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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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Sanders KM, Drumm BT, Cobine CA, Baker SA. Ca 2+ dynamics in interstitial cells: foundational mechanisms for the motor patterns in the gastrointestinal tract. Physiol Rev 2024; 104:329-398. [PMID: 37561138 PMCID: PMC11281822 DOI: 10.1152/physrev.00036.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 06/29/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023] Open
Abstract
The gastrointestinal (GI) tract displays multiple motor patterns that move nutrients and wastes through the body. Smooth muscle cells (SMCs) provide the forces necessary for GI motility, but interstitial cells, electrically coupled to SMCs, tune SMC excitability, transduce inputs from enteric motor neurons, and generate pacemaker activity that underlies major motor patterns, such as peristalsis and segmentation. The interstitial cells regulating SMCs are interstitial cells of Cajal (ICC) and PDGF receptor (PDGFR)α+ cells. Together these cells form the SIP syncytium. ICC and PDGFRα+ cells express signature Ca2+-dependent conductances: ICC express Ca2+-activated Cl- channels, encoded by Ano1, that generate inward current, and PDGFRα+ cells express Ca2+-activated K+ channels, encoded by Kcnn3, that generate outward current. The open probabilities of interstitial cell conductances are controlled by Ca2+ release from the endoplasmic reticulum. The resulting Ca2+ transients occur spontaneously in a stochastic manner. Ca2+ transients in ICC induce spontaneous transient inward currents and spontaneous transient depolarizations (STDs). Neurotransmission increases or decreases Ca2+ transients, and the resulting depolarizing or hyperpolarizing responses conduct to other cells in the SIP syncytium. In pacemaker ICC, STDs activate voltage-dependent Ca2+ influx, which initiates a cluster of Ca2+ transients and sustains activation of ANO1 channels and depolarization during slow waves. Regulation of GI motility has traditionally been described as neurogenic and myogenic. Recent advances in understanding Ca2+ handling mechanisms in interstitial cells and how these mechanisms influence motor patterns of the GI tract suggest that the term "myogenic" should be replaced by the term "SIPgenic," as this review discusses.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada-Reno, Reno, Nevada, United States
| | - Bernard T Drumm
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Caroline A Cobine
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Salah A Baker
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada-Reno, Reno, Nevada, United States
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3
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Dentoni G, Castro-Aldrete L, Naia L, Ankarcrona M. The Potential of Small Molecules to Modulate the Mitochondria–Endoplasmic Reticulum Interplay in Alzheimer’s Disease. Front Cell Dev Biol 2022; 10:920228. [PMID: 36092728 PMCID: PMC9459385 DOI: 10.3389/fcell.2022.920228] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 06/08/2022] [Indexed: 11/13/2022] Open
Abstract
Alzheimer’s disease (AD) is the most common neurodegenerative disease affecting a growing number of elderly individuals. No disease-modifying drugs have yet been identified despite over 30 years of research on the topic, showing the need for further research on this multifactorial disease. In addition to the accumulation of amyloid β-peptide (Aβ) and hyperphosphorylated tau (p-tau), several other alterations have been associated with AD such as calcium (Ca2+) signaling, glucose-, fatty acid-, cholesterol-, and phospholipid metabolism, inflammation, and mitochondrial dysfunction. Interestingly, all these processes have been associated with the mitochondria–endoplasmic reticulum (ER) contact site (MERCS) signaling hub. We and others have hypothesized that the dysregulated MERCS function may be one of the main pathogenic pathways driving AD pathology. Due to the variety of biological processes overseen at the MERCS, we believe that they constitute unique therapeutic targets to boost the neuronal function and recover neuronal homeostasis. Thus, developing molecules with the capacity to correct and/or modulate the MERCS interplay can unleash unique therapeutic opportunities for AD. The potential pharmacological intervention using MERCS modulators in different models of AD is currently under investigation. Here, we survey small molecules with the potential to modulate MERCS structures and functions and restore neuronal homeostasis in AD. We will focus on recently reported examples and provide an overview of the current challenges and future perspectives to develop MERCS modulators in the context of translational research.
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4
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Çoku J, Booth DM, Skoda J, Pedrotty MC, Vogel J, Liu K, Vu A, Carpenter EL, Ye JC, Chen MA, Dunbar P, Scadden E, Yun TD, Nakamaru-Ogiso E, Area-Gomez E, Li Y, Goldsmith KC, Reynolds CP, Hajnoczky G, Hogarty MD. Reduced ER-mitochondria connectivity promotes neuroblastoma multidrug resistance. EMBO J 2022; 41:e108272. [PMID: 35211994 PMCID: PMC9016347 DOI: 10.15252/embj.2021108272] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 01/14/2022] [Accepted: 01/24/2022] [Indexed: 12/22/2022] Open
Abstract
Most cancer deaths result from progression of therapy resistant disease, yet our understanding of this phenotype is limited. Cancer therapies generate stress signals that act upon mitochondria to initiate apoptosis. Mitochondria isolated from neuroblastoma cells were exposed to tBid or Bim, death effectors activated by therapeutic stress. Multidrug‐resistant tumor cells obtained from children at relapse had markedly attenuated Bak and Bax oligomerization and cytochrome c release (surrogates for apoptotic commitment) in comparison with patient‐matched tumor cells obtained at diagnosis. Electron microscopy identified reduced ER–mitochondria‐associated membranes (MAMs; ER–mitochondria contacts, ERMCs) in therapy‐resistant cells, and genetically or biochemically reducing MAMs in therapy‐sensitive tumors phenocopied resistance. MAMs serve as platforms to transfer Ca2+ and bioactive lipids to mitochondria. Reduced Ca2+ transfer was found in some but not all resistant cells, and inhibiting transfer did not attenuate apoptotic signaling. In contrast, reduced ceramide synthesis and transfer was common to resistant cells and its inhibition induced stress resistance. We identify ER–mitochondria‐associated membranes as physiologic regulators of apoptosis via ceramide transfer and uncover a previously unrecognized mechanism for cancer multidrug resistance.
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Affiliation(s)
- Jorida Çoku
- Cancer Biology Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David M Booth
- MitoCare Center, Department of Pathology, Anatomy & Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Jan Skoda
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital, Brno, Czech Republic
| | - Madison C Pedrotty
- Division of Oncology and Center for Childhood Cancer Research, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Jennifer Vogel
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kangning Liu
- Division of Oncology and Center for Childhood Cancer Research, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Annette Vu
- Division of Oncology and Center for Childhood Cancer Research, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Erica L Carpenter
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jamie C Ye
- Division of Oncology and Center for Childhood Cancer Research, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Michelle A Chen
- Division of Oncology and Center for Childhood Cancer Research, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Peter Dunbar
- Division of Oncology and Center for Childhood Cancer Research, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Elizabeth Scadden
- Division of Oncology and Center for Childhood Cancer Research, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Taekyung D Yun
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, USA
| | - Eiko Nakamaru-Ogiso
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Estela Area-Gomez
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, USA
| | - Yimei Li
- Department of Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kelly C Goldsmith
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - C Patrick Reynolds
- TTUHSC Cancer Center, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Gyorgy Hajnoczky
- MitoCare Center, Department of Pathology, Anatomy & Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Michael D Hogarty
- Division of Oncology and Center for Childhood Cancer Research, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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5
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Abstract
The uptake of calcium into and extrusion of calcium from the mitochondrial matrix is a fundamental biological process that has critical effects on cellular metabolism, signaling, and survival. Disruption of mitochondrial calcium (mCa2+) cycling is implicated in numerous acquired diseases such as heart failure, stroke, neurodegeneration, diabetes, and cancer, and is genetically linked to several inherited neuromuscular disorders. Understanding the mechanisms responsible for mCa2+ exchange therefore holds great promise for the treatment of these diseases. The past decade has seen the genetic identification of many of the key proteins that mediate mitochondrial calcium uptake and efflux. Here, we present an overview of the phenomenon of mCa2+ transport, and a comprehensive examination of the molecular machinery that mediates calcium flux across the inner mitochondrial membrane: the mitochondrial uniporter complex (consisting of MCU, EMRE, MICU1, MICU2, MICU3, MCUB, and MCUR1), NCLX, LETM1, the mitochondrial ryanodine receptor, and the mitochondrial permeability transition pore. We then consider the physiological implications of mCa2+ flux and evaluate how alterations in mCa2+ homeostasis contribute to human disease. This review concludes by highlighting opportunities and challenges for therapeutic intervention in pathologies characterized by aberrant mCa2+ handling and by summarizing critical unanswered questions regarding the biology of mCa2+ flux.
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Affiliation(s)
- Joanne F Garbincius
- Center for Translational Medicine, Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
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6
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Resveratrol Treatment in Human Parkin-Mutant Fibroblasts Modulates cAMP and Calcium Homeostasis Regulating the Expression of Mitochondria-Associated Membranes Resident Proteins. Biomolecules 2021; 11:biom11101511. [PMID: 34680144 PMCID: PMC8534032 DOI: 10.3390/biom11101511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/12/2021] [Accepted: 10/13/2021] [Indexed: 12/16/2022] Open
Abstract
Parkin plays an important role in ensuring efficient mitochondrial function and calcium homeostasis. Parkin-mutant human fibroblasts, with defective oxidative phosphorylation activity, showed high basal cAMP level likely ascribed to increased activity/expression of soluble adenylyl cyclase and/or low expression/activity of the phosphodiesterase isoform 4 and to a higher Ca2+ level. Overall, these findings support the existence, in parkin-mutant fibroblasts, of an abnormal Ca2+ and cAMP homeostasis in mitochondria. In our previous studies resveratrol treatment of parkin-mutant fibroblasts induced a partial rescue of mitochondrial functions associated with stimulation of the AMPK/SIRT1/PGC-1α pathway. In this study we provide additional evidence of the potential beneficial effects of resveratrol inducing an increase in the pre-existing high Ca2+ level and remodulation of the cAMP homeostasis in parkin-mutant fibroblasts. Consistently, we report in these fibroblasts higher expression of proteins implicated in the tethering of ER and mitochondrial contact sites along with their renormalization after resveratrol treatment. On this basis we hypothesize that resveratrol-mediated enhancement of the Ca2+ level, fine-tuned by the ER-mitochondria Ca2+ crosstalk, might modulate the pAMPK/AMPK pathway in parkin-mutant fibroblasts.
