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Bulthuis EP, Adjobo-Hermans MJW, de Potter B, Hoogstraten S, Wezendonk LHT, Tutakhel OAZ, Wintjes LT, van den Heuvel B, Willems PHGM, Kamsteeg EJ, Gozalbo MER, Sallevelt SCEH, Koudijs SM, Nicolai J, de Bie CI, Hoogendijk JE, Koopman WJH, Rodenburg RJ. SMDT1 variants impair EMRE-mediated mitochondrial calcium uptake in patients with muscle involvement. Biochim Biophys Acta Mol Basis Dis 2023; 1869:166808. [PMID: 37454773 DOI: 10.1016/j.bbadis.2023.166808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 06/26/2023] [Accepted: 07/10/2023] [Indexed: 07/18/2023]
Abstract
Ionic calcium (Ca2+) is a key messenger in signal transduction and its mitochondrial uptake plays an important role in cell physiology. This uptake is mediated by the mitochondrial Ca2+ uniporter (MCU), which is regulated by EMRE (essential MCU regulator) encoded by the SMDT1 (single-pass membrane protein with aspartate rich tail 1) gene. This work presents the genetic, clinical and cellular characterization of two patients harbouring SMDT1 variants and presenting with muscle problems. Analysis of patient fibroblasts and complementation experiments demonstrated that these variants lead to absence of EMRE protein, induce MCU subcomplex formation and impair mitochondrial Ca2+ uptake. However, the activity of oxidative phosphorylation enzymes, mitochondrial morphology and membrane potential, as well as routine/ATP-linked respiration were not affected. We hypothesize that the muscle-related symptoms in the SMDT1 patients result from aberrant mitochondrial Ca2+ uptake.
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Affiliation(s)
- Elianne P Bulthuis
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Merel J W Adjobo-Hermans
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Bastiaan de Potter
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Saskia Hoogstraten
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands; Human and Animal Physiology, Wageningen University & Research, 6700 AH Wageningen, the Netherlands
| | - Lisanne H T Wezendonk
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Omar A Z Tutakhel
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Liesbeth T Wintjes
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Bert van den Heuvel
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Peter H G M Willems
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Centre, 6525 GA Nijmegen, the Netherlands
| | - M Estela Rubio Gozalbo
- Department of Pediatrics, Maastricht University Medical Centre, 6229 HX Maastricht, the Netherlands; Department of Clinical Genetics, Maastricht University Medical Centre, 6229 HX Maastricht, the Netherlands
| | - Suzanne C E H Sallevelt
- Department of Clinical Genetics, Maastricht University Medical Centre, 6229 HX Maastricht, the Netherlands
| | - Suzanne M Koudijs
- Department of Neurology, Maastricht University Medical Centre, 6229 HX Maastricht, the Netherlands
| | - Joost Nicolai
- Department of Neurology, Maastricht University Medical Centre, 6229 HX Maastricht, the Netherlands
| | - Charlotte I de Bie
- Department of Genetics, University Medical Centre Utrecht, 3508 AB Utrecht, the Netherlands
| | - Jessica E Hoogendijk
- Rudolf Magnus Institute of Neuroscience, University Medical Centre Utrecht, 3584 CG Utrecht, the Netherlands
| | - Werner J H Koopman
- Human and Animal Physiology, Wageningen University & Research, 6700 AH Wageningen, the Netherlands; Department of Pediatrics, Amalia Children's Hospital, Radboud Center for Mitochondrial Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands.
| | - Richard J Rodenburg
- Department of Pediatrics, Amalia Children's Hospital, Radboud Center for Mitochondrial Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands.
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2
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Suárez-Rivero JM, Pastor-Maldonado CJ, Povea-Cabello S, Álvarez-Córdoba M, Villalón-García I, Talaverón-Rey M, Suárez-Carrillo A, Munuera-Cabeza M, Reche-López D, Cilleros-Holgado P, Piñero-Perez R, Sánchez-Alcázar JA. UPR mt activation improves pathological alterations in cellular models of mitochondrial diseases. Orphanet J Rare Dis 2022; 17:204. [PMID: 35581596 PMCID: PMC9115953 DOI: 10.1186/s13023-022-02331-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 04/26/2022] [Indexed: 12/23/2022] Open
Abstract
Background Mitochondrial diseases represent one of the most common groups of genetic diseases. With a prevalence greater than 1 in 5000 adults, such diseases still lack effective treatment. Current therapies are purely palliative and, in most cases, insufficient. Novel approaches to compensate and, if possible, revert mitochondrial dysfunction must be developed. Results In this study, we tackled the issue using as a model fibroblasts from a patient bearing a mutation in the GFM1 gene, which is involved in mitochondrial protein synthesis. Mutant GFM1 fibroblasts could not survive in galactose restrictive medium for more than 3 days, making them the perfect screening platform to test several compounds. Tetracycline enabled mutant GFM1 fibroblasts survival under nutritional stress. Here we demonstrate that tetracycline upregulates the mitochondrial Unfolded Protein Response (UPRmt), a compensatory pathway regulating mitochondrial proteostasis. We additionally report that activation of UPRmt improves mutant GFM1 cellular bioenergetics and partially restores mitochondrial protein expression. Conclusions Overall, we provide compelling evidence to propose the activation of intrinsic cellular compensatory mechanisms as promising therapeutic strategy for mitochondrial diseases. Supplementary Information The online version contains supplementary material available at 10.1186/s13023-022-02331-8.
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Affiliation(s)
- Juan M Suárez-Rivero
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Carmen J Pastor-Maldonado
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Suleva Povea-Cabello
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Mónica Álvarez-Córdoba
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Irene Villalón-García
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Marta Talaverón-Rey
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Alejandra Suárez-Carrillo
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Manuel Munuera-Cabeza
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Diana Reche-López
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Paula Cilleros-Holgado
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Rocío Piñero-Perez
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - José A Sánchez-Alcázar
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain. .,Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, 41013, Seville, Spain.
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3
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Huang DX, Yu X, Yu WJ, Zhang XM, Liu C, Liu HP, Sun Y, Jiang ZP. Calcium Signaling Regulated by Cellular Membrane Systems and Calcium Homeostasis Perturbed in Alzheimer’s Disease. Front Cell Dev Biol 2022; 10:834962. [PMID: 35281104 PMCID: PMC8913592 DOI: 10.3389/fcell.2022.834962] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/31/2022] [Indexed: 12/12/2022] Open
Abstract
Although anything that changes spatiotemporally could be a signal, cells, particularly neurons, precisely manipulate calcium ion (Ca2+) to transmit information. Ca2+ homeostasis is indispensable for neuronal functions and survival. The cytosolic Ca2+ concentration ([Ca2+]CYT) is regulated by channels, pumps, and exchangers on cellular membrane systems. Under physiological conditions, both endoplasmic reticulum (ER) and mitochondria function as intracellular Ca2+ buffers. Furthermore, efficient and effective Ca2+ flux is observed at the ER-mitochondria membrane contact site (ERMCS), an intracellular membrane juxtaposition, where Ca2+ is released from the ER followed by mitochondrial Ca2+ uptake in sequence. Hence, the ER intraluminal Ca2+ concentration ([Ca2+]ER), the mitochondrial matrix Ca2+ concentration ([Ca2+]MT), and the [Ca2+]CYT are related to each other. Ca2+ signaling dysregulation and Ca2+ dyshomeostasis are associated with Alzheimer’s disease (AD), an irreversible neurodegenerative disease. The present review summarizes the cellular and molecular mechanism underlying Ca2+ signaling regulation and Ca2+ homeostasis maintenance at ER and mitochondria levels, focusing on AD. Integrating the amyloid hypothesis and the calcium hypothesis of AD may further our understanding of pathogenesis in neurodegeneration, provide therapeutic targets for chronic neurodegenerative disease in the central nervous system.
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Affiliation(s)
- Dong-Xu Huang
- Department of Hand and Foot Surgery, The First Hospital of Jilin University, Changchun, China
| | - Xin Yu
- Department of Hand and Foot Surgery, The First Hospital of Jilin University, Changchun, China
| | - Wen-Jun Yu
- Department of Hand and Foot Surgery, The First Hospital of Jilin University, Changchun, China
| | - Xin-Min Zhang
- Department of Anesthesiology, The First Hospital of Jilin University, Changchun, China
| | - Chang Liu
- Department of Neurology, The First Hospital of Jilin University, Changchun, China
| | - Hong-Ping Liu
- Department of Neurology, The First Hospital of Jilin University, Changchun, China
| | - Yue Sun
- Deparment of The First Operating Room, The First Hospital of Jilin University, Changchun, China
| | - Zi-Ping Jiang
- Department of Hand and Foot Surgery, The First Hospital of Jilin University, Changchun, China
- *Correspondence: Zi-Ping Jiang,
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4
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Neuroprotective Potential of Mild Uncoupling in Mitochondria. Pros and Cons. Brain Sci 2021; 11:brainsci11081050. [PMID: 34439669 PMCID: PMC8392724 DOI: 10.3390/brainsci11081050] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/03/2021] [Accepted: 08/05/2021] [Indexed: 02/07/2023] Open
Abstract
There has been an explosion of interest in the use of uncouplers of oxidative phosphorylation in mitochondria in the treatment of several pathologies, including neurological ones. In this review, we analyzed all the mechanisms associated with mitochondrial uncoupling and the metabolic and signaling cascades triggered by uncouplers. We provide a full set of positive and negative effects that should be taken into account when using uncouplers in experiments and clinical practice.
