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Csordás G, Weaver D, Várnai P, Hajnóczky G. Supralinear Dependence of the IP 3 Receptor-to-Mitochondria Local Ca 2+ Transfer on the Endoplasmic Reticulum Ca 2+ Loading. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2024; 7:25152564241229273. [PMID: 38362008 PMCID: PMC10868505 DOI: 10.1177/25152564241229273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 12/31/2023] [Accepted: 01/12/2024] [Indexed: 02/17/2024]
Abstract
Calcium signal propagation from endoplasmic reticulum (ER) to mitochondria regulates a multitude of mitochondrial and cell functions, including oxidative ATP production and cell fate decisions. Ca2+ transfer is optimal at the ER-mitochondrial contacts, where inositol 1,4,5-trisphosphate (IP3) receptors (IP3R) can locally expose the mitochondrial Ca2+ uniporter (mtCU) to high [Ca2+] nanodomains. The Ca2+ loading state of the ER (Ca2 + ER) can vary broadly in physiological and pathological scenarios, however, the correlation between Ca2 + ER and the local Ca2+ transfer is unclear. Here, we studied IP3-induced Ca2+ transfer to mitochondria at different Ca2 + ER in intact and permeabilized RBL-2H3 cells via fluorescence measurements of cytoplasmic [Ca2+] ([Ca2+]c) and mitochondrial matrix [Ca2+] ([Ca2+]m). Preincubation of intact cells in high versus low extracellular [Ca2+] caused disproportionally greater increase in [Ca2+]m than [Ca2+]c responses to IP3-mobilizing agonist. Increasing Ca2 + ER by small Ca2+ boluses in suspensions of permeabilized cells supralinearly enhanced the mitochondrial Ca2+ uptake from IP3-induced Ca2+ release. The IP3-induced local [Ca2+] spikes exposing the mitochondrial surface measured using a genetically targeted sensor appeared to linearly correlate with Ca2 + ER, indicating that amplification happened in the mitochondria. Indeed, overexpression of an EF-hand deficient mutant of the mtCU gatekeeper MICU1 reduced the cooperativity of mitochondrial Ca2+ uptake. Interestingly, the IP3-induced [Ca2+]m signal plateaued at high Ca2 + ER, indicating activation of a matrix Ca2+ binding/chelating species. Mitochondria thus seem to maintain a "working [Ca2+]m range" via a low-affinity and high-capacity buffer species, and the ER loading steeply enhances the IP3R-linked [Ca2+]m signals in this working range.
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Affiliation(s)
- György Csordás
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - David Weaver
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Péter Várnai
- Department of Physiology, Semmelweis Medical University, Budapest, Hungary
| | - György Hajnóczky
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
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2
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Resende R, Fernandes T, Pereira AC, Marques AP, Pereira CF. Endoplasmic Reticulum-Mitochondria Contacts Modulate Reactive Oxygen Species-Mediated Signaling and Oxidative Stress in Brain Disorders: The Key Role of Sigma-1 Receptor. Antioxid Redox Signal 2022; 37:758-780. [PMID: 35369731 DOI: 10.1089/ars.2020.8231] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Significance: Mitochondria-Associated Membranes (MAMs) are highly dynamic endoplasmic reticulum (ER)-mitochondria contact sites that, due to the transfer of lipids and Ca2+ between these organelles, modulate several physiologic processes, such as ER stress response, mitochondrial bioenergetics and fission/fusion events, autophagy, and inflammation. In addition, these contacts are implicated in the modulation of the cellular redox status since several MAMs-resident proteins are involved in the generation of reactive oxygen species (ROS), which can act as both signaling mediators and deleterious molecules, depending on their intracellular levels. Recent Advances: In the past few years, structural and functional alterations of MAMs have been associated with the pathophysiology of several neurodegenerative diseases that are closely associated with the impairment of several MAMs-associated events, including perturbation of the redox state on the accumulation of high ROS levels. Critical Issues: Inter-organelle contacts must be tightly regulated to preserve cellular functioning by maintaining Ca2+ and protein homeostasis, lipid metabolism, mitochondrial dynamics and energy production, as well as ROS signaling. Simultaneously, these contacts should avoid mitochondrial Ca2+ overload, which might lead to energetic deficits and deleterious ROS accumulation, culminating in oxidative stress-induced activation of apoptotic cell death pathways, which are common features of many neurodegenerative diseases. Future Directions: Given that Sig-1R is an ER resident chaperone that is highly enriched at the MAMs and that controls ER to mitochondria Ca2+ flux, as well as oxidative and ER stress responses, its potential as a therapeutic target for neurodegenerative diseases such as Amyotrophic Lateral Sclerosis, Alzheimer, Parkinson, and Huntington diseases should be further explored. Antioxid. Redox Signal. 37, 758-780.
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Affiliation(s)
- Rosa Resende
- Center for Neuroscience and Cell Biology, Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal
- Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Tânia Fernandes
- Center for Neuroscience and Cell Biology, Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Ana Catarina Pereira
- Center for Neuroscience and Cell Biology, Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Ana Patrícia Marques
- Center for Neuroscience and Cell Biology, Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal
- Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Cláudia Fragão Pereira
- Center for Neuroscience and Cell Biology, Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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3
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Glycoursodeoxycholic acid ameliorates diet-induced metabolic disorders with inhibiting endoplasmic reticulum stress. Clin Sci (Lond) 2021; 135:1689-1706. [PMID: 34236076 PMCID: PMC8302808 DOI: 10.1042/cs20210198] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 06/30/2021] [Accepted: 07/08/2021] [Indexed: 12/12/2022]
Abstract
Recent studies reveal that bile acid metabolite composition and its metabolism are changed in metabolic disorders, such as obesity, type 2 diabetes and metabolic associated fatty liver disease (MAFLD), yet its role and the mechanism remain largely unknown. In the present study, metabolomic analysis of 163 serum and stool samples of our metabolic disease cohort was performed, and we identified glycoursodeoxycholic acid (GUDCA), glycine-conjugated bile acid produced from intestinal bacteria, was decreased in both serum and stool samples from patients with hyperglycemia. RNA-sequencing and quantitative PCR results indicated that GUDCA alleviated endoplasmic reticulum (ER) stress in livers of high fat diet (HFD)-fed mice without alteration of liver metabolism. In vitro, GUDCA reduced palmitic acid induced-ER stress and -apoptosis, as well as stabilized calcium homeostasis. In vivo, GUDCA exerted effects on amelioration of HFD-induced insulin resistance and hepatic steatosis. In parallel, ER stress and apoptosis were decreased in GUDCA-treated mice as compared with vehicle-treated mice in liver. These findings demonstrate that reduced GUDCA is an indicator of hyperglycemia. Supplementation of GUDCA could be an option for the treatment of diet-induced metabolic disorders, including insulin resistance and hepatic steatosis, with inhibiting ER stress.
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4
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He Q, Liu H, Deng S, Chen X, Li D, Jiang X, Zeng W, Lu W. The Golgi Apparatus May Be a Potential Therapeutic Target for Apoptosis-Related Neurological Diseases. Front Cell Dev Biol 2020; 8:830. [PMID: 33015040 PMCID: PMC7493689 DOI: 10.3389/fcell.2020.00830] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 08/04/2020] [Indexed: 01/04/2023] Open
Abstract
Increasing evidence shows that, in addition to the classical function of protein processing and transport, the Golgi apparatus (GA) is also involved in apoptosis, one of the most common forms of cell death. The structure and the function of the GA is damaged during apoptosis. However, the specific effect of the GA on the apoptosis process is unclear; it may be involved in initiating or promoting apoptosis, or it may inhibit apoptosis. Golgi-related apoptosis is associated with a variety of neurological diseases including glioma, Alzheimer’s disease (AD), Parkinson’s disease (PD), and ischemic stroke. This review summarizes the changes and the possible mechanisms of Golgi structure and function during apoptosis. In addition, we also explore the possible mechanisms by which the GA regulates apoptosis and summarize the potential relationship between the Golgi and certain neurological diseases from the perspective of apoptosis. Elucidation of the interaction between the GA and apoptosis broadens our understanding of the pathological mechanisms of neurological diseases and provides new research directions for the treatment of these diseases. Therefore, we propose that the GA may be a potential therapeutic target for apoptosis-related neurological diseases.
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Affiliation(s)
- Qiang He
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Hui Liu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Shuwen Deng
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Xiqian Chen
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Dong Li
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Xuan Jiang
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Wenbo Zeng
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Wei Lu
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, China
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5
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McDonnell SJ, Spiller DG, White MRH, Prior IA, Paraoan L. ER stress-linked autophagy stabilizes apoptosis effector PERP and triggers its co-localization with SERCA2b at ER-plasma membrane junctions. Cell Death Discov 2019; 5:132. [PMID: 31508245 PMCID: PMC6718399 DOI: 10.1038/s41420-019-0212-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 07/24/2019] [Accepted: 07/29/2019] [Indexed: 01/01/2023] Open
Abstract
Specific molecular interactions that underpin the switch between ER stress-triggered autophagy-mediated cellular repair and cellular death by apoptosis are not characterized. This study reports the unexpected interaction elicited by ER stress between the plasma membrane (PM)-localized apoptosis effector PERP and the ER Ca2+ pump SERCA2b. We show that the p53 effector PERP, which specifically induces apoptosis when expressed above a threshold level, has a heterogeneous distribution across the PM of un-stressed cells and is actively turned over by the lysosome. PERP is upregulated following sustained starvation-induced autophagy, which precedes the onset of apoptosis indicating that PERP protein levels are controlled by a lysosomal pathway that is sensitive to cellular physiological state. Furthermore, ER stress stabilizes PERP at the PM and induces its increasing co-localization with SERCA2b at ER–PM junctions. The findings highlight a novel crosstalk between pro-survival autophagy and pro-death apoptosis pathways and identify, for the first time, accumulation of an apoptosis effector to ER–PM junctions in response to ER stress.
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Affiliation(s)
- Samantha J McDonnell
- 1Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX UK
| | - David G Spiller
- 2Systems Microscopy Centre, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT UK
| | - Michael R H White
- 3School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT UK
| | - Ian A Prior
- 4Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, L69 3BX UK
| | - Luminita Paraoan
- 1Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX UK
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6
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Szymański J, Janikiewicz J, Michalska B, Patalas-Krawczyk P, Perrone M, Ziółkowski W, Duszyński J, Pinton P, Dobrzyń A, Więckowski MR. Interaction of Mitochondria with the Endoplasmic Reticulum and Plasma Membrane in Calcium Homeostasis, Lipid Trafficking and Mitochondrial Structure. Int J Mol Sci 2017; 18:ijms18071576. [PMID: 28726733 PMCID: PMC5536064 DOI: 10.3390/ijms18071576] [Citation(s) in RCA: 149] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Revised: 07/10/2017] [Accepted: 07/13/2017] [Indexed: 12/12/2022] Open
Abstract
Studying organelles in isolation has been proven to be indispensable for deciphering the underlying mechanisms of molecular cell biology. However, observing organelles in intact cells with the use of microscopic techniques reveals a new set of different junctions and contact sites between them that contribute to the control and regulation of various cellular processes, such as calcium and lipid exchange or structural reorganization of the mitochondrial network. In recent years, many studies focused their attention on the structure and function of contacts between mitochondria and other organelles. From these studies, findings emerged showing that these contacts are involved in various processes, such as lipid synthesis and trafficking, modulation of mitochondrial morphology, endoplasmic reticulum (ER) stress, apoptosis, autophagy, inflammation and Ca2+ handling. In this review, we focused on the physical interactions of mitochondria with the endoplasmic reticulum and plasma membrane and summarized present knowledge regarding the role of mitochondria-associated membranes in calcium homeostasis and lipid metabolism.