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7
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Communications between Mitochondria and Endoplasmic Reticulum in the Regulation of Metabolic Homeostasis. Cells 2021; 10:cells10092195. [PMID: 34571844 PMCID: PMC8468463 DOI: 10.3390/cells10092195] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/12/2021] [Accepted: 08/16/2021] [Indexed: 12/18/2022] Open
Abstract
Mitochondria associated membranes (MAM), which are the contact sites between endoplasmic reticulum (ER) and mitochondria, have emerged as an important hub for signaling molecules to integrate the cellular and organelle homeostasis, thus facilitating the adaptation of energy metabolism to nutrient status. This review explores the dynamic structural and functional features of the MAM and summarizes the various abnormalities leading to the impaired insulin sensitivity and metabolic diseases.
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8
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Mitochondrial metabolism and calcium homeostasis in the development of NAFLD leading to hepatocellular carcinoma. Mitochondrion 2021; 58:24-37. [PMID: 33581332 DOI: 10.1016/j.mito.2021.01.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 01/21/2021] [Accepted: 01/25/2021] [Indexed: 02/06/2023]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a metabolic syndrome characterized by excessive accumulation of hepatic lipid droplets. The disease progresses with steatosis as the premise for hepatocytic damage and tissue scarring, often culminating in hepatocellular carcinoma (HCC). Perturbations in mitochondrial metabolism and energetics were found to be associated with, and often instrumental in various stages of this progression. Functional impairment of the mitochondria affects all aspects of cellular functioning and a particularly important one is calcium signalling. Changes in mitochondrial calcium specifically in hepatocytes of a fatty liver, is reflected by alterations in calcium signalling as well as calcium transporter activities. This deranged Ca2+ homeostasis aids in even more uptake of lipids into the mitochondria and a shift in equilibrium, both metabolically as well as in terms of energy production, leading to completely altered cellular states. These alterations have been reviewed as a perspective to understand the disease progression through NAFLD leading to HCC.
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9
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ER-Mitochondria Contact Sites Reporters: Strengths and Weaknesses of the Available Approaches. Int J Mol Sci 2020; 21:ijms21218157. [PMID: 33142798 PMCID: PMC7663704 DOI: 10.3390/ijms21218157] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/28/2020] [Accepted: 10/30/2020] [Indexed: 12/12/2022] Open
Abstract
Organelle intercommunication represents a wide area of interest. Over the last few decades, increasing evidence has highlighted the importance of organelle contact sites in many biological processes including Ca2+ signaling, lipid biosynthesis, apoptosis, and autophagy but also their involvement in pathological conditions. ER–mitochondria tethering is one of the most investigated inter-organelle communications and it is differently modulated in response to several cellular conditions including, but not limited to, starvation, Endoplasmic Reticulum (ER) stress, and mitochondrial shape modifications. Despite many studies aiming to understand their functions and how they are perturbed under different conditions, approaches to assess organelle proximity are still limited. Indeed, better visualization and characterization of contact sites remain a fascinating challenge. The aim of this review is to summarize strengths and weaknesses of the available methods to detect and quantify contact sites, with a main focus on ER–mitochondria tethering.
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10
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Zhang Y, Wang J, Xing S, Li L, Zhao S, Zhu W, Liang K, Liu Y, Chen L. Mitochondria determine the sequential propagation of the calcium macrodomains revealed by the super-resolution calcium lantern imaging. SCIENCE CHINA-LIFE SCIENCES 2020; 63:1543-1551. [PMID: 32279282 DOI: 10.1007/s11427-019-1659-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 02/27/2020] [Indexed: 01/02/2023]
Abstract
Despite the wide application of super-resolution (SR) microscopy in biological studies of cells, the technology is rarely used to monitor functional changes in live cells. By combining fast spinning disc-confocal structured illumination microscopy (SD-SIM) with loading of cytosolic fluorescent Ca2+ indicators, we have developed an SR method for visualization of regional Ca2+ dynamics and related cellular organelle morphology and dynamics, termed SR calcium lantern imaging. In COS-7 cells stimulated with ATP, we have identified various calcium macrodomains characterized by different types of Ca2+ release from endoplasmic reticulum (ER) stores. Finally, we demonstrated various roles of mitochondria in mediating calcium signals from different sources; while mitochondria can globally potentiate the Ca2+ entry associated with store release, mitochondria also locally control Ca2+ release from the neighboring ER stores and assist in their refilling processes.
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Affiliation(s)
- Yulin Zhang
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Jianyong Wang
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Shijia Xing
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Liuju Li
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Shiqun Zhao
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Wenzhen Zhu
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Kuo Liang
- Department of General Surgery, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China
| | - Yanmei Liu
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking University, Beijing, 100871, China.,Institute for Brain Research and Rehabilitation (IBRR), Guangdong Key Laboratory of Mental Health and Cognitive Science, South China Normal University, Guangzhou, 200062, China
| | - Liangyi Chen
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking University, Beijing, 100871, China. .,PKU-IDG/McGovern Institute for Brain Research, Beijing, 100871, China.
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11
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Vallese F, Barazzuol L, Maso L, Brini M, Calì T. ER-Mitochondria Calcium Transfer, Organelle Contacts and Neurodegenerative Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:719-746. [PMID: 31646532 DOI: 10.1007/978-3-030-12457-1_29] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
It is generally accepted that interorganellar contacts are central to the control of cellular physiology. Virtually, any intracellular organelle can come into proximity with each other and, by establishing physical protein-mediated contacts within a selected fraction of the membrane surface, novel specific functions are acquired. Endoplasmic reticulum (ER) contacts with mitochondria are among the best studied and have a major role in Ca2+ and lipid transfer, signaling, and membrane dynamics.Their functional (and structural) diversity, their dynamic nature as well as the growing number of new players involved in the tethering concurred to make their monitoring difficult especially in living cells. This review focuses on the most established examples of tethers/modulators of the ER-mitochondria interface and on the roles of these contacts in health and disease by specifically dissecting how Ca2+ transfer occurs and how mishandling eventually leads to disease. Additional functions of the ER-mitochondria interface and an overview of the currently available methods to measure/quantify the ER-mitochondria interface will also be discussed.
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Affiliation(s)
- Francesca Vallese
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Lucia Barazzuol
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Lorenzo Maso
- Department of Biology, University of Padua, Padua, Italy
| | - Marisa Brini
- Department of Biology, University of Padua, Padua, Italy.
| | - Tito Calì
- Department of Biomedical Sciences, University of Padua, Padua, Italy. .,Padua Neuroscience Center (PNC), Padua, Italy.
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12
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Bartok A, Weaver D, Golenár T, Nichtova Z, Katona M, Bánsághi S, Alzayady KJ, Thomas VK, Ando H, Mikoshiba K, Joseph SK, Yule DI, Csordás G, Hajnóczky G. IP 3 receptor isoforms differently regulate ER-mitochondrial contacts and local calcium transfer. Nat Commun 2019; 10:3726. [PMID: 31427578 PMCID: PMC6700175 DOI: 10.1038/s41467-019-11646-3] [Citation(s) in RCA: 180] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 07/12/2019] [Indexed: 12/31/2022] Open
Abstract
Contact sites of endoplasmic reticulum (ER) and mitochondria locally convey calcium signals between the IP3 receptors (IP3R) and the mitochondrial calcium uniporter, and are central to cell survival. It remains unclear whether IP3Rs also have a structural role in contact formation and whether the different IP3R isoforms have redundant functions. Using an IP3R-deficient cell model rescued with each of the three IP3R isoforms and an array of super-resolution and ultrastructural approaches we demonstrate that IP3Rs are required for maintaining ER-mitochondrial contacts. This role is independent of calcium fluxes. We also show that, while each isoform can support contacts, type 2 IP3R is the most effective in delivering calcium to the mitochondria. Thus, these studies reveal a non-canonical, structural role for the IP3Rs and direct attention towards the type 2 IP3R that was previously neglected in the context of ER-mitochondrial calcium signaling.
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Affiliation(s)
- Adam Bartok
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
- Departent of Medical Biochemistry, Semmelweis University, Budapest, Hungary
| | - David Weaver
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Tünde Golenár
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Zuzana Nichtova
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Máté Katona
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Száva Bánsághi
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Kamil J Alzayady
- Department of Physiology and Pharmacology, University of Rochester, Rochester, NY, USA
| | - V Kaye Thomas
- Department of Physiology and Pharmacology, University of Rochester, Rochester, NY, USA
| | - Hideaki Ando
- Lab for Developmental Neurobiology, RIKEN Brain Science Institute, Saitama, Japan
- Laboratory of Molecular Biomedicine for Pathogenesis, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Katsuhiko Mikoshiba
- Lab for Developmental Neurobiology, RIKEN Brain Science Institute, Saitama, Japan
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, 201210, Shanghai, China
| | - Suresh K Joseph
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - David I Yule
- Department of Physiology and Pharmacology, University of Rochester, Rochester, NY, USA
| | - György Csordás
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA.
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA.
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13
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Fernandez-Sanz C, De la Fuente S, Sheu SS. Mitochondrial Ca 2+ concentrations in live cells: quantification methods and discrepancies. FEBS Lett 2019; 593:1528-1541. [PMID: 31058316 DOI: 10.1002/1873-3468.13427] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 04/29/2019] [Accepted: 05/02/2019] [Indexed: 12/11/2022]
Abstract
Intracellular Ca2+ signaling controls numerous cellular functions. Mitochondria respond to cytosolic Ca2+ changes by adapting mitochondrial functions and, in some cell types, shaping the spatiotemporal properties of the cytosolic Ca2+ signal. Numerous methods have been developed to specifically and quantitatively measure the mitochondrial-free Ca2+ concentrations ([Ca2+ ]m ), but there are still significant discrepancies in the calculated absolute values of [Ca2+ ]m in stimulated live cells. These discrepancies may be due to the distinct properties of the methods used to measure [Ca2+ ]m , the calcium-free/bound ratio, and the cell-type and stimulus-dependent Ca2+ dynamics. Critical processes happening in the mitochondria, such as ATP generation, ROS homeostasis, and mitochondrial permeability transition opening, depend directly on the [Ca2+ ]m values. Thus, precise determination of absolute [Ca2+ ]m values is imperative for understanding Ca2+ signaling. This review summarizes the reported calibrated [Ca2+ ]m values in many cell types and discusses the discrepancies among these values. Areas for future research are also proposed.