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5
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Chatterjee R, Paluh JL, Chowdhury S, Mondal S, Raha A, Mukherjee A. SyNC, a Computationally Extensive and Realistic Neural Net to Identify Relative Impacts of Synaptopathy Mechanisms on Glutamatergic Neurons and Their Networks in Autism and Complex Neurological Disorders. Front Cell Neurosci 2021; 15:674030. [PMID: 34354570 PMCID: PMC8330424 DOI: 10.3389/fncel.2021.674030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 05/25/2021] [Indexed: 11/24/2022] Open
Abstract
Synaptic function and experience-dependent plasticity across multiple synapses are dependent on the types of neurons interacting as well as the intricate mechanisms that operate at the molecular level of the synapse. To understand the complexity of information processing at synaptic networks will rely in part on effective computational models. Such models should also evaluate disruptions to synaptic function by multiple mechanisms. By co-development of algorithms alongside hardware, real time analysis metrics can be co-prioritized along with biological complexity. The hippocampus is implicated in autism spectrum disorders (ASD) and within this region glutamatergic neurons constitute 90% of the neurons integral to the functioning of neuronal networks. Here we generate a computational model referred to as ASD interrogator (ASDint) and corresponding hardware to enable in silicon analysis of multiple ASD mechanisms affecting glutamatergic neuron synapses. The hardware architecture Synaptic Neuronal Circuit, SyNC, is a novel GPU accelerator or neural net, that extends discovery by acting as a biologically relevant realistic neuron synapse in real time. Co-developed ASDint and SyNC expand spiking neural network models of plasticity to comparative analysis of retrograde messengers. The SyNC model is realized in an ASIC architecture, which enables the ability to compute increasingly complex scenarios without sacrificing area efficiency of the model. Here we apply the ASDint model to analyse neuronal circuitry dysfunctions associated with autism spectral disorder (ASD) synaptopathies and their effects on the synaptic learning parameter and demonstrate SyNC on an ideal ASDint scenario. Our work highlights the value of secondary pathways in regard to evaluating complex ASD synaptopathy mechanisms. By comparing the degree of variation in the synaptic learning parameter to the response obtained from simulations of the ideal scenario we determine the potency and time of the effect of a particular evaluated mechanism. Hence simulations of such scenarios in even a small neuronal network now allows us to identify relative impacts of changed parameters and their effect on synaptic function. Based on this, we can estimate the minimum fraction of a neuron exhibiting a particular dysfunction scenario required to lead to complete failure of a neural network to coordinate pre-synaptic and post-synaptic outputs.
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Affiliation(s)
- Rounak Chatterjee
- Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata, India
| | - Janet L Paluh
- SUNY Polytechnic Institute, College of Nanoscale Science and Engineering, Nanobioscience, Albany, NY, United States
| | - Souradeep Chowdhury
- Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata, India
| | - Soham Mondal
- Flash Controller Team, Memory Solutions, Samsung Semiconductor India Research, Samsung Electronics Co., Ltd., Bangalore, India
| | - Arnab Raha
- Advanced Architecture Research, Intel Intelligent Systems Group, Intel Edge AI, Intel Corporation, Santa Clara, CA, United States
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6
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Protasi F, Pietrangelo L, Boncompagni S. Improper Remodeling of Organelles Deputed to Ca 2+ Handling and Aerobic ATP Production Underlies Muscle Dysfunction in Ageing. Int J Mol Sci 2021; 22:6195. [PMID: 34201319 PMCID: PMC8228829 DOI: 10.3390/ijms22126195] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 12/28/2022] Open
Abstract
Proper skeletal muscle function is controlled by intracellular Ca2+ concentration and by efficient production of energy (ATP), which, in turn, depend on: (a) the release and re-uptake of Ca2+ from sarcoplasmic-reticulum (SR) during excitation-contraction (EC) coupling, which controls the contraction and relaxation of sarcomeres; (b) the uptake of Ca2+ into the mitochondrial matrix, which stimulates aerobic ATP production; and finally (c) the entry of Ca2+ from the extracellular space via store-operated Ca2+ entry (SOCE), a mechanism that is important to limit/delay muscle fatigue. Abnormalities in Ca2+ handling underlie many physio-pathological conditions, including dysfunction in ageing. The specific focus of this review is to discuss the importance of the proper architecture of organelles and membrane systems involved in the mechanisms introduced above for the correct skeletal muscle function. We reviewed the existing literature about EC coupling, mitochondrial Ca2+ uptake, SOCE and about the structural membranes and organelles deputed to those functions and finally, we summarized the data collected in different, but complementary, projects studying changes caused by denervation and ageing to the structure and positioning of those organelles: a. denervation of muscle fibers-an event that contributes, to some degree, to muscle loss in ageing (known as sarcopenia)-causes misplacement and damage: (i) of membrane structures involved in EC coupling (calcium release units, CRUs) and (ii) of the mitochondrial network; b. sedentary ageing causes partial disarray/damage of CRUs and of calcium entry units (CEUs, structures involved in SOCE) and loss/misplacement of mitochondria; c. functional electrical stimulation (FES) and regular exercise promote the rescue/maintenance of the proper architecture of CRUs, CEUs, and of mitochondria in both denervation and ageing. All these structural changes were accompanied by related functional changes, i.e., loss/decay in function caused by denervation and ageing, and improved function following FES or exercise. These data suggest that the integrity and proper disposition of intracellular organelles deputed to Ca2+ handling and aerobic generation of ATP is challenged by inactivity (or reduced activity); modifications in the architecture of these intracellular membrane systems may contribute to muscle dysfunction in ageing and sarcopenia.
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Affiliation(s)
- Feliciano Protasi
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy; (L.P.); (S.B.)
- DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
| | - Laura Pietrangelo
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy; (L.P.); (S.B.)
- DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
| | - Simona Boncompagni
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy; (L.P.); (S.B.)
- DNICS, Department of Neuroscience and Clinical Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
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7
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Kedra J, Lin S, Pacheco A, Gallo G, Smith GM. Axotomy Induces Drp1-Dependent Fragmentation of Axonal Mitochondria. Front Mol Neurosci 2021; 14:668670. [PMID: 34149354 PMCID: PMC8209475 DOI: 10.3389/fnmol.2021.668670] [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: 02/16/2021] [Accepted: 05/07/2021] [Indexed: 02/02/2023] Open
Abstract
It is well established that CNS axons fail to regenerate, undergo retrograde dieback, and form dystrophic growth cones due to both intrinsic and extrinsic factors. We sought to investigate the role of axonal mitochondria in the axonal response to injury. A viral vector (AAV) containing a mitochondrially targeted fluorescent protein (mitoDsRed) as well as fluorescently tagged LC3 (GFP-LC3), an autophagosomal marker, was injected into the primary motor cortex, to label the corticospinal tract (CST), of adult rats. The axons of the CST were then injured by dorsal column lesion at C4-C5. We found that mitochondria in injured CST axons near the injury site are fragmented and fragmentation of mitochondria persists for 2 weeks before returning to pre-injury lengths. Fragmented mitochondria have consistently been shown to be dysfunctional and detrimental to cellular health. Inhibition of Drp1, the GTPase responsible for mitochondrial fission, using a specific pharmacological inhibitor (mDivi-1) blocked fragmentation. Additionally, it was determined that there is increased mitophagy in CST axons following Spinal cord injury (SCI) based on increased colocalization of mitochondria and LC3. In vitro models revealed that mitochondrial divalent ion uptake is necessary for injury-induced mitochondrial fission, as inhibiting the mitochondrial calcium uniporter (MCU) using RU360 prevented injury-induced fission. This phenomenon was also observed in vivo. These studies indicate that following the injury, both in vivo and in vitro, axonal mitochondria undergo increased fission, which may contribute to the lack of regeneration seen in CNS neurons.
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Affiliation(s)
- Joseph Kedra
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Shen Lin
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Almudena Pacheco
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Gianluca Gallo
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States.,Department of Anatomy and Cell Biology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - George M Smith
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States.,Department of Neuroscience, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
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Wang C, Baradaran R, Long SB. Structure and Reconstitution of an MCU-EMRE Mitochondrial Ca 2+ Uniporter Complex. J Mol Biol 2020; 432:5632-5648. [PMID: 32841658 PMCID: PMC7577567 DOI: 10.1016/j.jmb.2020.08.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/15/2020] [Accepted: 08/18/2020] [Indexed: 10/23/2022]
Abstract
The proteins MCU and EMRE form the minimal functional unit of the mitochondrial calcium uniporter complex in metazoans, a highly selective and tightly controlled Ca2+ channel of the inner mitochondrial membrane that regulates cellular metabolism. Here we present functional reconstitution of an MCU-EMRE complex from the red flour beetle, Tribolium castaneum, and a cryo-EM structure of the complex at 3.5 Å resolution. Using a novel assay, we demonstrate robust Ca2+ uptake into proteoliposomes containing the purified complex. Uptake is dependent on EMRE and also on the mitochondrial lipid cardiolipin. The structure reveals a tetrameric channel with a single ion pore. EMRE is located at the periphery of the transmembrane domain and associates primarily with the first transmembrane helix of MCU. Coiled-coil and juxtamembrane domains within the matrix portion of the complex adopt markedly different conformations than in a structure of a human MCU-EMRE complex, suggesting that the structures represent different conformations of these functionally similar metazoan channels.
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Affiliation(s)
- Chongyuan Wang
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Rozbeh Baradaran
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Stephen Barstow Long
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
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9
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Sugano E, Endo Y, Sugai A, Kikuchi Y, Tabata K, Ozaki T, Kurose T, Takai Y, Mitsuguchi Y, Honma Y, Tomita H. Geranylgeranyl acetone prevents glutamate-induced cell death in HT-22 cells by increasing mitochondrial membrane potential. Eur J Pharmacol 2020; 883:173193. [PMID: 32659301 DOI: 10.1016/j.ejphar.2020.173193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 05/07/2020] [Accepted: 05/11/2020] [Indexed: 12/19/2022]
Abstract
Geranylgeranyl acetone (GGA) protects against various types of cell damages by upregulating heat shock proteins. We investigated whether GGA protects neuronal cells from cell death induced by oxidative stress. Glutamate exposure was lethal to HT-22 cells which comprise a neuronal line derived from mouse hippocampus. This configuration is often used as a model for hippocampus neurodegeneration in vitro. In the present study, GGA protected HT-22 cells from glutamate-induced oxidative stress. GGA pretreatment did not induce heat shock proteins (Hsps). Moreover, reactive oxygen species increased to the same extent in both GGA-pretreated and untreated cells exposed to glutamate. In contrast, glutamate exposure and GGA pretreatment increased mitochondrial membrane potential. However, increases in intracellular Ca2+ concentration were inhibited by GGA pretreatment. In addition, the increase of phosphorylated ERKs by the glutamate exposure was inhibited by GGA pretreatment. These findings suggest that GGA protects HT-22 cells from glutamate-provoked cell death without Hsp induction and that the mitochondrial calcium buffering capacity plays an important role in this protective effect.
