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Ryan F, Khoshnam SE, Khodagholi F, Ashabi G, Ahmadiani A. How cytosolic compartments play safeguard functions against neuroinflammation and cell death in cerebral ischemia. Metab Brain Dis 2021; 36:1445-1467. [PMID: 34173922 DOI: 10.1007/s11011-021-00770-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Accepted: 06/06/2021] [Indexed: 11/26/2022]
Abstract
Ischemic stroke is the second leading cause of mortality and disability globally. Neuronal damage following ischemic stroke is rapid and irreversible, and eventually results in neuronal death. In addition to activation of cell death signaling, neuroinflammation is also considered as another pathogenesis that can occur within hours after cerebral ischemia. Under physiological conditions, subcellular organelles play a substantial role in neuronal functionality and viability. However, their functions can be remarkably perturbed under neurological disorders, particularly cerebral ischemia. Therefore, their biochemical and structural response has a determining role in the sequel of neuronal cells and the progression of disease. However, their effects on cell death and neuroinflammation, as major underlying mechanisms of ischemic stroke, are still not understood. This review aims to provide a comprehensive overview of the contribution of each organelle on these pathological processes after ischemic stroke.
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Affiliation(s)
- Fari Ryan
- Centre for Research in Neuroscience, The Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Seyed Esmaeil Khoshnam
- Persian Gulf Physiology Research Centre, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Fariba Khodagholi
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ghorbangol Ashabi
- Department of Physiology, Faculty of Medicine, Tehran University of Medical Sciences, PO Box: 1417613151, Tehran, Iran.
| | - Abolhassan Ahmadiani
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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2
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Han Y, Yuan M, Guo YS, Shen XY, Gao ZK, Bi X. Mechanism of Endoplasmic Reticulum Stress in Cerebral Ischemia. Front Cell Neurosci 2021; 15:704334. [PMID: 34408630 PMCID: PMC8365026 DOI: 10.3389/fncel.2021.704334] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 07/09/2021] [Indexed: 12/25/2022] Open
Abstract
Endoplasmic reticulum (ER) is the main organelle for protein synthesis, trafficking and maintaining intracellular Ca2+ homeostasis. The stress response of ER results from the disruption of ER homeostasis in neurological disorders. Among these disorders, cerebral ischemia is a prevalent reason of death and disability in the world. ER stress stemed from ischemic injury initiates unfolded protein response (UPR) regarded as a protection mechanism. Important, disruption of Ca2+ homeostasis resulted from cytosolic Ca2+ overload and depletion of Ca2+ in the lumen of the ER could be a trigger of ER stress and the misfolded protein synthesis. Brain cells including neurons, glial cells and endothelial cells are involved in the complex pathophysiology of ischemic stroke. This is generally important for protein underfolding, but even more for cytosolic Ca2+ overload. Mild ER stress promotes cells to break away from danger signals and enter the adaptive procedure with the activation of pro-survival mechanism to rescue ischemic injury, while chronic ER stress generally serves as a detrimental role on nerve cells via triggering diverse pro-apoptotic mechanism. What’s more, the determination of some proteins in UPR during cerebral ischemia to cell fate may have two diametrically opposed results which involves in a specialized set of inflammatory and apoptotic signaling pathways. A reasonable understanding and exploration of the underlying molecular mechanism related to ER stress and cerebral ischemia is a prerequisite for a major breakthrough in stroke treatment in the future. This review focuses on recent findings of the ER stress as well as the progress research of mechanism in ischemic stroke prognosis provide a new treatment idea for recovery of cerebral ischemia.
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Affiliation(s)
- Yu Han
- Department of Sport Rehabilitation, Shanghai University of Sport, Shanghai, China.,Department of Rehabilitation Medicine, Shanghai University of Medicine and Health Sciences Affiliated Zhoupu Hospital, Shanghai, China
| | - Mei Yuan
- Department of Sport Rehabilitation, Shanghai University of Sport, Shanghai, China.,Department of Rehabilitation Medicine, Shanghai University of Medicine and Health Sciences Affiliated Zhoupu Hospital, Shanghai, China
| | - Yi-Sha Guo
- Department of Sport Rehabilitation, Shanghai University of Sport, Shanghai, China.,Department of Rehabilitation Medicine, Shanghai University of Medicine and Health Sciences Affiliated Zhoupu Hospital, Shanghai, China
| | - Xin-Ya Shen
- Department of Rehabilitation Medicine, Shanghai University of Medicine and Health Sciences Affiliated Zhoupu Hospital, Shanghai, China.,Shanghai University of Medicine and Health Sciences Affiliated Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Zhen-Kun Gao
- Department of Rehabilitation Medicine, Shanghai University of Medicine and Health Sciences Affiliated Zhoupu Hospital, Shanghai, China.,Shanghai University of Medicine and Health Sciences Affiliated Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Xia Bi
- Department of Rehabilitation Medicine, Shanghai University of Medicine and Health Sciences Affiliated Zhoupu Hospital, Shanghai, China
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3
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Deshpande LS, DeLorenzo RJ, Churn SB, Parsons JT. Neuronal-Specific Inhibition of Endoplasmic Reticulum Mg 2+/Ca 2+ ATPase Ca 2+ Uptake in a Mixed Primary Hippocampal Culture Model of Status Epilepticus. Brain Sci 2020; 10:brainsci10070438. [PMID: 32664397 PMCID: PMC7407863 DOI: 10.3390/brainsci10070438] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 07/05/2020] [Accepted: 07/07/2020] [Indexed: 11/29/2022] Open
Abstract
Loss of intracellular calcium homeostasis is an established mechanism associated with neuronal dysfunction and status epilepticus. Sequestration of free cytosolic calcium into endoplasmic reticulum by Mg2+/Ca2+ adenosinetriphosphatase (ATPase) is critical for maintenance of intracellular calcium homeostasis. Exposing hippocampal cultures to low-magnesium media is a well-accepted in vitro model of status epilepticus. Using this model, it was shown that endoplasmic reticulum Ca2+ uptake was significantly inhibited in homogenates from cultures demonstrating electrophysiological seizure phenotypes. Calcium uptake was mainly neuronal. However, glial Ca2+ uptake was also significantly inhibited. Viability of neurons exposed to low magnesium was similar to neurons exposed to control solutions. Finally, it was demonstrated that Ca2+ uptake inhibition and intracellular free Ca2+ levels increased in parallel with increasing incubation in low magnesium. The results suggest that inhibition of Mg2+/Ca2+ ATPase-mediated endoplasmic reticulum Ca2+ sequestration contributes to loss of intracellular Ca2+ homeostasis associated with status epilepticus. This study describes for the first time inhibition of endoplasmic reticulum Mg2+/Ca2+ ATPase in a mixed primary hippocampal model of status epilepticus. In combination with animal models of status epilepticus, the cell culture model provides a powerful tool to further elucidate mechanisms that result in inhibition of Mg2+/Ca2+ ATPase and downstream consequences of decreased enzyme activity.
