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Alva R, Wiebe JE, Stuart JA. Revisiting reactive oxygen species production in hypoxia. Pflugers Arch 2024; 476:1423-1444. [PMID: 38955833 DOI: 10.1007/s00424-024-02986-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 06/20/2024] [Accepted: 06/24/2024] [Indexed: 07/04/2024]
Abstract
Cellular responses to hypoxia are crucial in various physiological and pathophysiological contexts and have thus been extensively studied. This has led to a comprehensive understanding of the transcriptional response to hypoxia, which is regulated by hypoxia-inducible factors (HIFs). However, the detailed molecular mechanisms of HIF regulation in hypoxia remain incompletely understood. In particular, there is controversy surrounding the production of mitochondrial reactive oxygen species (ROS) in hypoxia and how this affects the stabilization and activity of HIFs. This review examines this controversy and attempts to shed light on its origin. We discuss the role of physioxia versus normoxia as baseline conditions that can affect the subsequent cellular response to hypoxia and highlight the paucity of data on pericellular oxygen levels in most experiments, leading to variable levels of hypoxia that might progress to anoxia over time. We analyze the different outcomes reported in isolated mitochondria, versus intact cells or whole organisms, and evaluate the reliability of various ROS-detecting tools. Finally, we examine the cell-type and context specificity of oxygen's various effects. We conclude that while recent evidence suggests that the effect of hypoxia on ROS production is highly dependent on the cell type and the duration of exposure, efforts should be made to conduct experiments under carefully controlled, physiological microenvironmental conditions in order to rule out potential artifacts and improve reproducibility in research.
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Affiliation(s)
- Ricardo Alva
- Department of Biological Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada.
| | - Jacob E Wiebe
- Department of Biological Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada
| | - Jeffrey A Stuart
- Department of Biological Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada.
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2
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Cerutti L, Brofiga M. Unraveling brain diseases: The promise of brain-on-a-chip models. J Neurosci Methods 2024; 405:110105. [PMID: 38460796 DOI: 10.1016/j.jneumeth.2024.110105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 02/23/2024] [Accepted: 03/03/2024] [Indexed: 03/11/2024]
Abstract
Brain disorders, encompassing a wide spectrum of neurological and psychiatric conditions, present a formidable challenge in modern medicine. Despite decades of research, the intricate complexity of the human brain still eludes comprehensive understanding, impeding the development of effective treatments. Recent advancements in microfluidics and tissue engineering have led to the development of innovative platforms known as "Brain-on-a-Chip" (BoC) i.e., advanced in vitro systems that aim to replicate the microenvironment of the brain with the highest possible fidelity. This technology offers a promising test-bed for studying brain disorders at the cellular and network levels, providing insights into disease mechanisms, drug screening, and, in perspective, the development of personalized therapeutic strategies. In this review, we provide an overview of the BoC models developed over the years to model and understand the onset and progression of some of the most severe neurological disorders in terms of incidence and debilitation (stroke, Parkinson's, Alzheimer's, and epilepsy). We also report some of the cutting-edge therapeutic approaches whose effects were evaluated by means of these technologies. Finally, we discuss potential challenges, and future perspectives of the BoC models.
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Affiliation(s)
- Letizia Cerutti
- Department of Informatics, Bioengineering, Robotics, and Systems Engineering (DIBIRS), University of Genova, Genova, Italy
| | - Martina Brofiga
- Department of Informatics, Bioengineering, Robotics, and Systems Engineering (DIBIRS), University of Genova, Genova, Italy; ScreenNeuroPharm s.r.l, Sanremo, Italy; Neurofacility, Istituto Italiano di Tecnologia, Genova, Italy.
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3
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Meyer K, Ling KH, Yeo PL, Spathopoulou A, Drake D, Choi J, Aron L, Garcia-Corral M, Ko T, Lee EA, Tam JM, Perlis RH, Church GM, Tsai LH, Yankner BA. Impaired neural stress resistance and loss of REST in bipolar disorder. Mol Psychiatry 2024; 29:153-164. [PMID: 37938767 DOI: 10.1038/s41380-023-02313-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 07/27/2023] [Accepted: 10/25/2023] [Indexed: 11/09/2023]
Abstract
Neurodevelopmental changes and impaired stress resistance have been implicated in the pathogenesis of bipolar disorder (BD), but the underlying regulatory mechanisms are unresolved. Here we describe a human cerebral organoid model of BD that exhibits altered neural development, elevated neural network activity, and a major shift in the transcriptome. These phenotypic changes were reproduced in cerebral organoids generated from iPS cell lines derived in different laboratories. The BD cerebral organoid transcriptome showed highly significant enrichment for gene targets of the transcriptional repressor REST. This was associated with reduced nuclear REST and REST binding to target gene recognition sites. Reducing the oxygen concentration in organoid cultures to a physiological range ameliorated the developmental phenotype and restored REST expression. These effects were mimicked by treatment with lithium. Reduced nuclear REST and derepression of REST targets genes were also observed in the prefrontal cortex of BD patients. Thus, an impaired cellular stress response in BD cerebral organoids leads to altered neural development and transcriptional dysregulation associated with downregulation of REST. These findings provide a new model and conceptual framework for exploring the molecular basis of BD.
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Affiliation(s)
- Katharina Meyer
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - King-Hwa Ling
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Pei-Ling Yeo
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | | | - Derek Drake
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Jaejoon Choi
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Liviu Aron
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Mariana Garcia-Corral
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
| | - Tak Ko
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Eunjung Alice Lee
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Jenny M Tam
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
| | - Roy H Perlis
- Center for Quantitative Health, Center for Genomic Medicine and Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA
| | - George M Church
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
| | - Li-Huei Tsai
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Bruce A Yankner
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA.
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4
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Steinert JR, Amal H. The contribution of an imbalanced redox signalling to neurological and neurodegenerative conditions. Free Radic Biol Med 2023; 194:71-83. [PMID: 36435368 DOI: 10.1016/j.freeradbiomed.2022.11.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/17/2022] [Accepted: 11/22/2022] [Indexed: 11/25/2022]
Abstract
Nitric oxide and other redox active molecules such as oxygen free radicals provide essential signalling in diverse neuronal functions, but their excess production and insufficient scavenging induces cytotoxic redox stress which is associated with numerous neurodegenerative and neurological conditions. A further component of redox signalling is mediated by a homeostatic regulation of divalent metal ions, the imbalance of which contributes to neuronal dysfunction. Additional antioxidant molecules such as glutathione and enzymes such as super oxide dismutase are involved in maintaining a physiological redox status within neurons. When cellular processes are perturbed and generation of free radicals overwhelms the antioxidants capacity of the neurons, a resulting redox damage leads to neuronal dysfunction and cell death. Cellular sources for production of redox-active molecules may include NADPH oxidases, mitochondria, cytochrome P450 and nitric oxide (NO)-generating enzymes, such as endothelial, neuronal and inducible NO synthases. Several neurodegenerative and developmental neurological conditions are associated with an imbalanced redox state as a result of neuroinflammatory processes leading to nitrosative and oxidative stress. Ongoing research aims at understanding the causes and consequences of such imbalanced redox homeostasis and its role in neuronal dysfunction.
