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Sanders KM, Drumm BT, Cobine CA, Baker SA. Ca 2+ dynamics in interstitial cells: foundational mechanisms for the motor patterns in the gastrointestinal tract. Physiol Rev 2024; 104:329-398. [PMID: 37561138 DOI: 10.1152/physrev.00036.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 06/29/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023] Open
Abstract
The gastrointestinal (GI) tract displays multiple motor patterns that move nutrients and wastes through the body. Smooth muscle cells (SMCs) provide the forces necessary for GI motility, but interstitial cells, electrically coupled to SMCs, tune SMC excitability, transduce inputs from enteric motor neurons, and generate pacemaker activity that underlies major motor patterns, such as peristalsis and segmentation. The interstitial cells regulating SMCs are interstitial cells of Cajal (ICC) and PDGF receptor (PDGFR)α+ cells. Together these cells form the SIP syncytium. ICC and PDGFRα+ cells express signature Ca2+-dependent conductances: ICC express Ca2+-activated Cl- channels, encoded by Ano1, that generate inward current, and PDGFRα+ cells express Ca2+-activated K+ channels, encoded by Kcnn3, that generate outward current. The open probabilities of interstitial cell conductances are controlled by Ca2+ release from the endoplasmic reticulum. The resulting Ca2+ transients occur spontaneously in a stochastic manner. Ca2+ transients in ICC induce spontaneous transient inward currents and spontaneous transient depolarizations (STDs). Neurotransmission increases or decreases Ca2+ transients, and the resulting depolarizing or hyperpolarizing responses conduct to other cells in the SIP syncytium. In pacemaker ICC, STDs activate voltage-dependent Ca2+ influx, which initiates a cluster of Ca2+ transients and sustains activation of ANO1 channels and depolarization during slow waves. Regulation of GI motility has traditionally been described as neurogenic and myogenic. Recent advances in understanding Ca2+ handling mechanisms in interstitial cells and how these mechanisms influence motor patterns of the GI tract suggest that the term "myogenic" should be replaced by the term "SIPgenic," as this review discusses.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada-Reno, Reno, Nevada, United States
| | - Bernard T Drumm
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Caroline A Cobine
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Salah A Baker
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada-Reno, Reno, Nevada, United States
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2
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Silvestri R, Nicolì V, Gangadharannambiar P, Crea F, Bootman MD. Calcium signalling pathways in prostate cancer initiation and progression. Nat Rev Urol 2023; 20:524-543. [PMID: 36964408 DOI: 10.1038/s41585-023-00738-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/06/2023] [Indexed: 03/26/2023]
Abstract
Cancer cells proliferate, differentiate and migrate by repurposing physiological signalling mechanisms. In particular, altered calcium signalling is emerging as one of the most widespread adaptations in cancer cells. Remodelling of calcium signalling promotes the development of several malignancies, including prostate cancer. Gene expression data from in vitro, in vivo and bioinformatics studies using patient samples and xenografts have shown considerable changes in the expression of various components of the calcium signalling toolkit during the development of prostate cancer. Moreover, preclinical and clinical evidence suggests that altered calcium signalling is a crucial component of the molecular re-programming that drives prostate cancer progression. Evidence points to calcium signalling re-modelling, commonly involving crosstalk between calcium and other cellular signalling pathways, underpinning the onset and temporal progression of this disease. Discrete alterations in calcium signalling have been implicated in hormone-sensitive, castration-resistant and aggressive variant forms of prostate cancer. Hence, modulation of calcium signals and downstream effector molecules is a plausible therapeutic strategy for both early and late stages of prostate cancer. Based on this premise, clinical trials have been undertaken to establish the feasibility of targeting calcium signalling specifically for prostate cancer.
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Affiliation(s)
| | - Vanessa Nicolì
- Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Pisa, Italy
| | | | - Francesco Crea
- Cancer Research Group, School of Life Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Martin D Bootman
- Cancer Research Group, School of Life Health and Chemical Sciences, The Open University, Milton Keynes, UK.