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Affiliation(s)
- Laxmikant S. Deshpande
- Department of Neurology, Virginia Commonwealth University, Richmond, VA 23298, USA; (L.S.D.); (R.J.D.); (S.B.C.)
| | - Robert J. DeLorenzo
- Department of Neurology, Virginia Commonwealth University, Richmond, VA 23298, USA; (L.S.D.); (R.J.D.); (S.B.C.)
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
- Department of Biochemistry and Molecular Biophysics, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Severn B. Churn
- Department of Neurology, Virginia Commonwealth University, Richmond, VA 23298, USA; (L.S.D.); (R.J.D.); (S.B.C.)
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
- Department of Physiology, Virginia Commonwealth University, Richmond, VA 23298, USA
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - J. Travis Parsons
- Department of Neurology, Virginia Commonwealth University, Richmond, VA 23298, USA; (L.S.D.); (R.J.D.); (S.B.C.)
- Correspondence:
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4
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Abstract
Cerebral ischemia is a complex pathology involving a cascade of cellular mechanisms, which deregulate proteostasis and lead to neuronal death. Proteostasis refers to the equilibrium between protein synthesis, folding, transport, and protein degradation. Within the brain proteostasis plays key roles in learning and memory by controlling protein synthesis and degradation. Two important pathways are implicated in the regulation of proteostasis: the unfolded protein response (UPR) and macroautophagy (called hereafter autophagy). Both are necessary for cell survival, however, their over-activation in duration or intensity can lead to cell death. Moreover, UPR and autophagy can activate and potentiate each other to worsen the issue of cerebral ischemia. A better understanding of autophagy and ER stress will allow the development of therapeutic strategies for stroke, both at the acute phase and during recovery. This review summarizes the latest therapeutic advances implicating ER stress or autophagy in cerebral ischemia. We argue that the processes governing proteostasis should be considered together in stroke, rather than focusing either on ER stress or autophagy in isolation.
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Affiliation(s)
- Audrey M Thiebaut
- INSERM, INSERM UMR-S U1237, Physiopathology and Imaging of Neurological Disorders, University of Caen Normandy, Caen, France
| | - Elodie Hedou
- INSERM, INSERM UMR-S U1237, Physiopathology and Imaging of Neurological Disorders, University of Caen Normandy, Caen, France
| | - Stefan J Marciniak
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom.,Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Denis Vivien
- INSERM, INSERM UMR-S U1237, Physiopathology and Imaging of Neurological Disorders, University of Caen Normandy, Caen, France.,Department of Clinical Research, University of Caen Normandy, Caen, France
| | - Benoit D Roussel
- INSERM, INSERM UMR-S U1237, Physiopathology and Imaging of Neurological Disorders, University of Caen Normandy, Caen, France
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5
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Mollereau B, Rzechorzek NM, Roussel BD, Sedru M, Van den Brink DM, Bailly-Maitre B, Palladino F, Medinas DB, Domingos PM, Hunot S, Chandran S, Birman S, Baron T, Vivien D, Duarte CB, Ryoo HD, Steller H, Urano F, Chevet E, Kroemer G, Ciechanover A, Calabrese EJ, Kaufman RJ, Hetz C. Adaptive preconditioning in neurological diseases - therapeutic insights from proteostatic perturbations. Brain Res 2016; 1648:603-616. [PMID: 26923166 PMCID: PMC5010532 DOI: 10.1016/j.brainres.2016.02.033] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 02/16/2016] [Indexed: 02/06/2023]
Abstract
In neurological disorders, both acute and chronic neural stress can disrupt cellular proteostasis, resulting in the generation of pathological protein. However in most cases, neurons adapt to these proteostatic perturbations by activating a range of cellular protective and repair responses, thus maintaining cell function. These interconnected adaptive mechanisms comprise a 'proteostasis network' and include the unfolded protein response, the ubiquitin proteasome system and autophagy. Interestingly, several recent studies have shown that these adaptive responses can be stimulated by preconditioning treatments, which confer resistance to a subsequent toxic challenge - the phenomenon known as hormesis. In this review we discuss the impact of adaptive stress responses stimulated in diverse human neuropathologies including Parkinson׳s disease, Wolfram syndrome, brain ischemia, and brain cancer. Further, we examine how these responses and the molecular pathways they recruit might be exploited for therapeutic gain. This article is part of a Special Issue entitled SI:ER stress.