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Affiliation(s)
- Joern R Steinert
- Division of Physiology, Pharmacology and Neuroscience, University of Nottingham, School of Life Sciences, Nottingham, NG7 2NR, UK.
| | - Haitham Amal
- Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel.
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5
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Abe K, Li J, Liu YY, Brent GA. Thyroid Hormone-mediated Histone Modification Protects Cortical Neurons From the Toxic Effects of Hypoxic Injury. J Endocr Soc 2022; 6:bvac139. [PMID: 36817622 PMCID: PMC9562813 DOI: 10.1210/jendso/bvac139] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Indexed: 11/19/2022] Open
Abstract
Context Thyroid hormone has been shown to have a protective role in neuronal injury, although the mechanisms have not been established. The cellular response to stress that promotes adaptation and survival has been shown to involve epigenetic modifications. Objective We hypothesized that the neuroprotective role of thyroid hormone was associated with epigenetic modifications of histone proteins. We used hypoxic neurons as a model system for hypoxia-induced brain injury. Methods Mouse primary cortical neurons were exposed to 0.2% oxygen for 7 hours, with or without, treatment with triiodothyronine (T3). We analyzed the expression of histone-modifying enzymes by RNA-seq and the post-translationally modified histone 3 proteins by enzyme-linked immunosorbent assay (ELISA) and Western blot. Results We found that methylation of H3K27, associated with inactive promoters, was highly induced in hypoxic neurons, and this histone methylation was reduced by T3 treatment. H3K4 methylation is the hallmark of active promoters. The expression of 3 (Set1db, Kmta2c, and Kmt2e) out of 6 H3K4 methyltransferases was downregulated by hypoxia and expression was restored by T3 treatment. H3K4me3 protein, measured by ELISA, was increased 76% in T3-treated hypoxic neurons compared with the levels without T3 treatment. H3K56ac plays a critical role in transcription initiation and was markedly increased in T3-treated hypoxic neurons compared with those without T3 treatment, indicating stimulation of gene transcription. Additionally, T3 treatment restored hypoxia-induced downregulation of histone acetyltransferase, Kat6a, Kat6b, and Crebbp, which function as transcription factors. Conclusion These findings indicate that T3 treatment mitigates hypoxia-induced histone modifications and protects neurons from hypoxia-induced injury.
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Affiliation(s)
- Kiyomi Abe
- Division of Endocrinology, Diabetes and Metabolism, Departments of Medicine and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA,Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
| | - Jianrong Li
- Division of Endocrinology, Diabetes and Metabolism, Departments of Medicine and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA,Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
| | - Yan Yun Liu
- Correspondence: Yan-Yun Liu, PhD, Division of Endocrinology, Diabetes and Metabolism, Departments of Medicine and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA; Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA. ; or Gregory A. Brent, MD, Division of Endocrinology, Diabetes and Metabolism, Departments of Medicine and Physiology, David Geffen School of Medicine at UCLA, and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA.
| | - Gregory A Brent
- Correspondence: Yan-Yun Liu, PhD, Division of Endocrinology, Diabetes and Metabolism, Departments of Medicine and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA; Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA. ; or Gregory A. Brent, MD, Division of Endocrinology, Diabetes and Metabolism, Departments of Medicine and Physiology, David Geffen School of Medicine at UCLA, and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA.
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6
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Kajtez J, Wesseler MF, Birtele M, Khorasgani FR, Rylander Ottosson D, Heiskanen A, Kamperman T, Leijten J, Martínez‐Serrano A, Larsen NB, Angelini TE, Parmar M, Lind JU, Emnéus J. Embedded 3D Printing in Self-Healing Annealable Composites for Precise Patterning of Functionally Mature Human Neural Constructs. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2201392. [PMID: 35712780 PMCID: PMC9443452 DOI: 10.1002/advs.202201392] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 05/14/2022] [Indexed: 05/02/2023]
Abstract
Human in vitro models of neural tissue with tunable microenvironment and defined spatial arrangement are needed to facilitate studies of brain development and disease. Towards this end, embedded printing inside granular gels holds great promise as it allows precise patterning of extremely soft tissue constructs. However, granular printing support formulations are restricted to only a handful of materials. Therefore, there has been a need for novel materials that take advantage of versatile biomimicry of bulk hydrogels while providing high-fidelity support for embedded printing akin to granular gels. To address this need, Authors present a modular platform for bioengineering of neuronal networks via direct embedded 3D printing of human stem cells inside Self-Healing Annealable Particle-Extracellular matrix (SHAPE) composites. SHAPE composites consist of soft microgels immersed in viscous extracellular-matrix solution to enable precise and programmable patterning of human stem cells and consequent generation mature subtype-specific neurons that extend projections into the volume of the annealed support. The developed approach further allows multi-ink deposition, live spatial and temporal monitoring of oxygen levels, as well as creation of vascular-like channels. Due to its modularity and versatility, SHAPE biomanufacturing toolbox has potential to be used in applications beyond functional modeling of mechanically sensitive neural constructs.