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Affiliation(s)
- Jędrzej Szymański
- Department of Biochemistry, Nencki Institute of Experimental Biology, Pasteur 3, 02-093 Warsaw, Poland.
| | - Justyna Janikiewicz
- Department of Biochemistry, Nencki Institute of Experimental Biology, Pasteur 3, 02-093 Warsaw, Poland.
| | - Bernadeta Michalska
- Department of Biochemistry, Nencki Institute of Experimental Biology, Pasteur 3, 02-093 Warsaw, Poland.
| | - Paulina Patalas-Krawczyk
- Department of Biochemistry, Nencki Institute of Experimental Biology, Pasteur 3, 02-093 Warsaw, Poland.
| | - Mariasole Perrone
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, 44121 Ferrara, Italy.
| | - Wiesław Ziółkowski
- Department of Bioenergetics and Nutrition, Gdańsk University of Physical Education and Sport, 80-336 Gdańsk, Poland.
| | - Jerzy Duszyński
- Department of Biochemistry, Nencki Institute of Experimental Biology, Pasteur 3, 02-093 Warsaw, Poland.
| | - Paolo Pinton
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, 44121 Ferrara, Italy.
| | - Agnieszka Dobrzyń
- Department of Biochemistry, Nencki Institute of Experimental Biology, Pasteur 3, 02-093 Warsaw, Poland.
| | - Mariusz R Więckowski
- Department of Biochemistry, Nencki Institute of Experimental Biology, Pasteur 3, 02-093 Warsaw, Poland.
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7
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Chemaly ER, Troncone L, Lebeche D. SERCA control of cell death and survival. Cell Calcium 2017; 69:46-61. [PMID: 28747251 DOI: 10.1016/j.ceca.2017.07.001] [Citation(s) in RCA: 132] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 07/03/2017] [Accepted: 07/03/2017] [Indexed: 12/31/2022]
Abstract
Intracellular calcium (Ca2+) is a critical coordinator of various aspects of cellular physiology. It is increasingly apparent that changes in cellular Ca2+ dynamics contribute to the regulation of normal and pathological signal transduction that controls cell growth and survival. Aberrant perturbations in Ca2+ homeostasis have been implicated in a range of pathological conditions, such as cardiovascular diseases, diabetes, tumorigenesis and steatosis hepatitis. Intracellular Ca2+ concentrations are therefore tightly regulated by a number of Ca2+ handling enzymes, proteins, channels and transporters located in the plasma membrane and in Ca2+ storage organelles, which work in concert to fine tune a temporally and spatially precise Ca2+ signal. Chief amongst them is the sarco/endoplasmic reticulum (SR/ER) Ca2+ ATPase pump (SERCA) which actively re-accumulates released Ca2+ back into the SR/ER, therefore maintaining Ca2+ homeostasis. There are at least 14 different SERCA isoforms encoded by three ATP2A1-3 genes whose expressions are species- and tissue-specific. Altered SERCA expression and activity results in cellular malignancy and induction of ER stress and ER stress-associated apoptosis. The role of SERCA misregulation in the control of apoptosis in various cell types and disease setting with prospective therapeutic implications is the focus of this review. Ca2+ is a double edge sword for both life as well as death, and current experimental evidence supports a model in which Ca2+ homeostasis and SERCA activity represent a nodal point that controls cell survival. Pharmacological or genetic targeting of this axis constitutes an incredible therapeutic potential to treat different diseases sharing similar biological disorders.
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Affiliation(s)
- Elie R Chemaly
- Division of Nephrology and Hypertension, Department of Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - Luca Troncone
- Cardiovascular Research Institute, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Djamel Lebeche
- Cardiovascular Research Institute, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA; Diabetes, Obesity and Metabolism Institute, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA; Graduate School of Biological Sciences, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
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8
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Ahmad S, Ahmad A, Hendry-Hofer TB, Loader JE, Claycomb WC, Mozziconacci O, Schöneich C, Reisdorph N, Powell RL, Chandler JD, Day BJ, Veress LA, White CW. Sarcoendoplasmic reticulum Ca(2+) ATPase. A critical target in chlorine inhalation-induced cardiotoxicity. Am J Respir Cell Mol Biol 2016; 52:492-502. [PMID: 25188881 DOI: 10.1165/rcmb.2014-0005oc] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Autopsy specimens from human victims or experimental animals that die due to acute chlorine gas exposure present features of cardiovascular pathology. We demonstrate acute chlorine inhalation-induced reduction in heart rate and oxygen saturation in rats. Chlorine inhalation elevated chlorine reactants, such as chlorotyrosine and chloramine, in blood plasma. Using heart tissue and primary cardiomyocytes, we demonstrated that acute high-concentration chlorine exposure in vivo (500 ppm for 30 min) caused decreased total ATP content and loss of sarcoendoplasmic reticulum calcium ATPase (SERCA) activity. Loss of SERCA activity was attributed to chlorination of tyrosine residues and oxidation of an important cysteine residue, cysteine-674, in SERCA, as demonstrated by immunoblots and mass spectrometry. Using cardiomyocytes, we found that chlorine-induced cell death and damage to SERCA could be decreased by thiocyanate, an important biological antioxidant, and by genetic SERCA2 overexpression. We also investigated a U.S. Food and Drug Administration-approved drug, ranolazine, used in treatment of cardiac diseases, and previously shown to stabilize SERCA in animal models of ischemia-reperfusion. Pretreatment with ranolazine or istaroxime, another SERCA activator, prevented chlorine-induced cardiomyocyte death. Further investigation of responsible mechanisms showed that ranolazine- and istaroxime-treated cells preserved mitochondrial membrane potential and ATP after chlorine exposure. Thus, these studies demonstrate a novel critical target for chlorine in the heart and identify potentially useful therapies to mitigate toxicity of acute chlorine exposure.
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Affiliation(s)
- Shama Ahmad
- 1 Pediatric Airway Research Center, Department of Pediatrics, University of Colorado, Denver, Aurora, Colorado
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9
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Bonora M, Giorgi C, Pinton P. Novel frontiers in calcium signaling: A possible target for chemotherapy. Pharmacol Res 2015; 99:82-5. [DOI: 10.1016/j.phrs.2015.05.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2015] [Accepted: 05/18/2015] [Indexed: 10/23/2022]
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10
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Selli C, Erac Y, Tosun M. Simultaneous measurement of cytosolic and mitochondrial calcium levels: Observations in TRPC1-silenced hepatocellular carcinoma cells. J Pharmacol Toxicol Methods 2015; 72:29-34. [DOI: 10.1016/j.vascn.2014.12.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 12/15/2014] [Accepted: 12/15/2014] [Indexed: 01/09/2023]
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11
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Schöneich C, Dremina E, Galeva N, Sharov V. Apoptosis in differentiating C2C12 muscle cells selectively targets Bcl-2-deficient myotubes. Apoptosis 2014; 19:42-57. [PMID: 24129924 DOI: 10.1007/s10495-013-0922-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Muscle cell apoptosis accompanies normal muscle development and regeneration, as well as degenerative diseases and aging. C2C12 murine myoblast cells represent a common model to study muscle differentiation. Though it was already shown that myogenic differentiation of C2C12 cells is accompanied by enhanced apoptosis in a fraction of cells, either the cell population sensitive to apoptosis or regulatory mechanisms for the apoptotic response are unclear so far. In the current study we characterize apoptotic phenotypes of different types of C2C12 cells at all stages of differentiation, and report here that myotubes of differentiated C2C12 cells with low levels of anti-apoptotic Bcl-2 expression are particularly vulnerable to apoptosis even though they are displaying low levels of pro-apoptotic proteins Bax, Bak and Bad. In contrast, reserve cells exhibit higher levels of Bcl-2 and high resistance to apoptosis. The transfection of proliferating myoblasts with Bcl-2 prior to differentiation did not protect against spontaneous apoptosis accompanying differentiation of C2C12 cells but led to Bcl-2 overexpression in myotubes and to significant protection from apoptotic cell loss caused by exposure to hydrogen peroxide. Overall, our data advocate for a Bcl-2-dependent mechanism of apoptosis in differentiated muscle cells. However, downstream processes for spontaneous and hydrogen peroxide induced apoptosis are not completely similar. Apoptosis in differentiating myoblasts and myotubes is regulated not through interaction of Bcl-2 with pro-apoptotic Bcl-2 family proteins such as Bax, Bak, and Bad.
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12
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Erac Y, Selli C, Filik P, Tosun M. Effects of passage number on proliferation and store-operated calcium entry in A7r5 vascular smooth muscle cells. J Pharmacol Toxicol Methods 2014; 70:1-5. [DOI: 10.1016/j.vascn.2014.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 02/13/2014] [Accepted: 03/02/2014] [Indexed: 10/25/2022]
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13
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Marchi S, Giorgi C, Oparka M, Duszynski J, Wieckowski MR, Pinton P. Oncogenic and oncosuppressive signal transduction at mitochondria-associated endoplasmic reticulum membranes. Mol Cell Oncol 2014; 1:e956469. [PMID: 27308328 PMCID: PMC4905193 DOI: 10.4161/23723548.2014.956469] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Revised: 07/14/2014] [Accepted: 07/17/2014] [Indexed: 12/22/2022]
Abstract
The different mechanisms employed by proto-oncogenes and tumor suppressors to regulate cell death pathways are strictly linked to their localization. In addition to the canonical control of apoptosis at a transcriptional/nuclear level, intracellular zones are emerging as pivotal sites for the activities of several proapoptotic and antiapoptotic factors. Here, we review the function of the endoplasmic reticulum-mitochondria interface as a primary platform for decoding danger signals as well as a structural accommodation for several regulator or effector proteins.