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Affiliation(s)
- B Mollereau
- Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, F-69007, Lyon, France.
| | - N M Rzechorzek
- Centre for Clinical Brain Sciences, Chancellor's Building, University of Edinburgh, Edinburgh EH16 4SB, United Kingdom; Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Roslin, Midlothian EH25 9RG, United Kingdom
| | - B D Roussel
- Inserm, UMR-S U919 Serine Proteases and Pathophysiology of the Neurovascular Unit, 14000 Caen, France
| | - M Sedru
- Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, F-69007, Lyon, France
| | - D M Van den Brink
- Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, F-69007, Lyon, France
| | - B Bailly-Maitre
- INSERM U1065, C3M, Team 8 (Hepatic Complications in Obesity), Nice, France
| | - F Palladino
- Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, F-69007, Lyon, France
| | - D B Medinas
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile; Center for Molecular Studies of the Cell, Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile; Center for Geroscience, Brain Health and Metabolism, Faculty of Medicine, University of Chile, Santiago, Chile
| | - P M Domingos
- ITQB-UNL, Av. da Republica, EAN, 2780-157 Oeiras, Portugal
| | - S Hunot
- Inserm, U 1127, F-75013 Paris, France; CNRS, UMR 7225, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - S Chandran
- Centre for Clinical Brain Sciences, Chancellor's Building, University of Edinburgh, Edinburgh EH16 4SB, United Kingdom
| | - S Birman
- Genes Circuits Rhythms and Neuropathology, Brain Plasticity Unit, CNRS UMR 8249, ESPCI ParisTech, PSL Research University, 75005 Paris, France
| | - T Baron
- ANSES, French Agency for Food, Environmental and Occupational Health & Safety, Neurodegenerative Diseases Unit, 31, avenue Tony Garnier, 69364 Lyon Cedex 07, France
| | - D Vivien
- Inserm, UMR-S U919 Serine Proteases and Pathophysiology of the Neurovascular Unit, 14000 Caen, France
| | - C B Duarte
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Faculty of Medicine, Rua Larga, and Department of Life Sciences, University of Coimbra, 3004-504 Coimbra, Portugal
| | - H D Ryoo
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - H Steller
- Howard Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
| | - F Urano
- Washington University School of Medicine, Department of Internal Medicine, St. Louis, MO 63110 USA
| | - E Chevet
- Inserm ERL440 "Oncogenesis, Stress, Signaling", Université de Rennes 1, Rennes, France; Centre de Lutte Contre le Cancer Eugène Marquis, Rennes, France
| | - G Kroemer
- Equipe 11 labellisée par la Ligue contre le Cancer, Centre de Recherche des Cordeliers, Paris, France; Cell Biology and Metabolomics platforms, Gustave Roussy Comprehensive Cancer Center, Villejuif, France; INSERM, U1138, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Université Pierre et Marie Curie, Paris, France; Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, Paris, France; Karolinska Institute, Department of Women׳s and Children׳s Health, Karolinska University Hospital, Stockholm, Sweden
| | - A Ciechanover
- The Polak Cancer and Vascular Biology Research Center, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 30196, Israel
| | - E J Calabrese
- Department of Environmental Health Sciences, University of Massachusetts, Morrill I, N344, Amherst, MA 01003, USA
| | - R J Kaufman
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd., La Jolla, CA 92037, USA
| | - C Hetz
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile; Center for Molecular Studies of the Cell, Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile; Center for Geroscience, Brain Health and Metabolism, Faculty of Medicine, University of Chile, Santiago, Chile; Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA
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6
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Caldeira MV, Salazar IL, Curcio M, Canzoniero LMT, Duarte CB. Role of the ubiquitin-proteasome system in brain ischemia: friend or foe? Prog Neurobiol 2013; 112:50-69. [PMID: 24157661 DOI: 10.1016/j.pneurobio.2013.10.003] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 10/08/2013] [Accepted: 10/15/2013] [Indexed: 11/26/2022]
Abstract
The ubiquitin-proteasome system (UPS) is a catalytic machinery that targets numerous cellular proteins for degradation, thus being essential to control a wide range of basic cellular processes and cell survival. Degradation of intracellular proteins via the UPS is a tightly regulated process initiated by tagging a target protein with a specific ubiquitin chain. Neurons are particularly vulnerable to any change in protein composition, and therefore the UPS is a key regulator of neuronal physiology. Alterations in UPS activity may induce pathological responses, ultimately leading to neuronal cell death. Brain ischemia triggers a complex series of biochemical and molecular mechanisms, such as an inflammatory response, an exacerbated production of misfolded and oxidized proteins, due to oxidative stress, and the breakdown of cellular integrity mainly mediated by excitotoxic glutamatergic signaling. Brain ischemia also damages protein degradation pathways which, together with the overproduction of damaged proteins and consequent upregulation of ubiquitin-conjugated proteins, contribute to the accumulation of ubiquitin-containing proteinaceous deposits. Despite recent advances, the factors leading to deposition of such aggregates after cerebral ischemic injury remain poorly understood. This review discusses the current knowledge on the role of the UPS in brain function and the molecular mechanisms contributing to UPS dysfunction in brain ischemia with consequent accumulation of ubiquitin-containing proteins. Chemical inhibitors of the proteasome and small molecule inhibitors of deubiquitinating enzymes, which promote the degradation of proteins by the proteasome, were both shown to provide neuroprotection in brain ischemia, and this apparent contradiction is also discussed in this review.
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Affiliation(s)
- Margarida V Caldeira
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Ivan L Salazar
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Doctoral Programme in Experimental Biology and Biomedicine, Center for Neuroscience and Cell Biology, University of Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra (IIIUC), Portugal
| | - Michele Curcio
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Department of Science and Technology, University of Sannio, Benevento, Italy
| | | | - Carlos B Duarte
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal.