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Affiliation(s)
- Janko Kajtez
- Department of Experimental Medical SciencesWallenberg Neuroscience CenterDivision of Neurobiology and Lund Stem Cell CenterLund UniversityLundS‐221 84Sweden
- Department of Biotechnology and Biomedicine (DTU Bioengineering)Technical University of DenmarkKongens Lyngby2800Denmark
| | - Milan Finn Wesseler
- Department of Health Technology (DTU Health Tech)Technical University of DenmarkKongens Lyngby2800Denmark
| | - Marcella Birtele
- Department of Experimental Medical SciencesWallenberg Neuroscience CenterDivision of Neurobiology and Lund Stem Cell CenterLund UniversityLundS‐221 84Sweden
| | - Farinaz Riyahi Khorasgani
- Department of Biotechnology and Biomedicine (DTU Bioengineering)Technical University of DenmarkKongens Lyngby2800Denmark
| | - Daniella Rylander Ottosson
- Department of Experimental Medical SciencesWallenberg Neuroscience CenterDivision of Neurobiology and Lund Stem Cell CenterLund UniversityLundS‐221 84Sweden
| | - Arto Heiskanen
- Department of Biotechnology and Biomedicine (DTU Bioengineering)Technical University of DenmarkKongens Lyngby2800Denmark
| | - Tom Kamperman
- Department of Developmental BioEngineeringFaculty of Science and TechnologyTechnical Medical CentreUniversity of TwenteEnschede7522The Netherlands
| | - Jeroen Leijten
- Department of Developmental BioEngineeringFaculty of Science and TechnologyTechnical Medical CentreUniversity of TwenteEnschede7522The Netherlands
| | - Alberto Martínez‐Serrano
- Department of Molecular BiologyUniversidad Autónoma de Madridand Division of HomeostasisCenter of Molecular Biology Severo Ochoa (UAM‐CSIC)Madrid28049Spain
| | - Niels B. Larsen
- Department of Health Technology (DTU Health Tech)Technical University of DenmarkKongens Lyngby2800Denmark
| | - Thomas E. Angelini
- Department of Mechanical and Aerospace EngineeringUniversity of FloridaGainsvilleFL32611USA
| | - Malin Parmar
- Department of Experimental Medical SciencesWallenberg Neuroscience CenterDivision of Neurobiology and Lund Stem Cell CenterLund UniversityLundS‐221 84Sweden
| | - Johan U. Lind
- Department of Health Technology (DTU Health Tech)Technical University of DenmarkKongens Lyngby2800Denmark
| | - Jenny Emnéus
- Department of Biotechnology and Biomedicine (DTU Bioengineering)Technical University of DenmarkKongens Lyngby2800Denmark
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7
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Glutamate Uptake Is Not Impaired by Hypoxia in a Culture Model of Human Fetal Neural Stem Cell-Derived Astrocytes. Genes (Basel) 2022; 13:genes13030506. [PMID: 35328060 PMCID: PMC8953426 DOI: 10.3390/genes13030506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 03/04/2022] [Accepted: 03/09/2022] [Indexed: 02/04/2023] Open
Abstract
Hypoxic ischemic injury to the fetal and neonatal brain is a leading cause of death and disability worldwide. Although animal and culture studies suggest that glutamate excitotoxicity is a primary contributor to neuronal death following hypoxia, the molecular mechanisms, and roles of various neural cells in the development of glutamate excitotoxicity in humans, is not fully understood. In this study, we developed a culture model of human fetal neural stem cell (FNSC)-derived astrocytes and examined their glutamate uptake in response to hypoxia. We isolated, established, and characterized cultures of FNSCs from aborted fetal brains and differentiated them into astrocytes, characterized by increased expression of the astrocyte markers glial fibrillary acidic protein (GFAP), excitatory amino acid transporter 1 (EAAT1) and EAAT2, and decreased expression of neural stem cell marker Nestin. Differentiated astrocytes were exposed to various oxygen concentrations mimicking normoxia (20% and 6%), moderate and severe hypoxia (2% and 0.2%, respectively). Interestingly, no change was observed in the expression of the glutamate transporter EAAT2 or glutamate uptake by astrocytes, even after exposure to severe hypoxia for 48 h. These results together suggest that human FNSC-derived astrocytes can maintain glutamate uptake after hypoxic injury and thus provide evidence for the possible neuroprotective role of astrocytes in hypoxic conditions.
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8
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Haditsch U, Roth T, Rodriguez L, Hancock S, Cecere T, Nguyen M, Arastu-Kapur S, Broce S, Raha D, Lynch CC, Holsinger LJ, Dominy SS, Ermini F. Alzheimer's Disease-Like Neurodegeneration in Porphyromonas gingivalis Infected Neurons with Persistent Expression of Active Gingipains. J Alzheimers Dis 2021; 75:1361-1376. [PMID: 32390638 PMCID: PMC7369049 DOI: 10.3233/jad-200393] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Porphyromonas gingivalis (P. gingivalis) and its gingipain virulence factors have been identified as pathogenic effectors in Alzheimer's disease (AD). In a recent study we demonstrated the presence of gingipains in over 90% of postmortem AD brains, with gingipains localizing to the cytoplasm of neurons. However, infection of neurons by P. gingivalis has not been previously reported. OBJECTIVE To demonstrate intraneuronal P. gingivalis and gingipain expression in vitro after infecting neurons derived from human inducible pluripotent stem cells (iPSC) with P. gingivalis for 24, 48, and 72 h. METHODS Infection was characterized by transmission electron microscopy, confocal microscopy, and bacterial colony forming unit assays. Gingipain expression was monitored by immunofluorescence and RT-qPCR, and protease activity monitored with activity-based probes. Neurodegenerative endpoints were assessed by immunofluorescence, western blot, and ELISA. RESULTS Neurons survived the initial infection and showed time dependent, infection induced cell death. P. gingivalis was found free in the cytoplasm or in lysosomes. Infected neurons displayed an accumulation of autophagic vacuoles and multivesicular bodies. Tau protein was strongly degraded, and phosphorylation increased at T231. Over time, the density of presynaptic boutons was decreased. CONCLUSION P. gingivalis can invade and persist in mature neurons. Infected neurons display signs of AD-like neuropathology including the accumulation of autophagic vacuoles and multivesicular bodies, cytoskeleton disruption, an increase in phospho-tau/tau ratio, and synapse loss. Infection of iPSC-derived mature neurons by P. gingivalis provides a novel model system to study the cellular mechanisms leading to AD and to investigate the potential of new therapeutic approaches.
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Affiliation(s)
| | | | | | - Sandy Hancock
- Laboratory for Neurotoxicity Studies, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Thomas Cecere
- Laboratory for Neurotoxicity Studies, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Mai Nguyen
- Cortexyme, Inc., South San Francisco, CA, USA
| | | | - Sean Broce
- Cortexyme, Inc., South San Francisco, CA, USA
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9
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Ren C, Han R, Hu J, Li H, Li S, Liu Y, Cheng Z, Ji X, Ding Y. Hypoxia post-conditioning promoted glycolysis in mice cerebral ischemic model. Brain Res 2020; 1748:147044. [DOI: 10.1016/j.brainres.2020.147044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 07/30/2020] [Accepted: 07/31/2020] [Indexed: 01/10/2023]
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10
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Keeley TP, Mann GE. Defining Physiological Normoxia for Improved Translation of Cell Physiology to Animal Models and Humans. Physiol Rev 2019; 99:161-234. [PMID: 30354965 DOI: 10.1152/physrev.00041.2017] [Citation(s) in RCA: 179] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The extensive oxygen gradient between the air we breathe (Po2 ~21 kPa) and its ultimate distribution within mitochondria (as low as ~0.5-1 kPa) is testament to the efforts expended in limiting its inherent toxicity. It has long been recognized that cell culture undertaken under room air conditions falls short of replicating this protection in vitro. Despite this, difficulty in accurately determining the appropriate O2 levels in which to culture cells, coupled with a lack of the technology to replicate and maintain a physiological O2 environment in vitro, has hindered addressing this issue thus far. In this review, we aim to address the current understanding of tissue Po2 distribution in vivo and summarize the attempts made to replicate these conditions in vitro. The state-of-the-art techniques employed to accurately determine O2 levels, as well as the issues associated with reproducing physiological O2 levels in vitro, are also critically reviewed. We aim to provide the framework for researchers to undertake cell culture under O2 levels relevant to specific tissues and organs. We envisage that this review will facilitate a paradigm shift, enabling translation of findings under physiological conditions in vitro to disease pathology and the design of novel therapeutics.