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Affiliation(s)
- Celia Fernandez-Sanz
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, PA, USA
| | - Sergio De la Fuente
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, PA, USA
| | - Shey-Shing Sheu
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, PA, USA
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14
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Shu HY, Li HC, Xie WQ, Ni B, Zhou HY. Mitochondrial DNA variations in tongue squamous cell carcinoma. Biomed Rep 2018; 10:23-28. [PMID: 30588299 DOI: 10.3892/br.2018.1167] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 10/26/2018] [Indexed: 12/20/2022] Open
Abstract
Tongue squamous cell carcinoma (TSCC) is the most common type of oral carcinoma. Mitochondrial DNA (mtDNA) is a circular DNA molecule of 16,569 bp, which functionally encompasses a regulatory non-coding region (D-loop) and 37 encoding genes that correspond to 13 subunits of respiratory chain complexes (I, III, IV and V), 22 transfer RNAs and 2 ribosomal (r)RNAs. Recently, mtDNA has been implicated as a mutation hotspot in various tumors. However, to our knowledge mtDNA alteration in TSCC has not been investigated to date. In the present study, the mitochondrial genomes of tongue carcinoma, adjacent non-cancerous tissue and peripheral blood samples from 8 patients with TSCC were sequenced and aligned with the revised Cambridge Reference Sequence. Overall, only one synonymous mutation, which mapped to the NADH:ubiquinone oxidoreductase core subunit 5 gene, was observed in the tongue carcinoma sample from a single patient. A further 21 polymorphisms were identified, including six in the non-coding region (D-loop), five in Complex I, three in Complex III, two in Complex IV, two in Complex V and three in rRNA. In addition, mitochondrial microsatellite instability (mtMSI) was detected in 2/8 tongue carcinoma samples, and localized in the D310 region. These variations, particularly the polymorphisms and mtMSI, imply that the mitochondrial genome may be a hotspot of genome alteration in tongue cancer. Further investigation is expected to reveal the role of mtDNA alteration in TSCC development, as well as its clinical implications.
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Affiliation(s)
- Hong-Ying Shu
- Key Laboratory of Genetics and Birth Health of Hunan Province, Family Planning Institute of Hunan Province, Changsha, Hunan 410126, P.R. China
| | - Hong-Chao Li
- Department of Head and Neck Cancer (Oncoplastic Surgery), Hunan Cancer Hospital, Changsha, Hunan 410013, P.R. China
| | - Wan-Qin Xie
- Key Laboratory of Genetics and Birth Health of Hunan Province, Family Planning Institute of Hunan Province, Changsha, Hunan 410126, P.R. China
| | - Bin Ni
- Key Laboratory of Genetics and Birth Health of Hunan Province, Family Planning Institute of Hunan Province, Changsha, Hunan 410126, P.R. China
| | - Hai-Yan Zhou
- Key Laboratory of Genetics and Birth Health of Hunan Province, Family Planning Institute of Hunan Province, Changsha, Hunan 410126, P.R. China
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15
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HUANG Z, HAN YM, HONG XP, DUAN YJ, CHEN T, CHEN JR. Protective effect of electroacupuncture preconditioning at zúsānlĭ (足三里 ST36) on mitochondria in the intestinal ischemia/reperfusion injury. WORLD JOURNAL OF ACUPUNCTURE-MOXIBUSTION 2018. [DOI: 10.1016/j.wjam.2018.08.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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16
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Roest G, La Rovere RM, Bultynck G, Parys JB. IP 3 Receptor Properties and Function at Membrane Contact Sites. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 981:149-178. [PMID: 29594861 DOI: 10.1007/978-3-319-55858-5_7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) is a ubiquitously expressed Ca2+-release channel localized in the endoplasmic reticulum (ER). The intracellular Ca2+ signals originating from the activation of the IP3R regulate multiple cellular processes including the control of cell death versus cell survival via their action on apoptosis and autophagy. The exact role of the IP3Rs in these two processes does not only depend on their activity, which is modulated by the cytosolic composition (Ca2+, ATP, redox status, …) and by various types of regulatory proteins, including kinases and phosphatases as well as by a number of oncogenes and tumor suppressors, but also on their intracellular localization, especially at the ER-mitochondrial and ER-lysosomal interfaces. At these interfaces, Ca2+ microdomains are formed, in which the Ca2+ concentration is finely regulated by the different ER, mitochondrial and lysosomal Ca2+-transport systems and also depends on the functional and structural interactions existing between them. In this review, we therefore discuss the most recent insights in the role of Ca2+ signaling in general, and of the IP3R in particular, in the control of basal mitochondrial bioenergetics, apoptosis, and autophagy at the level of inter-organellar contact sites.
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Affiliation(s)
- Gemma Roest
- Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, KU Leuven, Leuven, Belgium
| | - Rita M La Rovere
- Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, KU Leuven, Leuven, Belgium
| | - Geert Bultynck
- Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, KU Leuven, Leuven, Belgium.
| | - Jan B Parys
- Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, KU Leuven, Leuven, Belgium.
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17
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Csordás G, Weaver D, Hajnóczky G. Endoplasmic Reticulum-Mitochondrial Contactology: Structure and Signaling Functions. Trends Cell Biol 2018; 28:523-540. [PMID: 29588129 DOI: 10.1016/j.tcb.2018.02.009] [Citation(s) in RCA: 363] [Impact Index Per Article: 60.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 02/23/2018] [Accepted: 02/23/2018] [Indexed: 02/08/2023]
Abstract
Interorganellar contacts are increasingly recognized as central to the control of cellular behavior. These contacts, which typically involve a small fraction of the endomembrane surface, are local communication hubs that resemble synapses. We propose the term contactology to denote the analysis of interorganellar contacts. Endoplasmic reticulum (ER) contacts with mitochondria were recognized several decades ago; major roles in ion and lipid transfer, signaling, and membrane dynamics have been established, while others continue to emerge. The functional diversity of ER-mitochondrial (ER-mito) contacts is mirrored in their structural heterogeneity, with subspecialization likely supported by multiple, different linker-forming protein structures. The nanoscale size of the contacts has made studying their structure, function, and dynamics difficult. This review focuses on the structure of the ER-mito contacts, methods for studying them, and the roles of contacts in Ca2+ and reactive oxygen species (ROS) signaling.
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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 19107, USA.
| | - David Weaver
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
| | - György Hajnóczky
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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18
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Drumm BT, Sung TS, Zheng H, Baker SA, Koh SD, Sanders KM. The effects of mitochondrial inhibitors on Ca 2+ signalling and electrical conductances required for pacemaking in interstitial cells of Cajal in the mouse small intestine. Cell Calcium 2018; 72:1-17. [PMID: 29748128 DOI: 10.1016/j.ceca.2018.01.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 01/26/2018] [Accepted: 01/27/2018] [Indexed: 01/16/2023]
Abstract
Interstitial cells of Cajal (ICC-MY) are pacemakers that generate and propagate electrical slow waves in gastrointestinal (GI) muscles. Slow waves appear to be generated by the release of Ca2+ from intracellular stores and activation of Ca2+-activated Cl- channels (Ano1). Conduction of slow waves to smooth muscle cells coordinates rhythmic contractions. Mitochondrial Ca2+ handling is currently thought to be critical for ICC pacemaking. Protonophores, inhibitors of the electron transport chain (FCCP, CCCP or antimycin) or mitochondrial Na+/Ca2+ exchange blockers inhibited slow waves in several GI muscles. Here we utilized Ca2+ imaging of ICC in small intestinal muscles in situ to determine the effects of mitochondrial drugs on Ca2+ transients in ICC. Muscles were obtained from mice expressing a genetically encoded Ca2+ indicator (GCaMP3) in ICC. FCCP, CCCP, antimycin, a uniporter blocker, Ru360, and a mitochondrial Na+/Ca2+ exchange inhibitor, CGP-37157 inhibited Ca2+ transients in ICC-MY. Effects were not due to depletion of ATP, as oligomycin did not affect Ca2+ transients. Patch-clamp experiments were performed to test the effects of the mitochondrial drugs on key pacemaker conductances, Ano1 and T-type Ca2+ (CaV3.2), in HEK293 cells. Antimycin blocked Ano1 and reduced CaV3.2 currents. CCCP blocked CaV3.2 current but did not affect Ano1 current. Ano1 and Cav3.2 currents were inhibited by CGP-37157. Inhibitory effects of mitochondrial drugs on slow waves and Ca2+ signalling in ICC can be explained by direct antagonism of key pacemaker conductances in ICC that generate and propagate slow waves. A direct obligatory role for mitochondria in pacemaker activity is therefore questionable.
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Affiliation(s)
- Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Tae S Sung
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Haifeng Zheng
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Sang D Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA.
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19
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Gonadal hormone modulation of intracellular calcium as a mechanism of neuroprotection. Front Neuroendocrinol 2016; 42:40-52. [PMID: 26930421 DOI: 10.1016/j.yfrne.2016.02.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 02/22/2016] [Accepted: 02/26/2016] [Indexed: 12/28/2022]
Abstract
Hormones have wide-ranging effects throughout the nervous system, including the ability interact with and modulate many aspects of intracellular calcium regulation and calcium signaling. Indeed, these interactions specifically may help to explain the often opposing or paradoxical effects of hormones, such as their ability to both promote and prevent neuronal cell death during development, as well as reduce or exacerbate damage following an insult or injury in adulthood. Here, we review the basic mechanisms underlying intracellular calcium regulation-perhaps the most dynamic and flexible of all signaling molecules-and discuss how gonadal hormones might manipulate these mechanisms to coordinate diverse cellular responses and achieve disparate outcomes. Additional future research that specifically addresses questions of sex and hormone effects on calcium signaling at different ages will be critical to understanding hormone-mediated neuroprotection.