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7
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Bodalia A, Li H, Jackson MF. Loss of endoplasmic reticulum Ca2+ homeostasis: contribution to neuronal cell death during cerebral ischemia. Acta Pharmacol Sin 2013; 34:49-59. [PMID: 23103622 DOI: 10.1038/aps.2012.139] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The loss of Ca(2+) homeostasis during cerebral ischemia is a hallmark of impending neuronal demise. Accordingly, considerable cellular resources are expended in maintaining low resting cytosolic levels of Ca(2+). These include contributions by a host of proteins involved in the sequestration and transport of Ca(2+), many of which are expressed within intracellular organelles, including lysosomes, mitochondria as well as the endoplasmic reticulum (ER). Ca(2+) sequestration by the ER contributes to cytosolic Ca(2+) dynamics and homeostasis. Furthermore, within the ER Ca(2+) plays a central role in regulating a host of physiological processes. Conversely, impaired ER Ca(2+) homeostasis is an important trigger of pathological processes. Here we review a growing body of evidence suggesting that ER dysfunction is an important factor contributing to neuronal injury and loss post-ischemia. Specifically, the contribution of the ER to cytosolic Ca(2+) elevations during ischemia will be considered, as will the signalling cascades recruited as a consequence of disrupting ER homeostasis and function.
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8
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He W, Hu Z. The Role of the Golgi-Resident SPCA Ca2+/Mn2+ Pump in Ionic Homeostasis and Neural Function. Neurochem Res 2012; 37:455-68. [DOI: 10.1007/s11064-011-0644-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Revised: 10/28/2011] [Accepted: 11/02/2011] [Indexed: 12/23/2022]
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9
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Abstract
The endoplasmic reticulum (ER) as an intracellular Ca(2+) store not only sets up cytosolic Ca(2+) signals, but, among other functions, also assembles and folds newly synthesized proteins. Alterations in ER homeostasis, including severe Ca(2+) depletion, are an upstream event in the pathophysiology of many diseases. On the one hand, insufficient release of activator Ca(2+) may no longer sustain essential cell functions. On the other hand, loss of luminal Ca(2+) causes ER stress and activates an unfolded protein response, which, depending on the duration and severity of the stress, can reestablish normal ER function or lead to cell death. We will review these various diseases by mainly focusing on the mechanisms that cause ER Ca(2+) depletion.
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Affiliation(s)
- Djalila Mekahli
- Laboratory of Molecular and Cellular Signaling, Department of Molecular Cell Biology, KU Leuven Campus Gasthuisberg O&N I, Belgium
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10
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Duan SR, Wang JX, Wang J, Xu R, Zhao JK, Wang DS. Ischemia induces endoplasmic reticulum stress and cell apoptosis in human brain. Neurosci Lett 2010; 475:132-5. [PMID: 20347937 DOI: 10.1016/j.neulet.2010.03.058] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2009] [Revised: 03/19/2010] [Accepted: 03/20/2010] [Indexed: 01/23/2023]
Abstract
In animal models, endoplasmic reticulum (ER) stress and apoptosis take place around cerebral infarction areas during ischemia, which presumably protect tissues from necroses-induced injury as well as promote cells toward death. We examined whether these pathological changes, especially temporal occurrence, were present in patients who suffered from cerebral ischemia. The studies by immunohistochemistry show that ER chaperone glucose-regulated protein (GRP78) and caspase-9 elevate around infarction areas. The experiments by terminal deoxynucleotidy transferase-mediated 2'-deoxyuridine 5'-triphosphate-biotin nick-end labeling (TUNEL) illustrate that TUNEL-positive cells are higher around infarction tissues than controls. Moreover, GRP78, caspase-9 and TUNEL cells emerge one after another during ischemia. In conclusion, ER stress, apoptosis initiation and DNA fragment develop sequentially in ischemic human brain. ER stress during excessive ischemia stimulates apoptotic cell death beyond activating a defense for nerve cells being away from injury.
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Affiliation(s)
- Shu-Rong Duan
- Department of Neurology, The First Affiliated Hospital of Harbin Medical University, 23 Youzheng Street, Nangang District, Harbin 150001, China
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11
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Pavlíková M, Tatarková Z, Sivonová M, Kaplan P, Krizanová O, Lehotský J. Alterations induced by ischemic preconditioning on secretory pathways Ca2+-ATPase (SPCA) gene expression and oxidative damage after global cerebral ischemia/reperfusion in rats. Cell Mol Neurobiol 2009; 29:909-16. [PMID: 19288187 DOI: 10.1007/s10571-009-9374-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Accepted: 02/19/2009] [Indexed: 11/30/2022]
Abstract
Ischemic preconditioning (IPC) represents the phenomenon of CNC adaptation, which results in increased tolerance of CNS to lethal ischemia. Brain ischemia/reperfusion (IRI) initiates a catastrophic cascade in which many subcellular organelles play an important role. The Golgi apparatus, which is a part of secretory pathways (SP), represents the Ca(2+) store and regulates secretion of proteins for growth/reorganization of neuronal circuit by secretory Ca(2+)ATPases (SPCA1). The purpose of this study is to evaluate the effect of IRI and preconditioning on SPCA1 gene expression and oxidative damage after 4-vessel occlusion for 15 min and after being exposed to different reperfusion periods. Rats were preconditioned by 5 min of sub-lethal ischemia and 2 days later, 15 min of lethal ischemia was induced. Our experiments conclusively showed IRI-induced depression of SPCA activity and lipo- and protein oxidation in rat hippocampal membranes. IRI also activates the induction of SPCA1 gene expression in later reperfusion periods. IPC partially suppresses lipo- and protein oxidation in hippocampal membranes and leads to partiall rovery of the ischemic-induced depression of SPCA activity. In addition, IPC initiates earlier cellular response to the injury by the significant elevation of mRNA expression to 142% comparing to 1 h of corresponding reperfusion and to 11% comparing to 24 h of corresponding reperfusion, respectively. Similar patterns were observed on the translational level by Western blot analysis. Our results indicate the specific SPCA1 expression pattern in ischemic hippocampus. It also shows that the SPCA expression and the post-translational changes induced by ischemia are modulated by the IPC. This might serve to understand the molecular mechanisms involved in the structural integrity and function of the SP after ischemic challenge. It also suggests that there is a correlation of SPCA function with the role of SP in the response to pre-ischemic challenge.