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Affiliation(s)
- Thomas P Keeley
- King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London , London , United Kingdom
| | - Giovanni E Mann
- King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London , London , United Kingdom
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11
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Jiang S, Li T, Ji T, Yi W, Yang Z, Wang S, Yang Y, Gu C. AMPK: Potential Therapeutic Target for Ischemic Stroke. Am J Cancer Res 2018; 8:4535-4551. [PMID: 30214637 PMCID: PMC6134933 DOI: 10.7150/thno.25674] [Citation(s) in RCA: 160] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 07/16/2018] [Indexed: 02/07/2023] Open
Abstract
5'-AMP-activated protein kinase (AMPK), a member of the serine/threonine (Ser/Thr) kinase group, is universally distributed in various cells and organs. It is a significant endogenous defensive molecule that responds to harmful stimuli, such as cerebral ischemia, cerebral hemorrhage, and, neurodegenerative diseases (NDD). Cerebral ischemia, which results from insufficient blood flow or the blockage of blood vessels, is a major cause of ischemic stroke. Ischemic stroke has received increased attention due to its '3H' effects, namely high mortality, high morbidity, and high disability. Numerous studies have revealed that activation of AMPK plays a protective role in the brain, whereas its action in ischemic stroke remains elusive and poorly understood. Based on existing evidence, we introduce the basic structure, upstream regulators, and biological roles of AMPK. Second, we analyze the relationship between AMPK and the neurovascular unit (NVU). Third, the actions of AMPK in different phases of ischemia and current therapeutic methods are discussed. Finally, we evaluate existing controversy and provide a detailed analysis, followed by ethical issues, potential directions, and further prospects of AMPK. The information complied here may aid in clinical and basic research of AMPK, which may be a potent drug candidate for ischemic stroke treatment in the future.
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12
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Jaber SM, Bordt EA, Bhatt NM, Lewis DM, Gerecht S, Fiskum G, Polster BM. Sex differences in the mitochondrial bioenergetics of astrocytes but not microglia at a physiologically relevant brain oxygen tension. Neurochem Int 2018; 117:82-90. [PMID: 28888963 PMCID: PMC5839942 DOI: 10.1016/j.neuint.2017.09.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 08/14/2017] [Accepted: 09/05/2017] [Indexed: 11/22/2022]
Abstract
Biological sex is thought to influence mitochondrial bioenergetic function. Previous respiration measurements examining brain mitochondrial sex differences were made at atmospheric oxygen using isolated brain mitochondria. Oxygen is 160 mm Hg (21%) in the atmosphere, while the oxygen tension in the brain generally ranges from ∼5 to 45 mm Hg (∼1-6% O2). This study tested the hypothesis that sex and/or brain physiological oxygen tension influence the mitochondrial bioenergetic properties of primary rat cortical astrocytes and microglia. Oxygen consumption was measured with a Seahorse XF24 cell respirometer in an oxygen-controlled environmental chamber. Strikingly, male astrocytes had a higher maximal respiration than female astrocytes when cultured and assayed at 3% O2. Three percent O2 yielded a low physiological dissolved O2 level of ∼1.2% (9.1 mm Hg) at the cell monolayer during culture and 1.2-3.0% O2 during assays. No differences in bioenergetic parameters were observed between male and female astrocytes at 21% O2 (dissolved O2 of ∼19.7%, 150 mm Hg during culture) or between either of these cell populations and female astrocytes at 3% O2. In contrast to astrocytes, microglia showed no sex differences in mitochondrial bioenergetic parameters at either oxygen level, regardless of whether they were non-stimulated or activated to a proinflammatory state. There were also no O2- or sex-dependent differences in proinflammatory TNF-α or IL-1β cytokine secretion measured at 18 h activation. Overall, results reveal an intriguing sex variance in astrocytic maximal respiration that requires additional investigation. Findings also demonstrate that sex differences can be masked by conducting experiments at non-physiological O2.
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Affiliation(s)
- Sausan M Jaber
- Department of Anesthesiology, and the Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, 685 W. Baltimore ST., MSTF 5-34, Baltimore, MD, 21201, USA; Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 685 W. Baltimore ST., MSTF 5-34, Baltimore, MD, 21201, USA
| | - Evan A Bordt
- Department of Anesthesiology, and the Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, 685 W. Baltimore ST., MSTF 5-34, Baltimore, MD, 21201, USA
| | - Niraj M Bhatt
- Department of Anesthesiology, and the Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, 685 W. Baltimore ST., MSTF 5-34, Baltimore, MD, 21201, USA
| | - Daniel M Lewis
- Department of Chemical and Biomolecular Engineering, Institute for NanoBioTechnology, Johns Hopkins University, 3400 North Charles Street, Shaffer Hall 200C, Baltimore, MD 21218, USA
| | - Sharon Gerecht
- Department of Chemical and Biomolecular Engineering, Institute for NanoBioTechnology, Johns Hopkins University, 3400 North Charles Street, Shaffer Hall 200C, Baltimore, MD 21218, USA; Department of Materials Science and Engineering, Johns Hopkins University, 3400 North Charles Street, Shaffer Hall 200C, Baltimore, MD 21218, USA
| | - Gary Fiskum
- Department of Anesthesiology, and the Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, 685 W. Baltimore ST., MSTF 5-34, Baltimore, MD, 21201, USA; Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 685 W. Baltimore ST., MSTF 5-34, Baltimore, MD, 21201, USA
| | - Brian M Polster
- Department of Anesthesiology, and the Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, 685 W. Baltimore ST., MSTF 5-34, Baltimore, MD, 21201, USA; Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 685 W. Baltimore ST., MSTF 5-34, Baltimore, MD, 21201, USA.
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13
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An P, Wu T, Yu H, Fang K, Ren Z, Tang M. Hispidulin Protects Against Focal Cerebral Ischemia Reperfusion Injury in Rats. J Mol Neurosci 2018; 65:203-212. [PMID: 29799104 DOI: 10.1007/s12031-018-1086-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 05/11/2018] [Indexed: 02/02/2023]
Abstract
Focal cerebral ischemia is associated with ischemia/reperfusion (I/R) injury. Hispidulin is a flavonoid compound with a variety of pharmacological properties. The neuroprotective effects of hispidulin have not been fully elucidated. Herein, we demonstrated that pretreatment of animals with hispidulin improved the neurological outcomes and decreased the infarct size and brain edema in the cerebral focal I/R model. Mechanistically, we showed in vivo and in vitro that hispidulin exerted a protective effect against I/R injury by inducing the Nrf2 antioxidant pathway through modulation of AMPK/GSK3β signaling. Taken together, our results suggest that hispidulin may be a useful neuroprotective agent against ischemia/reperfusion (I/R) injury.
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Affiliation(s)
- Pengpeng An
- The Affiliated Qingdao Hiser Hospital of Qingdao University (Qingdao Hospital of Traditional Chinese Medicine), Renming Road 4, Qingdao, 266000, China
| | - Tianhui Wu
- Qingdao Fifth People's Hospital (Shandong Qingdao Hospital of Integrated Traditional and Western Medicine), Qingdao, China
| | - Huanqing Yu
- Qingdao Fifth People's Hospital (Shandong Qingdao Hospital of Integrated Traditional and Western Medicine), Qingdao, China
| | - Kun Fang
- Qingdao Fifth People's Hospital (Shandong Qingdao Hospital of Integrated Traditional and Western Medicine), Qingdao, China
| | - Zhizhen Ren
- Community Health Service Center of Shinan District, Qingdao, China
| | - Ming Tang
- The Affiliated Qingdao Hiser Hospital of Qingdao University (Qingdao Hospital of Traditional Chinese Medicine), Renming Road 4, Qingdao, 266000, China.