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20
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Rouleau L, Antony AN, Bisetto S, Newberg A, Doria C, Levine M, Monti DA, Hoek JB. Synergistic effects of ascorbate and sorafenib in hepatocellular carcinoma: New insights into ascorbate cytotoxicity. Free Radic Biol Med 2016; 95:308-322. [PMID: 27036367 PMCID: PMC4867251 DOI: 10.1016/j.freeradbiomed.2016.03.031] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/24/2016] [Accepted: 03/28/2016] [Indexed: 12/15/2022]
Abstract
We investigated the mechanism of selective ascorbate-induced cytotoxicity in tumor cells, including Hep G2 cells, compared to primary hepatocytes. H2O2 formation was required for ascorbate cytotoxicity, as extracellular catalase treatment protected tumor cells. H2O2 generated by glucose oxidase treatment also caused cell killing, but treatment with a pharmacologic dose (5-20mM) of ascorbate was significantly more cytotoxic at comparable rates of H2O2 production, suggesting that ascorbate enhanced H2O2 cytotoxicity. This was further supported by the finding that ascorbate at a non-cytotoxic dose (1mM) enhanced cell killing caused by glucose oxidase. Consistent with this conclusion, ascorbate treatment caused deregulation of cellular calcium homeostasis, resulting in massive mitochondrial calcium accumulation. Ascorbate acted synergistically with the chemotherapeutic sorafenib in killing Hep G2 cells, but not primary hepatocytes, suggesting adjuvant ascorbate treatment can broaden sorafenib's therapeutic range. Sorafenib caused mitochondrial depolarization and prevented mitochondrial calcium sequestration. Subsequent ascorbate addition further deregulated cellular calcium homeostasis promoting cell death. Additionally, we present the case of a patient with hepatocellular carcinoma (HCC) who had prolonged regression of a rib metastasis upon combination treatment with ascorbate and sorafenib, indicating that these studies have direct clinical relevance.
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Affiliation(s)
- Lauren Rouleau
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Anil Noronha Antony
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Sara Bisetto
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Andrew Newberg
- Jefferson-Myrna Brind Center of Integrative Medicine, Thomas Jefferson University Hospital, Philadelphia, PA 19107, USA
| | - Cataldo Doria
- Division of Transplantation, Liver Tumor Center, Thomas Jefferson University Hospital, Philadelphia, PA 19107, USA
| | - Mark Levine
- Molecular and Clinical Nutrition Section, Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Daniel A Monti
- Jefferson-Myrna Brind Center of Integrative Medicine, Thomas Jefferson University Hospital, Philadelphia, PA 19107, USA
| | - Jan B Hoek
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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21
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Guida BS, Garcia-Pichel F. Extreme cellular adaptations and cell differentiation required by a cyanobacterium for carbonate excavation. Proc Natl Acad Sci U S A 2016; 113:5712-7. [PMID: 27140633 PMCID: PMC4878501 DOI: 10.1073/pnas.1524687113] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Some cyanobacteria, known as euendoliths, excavate and grow into calcium carbonates, with their activity leading to significant marine and terrestrial carbonate erosion and to deleterious effects on coral reef and bivalve ecology. Despite their environmental relevance, the mechanisms by which they can bore have remained elusive and paradoxical, in that, as oxygenic phototrophs, cyanobacteria tend to alkalinize their surroundings, which will encourage carbonate precipitation, not dissolution. Therefore, cyanobacteria must rely on unique adaptations to bore. Studies with the filamentous euendolith, Mastigocoleus testarum, indicated that excavation requires both cellular energy and transcellular calcium transport, mediated by P-type ATPases, but the cellular basis for this phenomenon remains obscure. We present evidence that excavation in M. testarum involves two unique cellular adaptations. Long-range calcium transport is based on active pumping at multiple cells along boring filaments, orchestrated by the preferential localization of calcium ATPases at one cell pole, in a ring pattern, facing the cross-walls, and by repeating this placement and polarity, a pattern that breaks at branching and apical cells. In addition, M. testarum differentiates specialized cells we call calcicytes, that which accumulate calcium at concentrations more than 500-fold those found in other cyanobacteria, concomitantly and drastically lowering photosynthetic pigments and enduring severe cytoplasmatic alkalinization. Calcicytes occur commonly, but not exclusively, in apical parts of the filaments distal to the excavation front. We suggest that calcicytes allow for fast calcium flow at low, nontoxic concentrations through undifferentiated cells by providing buffering storage for excess calcium before final excretion to the outside medium.
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22
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Abstract
In the last 5 years, most of the molecules that control mitochondrial Ca(2+) homeostasis have been finally identified. Mitochondrial Ca(2+) uptake is mediated by the Mitochondrial Calcium Uniporter (MCU) complex, a macromolecular structure that guarantees Ca(2+) accumulation inside mitochondrial matrix upon increases in cytosolic Ca(2+). Conversely, Ca(2+) release is under the control of the Na(+)/Ca(2+) exchanger, encoded by the NCLX gene, and of a H(+)/Ca(2+) antiporter, whose identity is still debated. The low affinity of the MCU complex, coupled to the activity of the efflux systems, protects cells from continuous futile cycles of Ca(2+) across the inner mitochondrial membrane and consequent massive energy dissipation. In this review, we discuss the basic principles that govern mitochondrial Ca(2+) homeostasis and the methods used to investigate the dynamics of Ca(2+) concentration within the organelles. We discuss the functional and structural role of the different molecules involved in mitochondrial Ca(2+) handling and their pathophysiological role.
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Affiliation(s)
- Diego De Stefani
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , ,
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , , .,National Research Council (CNR) Neuroscience Institute, 35121 Padova, Italy
| | - Tullio Pozzan
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , , .,National Research Council (CNR) Neuroscience Institute, 35121 Padova, Italy.,Venetian Institute of Molecular Medicine, 35121 Padova, Italy
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23
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Pérez-Gordones M, Serrano M, Rojas H, Martínez J, Uzcanga G, Mendoza M. Presence of a thapsigargin-sensitive calcium pump in Trypanosoma evansi: Immunological, physiological, molecular and structural evidences. Exp Parasitol 2015; 159:107-17. [DOI: 10.1016/j.exppara.2015.08.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 07/28/2015] [Accepted: 08/16/2015] [Indexed: 10/23/2022]
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24
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Bánsághi S, Golenár T, Madesh M, Csordás G, RamachandraRao S, Sharma K, Yule DI, Joseph SK, Hajnóczky G. Isoform- and species-specific control of inositol 1,4,5-trisphosphate (IP3) receptors by reactive oxygen species. J Biol Chem 2014; 289:8170-81. [PMID: 24469450 DOI: 10.1074/jbc.m113.504159] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Reactive oxygen species (ROS) stimulate cytoplasmic [Ca(2+)] ([Ca(2+)]c) signaling, but the exact role of the IP3 receptors (IP3R) in this process remains unclear. IP3Rs serve as a potential target of ROS produced by both ER and mitochondrial enzymes, which might locally expose IP3Rs at the ER-mitochondrial associations. Also, IP3Rs contain multiple reactive thiols, common molecular targets of ROS. Therefore, we have examined the effect of superoxide anion (O2) on IP3R-mediated Ca(2+) signaling. In human HepG2, rat RBL-2H3, and chicken DT40 cells, we observed [Ca(2+)]c spikes and frequency-modulated oscillations evoked by a O2 donor, xanthine (X) + xanthine oxidase (XO), dose-dependently. The [Ca(2+)]c signal was mediated by ER Ca(2+) mobilization. X+XO added to permeabilized cells promoted the [Ca(2+)]c rise evoked by submaximal doses of IP3, indicating that O2 directly sensitizes IP3R-mediated Ca(2+) release. In response to X+XO, DT40 cells lacking two of three IP3R isoforms (DKO) expressing either type 1 (DKO1) or type 2 IP3Rs (DKO2) showed a [Ca(2+)]c signal, whereas DKO expressing type 3 IP3R (DKO3) did not. By contrast, IgM that stimulates IP3 formation, elicited a [Ca(2+)]c signal in every DKO. X+XO also facilitated the Ca(2+) release evoked by submaximal IP3 in permeabilized DKO1 and DKO2 but was ineffective in DKO3 or in DT40 lacking every IP3R (TKO). However, X+XO could also facilitate the effect of suboptimal IP3 in TKO transfected with rat IP3R3. Although in silico studies failed to identify a thiol missing in the chicken IP3R3, an X+XO-induced redox change was documented only in the rat IP3R3. Thus, ROS seem to specifically sensitize IP3Rs through a thiol group(s) within the IP3R, which is probably inaccessible in the chicken IP3R3.
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Affiliation(s)
- Száva Bánsághi
- From the MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
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25
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Joseph N, Reicher B, Barda-Saad M. The calcium feedback loop and T cell activation: how cytoskeleton networks control intracellular calcium flux. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:557-68. [PMID: 23860253 DOI: 10.1016/j.bbamem.2013.07.009] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 06/30/2013] [Accepted: 07/08/2013] [Indexed: 12/31/2022]
Abstract
During T cell activation, the engagement of a T cell with an antigen-presenting cell (APC) results in rapid cytoskeletal rearrangements and a dramatic increase of intracellular calcium (Ca(2+)) concentration, downstream to T cell antigen receptor (TCR) ligation. These events facilitate the organization of an immunological synapse (IS), which supports the redistribution of receptors, signaling molecules and organelles towards the T cell-APC interface to induce downstream signaling events, ultimately supporting T cell effector functions. Thus, Ca(2+) signaling and cytoskeleton rearrangements are essential for T cell activation and T cell-dependent immune response. Rapid release of Ca(2+) from intracellular stores, e.g. the endoplasmic reticulum (ER), triggers the opening of Ca(2+) release-activated Ca(2+) (CRAC) channels, residing in the plasma membrane. These channels facilitate a sustained influx of extracellular Ca(2+) across the plasma membrane in a process termed store-operated Ca(2+) entry (SOCE). Because CRAC channels are themselves inhibited by Ca(2+) ions, additional factors are suggested to enable the sustained Ca(2+) influx required for T cell function. Among these factors, we focus here on the contribution of the actin and microtubule cytoskeleton. The TCR-mediated increase in intracellular Ca(2+) evokes a rapid cytoskeleton-dependent polarization, which involves actin cytoskeleton rearrangements and microtubule-organizing center (MTOC) reorientation. Here, we review the molecular mechanisms of Ca(2+) flux and cytoskeletal rearrangements, and further describe the way by which the cytoskeletal networks feedback to Ca(2+) signaling by controlling the spatial and temporal distribution of Ca(2+) sources and sinks, modulating TCR-dependent Ca(2+) signals, which are required for an appropriate T cell response. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé.
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Affiliation(s)
- Noah Joseph
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Barak Reicher
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Mira Barda-Saad
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel.