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Affiliation(s)
- Saverio Marchi
- Department of Morphology; Surgery and Experimental Medicine; Section of Pathology; Oncology and Experimental Biology and LTTA Center; University of Ferrara; Ferrara, Italy
| | - Carlotta Giorgi
- Department of Morphology; Surgery and Experimental Medicine; Section of Pathology; Oncology and Experimental Biology and LTTA Center; University of Ferrara; Ferrara, Italy
| | - Monika Oparka
- Department of Biochemistry; Nencki Institute of Experimental Biology; Warsaw, Poland
| | - Jerzy Duszynski
- Department of Biochemistry; Nencki Institute of Experimental Biology; Warsaw, Poland
| | - Mariusz R Wieckowski
- Department of Biochemistry; Nencki Institute of Experimental Biology; Warsaw, Poland
| | - Paolo Pinton
- Department of Morphology; Surgery and Experimental Medicine; Section of Pathology; Oncology and Experimental Biology and LTTA Center; University of Ferrara; Ferrara, Italy
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14
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Giorgi C, Baldassari F, Bononi A, Bonora M, De Marchi E, Marchi S, Missiroli S, Patergnani S, Rimessi A, Suski JM, Wieckowski MR, Pinton P. Mitochondrial Ca(2+) and apoptosis. Cell Calcium 2012; 52:36-43. [PMID: 22480931 PMCID: PMC3396846 DOI: 10.1016/j.ceca.2012.02.008] [Citation(s) in RCA: 337] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 02/23/2012] [Accepted: 02/24/2012] [Indexed: 01/13/2023]
Abstract
Mitochondria are key decoding stations of the apoptotic process. In support of this view, a large body of experimental evidence has unambiguously revealed that, in addition to the well-established function of producing most of the cellular ATP, mitochondria play a fundamental role in triggering apoptotic cell death. Various apoptotic stimuli cause the release of specific mitochondrial pro-apoptotic factors into the cytosol. The molecular mechanism of this release is still controversial, but there is no doubt that mitochondrial calcium (Ca(2+)) overload is one of the pro-apoptotic ways to induce the swelling of mitochondria, with perturbation or rupture of the outer membrane, and in turn the release of mitochondrial apoptotic factors into the cytosol. Here, we review as different proteins that participate in mitochondrial Ca(2+) homeostasis and in turn modulate the effectiveness of Ca(2+)-dependent apoptotic stimuli. Strikingly, the final outcome at the cellular level is similar, albeit through completely different molecular mechanisms: a reduced mitochondrial Ca(2+) overload upon pro-apoptotic stimuli that dramatically blunts the apoptotic response.
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Affiliation(s)
- Carlotta Giorgi
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, Interdisciplinary Center for the Study of Inflammation (ICSI), Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
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15
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Perazzo JC, Tallis S, Delfante A, Souto PA, Lemberg A, Eizayaga FX, Romay S. Hepatic encephalopathy: An approach to its multiple pathophysiological features. World J Hepatol 2012; 4:50-65. [PMID: 22489256 PMCID: PMC3321490 DOI: 10.4254/wjh.v4.i3.50] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2011] [Revised: 11/19/2011] [Accepted: 02/24/2012] [Indexed: 02/06/2023] Open
Abstract
Hepatic encephalopathy (HE) is a neuropsychiatric complex syndrome, ranging from subtle behavioral abnormalities to deep coma and death. Hepatic encephalopathy emerges as the major complication of acute or chronic liver failure. Multiplicity of factors are involved in its pathophysiology, such as central and neuromuscular neurotransmission disorder, alterations in sleep patterns and cognition, changes in energy metabolism leading to cell injury, an oxidative/nitrosative state and a neuroinflammatory condition. Moreover, in acute HE, a condition of imminent threat of death is present due to a deleterious astrocyte swelling. In chronic HE, changes in calcium signaling, mitochondrial membrane potential and long term potential expression, N-methyl-D-aspartate-cGMP and peripheral benzodiazepine receptors alterations, and changes in the mRNA and protein expression and redistribution in the cerebral blood flow can be observed. The main molecule indicated as responsible for all these changes in HE is ammonia. There is no doubt that ammonia, a neurotoxic molecule, triggers or at least facilitates most of these changes. Ammonia plasma levels are increased two- to three-fold in patients with mild to moderate cirrhotic HE and up to ten-fold in patients with acute liver failure. Hepatic and inter-organ trafficking of ammonia and its metabolite, glutamine (GLN), lead to hyperammonemic conditions. Removal of hepatic ammonia is a differentiated work that includes the hepatocyte, through the urea cycle, converting ammonia into GLN via glutamine synthetase. Under pathological conditions, such as liver damage or liver blood by-pass, the ammonia plasma level starts to rise and the risk of HE developing is high. Knowledge of the pathophysiology of HE is rapidly expanding and identification of focally localized triggers has led the development of new possibilities for HE to be considered. This editorial will focus on issues where, to the best of our knowledge, more research is needed in order to clarify, at least partially, controversial topics.
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Affiliation(s)
- Juan Carlos Perazzo
- Juan Carlos Perazzo, Silvina Tallis, Amalia Delfante, Pablo Andrés Souto, Abraham Lemberg, Francisco Xavier Eizayaga, Salvador Romay, Laboratory of Portal Hypertension and Hepatic Encephalopathy, Pathophysiology, School of Pharmacy and Biochemistry, University of Buenos Aires, Junin 950, CP 1113, Buenos Aires, Argentina
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16
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Refined Qingkailing Protects MCAO Mice from Endoplasmic Reticulum Stress-Induced Apoptosis with a Broad Time Window. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2012; 2012:567872. [PMID: 22536287 PMCID: PMC3320064 DOI: 10.1155/2012/567872] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2011] [Revised: 01/02/2012] [Accepted: 01/03/2012] [Indexed: 11/18/2022]
Abstract
In the current study, we are investigating effect of refined QKL on ischemia-reperfusion-induced brain injury in mice. Methods. Mice were employed to induce ischemia-reperfusion injury of brain by middle cerebral artery occlusion (MCAO). RQKL solution was administered with different doses (0, 1.5, 3, and 6 mL/kg body weight) at the same time of onset of ischemia, and with the dose of 1.5 mL/kg at different time points (0, 1.5, 3, 6, and 9 h after MCAO). Neurological function and brain infarction were examined and cell apoptosis and ROS at prefrontal cortex were evaluated 24 h after MCAO, and western blot and intracellular calcium were also researched, respectively. Results. RQKL of all doses can improve neurological function and decrease brain infarction, and it performed significant effect in 0, 1.5, 3, and 6 h groups. Moreover, RQKL was able to reduce apoptotic process by reduction of caspase-3 expression, or restraint of eIF2a phosphorylation and caspase-12 activation. It was also able to reduce ROS and modulate intracellular calcium in the brain. Conclusion. RQKL can prevent ischemic-induced brain injury with a time window of 6 h, and its mechanism might be related to suppress ER stress-mediated apoptotic signaling.
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17
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Bollo M, Paredes RM, Holstein D, Zheleznova N, Camacho P, Lechleiter JD. Calcineurin interacts with PERK and dephosphorylates calnexin to relieve ER stress in mammals and frogs. PLoS One 2010; 5:e11925. [PMID: 20700529 PMCID: PMC2916823 DOI: 10.1371/journal.pone.0011925] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2010] [Accepted: 06/17/2010] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The accumulation of misfolded proteins within the endoplasmic reticulum (ER) triggers a cellular process known as the Unfolded Protein Response (UPR). One of the earliest responses is the attenuation of protein translation. Little is known about the role that Ca2+ mobilization plays in the early UPR. Work from our group has shown that cytosolic phosphorylation of calnexin (CLNX) controls Ca2+ uptake into the ER via the sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) 2b. METHODOLOGY/PRINCIPAL FINDINGS Here, we demonstrate that calcineurin (CN), a Ca2+ dependent phosphatase, associates with the (PKR)-like ER kinase (PERK), and promotes PERK auto-phosphorylation. This association, in turn, increases the phosphorylation level of eukaryotic initiation factor-2 alpha (eIF2-alpha) and attenuates protein translation. Data supporting these conclusions were obtained from co-immunoprecipitations, pull-down assays, in-vitro kinase assays, siRNA treatments and [35S]-methionine incorporation measurements. The interaction of CN with PERK was facilitated at elevated cytosolic Ca2+ concentrations and involved the cytosolic domain of PERK. CN levels were rapidly increased by ER stressors, which could be blocked by siRNA treatments for CN-Aalpha in cultured astrocytes. Downregulation of CN blocked subsequent ER-stress-induced increases in phosphorylated elF2-alpha. CN knockdown in Xenopus oocytes predisposed them to induction of apoptosis. We also found that CLNX was dephosphorylated by CN when Ca2+ increased. These data were obtained from [gamma32P]-CLNX immunoprecipitations and Ca2+ imaging measurements. CLNX was dephosphorylated when Xenopus oocytes were treated with ER stressors. Dephosphorylation was pharmacologically blocked by treatment with CN inhibitors. Finally, evidence is presented that PERK phosphorylates CN-A at low resting levels of Ca2+. We further show that phosphorylated CN-A exhibits decreased phosphatase activity, consistent with this regulatory mechanism being shut down as ER homeostasis is re-established. CONCLUSIONS/SIGNIFICANCE Our data suggest two new complementary roles for CN in the regulation of the early UPR. First, CN binding to PERK enhances inhibition of protein translation to allow the cell time to recover. The induction of the early UPR, as indicated by increased P-elF2alpha, is critically dependent on a translational increase in CN-Aalpha. Second, CN dephosphorylates CLNX and likely removes inhibition of SERCA2b activity, which would aid the rapid restoration of ER Ca2+ homeostasis.
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Affiliation(s)
- Mariana Bollo
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC CONICET), Córdoba, Argentina
| | - R. Madelaine Paredes
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Deborah Holstein
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Nadezhda Zheleznova
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Patricia Camacho
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - James D. Lechleiter
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- * E-mail:
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18
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Rizzuto R, Marchi S, Bonora M, Aguiari P, Bononi A, De Stefani D, Giorgi C, Leo S, Rimessi A, Siviero R, Zecchini E, Pinton P. Ca(2+) transfer from the ER to mitochondria: when, how and why. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1787:1342-51. [PMID: 19341702 PMCID: PMC2730423 DOI: 10.1016/j.bbabio.2009.03.015] [Citation(s) in RCA: 342] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 03/21/2009] [Accepted: 03/24/2009] [Indexed: 10/25/2022]
Abstract
The heterogenous subcellular distribution of a wide array of channels, pumps and exchangers allows extracellular stimuli to induce increases in cytoplasmic Ca(2+) concentration ([Ca(2+)]c) with highly defined spatial and temporal patterns, that in turn induce specific cellular responses (e.g. contraction, secretion, proliferation or cell death). In this extreme complexity, the role of mitochondria was considered marginal, till the direct measurement with targeted indicators allowed to appreciate that rapid and large increases of the [Ca(2+)] in the mitochondrial matrix ([Ca(2+)]m) invariably follow the cytosolic rises. Given the low affinity of the mitochondrial Ca(2+) transporters, the close proximity to the endoplasmic reticulum (ER) Ca(2+)-releasing channels was shown to be responsible for the prompt responsiveness of mitochondria. In this review, we will summarize the current knowledge of: i) the mitochondrial and ER Ca(2+) channels mediating the ion transfer, ii) the structural and molecular foundations of the signaling contacts between the two organelles, iii) the functional consequences of the [Ca(2+)]m increases, and iv) the effects of oncogene-mediated signals on mitochondrial Ca(2+) homeostasis. Despite the rapid progress carried out in the latest years, a deeper molecular understanding is still needed to unlock the secrets of Ca(2+) signaling machinery.