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Affiliation(s)
- M Pavlíková
- Department of Medical Biochemistry, Jessenius Faculty of Medicine, Comenius University, 036 01 Martin, Slovak Republic
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12
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Vosler PS, Brennan CS, Chen J. Calpain-mediated signaling mechanisms in neuronal injury and neurodegeneration. Mol Neurobiol 2008; 38:78-100. [PMID: 18686046 DOI: 10.1007/s12035-008-8036-x] [Citation(s) in RCA: 275] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2008] [Accepted: 07/17/2008] [Indexed: 12/19/2022]
Abstract
Calpain is a ubiquitous calcium-sensitive protease that is essential for normal physiologic neuronal function. However, alterations in calcium homeostasis lead to persistent, pathologic activation of calpain in a number of neurodegenerative diseases. Pathologic activation of calpain results in the cleavage of a number of neuronal substrates that negatively affect neuronal structure and function, leading to inhibition of essential neuronal survival mechanisms. In this review, we examine the mechanistic underpinnings of calcium dysregulation resulting in calpain activation in the acute neurodegenerative diseases such as cerebral ischemia and in the chronic neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, prion-related encephalopathy, and amylotrophic lateral sclerosis. The premise of this paper is that analysis of the signaling and transcriptional consequences of calpain-mediated cleavage of its various substrates for any neurodegenerative disease can be extrapolated to all of the neurodegenerative diseases vulnerable to calcium dysregulation.
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Abstract
The calpain family of proteases is causally linked to postischemic neurodegeneration. However, the precise mechanisms by which calpains contribute to postischemic neuronal death have not been fully elucidated. This review outlines the key features of the calpain system, and the evidence for its causal role in postischemic neuronal pathology. Furthermore, the consequences of specific calpain substrate cleavage at various subcellular locations are explored. Calpain substrates within synapses, plasma membrane, endoplasmic reticulum, lysosomes, mitochondria, and the nucleus, as well as the overall effect of postischemic calpain activity on calcium regulation and cell death signaling are considered. Finally, potential pathways for calpain-mediated neurodegeneration are outlined in an effort to guide future studies aimed at understanding the downstream pathology of postischemic calpain activity and identifying optimal therapeutic strategies.
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Affiliation(s)
- Matthew B Bevers
- Department of Emergency Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-4283, USA
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Fernandes AM, Landeira-Fernandez AM, Souza-Santos P, Carvalho-Alves PC, Castilho RF. 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] [What about the content of this article? (0)] [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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15
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Vázquez-López A, Sierra-Paredes G, Sierra-Marcuño G. Anticonvulsant effect of the calcineurin inhibitor ascomycin on seizures induced by picrotoxin microperfusion in the rat hippocampus. Pharmacol Biochem Behav 2006; 84:511-6. [PMID: 16872668 DOI: 10.1016/j.pbb.2006.06.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2006] [Revised: 06/13/2006] [Accepted: 06/21/2006] [Indexed: 11/23/2022]
Abstract
The potential in vivo anticonvulsant effect of calcineurin (protein phosphatase 2B) inhibitor ascomycin against seizures induced by intrahippocampal microdialysis of picrotoxin was examined in the present study. After establishing individual picrotoxin seizure thresholds, ascomycin was continually microperfused into the rat hippocampus through microdialysis probes at concentrations 10, 50 and 100 microM. No behavioral or electroencephalographic effects were observed during microperfusion of ascomycin alone. Low concentrations (10 microM) of ascomycin did not prevent picrotoxin seizures, however, 50 and 100 microM ascomycin showed antiepileptic effect, completely suppressing seizures in 41.7% and 75% of the animals studied respectively. Mean seizure duration and mean number of seizures were significantly reduced (P < 0.01) by microperfusion of 100 microM ascomycin. Calcineurin activity might be involved in the biochemical changes leading to picrotoxin-induced epileptic seizures. The present findings provide additional in vivo evidence of the involvement of phosphorylation/dephosphorylation mechanisms in the development of epileptic seizures, suggesting that calcineurin modulation may be a possible strategy in the search for new anticonvulsant drugs.
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Affiliation(s)
- Araceli Vázquez-López
- Neuroscience Division, Department of Biochemistry and Molecular Biology, School of Medicine, University of Santiago, San Francisco 1, 15782 Santiago de Compostela, Spain
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16
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Larsen GA, Skjellegrind HK, Moe MC, Vinje ML, Berg-Johnsen J. Endoplasmic reticulum dysfunction and Ca2+ deregulation in isolated CA1 neurons during oxygen and glucose deprivation. Neurochem Res 2005; 30:651-9. [PMID: 16176069 DOI: 10.1007/s11064-005-2753-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Intracellular calcium ([Ca2+]i) plays a pivotal role in neuronal ischemia. The aim of the present study was to investigate the routes of Ca2+ entry during non-excitotoxic oxygen and glucose deprivation (OGD) in acutely dissociated rat CA1 neurons. During OGD the fluo-3/fura red ratio reflecting [Ca2+]i increased rapidly and irreversibly. [Ca2+]i increased to the same degree in Ca2 + depleted medium, and also when both the ryanodine receptors (RyR) and the inositol 1,4,5-trisphosphate (IP3) receptors were blocked. When the endoplasmic reticulum (ER) Ca2+ stores were emptied with thapsigargin no increase in [Ca2+]i was observed independent of extracellular Ca2+. The OGD induced Ca2+ deregulation in isolated CA1 neurons is not prevented by removing Ca2+, or by blocking the IP3- or RyR receptors. However, when SERCA was blocked, no increase in [Ca2+]i was observed suggesting that SERCA dysfunction represents an important mechanism for ischemic Ca2+ overload.
