogenous Ngb expression may lead to novel therapeutics against these brain disorders. In this review, we summarize recent studies about the biological function, regulation of gene expression, and neuroprotective mechanisms of Ngb. Furthermore, strategies for identification of chemical compounds that can up-regulate endogenous Ngb expression for neuroprotection against stroke and neurodegenerative disorders are discussed.
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Affiliation(s)
- Zhanyang Yu
- Neuroprotection Research Laboratory, Department of Neurology and Radiology, Massachusetts General Hospital, Neuroscience Program, Harvard Medical School, Room 2401/2411A, 149 13th Street, Charlestown Boston, MA 02129, USA; E-Mails: (N.L.); (K.Y.)
- Authors to whom correspondence should be addressed; E-Mails: (Z.Y.); (X.W.); Tel.: +1-617-724-9503 (Z.Y.); +1-617-724-9513 (X.W.); Fax: +1-617-726-7830 (Z.Y.); +1-617-726-7830 (X.W.)
| | - Ning Liu
- Neuroprotection Research Laboratory, Department of Neurology and Radiology, Massachusetts General Hospital, Neuroscience Program, Harvard Medical School, Room 2401/2411A, 149 13th Street, Charlestown Boston, MA 02129, USA; E-Mails: (N.L.); (K.Y.)
| | - Jianxiang Liu
- National Institute for Radiological Protection, China Center for Disease Control and Prevention, Beijing 100088, China; E-Mail:
| | - Kevin Yang
- Neuroprotection Research Laboratory, Department of Neurology and Radiology, Massachusetts General Hospital, Neuroscience Program, Harvard Medical School, Room 2401/2411A, 149 13th Street, Charlestown Boston, MA 02129, USA; E-Mails: (N.L.); (K.Y.)
| | - Xiaoying Wang
- Neuroprotection Research Laboratory, Department of Neurology and Radiology, Massachusetts General Hospital, Neuroscience Program, Harvard Medical School, Room 2401/2411A, 149 13th Street, Charlestown Boston, MA 02129, USA; E-Mails: (N.L.); (K.Y.)
- Authors to whom correspondence should be addressed; E-Mails: (Z.Y.); (X.W.); Tel.: +1-617-724-9503 (Z.Y.); +1-617-724-9513 (X.W.); Fax: +1-617-726-7830 (Z.Y.); +1-617-726-7830 (X.W.)
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Protein kinase C beta in postischemic brain mitochondria. Mitochondrion 2012; 12:138-43. [DOI: 10.1016/j.mito.2011.06.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 04/06/2011] [Accepted: 06/10/2011] [Indexed: 11/23/2022]
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14
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Neuroglobin: A Novel Target for Endogenous Neuroprotection. Transl Stroke Res 2012. [DOI: 10.1007/978-1-4419-9530-8_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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15
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Tokunaga S, Araki T. Wallerian degeneration slow mouse neurons are protected against cell death caused by mechanisms involving mitochondrial electron transport dysfunction. J Neurosci Res 2011; 90:664-71. [DOI: 10.1002/jnr.22792] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 08/08/2011] [Accepted: 08/22/2011] [Indexed: 01/18/2023]
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16
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Dave KR, Pileggi A, Raval AP. Recurrent hypoglycemia increases oxygen glucose deprivation-induced damage in hippocampal organotypic slices. Neurosci Lett 2011; 496:25-9. [PMID: 21466838 DOI: 10.1016/j.neulet.2011.03.079] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 03/24/2011] [Accepted: 03/25/2011] [Indexed: 11/15/2022]
Abstract
More than 65% of mortality among diabetics is due to stroke and heart disease. The major side effect of intensive therapy in both type 1 and type 2 diabetics is recurrent hypoglycemic episodes (RH). Our previous study in a rat model of insulin-requiring diabetes indicated that RH exacerbates cerebral ischemic damage. Studies related to RH in hypoglycemia unawareness suggest that RH may be deleterious to outcome following cerebral ischemia owing to systemic effects, since hormonal response to hypoglycemia is impaired following RH. The goal of the present study was to determine if RH increases oxygen-glucose deprivation (OGD)-induced damage in hippocampal organotypic slices, which are devoid of systemic influence. Hippocampal slices cultured in ex vivo conditions for 9-10 days were exposed to ten 30-min episodes of "hypoglucose" (to mimic the hypoglycemic condition) medium (1.06 mM) twice a day. Slices were exposed to OGD 12h after the last hypo/normo-glucose exposure. OGD in control slices resulted in 60% neuronal death. The percentage of cell death in RH-treated slices was significantly higher by 24% than in control slices. The results demonstrate that RH can affect brain cells in the absence of humoral influence. In conclusion, the previous exposure of hippocampal slices to RH exacerbates OGD-induced damage. Understanding the mechanism by which RH increases ischemic damage in diabetics will help improve outcome following stroke.