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Affiliation(s)
- Eriko Sugano
- Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University Division of Science and Engineering, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan.
| | - Yuka Endo
- Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University Division of Science and Engineering, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan.
| | - Akihisa Sugai
- Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University Division of Science and Engineering, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan.
| | - Yuki Kikuchi
- Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University Division of Science and Engineering, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan.
| | - Kitako Tabata
- Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University Division of Science and Engineering, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan.
| | - Taku Ozaki
- Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University Division of Science and Engineering, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan.
| | - Takahiro Kurose
- Rohto Pharmaceutical Co., Ltd, 6-5-4 Kunimidai, Kizugawa, Kyoto, 619-0216, Japan.
| | - Yoshihiro Takai
- Rohto Pharmaceutical Co., Ltd, 6-5-4 Kunimidai, Kizugawa, Kyoto, 619-0216, Japan.
| | - Yoko Mitsuguchi
- Rohto Pharmaceutical Co., Ltd, 6-5-4 Kunimidai, Kizugawa, Kyoto, 619-0216, Japan.
| | - Yoichi Honma
- Rohto Pharmaceutical Co., Ltd, 6-5-4 Kunimidai, Kizugawa, Kyoto, 619-0216, Japan.
| | - Hiroshi Tomita
- Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University Division of Science and Engineering, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan; Clinical Research, Innovation and Education Center, Tohoku University Hospital, 1-1 Seiryo, Aoba, Sendai, Miyagi, 980-8574, Japan.
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10
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Shah SI, Ullah G. The Function of Mitochondrial Calcium Uniporter at the Whole-Cell and Single Mitochondrion Levels in WT, MICU1 KO, and MICU2 KO Cells. Cells 2020; 9:E1520. [PMID: 32580385 PMCID: PMC7349584 DOI: 10.3390/cells9061520] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/15/2020] [Accepted: 06/16/2020] [Indexed: 01/05/2023] Open
Abstract
Mitochondrial Ca2+ ([Ca2+]M) uptake through its Ca2+ uniporter (MCU) is central to many cell functions such as bioenergetics, spatiotemporal organization of Ca2+ signals, and apoptosis. MCU activity is regulated by several intrinsic proteins including MICU1, MICU2, and EMRE. While significant details about the role of MICU1, MICU2, and EMRE in MCU function have emerged recently, a key challenge for the future experiments is to investigate how these regulatory proteins modulate mitochondrial Ca2+ influx through MCU in intact cells under pathophysiological conditions. This is further complicated by the fact that several variables affecting MCU function change dynamically as cell functions. To overcome this void, we develop a data-driven model that closely replicates the behavior of MCU under a wide range of cytosolic Ca2+ ([Ca2+]C), [Ca2+]M, and mitochondrial membrane potential values in WT, MICU1 knockout (KO), and MICU2 KO cells at the single mitochondrion and whole-cell levels. The model is extended to investigate how MICU1 or MICU2 KO affect mitochondrial function. Moreover, we show how Ca2+ buffering proteins, the separation between mitochondrion and Ca2+-releasing stores, and the duration of opening of Ca2+-releasing channels affect mitochondrial function under different conditions. Finally, we demonstrate an easy extension of the model to single channel function of MCU.
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Affiliation(s)
| | - Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, FL 33647, USA;
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11
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Sterea AM, El Hiani Y. The Role of Mitochondrial Calcium Signaling in the Pathophysiology of Cancer Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:747-770. [PMID: 31646533 DOI: 10.1007/978-3-030-12457-1_30] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The pioneering work of Richard Altman on the presence of mitochondria in cells set in motion a field of research dedicated to uncovering the secrets of the mitochondria. Despite limitations in studying the structure and function of the mitochondria, advances in our understanding of this organelle prompted the development of potential treatments for various diseases, from neurodegenerative conditions to muscular dystrophy and cancer. As the powerhouses of the cell, the mitochondria represent the essence of cellular life and as such, a selective advantage for cancer cells. Much of the function of the mitochondria relies on Ca2+ homeostasis and the presence of effective Ca2+ signaling to maintain the balance between mitochondrial function and dysfunction and subsequently, cell survival. Ca2+ regulates the mitochondrial respiration rate which in turn increases ATP synthesis, but too much Ca2+ can also trigger the mitochondrial apoptosis pathway; however, cancer cells have evolved mechanisms to modulate mitochondrial Ca2+ influx and efflux in order to sustain their metabolic demand and ensure their survival. Therefore, targeting the mitochondrial Ca2+ signaling involved in the bioenergetic and apoptotic pathways could serve as potential approaches to treat cancer patients. This chapter will review the role of Ca2+ signaling in mediating the function of the mitochondria and its involvement in health and disease with special focus on the pathophysiology of cancer.
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Affiliation(s)
- Andra M Sterea
- Departments of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Yassine El Hiani
- Departments of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada.
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12
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MICU1 and MICU2 Play an Essential Role in Mitochondrial Ca 2+ Uptake, Growth, and Infectivity of the Human Pathogen Trypanosoma cruzi. mBio 2019; 10:mBio.00348-19. [PMID: 31064825 PMCID: PMC6509184 DOI: 10.1128/mbio.00348-19] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The mitochondrial Ca2+ uptake in trypanosomatids, which belong to the eukaryotic supergroup Excavata, shares biochemical characteristics with that of animals, which, together with fungi, belong to the supergroup Opisthokonta. However, the composition of the mitochondrial calcium uniporter (MCU) complex in trypanosomatids is quite peculiar, suggesting lineage-specific adaptations. In this work, we used Trypanosoma cruzi to study the role of orthologs for mitochondrial calcium uptake 1 (MICU1) and MICU2 in mitochondrial Ca2+ uptake. T. cruzi MICU1 (TcMICU1) and TcMICU2 have mitochondrial targeting signals, two canonical EF-hand calcium-binding domains, and localize to the mitochondria. Using the CRISPR/Cas9 system (i.e., clustered regularly interspaced short palindromic repeats with Cas9), we generated TcMICU1 and TcMICU2 knockout (-KO) cell lines. Ablation of either TcMICU1 or TcMICU2 showed a significantly reduced mitochondrial Ca2+ uptake in permeabilized epimastigotes without dissipation of the mitochondrial membrane potential or effects on the AMP/ATP ratio or citrate synthase activity. However, none of these proteins had a gatekeeper function at low cytosolic Ca2+ concentrations ([Ca2+]cyt), as occurs with their mammalian orthologs. TcMICU1-KO and TcMICU2-KO epimastigotes had a lower growth rate and impaired oxidative metabolism, while infective trypomastigotes have a reduced capacity to invade host cells and to replicate within them as amastigotes. The findings of this work, which is the first to study the role of MICU1 and MICU2 in organisms evolutionarily distant from animals, suggest that, although these components were probably present in the last eukaryotic common ancestor (LECA), they developed different roles during evolution of different eukaryotic supergroups. The work also provides new insights into the adaptations of trypanosomatids to their particular life styles.IMPORTANCE Trypanosoma cruzi is the etiologic agent of Chagas disease and belongs to the early-branching eukaryotic supergroup Excavata. Its mitochondrial calcium uniporter (MCU) subunit shares similarity with the animal ortholog that was important to discover its encoding gene. In animal cells, the MICU1 and MICU2 proteins act as Ca2+ sensors and gatekeepers of the MCU, preventing Ca2+ uptake under resting conditions and favoring it at high cytosolic Ca2+ concentrations ([Ca2+]cyt). Using the CRISPR/Cas9 technique, we generated TcMICU1 and TcMICU2 knockout cell lines and showed that MICU1 and -2 do not act as gatekeepers at low [Ca2+]cyt but are essential for normal growth, host cell invasion, and intracellular replication, revealing lineage-specific adaptations.
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13
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Baselet B, Sonveaux P, Baatout S, Aerts A. Pathological effects of ionizing radiation: endothelial activation and dysfunction. Cell Mol Life Sci 2019; 76:699-728. [PMID: 30377700 PMCID: PMC6514067 DOI: 10.1007/s00018-018-2956-z] [Citation(s) in RCA: 123] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 10/19/2018] [Accepted: 10/23/2018] [Indexed: 01/13/2023]
Abstract
The endothelium, a tissue that forms a single layer of cells lining various organs and cavities of the body, especially the heart and blood as well as lymphatic vessels, plays a complex role in vascular biology. It contributes to key aspects of vascular homeostasis and is also involved in pathophysiological processes, such as thrombosis, inflammation, and hypertension. Epidemiological data show that high doses of ionizing radiation lead to cardiovascular disease over time. The aim of this review is to summarize the current knowledge on endothelial cell activation and dysfunction after ionizing radiation exposure as a central feature preceding the development of cardiovascular diseases.
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Affiliation(s)
- Bjorn Baselet
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK•CEN), Mol, Belgium
- Institute of Experimental and Clinical Research (IREC), Pole of Pharmacology and Therapeutics, Université catholique de Louvain (UCL), Brussels, Belgium
| | - Pierre Sonveaux
- Institute of Experimental and Clinical Research (IREC), Pole of Pharmacology and Therapeutics, Université catholique de Louvain (UCL), Brussels, Belgium
| | - Sarah Baatout
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK•CEN), Mol, Belgium
- Department of Molecular Biotechnology, Ghent University, Ghent, Belgium
| | - An Aerts
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK•CEN), Mol, Belgium.
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14
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SR-mitochondria communication in adult cardiomyocytes: A close relationship where the Ca 2+ has a lot to say. Arch Biochem Biophys 2019; 663:259-268. [PMID: 30685253 DOI: 10.1016/j.abb.2019.01.026] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Revised: 01/14/2019] [Accepted: 01/22/2019] [Indexed: 02/07/2023]
Abstract
In adult cardiomyocytes, T-tubules, junctional sarcoplasmic reticulum (jSR), and mitochondria juxtapose each other and form a unique and highly repetitive functional structure along the cell. The close apposition between jSR and mitochondria creates high Ca2+ microdomains at the contact sites, increasing the efficiency of the excitation-contraction-bioenergetics coupling, where the Ca2+ transfer from SR to mitochondria plays a critical role. The SR-mitochondria contacts are established through protein tethers, with mitofusin 2 the most studied SR-mitochondrial "bridge", albeit controversial. Mitochondrial Ca2+ uptake is further optimized with the mitochondrial Ca2+ uniporter preferentially localized in the jSR-mitochondria contact sites and the mitochondrial Na+/Ca2+ exchanger localized away from these sites. Despite all these unique features facilitating the privileged transport of Ca2+ from SR to mitochondria in adult cardiomyocytes, the question remains whether mitochondrial Ca2+ concentrations oscillate in synchronicity with cytosolic Ca2+ transients during heartbeats. Proper Ca2+ transfer controls not only the process of mitochondrial bioenergetics, but also of mitochondria-mediated cell death, autophagy/mitophagy, mitochondrial fusion/fission dynamics, reactive oxygen species generation, and redox signaling, among others. Our review focuses specifically on Ca2+ signaling between SR and mitochondria in adult cardiomyocytes. We discuss the physiological and pathological implications of this SR-mitochondrial Ca2+ signaling, research gaps, and future trends.