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26
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Waldeck-Weiermair M, Deak AT, Groschner LN, Alam MR, Jean-Quartier C, Malli R, Graier WF. Molecularly distinct routes of mitochondrial Ca2+ uptake are activated depending on the activity of the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA). J Biol Chem 2013; 288:15367-79. [PMID: 23592775 PMCID: PMC3663555 DOI: 10.1074/jbc.m113.462259] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The transfer of Ca2+ across the inner mitochondrial membrane is an important physiological process linked to the regulation of metabolism, signal transduction, and cell death. While the definite molecular composition of mitochondrial Ca2+ uptake sites remains unknown, several proteins of the inner mitochondrial membrane, that are likely to accomplish mitochondrial Ca2+ fluxes, have been described: the novel uncoupling proteins 2 and 3, the leucine zipper-EF-hand containing transmembrane protein 1 and the mitochondrial calcium uniporter. It is unclear whether these proteins contribute to one unique mitochondrial Ca2+ uptake pathway or establish distinct routes for mitochondrial Ca2+ sequestration. In this study, we show that a modulation of Ca2+ release from the endoplasmic reticulum by inhibition of the sarco/endoplasmatic reticulum ATPase modifies cytosolic Ca2+ signals and consequently switches mitochondrial Ca2+ uptake from an uncoupling protein 3- and mitochondrial calcium uniporter-dependent, but leucine zipper-EF-hand containing transmembrane protein 1-independent to a leucine zipper-EF-hand containing transmembrane protein 1- and mitochondrial calcium uniporter-mediated, but uncoupling protein 3-independent pathway. Thus, the activity of sarco/endoplasmatic reticulum ATPase is significant for the mode of mitochondrial Ca2+ sequestration and determines which mitochondrial proteins might actually accomplish the transfer of Ca2+ across the inner mitochondrial membrane. Moreover, our findings herein support the existence of distinct mitochondrial Ca2+ uptake routes that might be essential to ensure an efficient ion transfer into mitochondria despite heterogeneous cytosolic Ca2+ rises.
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Affiliation(s)
- Markus Waldeck-Weiermair
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010 Graz, Austria
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27
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Bhanumathy C, da Fonseca PCA, Morris EP, Joseph SK. Identification of functionally critical residues in the channel domain of inositol trisphosphate receptors. J Biol Chem 2012; 287:43674-84. [PMID: 23086950 PMCID: PMC3527953 DOI: 10.1074/jbc.m112.415786] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
We have combined alanine mutagenesis and functional assays to identify amino acid residues in the channel domain that are critical for inositol 1,4,5-trisphosphate receptor (IP(3)R) channel function. The residues selected were highly conserved in all three IP(3)R isoforms and were located in the cytosolic end of the S6 pore-lining helix and proximal portion of the C-tail. Two adjacent hydrophobic amino acids (Ile-2588 and Ile-2589) at the putative cytosolic interface of the S6 helix inactivated channel function and could be candidates for the channel gate. Of five negatively charged residues mutated, none completely eliminated channel function. Of five positively charged residues mutated, only one inactivated the channel (Arg-2596). In addition to the previously identified role of a pair of cysteines in the C-tail (Cys-2610 and Cys-2613), a pair of highly conserved histidines (His-2630 and His-2635) were also essential for channel function. Expression of the H2630A and H2635A mutants (but not R2596A) produced receptors with destabilized interactions between the N-terminal fragment and the channel domain. A previously unrecognized association between the cytosolic C-tail and the TM 4,5-loop was demonstrated using GST pulldown assays. However, none of the mutations in the C-tail interfered with this interaction or altered the ability of the C-tail to assemble into dimers. Our present findings and recent information on IP(3)R structure from electron microscopy and crystallography are incorporated into a revised model of channel gating.
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MESH Headings
- Amino Acid Substitution
- Animals
- COS Cells
- Chlorocebus aethiops
- HEK293 Cells
- Humans
- Inositol 1,4,5-Trisphosphate Receptors/chemistry
- Inositol 1,4,5-Trisphosphate Receptors/genetics
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Ion Channel Gating/physiology
- Models, Molecular
- Mutation, Missense
- Protein Multimerization/physiology
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Rats
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Affiliation(s)
- Cunnigaiper Bhanumathy
- From the Department of Pathology and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 and
| | - Paula C. A. da Fonseca
- the Institute for Cancer Research, Chester Beatty Laboratories, London, SW3 6JB, United Kingdom
| | - Edward P. Morris
- the Institute for Cancer Research, Chester Beatty Laboratories, London, SW3 6JB, United Kingdom
| | - Suresh K. Joseph
- From the Department of Pathology and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 and
- To whom correspondence should be addressed: Dept. of Pathology & Cell Biology, Rm. 230A JAH, 1020 Locust St., Philadelphia, PA 19107. Tel.: 215-503-1222; E-mail:
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Carreras-Sureda A, Cantero-Recasens G, Rubio-Moscardo F, Kiefer K, Peinelt C, Niemeyer BA, Valverde MA, Vicente R. ORMDL3 modulates store-operated calcium entry and lymphocyte activation. Hum Mol Genet 2012; 22:519-30. [PMID: 23100328 DOI: 10.1093/hmg/dds450] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
T lymphocytes rely on a Ca(2+) signal known as store-operated calcium entry (SOCE) for their activation. This Ca(2+) signal is generated by activation of a T-cell receptor, depletion of endoplasmic reticulum (ER) Ca(2+) stores and activation of Ca(2+) release-activated Ca(2+) currents (I(CRAC)). Here, we report that the ER protein orosomucoid like 3 (ORMDL3), the product of the ORMDL3 gene associated with several autoimmune and/or inflammatory diseases, negatively modulates I(CRAC), SOCE, nuclear factor of activated T cells nuclear translocation and interleukin-2 production. ORMDL3 inhibits the Ca(2+) influx mechanism at the outer mitochondrial membrane, resulting in a Ca(2+)-dependent inhibition of I(CRAC) and reduced SOCE. The effect of ORMDL3 could be mimicked by interventions that decreased mitochondrial Ca(2+) influx and reverted by buffering of cytosolic Ca(2+) or activation of mitochondrial Ca(2+) influx. In conclusion, ORMDL3 modifies key steps in the process of T-lymphocyte activation, providing a functional link between the genetic associations of the ORMDL3 gene with autoimmune and/or inflammatory diseases.
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Affiliation(s)
- Amado Carreras-Sureda
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona 08003, Spain
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Csordás G, Várnai P, Golenár T, Sheu SS, Hajnóczky G. Calcium transport across the inner mitochondrial membrane: molecular mechanisms and pharmacology. Mol Cell Endocrinol 2012; 353:109-13. [PMID: 22123069 PMCID: PMC3295916 DOI: 10.1016/j.mce.2011.11.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 11/10/2011] [Accepted: 11/10/2011] [Indexed: 01/21/2023]
Abstract
Growing evidence supports that mitochondrial calcium uptake is important for cell metabolism, signaling and survival. However, both the molecular nature of the mitochondrial Ca(2+) transport sites and the calcium signals they respond to remained elusive. Recent RNA interference studies have identified new candidate proteins for Ca(2+) transport across the inner mitochondrial membrane, including LETM1, MCU, MICU1 and NCLX. The sensitivity of these factors to several drugs has been tested and in parallel, some new inhibitors of mitochondrial Ca(2+) uptake have been described. This paper provides an update on the pharmacological aspects of the molecular mechanisms of the inner mitochondrial membrane Ca(2+) transport.
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Affiliation(s)
- György Csordás
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Peter Várnai
- Department of Physiology, Semmelweis University Budapest, Hungary
| | - Tünde Golenár
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Shey-Shing Sheu
- Center for Translational Medicine, Thomas Jefferson University, Philadelphia, PA 19107
| | - György Hajnóczky
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107
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30
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De Marchi U, Castelbou C, Demaurex N. Uncoupling protein 3 (UCP3) modulates the activity of Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) by decreasing mitochondrial ATP production. J Biol Chem 2011; 286:32533-41. [PMID: 21775425 PMCID: PMC3173197 DOI: 10.1074/jbc.m110.216044] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 06/17/2011] [Indexed: 12/17/2022] Open
Abstract
The uncoupling proteins UCP2 and UCP3 have been postulated to catalyze Ca(2+) entry across the inner membrane of mitochondria, but this proposal is disputed, and other, unrelated proteins have since been identified as the mitochondrial Ca(2+) uniporter. To clarify the role of UCPs in mitochondrial Ca(2+) handling, we down-regulated the expression of the only uncoupling protein of HeLa cells, UCP3, and measured Ca(2+) and ATP levels in the cytosol and in organelles with genetically encoded probes. UCP3 silencing did not alter mitochondrial Ca(2+) uptake in permeabilized cells. In intact cells, however, UCP3 depletion increased mitochondrial ATP production and strongly reduced the cytosolic and mitochondrial Ca(2+) elevations evoked by histamine. The reduced Ca(2+) elevations were due to inhibition of store-operated Ca(2+) entry and reduced depletion of endoplasmic reticulum (ER) Ca(2+) stores. UCP3 depletion accelerated the ER Ca(2+) refilling kinetics, indicating that the activity of sarco/endoplasmic reticulum Ca(2+) (SERCA) pumps was increased. Accordingly, SERCA inhibitors reversed the effects of UCP3 depletion on cytosolic, ER, and mitochondrial Ca(2+) responses. Our results indicate that UCP3 is not a mitochondrial Ca(2+) uniporter and that it instead negatively modulates the activity of SERCA by limiting mitochondrial ATP production. The effects of UCP3 on mitochondrial Ca(2+) thus reflect metabolic alterations that impact on cellular Ca(2+) homeostasis. The sensitivity of SERCA to mitochondrial ATP production suggests that mitochondria control the local ATP availability at ER Ca(2+) uptake and release sites.