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Affiliation(s)
- Rosario Rizzuto
- Dept. Biomedical Sciences, University of Padua, Via Colombo 3, Padua 35121, Italy.
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19
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de Mattia F, Gubser C, van Dommelen MMT, Visch HJ, Distelmaier F, Postigo A, Luyten T, Parys JB, de Smedt H, Smith GL, Willems PHGM, van Kuppeveld FJM. Human Golgi antiapoptotic protein modulates intracellular calcium fluxes. Mol Biol Cell 2009; 20:3638-45. [PMID: 19553469 DOI: 10.1091/mbc.e09-05-0385] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Golgi antiapoptotic protein (GAAP) is a novel regulator of cell death that is highly conserved in eukaryotes and present in some poxviruses, but its molecular mechanism is unknown. Given that alterations in intracellular Ca(2+) homeostasis play an important role in determining cell sensitivity to apoptosis, we investigated if GAAP affected Ca(2+) signaling. Overexpression of human (h)-GAAP suppressed staurosporine-induced, capacitative Ca(2+) influx from the extracellular space. In addition, it reduced histamine-induced Ca(2+) release from intracellular stores through inositol trisphosphate receptors. h-GAAP not only decreased the magnitude of the histamine-induced Ca(2+) fluxes from stores to cytosol and mitochondrial matrices, but it also reduced the induction and frequency of oscillatory changes in cytosolic Ca(2+). Overexpression of h-GAAP lowered the Ca(2+) content of the intracellular stores and decreased the efficacy of IP(3), providing possible explanations for the observed results. Opposite effects were obtained when h-GAAP was knocked down by siRNA. Thus, our data demonstrate that h-GAAP modulates intracellular Ca(2+) fluxes induced by both physiological and apoptotic stimuli.
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Affiliation(s)
- Fabrizio de Mattia
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, The Netherlands
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20
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Abstract
There is a growing consensus that the various forms of cell death (necrosis, apoptosis and autophagy) are not separated by strict boundaries, but rather share molecular effectors and signaling routes. Among the latter, a clear role is played by calcium (Ca(2+)), the ubiquitous second messenger involved in the control of a broad variety of physiological events. Fine tuning of intracellular Ca(2+) homeostasis by anti- and proapoptotic proteins shapes the Ca(2+) signal to which mitochondria and other cellular effectors are exposed, and hence the efficiency of various cell death inducers. Here, we will review: (i) the evidence linking calcium homeostasis to the regulation of apoptotic, and more recently autophagic cell death, (ii) the discussion of mitochondria as a critical, although not unique checkpoint and (iii) the molecular and functional elucidation of ER/mitochondria contacts, corresponding to the mitochondria-associated membrane (MAM) subfraction and proposed to be a specialized signaling microdomain.
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21
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Vafiadaki E, Arvanitis DA, Pagakis SN, Papalouka V, Sanoudou D, Kontrogianni-Konstantopoulos A, Kranias EG. The anti-apoptotic protein HAX-1 interacts with SERCA2 and regulates its protein levels to promote cell survival. Mol Biol Cell 2008; 20:306-18. [PMID: 18971376 DOI: 10.1091/mbc.e08-06-0587] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Cardiac contractility is regulated through the activity of various key Ca(2+)-handling proteins. The sarco(endo)plasmic reticulum (SR) Ca(2+) transport ATPase (SERCA2a) and its inhibitor phospholamban (PLN) control the uptake of Ca(2+) by SR membranes during relaxation. Recently, the antiapoptotic HS-1-associated protein X-1 (HAX-1) was identified as a binding partner of PLN, and this interaction was postulated to regulate cell apoptosis. In the current study, we determined that HAX-1 can also bind to SERCA2. Deletion mapping analysis demonstrated that amino acid residues 575-594 of SERCA2's nucleotide binding domain are required for its interaction with the C-terminal domain of HAX-1, containing amino acids 203-245. In transiently cotransfected human embryonic kidney 293 cells, recombinant SERCA2 was specifically targeted to the ER, whereas HAX-1 selectively concentrated at mitochondria. On triple transfections with PLN, however, HAX-1 massively translocated to the ER membranes, where it codistributed with PLN and SERCA2. Overexpression of SERCA2 abrogated the protective effects of HAX-1 on cell survival, after hypoxia/reoxygenation or thapsigargin treatment. Importantly, HAX-1 overexpression was associated with down-regulation of SERCA2 expression levels, resulting in significant reduction of apparent ER Ca(2+) levels. These findings suggest that HAX-1 may promote cell survival through modulation of SERCA2 protein levels and thus ER Ca(2+) stores.
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Affiliation(s)
- Elizabeth Vafiadaki
- Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Greece
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22
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Rimessi A, Giorgi C, Pinton P, Rizzuto R. The versatility of mitochondrial calcium signals: from stimulation of cell metabolism to induction of cell death. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:808-16. [PMID: 18573473 DOI: 10.1016/j.bbabio.2008.05.449] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Revised: 05/22/2008] [Accepted: 05/23/2008] [Indexed: 10/21/2022]
Abstract
Both the contribution of mitochondria to intracellular calcium (Ca(2+)) signalling and the role of mitochondrial Ca(2+) uptake in shaping the cytoplasmic response and controlling mitochondrial function are areas of intense investigation. These studies rely on the appropriate use of emerging techniques coupled with judicious data interpretation to a large extent. The development of targeted probes based on the molecular engineering of luminescent proteins has allowed the specific measurement of Ca(2+) concentration ([Ca(2+)]) and adenosine trisphosphate concentration ([ATP]) in intracellular organelles or cytoplasmic subdomains. This approach has given novel information on different aspects of mitochondrial homeostasis.
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Affiliation(s)
- Alessandro Rimessi
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, Interdisciplinary Center for the Study of Inflammation and Emilia Romagna Laboratory BioPharmaNet, University of Ferrara, Ferrara, Italy
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23
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Ulusu NN, Tandoğan B, Tanyel FC. Sarco(endo)plasmic reticulum and plasmalemmal Ca(2+)-ATPase activities in cremaster muscles and sacs differ according to the associated inguinal pathology. Cell Biochem Funct 2007; 25:515-9. [PMID: 16933204 DOI: 10.1002/cbf.1341] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) and plasmalemmal Ca(2+)-ATPase (PMCA) activities in cremaster muscles and sacs, which have been subjected to different autonomic tonuses, were determined and compared. Samples of cremaster muscles and sacs associated with male or female inguinal hernia, hydrocele or undescended testis were obtained from children during operations and activities of SERCA and PMCA were determined. While highest SERCA and PMCA activities were encountered among cremaster muscles and sacs associated with undescended testis, least activities were encountered among structures associated with hydrocele. The alterations in SERCA and PMCA activities in cremaster muscles associated with undescended testis appear to reflect the attempts at maintaining the levels of cytosolic calcium. Despite similar total calcium contents, lower SERCA and PMCA activities were found in sacs associated with hydrocele compared to those associated with undescended testis suggest a difference among the levels of cytosolic calcium.
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Affiliation(s)
- N N Ulusu
- Department of Biochemistry, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
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24
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Foradori CD, Werner SB, Sandau US, Clapp TR, Handa RJ. Activation of the androgen receptor alters the intracellular calcium response to glutamate in primary hippocampal neurons and modulates sarco/endoplasmic reticulum calcium ATPase 2 transcription. Neuroscience 2007; 149:155-64. [PMID: 17870249 DOI: 10.1016/j.neuroscience.2007.06.054] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Revised: 05/28/2007] [Accepted: 06/16/2007] [Indexed: 10/23/2022]
Abstract
Androgens have been shown to have a number of effects on hippocampal function. Although androgen receptors (AR) are found at high levels in hippocampal neurons, the intracellular mechanisms responsible for androgen's actions are unknown. If androgens were capable of altering internal calcium concentration ([Ca(2+)](i)), they could influence a variety of intracellular signaling pathways, maintain neuronal homeostasis and Ca(2+) induced excitotoxicity. In the present study, calcium imaging was used to measure the [Ca(2+)](i) in rat primary hippocampal neurons treated with either the AR agonist dihydrotestosterone (DHT), DHT+flutamide (AR antagonist), flutamide alone, or vehicle for 24 h and subsequently presented with an excitatory glutamate stimulus. In the absence of glutamate stimulation, DHT treatment caused a significant upward shift in baseline [Ca(2+)](i) when compared with neurons from all other groups. Glutamate had a greater effect on [Ca(2+)](i) in DHT-treated neurons and DHT-treated neurons returned to baseline levels significantly faster than all other groups. Cyclopiazonic acid, an inhibitor of sarco/endoplasmic reticulum calcium ATPase (SERCA) had a larger response in DHT-treated neurons compared with controls, suggesting increased Ca(2+) stores in DHT-treated neurons. In all cases the effects of DHT were blocked by treatment with flutamide indicating an AR-mediated mechanism. To determine a possible mechanism by which AR activation could be influencing [Ca(2+)](i), SERCA2 mRNA levels were measured in primary hippocampal neurons. SERCA2 is inserted into the endoplasmic reticulum (ER) membrane and functions to rapidly pump [Ca(2+)](i) into the ER. Following treatment of primary hippocampal neurons with DHT, SERCA2 mRNA was increased, an effect that was blocked in the presence of flutamide. Taken together these results indicate that DHT, working through AR, causes an up-regulation of SERCA2, which increases the sequestering of [Ca(2+)](i) in the endoplasmic reticulum of hippocampal neurons. Such changes may allow the neurons to respond more robustly to a stimulus and recover more quickly following a highly stimulatory challenge.
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Affiliation(s)
- C D Foradori
- Department of Biomedical Sciences, Anatomy and Neurobiology Section, Colorado State University, Fort Collins, CO 80523, USA.