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15
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Vercesi AE, Castilho RF, Kowaltowski AJ, de Oliveira HCF, de Souza-Pinto NC, Figueira TR, Busanello ENB. Mitochondrial calcium transport and the redox nature of the calcium-induced membrane permeability transition. Free Radic Biol Med 2018; 129:1-24. [PMID: 30172747 DOI: 10.1016/j.freeradbiomed.2018.08.034] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/16/2018] [Accepted: 08/28/2018] [Indexed: 12/16/2022]
Abstract
Mitochondria possess a Ca2+ transport system composed of separate Ca2+ influx and efflux pathways. Intramitochondrial Ca2+ concentrations regulate oxidative phosphorylation, required for cell function and survival, and mitochondrial redox balance, that participates in a myriad of signaling and damaging pathways. The interaction between Ca2+ accumulation and redox imbalance regulates opening and closing of a highly regulated inner membrane pore, the membrane permeability transition pore (PTP). In this review, we discuss the regulation of the PTP by mitochondrial oxidants, reactive nitrogen species, and the interactions between these species and other PTP inducers. In addition, we discuss the involvement of mitochondrial redox imbalance and PTP in metabolic conditions such as atherogenesis, diabetes, obesity and in mtDNA stability.
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Affiliation(s)
- Anibal E Vercesi
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil.
| | - Roger F Castilho
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - Alicia J Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Helena C F de Oliveira
- Departamento de Biologia Estrutural e Funcional, Instituto de Biologia, Universidade Estadual de Campinas, SP, Brazil
| | - Nadja C de Souza-Pinto
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Tiago R Figueira
- Escola de Educação Física e Esporte de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Estela N B Busanello
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil
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16
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Payne R, Hoff H, Roskowski A, Foskett JK. MICU2 Restricts Spatial Crosstalk between InsP 3R and MCU Channels by Regulating Threshold and Gain of MICU1-Mediated Inhibition and Activation of MCU. Cell Rep 2018; 21:3141-3154. [PMID: 29241542 DOI: 10.1016/j.celrep.2017.11.064] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 10/04/2017] [Accepted: 11/17/2017] [Indexed: 12/28/2022] Open
Abstract
Ca2+ entry into mitochondria is mediated by the Ca2+ uniporter-channel complex containing MCU, the Ca2+-selective pore, and associated regulatory proteins. The roles of MICU proteins are controversial. MICU1 was proposed to be necessary for MCU activity, whereas subsequent studies suggested it inhibits the channel in the low-cytoplasmic Ca2+ ([Ca2+]c) regime, a mechanism referred to as "gatekeeping," that imposes a [Ca2+]c threshold for channel activation at ∼1-3 μM. Here, we measured MCU activity over a wide range of quantitatively controlled and recorded [Ca2+]c. MICU1 alone can mediate gatekeeping as well as highly cooperative activation of MCU activity, whereas the fundamental role of MICU2 is to regulate the threshold and gain of MICU1-mediated inhibition and activation of MCU. Our results provide a unifying model for the roles of the MICU1/2 heterodimer in MCU-channel regulation and suggest an evolutionary role for MICU2 in spatially restricting Ca2+ crosstalk between single inositol 1,4,5-trisphosphate receptor (InsP3R) and MCU channels.
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Affiliation(s)
- Riley Payne
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Henry Hoff
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Anne Roskowski
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - J Kevin Foskett
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA; Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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17
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Cryo-EM structures of fungal and metazoan mitochondrial calcium uniporters. Nature 2018; 559:580-584. [PMID: 29995857 DOI: 10.1038/s41586-018-0331-8] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 06/19/2018] [Indexed: 12/22/2022]
Abstract
The mitochondrial calcium uniporter (MCU) is a highly selective calcium channel and a major route of calcium entry into mitochondria. How the channel catalyses ion permeation and achieves ion selectivity are not well understood, partly because MCU is thought to have a distinct architecture in comparison to other cellular channels. Here we report cryo-electron microscopy reconstructions of MCU channels from zebrafish and Cyphellophora europaea at 8.5 Å and 3.2 Å resolutions, respectively. In contrast to a previous report of pentameric stoichiometry for MCU, both channels are tetramers. The atomic model of C. europaea MCU shows that a conserved WDXXEP signature sequence forms the selectivity filter, in which calcium ions are arranged in single file. Coiled-coil legs connect the pore to N-terminal domains in the mitochondrial matrix. In C. europaea MCU, the N-terminal domains assemble as a dimer of dimers; in zebrafish MCU, they form an asymmetric crescent. The structures define principles that underlie ion permeation and calcium selectivity in this unusual channel.
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18
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Zorova LD, Popkov VA, Plotnikov EY, Silachev DN, Pevzner IB, Jankauskas SS, Babenko VA, Zorov SD, Balakireva AV, Juhaszova M, Sollott SJ, Zorov DB. Mitochondrial membrane potential. Anal Biochem 2018; 552:50-59. [PMID: 28711444 PMCID: PMC5792320 DOI: 10.1016/j.ab.2017.07.009] [Citation(s) in RCA: 1056] [Impact Index Per Article: 176.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/06/2017] [Accepted: 07/07/2017] [Indexed: 01/13/2023]
Abstract
The mitochondrial membrane potential (ΔΨm) generated by proton pumps (Complexes I, III and IV) is an essential component in the process of energy storage during oxidative phosphorylation. Together with the proton gradient (ΔpH), ΔΨm forms the transmembrane potential of hydrogen ions which is harnessed to make ATP. The levels of ΔΨm and ATP in the cell are kept relatively stable although there are limited fluctuations of both these factors that can occur reflecting normal physiological activity. However, sustained changes in both factors may be deleterious. A long-lasting drop or rise of ΔΨm vs normal levels may induce unwanted loss of cell viability and be a cause of various pathologies. Among other factors, ΔΨm plays a key role in mitochondrial homeostasis through selective elimination of dysfunctional mitochondria. It is also a driving force for transport of ions (other than H+) and proteins which are necessary for healthy mitochondrial functioning. We propose additional potential mechanisms for which ΔΨm is essential for maintenance of cellular health and viability and provide recommendations how to accurately measure ΔΨm in a cell and discuss potential sources of artifacts.
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Affiliation(s)
- Ljubava D Zorova
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation; International Laser Center, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Vasily A Popkov
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation; Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Egor Y Plotnikov
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Denis N Silachev
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Irina B Pevzner
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Stanislovas S Jankauskas
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Valentina A Babenko
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation; Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Savva D Zorov
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Anastasia V Balakireva
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russian Federation
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Dmitry B Zorov
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation; Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA.
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19
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Li X, Zhang S, Liu X, Wang X, Zhou A, Liu P. Dynamic analysis on the calcium oscillation model considering the influences of mitochondria. Biosystems 2017; 163:36-46. [PMID: 29229425 DOI: 10.1016/j.biosystems.2017.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 10/08/2017] [Accepted: 12/05/2017] [Indexed: 11/26/2022]
Abstract
Based on the model considering the influences of mitochondria, a further theoretical study on the dynamic behaviors of calcium signals is made. First of all, the reason for the generation and disappearance of calcium oscillations is verified in theory. Second, an analysis on the model considering the influences of mitochondria and the model neglecting the influences of mitochondria is carried out. Third, β (representing calcium leak) is introduced and it can be found that with the increase of β, the Hopf bifurcation points of system move towards the decreasing direction of μ (representing stimulus intensity) and calcium oscillations region gradually decreases. Forth, the study on τh (representing relaxation time) indicates that with the increase of τh, the second Hopf bifurcation point of system moves towards the increasing direction of μ and calcium oscillations region gradually increases. Under certain stimulus intensity, when relaxation time increases, calcium oscillation peak rises rapidly and the period increases obviously. Fifth, two-parameter bifurcation diagram of Vm1 (representing mitochondria activity) and μ contains three regions: stable region, oscillation region and unstable region. When the parameters fall in the unstable region Ca2+ gather towards mitochondria and further lead to cell apoptosis. With the increase of Vm1, calcium oscillations region shrinks gradually. Vm1 and μ both play a key role in regulating cell apoptosis. Only when Vm1 and μ are high enough can cells enter into programmed cell death and the higher Vm1 is, the lower the stimulus intensity required by cell apoptosis is.