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Affiliation(s)
- Kunjan R Dave
- Cerebral Vascular Disease Research Center, Department of Neurology, 1420 NW 9th Ave., TSL/203E, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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17
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Isaev NK, Stelmashook EV, Dirnagl U, Plotnikov EY, Kuvshinova EA, Zorov DB. Mitochondrial free radical production induced by glucose deprivation in cerebellar granule neurons. BIOCHEMISTRY (MOSCOW) 2011; 73:149-55. [DOI: 10.1134/s0006297908020053] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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18
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Fung SJ, Xi MC, Zhang JH, Yamuy J, Sampogna S, Tsai KL, Lim V, Morales FR, Chase MH. Eszopiclone prevents excitotoxicity and neurodegeneration in the hippocampus induced by experimental apnea. Sleep 2010; 32:1593-601. [PMID: 20041595 DOI: 10.1093/sleep/32.12.1593] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
STUDY OBJECTIVE This study was designed to determine the effects of eszopiclone on apnea-induced excitotoxic synaptic processes and apoptosis in the hippocampus. DESIGN Recurrent periods of apnea, which consisted of a sequence of apnea (75% SpO2), followed by ventilation with recovery to normoxia (> 95% SpO2), were induced for a period of three hours in anesthetized guinea pigs. The CA3 Schaffer collateral pathway in the hippocampus was stimulated and the field excitatory postsynaptic potential (fEPSP) response was recorded in CA1. Animals in the experimental group received an intravenous injection of eszopiclone (3 mg/kg) 10 min prior to the initiation of the periods of recurrent apnea, and once every 60 min thereafter; control animals received comparable injections of vehicle. At the end of the 3-h period of recurrent apnea, the animals were perfused, and hippocampal sections were immunostained in order to determine the presence of apoptosis, i.e., programmed cell death. ANALYSES AND RESULTS: Apnea resulted in a persistent increase in synaptic responsiveness of CA1 neurons as determined by analyses of the fEPSP. Eszopiclone antagonized the apnea-induced increase in the fEPSP. Morphological analyses revealed significant apoptosis of CA1 neurons in control animals; however, there was no significant apoptosis in eszopiclone-treated animals. CONCLUSIONS Eszopiclone was determined to suppress the apnea-induced hyperexcitability of hippocampal CA1 neurons, thereby reducing/eliminating neurotoxicity. These data lend credence to our hypothesis that eszopiclone, exclusive of its hypnotic actions, has the capacity to function as a potent neuroprotective agent.
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Affiliation(s)
- Simon J Fung
- WebSciences International, 1251 Westwood Blvd., Los Angeles, CA 90024, USA.