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14
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Keeley TP, Siow RCM, Jacob R, Mann GE. Reduced SERCA activity underlies dysregulation of Ca 2+ homeostasis under atmospheric O 2 levels. FASEB J 2017; 32:2531-2538. [PMID: 29273673 PMCID: PMC5901376 DOI: 10.1096/fj.201700685rrr] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Unregulated increases in cellular Ca2+ homeostasis are a hallmark of pathophysiological conditions and a key trigger of cell death. Endothelial cells cultured under physiologic O2 conditions (5% O2) exhibit a reduced cytosolic Ca2+ response to stimulation. The mechanism for reduced plateau [Ca2+]i upon stimulation was due to increased sarco/endoplasmic reticulum Ca2+ ATPase (SERCA)-mediated reuptake rather than changes in Ca2+ influx capacity. Agonist-stimulated phosphorylation of the SERCA regulatory protein phospholamban was increased in cells cultured under 5% O2. Elevation of cytosolic and mitochondrial [Ca2+] and cell death after prolonged ionomycin treatment, as a model of Ca2+ overload, were lower when cells were cultured long-term under 5% compared with 18% O2. This protection was abolished by cotreatment with the SERCA inhibitor cyclopiazonic acid. Taken together, these results demonstrate that culturing cells under hyperoxic conditions reduces their ability to efficiently regulate [Ca2+]i, resulting in greater sensitivity to cytotoxic stimuli.-Keeley, T. P., Siow, R. C. M., Jacob, R., Mann, G. E. Reduced SERCA activity underlies dysregulation of Ca2+ homeostasis under atmospheric O2 levels.
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Affiliation(s)
- Thomas P Keeley
- King's British Heart Foundation Centre for Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Richard C M Siow
- King's British Heart Foundation Centre for Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Ron Jacob
- King's British Heart Foundation Centre for Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Giovanni E Mann
- King's British Heart Foundation Centre for Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
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15
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Guidelines on experimental methods to assess mitochondrial dysfunction in cellular models of neurodegenerative diseases. Cell Death Differ 2017; 25:542-572. [PMID: 29229998 PMCID: PMC5864235 DOI: 10.1038/s41418-017-0020-4] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/06/2017] [Accepted: 10/12/2017] [Indexed: 01/22/2023] Open
Abstract
Neurodegenerative diseases are a spectrum of chronic, debilitating disorders characterised by the progressive degeneration and death of neurons. Mitochondrial dysfunction has been implicated in most neurodegenerative diseases, but in many instances it is unclear whether such dysfunction is a cause or an effect of the underlying pathology, and whether it represents a viable therapeutic target. It is therefore imperative to utilise and optimise cellular models and experimental techniques appropriate to determine the contribution of mitochondrial dysfunction to neurodegenerative disease phenotypes. In this consensus article, we collate details on and discuss pitfalls of existing experimental approaches to assess mitochondrial function in in vitro cellular models of neurodegenerative diseases, including specific protocols for the measurement of oxygen consumption rate in primary neuron cultures, and single-neuron, time-lapse fluorescence imaging of the mitochondrial membrane potential and mitochondrial NAD(P)H. As part of the Cellular Bioenergetics of Neurodegenerative Diseases (CeBioND) consortium (www.cebiond.org), we are performing cross-disease analyses to identify common and distinct molecular mechanisms involved in mitochondrial bioenergetic dysfunction in cellular models of Alzheimer’s, Parkinson’s, and Huntington’s diseases. Here we provide detailed guidelines and protocols as standardised across the five collaborating laboratories of the CeBioND consortium, with additional contributions from other experts in the field.
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16
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Hall ME, Mohtaram NK, Willerth SM, Edwards R. Modeling the behavior of human induced pluripotent stem cells seeded on melt electrospun scaffolds. J Biol Eng 2017; 11:38. [PMID: 29075321 PMCID: PMC5651653 DOI: 10.1186/s13036-017-0080-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 09/20/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Human induced pluripotent stem cells (hiPSCs) can form any tissue found in the body, making them attractive for regenerative medicine applications. Seeding hiPSC aggregates into biomaterial scaffolds can control their differentiation into specific tissue types. Here we develop and analyze a mathematical model of hiPSC aggregate behavior when seeded on melt electrospun scaffolds with defined topography. RESULTS We used ordinary differential equations to model the different cellular populations (stem, progenitor, differentiated) present in our scaffolds based on experimental results and published literature. Our model successfully captures qualitative features of the cellular dynamics observed experimentally. We determined the optimal parameter sets to maximize specific cellular populations experimentally, showing that a physiologic oxygen level (∼ 5%) increases the number of neural progenitors and differentiated neurons compared to atmospheric oxygen levels (∼ 21%) and a scaffold porosity of ∼ 63% maximizes aggregate size. CONCLUSIONS Our mathematical model determined the key factors controlling hiPSC behavior on melt electrospun scaffolds, enabling optimization of experimental parameters.
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Affiliation(s)
- Meghan E. Hall
- Department of Mathematics and Statistics, University of Victoria, Victoria, Canada
| | | | - Stephanie M. Willerth
- Department of Mechanical Engineering, University of Victoria, Victoria, Canada
- Division of Medical Sciences, University of Victoria, Victoria, Canada
- Department of Biochemistry, University of British Columbia, Vancouver, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, Canada
- Centre for Biomedical Research, University of Victoria, Victoria, Canada
| | - Roderick Edwards
- Department of Mathematics and Statistics, University of Victoria, Victoria, Canada
- Centre for Biomedical Research, University of Victoria, Victoria, Canada
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17
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Džinić T, Hartwig S, Lehr S, Dencher NA. Oxygen and differentiation status modulate the effect of X-ray irradiation on physiology and mitochondrial proteome of human neuroblastoma cells. Arch Physiol Biochem 2016; 122:257-265. [PMID: 27615280 DOI: 10.1080/13813455.2016.1218518] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cytotoxic effects, including oxidative stress, of low linear energy transfer (LET)-ionizing radiation are often underestimated and studies of their mechanisms using cell culture models are widely conducted with cells cultivated at atmospheric oxygen that does not match its physiological levels in body tissues. Also, cell differentiation status plays a role in the outcome of experiments. We compared effects of 2 Gy X-ray irradiation on the physiology and mitochondrial proteome of nondifferentiated and human neuroblastoma (SH-SY5Y) cells treated with retinoic acid cultivated at 21% and 5% O2. Irradiation did not affect the amount of subunits of OxPhos complexes and other non-OxPhos mitochondrial proteins, except for heat shock protein 70, which was increased depending on oxygen level and differentiation status. These two factors were proven to modulate mitochondrial membrane potential and the bioenergetic status of cells. We suggest, moreover, that oxygen plays a role in the differentiation of human SH-SY5Y cells.