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25
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Ihara-Ohori Y, Nagano M, Muto S, Uchimiya H, Kawai-Yamada M. Cell death suppressor Arabidopsis bax inhibitor-1 is associated with calmodulin binding and ion homeostasis. PLANT PHYSIOLOGY 2007; 143:650-60. [PMID: 17142482 PMCID: PMC1803746 DOI: 10.1104/pp.106.090878] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Cell death suppressor Bax inhibitor-1 (BI-1), an endoplasmic reticulum membrane protein, exists in a wide range of organisms. The split-ubiquitin system, overlay assay, and bimolecular fluorescence complementation analysis demonstrated that Arabidopsis (Arabidopsis thaliana) BI-1 (AtBI-1) interacted with calmodulin in yeast (Saccharomyces cerevisiae) and in plant cells. Furthermore, AtBI-1 failed to rescue yeast mutants lacking Ca2+ ATPase (Pmr1 or Spf1) from Bax-induced cell death. Pmr1 and Spf1, p-type ATPases localized at the inner membrane, are believed to be involved in transmembrane movement of calcium ions in yeast. Thus, the presence of intact Ca2+ ATPases was essential for AtBI-1-mediated cell death suppression in yeast. To investigate the effect of AtBI-1 on calcium homeostasis, we evaluated sensitivity against cyclopiazonic acid (CPA), an inhibitor of sarcoplasmic/endoplasmic reticulum Ca2+ ATPase in AtBI-1-overexpressing or knock-down transgenic Arabidopsis plants. These plants demonstrated altered CPA or ion stress sensitivity. Furthermore, AtBI-1-overexpressing cells demonstrated an attenuated rise in cytosolic calcium following CPA or H2O2 treatment, suggesting that AtBI-1 affects ion homeostasis in plant cell death regulation.
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Affiliation(s)
- Yuri Ihara-Ohori
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
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26
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Pinton P, Rizzuto R. Bcl-2 and Ca2+ homeostasis in the endoplasmic reticulum. Cell Death Differ 2006; 13:1409-18. [PMID: 16729032 DOI: 10.1038/sj.cdd.4401960] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Recent data have revealed an unexpected role of Bcl-2 in modulating the steady-state levels and agonist-dependent fluxes of Ca(2+) ions. Direct monitoring of endoplasmic reticulum (ER) Ca(2+) concentration with recombinant probes reveals a lower state of filling in Bcl-2-overexpressing cells and a higher leak rate from the organelle. The broader set of indirect data using cytosolic probes reveals a more complex scenario, as in many cases no difference was detected in the Ca(2+) content of the intracellular pools. At the same time, Ca(2+) signals have been shown to affect important checkpoints of the apoptotic process, such as mitochondria, thus tuning the sensitivity of cells to various challenges. In this contribution, we will review (i) the data on the effect of Bcl-2 on [Ca(2+)](er), (ii) the functional significance of the Ca(2+)-signalling alteration and (iii) the current insight into the possible mechanisms of this effect.
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Affiliation(s)
- P Pinton
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, ER-GenTech laboratory and Interdisciplinary Center for the Study of Inflammation (ICSI), University of Ferrara, Italy
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27
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Chen X, Zhang X, Kubo H, Harris DM, Mills GD, Moyer J, Berretta R, Potts ST, Marsh JD, Houser SR. Ca
2+
Influx–Induced Sarcoplasmic Reticulum Ca
2+
Overload Causes Mitochondrial-Dependent Apoptosis in Ventricular Myocytes. Circ Res 2005; 97:1009-17. [PMID: 16210547 DOI: 10.1161/01.res.0000189270.72915.d1] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Increases in Ca
2+
influx through the L-type Ca
2+
channel (LTCC, Cav1.2) augment sarcoplasmic reticulum (SR) Ca
2+
loading and the amplitude of the cytosolic Ca
2+
transient to enhance cardiac myocyte contractility. Our hypothesis is that persistent increases in Ca
2+
influx through the LTCC cause apoptosis if the excessive influx results in SR Ca
2+
overload. Feline ventricular myocytes (VMs) in primary culture were infected with either an adenovirus (Ad) containing a rat Cav1.2 β
2a
subunit-green fluorescent protein (GFP) fusion gene (Adβ
2a
) to increase Ca
2+
influx or with AdGFP as a control. Significantly fewer β
2a
-VMs (21.4±5.6%) than GFP-VMs (99.6±1.7%) were viable at 96 hours. A fraction of β
2a
-VMs (20.8±1.8%) contracted spontaneously (SC-β
2a
-VMs), and viability was significantly correlated with the percentage of SC-β
2a
-VMs. Higher percentages of apoptotic nuclei, DNA laddering, and cytochrome C release were detected in β
2a
-VMs. This apoptosis was prevented with pancaspase or caspase-3 or caspase-9 inhibitors. L-type calcium current (I
Ca-L
) density was greater in β
2a
-VMs (23.4±2.8 pA/pF) than in GFP-VMs (7.6±1.6 pA/pF). SC-β
2a
-VMs had higher diastolic intracellular Ca
2+
(Indo-1 ratio: 1.1±0.1 versus 0.7±0.03,
P
<0.05) and systolic Ca
2+
transients (1.89±0.27 versus 0.80±0.08) than GFP-VMs. Inhibitors of Ca
2+
influx, SR Ca
2+
uptake and release, mitochondrial Ca
2+
uptake, mitochondrial permeation transition pore, calpain, and Bcl-2-associated X protein protected β
2a
-VMs from apoptosis. These results show that persistent increases in Ca
2+
influx through the I
Ca-L
enhance contractility but lead to apoptosis through a mitochondrial death pathway if SR Ca
2+
overload is induced.
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Affiliation(s)
- Xiongwen Chen
- Cardiovascular Research Center, Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, PA 19140, USA
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28
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Shi J, Parada LF, Kernie SG. Bax limits adult neural stem cell persistence through caspase and IP3 receptor activation. Cell Death Differ 2005; 12:1601-12. [PMID: 15947791 DOI: 10.1038/sj.cdd.4401676] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Neural stem cells in the mammalian brain persist and are functional well into adulthood. There is, however, little insight into mechanisms that control adult neural stem cell survival. Mice deficient in the proapoptotic molecule Bax exhibit increased numbers of multipotent progenitor cells in the adult subventricular zone. In vitro, these progenitors behave as neural stem cells and utilize Bax and caspase activation to direct cell death. We demonstrate that the predominate mechanism underlying caspase and Bax-mediated adult neural stem cell death lies in the modulation of calcium flux through interaction with the IP3 receptor.
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Affiliation(s)
- J Shi
- Department of Pediatrics, UT Southwestern Medical Center, 6000 Harry Hines Blvd, Dallas, TX 75390-9133, USA
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29
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Dremina E, Sharov V, Kumar K, Zaidi A, Michaelis E, Schöneich C. Anti-apoptotic protein Bcl-2 interacts with and destabilizes the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA). Biochem J 2004; 383:361-70. [PMID: 15245329 PMCID: PMC1134078 DOI: 10.1042/bj20040187] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2004] [Revised: 05/04/2004] [Accepted: 07/12/2004] [Indexed: 11/17/2022]
Abstract
The anti-apoptotic effect of Bcl-2 is well established, but the detailed mechanisms are unknown. In the present study, we show in vitro a direct interaction of Bcl-2 with the rat skeletal muscle SERCA (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase), leading to destabilization and inactivation of the protein. Recombinant human Bcl-2D21, a truncated form of Bcl-2 with a deletion of 21 residues at the C-terminal membrane-anchoring region, was expressed and affinity-purified as a glutathione S-transferase fusion protein. Bcl-2D21 co-immunoprecipitated and specifically interacted with SERCA in an in vitro-binding assay. The original level of Bcl-2 in sarcoplasmic reticulum vesicles was very low, i.e. hardly detectable by immunoblotting with specific antibodies. The addition of Bcl-2D21 to the sarcoplasmic reticulum resulted in the inhibition of the Ca2+-ATPase activity dependent on the Bcl-2D21/SERCA molar ratio and incubation time. A complete inactivation of SERCA was observed after 2.5 h of incubation at approx. 2:1 molar ratio of Bcl-2D21 to SERCA. In contrast, Bcl-2D21 did not significantly change the activity of the plasma-membrane Ca2+-ATPase. The redox state of the single Cys158 residue in Bcl-2D21 and the presence of GSH did not affect SERCA inhibition. The interaction of Bcl-2D21 with SERCA resulted in a conformational transition of SERCA, assessed through a Bcl-2-dependent increase in SERCA thiols available for the labelling with a fluorescent reagent. This partial unfolding of SERCA did not lead to a higher sensitivity of SERCA towards oxidative inactivation. Our results suggest that the direct interaction of Bcl-2 with SERCA may be involved in the regulation of apoptotic processes in vivo through modulation of cytoplasmic and/or endoplasmic reticulum calcium levels required for the execution of apoptosis.
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Key Words
- apoptosis
- bcl-2
- ca2+-atpase
- calcium
- sarcoplasmic/endoplasmic reticulum
- cam, calmodulin
- dtnb, 5,5′-dithiobis-(2-nitrobenzoic acid)
- er, endoplasmic reticulum
- esi-ms, electrospray ionization mass spectrometry
- gst, glutathione s-transferase
- maldi–tof, matrix-assisted laser-desorption ionization–time-of-flight
- nesi-ms/ms, nanoelectrospray ionization tandem mass spectrometry
- pmca, plasma-membrane ca2+-atpase
- serca, sarcoplasmic/endoplasmic-reticulum ca2+-atpase
- spm, synaptic plasma membranes
- sr, sarcoplasmic reticulum
- ste, tris-buffered saline
- tg, thapsigargin
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Affiliation(s)
- Elena S. Dremina
- *Department of Pharmaceutical Chemistry, University of Kansas, 2095 Constant Avenue, Lawrence, KS 66047, U.S.A
| | - Victor S. Sharov
- *Department of Pharmaceutical Chemistry, University of Kansas, 2095 Constant Avenue, Lawrence, KS 66047, U.S.A
| | - Keshava Kumar
- †Department of Pharmacology and Toxicology, University of Kansas, 2095 Constant Avenue, Lawrence, KS 66047, U.S.A
| | - Asma Zaidi
- †Department of Pharmacology and Toxicology, University of Kansas, 2095 Constant Avenue, Lawrence, KS 66047, U.S.A
| | - Elias K. Michaelis
- †Department of Pharmacology and Toxicology, University of Kansas, 2095 Constant Avenue, Lawrence, KS 66047, U.S.A
| | - Christian Schöneich
- *Department of Pharmaceutical Chemistry, University of Kansas, 2095 Constant Avenue, Lawrence, KS 66047, U.S.A
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Sun X, Zemel MB. Role of uncoupling protein 2 (UCP2) expression and 1alpha, 25-dihydroxyvitamin D3 in modulating adipocyte apoptosis. FASEB J 2004; 18:1430-2. [PMID: 15231722 DOI: 10.1096/fj.04-1971fje] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We previously found that 1alpha, 25-dihydroxyvitamin D3 [1alpha, 25-(OH)2-D3] modulates adipocyte lipid metabolism via a Ca2+-dependent mechanism and inhibits adipocyte UCP2 expression, indicating that the anti-obesity effects of dietary calcium are mediated by suppression of 1alpha, 25-(OH)2-D3 levels. However, because UCP2 reduces mitochondrial potential, we have evaluated the roles of UCP2, mitochondrial uncoupling, and 1alpha, 25-(OH)2-D3 in adipocyte apoptosis. Overexpressing UCP2 in 3T3-L1 cells induced marked reductions in mitochondrial potential (Deltapsi) and ATP production (P<0.01), increases in the expression of caspases (P<0.05), and a decrease in Bcl-2/Bax expression ratio (P<0.01). Physiological doses of 1alpha, 25-(OH)2-D3 (0.1-10 nM) restored mitochondrial Deltapsi in LI-UCP2 cells and protected against UCP2 overexpression-induced apoptosis (P<0.01), whereas a high dose (100 nM) stimulated apoptosis in 3T3-L1 and L1-UCP2 cells (P<0.05). 1alpha, 25-(OH)2-D3 stimulated cytosolic Ca2+ dose-dependently in both 3T3-L1 and L1-UCP2 cells. However, physiological doses suppressed mitochondrial Ca2+ levels by approximately 50% whereas the high dose increased mitochondrial Ca2+ by 25% (P<0.05); this explains stimulation of apoptosis by the high dose of 1alpha, 25-(OH)2-D3. Using high-calcium diets to suppress 1alpha, 25-(OH)2-D3 stimulated adipose tissue apoptosis in aP2 transgenic mice (P<0.01), suggesting that increasing dietary calcium stimulates adipose apoptosis and thereby further contributes to an anti-obesity effect of dietary calcium.