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19
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Stelmashook EV, Isaev NK, Plotnikov EY, Uzbekov RE, Alieva IB, Arbeille B, Zorov DB. Effect of transitory glucose deprivation on mitochondrial structure and functions in cultured cerebellar granule neurons. Neurosci Lett 2009; 461:140-4. [DOI: 10.1016/j.neulet.2009.05.073] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2009] [Revised: 05/18/2009] [Accepted: 05/27/2009] [Indexed: 10/20/2022]
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20
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Kowalczyk JE, Beresewicz M, Gajkowska B, Zabłocka B. Association of protein kinase C delta and phospholipid scramblase 3 in hippocampal mitochondria correlates with neuronal vulnerability to brain ischemia. Neurochem Int 2009; 55:157-63. [PMID: 19428821 DOI: 10.1016/j.neuint.2009.01.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 01/07/2009] [Accepted: 01/14/2009] [Indexed: 02/04/2023]
Abstract
Recent findings support the idea that mitochondrial integrity plays an important role in the propagation of excitotoxic ischemic signal and PKC is implicated in the regulation of mitochondrial membranes properties. One of the targets of PKC delta is phospholipid scramblase 3 (PLSCR3), an enzyme responsible for cardiolipin translocation from the inner to outer mitochondrial membrane. To get an insight into in vivo mechanism by which PKC delta mediates ischemia/reperfusion injury of hippocampal neurons, we examined the effects of transient brain ischemia in gerbil on association of PKC delta with mitochondria isolated from ischemia-vulnerable (CA1) and ischemia-resistant regions, and interactions between PKC delta and PLSCR3. Postischemic, biphasic and brain region-specific translocation of PKC delta to mitochondria was observed. First peak was at 30-60 min of reperfusion and the second was observed after 72-96 h following ischemia. PKC delta was translocated to mitochondria only in CA1 region. The PLSCR3 mRNA and protein was detected in brain by RT-PCR and sequence analysis, Western blotting and immunocytochemistry in electron microscopy (EM). Co-immunoprecipitation and double-labeled immuno-EM showed association of PKC delta and PLSCR3 in postischemic CA1 mitochondria. Additionally, the amount of tBid associated with mitochondria was elevated 96 h following ischemia. Our data suggest that in the postischemic brain PKC delta co-localizes with PLSCR3 in mitochondria and this event might influence the mitochondrial membranes architecture and delayed neurons degeneration.
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Affiliation(s)
- Joanna E Kowalczyk
- Molecular Biology Unit, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
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21
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Louie K, Russo GJ, Salkoff DB, Wellington A, Zinsmaier KE. Effects of imaging conditions on mitochondrial transport and length in larval motor axons of Drosophila. Comp Biochem Physiol A Mol Integr Physiol 2008; 151:159-72. [PMID: 18639643 DOI: 10.1016/j.cbpa.2008.06.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 06/17/2008] [Accepted: 06/18/2008] [Indexed: 10/21/2022]
Abstract
The distribution of mitochondria is sensitive to physiological stresses and changes in metabolic demands. Consequently, it is important to carefully define the conditions facilitating live imaging of mitochondrial transport in dissected animal preparations. In this study, we examined Schneider's and the haemolymph-like solutions HL3 and HL6 for their suitability to image mitochondrial transport in motor axons of dissected Drosophila melanogaster larvae. Overall, mitochondrial transport kinetics in larval motor axons appeared similar among all three solutions. Unexpectedly, HL3 solution selectively increased the length of mitochondria in the context of the net-direction of transport. We also found that mitochondrial transport is sensitive to the extracellular Ca(2+) but not glutamate concentration. High concentrations of extracellular glutamate affected only the ratio between motile and stationary mitochondria. Our study offers a valuable overview of mitochondrial transport kinetics in larval motor axons of Drosophila under various conditions, guiding future studies genetically dissecting mechanisms of mitochondrial transport.