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Affiliation(s)
- Tamara Džinić
- a Physical Biochemistry, Department of Chemistry , Technische Universität Darmstadt , Darmstadt , Germany
| | - Sonja Hartwig
- b Institute of Clinical Biochemistry and Pathobiochemistry, German Diabetes Center at the Heinrich-Heine-University Düsseldorf, Leibniz Center for Diabetes Research , Düsseldorf , Germany , and
- c German Center for Diabetes Research (DZD) , München , Neuherberg , Germany
| | - Stefan Lehr
- b Institute of Clinical Biochemistry and Pathobiochemistry, German Diabetes Center at the Heinrich-Heine-University Düsseldorf, Leibniz Center for Diabetes Research , Düsseldorf , Germany , and
- c German Center for Diabetes Research (DZD) , München , Neuherberg , Germany
| | - Norbert A Dencher
- a Physical Biochemistry, Department of Chemistry , Technische Universität Darmstadt , Darmstadt , Germany
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18
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Eom JW, Lee JM, Koh JY, Kim YH. AMP-activated protein kinase contributes to zinc-induced neuronal death via activation by LKB1 and induction of Bim in mouse cortical cultures. Mol Brain 2016; 9:14. [PMID: 26856538 PMCID: PMC4746814 DOI: 10.1186/s13041-016-0194-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 02/01/2016] [Indexed: 12/25/2022] Open
Abstract
Background We reported that zinc neurotoxicity, a key mechanism of ischemic neuronal death, was mediated by poly ADP-ribose polymerase (PARP) over-activation following NAD+/ATP depletion in cortical cultures. Because AMP-activated protein kinase (AMPK) can be activated by ATP depletion, and AMPK plays a key role in excitotoxicity and ischemic neuronal death, we examined whether AMPK could be involved in zinc neurotoxicity in mouse cortical neuronal cultures. Results Compound C, an AMPK inhibitor, significantly attenuated zinc-induced neuronal death. Activation of AMPK was detected beginning 2 h after a 10-min exposure of mouse cortical neurons to 300 μM zinc, although a significant change in AMP level was not detected until 4 h after zinc treatment. Thus, AMPK activation might not have been induced by an increase in intracellular AMP in zinc neurotoxicity. Furthermore, we observed that liver kinase B1 (LKB1) but not Ca2+/calmodulin-dependent protein kinase kinase β (CaMKKβ), was involved in AMPK activation. Although STO-609, a chemical inhibitor of CaMKKβ, significantly attenuated zinc neurotoxicity, zinc-induced AMPK activation was not affected, which suggested that CaMKKβ was not involved in AMPK activation. Knockdown of LKB1 by siRNA significantly reduced zinc neurotoxicity, as well as zinc-induced AMPK activation, which indicated a possible role for LKB1 as an upstream kinase for AMPK activation. In addition, mRNA and protein levels of Bim, a pro-apoptotic Bcl-2 family member, were noticeably increased by zinc in an AMPK-dependent manner. Finally, caspase-3 activation in zinc-induced neuronal death was mediated by LKB1 and AMPK activation. Conclusions The results suggested that AMPK mediated zinc-induced neuronal death via up-regulation of Bim and activation of caspase-3. Rapid activation of AMPK was detected after exposure of cortical neuronal cultures to zinc, which was induced by LKB1 activation but not increased intracellular AMP levels or CaMKKβ activation. Hence, blockade of AMPK in the brain may protect against zinc neurotoxicity, which is likely to occur after acute brain injury.
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Affiliation(s)
- Jae-Won Eom
- Department of Molecular Biology, Sejong University, Seoul, 143-747, South Korea.
| | - Jong-Min Lee
- Department of Molecular Biology, Sejong University, Seoul, 143-747, South Korea. .,Department of Integrative Bioscience and Biotechnology, Sejong University, Seoul, 143-747, South Korea.
| | - Jae-Young Koh
- Neural Injury Research Lab & Department of Neurology, University of Ulsan College of Medicine, Seoul, 138-736, South Korea.
| | - Yang-Hee Kim
- Department of Molecular Biology, Sejong University, Seoul, 143-747, South Korea. .,Department of Integrative Bioscience and Biotechnology, Sejong University, Seoul, 143-747, South Korea.
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19
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Kagawa Y, Matsuura K, Shimizu T, Tsuneda S. Direct measurement of local dissolved oxygen concentration spatial profiles in a cell culture environment. Biotechnol Bioeng 2015; 112:1263-74. [PMID: 25565074 DOI: 10.1002/bit.25531] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 12/18/2014] [Accepted: 12/23/2014] [Indexed: 02/02/2023]
Abstract
Controlling local dissolved oxygen concentration (DO) in media is critical for cell or tissue cultures. Various biomaterials and culture methods have been developed to modulate DO. Direct measurement of local DO in cultures has not been validated as a method to test DO modulation. In the present study we developed a DO measurement system equipped with a Clark-type oxygen microelectrode manipulated with 1 μm precision in three-dimensional space to explore potential applications for tissue engineering. By determining the microelectrode tip position precisely against the bottom plane of culture dishes with rat or human cardiac cells in static monolayer culture, we successfully obtained spatial distributions of DO in the medium. Theoretical quantitative predictions fit the obtained data well. Based on analyses of the variance between samples, we found the data reflected "local" oxygen consumption in the vicinity of the microelectrode and the detection of temporal changes in oxygen consumption rates of cultured cells was limited by the diffusion rate of oxygen in the medium. This oxygen measuring system monitors local oxygen consumption and production with high spatial resolution, and can potentially be used with recently developed oxygen modulating biomaterials to design microenvironments and non-invasively monitor local DO dynamics during culture.
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Affiliation(s)
- Yuki Kagawa
- Institute for Nanoscience and Nanotechnology, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo 162-8480, Japan
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20
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McFadden JW, Aja S, Li Q, Bandaru VVR, Kim EK, Haughey NJ, Kuhajda FP, Ronnett GV. Increasing fatty acid oxidation remodels the hypothalamic neurometabolome to mitigate stress and inflammation. PLoS One 2014; 9:e115642. [PMID: 25541737 PMCID: PMC4277346 DOI: 10.1371/journal.pone.0115642] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 11/25/2014] [Indexed: 11/18/2022] Open
Abstract
Modification of hypothalamic fatty acid (FA) metabolism can improve energy homeostasis and prevent hyperphagia and excessive weight gain in diet-induced obesity (DIO) from a diet high in saturated fatty acids. We have shown previously that C75, a stimulator of carnitine palmitoyl transferase-1 (CPT-1) and fatty acid oxidation (FAOx), exerts at least some of its hypophagic effects via neuronal mechanisms in the hypothalamus. In the present work, we characterized the effects of C75 and another anorexigenic compound, the glycerol-3-phosphate acyltransferase (GPAT) inhibitor FSG67, on FA metabolism, metabolomics profiles, and metabolic stress responses in cultured hypothalamic neurons and hypothalamic neuronal cell lines during lipid excess with palmitate. Both compounds enhanced palmitate oxidation, increased ATP, and inactivated AMP-activated protein kinase (AMPK) in hypothalamic neurons in vitro. Lipidomics and untargeted metabolomics revealed that enhanced catabolism of FA decreased palmitate availability and prevented the production of fatty acylglycerols, ceramides, and cholesterol esters, lipids that are associated with lipotoxicity-provoked metabolic stress. This improved metabolic signature was accompanied by increased levels of reactive oxygen species (ROS), and yet favorable changes in oxidative stress, overt ER stress, and inflammation. We propose that enhancing FAOx in hypothalamic neurons exposed to excess lipids promotes metabolic remodeling that reduces local inflammatory and cell stress responses. This shift would restore mitochondrial function such that increased FAOx can produce hypothalamic neuronal ATP and lead to decreased food intake and body weight to improve systemic metabolism.