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Affiliation(s)
- Umberto De Marchi
- From the Department of Cell Physiology and Metabolism, University of Geneva, rue Michel-Servet, 1, CH-1211 Genève, Switzerland
| | - Cyril Castelbou
- From the Department of Cell Physiology and Metabolism, University of Geneva, rue Michel-Servet, 1, CH-1211 Genève, Switzerland
| | - Nicolas Demaurex
- From the Department of Cell Physiology and Metabolism, University of Geneva, rue Michel-Servet, 1, CH-1211 Genève, Switzerland
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31
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Yi J, Ma C, Li Y, Weisleder N, Ríos E, Ma J, Zhou J. Mitochondrial calcium uptake regulates rapid calcium transients in skeletal muscle during excitation-contraction (E-C) coupling. J Biol Chem 2011; 286:32436-43. [PMID: 21795684 DOI: 10.1074/jbc.m110.217711] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Defective coupling between sarcoplasmic reticulum and mitochondria during control of intracellular Ca(2+) signaling has been implicated in the progression of neuromuscular diseases. Our previous study showed that skeletal muscles derived from an amyotrophic lateral sclerosis (ALS) mouse model displayed segmental loss of mitochondrial function that was coupled with elevated and uncontrolled sarcoplasmic reticulum Ca(2+) release activity. The localized mitochondrial defect in the ALS muscle allows for examination of the mitochondrial contribution to Ca(2+) removal during excitation-contraction coupling by comparing Ca(2+) transients in regions with normal and defective mitochondria in the same muscle fiber. Here we show that Ca(2+) transients elicited by membrane depolarization in fiber segments with defective mitochondria display an ~10% increased amplitude. These regional differences in Ca(2+) transients were abolished by the application of 1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, a fast Ca(2+) chelator that reduces mitochondrial Ca(2+) uptake. Using a mitochondria-targeted Ca(2+) biosensor (mt11-YC3.6) expressed in ALS muscle fibers, we monitored the dynamic change of mitochondrial Ca(2+) levels during voltage-induced Ca(2+) release and detected a reduced Ca(2+) uptake by mitochondria in the fiber segment with defective mitochondria, which mirrored the elevated Ca(2+) transients in the cytosol. Our study constitutes a direct demonstration of the importance of mitochondria in shaping the cytosolic Ca(2+) signaling in skeletal muscle during excitation-contraction coupling and establishes that malfunction of this mechanism may contribute to neuromuscular degeneration in ALS.
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Affiliation(s)
- Jianxun Yi
- Department of Molecular Biophysics and Physiology, Rush University School of Medicine, Chicago, Illinois 60612, USA
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32
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Ma HT, Beaven MA. Regulators of Ca(2+) signaling in mast cells: potential targets for treatment of mast cell-related diseases? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 716:62-90. [PMID: 21713652 DOI: 10.1007/978-1-4419-9533-9_5] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A calcium signal is essential for degranulation, generation of eicosanoids and optimal production of cytokines in mast cells in response to antigen and other stimulants. The signal is initiated by phospholipase C-mediated production of inositol1,4,5-trisphosphate resulting in release of stored Ca(2+) from the endoplasmic reticulum (ER) and Golgi. Depletion of these stores activates influx of extracellular Ca(2+), usually referred to as store-operated calcium entry (SOCE), through the interaction of the Ca(2+)-sensor, stromal interacting molecule-1 (STIM1 ), in ER with Orai1(CRACM1) and transient receptor potential canonical (TRPC) channel proteins in the plasma membrane (PM). This interaction is enabled by microtubular-directed reorganization of ER to form ER/PM contact points or "punctae" in which STIM1 and channel proteins colocalize. The ensuing influx of Ca(2+) replenishes Ca(2+) stores and sustains elevated levels of cytosolic Ca(2+) ions-the obligatory signal for mast-cell activation. In addition, the signal can acquire spatial and dynamic characteristics (e.g., calcium puffs, waves, oscillations) that encode signals for specific functional outputs. This is achieved by coordinated regulation of Ca(2+) fluxes through ATP-dependent Ca(2+)-pumps and ion exchangers in mitochondria, ER and PM. As discussed in this chapter, studies in mast cells revealed much about the mechanisms described above but little about allergic and autoimmune diseases although studies in other types of cells have exposed genetic defects that lead to aberrant calcium signaling in immune diseases. Pharmacologic agents that inhibit or activate the regulatory components of calcium signaling in mast cells are also discussed along with the prospects for development of novel SOCE inhibitors that may prove beneficial in the treatment inflammatory mast-cell related diseases.
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Affiliation(s)
- Hong-Tao Ma
- Laboratory of Molecular Immunology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
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33
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Fujimoto M, Hayashi T. New Insights into the Role of Mitochondria-Associated Endoplasmic Reticulum Membrane. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 292:73-117. [DOI: 10.1016/b978-0-12-386033-0.00002-5] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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34
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Decuypere JP, Monaco G, Bultynck G, Missiaen L, De Smedt H, Parys JB. The IP(3) receptor-mitochondria connection in apoptosis and autophagy. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:1003-13. [PMID: 21146562 DOI: 10.1016/j.bbamcr.2010.11.023] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 11/24/2010] [Accepted: 11/25/2010] [Indexed: 01/08/2023]
Abstract
The amount of Ca(2+) taken up in the mitochondrial matrix is a crucial determinant of cell fate; it plays a decisive role in the choice of the cell between life and death. The Ca(2+) ions mainly originate from the inositol 1,4,5-trisphosphate (IP(3))-sensitive Ca(2+) stores of the endoplasmic reticulum (ER). The uptake of these Ca(2+) ions in the mitochondria depends on the functional properties and the subcellular localization of the IP(3) receptor (IP(3)R) in discrete domains near the mitochondria. To allow for an efficient transfer of the Ca(2+) ions from the ER to the mitochondria, structural interactions between IP(3)Rs and mitochondria are needed. This review will focus on the key proteins involved in these interactions, how they are regulated, and what are their physiological roles in apoptosis, necrosis and autophagy. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.
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Affiliation(s)
- Jean-Paul Decuypere
- Laboratory of Molecular and Cellular Signalling, Dept. Molecular and Cellular, campus Gasthuisberg O/N1 K.U.Leuven, Bus 802, B-3000 Leuven, Belgium
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35
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Simmen T, Lynes EM, Gesson K, Thomas G. Oxidative protein folding in the endoplasmic reticulum: tight links to the mitochondria-associated membrane (MAM). BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1465-73. [PMID: 20430008 DOI: 10.1016/j.bbamem.2010.04.009] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 04/15/2010] [Accepted: 04/16/2010] [Indexed: 12/18/2022]
Abstract
The production of secretory proteins at the ER (endoplasmic reticulum) depends on a ready supply of energy and metabolites as well as the close monitoring of the chemical conditions that favor oxidative protein folding. ER oxidoreductases and chaperones fold nascent proteins into their export-competent three-dimensional structure. Interference with these protein folding enzymes leads to the accumulation of unfolded proteins within the ER lumen, causing an acute organellar stress that triggers the UPR (unfolded protein response). The UPR increases the transcription of ER chaperones commensurate with the load of newly synthesized proteins and can protect the cell from ER stress. Persistant stress, however, can force the UPR to commit cells to undergo apoptotic cell death, which requires the emptying of ER calcium stores. Conversely, a continuous ebb and flow of calcium occurs between the ER and mitochondria during resting conditions on a domain of the ER that forms close contacts with mitochondria, the MAM (mitochondria-associated membrane). On the MAM, ER folding chaperones such as calnexin and calreticulin and oxidoreductases such as ERp44, ERp57 and Ero1alpha regulate calcium flux from the ER through reversible, calcium and redox-dependent interactions with IP3Rs (inositol 1,4,5-trisphophate receptors) and with SERCAs (sarcoplasmic/endoplasmic reticulum calcium ATPases). During apoptosis progression and depending on the identity of the ER chaperone and oxidoreductase, these interactions increase or decrease, suggesting that the extent of MAM targeting of ER chaperones and oxidoreductases could shift the readout of ER-mitochondria calcium exchange from housekeeping to apoptotic. However, little is known about the cytosolic factors that mediate the on/off interactions between ER chaperones and oxidoreductases with ER calcium channels and pumps. One candidate regulator is the multi-functional molecule PACS-2 (phosphofurin acidic cluster sorting protein-2). Recent studies suggest that PACS-2 mediates localization of a mobile pool of calnexin to the MAM in addition to regulating homeostatic ER calcium signaling as well as MAM integrity. Together, these findings suggest that cytosolic, membrane and lumenal proteins combine to form a two-way switch that determines the rate of protein secretion by providing ions and metabolites and that appears to participate in the pro-apoptotic ER-mitochondria calcium transfer.
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Affiliation(s)
- Thomas Simmen
- Faculty of Medicine and Dentistry, School of Molecular and Systems Medicine, Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada.
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36
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Yap SV, Vafiadaki E, Strong J, Kontrogianni-Konstantopoulos A. HAX-1: a multifaceted antiapoptotic protein localizing in the mitochondria and the sarcoplasmic reticulum of striated muscle cells. J Mol Cell Cardiol 2009; 48:1266-79. [PMID: 19913549 DOI: 10.1016/j.yjmcc.2009.10.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 10/23/2009] [Accepted: 10/30/2009] [Indexed: 11/27/2022]
Abstract
HAX-1 comprises a family of ubiquitously expressed proteins with antiapoptotic properties. In the current study, we investigated HAX-1's temporospatial distribution in rat striated muscles during development and in adulthood. In cardiocytes, HAX-1 is organized at the level of Z-disks throughout embryogenesis and adulthood; however, in skeletal myofibers, it is in register with M-bands during embryonic and early postnatal life and Z-disks during late postnatal and adult life. Immunoelectron microscopy and subcellular fractionation demonstrated that HAX-1 proteins localize at the mitochondrial and sarcoplasmic reticulum (SR) membranes, as well as at sites where the two are closely apposed. Variants I and II selectively concentrate in the mitochondrial membranes, whereas variants III, IV, and V localize in both organelles, albeit to varying extents. Deletion analysis combined with cellular transfections indicated that elimination of HAX-1's NH(2)-terminus abolishes its mitochondrial targeting and attenuates its antiapoptotic capacity, while removal of its binding site for the SR protein phospholamban (PLN) prevents its translocation to the SR. Consistent with this, HAX-1 is preferentially lost from the SR of PLN-deficient hearts. Our findings are the first to present a comprehensive characterization of HAX-1's expression in striated muscles and to provide insights on the mechanisms through which it may modulate apoptosis.