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Affiliation(s)
- Geir Arne Larsen
- Institute for Surgical Research, Department of Neurosurgery, National Hospital, Rikshospitalet, N-0027, Oslo, Norway.
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17
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Abstract
We review studies of endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) following cerebral ischemia and reperfusion (I/R). The UPR is a cell stress program activated when misfolded proteins accumulate in the ER lumen. UPR activation causes: (i) a PERK-mediated phosphorylation of eIF2alpha, inhibiting protein synthesis to prevent further accumulation of unfolded proteins in the ER and (ii) upregulation of genes coding for ER-resident enzymes and chaperones and others, via eIF2alpha(p), and ATF6 and IRE1 activation. UPR-induced transcription increases capacity of the ER to process misfolded proteins. If ER stress and the UPR are prolonged, apoptosis ensues. Multiple forms of ER stress have been observed following brain I/R. The UPR following brain I/R is not isomorphic between in vivo I/R models and in vitro cell culture systems with pharmacological UPR induction. Although PERK and IRE1 are activated in the initial hours of reperfusion, total PERK decreases, ATF6 is not activated, and there is delayed appearance of UPR-induced mRNAs. Thus, multiple damage mechanisms associated with brain I/R alter UPR expression and contribute to a pro-apoptotic phenotype in neurons. Insights resulting from these studies will be important for the development of therapies to halt neuronal death following brain I/R.
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Affiliation(s)
- Donald J DeGracia
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
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18
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Parsons JT, Sun DA, DeLorenzo RJ, Churn SB. Neuronal-specific endoplasmic reticulum Mg2+/Ca2+ ATPase Ca2+ sequestration in mixed primary hippocampal culture homogenates. Anal Biochem 2004; 330:130-9. [PMID: 15183771 DOI: 10.1016/j.ab.2004.03.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2003] [Indexed: 11/16/2022]
Abstract
Endoplasmic reticulum Mg(2+)/Ca(2+) ATPase Ca(2+) sequestration is crucial for maintenance of neuronal Ca(2+) homeostasis. The use of cell culture in conjunction with modern Ca(2+) imaging techniques has been invaluable in elucidating these mechanisms. While imaging protocols evaluate endoplasmic reticulum Ca(2+) loads, measurement of Mg(2+)/Ca(2+) ATPase activity is indirect, comparing cytosolic Ca(2+) levels in the presence or absence of the Mg(2+)/Ca(2+) ATPase inhibitor thapsigargin. Direct measurement of Mg(2+)/Ca(2+) ATPase by isolation of microsomes is impossible due to the minuscule amounts of protein yielded from cultures used for imaging. In the current study, endoplasmic reticulum Mg(2+)/Ca(2+) ATPase Ca(2+) sequestration was measured in mixed homogenates of neurons and glia from primary hippocampal cultures. It was demonstrated that Ca(2+) uptake was mediated by the endoplasmic reticulum Mg(2+)/Ca(2+) ATPase due to its dependence on ATP and Mg(2+), enhancement by oxalate, and inhibition by thapsigargin. It was also shown that neuronal Ca(2+) uptake, mediated by the type 2 sarco(endo)plasmic reticulum Ca(2+) ATPase isoform, could be distinguished from glial Ca(2+) uptake in homogenates composed of neurons and glia. Finally, it was revealed that Ca(2+) uptake was sensitive to incubation on ice, extremely labile in the absence of protease inhibitors, and significantly more stable under storage conditions at -80 degrees C.
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Affiliation(s)
- J Travis Parsons
- Department of Neurology, Virginia Commonwealth University, PO Box 980599 (USPS), 1217 E Marshall St, MSB-619 (UPS, Fed-Ex), Richmond, VA 23298, USA.
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19
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Abstract
Changes in neuronal calcium activity in the various subcellular compartments have divergent effects on affected cells. In the cytoplasm and mitochondria, where calcium activity is normally low, a prolonged excessive rise in free calcium levels is believed to be toxic, in the endoplasmic reticulum (ER), in contrast, calcium activity is relatively high and severe stress is caused by a depletion of ER calcium stores. Besides its role in cellular calcium signaling, the ER is the site where membrane and secretory proteins are folded and processed. These calcium-dependent processes are fundamental to normal cell functioning. Under conditions of ER dysfunction unfolded proteins accumulate in the ER lumen, a signal responsible for activation of the unfolded protein response (UPR) and the ER-associated degradation (ERAD). UPR is characterized by activation of two ER-resident kinases, PKR-like ER kinase (PERK) and IRE1. PERK induces phosphorylation of the eukaryotic initiation factor (eIF2alpha), resulting in a shut-down of translation at the initiation step. This stress response is needed to block new synthesis of proteins that cannot be correctly folded, and thus to protect cells from the effect of unfolded proteins which tend to form toxic aggregates. IRE1, on the other hand, is turned after activation into an endonuclease that cuts out a sequence of 26 bases from the coding region of xbp1 mRNA. Processed xbp1 mRNA is translated into the respective protein, an active transcription factor specific for ER stress genes such as grp78. In acute disorders and degenerative diseases, the ER calcium pool is a primary target of toxic metabolites or intermediates, such as oxygen free radicals, produced during the pathological process. Affected neurons need to activate the entire UPR to cope with the severe form of stress induced by ER dysfunction. This stress response is however hindered under conditions where protein synthesis is suppressed to such an extent that processed xbp1 mRNA is not translated into the processed XBP1 protein (XBP1(proc)). Furthermore, activation of ERAD is important for the degradation of unfolded proteins through the ubiquitin/proteasomal pathway, which is impaired in acute disorders and degenerative diseases, resulting in further ER stress. ER functioning is thus impaired in two different ways: first by the direct action of toxic intermediates, produced in the course of the pathological process, hindering vital ER reactions, and second by the inability of cells to fully activate UPR and ERAD, leaving them unable to withstand the severe form of stress induced by ER dysfunction.