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Affiliation(s)
- Xiaocun Sun
- Department of Nutrition, University of Tennessee, Knoxville, TN 37996-1900, USA
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Szabadkai G, Rizzuto R. Participation of endoplasmic reticulum and mitochondrial calcium handling in apoptosis: more than just neighborhood? FEBS Lett 2004; 567:111-5. [PMID: 15165902 DOI: 10.1016/j.febslet.2004.04.059] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2004] [Accepted: 04/19/2004] [Indexed: 11/22/2022]
Abstract
Over the past few years, extensive progress has been made in elucidating the role of calcium in the signaling of apoptosis. This has led to the characterization of calcium's role in the induction of apoptosis and in the regulation of effector proteases. In this review, we attempt to summarize the current knowledge regarding a segment of these studies, the interaction between the endoplasmic reticulum (ER) and mitochondria. This interface has been shown to play a crucial role in transferring agonist induced Ca(2+) signals to mitochondria during physiological processes. Recent evidence, however, extended the role of this Ca(2+) transfer to apoptotic pathways, showing that modulation of mitochondrial Ca(2+) uptake from the ER side has a prominent role in modulating cellular fate.
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Affiliation(s)
- György Szabadkai
- Department of Experimental and Diagnostic Medicine, Interdisciplinary Center for the Study of Inflammation (ICSI), University of Ferrara, Via Borsari 46, 44100 Ferrara, Italy
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Chan SL, Fu W, Zhang P, Cheng A, Lee J, Kokame K, Mattson MP. Herp stabilizes neuronal Ca2+ homeostasis and mitochondrial function during endoplasmic reticulum stress. J Biol Chem 2004; 279:28733-43. [PMID: 15102845 DOI: 10.1074/jbc.m404272200] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In response to endoplasmic reticulum (ER) stress, cells launch homeostatic and protective responses, but can also activate cell death cascades. A 54 kDa integral ER membrane protein called Herp was identified as a stress-responsive protein in non-neuronal cells. We report that Herp is present in neurons in the developing and adult brain, and that it is regulated in neurons by ER stress; sublethal levels of ER stress increase Herp levels, whereas higher doses decrease Herp levels and induce apoptosis. The decrease in Herp protein levels following a lethal ER stress occurs prior to mitochondrial dysfunction and cell death, and is mediated by caspases which generate a 30-kDa proteolytic Herp fragment. Mutagenesis of the caspase cleavage site in Herp enhances its neuroprotective function during ER stress. While suppression of Herp induction by RNA interference sensitizes neural cells to apoptosis induced by ER stress, overexpression of Herp promotes survival by a mechanism involving stabilization of ER Ca(2+) levels, preservation of mitochondrial function and suppression of caspase 3 activation. ER stress-induced activation of JNK/c-Jun and caspase 12 are reduced by Herp, whereas induction of major ER chaperones is unaffected. Herp prevents ER Ca(2+) overload under conditions of ER stress and agonist-induced ER Ca(2+) release is attenuated by Herp suggesting a role for Herp in regulating neuronal Ca(2+) signaling. By stabilizing ER Ca(2+) homeostasis and mitochondrial functions, Herp serves a neuroprotective function under conditions of ER stress.
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Affiliation(s)
- Sic L Chan
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Gerontology Research Center, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA.
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Padar S, van Breemen C, Thomas DW, Uchizono JA, Livesey JC, Rahimian R. Differential regulation of calcium homeostasis in adenocarcinoma cell line A549 and its Taxol-resistant subclone. Br J Pharmacol 2004; 142:305-16. [PMID: 15066902 PMCID: PMC1574945 DOI: 10.1038/sj.bjp.0705755] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Drug resistance is a fundamental problem in cancer chemotherapy. Intracellular calcium concentration ([Ca2+](i)) may play a role in the development of chemoresistance. We investigated the regulatory role of [Ca2+](i) in Taxol resistance in the non-small-cell lung cancer cell line A549 and its chemoresistant subclone A549-T24. Measurement of cytosolic calcium ([Ca2+](c)) in single cells and cell populations revealed similar levels of basal calcium in the two cell lines. However, a reduced response to thapsigargin (a sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) inhibitor) in A549-T24 cells compared to the parent cell line suggested a lower ER Ca2+ content in these cells. mRNA expression of SERCA2b and SERCA3, major Ca2+ pumps involved in ER Ca2+ homeostasis, did not significantly differ between the two cell lines, as revealed by RT-PCR. An altered calcium influx pathway in the Taxol-resistant cell line was observed. Modulation of the ER calcium pools using CMC (4-chloro-m-cresol) and ATP revealed lower ryanodine receptor (RyR) and IP(3) receptor (IP(3)R)-sensitive Ca2+ stores in the chemoresistant cell line. Western blot and RT-PCR studies suggested that A549-T24 cells expressed higher levels of the antiapoptotic protein Bcl-2 and the calcium-binding protein sorcin, respectively, in comparison to the parent cell line. Both of these proteins have been previously implicated in chemoresistance, in part, due to their ability to modulate[Ca2+](i). These results suggest that altered intracellular calcium homeostasis may contribute to the Taxol-resistant phenotype.
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Affiliation(s)
- Shanthala Padar
- Department of Physiology & Pharmacology, Thomas J. Long School of Pharmacy and Health Sciences, University of the Pacific, Stockton, CA 95211, U.S.A
| | - Cornelis van Breemen
- BC Research Institute for Children's and Women's Health, University of British Columbia, Vancouver, Canada V6H3V4
| | - David W Thomas
- Department of Physiology & Pharmacology, Thomas J. Long School of Pharmacy and Health Sciences, University of the Pacific, Stockton, CA 95211, U.S.A
| | - James A Uchizono
- Department of Pharmaceutics and Medicinal Chemistry, Thomas J. Long School of Pharmacy and Health Sciences, University of the Pacific, Stockton, CA 95211, U.S.A
| | - John C Livesey
- Department of Physiology & Pharmacology, Thomas J. Long School of Pharmacy and Health Sciences, University of the Pacific, Stockton, CA 95211, U.S.A
| | - Roshanak Rahimian
- Department of Physiology & Pharmacology, Thomas J. Long School of Pharmacy and Health Sciences, University of the Pacific, Stockton, CA 95211, U.S.A
- Author for correspondence:
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Rizzuto R, Pinton P, Ferrari D, Chami M, Szabadkai G, Magalhães PJ, Di Virgilio F, Pozzan T. Calcium and apoptosis: facts and hypotheses. Oncogene 2003; 22:8619-27. [PMID: 14634623 DOI: 10.1038/sj.onc.1207105] [Citation(s) in RCA: 363] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Although longstanding experimental evidence has associated alterations of calcium homeostasis to cell death, only in the past few years the role of calcium in the signaling of apoptosis has been extensively investigated. In this review, we will summarize the current knowledge, focusing on (i) the effect of the proteins of the Bcl-2 family on ER Ca2+ levels, (ii) the action of the proteolytic enzymes of apoptosis on the Ca2+ signaling machinery, (iii) the ensuing alterations on the signaling patterns of extracellular stimuli, and (iv) the intracellular targets of 'apoptotic' Ca2+ signals, with special emphasis on the mitochondria and cytosolic Ca2+-dependent enzymes.
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Affiliation(s)
- Rosario Rizzuto
- Department of Experimental and Diagnostic Medicine and Center for the Study of Inflammation, University of Ferrara, Italy.
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35
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George CH, Higgs GV, Mackrill JJ, Lai FA. Dysregulated ryanodine receptors mediate cellular toxicity: restoration of normal phenotype by FKBP12.6. J Biol Chem 2003; 278:28856-64. [PMID: 12754204 DOI: 10.1074/jbc.m212440200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ca2+ homeostasis is a vital cellular control mechanism in which Ca2+ release from intracellular stores plays a central role. Ryanodine receptor (RyR)-mediated Ca2+ release is a key modulator of Ca2+ homeostasis, and the defective regulation of RyR is pathogenic. However, the molecular events underlying RyR-mediated pathology remain undefined. Cells stably expressing recombinant human RyR2 (Chinese hamster ovary cells, CHOhRyR2) had similar resting cytoplasmic Ca2+ levels ([Ca2+]c) to wild-type CHO cells (CHOWT) but exhibited increased cytoplasmic Ca2+ flux associated with decreased cell viability and proliferation. Intracellular Ca2+ flux increased with human RyR2 (hRyR2) expression levels and determined the extent of phenotypic modulation. Co-expression of FKBP12.6, but not FKBP12, or incubation of cells with ryanodine suppressed intracellular Ca2+ flux and restored normal cell viability and proliferation. Restoration of normal phenotype was independent of the status of resting [Ca2+]c or ER Ca2+ load. Heparin inhibition of endogenous inositol trisphosphate receptors (IP3R) had little effect on intracellular Ca2+ handling or viability. However, purinergic stimulation of endogenous IP3R resulted in apoptotic cell death mediated by hRyR2 suggesting functional interaction occurred between IP3R and hRyR2 Ca2+ release channels. These data demonstrate that defective regulation of RyR causes altered cellular phenotype via profound perturbations in intracellular Ca2+ signaling and highlight a key modulatory role of FKBP12.6 in hRyR2 Ca2+ channel function.
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Affiliation(s)
- Christopher H George
- Department of Cardiology, Wales Heart Research Institute, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, United Kingdom.