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Affiliation(s)
- Solomon V Yap
- University of Maryland, School of Medicine, Department of Biochemistry and Molecular Biology, Baltimore, MD 21201, USA
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37
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Gunter TE, Sheu SS. Characteristics and possible functions of mitochondrial Ca(2+) transport mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1787:1291-308. [PMID: 19161975 PMCID: PMC2730425 DOI: 10.1016/j.bbabio.2008.12.011] [Citation(s) in RCA: 154] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 12/22/2008] [Accepted: 12/29/2008] [Indexed: 02/07/2023]
Abstract
Mitochondria produce around 92% of the ATP used in the typical animal cell by oxidative phosphorylation using energy from their electrochemical proton gradient. Intramitochondrial free Ca(2+) concentration ([Ca(2+)](m)) has been found to be an important component of control of the rate of this ATP production. In addition, [Ca(2+)](m) also controls the opening of a large pore in the inner mitochondrial membrane, the permeability transition pore (PTP), which plays a role in mitochondrial control of programmed cell death or apoptosis. Therefore, [Ca(2+)](m) can control whether the cell has sufficient ATP to fulfill its functions and survive or is condemned to death. Ca(2+) is also one of the most important second messengers within the cytosol, signaling changes in cellular response through Ca(2+) pulses or transients. Mitochondria can also sequester Ca(2+) from these transients so as to modify the shape of Ca(2+) signaling transients or control their location within the cell. All of this is controlled by the action of four or five mitochondrial Ca(2+) transport mechanisms and the PTP. The characteristics of these mechanisms of Ca(2+) transport and a discussion of how they might function are described in this paper.
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Affiliation(s)
- Thomas E Gunter
- Department of Biochemistry and Biophysics and Mitochondrial Research and Innovation Group, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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38
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Ruiz A, Matute C, Alberdi E. Endoplasmic reticulum Ca(2+) release through ryanodine and IP(3) receptors contributes to neuronal excitotoxicity. Cell Calcium 2009; 46:273-81. [PMID: 19747726 DOI: 10.1016/j.ceca.2009.08.005] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Accepted: 08/20/2009] [Indexed: 01/02/2023]
Abstract
Overactivation of ionotropic glutamate receptors induces a Ca(2+) overload into the cytoplasm that leads neurons to excitotoxic death, a process that has been linked to several neurodegenerative disorders. While the role of mitochondria and its involvement in excitotoxicity have been widely studied, the contribution of endoplasmic reticulum (ER), another crucial intracellular store in maintaining Ca(2+) homeostasis, is not fully understood. In this study, we analyzed the contribution of ER-Ca(2+) release through ryanodine (RyR) and IP(3) (IP(3)R) receptors to a neuronal in vitro model of excitotoxicity. NMDA induced a dose-dependent neuronal death, which was significantly decreased by ER-Ca(2+) release inhibitors in cortical neurons as well as in organotypic slices. Furthermore, ryanodine and 2APB, RyR and IP(3)R inhibitors respectively, attenuated NMDA-triggered intracellular Ca(2+) increase and oxidative stress, whereas 2APB reduced mitochondrial membrane depolarization and caspase-3 cleavage. Consistent with ER-Ca(2+) homeostasis disruption, we observed that NMDA-induced ER stress, characterized here by eIF2alpha phosphorylation and over-expression of GRP chaperones which were regulated by ER-Ca(2+) release inhibitors. These results demonstrate that Ca(2+) release from ER contributes to neuronal death by both promoting mitochondrial dysfunction and inducing specific stress and apoptosis pathways during excitotoxicity.
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Affiliation(s)
- Asier Ruiz
- Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas (CIBERNED), Spain
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39
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Abstract
Calcium signals mediate diverse cellular functions in immunological cells. Early studies with mast cells, then a preeminent model for studying Ca2+-dependent exocytosis, revealed several basic features of calcium signaling in non-electrically excitable cells. Subsequent studies in these and other cells further defined the basic processes such as inositol 1,4,5-trisphosphate-mediated release of Ca2+ from Ca2+ stores in the endoplasmic reticulum (ER); coupling of ER store depletion to influx of external Ca2+ through a calcium-release activated calcium (CRAC) channel now attributed to the interaction of the ER Ca2+ sensor, stromal interacting molecule-1 (STIM1), with a unique Ca2+-channel protein, Orai1/CRACM1, and subsequent uptake of excess Ca2+ into ER and mitochondria through ATP-dependent Ca2+ pumps. In addition, transient receptor potential channels and ion exchangers also contribute to the generation of calcium signals that may be global or have dynamic (e.g., waves and oscillations) and spatial resolution for specific functional readouts. This review discusses past and recent developments in this field of research, the pharmacologic agents that have assisted in these endeavors, and the mast cell as an exemplar for sorting out how calcium signals may regulate multiple outputs in a single cell.
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Affiliation(s)
- Hong-Tao Ma
- Laboratory of Molecular Immunology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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40
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Lordan S, O'Brien NM, Mackrill JJ. The role of calcium in apoptosis induced by 7β-hydroxycholesterol and cholesterol-5β,6β-epoxide. J Biochem Mol Toxicol 2009; 23:324-32. [DOI: 10.1002/jbt.20295] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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41
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Laskowski AI, Medler KF. Sodium-calcium exchangers contribute to the regulation of cytosolic calcium levels in mouse taste cells. J Physiol 2009; 587:4077-89. [PMID: 19581381 DOI: 10.1113/jphysiol.2009.173567] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Taste cells use multiple signalling mechanisms to generate unique calcium responses to distinct taste stimuli. Some taste stimuli activate G-protein coupled receptors (GPCRs) that cause calcium release from intracellular stores while other stimuli depolarize taste cells to cause calcium influx through voltage-gated calcium channels (VGCCs). We recently demonstrated that a constitutive calcium influx exists in taste cells that is regulated by mitochondrial calcium transport and that the magnitude of this calcium influx correlates with the signalling mechanisms used by the taste cells. In this study, we used calcium imaging to determine that sodium-calcium exchangers (NCXs) also routinely contribute to the regulation of basal cytosolic calcium and that their relative role correlates with the signalling mechanisms used by the taste cells. RT-PCR analysis revealed that multiple NCXs and sodium-calcium-potassium exchangers (NCKXs) are expressed in taste cells. Thus, a dynamic relationship exists between calcium leak channels and calcium regulatory mechanisms in taste cells that functions to keep cytosolic calcium levels in the appropriate range for cell function.
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Affiliation(s)
- Agnieszka I Laskowski
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
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42
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MAM: more than just a housekeeper. Trends Cell Biol 2009; 19:81-8. [PMID: 19144519 DOI: 10.1016/j.tcb.2008.12.002] [Citation(s) in RCA: 576] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 12/01/2008] [Accepted: 12/02/2008] [Indexed: 11/23/2022]
Abstract
The physical association between the endoplasmic reticulum (ER) and mitochondria, which is known as the mitochondria-associated ER membrane (MAM), has important roles in various cellular 'housekeeping' functions including the non-vesicular transports of phospholipids. It has recently become clear that the MAM also enables highly efficient transmission of Ca(2+) from the ER to mitochondria to stimulate oxidative metabolism and, conversely, might enable the metabolically energized mitochondria to regulate the ER Ca(2+) homeostasis. Recent studies have shed light on molecular chaperones such as calnexin, calreticulin, ERp44, ERp57, grp75 and the sigma-1 receptor at the MAM, which regulate the association between the two organelles. The MAM thus integrates signal transduction with metabolic pathways to regulate the communication and functional interactions between the ER and mitochondrion.
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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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Roy SS, Hajnóczky G. Calcium, mitochondria and apoptosis studied by fluorescence measurements. Methods 2008; 46:213-23. [PMID: 18948203 DOI: 10.1016/j.ymeth.2008.09.024] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2008] [Accepted: 09/12/2008] [Indexed: 11/28/2022] Open
Abstract
Among the many unsolved problems of calcium signalling, the role of calcium elevations in apoptotic and necrotic cell death has been a focus of research in recent years. Evidence has been presented that calcium oscillations can effectively trigger apoptosis under certain conditions and that dysregulation of calcium signalling is a common cause of cell death. These effects are regularly mediated through calcium signal propagation to the mitochondria and the ensuing mitochondrial membrane permeabilization and release of pro-apoptotic factors from mitochondria to the cytoplasm. The progress in this area depended on the development of (1) fluorescent/luminescent probes, including fluorescent proteins that can be genetically targeted to different intracellular locations and (2) the digital imaging technology, fluorescence-activated cell sorting and fluorescent high throughput approaches, which allowed dynamic measurements of both [Ca2+] in the intracellular compartments of interest and the downstream processes. Fluorescence single cell imaging has been the only possible approach to resolve the cell-to-cell heterogeneity and the complex subcellular spatiotemporal organization of the cytoplasmic and mitochondrial calcium signals and downstream events. We outline here fluorometric and fluorescence imaging protocols that we set up for the study of calcium in the context of apoptosis.
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Affiliation(s)
- Soumya Sinha Roy
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, 1020 Locust Street, Suite 253 JAH, Philadelphia, PA 19107, USA
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Hacker K, Medler KF. Mitochondrial calcium buffering contributes to the maintenance of Basal calcium levels in mouse taste cells. J Neurophysiol 2008; 100:2177-91. [PMID: 18684902 DOI: 10.1152/jn.90534.2008] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Taste stimuli are detected by taste receptor cells present in the oral cavity using diverse signaling pathways. Some taste stimuli are detected by G protein-coupled receptors (GPCRs) that cause calcium release from intracellular stores, whereas other stimuli depolarize taste cells to cause calcium influx through voltage-gated calcium channels (VGCCs). Although taste cells use two distinct mechanisms to transmit taste signals, increases in cytosolic calcium are critical for normal responses in both pathways. This creates a need to tightly control intracellular calcium levels in all transducing taste cells. To date, however, the mechanisms used by taste cells to regulate cytosolic calcium levels have not been identified. Studies in other cell types have shown that mitochondria can be important calcium buffers, even during small changes in calcium loads. In this study, we used calcium imaging to characterize the role of mitochondria in buffering calcium levels in taste cells. We discovered that mitochondria make important contributions to the maintenance of resting calcium levels in taste cells by routinely buffering a constitutive calcium influx across the plasma membrane. This is unusual because in other cell types, mitochondrial calcium buffering primarily affects large evoked calcium responses. We also found that the amount of calcium that is buffered by mitochondria varies with the signaling pathways used by the taste cells. A transient receptor potential (TRP) channel, likely TRPV1 or a taste variant of TRPV1, contributes to the constitutive calcium influx.