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Affiliation(s)
- Xiang Li
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300354, PR China; Tianjin Key Laboratory of Nonlinear Dynamics and Chaos Control, Tianjin 300354, PR China.
| | - Suxia Zhang
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300354, PR China; Tianjin Key Laboratory of Nonlinear Dynamics and Chaos Control, Tianjin 300354, PR China.
| | - Xijun Liu
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300354, PR China; Tianjin Key Laboratory of Nonlinear Dynamics and Chaos Control, Tianjin 300354, PR China
| | - Xiaojing Wang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300354, PR China
| | - Anqi Zhou
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300354, PR China; Tianjin Key Laboratory of Nonlinear Dynamics and Chaos Control, Tianjin 300354, PR China
| | - Peng Liu
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300354, PR China; Tianjin Key Laboratory of Nonlinear Dynamics and Chaos Control, Tianjin 300354, PR China
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Cheung LTY, Manthey AL, Lai JSM, Chiu K. Targeted Delivery of Mitochondrial Calcium Channel Regulators: The Future of Glaucoma Treatment? Front Neurosci 2017; 11:648. [PMID: 29213227 PMCID: PMC5702640 DOI: 10.3389/fnins.2017.00648] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 11/07/2017] [Indexed: 11/18/2022] Open
Affiliation(s)
- Leanne T Y Cheung
- Department of Ophthalmology, University of Hong Kong, Hong Kong, China
| | - Abby L Manthey
- Department of Ophthalmology, University of Hong Kong, Hong Kong, China
| | - Jimmy S M Lai
- Department of Ophthalmology, University of Hong Kong, Hong Kong, China
| | - Kin Chiu
- Department of Ophthalmology, University of Hong Kong, Hong Kong, China
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21
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Systematic Identification of MCU Modulators by Orthogonal Interspecies Chemical Screening. Mol Cell 2017; 67:711-723.e7. [PMID: 28820965 DOI: 10.1016/j.molcel.2017.07.019] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 06/05/2017] [Accepted: 07/19/2017] [Indexed: 12/31/2022]
Abstract
The mitochondrial calcium uniporter complex is essential for calcium (Ca2+) uptake into mitochondria of all mammalian tissues, where it regulates bioenergetics, cell death, and Ca2+ signal transduction. Despite its involvement in several human diseases, we currently lack pharmacological agents for targeting uniporter activity. Here we introduce a high-throughput assay that selects for human MCU-specific small-molecule modulators in primary drug screens. Using isolated yeast mitochondria, reconstituted with human MCU, its essential regulator EMRE, and aequorin, and exploiting a D-lactate- and mannitol/sucrose-based bioenergetic shunt that greatly minimizes false-positive hits, we identify mitoxantrone out of more than 600 clinically approved drugs as a direct selective inhibitor of human MCU. We validate mitoxantrone in orthogonal mammalian cell-based assays, demonstrating that our screening approach is an effective and robust tool for MCU-specific drug discovery and, more generally, for the identification of compounds that target mitochondrial functions.
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22
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Kannurpatti SS. Mitochondrial calcium homeostasis: Implications for neurovascular and neurometabolic coupling. J Cereb Blood Flow Metab 2017; 37:381-395. [PMID: 27879386 PMCID: PMC5381466 DOI: 10.1177/0271678x16680637] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mitochondrial function is critical to maintain high rates of oxidative metabolism supporting energy demands of both spontaneous and evoked neuronal activity in the brain. Mitochondria not only regulate energy metabolism, but also influence neuronal signaling. Regulation of "energy metabolism" and "neuronal signaling" (i.e. neurometabolic coupling), which are coupled rather than independent can be understood through mitochondria's integrative functions of calcium ion (Ca2+) uptake and cycling. While mitochondrial Ca2+ do not affect hemodynamics directly, neuronal activity changes are mechanistically linked to functional hyperemic responses (i.e. neurovascular coupling). Early in vitro studies lay the foundation of mitochondrial Ca2+ homeostasis and its functional roles within cells. However, recent in vivo approaches indicate mitochondrial Ca2+ homeostasis as maintained by the role of mitochondrial Ca2+ uniporter (mCU) influences system-level brain activity as measured by a variety of techniques. Based on earlier evidence of subcellular cytoplasmic Ca2+ microdomains and cellular bioenergetic states, a mechanistic model of Ca2+ mobilization is presented to understand systems-level neurovascular and neurometabolic coupling. This integrated view from molecular and cellular to the systems level, where mCU plays a major role in mitochondrial and cellular Ca2+ homeostasis, may explain the wide range of activation-induced coupling across neuronal activity, hemodynamic, and metabolic responses.
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23
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Groten CJ, Rebane JT, Hodgson HM, Chauhan AK, Blohm G, Magoski NS. Ca2+ removal by the plasma membrane Ca2+-ATPase influences the contribution of mitochondria to activity-dependent Ca2+ dynamics in Aplysia neuroendocrine cells. J Neurophysiol 2016; 115:2615-34. [PMID: 26864756 DOI: 10.1152/jn.00494.2015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 02/04/2016] [Indexed: 01/05/2023] Open
Abstract
After Ca(2+) influx, mitochondria can sequester Ca(2+) and subsequently release it back into the cytosol. This form of Ca(2+)-induced Ca(2+) release (CICR) prolongs Ca(2+) signaling and can potentially mediate activity-dependent plasticity. As Ca(2+) is required for its subsequent release, Ca(2+) removal systems, like the plasma membrane Ca(2+)-ATPase (PMCA), could impact CICR. Here we examine such a role for the PMCA in the bag cell neurons of Aplysia californica CICR is triggered in these neurons during an afterdischarge and is implicated in sustaining membrane excitability and peptide secretion. Somatic Ca(2+) was measured from fura-PE3-loaded cultured bag cell neurons recorded under whole cell voltage clamp. Voltage-gated Ca(2+) influx was elicited with a 5-Hz, 1-min train, which mimics the fast phase of the afterdischarge. PMCA inhibition with carboxyeosin or extracellular alkalization augmented the effectiveness of Ca(2+) influx in eliciting mitochondrial CICR. A Ca(2+) compartment model recapitulated these findings and indicated that disrupting PMCA-dependent Ca(2+) removal increases CICR by enhancing mitochondrial Ca(2+) loading. Indeed, carboxyeosin augmented train-evoked mitochondrial Ca(2+) uptake. Consistent with their role on Ca(2+) dynamics, cell labeling revealed that the PMCA and mitochondria overlap with Ca(2+) entry sites. Finally, PMCA-dependent Ca(2+) extrusion did not impact endoplasmic reticulum-dependent Ca(2+) removal or release, despite the organelle residing near Ca(2+) entry sites. Our results demonstrate that Ca(2+) removal by the PMCA influences the propensity for stimulus-evoked CICR by adjusting the amount of Ca(2+) available for mitochondrial Ca(2+) uptake. This study highlights a mechanism by which the PMCA could impact activity-dependent plasticity in the bag cell neurons.
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Affiliation(s)
- Christopher J Groten
- Department of Biomedical and Molecular Sciences, Physiology Graduate Program, Queen's University, Kingston, Ontario, Canada
| | - Jonathan T Rebane
- Department of Biomedical and Molecular Sciences, Physiology Graduate Program, Queen's University, Kingston, Ontario, Canada
| | - Heather M Hodgson
- Department of Biomedical and Molecular Sciences, Physiology Graduate Program, Queen's University, Kingston, Ontario, Canada
| | - Alamjeet K Chauhan
- Department of Biomedical and Molecular Sciences, Physiology Graduate Program, Queen's University, Kingston, Ontario, Canada
| | - Gunnar Blohm
- Department of Biomedical and Molecular Sciences, Physiology Graduate Program, Queen's University, Kingston, Ontario, Canada
| | - Neil S Magoski
- Department of Biomedical and Molecular Sciences, Physiology Graduate Program, Queen's University, Kingston, Ontario, Canada
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Golpour A, Pšenička M, Niksirat H. Subcellular localization of calcium deposits during zebrafish (Danio rerio) oogenesis. Micron 2016; 80:6-13. [DOI: 10.1016/j.micron.2015.09.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 09/04/2015] [Indexed: 10/23/2022]
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Lukyanova LD, Kirova YI. Mitochondria-controlled signaling mechanisms of brain protection in hypoxia. Front Neurosci 2015; 9:320. [PMID: 26483619 PMCID: PMC4589588 DOI: 10.3389/fnins.2015.00320] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 08/27/2015] [Indexed: 01/06/2023] Open
Abstract
The article is focused on the role of the cell bioenergetic apparatus, mitochondria, involved in development of immediate and delayed molecular mechanisms for adaptation to hypoxic stress in brain cortex. Hypoxia induces reprogramming of respiratory chain function and switching from oxidation of NAD-related substrates (complex I) to succinate oxidation (complex II). Transient, reversible, compensatory activation of respiratory chain complex II is a major mechanism of immediate adaptation to hypoxia necessary for (1) succinate-related energy synthesis in the conditions of oxygen deficiency and formation of urgent resistance in the body; (2) succinate-related stabilization of HIF-1α and initiation of its transcriptional activity related with formation of long-term adaptation; (3) succinate-related activation of the succinate-specific receptor, GPR91. This mechanism participates in at least four critical regulatory functions: (1) sensor function related with changes in kinetic properties of complex I and complex II in response to a gradual decrease in ambient oxygen concentration; this function is designed for selection of the most efficient pathway for energy substrate oxidation in hypoxia; (2) compensatory function focused on formation of immediate adaptive responses to hypoxia and hypoxic resistance of the body; (3) transcriptional function focused on activated synthesis of HIF-1 and the genes providing long-term adaptation to low pO2; (4) receptor function, which reflects participation of mitochondria in the intercellular signaling system via the succinate-dependent receptor, GPR91. In all cases, the desired result is achieved by activation of the succinate-dependent oxidation pathway, which allows considering succinate as a signaling molecule. Patterns of mitochondria-controlled activation of GPR-91- and HIF-1-dependent reaction were considered, and a possibility of their participation in cellular-intercellular-systemic interactions in hypoxia and adaptation was proved.
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Affiliation(s)
- Ludmila D. Lukyanova
- Laboratory for Bioenergetics and Hypoxia, Institute of General Pathology and PathophysiologyMoscow, Russia
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26
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The roads to mitochondrial dysfunction in a rat model of posttraumatic syringomyelia. BIOMED RESEARCH INTERNATIONAL 2015; 2015:831490. [PMID: 25685811 PMCID: PMC4309244 DOI: 10.1155/2015/831490] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 10/13/2014] [Indexed: 11/26/2022]
Abstract
The pathophysiology of posttraumatic syringomyelia is incompletely understood. We examined whether local ischemia occurs after spinal cord injury. If so, whether it causes neuronal mitochondrial dysfunction and depletion, and subsequent energy metabolism impairment results in cell starvation of energy and even cell death, contributing to the enlargement of the cavity. Local blood flow was measured in a rat model of posttraumatic syringomyelia that had received injections of quisqualic acid and kaolin. We found an 86 ± 11% reduction of local blood flow at C8 where a cyst formed at 6 weeks after syrinx induction procedure (P < 0.05), and no difference in blood flow rate between the laminectomy and intact controls. Electron microscopy confirmed irreversible neuronal mitochondrion depletion surrounding the cyst, but recoverable mitochondrial loses in laminectomy rats. Profound energy loss quantified in the spinal cord of syrinx animals, and less ATP and ADP decline observed in laminectomy rats. Our findings demonstrate that an excitotoxic injury induces local ischemia in the spinal cord and results in neuronal mitochondrial depletion, and profound ATP loss, contributing to syrinx enlargement. Ischemia did not occur following laminectomy induced trauma in which mitochondrial loss and decline in ATP were reversible. This confirms excitotoxic injury contributing to the pathology of posttraumatic syringomyelia.