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36
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Koopman WJH, Bosch RR, van Emst-de Vries SE, Spaargaren M, De Pont JJHHM, Willems PHGM. R-Ras alters Ca2+ homeostasis by increasing the Ca2+ leak across the endoplasmic reticular membrane. J Biol Chem 2003; 278:13672-9. [PMID: 12586830 DOI: 10.1074/jbc.m211256200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Evidence in the literature implicating both Ras-like Ras (R-Ras) and intracellular Ca(2+) in programmed cell death and integrin-mediated adhesion prompted us to investigate the possibility that R-Ras alters cellular Ca(2+) handling. Chinese hamster ovary cells expressing the cholecystokinin (CCK)-A receptor were loaded with indo-1 to study the effects of constitutively active V38R-Ras and dominant negative N43R-Ras on the kinetics of the thapsigargin (Tg)- and CCK(8)-induced Ca(2+) rises using high speed confocal microscopy. In the absence of extracellular Ca(2+), both 1 microm Tg, a potent and selective inhibitor of the Ca(2+) pump of the intracellular Ca(2+) store, and 100 nm CCK(8) evoked a transient rise in Ca(2+), the size of which was decreased significantly after expression of V38R-Ras. At 0.1 nm, CCK(8) evoked periodic Ca(2+) rises. The frequency of these Ca(2+) oscillations was reduced significantly in V38R-Ras-expressing cells. In contrast to V38R-Ras, N43R-Ras did not alter the kinetics of the Tg- and CCK(8)-induced Ca(2+) rises. The present findings are compatible with the idea that V38R-Ras expression increases the passive leak of Ca(2+) of the store leading to a decrease in Ca(2+) content of this store, which, in turn, leads to a decrease in frequency of the CCK(8)-induced cytosolic Ca(2+) oscillations. The effect of V38R-Ras on the Ca(2+) content of the intracellular Ca(2+) store closely resembles that of the antiapoptotic protein Bcl-2 observed earlier. Together with reports on the role of dynamic Ca(2+) changes in integrin-mediated adhesion, this leads us to propose that the reduction in endoplasmic reticulum Ca(2+) content may underlie the antiapoptotic effect of R-Ras, whereas the decrease in frequency of stimulus-induced Ca(2+) oscillations may play a role in the inhibitory effect of R-Ras on stimulus-induced cell detachment and migration.
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Affiliation(s)
- Werner J H Koopman
- Department of Biochemistry, Nijmegen Center for Molecular Life Sciences, The Netherlands
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37
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Darios F, Lambeng N, Troadec JD, Michel PP, Ruberg M. Ceramide increases mitochondrial free calcium levels via caspase 8 and Bid: role in initiation of cell death. J Neurochem 2003; 84:643-54. [PMID: 12562509 DOI: 10.1046/j.1471-4159.2003.01590.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We investigated how the mitochondrial phase of ceramide-mediated cell death is initiated in nerve growth factor (NGF)-differentiated PC12 cells. We distinguished three independent effects of ceramide: free radical production; a transient increase in cytosolic free calcium; and a long-lasting increase in mitochondrial free calcium. Only the latter led to cell death, which could be prevented by buffering of mitochondrial calcium with the calcium binding protein calbindin D-28K ectopically expressed in mitochondria. We showed that mitochondrial calcium did not increase as a result of the increase in cytosolic free calcium levels. Rather, it appears to derive from the endoplasmic reticulum (ER) since dantrolene, which inhibits release of calcium from ER into cytosol through ryanodine receptors, prevented the increase in cytosolic free calcium but potentiated the increase in mitochondrial free calcium. This suggests that a transfer of calcium occurs directly, or very locally, between the two organelles. This transfer implicated activation of caspase 8 and cleavage of its substrate Bid, a previously unknown function of these cell death intermediaries. The increase in mitochondrial free calcium was also responsible for the release of cytochrome c into the cytosol, underlining the critical role it plays in ceramide-mediated cell death.
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Affiliation(s)
- Frédéric Darios
- INSERM U289, Hôpital de la Salpêtrière, 47 boulevard de l'Hôpital, 75013 Paris, France
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38
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Modulation of Calcium Homeostasis by the Endoplasmic Reticulum in Health and Disease. CALRETICULIN 2003. [DOI: 10.1007/978-1-4419-9258-1_11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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39
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Abstract
Intracellular Ca(2+)-transport ATPases exert a pivotal role in the endoplasmic reticulum and in the compartments of the cellular secretory pathway by maintaining a sufficiently high lumenal Ca(2+) (and Mn(2+)) concentration in these compartments required for an impressive number of vastly different cell functions. At the same time this lumenal Ca(2+) represents a store of releasable activator Ca(2+) controlling an equally impressive number of cytosolic functions. This review mainly focuses on the different Ca(2+)-transport ATPases found in the intracellular compartments of mainly animal non-muscle cells: the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) pumps. Although it is not our intention to treat the ATPases of the specialized sarcoplasmic reticulum in depth, we can hardly ignore the SERCA1 pump of fast-twitch skeletal muscle since its structure and function is by far the best understood and it can serve as a guide to understand the other members of the family. In a second part of this review we describe the relatively novel family of secretory pathway Ca(2+)/Mn(2+) ATPases (SPCA), which in eukaryotic cells are primarily found in the Golgi compartment.
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Affiliation(s)
- F Wuytack
- Laboratorium voor Fysiologie, K.U.Leuven, Campus Gasthuisberg, Leuven, Belgium.
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40
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Ferrari D, Pinton P, Szabadkai G, Chami M, Campanella M, Pozzan T, Rizzuto R. Endoplasmic reticulum, Bcl-2 and Ca2+ handling in apoptosis. Cell Calcium 2002; 32:413-20. [PMID: 12543100 DOI: 10.1016/s0143416002002014] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the complex signalling interplay that allows extracellular signals to be decoded into activation of apoptotic cell death, Ca(2+) plays a significant role. This is supported not only by evidence linking alterations in Ca(2+) homeostasis to the triggering of apoptotic (and in some cases necrotic) cell death, but also by recent data indicating that a key anti-apoptotic protein, Bcl-2, has a direct effect on ER Ca(2+) handling. We will briefly summarise the first aspect, and describe in more detail these new data, demonstrating that (i) Bcl-2 reduces the state of filling of the ER Ca(2+) store and (ii) this Ca(2+) signalling alteration renders the cells less sensitive to apoptotic stimuli. Overall, these results suggest that calcium homeostasis may represent a pharmacological target in the fundamental pathological process of apoptosis.
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Affiliation(s)
- D Ferrari
- Department of Experimental Medicine, Section of General Pathology, Telethon Center for Cell Imaging, Interdisciplinary Center for the Study of Inflammation, University of Ferrara, Via Borsari 46, I-44100, Ferrara, Italy
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Abstract
BACKGROUND Darier's disease (DD) is a rare autosomal dominant disorder of keratinization caused by a mutation of the ATP2A2 gene. There is little information on the behaviour of Bcl-2, Bax and Bcl-x in DD. OBJECTIVES To investigate the dynamic control and the behaviour of Bax, Bcl-2 and Bcl-x in DD. We asked whether members of the Bcl-2 family might manifest their effects through modulation of intracellular calcium signalling or whether the gene that encodes the sarco/endoplasmic reticulum Ca2+ ATPase isoform 2 (SERCA2) modulates the Bcl-2 family in the regulation of apoptosis in DD. Methods Immunohistochemical methods were used. RESULTS There was no immunoreactivity for Bcl-2 and Bcl-x in epidermal keratinocytes in lesional epidermis. Staining for Bax was evident in the cells of the perilesional uninvolved skin, but decreased in the epidermal cells of lesional involved skin. CONCLUSIONS The decrease or absence of Bcl-2 and Bcl-x and the imbalance of Bax in the epithelial cells of affected DD skin is likely to be an important control point determined by the genetic mutation of SERCA2, which modifies the programme of the antiapoptotic proteins. The consequent imbalance of the factors controlling apoptosis in keratinocytes underlines another apoptotic pathway responsible for the dyskeratotic cells in DD.
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Affiliation(s)
- M R Bongiorno
- Department of Dermatology, University of Palermo, Via del Vespro 131, Italy.
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Xie Q, Khaoustov VI, Chung CC, Sohn J, Krishnan B, Lewis DE, Yoffe B. Effect of tauroursodeoxycholic acid on endoplasmic reticulum stress-induced caspase-12 activation. Hepatology 2002; 36:592-601. [PMID: 12198651 DOI: 10.1053/jhep.2002.35441] [Citation(s) in RCA: 253] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Activation of death receptors and mitochondrial damage are well-described common apoptotic pathways. Recently, a novel pathway via endoplasmic reticulum (ER) stress has been reported. We assessed the role of tauroursodeoxycholic acid (TUDCA) in inhibition of caspase-12 activation and its effect on calcium homeostasis in an ER stress-induced model of apoptosis. The human liver-derived cell line, Huh7, was treated with thapsigargin (TG) to induce ER stress. Typical morphologic changes of ER stress preceded development of apoptotic changes, including DNA fragmentation and cleavage of poly (adenosine diphosphate-ribose) polymerase (PARP), as well as activation of caspase-3 and -7. Elevation of intracellular calcium levels without loss of mitochondrial membrane potential (MMP) was shown using Fluo-3/Fura-red labeling and flow cytometry, and confirmed by induction of Bip/GRP78, a calcium-dependent chaperon of ER lumen. These changes were accompanied by procaspase-12 processing. TUDCA abolished TG-induced markers of ER stress; reduced calcium efflux, induction of Bip/GRP78, and caspase-12 activation; and subsequently inhibited activation of effector caspases and apoptosis. In conclusion, we propose that mitochondria play a secondary role in ER-mediated apoptosis and that TUDCA prevents apoptosis by blocking a calcium-mediated apoptotic pathway as well as caspase-12 activation. This novel mechanism of TUDCA action suggests new intervention methods for ER stress-induced liver disease.
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Affiliation(s)
- Qing Xie
- Department of Medicine, Veterans Affairs Medical Center, Houston, TX 77030, USA
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43
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Abstract
Changes in the cytosolic Ca(2+) concentration ([Ca(2+)](c)) translate a variety of extracellular signals into widely diverse intracellular effects, ranging from secretion to movement, proliferation and also cell death. As regards the last one, it has long been known that large [Ca(2+)](c) increases lead cells to death. More recently, experimental evidence has been obtained that the oncogene Bcl-2 reduces the state of filling of intracellular Ca(2+) stores and thus affects the Ca(2+) responses induced by physiological and pathological stimuli. In this contribution, we will discuss this effect and its significance for the mechanism of action of Bcl-2, an important checkpoint of the apoptotic process.