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Affiliation(s)
- Joseph W. McFadden
- Center for Metabolism and Obesity Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Susan Aja
- Center for Metabolism and Obesity Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
| | - Qun Li
- Center for Metabolism and Obesity Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Veera V. R. Bandaru
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Eun-Kyoung Kim
- Department of Brain Science, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
| | - Norman J. Haughey
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Francis P. Kuhajda
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Gabriele V. Ronnett
- Center for Metabolism and Obesity Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Brain Science, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
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21
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Hughes SM, Hope KM, Xu JB, Mitchell NL, Palmer DN. Inhibition of storage pathology in prenatal CLN5-deficient sheep neural cultures by lentiviral gene therapy. Neurobiol Dis 2014; 62:543-50. [PMID: 24269732 DOI: 10.1016/j.nbd.2013.11.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 11/01/2013] [Accepted: 11/12/2013] [Indexed: 12/12/2022] Open
Abstract
The neuronal ceroid lipofuscinoses (NCLs, Batten disease) are inherited neurodegenerative lysosomal storage diseases caused by mutations in several different genes. Mutations in CLN5 cause a variant late-infantile human disease and some cases of juvenile and adult clinical disease. NCLs also occur in animals, and a flock of New Zealand Borderdale sheep with a CLN5 splice-site mutation has been developed for model studies. Dissociated mixed neural cells from CLN5-deficient foetal sheep brains contained no obvious storage bodies at plating but these accumulated rapidly in culture, mainly in microglial cells and also in neurons and astrocytes. Accumulation was very obvious after a week, as monitored by fluorescent microscopy and immunostaining for subunit c of mitochondrial ATP synthase. Photography at intervals revealed the dynamic nature of the cultures and a flow of storage bodies between cells, specifically the phagocytosis of storage-body containing cells by microglia and incorporation of the storage bodies into the host cells. No storage was observed in cultured control cells. Transduction of cell cultures with a lentiviral vector expressing a C-terminal Myc tagged CLN5 resulted in secretion of post-translationally glycosylated and processed CLN5. Transduction of CLN5-deficient cultures with this construct rapidly reversed storage body accumulation, to less than half in only six days. These results show that storage body accumulation is reversible with enzyme correction and support the use of these cultures for testing of therapeutics prior to whole animal studies.
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Affiliation(s)
- Stephanie M Hughes
- Department of Biochemistry, Otago School of Medical Sciences, University of Otago, PO Box 54, Dunedin 9054, New Zealand; Brain Health Research Centre, University of Otago, PO Box 54, Dunedin 9054, New Zealand.
| | - Katie M Hope
- Department of Biochemistry, Otago School of Medical Sciences, University of Otago, PO Box 54, Dunedin 9054, New Zealand.
| | - Janet Boyu Xu
- Faculty of Agriculture and Life Sciences, PO Box 85084, Lincoln University, Lincoln 7647, New Zealand.
| | - Nadia L Mitchell
- Faculty of Agriculture and Life Sciences, PO Box 85084, Lincoln University, Lincoln 7647, New Zealand.
| | - David N Palmer
- Faculty of Agriculture and Life Sciences, PO Box 85084, Lincoln University, Lincoln 7647, New Zealand.
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22
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Bilican B, Livesey MR, Haghi G, Qiu J, Burr K, Siller R, Hardingham GE, Wyllie DJA, Chandran S. Physiological normoxia and absence of EGF is required for the long-term propagation of anterior neural precursors from human pluripotent cells. PLoS One 2014; 9:e85932. [PMID: 24465796 PMCID: PMC3895023 DOI: 10.1371/journal.pone.0085932] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 12/03/2013] [Indexed: 12/23/2022] Open
Abstract
Widespread use of human pluripotent stem cells (hPSCs) to study neuronal physiology and function is hindered by the ongoing need for specialist expertise in converting hPSCs to neural precursor cells (NPCs). Here, we describe a new methodology to generate cryo-preservable hPSC-derived NPCs that retain an anterior identity and are propagatable long-term prior to terminal differentiation, thus abrogating regular de novo neuralization. Key to achieving passagable NPCs without loss of identity is the combination of both absence of EGF and propagation in physiological levels (3%) of O2. NPCs generated in this way display a stable long-term anterior forebrain identity and importantly retain developmental competence to patterning signals. Moreover, compared to NPCs maintained at ambient O2 (21%), they exhibit enhanced uniformity and speed of functional maturation, yielding both deep and upper layer cortical excitatory neurons. These neurons display multiple attributes including the capability to form functional synapses and undergo activity-dependent gene regulation. The platform described achieves long-term maintenance of anterior neural precursors that can give rise to forebrain neurones in abundance, enabling standardised functional studies of neural stem cell maintenance, lineage choice and neuronal functional maturation for neurodevelopmental research and disease-modelling.
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Affiliation(s)
- Bilada Bilican
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom
- MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, United Kingdom
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom
| | - Matthew R. Livesey
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Ghazal Haghi
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Jing Qiu
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Karen Burr
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom
- MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, United Kingdom
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom
| | - Rick Siller
- MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, United Kingdom
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom
| | - Giles E. Hardingham
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - David J. A. Wyllie
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail: (DJAW); (SC)
| | - Siddharthan Chandran
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, United Kingdom
- MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, United Kingdom
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail: (DJAW); (SC)
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23
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Byerly MS, Petersen PS, Ramamurthy S, Seldin MM, Lei X, Provost E, Wei Z, Ronnett GV, Wong GW. C1q/TNF-related protein 4 (CTRP4) is a unique secreted protein with two tandem C1q domains that functions in the hypothalamus to modulate food intake and body weight. J Biol Chem 2013; 289:4055-69. [PMID: 24366864 DOI: 10.1074/jbc.m113.506956] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
CTRP4 is a unique member of the C1q family, possessing two tandem globular C1q domains. Its physiological function is poorly defined. Here, we show that CTRP4 is an evolutionarily conserved, ∼34-kDa secretory protein expressed in the brain. In human, mouse, and zebrafish brain, CTRP4 expression begins early in development and is widespread in the central nervous system. Neurons, but not astrocytes, express and secrete CTRP4, and secreted proteins form higher-order oligomeric complexes. CTRP4 is also produced by peripheral tissues and circulates in blood. Its serum levels are increased in leptin-deficient obese (ob/ob) mice. Functional studies suggest that CTRP4 acts centrally to modulate energy metabolism. Refeeding following an overnight fast induced the expression of CTRP4 in the hypothalamus. Central administration of recombinant protein suppressed food intake and altered the whole-body energy balance in both chow-fed and high-fat diet-fed mice. Suppression of food intake by CTRP4 is correlated with a decreased expression of orexigenic neuropeptide (Npy and Agrp) genes in the hypothalamus. These results establish CTRP4 as a novel nutrient-responsive central regulator of food intake and energy balance.