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3
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Cho E, Woo Y, Suh Y, Suh BK, Kim SJ, Nhung TTM, Yoo JY, Nghi TD, Lee SB, Mun DJ, Park SK. Ratiometric measurement of MAM Ca 2+ dynamics using a modified CalfluxVTN. Nat Commun 2023; 14:3586. [PMID: 37328454 PMCID: PMC10276021 DOI: 10.1038/s41467-023-39343-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 06/06/2023] [Indexed: 06/18/2023] Open
Abstract
Mitochondria-associated ER membrane (MAM) is a structure where these calcium-regulating organelles form close physical contact sites for efficient Ca2+ crosstalk. Despite the central importance of MAM Ca2+ dynamics in diverse biological processes, directly and specifically measuring Ca2+ concentrations inside MAM is technically challenging. Here, we develop MAM-Calflux, a MAM-specific BRET-based Ca2+ indicator. The successful application of the bimolecular fluorescence complementation (BiFC) concept highlights Ca2+-responsive BRET signals in MAM. The BiFC strategy imparts dual functionality as a Ca2+ indicator and quantitative structural marker specific for MAM. As a ratiometric Ca2+ indicator, MAM-Calflux estimates steady-state MAM Ca2+ levels. Finally, it enables the visualization of uneven intracellular distribution of MAM Ca2+ and the elucidation of abnormally accumulated MAM Ca2+ from the neurons of Parkinson's disease mouse model in both steady-state and stimulated conditions. Therefore, we propose that MAM-Calflux can be a versatile tool for ratiometrically measuring dynamic inter-organellar Ca2+ communication.
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Affiliation(s)
- Eunbyul Cho
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Youngsik Woo
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea.
| | - Yeongjun Suh
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Bo Kyoung Suh
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Soo Jeong Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Truong Thi My Nhung
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Jin Yeong Yoo
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Tran Diem Nghi
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Su Been Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Dong Jin Mun
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Sang Ki Park
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea.
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4
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Mitochondrial Ca2+ handling as a cell signaling hub: lessons from astrocyte function. Essays Biochem 2023; 67:63-75. [PMID: 36636961 DOI: 10.1042/ebc20220094] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 12/16/2022] [Accepted: 12/22/2022] [Indexed: 01/14/2023]
Abstract
Astrocytes are a heterogenous population of macroglial cells spread throughout the central nervous system with diverse functions, expression signatures, and intricate morphologies. Their subcellular compartments contain a distinct range of mitochondria, with functional microdomains exhibiting widespread activities, such as controlling local metabolism and Ca2+ signaling. Ca2+ is an ion of utmost importance, both physiologically and pathologically, and participates in critical central nervous system processes, including synaptic plasticity, neuron-astrocyte integration, excitotoxicity, and mitochondrial physiology and metabolism. The mitochondrial Ca2+ handling system is formed by the mitochondrial Ca2+ uniporter complex (MCUc), which mediates Ca2+ influx, and the mitochondrial Na+/Ca2+ exchanger (NCLX), responsible for most mitochondrial Ca2+ efflux, as well as additional components, including the mitochondrial permeability transition pore (mtPTP). Over the last decades, mitochondrial Ca2+ handling has been shown to be key for brain homeostasis, acting centrally in physiopathological processes such as astrogliosis, astrocyte-neuron activity integration, energy metabolism control, and neurodegeneration. In this review, we discuss the current state of knowledge regarding the mitochondrial Ca2+ handling system molecular composition, highlighting its impact on astrocytic homeostasis.