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Affiliation(s)
- Wulf Paschen
- Department of Experimental Neurology, Max-Planck-Institute for Neurological Research, 50931 Koeln, Germany.
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20
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DeGracia DJ, Kumar R, Owen CR, Krause GS, White BC. Molecular pathways of protein synthesis inhibition during brain reperfusion: implications for neuronal survival or death. J Cereb Blood Flow Metab 2002; 22:127-41. [PMID: 11823711 DOI: 10.1097/00004647-200202000-00001] [Citation(s) in RCA: 184] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protein synthesis inhibition occurs in neurons immediately on reperfusion after ischemia and involves at least alterations in eukaryotic initiation factors 2 (eIF2) and 4 (eIF4). Phosphorylation of the alpha subunit of eIF2 [eIF2(alphaP)] by the endoplasmic reticulum transmembrane eIF2alpha kinase PERK occurs immediately on reperfusion and inhibits translation initiation. PERK activation, along with depletion of endoplasmic reticulum Ca2+ and inhibition of the endoplasmic reticulum Ca2+ -ATPase, SERCA2b, indicate that an endoplasmic reticulum unfolded protein response occurs as a consequence of brain ischemia and reperfusion. In mammals, the upstream unfolded protein response components PERK, IRE1, and ATF6 activate prosurvivial mechanisms (e.g., transcription of GRP78, PDI, SERCA2b ) and proapoptotic mechanisms (i.e., activation of Jun N-terminal kinases, caspase-12, and CHOP transcription). Sustained eIF2(alphaP) is proapoptotic by inducing the synthesis of ATF4, the CHOP transcription factor, through "bypass scanning" of 5' upstream open-reading frames in ATF4 messenger RNA; these upstream open-reading frames normally inhibit access to the ATF4 coding sequence. Brain ischemia and reperfusion also induce mu-calpain-mediated or caspase-3-mediated proteolysis of eIF4G, which shifts message selection to m 7 G-cap-independent translation initiation of messenger RNAs containing internal ribosome entry sites. This internal ribosome entry site-mediated translation initiation (i.e., for apoptosis-activating factor-1 and death-associated protein-5) can also promote apoptosis. Thus, alterations in eIF2 and eIF4 have major implications for which messenger RNAs are translated by residual protein synthesis in neurons during brain reperfusion, in turn constraining protein expression of changes in gene transcription induced by ischemia and reperfusion. Therefore, our current understanding shifts the focus from protein synthesis inhibition to the molecular pathways that underlie this inhibition, and the role that these pathways play in prosurvival and proapoptotic processes that may be differentially expressed in vulnerable and resistant regions of the reperfused brain.
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Affiliation(s)
- Donald J DeGracia
- Department of Emergency Medicine, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
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21
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Parsons JT, Churn SB, DeLorenzo RJ. Chronic inhibition of cortex microsomal Mg(2+)/Ca(2+) ATPase-mediated Ca(2+) uptake in the rat pilocarpine model following epileptogenesis. J Neurochem 2001; 79:319-27. [PMID: 11677260 DOI: 10.1046/j.1471-4159.2001.00576.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In the rat pilocarpine model, 1 h of status epilepticus caused significant inhibition of Mg(2+)/Ca(2+) ATPase-mediated Ca(2+) uptake in cortex endoplasmic reticulum (microsomes) isolated immediately after the status episode. The rat pilocarpine model is also an established model of acquired epilepsy. Several weeks after the initial status epilepticus episode, the rats develop spontaneous recurrent seizures, or epilepsy. To determine whether inhibition of Ca(2+) uptake persists after the establishment of epilepsy, Ca(2+) uptake was studied in cortical microsomes isolated from rats displaying spontaneous recurrent seizures for 1 year. The initial rate and total Ca(2+) uptake in microsomes from epileptic animals remained significantly inhibited 1 year after the expression of epilepsy compared to age-matched controls. The inhibition of Ca(2+) uptake was not due to individual seizures nor an artifact of increased Ca(2+) release from epileptic microsomes. In addition, the decreased Ca(2+) uptake was not due to either selective isolation of damaged epileptic microsomes from the homogenate or decreased Mg(2+)/Ca(2+) ATPase protein in the epileptic microsomes. The data demonstrate that inhibition of microsomal Mg(2+)/Ca(2+) ATPase-mediated Ca(2+) uptake in the pilocarpine model may underlie some of the long-term plasticity changes associated with epileptogenesis.
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Affiliation(s)
- J T Parsons
- Department of Neurology, Medical College of Virginia Commonwealth University, Richmond, Virginia 23298-0599, USA.
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22
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Berman MC. Slippage and uncoupling in P-type cation pumps; implications for energy transduction mechanisms and regulation of metabolism. Biochim Biophys Acta 2001; 1513:95-121. [PMID: 11470083 DOI: 10.1016/s0005-2736(01)00356-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
P-type ATPases couple scalar and vectorial events under optimized states. A number of procedures and conditions lead to uncoupling or slippage. A key branching point in the catalytic cycle is at the cation-bound form of E(1)-P, where isomerization to E(2)-P leads to coupled transport, and hydrolysis leads to uncoupled release of cations to the cis membrane surface. The phenomenon of slippage supports a channel model for active transport. Ability to occlude cations within the channel is essential for coupling. Uncoupling and slippage appear to be inherent properties of P-type cation pumps, and are significant contributors to standard metabolic rate. Heat production is favored in the uncoupled state. A number of disease conditions, include ageing, ischemia and cardiac failure, result in uncoupling of either the Ca(2+)-ATPase or Na(+)/K(+)-ATPase.