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27
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The mitochondrial Ca(2+) uniporter complex. J Mol Cell Cardiol 2014; 78:3-8. [PMID: 25463276 DOI: 10.1016/j.yjmcc.2014.11.015] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Revised: 11/13/2014] [Accepted: 11/14/2014] [Indexed: 01/09/2023]
Abstract
Calcium influx into the mitochondrial matrix plays important roles in the regulation of cell death pathways, bioenergetics and cytoplasmic Ca(2+) signals. During the last few years, several molecular components of the inner membrane mitochondrial Ca(2+) uniporter, the dominant pathway for Ca(2+) influx into the mitochondrial matrix, have been identified. The uniporter is now recognized as a complex of proteins that include a Ca(2+) pore forming component and accessory proteins that are either required for its channel activity or regulate it under various conditions. This review summarizes recent discoveries about the molecular basis of the uniporter complex. This article is part of a Special Issue entitled "Mitochondria: From Basic Mitochondrial Biology to Cardiovascular Disease."
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Li Q, Guo HC, Maslov LN, Qiao XW, Zhou JJ, Zhang Y. Mitochondrial permeability transition pore plays a role in the cardioprotection of CB2 receptor against ischemia–reperfusion injury. Can J Physiol Pharmacol 2014; 92:205-14. [DOI: 10.1139/cjpp-2013-0293] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this study was to investigate whether the mitochondrial permeability transition pore (MPTP) opening was involved in the protective effects of CB2 receptor against ischemia–reperfusion (I-R) injury. For this, isolated perfused rat hearts were subjected to 30 min global ischemia followed by 120 min reperfusion, and left ventricle function was recorded. At the end of reperfusion, the infarct size in the hearts was measured by staining with triphenyltetrazolium chloride. MPTP opening and the mitochondrial membrane potential (ΔΨm) were measured by flow cytometry. Western blot analysis of cytochrome c in the mitochondrion and cytosol, as well as ERK1/2 and p-ERK1/2 were performed. Administration of CB2 receptor agonist JWH133 before ischemia significantly improved the recovery of cardiac ventricular function during reperfusion, increased coronary flow, reduced infarct size, prevented the loss of ΔΨm and MPTP opening, reduced the release of cytochrome c from mitochondria, and increased levels of p-ERK1/2. These effects of JWH133 were abolished by pretreatment with CB2 receptor antagonist AM630, or ERK1/2 inhibitor PD98059. Furthermore, JWH133 reversed the MPTP opening induced by atractyloside. The protective effect of JWH133 on the heart against I-R injury may be through increased ERK1/2 phosphorylation, inhibiting MPTP opening.
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Affiliation(s)
- Qian Li
- Department of Physiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Hui-cai Guo
- Department of Toxicology, Hebei Medical University, Shijiazhuang 050017, China
| | - Leonid N. Maslov
- Institute of Cardiology of the Siberian Branch of the Russian Academy of Medical Sciences, Tomsk 634012, Russia
| | - Xiao-wen Qiao
- Department of Pediatrics, Xinji City Hospital of traditional Chinese Medicine, Xinji 052360, China
| | - Jing-jing Zhou
- Department of Physiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Yi Zhang
- Department of Physiology, Hebei Medical University, Shijiazhuang 050017, China
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Separate Ca2+ sources are buffered by distinct Ca2+ handling systems in aplysia neuroendocrine cells. J Neurosci 2013; 33:6476-91. [PMID: 23575846 DOI: 10.1523/jneurosci.6384-11.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Although the contribution of Ca(2+) buffering systems can vary between neuronal types and cellular compartments, it is unknown whether distinct Ca(2+) sources within a neuron have different buffers. As individual Ca(2+) sources can have separate functions, we propose that each is handled by unique systems. Using Aplysia californica bag cell neurons, which initiate reproduction through an afterdischarge involving multiple Ca(2+)-dependent processes, we investigated the role of endoplasmic reticulum (ER) and mitochondrial sequestration, as well as extrusion via the plasma membrane Ca(2+)-ATPase (PMCA) and Na(+)/Ca(2+) exchanger, to the clearance of voltage-gated Ca(2+) influx, Ca(2+)-induced Ca(2+)-release (CICR), and store-operated Ca(2+) influx. Cultured bag cell neurons were filled with the Ca(2+) indicator, fura-PE3, to image Ca(2+) under whole-cell voltage clamp. A 5 Hz, 1 min train of depolarizing voltage steps elicited voltage-gated Ca(2+) influx followed by EGTA-sensitive CICR from the mitochondria. A compartment model of Ca(2+) indicated the effect of EGTA on CICR was due to buffering of released mitochondrial Ca(2+) rather than uptake competition. Removal of voltage-gated Ca(2+) influx was dominated by the mitochondria and PMCA, with no contribution from the Na(+)/Ca(2+) exchanger or sarcoplasmic/endoplasmic Ca(2+)-ATPase (SERCA). In contrast, CICR recovery was slowed by eliminating the Na(+)/Ca(2+) exchanger and PMCA. Last, store-operated influx, evoked by ER depletion, was removed by the SERCA and depended on the mitochondrial membrane potential. Our results demonstrate that distinct buffering systems are dedicated to particular Ca(2+) sources. In general, this may represent a means to differentially regulate Ca(2+)-dependent processes, and for Aplysia, influence how reproductive behavior is triggered.
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Mallilankaraman K, Doonan P, Cárdenas C, Chandramoorthy HC, Müller M, Miller R, Hoffman NE, Gandhirajan RK, Molgó J, Birnbaum MJ, Rothberg BS, Mak DOD, Foskett JK, Madesh M. MICU1 is an essential gatekeeper for MCU-mediated mitochondrial Ca(2+) uptake that regulates cell survival. Cell 2013; 151:630-44. [PMID: 23101630 DOI: 10.1016/j.cell.2012.10.011] [Citation(s) in RCA: 487] [Impact Index Per Article: 44.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 07/30/2012] [Accepted: 10/05/2012] [Indexed: 12/18/2022]
Abstract
Mitochondrial Ca(2+) (Ca(2+)(m)) uptake is mediated by an inner membrane Ca(2+) channel called the uniporter. Ca(2+) uptake is driven by the considerable voltage present across the inner membrane (ΔΨ(m)) generated by proton pumping by the respiratory chain. Mitochondrial matrix Ca(2+) concentration is maintained five to six orders of magnitude lower than its equilibrium level, but the molecular mechanisms for how this is achieved are not clear. Here, we demonstrate that the mitochondrial protein MICU1 is required to preserve normal [Ca(2+)](m) under basal conditions. In its absence, mitochondria become constitutively loaded with Ca(2+), triggering excessive reactive oxygen species generation and sensitivity to apoptotic stress. MICU1 interacts with the uniporter pore-forming subunit MCU and sets a Ca(2+) threshold for Ca(2+)(m) uptake without affecting the kinetic properties of MCU-mediated Ca(2+) uptake. Thus, MICU1 is a gatekeeper of MCU-mediated Ca(2+)(m) uptake that is essential to prevent [Ca(2+)](m) overload and associated stress.
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Dedkova EN, Blatter LA. Calcium signaling in cardiac mitochondria. J Mol Cell Cardiol 2013; 58:125-33. [PMID: 23306007 DOI: 10.1016/j.yjmcc.2012.12.021] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 12/01/2012] [Accepted: 12/28/2012] [Indexed: 01/02/2023]
Abstract
Mitochondrial Ca signaling contributes to the regulation of cellular energy metabolism, and mitochondria participate in cardiac excitation-contraction coupling (ECC) through their ability to store Ca, shape the cytosolic Ca signals and generate ATP required for contraction. The mitochondrial inner membrane is equipped with an elaborate system of channels and transporters for Ca uptake and extrusion that allows for the decoding of cytosolic Ca signals, and the storage of Ca in the mitochondrial matrix compartment. Controversy, however remains whether the fast cytosolic Ca transients underlying ECC in the beating heart are transmitted rapidly into the matrix compartment or slowly integrated by the mitochondrial Ca transport machinery. This review summarizes established and novel findings on cardiac mitochondrial Ca transport and buffering, and discusses the evidence either supporting or arguing against the idea that Ca can be taken up rapidly by mitochondria during ECC.
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Affiliation(s)
- Elena N Dedkova
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, IL 60612, USA
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33
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Hou T, Zhang X, Xu J, Jian C, Huang Z, Ye T, Hu K, Zheng M, Gao F, Wang X, Cheng H. Synergistic triggering of superoxide flashes by mitochondrial Ca2+ uniport and basal reactive oxygen species elevation. J Biol Chem 2013; 288:4602-12. [PMID: 23283965 DOI: 10.1074/jbc.m112.398297] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mitochondrial superoxide flashes reflect a quantal, bursting mode of reactive oxygen species (ROS) production that arises from stochastic, transient opening of the mitochondrial permeability transition pore (mPTP) in many types of cells and in living animals. However, the regulatory mechanisms and the exact nature of the flash-coupled mPTP remain poorly understood. Here we demonstrate a profound synergistic effect between mitochondrial Ca(2+) uniport and elevated basal ROS production in triggering superoxide flashes in intact cells. Hyperosmotic stress potently augmented the flash activity while simultaneously elevating mitochondrial Ca(2+) and ROS. Blocking mitochondrial Ca(2+) transport by knockdown of MICU1 or MCU, newly identified components of the mitochondrial Ca(2+) uniporter, or scavenging mitochondrial basal ROS markedly diminished the flash response. More importantly, whereas elevating Ca(2+) or ROS production alone was inefficacious in triggering the flashes, concurrent physiological Ca(2+) and ROS elevation served as the most powerful flash activator, increasing the flash incidence by an order of magnitude. Functionally, superoxide flashes in response to hyperosmotic stress participated in the activation of JNK and p38. Thus, physiological levels of mitochondrial Ca(2+) and ROS synergistically regulate stochastic mPTP opening and quantal ROS production in intact cells, marking the flash as a coincidence detector of mitochondrial Ca(2+) and ROS signals.