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Affiliation(s)
- Paolo Pinton
- Department of Biomedical Sciences and CNR Center for the Study of Biomembranes, University of Padova, Via Colombo 3, 35121 Padova, Italy
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44
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Chami M, Gozuacik D, Lagorce D, Brini M, Falson P, Peaucellier G, Pinton P, Lecoeur H, Gougeon ML, le Maire M, Rizzuto R, Bréchot C, Paterlini-Bréchot P. SERCA1 truncated proteins unable to pump calcium reduce the endoplasmic reticulum calcium concentration and induce apoptosis. J Cell Biol 2001; 153:1301-14. [PMID: 11402072 PMCID: PMC2192035 DOI: 10.1083/jcb.153.6.1301] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
By pumping calcium from the cytosol to the ER, sarco/endoplasmic reticulum calcium ATPases (SERCAs) play a major role in the control of calcium signaling. We describe two SERCA1 splice variants (S1Ts) characterized by exon 4 and/or exon 11 splicing, encoding COOH terminally truncated proteins, having only one of the seven calcium-binding residues, and thus unable to pump calcium. As shown by semiquantitative RT-PCR, S1T transcripts are differentially expressed in several adult and fetal human tissues, but not in skeletal muscle and heart. S1T proteins expression was detected by Western blot in nontransfected cell lines. In transiently transfected cells, S1T homodimers were revealed by Western blot using mildly denaturing conditions. S1T proteins were shown, by confocal scanning microscopy, to colocalize with endogenous SERCA2b into the ER membrane. Using ER-targeted aequorin (erAEQ), we have found that S1T proteins reduce ER calcium and reverse elevation of ER calcium loading induced by SERCA1 and SERCA2b. Our results also show that SERCA1 variants increase ER calcium leakage and are consistent with the hypothesis of a cation channel formed by S1T homodimers. Finally, when overexpressed in liver-derived cells, S1T proteins significantly induce apoptosis. These data reveal a further mechanism modulating Ca(2+) accumulation into the ER of nonmuscle cells and highlight the relevance of S1T proteins to the control of apoptosis.
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Affiliation(s)
- Mounia Chami
- The French Institute of Health and Medical Research Institut National de la Santé et de la Recherche Médicale (INSERM/Pasteur U370)/Necker Faculty Institute of Medicine, 75015 Paris, France
| | - Devrim Gozuacik
- The French Institute of Health and Medical Research Institut National de la Santé et de la Recherche Médicale (INSERM/Pasteur U370)/Necker Faculty Institute of Medicine, 75015 Paris, France
| | - David Lagorce
- The French Institute of Health and Medical Research Institut National de la Santé et de la Recherche Médicale (INSERM/Pasteur U370)/Necker Faculty Institute of Medicine, 75015 Paris, France
| | - Marisa Brini
- Department of Biochemistry and Center for the Study of Biomembranes of the National Research Council (CNR), University of Padova, 35121 Padova, Italy
| | - Pierre Falson
- URA Centre National de Recherche Scientifique (CNRS) 2096, CEA Saclay, 91191 Gif sur Yvette, France
| | - Gérard Peaucellier
- National Center Scientific Research, URA 2156, Arago Laboratory, F66651 Banyuls sur mer, France
| | - Paolo Pinton
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, 44100 Ferrara, Italy
| | - Hervé Lecoeur
- Pasteur Institute, Unit of Viral Oncology, SIDA Department of Retrovirus, 75015 Paris, France
| | - Marie-Lyse Gougeon
- Pasteur Institute, Unit of Viral Oncology, SIDA Department of Retrovirus, 75015 Paris, France
| | - Marc le Maire
- URA Centre National de Recherche Scientifique (CNRS) 2096, CEA Saclay, 91191 Gif sur Yvette, France
| | - Rosario Rizzuto
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, 44100 Ferrara, Italy
| | - Christian Bréchot
- The French Institute of Health and Medical Research Institut National de la Santé et de la Recherche Médicale (INSERM/Pasteur U370)/Necker Faculty Institute of Medicine, 75015 Paris, France
| | - Patrizia Paterlini-Bréchot
- The French Institute of Health and Medical Research Institut National de la Santé et de la Recherche Médicale (INSERM/Pasteur U370)/Necker Faculty Institute of Medicine, 75015 Paris, France
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Robert V, Massimino ML, Tosello V, Marsault R, Cantini M, Sorrentino V, Pozzan T. Alteration in calcium handling at the subcellular level in mdx myotubes. J Biol Chem 2001; 276:4647-51. [PMID: 11029464 DOI: 10.1074/jbc.m006337200] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study, we have tested the hypothesis that augmented [Ca(2+)] in subcellular regions or organelles, which are known to play a key role in cell survival, is the missing link between Ca(2+) homeostasis alterations and muscular degeneration associated with muscular dystrophy. To this end, different targeted chimeras of the Ca(2+)-sensitive photoprotein aequorin have been transiently expressed in subcellular compartments of skeletal myotubes of mdx mice, the animal model of Duchenne muscular dystrophy. Direct measurements of the [Ca(2+)] in the sarcoplasmic reticulum, [Ca(2+)](sr), show a higher steady state level at rest and a larger drop after KCl-induced depolarization in mdx compared with control myotubes. The peaks in [Ca(2+)] occurring in the mitochondrial matrix of mdx myotubes are significantly larger than in controls upon KCl-induced depolarization or caffeine application. The augmented response of mitochondria precedes the alterations in the Ca(2+) responses of the cytosol and of the cytoplasmic region beneath the membrane, which become significant only at a later stage of myotube differentiation. Taking into account the key role played by mitochondria Ca(2+) handling in the control of cell death, our data suggest that mitochondria are potential targets of impaired Ca(2+) homeostasis in muscular dystrophy.
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Affiliation(s)
- V Robert
- Department of Biomedical Sciences, CNR Center of Biomembranes, University of Padova, 35131 Padua, Italy
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46
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Pinton P, Ferrari D, Di Virgilio F, Pozzan T, Rizzuto R. Molecular machinery and signaling events in apoptosis. Drug Dev Res 2001. [DOI: 10.1002/ddr.1159] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Hajnóczky G, Csordás G, Madesh M, Pacher P. Control of apoptosis by IP(3) and ryanodine receptor driven calcium signals. Cell Calcium 2000; 28:349-63. [PMID: 11115374 DOI: 10.1054/ceca.2000.0169] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Intracellular calcium signals mediated by IP(3)and ryanodine receptors (IP(3)R/RyR) play a central role in cell survival, but emerging evidence suggests that IP(3)R/RyR are also important in apoptotic cell death. Switch from the life program to the death program may involve coincident detection of proapoptotic stimuli and calcium signals or changes in the spatiotemporal pattern of the calcium signal or changes at the level of effectors activated by the calcium signal (e.g. calpain, calcineurin). The fate of the cell is often determined in the mitochondria, where calcium spikes may support cell survival through stimulation of ATP production or initiate apoptosis v ia opening of the permeability transition pore and release of apoptotic factors such as cytochrome c. The functional importance of these mitochondrial calcium signalling pathways has been underscored by the elucidation of a highly effective, local Ca(2+)coupling between IP(3)R/RyR and mitochondrial Ca(2+)uptake sites. This article will focus on the IP(3)R/RyR-dependent pathways to apoptosis, particularly on the mitochondrial phase of the death cascade.
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Affiliation(s)
- G Hajnóczky
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia 19107, USA.
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48
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Chami M, Gozuacik D, Saigo K, Capiod T, Falson P, Lecoeur H, Urashima T, Beckmann J, Gougeon ML, Claret M, le Maire M, Bréchot C, Paterlini-Bréchot P. Hepatitis B virus-related insertional mutagenesis implicates SERCA1 gene in the control of apoptosis. Oncogene 2000; 19:2877-86. [PMID: 10871838 DOI: 10.1038/sj.onc.1203605] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We have used the Hepatitis B Virus DNA genome as a probe to identify genes clonally mutated in vivo, in human liver cancers. In a tumor, HBV-DNA was found to be integrated into the gene encoding Sarco/Endoplasmic Reticulum Calcium ATPase (SERCA), which pumps calcium, an important intracellular messenger for cell viability and growth, from the cytosol to the endoplasmic reticulum. The HBV X gene promoter cis-activates chimeric HBV X/SERCA1 transcripts, with splicing of SERCA1 exon 11, encoding C-terminally truncated SERCA1 proteins. Two chimeric HBV X/SERCA1 proteins accumulate in the tumor and form dimers. In vitro analyses have demonstrated that these proteins localize to the ER, determine its calcium depletion and induce cell death. We have also shown that these biological effects are related to expression of the SERCA, rather than of the viral moiety. This report involves for the first time the expression of mutated SERCA proteins in vivo in a tumor cell proliferation and in vitro in the control of cell viability. Oncogene (2000).
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Affiliation(s)
- M Chami
- U-370 INSERM, Necker Institute, 75015 Paris, France
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49
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Pinton P, Ferrari D, Magalhães P, Schulze-Osthoff K, Di Virgilio F, Pozzan T, Rizzuto R. Reduced loading of intracellular Ca(2+) stores and downregulation of capacitative Ca(2+) influx in Bcl-2-overexpressing cells. J Cell Biol 2000; 148:857-62. [PMID: 10704437 PMCID: PMC2174537 DOI: 10.1083/jcb.148.5.857] [Citation(s) in RCA: 374] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mechanism of action of the oncogene bcl-2, a key regulator of the apoptotic process, is still debated. We have employed organelle-targeted chimeras of the Ca(2+)-sensitive photoprotein, aequorin, to investigate in detail the effect of Bcl-2 overexpression on intracellular Ca(2+) homeostasis. In the ER and the Golgi apparatus, Bcl-2 overexpression increases the Ca(2+) leak (while leaving Ca(2+) accumulation unaffected), hence reducing the steady-state [Ca(2+)] levels. As a direct consequence, the [Ca(2+)] increases caused by inositol 1,4,5 trisphosphate (IP3)-generating agonists were reduced in amplitude in both the cytosol and the mitochondria. Bcl-2 overexpression also reduced the rate of Ca(2+) influx activated by Ca(2+) store depletion, possibly by an adaptive downregulation of this pathway. By interfering with Ca(2+)-dependent events at multiple intracellular sites, these effects of Bcl-2 on intracellular Ca(2+) homeostasis may contribute to the protective role of this oncogene against programmed cell death.
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Affiliation(s)
- Paolo Pinton
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche (CNR) Center for the Study of Biomembranes, University of Padova, 35121 Padova, Italy
| | - Davide Ferrari
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, 44100 Ferrara, Italy
| | - Paulo Magalhães
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche (CNR) Center for the Study of Biomembranes, University of Padova, 35121 Padova, Italy
| | | | - Francesco Di Virgilio
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, 44100 Ferrara, Italy
| | - Tullio Pozzan
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche (CNR) Center for the Study of Biomembranes, University of Padova, 35121 Padova, Italy
| | - Rosario Rizzuto
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, 44100 Ferrara, Italy
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