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Affiliation(s)
- M C Berman
- Division of Chemical Pathology, Health Sciences Faculty, University of Cape Town, Observatory 7925, Cape Town, South Africa.
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23
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Kurz JE, Sheets D, Parsons JT, Rana A, Delorenzo RJ, Churn SB. A significant increase in both basal and maximal calcineurin activity in the rat pilocarpine model of status epilepticus. J Neurochem 2001; 78:304-15. [PMID: 11461966 DOI: 10.1046/j.1471-4159.2001.00426.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study focused on the effects of status epilepticus on the activity of calcineurin, a neuronally enriched, calcium-dependent phosphatase. Calcineurin is an important modulator of many neuronal processes, including learning and memory, induction of apoptosis, receptor function and neuronal excitability. Therefore, a status epilepticus-induced alteration of the activity of this important phosphatase would have significant physiological implications. Status epilepticus was induced by pilocarpine injection and allowed to continue for 60 min. Brain region homogenates were then assayed for calcineurin activity by dephosphorylation of p-nitrophenol phosphate. A significant status epilepticus-dependent increase in both basal and Mn(2+)-dependent calcineurin activity was observed in homogenates isolated from the cortex and hippocampus, but not the cerebellum. This increase was resistant to 150 nM okadaic acid, but sensitive to 50 microM okadaic acid. The increase in basal activity was also resistant to 100 microM sodium orthovanadate. Both maximal dephosphorylation rate and substrate affinity were increased following status epilepticus. However, the increase in calcineurin activity was not found to be due to an increase in calcineurin enzyme levels. Finally, increase in calcineurin activity was found to be NMDA-receptor activation dependent. The data demonstrate that status epilepticus resulted in a significant increase in both basal and maximal calcineurin activity.
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Affiliation(s)
- J E Kurz
- Department of Biology, Virginia Commonwealth University, Richmond, Virginia, USA
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Parsons JT, Churn SB, Kochan LD, DeLorenzo RJ. Pilocarpine-induced status epilepticus causes N-methyl-D-aspartate receptor-dependent inhibition of microsomal Mg(2+)/Ca(2+) ATPase-mediated Ca(2+) uptake. J Neurochem 2000; 75:1209-18. [PMID: 10936204 DOI: 10.1046/j.1471-4159.2000.0751209.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Status epilepticus is associated with sustained and elevated levels of cytosolic Ca(2+). To elucidate the mechanisms associated with changes of cytosolic Ca(2+) after status epilepticus, this study was initiated to evaluate the effect of pilocarpine-induced status epilepticus on Mg(2+)/Ca(2+) ATPase-mediated Ca(2+) uptake in microsomes isolated from rat cortex, because the Ca(2+) uptake mechanism plays a major role in regulating intracellular Ca(2+) levels. The data demonstrated that the initial rate and overall Ca(2+) uptake in microsomes from pilocarpine treated animals were significantly inhibited compared with those in microsomes from saline-treated control animals. It was also shown that the inhibition of Ca(2+) uptake caused by status epilepticus was not an artifact of increased Ca(2+) release from microsomes, selective isolation of damaged microsomes from the homogenate, or decreased Mg(2+)/Ca(2+) ATPase protein in the microsomes. Pretreatment with the NMDA antagonist dizocilpine maleate blocked status epilepticus-induced inhibition of the initial rate and overall Ca(2+) uptake. The data suggest that inhibition of microsomal Mg(2+)/Ca(2+) ATPase Ca(2+) uptake is involved in NMDA-dependent deregulation of cytosolic Ca(2+) homeostasis associated with status epilepticus.
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Affiliation(s)
- J T Parsons
- Department of Neurology, Medical College of Virginia Commonwealth University, Richmond, Virginia 23298-0599, USA
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Abstract
This review discusses the experimental and clinical data which indicate that chronic cerebral hypoperfusion can affect metabolic, anatomic, and cognitive function adversely. In aged but not young animals, chronic brain hypoperfusion results in regional pre- and post-synaptic changes, protein synthesis abnormalities, energy metabolic dysregulation, reduced glucose utilization, cholinergic receptor loss, and visuo-spatial memory deficits. Additionally, aging animals that are kept for prolonged periods of time after chronic brain hypoperfusion, also develop brain capillary degeneration in CA1 hippocampus and neuronal damage extending from the hippocampal region to the temporo-parietal cortex where neurodegenerative tissue atrophy eventually forms. All these pathologic events occur in rodents in the absence of senile plaques and neurofibrillary tangles. Alzheimer brains reveal similar biochemical and structural changes as those experimentally induced in aging animals. Moreover, regional cerebral hypoperfusion is one of the earlier (if not the earliest) clinical manifestations in both the sporadic and familial forms of Alzheimer's disease. In addition, therapy that improves or increases cerebral perfusion is generally of some benefit to Alzheimer patients. Conversely, a variety of disorders with different etiologies that impair or diminish cerebral perfusion are reported to be risk factors for this dementia. These findings have prompted us to propose the concept that advanced aging in the presence of a vascular risk factor can converge to create a critically attained threshold of cerebral hypoperfusion (CATCH) that triggers regional brain microcirculatory disturbances and impairs optimal delivery of energy substrates needed for normal brain cell function. The outcome of this defect generates a chain of events leading to the progressive evolution of brain metabolic, cognitive and tissue pathology that characterize Alzheimer's disease. The possible role of CATCH in familial and early onset Alzheimer's disease is briefly discussed from a theoretical vantagepoint. The growing and most recent evidence in support of the CATCH concept is the focus of this review.
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Affiliation(s)
- J C de la Torre
- Department of Neurosciences (MTF-0624), University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0624, USA.
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