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Affiliation(s)
- Tingting Hou
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
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Choo HJ, Saafir TB, Mkumba L, Wagner MB, Jobe SM. Mitochondrial calcium and reactive oxygen species regulate agonist-initiated platelet phosphatidylserine exposure. Arterioscler Thromb Vasc Biol 2012; 32:2946-55. [PMID: 23087357 PMCID: PMC3545632 DOI: 10.1161/atvbaha.112.300433] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To study the interactions of cytoplasmic calcium elevation, mitochondrial permeability transition pore (mPTP) formation, and reactive oxygen species formation in the regulation of phosphatidylserine (PS) exposure in platelets. METHODS AND RESULTS mPTP formation, but not the degree of cytoplasmic calcium elevation, was associated with PS exposure in wild-type, cyclophilin D-null, ionomycin-treated, and reactive oxygen species-treated platelets. In the absence of the mPTP regulator cyclophilin D, agonist-initiated mPTP formation and high-level PS exposure were markedly blunted, but cytoplasmic calcium transients were unchanged. Mitochondrial calcium (Ca(2+)(mit)) transients and reactive oxygen species, key regulators of mPTP formation, were examined in strongly stimulated platelets. Increased reactive oxygen species production occurred in strongly stimulated platelets and was dependent on extracellular calcium entry, but not the presence of cyclophilin D. Ca(2+)(mit) increased significantly in strongly stimulated platelets. Abrogation of Ca(2+)(mit) entry, either by inhibition of the Ca(2+)(mit) uniporter or mitochondrial depolarization, prevented mPTP formation and exposure but not platelet aggregation or granule release. CONCLUSIONS Sustained cytoplasmic calcium levels are necessary, but not sufficient, for high-level PS exposure in response to agonists. Increased Ca(2+)(mit) levels are a key signal initiating mPTP formation and PS exposure. Blockade of Ca(2+)(mit) entry allows the specific inhibition of platelet procoagulant activity.
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Affiliation(s)
- Hyo-Jung Choo
- Department of Pediatrics, Aflac Cancer Center and Blood Disorders Service, Emory University and Children’s Healthcare of Atlanta
| | - Talib B. Saafir
- Department of Pediatrics, Sibley Heart Center, Emory University and Children’s Healthcare of Atlanta
| | - Laura Mkumba
- Department of Pediatrics, Aflac Cancer Center and Blood Disorders Service, Emory University and Children’s Healthcare of Atlanta
| | - Mary B. Wagner
- Department of Pediatrics, Sibley Heart Center, Emory University and Children’s Healthcare of Atlanta
| | - Shawn M. Jobe
- Department of Pediatrics, Aflac Cancer Center and Blood Disorders Service, Emory University and Children’s Healthcare of Atlanta
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Mallilankaraman K, Cárdenas C, Doonan PJ, Chandramoorthy HC, Irrinki KM, Golenár T, Csordás G, Madireddi P, Yang J, Müller M, Miller R, Kolesar JE, Molgó J, Kaufman B, Hajnóczky G, Foskett JK, Madesh M. MCUR1 is an essential component of mitochondrial Ca2+ uptake that regulates cellular metabolism. Nat Cell Biol 2012. [PMID: 23178883 PMCID: PMC3511605 DOI: 10.1038/ncb2622] [Citation(s) in RCA: 413] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Ca(2+) flux across the mitochondrial inner membrane regulates bioenergetics, cytoplasmic Ca(2+) signals and activation of cell death pathways. Mitochondrial Ca(2+) uptake occurs at regions of close apposition with intracellular Ca(2+) release sites, driven by the inner membrane voltage generated by oxidative phosphorylation and mediated by a Ca(2+) selective ion channel (MiCa; ref. ) called the uniporter whose complete molecular identity remains unknown. Mitochondrial calcium uniporter (MCU) was recently identified as the likely ion-conducting pore. In addition, MICU1 was identified as a mitochondrial regulator of uniporter-mediated Ca(2+) uptake in HeLa cells. Here we identified CCDC90A, hereafter referred to as MCUR1 (mitochondrial calcium uniporter regulator 1), an integral membrane protein required for MCU-dependent mitochondrial Ca(2+) uptake. MCUR1 binds to MCU and regulates ruthenium-red-sensitive MCU-dependent Ca(2+) uptake. MCUR1 knockdown does not alter MCU localization, but abrogates Ca(2+) uptake by energized mitochondria in intact and permeabilized cells. Ablation of MCUR1 disrupts oxidative phosphorylation, lowers cellular ATP and activates AMP kinase-dependent pro-survival autophagy. Thus, MCUR1 is a critical component of a mitochondrial uniporter channel complex required for mitochondrial Ca(2+) uptake and maintenance of normal cellular bioenergetics.
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Pangare M, Makino A. Mitochondrial function in vascular endothelial cell in diabetes. J Smooth Muscle Res 2012; 48:1-26. [PMID: 22504486 DOI: 10.1540/jsmr.48.1] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Micro- and macrovascular complications are commonly seen in diabetic patients and endothelial dysfunction contributes to the development and progression of the complications. Abnormal functions in endothelial cells lead to the increase in vascular tension and atherosclerosis, followed by systemic hypertension as well as increased incidence of ischemia and stroke in diabetic patients. Mitochondria are organelles serving as a source of energy production and as regulators of cell survival (e.g., apoptosis and cell development) and ion homeostasis (e.g., H(+), Ca(2+)). Endothelial mitochondria are mainly responsible for generation of reactive oxygen species (ROS) and maintaining the Ca(2+) concentration in the cytosol. There is increasing evidence that mitochondrial morphological and functional changes are implicated in vascular endothelial dysfunction. Enhanced mitochondrial fission and/or attenuated fusion lead to mitochondrial fragmentation and disrupt the endothelial physiological function. Abnormal mitochondrial biogenesis and disturbance of mitochondrial autophagy increase the accumulation of damaged mitochondria, such as irreversibly depolarized or leaky mitochondria, and facilitate cell death. Augmented mitochondrial ROS production and Ca(2+) overload in mitochondria not only cause the maladaptive effect on the endothelial function, but also are potentially detrimental to cell survival. In this article, we review the physiological and pathophysiological role of mitochondria in endothelial function with special focus on diabetes.
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Affiliation(s)
- Meenal Pangare
- University of Illinois at Chicago, Chicago, IL 60612, USA
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Role of calcium and mitochondria in MeHg-mediated cytotoxicity. J Biomed Biotechnol 2012; 2012:248764. [PMID: 22927718 PMCID: PMC3425894 DOI: 10.1155/2012/248764] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 06/12/2012] [Accepted: 06/14/2012] [Indexed: 11/17/2022] Open
Abstract
Methylmercury (MeHg) mediated cytotoxicity is associated with loss of intracellular calcium (Ca2+) homeostasis. The imbalance in Ca2+ physiology is believed to be associated with dysregulation of Ca2+ intracellular stores and/or increased permeability of the biomembranes to this ion. In this paper we summarize the contribution of glutamate dyshomeostasis in intracellular Ca2+ overload and highlight the mitochondrial dysfunctions induced by MeHg via Ca2+ overload. Mitochondrial disturbances elicited by Ca2+ may involve several molecular events (i.e., alterations in the activity of the mitochondrial electron transport chain complexes, mitochondrial proton gradient dissipation, mitochondrial permeability transition pore (MPTP) opening, thiol depletion, failure of energy metabolism, reactive oxygen species overproduction) that could culminate in cell death. Here we will focus on the role of oxidative stress in these phenomena. Additionally, possible antioxidant therapies that could be effective in the treatment of MeHg intoxication are briefly discussed.
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Ge H, Tollner TL, Hu Z, Dai M, Li X, Guan H, Shan D, Zhang X, Lv J, Huang C, Dong Q. The importance of mitochondrial metabolic activity and mitochondrial DNA replication during oocyte maturation in vitro on oocyte quality and subsequent embryo developmental competence. Mol Reprod Dev 2012; 79:392-401. [DOI: 10.1002/mrd.22042] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 03/25/2012] [Indexed: 11/09/2022]
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Zhou L, O'Rourke B. Cardiac mitochondrial network excitability: insights from computational analysis. Am J Physiol Heart Circ Physiol 2012; 302:H2178-89. [PMID: 22427517 DOI: 10.1152/ajpheart.01073.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In the heart, mitochondria form a regular lattice and function as a coordinated, nonlinear network to continuously produce ATP to meet the high-energy demand of the cardiomyocytes. Cardiac mitochondria also exhibit properties of an excitable system: electrical or chemical signals can spread within or among cells in the syncytium. The detailed mechanisms by which signals pass among individual elements (mitochondria) across the network are still not completely understood, although emerging studies suggest that network excitability might be mediated by the local diffusion and autocatalytic release of messenger molecules such as reactive oxygen species and/or Ca(2+). In this short review, we have attempted to described recent advances in the field of cardiac mitochondrial network excitability. Specifically, we have focused on how mitochondria communicate with each other through the diffusion and regeneration of messenger molecules to initiate and propagate waves or oscillations, as revealed by computational models of mitochondrial network.
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Affiliation(s)
- Lufang Zhou
- Division of Cardiovascular Disease, Department of Medicine, The University of Alabama at Birmingham, 35294, USA.
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Ultrastructural characterization of porcine oocytes and adjacent follicular cells during follicle development: Lipid component evolution. Theriogenology 2011; 76:1647-57. [DOI: 10.1016/j.theriogenology.2011.06.029] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 06/24/2011] [Accepted: 06/25/2011] [Indexed: 11/22/2022]
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Verma A, Bhatt AN, Farooque A, Khanna S, Singh S, Dwarakanath BS. Calcium ionophore A23187 reveals calcium related cellular stress as “I-Bodies”: An old actor in a new role. Cell Calcium 2011; 50:510-22. [DOI: 10.1016/j.ceca.2011.08.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 08/28/2011] [Accepted: 08/29/2011] [Indexed: 12/22/2022]
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Trypanosomes and the solution to a 50-year mitochondrial calcium mystery. Trends Parasitol 2011; 28:31-7. [PMID: 22088944 DOI: 10.1016/j.pt.2011.10.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 10/19/2011] [Accepted: 10/19/2011] [Indexed: 12/29/2022]
Abstract
The ability of mitochondria to take up Ca(2+) was discovered 50 years ago. This calcium uptake, through a mitochondrial calcium uniporter (MCU), is important not only for the regulation of cellular ATP concentration but also for more complex pathways such as shaping Ca(2+) signals and the activation of programmed cell death. The molecular nature of the uniporter remained unknown for decades. By a comparative study of mitochondrial protein profiles of organisms lacking or possessing MCU, such as yeast in the former case and vertebrates and trypanosomes in the latter, two groups recently found the protein that possesses all the characteristics of the MCU. These results add another success story to the already substantial contributions of trypanosomes to mammalian biochemistry.