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Affiliation(s)
- Kathryn Louie
- Arizona Research Laboratories Division of Neurobiology, University of Arizona, Tucson, AZ 85721, USA
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22
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Larsen GA, Skjellegrind HK, Vinje ML, Berg-Johnsen J. Mitochondria are More Resistant to Hypoxic Depolarization in the Newborn than in the Adult Brain. Neurochem Res 2008; 33:1894-900. [DOI: 10.1007/s11064-008-9664-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Accepted: 03/11/2008] [Indexed: 11/29/2022]
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23
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Kang L, Sanders NM, Dunn-Meynell AA, Gaspers LD, Routh VH, Thomas AP, Levin BE. Prior hypoglycemia enhances glucose responsiveness in some ventromedial hypothalamic glucosensing neurons. Am J Physiol Regul Integr Comp Physiol 2008; 294:R784-92. [DOI: 10.1152/ajpregu.00645.2007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Antecedent insulin-induced hypoglycemia (IIH) reduces adrenomedullary responses (AMR) to subsequent bouts of hypoglycemia. The ventromedial hypothalamus [VMH: arcuate (ARC) + ventromedial nuclei] contains glucosensing neurons, which are thought to be mediators of these AMR. Since type 1 diabetes mellitus often begins in childhood, we used juvenile (4- to 5-wk-old) rats to demonstrate that a single bout of IIH (5 U/kg sc) reduced plasma glucose by 24% and peak epinephrine by 59% 1 day later. This dampened AMR was associated with 46% higher mRNA for VMH glucokinase, a key mediator of neuronal glucosensing. Compared with neurons from saline-injected rats, ventromedial nucleus glucose-excited neurons from insulin-injected rats demonstrated a leftward shift in their glucose responsiveness (EC50= 0.45 and 0.10 mmol/l for saline and insulin, respectively, P = 0.05) and a 31% higher maximal activation by glucose ( P = 0.05), although this maximum occurred at a higher glucose concentration (saline, 0.7 vs. insulin, 1.5 mmol/l). Although EC50values did not differ, ARC glucose-excited neurons had 19% higher maximal activation, which occurred at a lower glucose concentration in insulin- than saline-injected rats (saline, 2.5 vs. insulin, 1.5 mmol/l). In addition, ARC glucose-inhibited neurons from insulin-injected rats were maximally inhibited at a fivefold lower glucose concentration (saline, 2.5 vs. insulin, 0.5 mmol/l), although this inhibition declined at >0.5 mmol/l glucose. These data suggest that the increased VMH glucokinase after IIH may contribute to the increased responsiveness of VMH glucosensing neurons to glucose and the associated blunting of the AMR.
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Quinolinate-induced rat striatal excitotoxicity impairs endoplasmic reticulum Ca2+-ATPase function. Neurochem Res 2008; 33:1749-58. [PMID: 18307036 DOI: 10.1007/s11064-008-9619-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Accepted: 01/30/2008] [Indexed: 10/22/2022]
Abstract
Excessive activation of NMDA glutamate receptors and the resulting loss of intracellular Ca(2+) homeostasis may be lethal (excitotoxic) to neurons. Such excitotoxicity can be induced in vivo by intrastriatal infusion of quinolinate, as this substance selectively activates NMDA receptors. The aim of the present research was to investigate whether the in vivo treatment of striatal tissue with quinolinate would lead to an early impairment of sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) activity or mitochondrial Ca(2+) sequestration, two intracellular mechanisms involved in Ca(2+) homeostasis and signaling. Sodium quinolinate was infused intrastriatally into adult rats, and 6 h later the brains were removed and the corpora striata dissected. At this time point, striatal sections stained with Fluoro-Jade, a cellular marker of cell death, showed initial signs of neuronal degeneration. In addition, SERCA activity decreased 39% in relation to the activity observed in the control striata. A corresponding decrease of the same magnitude in (45)Ca(2+) uptake by striatal microsomes was also found in the treated striata. Western blot analysis did not indicate any decrease in SERCA levels in striatal tissue after quinolinate infusion. Mitochondrial Ca(2+) sequestration was still preserved in quinolinate-treated striatal tissue when the assay was carried out in the presence of physiological concentrations of ATP and Mg(2+). These results suggest that impairment of the SERCA function may be an early event in excitotoxicity.
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25
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Kobayashi K, Xin Y, Ymer SI, Werther GA, Russo VC. Subtractive hybridisation screen identifies genes regulated by glucose deprivation in human neuroblastoma cells. Brain Res 2007; 1170:129-39. [PMID: 17719568 DOI: 10.1016/j.brainres.2007.07.042] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 07/24/2007] [Accepted: 07/25/2007] [Indexed: 02/06/2023]
Abstract
Glucose is the major source of energy for the brain and inadequate glucose supply causes damage of neuronal cells. In this study we employed the human neuroblastoma cell line SH-SY5Y, as an in vitro model for neuronal cells, to identify genes regulated by glucose deprivation. Using subtractive hybridisation screen, validated by Northern analysis, we identify for the first time specific targets of the glucopenic response. These genes are involved in key cellular process including gene transcription, protein synthesis, mitochondrial metabolism, neuronal development, neuroprotection and neuronal apoptosis. Our findings suggest that the fate of neuronal cells undergoing glucose starvation relies on complex gene interactions. Modulation of the expression of these genes in vivo will enable determination of the precise role of each gene and possibly identify key elements and potential therapeutic targets of the glucopenic response.