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24
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Ramamurthy S, Chang E, Cao Y, Zhu J, Ronnett GV. AMPK activation regulates neuronal structure in developing hippocampal neurons. Neuroscience 2013; 259:13-24. [PMID: 24295634 DOI: 10.1016/j.neuroscience.2013.11.048] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 11/21/2013] [Accepted: 11/23/2013] [Indexed: 12/25/2022]
Abstract
AMP-activated protein kinase (AMPK) is a serine/threonine kinase that functions as a cellular and whole organism energy sensor to regulate ATP-consuming (anabolic) and ATP-generating (catabolic) pathways. The heterotrimeric AMPK complex consists of a catalytic α-subunit, regulatory β-subunit, and an AMP/ATP-binding γ-subunit. Several alternate isoforms exist for each subunit (α1, α2, β1, β2, γ1, γ2 and γ3). However, little is known of the expression pattern or function of the individual catalytic complexes in regulating neuronal structure. In this study, we examined the role of AMPK subunits in differentiating hippocampal neurons. We found that during development, the expression of AMPK subunits increase and that activation of AMPK by energetic stress inhibits neuronal development at multiple stages, not only during axon outgrowth, but also during dendrite growth and arborization. The presence of a single functional AMPK catalytic complex was sufficient to mediate these inhibitory effects of energetic stress. Activation of AMPK mediates these effects by suppressing both the mTOR and Akt signaling pathways. These findings demonstrate that the energy-sensing AMPK pathway regulates neuronal structure in distinct regions of developing neurons at multiple stages of development.
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Affiliation(s)
- S Ramamurthy
- Department of Neuroscience, Johns Hopkins University School of Medicine, 855 N Wolfe Street, Baltimore, MD 21205, USA; Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, 855 N Wolfe Street, Baltimore, MD 21205, USA
| | - E Chang
- Department of Neuroscience, Johns Hopkins University School of Medicine, 855 N Wolfe Street, Baltimore, MD 21205, USA; Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, 855 N Wolfe Street, Baltimore, MD 21205, USA
| | - Y Cao
- Department of Neuroscience, Johns Hopkins University School of Medicine, 855 N Wolfe Street, Baltimore, MD 21205, USA; Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, 855 N Wolfe Street, Baltimore, MD 21205, USA
| | - J Zhu
- Department of Neuroscience, Johns Hopkins University School of Medicine, 855 N Wolfe Street, Baltimore, MD 21205, USA; Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, 855 N Wolfe Street, Baltimore, MD 21205, USA
| | - G V Ronnett
- Department of Neuroscience, Johns Hopkins University School of Medicine, 855 N Wolfe Street, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, 855 N Wolfe Street, Baltimore, MD 21205, USA; Department of Biological Chemistry, Johns Hopkins University School of Medicine, 855 N Wolfe Street, Baltimore, MD 21205, USA; Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, 855 N Wolfe Street, Baltimore, MD 21205, USA; Daegu Gyeongbuk Institute of Science and Technology, Daegu, Republic of Korea.
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25
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Pathak D, Berthet A, Nakamura K. Energy failure: does it contribute to neurodegeneration? Ann Neurol 2013; 74:506-16. [PMID: 24038413 PMCID: PMC4092015 DOI: 10.1002/ana.24014] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 08/09/2013] [Accepted: 08/16/2013] [Indexed: 12/11/2022]
Abstract
Energy failure from mitochondrial dysfunction is proposed to be a central mechanism leading to neuronal death in a range of neurodegenerative diseases. However, energy failure has never been directly demonstrated in affected neurons in these diseases, nor has it been proved to produce degeneration in disease models. Therefore, despite considerable indirect evidence, it is not known whether energy failure truly occurs in susceptible neurons, and whether this failure is responsible for their death. This limited understanding results primarily from a lack of sensitivity and resolution of available tools and assays and the inherent limitations of in vitro model systems. Major advances in these methodologies and approaches should greatly enhance our understanding of the relationship between energy failure, neuronal dysfunction, and death, and help us to determine whether boosting bioenergetic function would be an effective therapeutic approach. Here we review the current evidence that energy failure occurs in and contributes to neurodegenerative disease, and consider new approaches that may allow us to better address this central issue.
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Affiliation(s)
- Divya Pathak
- Gladstone Institute of Neurological Disease, University of California, San Francisco, San Francisco, CA
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26
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Manwani B, McCullough LD. Function of the master energy regulator adenosine monophosphate-activated protein kinase in stroke. J Neurosci Res 2013; 91:1018-29. [PMID: 23463465 PMCID: PMC4266469 DOI: 10.1002/jnr.23207] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2012] [Revised: 12/24/2012] [Accepted: 01/05/2013] [Indexed: 01/09/2023]
Abstract
Adenosine monophosphate-activated protein kinase (AMPK) is an evolutionarily conserved signaling molecule that is emerging as one of the most important energy sensors in the body. AMPK monitors cellular energy status and is activated via phosphorylation when energy stores are low. This allows for maintenance of energy homeostasis by promoting catabolic pathways for ATP production and limiting processes that consume ATP. Growing number of stimuli have been shown to activate AMPK, and AMPK has been implicated in many diverse biological processes, including cell polarity, autophagy, and senescence. The effect of AMPK activation and its biological functions are extremely diverse and depend on both the overall energy "milieu" and the location and duration of activation. AMPK has tissue- and isoform-specific functions in the brain vs. periphery. These functions and the pathways activated also appear to differ by cell location (hypothalamus vs. cortex), cell type (astrocyte vs. neuron), and duration of exposure. Short bursts of AMPK activation have been found to be involved in ischemic preconditioning and neuronal survival; however, prolonged AMPK activity during ischemia leads to neuronal cell death. AMPK may also underlie some of the beneficial effects of hypothermia, a potential therapy for ischemic brain injury. This review discusses the role of AMPK in ischemic stroke, a condition of severe energy depletion.
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Affiliation(s)
- Bharti Manwani
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
| | - Louise D. McCullough
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
- Department of Neurology, University of Connecticut Health Center, Farmington, Connecticut
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27
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Ramamurthy S, Ronnett G. AMP-Activated Protein Kinase (AMPK) and Energy-Sensing in the Brain. Exp Neurobiol 2012; 21:52-60. [PMID: 22792025 PMCID: PMC3381212 DOI: 10.5607/en.2012.21.2.52] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Accepted: 02/09/2012] [Indexed: 12/25/2022] Open
Abstract
5'-adenosine monophosphate-activated protein kinase (AMPK) is an evolutionarily conserved cellular and organismal energy integrator that responds to numerous stimuli with the overall intention to facilitate energy conservation and enhance energy balance while also affecting cellular survival and behaviors. AMPK has been appreciated for many years to function in peripheral organs that contribute to the generation or disposition of cellular energy, while its role in the brain has been only recently elucidated. While acknowledged to respond to organismal energy balance, we now recognize that energy balance within neurons also affects the brain's response to these peripheral signals. In this review, we discuss AMPK's regulation and its ever-expanding role as a neuronal energy integrator at both the cellular and systems levels.
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Affiliation(s)
- Santosh Ramamurthy
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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