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Affiliation(s)
- Kyle Hacker
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
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Vetter I, Cheng W, Peiris M, Wyse BD, Roberts-Thomson SJ, Zheng J, Monteith GR, Cabot PJ. Rapid, opioid-sensitive mechanisms involved in transient receptor potential vanilloid 1 sensitization. J Biol Chem 2008; 283:19540-50. [PMID: 18482991 DOI: 10.1074/jbc.m707865200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
TRPV1 is a nociceptive, Ca2+-selective ion channel involved in the development of several painful conditions. Sensitization of TRPV1 responses by cAMP-dependent PKA crucially contributes to the development of inflammatory hyperalgesia. However, the pathways involved in potentiation of TRPV1 responses by cAMP-dependent PKA remain largely unknown. Using HEK cells stably expressing TRPV1 and the mu opioid receptor, we demonstrated that treatment with the adenylate cyclase activator forskolin significantly increased the multimeric TRPV1 species. Pretreatment with the mu opioid receptor agonist morphine reversed this increased TRPV1 multimerization. FRET analysis revealed that treatment with forskolin did not cause multimerization of pre-existing TRPV1 monomers on the plasma membrane and that intracellular pools of TRPV1 exist mostly as monomers in this model. This suggests that increased TRPV1 multimerization occurred from an intracellular store of inactive TRPV1 monomers. Treatment with forskolin also caused an increase in TRPV1 expression on the plasma membrane not resulting from increased TRPV1 expression, and this rapid TRPV1 translocation was inhibited by treatment with morphine. Thus, potentiation of TRPV1 responses by cAMP-dependent PKA involves plasma membrane insertion of functional TRPV1 multimers formed from an intracellular store of inactive TRPV1 monomers. This potentiation occurs rapidly and can be dynamically modulated by activation of the mu opioid receptor under conditions where cAMP levels are raised, such as with inflammation. Increased translocation and multimerization of TRPV1 channels provide a cellular mechanism for fine-tuning of nociceptive responses that allow for rapid modulation of TRPV1 responses independent of transcriptional changes.
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Affiliation(s)
- Irina Vetter
- School of Pharmacy, The University of Queensland, St Lucia, Queensland 4072, Australia
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Zhang H, Das S, Li QZ, Dragatsis I, Repa J, Zeitlin S, Hajnóczky G, Bezprozvanny I. Elucidating a normal function of huntingtin by functional and microarray analysis of huntingtin-null mouse embryonic fibroblasts. BMC Neurosci 2008; 9:38. [PMID: 18412970 PMCID: PMC2377268 DOI: 10.1186/1471-2202-9-38] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Accepted: 04/15/2008] [Indexed: 11/10/2022] Open
Abstract
Background The polyglutamine expansion in huntingtin (Htt) protein is a cause of Huntington's disease (HD). Htt is an essential gene as deletion of the mouse Htt gene homolog (Hdh) is embryonic lethal in mice. Therefore, in addition to elucidating the mechanisms responsible for polyQ-mediated pathology, it is also important to understand the normal function of Htt protein for both basic biology and for HD. Results To systematically search for a mouse Htt function, we took advantage of the Hdh +/- and Hdh-floxed mice and generated four mouse embryonic fibroblast (MEF) cells lines which contain a single copy of the Hdh gene (Hdh-HET) and four MEF lines in which the Hdh gene was deleted (Hdh-KO). The function of Htt in calcium (Ca2+) signaling was analyzed in Ca2+ imaging experiments with generated cell lines. We found that the cytoplasmic Ca2+ spikes resulting from the activation of inositol 1,4,5-trisphosphate receptor (InsP3R) and the ensuing mitochondrial Ca2+ signals were suppressed in the Hdh-KO cells when compared to Hdh-HET cells. Furthermore, in experiments with permeabilized cells we found that the InsP3-sensitivity of Ca2+ mobilization from endoplasmic reticulum was reduced in Hdh-KO cells. These results indicated that Htt plays an important role in modulating InsP3R-mediated Ca2+ signaling. To further evaluate function of Htt, we performed genome-wide transcription profiling of generated Hdh-HET and Hdh-KO cells by microarray. Our results revealed that 106 unique transcripts were downregulated by more than two-fold with p < 0.05 and 173 unique transcripts were upregulated at least two-fold with p < 0.05 in Hdh-KO cells when compared to Hdh-HET cells. The microarray results were confirmed by quantitative real-time PCR for a number of affected transcripts. Several signaling pathways affected by Hdh gene deletion were identified from annotation of the microarray results. Conclusion Functional analysis of generated Htt-null MEF cells revealed that Htt plays a direct role in Ca2+ signaling by modulating InsP3R sensitivity to InsP3. The genome-wide transcriptional profiling of Htt-null cells yielded novel and unique information about the normal function of Htt in cells, which may contribute to our understanding and treatment of HD.
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Affiliation(s)
- Hua Zhang
- Department of Physiology, UT Southwestern Medical Center at Dallas, Dallas, TX 75390, USA.
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Joseph SK, Hajnóczky G. IP3 receptors in cell survival and apoptosis: Ca2+ release and beyond. Apoptosis 2008; 12:951-68. [PMID: 17294082 DOI: 10.1007/s10495-007-0719-7] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Inositol 1,4,5-trisphosphate receptors (IP(3)Rs) serve to discharge Ca(2+) from ER stores in response to agonist stimulation. The present review summarizes the role of these receptors in models of Ca(2+)-dependent apoptosis. In particular we focus on the regulation of IP(3)Rs by caspase-3 cleavage, cytochrome c, anti-apoptotic proteins and Akt kinase. We also address the evidence that some of the effects of IP(3)Rs in apoptosis may be independent of their ion-channel function. The role of IP(3)Rs in delivering Ca(2+) to the mitochondria is discussed from the perspective of the factors determining inter-organellar dynamics and the spatial proximity of mitochondria and ER membranes.
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Affiliation(s)
- Suresh K Joseph
- Department of Pathology & Cell Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA.
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Beta-amyloid enhances intracellular calcium rises mediated by repeated activation of intracellular calcium stores and nicotinic receptors in acutely dissociated rat basal forebrain neurons. ACTA ACUST UNITED AC 2007; 35:173-86. [PMID: 17957482 DOI: 10.1007/s11068-007-9010-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2006] [Revised: 03/07/2007] [Accepted: 03/14/2007] [Indexed: 10/22/2022]
Abstract
Beta-amyloid, a 39-43 amino acid peptide, may exert its biological effects via neuronal nicotinic acetylcholine receptors. Using the ratiometric dye, fura-2, we examined the effect of soluble beta-amyloid(1-42) on the concentration of intracellular Ca(2+) ([Ca(2+)](i)) in acutely dissociated rat basal forebrain neurons. Focal applications of nicotine (0.5-20 mM), evoked dose-dependent increases in intracellular [Ca(2+)](i) that were mediated by the entry of extracellular Ca(2+) via nicotinic acetylcholine receptors, and the release of intracellular Ca(2+) from stores. With repeated nicotine challenges, the nicotinic responses were potentiated by 98 +/- 12% (P < 0.05) while beta-amyloid(1-42)(100 nM) was present for approximately 5 min. This potentiation became larger during the subsequent washout of beta-amyloid(1-42), which was associated with a gradual rise in baseline [Ca(2+)](i). Application of beta-amyloid(1-42)by itself did not alter [Ca(2+)](i), and beta-amyloid(1-42)also had no significant effect on the response to repeated KCl challenges. Therefore, beta-amyloid(1-42) caused neither gross disturbance of cellular Ca(2+) homeostasis nor enhancement of voltage-gated Ca(2+) channels. Interestingly, beta-amyloid(1-42) transiently potentiated the response to repeated caffeine challenges, which was also associated with a transient rise in baseline [Ca(2+)](i). beta-amyloid(1-42) potentiation of nicotine-evoked rises in [Ca(2+)](i) was reversed by the SERCA pump inhibitor, thapsigargin, and the mitochondrial Na(+)/Ca(2+) exchanger inhibitor, CGP-37157. These results suggest that the dysregulation of [Ca(2+)](i) by beta-amyloid(1-42) during multiple challenges with nicotine or caffeine involved the sensitization or overfilling of intracellular stores that are maintained by SERCA pump and Ca(2+) efflux from the mitochondria.
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Kopach O, Kruglikov I, Pivneva T, Voitenko N, Fedirko N. Functional coupling between ryanodine receptors, mitochondria and Ca(2+) ATPases in rat submandibular acinar cells. Cell Calcium 2007; 43:469-81. [PMID: 17889347 DOI: 10.1016/j.ceca.2007.08.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2007] [Revised: 08/01/2007] [Accepted: 08/06/2007] [Indexed: 11/17/2022]
Abstract
Agonist stimulation of exocrine cells leads to the generation of intracellular Ca(2+) signals driven by inositol 1,4,5-trisphosphate receptors (IP(3)Rs) that rapidly become global due to propagation throughout the cell. In many types of excitable cells the intracellular Ca(2+) signal is propagated by a mechanism of Ca(2+)-induced Ca(2+) release (CICR), mediated by ryanodine receptors (RyRs). Expression of RyRs in salivary gland cells has been demonstrated immunocytochemically although their functional role is not clear. We used microfluorimetry to measure Ca(2+) signals in the cytoplasm, in the endoplasmic reticulum (ER) and in mitochondria. In permeabilized acinar cells caffeine induced a dose-dependent, transient decrease of Ca(2+) concentration in the endoplasmic reticulum ([Ca(2+)](ER)). This decrease was inhibited by ryanodine but was insensitive to heparin. Application of caffeine, however, did not elevate cytosolic Ca(2+) concentration ([Ca(2+)](i)) suggesting fast local buffering of Ca(2+) released through RyRs. Indeed, activation of RyRs produced a robust mitochondrial Ca(2+) transient that was prevented by addition of Ca(2+) chelator BAPTA but not EGTA. When mitochondrial Ca(2+) uptake was blocked, activation of RyRs evoked only a non-transient increase in [Ca(2+)](i) and substantially smaller Ca(2+) release from the ER. Upon simultaneous inhibition of mitochondrial Ca(2+) uptake and either plasmalemmal or ER Ca(2+) ATPase, activation of RyRs caused a transient rise in [Ca(2+)](i). Collectively, our data suggest that Ca(2+) released through RyRs is mostly "tunnelled" to mitochondria, while Ca(2+) ATPases are responsible for the fast initial sequestration of Ca(2+). Ca(2+) uptake by mitochondria is critical for maintaining continuous CICR. A complex interplay between RyRs, mitochondria and Ca(2+) ATPases is accomplished through strategic positioning of mitochondria close to both Ca(2+) release sites in the ER and Ca(2+) pumping sites of the plasmalemma and the ER.
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Affiliation(s)
- Olga Kopach
- Department of General Physiology of Nervous System, Bogomoletz Institute of Physiology, Kiev , Ukraine
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