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Affiliation(s)
- Kisho Kobayashi
- Centre for Hormone Research, Murdoch Children's Research Institute, Department of Paediatrics, University of Melbourne, Royal Children's Hospital, 3052 Parkville, Australia
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26
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Gu XQ, Siemen D, Parvez S, Cheng Y, Xue J, Zhou D, Sun X, Jonas EA, Haddad GG. Hypoxia increases BK channel activity in the inner mitochondrial membrane. Biochem Biophys Res Commun 2007; 358:311-6. [PMID: 17481584 DOI: 10.1016/j.bbrc.2007.04.110] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Accepted: 04/19/2007] [Indexed: 10/23/2022]
Abstract
To explore the potential function of the BK channel in the inner mitochondrial membrane under physiological and hypoxic conditions, we used on-mitoplast and whole-mitoplast patches. Single BK channels had a conductance of 276+/-9 pS under symmetrical K(+) solutions, were Ca(2+)- and voltage-dependent and were inhibited by 0.1 microM charybdotoxin. In response to hypoxia, BK increased open probability, shifted its reversal potential (9.3+/-2.4 mV) in the positive direction and did not change its conductance. We conclude that (1) the properties at rest of this mitoplast K(+) channel are similar to those of BK channels in the plasma membrane; (2) hypoxia induces an increase, rather than a decrease (as in the plasmalemma), in the open probability of this K(+) channel, leading to K(+) efflux from the mitochondrial matrix to the outside. We speculate that this increase in K(+) efflux from mitochondria into the cytosol is important during hypoxia in maintaining cytosolic K(+).
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Affiliation(s)
- Xiang Q Gu
- Department of Pediatrics (Section of Respiratory Medicine), University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0735, USA
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27
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Isaev NK, Stel'mashuk EV, Zorov DB. Cellular mechanisms of brain hypoglycemia. BIOCHEMISTRY (MOSCOW) 2007; 72:471-8. [PMID: 17573700 DOI: 10.1134/s0006297907050021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Data on intracellular processes induced by a low glucose level in nerve tissue are presented. The involvement of glutamate and adenosine receptors, mitochondria, reactive oxygen species (ROS), and calcium ions in the development of hypoglycemia-induced damage of neurons is considered. Hypoglycemia-induced calcium overload of neuronal mitochondria is suggested to be responsible for the increased ROS production by mitochondria.
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Affiliation(s)
- N K Isaev
- Belozersky Institute of Physico-Nhemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia.
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28
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Centonze D, Rossi S, Tortiglione A, Picconi B, Prosperetti C, De Chiara V, Bernardi G, Calabresi P. Synaptic plasticity during recovery from permanent occlusion of the middle cerebral artery. Neurobiol Dis 2007; 27:44-53. [PMID: 17490888 DOI: 10.1016/j.nbd.2007.03.012] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Revised: 03/15/2007] [Accepted: 03/31/2007] [Indexed: 11/23/2022] Open
Abstract
Synaptic rearrangements in the peri-infarct regions are believed to contribute to the partial recovery of function that takes place after stroke. Here, we performed neurophysiological recordings from single neurons of rats with permanent occlusion of the middle cerebral artery (pMCAO) during the resolution of their neurological deficits. Our results show that complex and dynamic changes of glutamate transmission in the peri-infarct area parallel the recovery from brain infarct. We have observed that frequency and duration of spontaneous glutamate-mediated synaptic events were markedly increased in striatal neurons during the early phase of the recovery (3 days after pMCAO), due to potentiation of both NMDA (N-methyl-d-aspartate) and non-NMDA receptor-mediated transmission. In the late phase of recovery (7 days after pMCAO), glutamate transmission was still enhanced because of a selective facilitation of non-NMDA receptor-mediated transmission. Spiny projection neurons but not aspiny interneurons underwent detectable changes of synaptic excitability in the striatum following pMCAO, indicating that the process of neuronal adaptation after focal brain ischemia is cell-type-specific. Our results provide a synaptic correlate of the long-lasting brain hyperexcitability mediating recovery described with noninvasive neurophysiological approaches.
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Affiliation(s)
- Diego Centonze
- Clinica Neurologica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy.
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