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Napolioni V, Persico AM, Porcelli V, Palmieri L. The mitochondrial aspartate/glutamate carrier AGC1 and calcium homeostasis: physiological links and abnormalities in autism. Mol Neurobiol 2011; 44:83-92. [PMID: 21691713 DOI: 10.1007/s12035-011-8192-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Accepted: 06/02/2011] [Indexed: 10/18/2022]
Abstract
Autism spectrum disorder (ASD) is a severe, complex neurodevelopmental disorder characterized by impairments in reciprocal social interaction and communication, and restricted and stereotyped patterns of interests and behaviors. Recent evidence has unveiled an important role for calcium (Ca(2+)) signaling in the pathogenesis of ASD. Post-mortem studies of autistic brains have pointed toward abnormalities in mitochondrial function as possible downstream consequences of altered Ca(2+) signaling, abnormal synapse formation, and dysreactive immunity. SLC25A12, an ASD susceptibility gene, encodes the Ca(2+)-regulated mitochondrial aspartate-glutamate carrier, isoform 1 (AGC1). AGC1 is an important component of the malate/aspartate shuttle, a crucial system supporting oxidative phosphorylation and adenosine triphosphate (ATP) production. Here, we review the physiological roles of AGC1, its links to calcium homeostasis, and its involvement in autism pathogenesis.
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Affiliation(s)
- Valerio Napolioni
- Laboratory of Molecular Psychiatry & Neurogenetics, University Campus Bio-Medico, Via Alvaro del Portillo 21, 00128 Rome, Italy
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Integrative genomics identifies MCU as an essential component of the mitochondrial calcium uniporter. Nature 2011; 476:341-5. [PMID: 21685886 DOI: 10.1038/nature10234] [Citation(s) in RCA: 1424] [Impact Index Per Article: 109.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 06/02/2011] [Indexed: 12/19/2022]
Abstract
Mitochondria from diverse organisms are capable of transporting large amounts of Ca(2+) via a ruthenium-red-sensitive, membrane-potential-dependent mechanism called the uniporter. Although the uniporter's biophysical properties have been studied extensively, its molecular composition remains elusive. We recently used comparative proteomics to identify MICU1 (also known as CBARA1), an EF-hand-containing protein that serves as a putative regulator of the uniporter. Here, we use whole-genome phylogenetic profiling, genome-wide RNA co-expression analysis and organelle-wide protein coexpression analysis to predict proteins functionally related to MICU1. All three methods converge on a novel predicted transmembrane protein, CCDC109A, that we now call 'mitochondrial calcium uniporter' (MCU). MCU forms oligomers in the mitochondrial inner membrane, physically interacts with MICU1, and resides within a large molecular weight complex. Silencing MCU in cultured cells or in vivo in mouse liver severely abrogates mitochondrial Ca(2+) uptake, whereas mitochondrial respiration and membrane potential remain fully intact. MCU has two predicted transmembrane helices, which are separated by a highly conserved linker facing the intermembrane space. Acidic residues in this linker are required for its full activity. However, an S259A point mutation retains function but confers resistance to Ru360, the most potent inhibitor of the uniporter. Our genomic, physiological, biochemical and pharmacological data firmly establish MCU as an essential component of the mitochondrial Ca(2+) uniporter.
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Zhdanov AV, Dmitriev RI, Papkovsky DB. Bafilomycin A1 activates respiration of neuronal cells via uncoupling associated with flickering depolarization of mitochondria. Cell Mol Life Sci 2010; 68:903-17. [PMID: 20820851 PMCID: PMC3037485 DOI: 10.1007/s00018-010-0502-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 07/08/2010] [Accepted: 08/06/2010] [Indexed: 10/27/2022]
Abstract
Bafilomycin A1 (Baf) induces an elevation of cytosolic Ca(2+) and acidification in neuronal cells via inhibition of the V-ATPase. Also, Baf uncouples mitochondria in differentiated PC12 ((d)PC12), (d)SH-SY5Y cells and cerebellar granule neurons, and markedly elevates their respiration. This respiratory response in (d)PC12 is accompanied by morphological changes in the mitochondria and decreases the mitochondrial pH, Ca(2+) and ΔΨm. The response to Baf is regulated by cytosolic Ca(2+) fluxes from the endoplasmic reticulum. Inhibition of permeability transition pore opening increases the depolarizing effect of Baf on the ΔΨm. Baf induces stochastic flickering of the ΔΨm with a period of 20 ± 10 s. Under conditions of suppressed ATP production by glycolysis, oxidative phosphorylation impaired by Baf does not provide cells with sufficient ATP levels. Cells treated with Baf become more susceptible to excitation with KCl. Such mitochondrial uncoupling may play a role in a number of (patho)physiological conditions induced by Baf.
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Affiliation(s)
- Alexander V Zhdanov
- Biochemistry Department, University College Cork, Cavanagh Pharmacy Building, College Road, Cork, Republic of Ireland.
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MICU1 encodes a mitochondrial EF hand protein required for Ca(2+) uptake. Nature 2010; 467:291-6. [PMID: 20693986 PMCID: PMC2977980 DOI: 10.1038/nature09358] [Citation(s) in RCA: 667] [Impact Index Per Article: 47.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Accepted: 07/19/2010] [Indexed: 02/07/2023]
Abstract
Mitochondrial calcium uptake plays a central role in cell physiology by stimulating ATP production, shaping cytosolic calcium transients, and regulating cell death. The biophysical properties of mitochondrial calcium uptake have been studied in detail, but the underlying proteins remain elusive. Here, we utilize an integrative strategy to predict human genes involved in mitochondrial calcium entry based on clues from comparative physiology, evolutionary genomics, and organelle proteomics. RNA interference against 13 top candidates highlighted one gene that we now call mitochondrial calcium uptake 1 (MICU1). Silencing MICU1 does not disrupt mitochondrial respiration or membrane potential but abolishes mitochondrial calcium entry in intact and permeabilized cells, and attenuates the metabolic coupling between cytosolic calcium transients and activation of matrix dehydrogenases. MICU1 is associated with the organelle’s inner membrane and has two canonical EF hands that are essential for its activity, suggesting a role in calcium sensing. MICU1 represents the founding member of a set of proteins required for high capacity mitochondrial calcium entry. Its discovery may lead to the complete molecular characterization of mitochondrial calcium uptake pathways, and offers genetic strategies for understanding their contribution to normal physiology and disease.
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Contreras L, Drago I, Zampese E, Pozzan T. Mitochondria: the calcium connection. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:607-18. [PMID: 20470749 DOI: 10.1016/j.bbabio.2010.05.005] [Citation(s) in RCA: 252] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 05/04/2010] [Accepted: 05/04/2010] [Indexed: 12/21/2022]
Abstract
Calcium handling by mitochondria is a key feature in cell life. It is involved in energy production for cell activity, in buffering and shaping cytosolic calcium rises and also in determining cell fate by triggering or preventing apoptosis. Both mitochondria and the mechanisms involved in the control of calcium homeostasis have been extensively studied, but they still provide researchers with long-standing or even new challenges. Technical improvements in the tools employed for the investigation of calcium dynamics have been-and are still-opening new perspectives in this field, and more prominently for mitochondria. In this review we present a state-of-the-art toolkit for calcium measurements, with major emphasis on the advantages of genetically encoded indicators. These indicators can be efficiently and selectively targeted to specific cellular sub-compartments, allowing previously unavailable high-definition calcium dynamic studies. We also summarize the main features of cellular and, in more detail, mitochondrial calcium handling, especially focusing on the latest breakthroughs in the field, such as the recent direct characterization of the calcium microdomains that occur on the mitochondrial surface upon cellular stimulation. Additionally, we provide a major example of the key role played by calcium in patho-physiology by briefly describing the extensively reported-albeit highly controversial-alterations of calcium homeostasis in Alzheimer's disease, casting lights on the possible alterations in mitochondrial calcium handling in this pathology.
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Affiliation(s)
- Laura Contreras
- Department of Biomedical Sciences, University of Padua, Italy.
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Ye H, Cotic M, Kang EE, Fehlings MG, Carlen PL. Transmembrane potential induced on the internal organelle by a time-varying magnetic field: a model study. J Neuroeng Rehabil 2010; 7:12. [PMID: 20170538 PMCID: PMC2836366 DOI: 10.1186/1743-0003-7-12] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Accepted: 02/20/2010] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND When a cell is exposed to a time-varying magnetic field, this leads to an induced voltage on the cytoplasmic membrane, as well as on the membranes of the internal organelles, such as mitochondria. These potential changes in the organelles could have a significant impact on their functionality. However, a quantitative analysis on the magnetically-induced membrane potential on the internal organelles has not been performed. METHODS Using a two-shell model, we provided the first analytical solution for the transmembrane potential in the organelle membrane induced by a time-varying magnetic field. We then analyzed factors that impact on the polarization of the organelle, including the frequency of the magnetic field, the presence of the outer cytoplasmic membrane, and electrical and geometrical parameters of the cytoplasmic membrane and the organelle membrane. RESULTS The amount of polarization in the organelle was less than its counterpart in the cytoplasmic membrane. This was largely due to the presence of the cell membrane, which "shielded" the internal organelle from excessive polarization by the field. Organelle polarization was largely dependent on the frequency of the magnetic field, and its polarization was not significant under the low frequency band used for transcranial magnetic stimulation (TMS). Both the properties of the cytoplasmic and the organelle membranes affect the polarization of the internal organelle in a frequency-dependent manner. CONCLUSIONS The work provided a theoretical framework and insights into factors affecting mitochondrial function under time-varying magnetic stimulation, and provided evidence that TMS does not affect normal mitochondrial functionality by altering its membrane potential.
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Affiliation(s)
- Hui Ye
- Toronto Western Research Institute, University Health Network, Ontario, Canada .
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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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