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5
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Lee JK, Rosales JL, Lee KY. Requirement for ER-mitochondria Ca 2+ transfer, ROS production and mPTP formation in L-asparaginase-induced apoptosis of acute lymphoblastic leukemia cells. Front Cell Dev Biol 2023; 11:1124164. [PMID: 36895789 PMCID: PMC9988955 DOI: 10.3389/fcell.2023.1124164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 02/13/2023] [Indexed: 02/23/2023] Open
Abstract
Acute lymphoblastic leukemia (aLL) is a malignant cancer in the blood and bone marrow characterized by rapid expansion of lymphoblasts. It is a common pediatric cancer and the principal basis of cancer death in children. Previously, we reported that L-asparaginase, a key component of acute lymphoblastic leukemia chemotherapy, causes IP3R-mediated ER Ca2+ release, which contributes to a fatal rise in [Ca2+]cyt, eliciting aLL cell apoptosis via upregulation of the Ca2+-regulated caspase pathway (Blood, 133, 2222-2232). However, the cellular events leading to the rise in [Ca2+]cyt following L-asparaginase-induced ER Ca2+ release remain obscure. Here, we show that in acute lymphoblastic leukemia cells, L-asparaginase causes mitochondrial permeability transition pore (mPTP) formation that is dependent on IP3R-mediated ER Ca2+ release. This is substantiated by the lack of L-asparaginase-induced ER Ca2+ release and loss of mitochondrial permeability transition pore formation in cells depleted of HAP1, a key component of the functional IP3R/HAP1/Htt ER Ca2+ channel. L-asparaginase induces ER Ca2+ transfer into mitochondria, which evokes an increase in reactive oxygen species (ROS) level. L-asparaginase-induced rise in mitochondrial Ca2+ and reactive oxygen species production cause mitochondrial permeability transition pore formation that then leads to an increase in [Ca2+]cyt. Such rise in [Ca2+]cyt is inhibited by Ruthenium red (RuR), an inhibitor of the mitochondrial calcium uniporter (MCU) that is required for mitochondrial Ca2+ uptake, and cyclosporine A (CsA), an mitochondrial permeability transition pore inhibitor. Blocking ER-mitochondria Ca2+ transfer, mitochondrial ROS production, and/or mitochondrial permeability transition pore formation inhibit L-asparaginase-induced apoptosis. Taken together, these findings fill in the gaps in our understanding of the Ca2+-mediated mechanisms behind L-asparaginase-induced apoptosis in acute lymphoblastic leukemia cells.
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Affiliation(s)
- Jung Kwon Lee
- Department of Cell Biology and Anatomy, Arnie Charbonneau Cancer and Alberta Children's Hospital Research Institutes, University of Calgary, Calgary, AB, Canada
| | - Jesusa L Rosales
- Department of Cell Biology and Anatomy, Arnie Charbonneau Cancer and Alberta Children's Hospital Research Institutes, University of Calgary, Calgary, AB, Canada
| | - Ki-Young Lee
- Department of Cell Biology and Anatomy, Arnie Charbonneau Cancer and Alberta Children's Hospital Research Institutes, University of Calgary, Calgary, AB, Canada
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Reggiani C, Marcucci L. A controversial issue: Can mitochondria modulate cytosolic calcium and contraction of skeletal muscle fibers? J Gen Physiol 2022; 154:213356. [PMID: 35849108 PMCID: PMC9297197 DOI: 10.1085/jgp.202213167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Mitochondria are characterized by a high capacity to accumulate calcium thanks to the electrochemical gradient created by the extrusion of protons in the respiratory chain. Thereby calcium can enter crossing the inner mitochondrial membrane via MCU complex, a high-capacity, low-affinity transport mechanism. Calcium uptake serves numerous purposes, among them the regulation of three dehydrogenases of the citric cycle, apoptosis via permeability transition, and, in some cell types, modulation of cytosolic calcium transients. This Review is focused on mitochondrial calcium uptake in skeletal muscle fibers and aims to reanalyze its functional impact. In particular, we ask whether mitochondrial calcium uptake is relevant for the control of cytosolic calcium transients and therefore of contractile performance. Recent data suggest that this may be the case, at least in particular conditions, as modified expression of MCU complex subunits or of proteins involved in mitochondrial dynamics and ablation of the main cytosolic calcium buffer, parvalbumin.
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Affiliation(s)
- Carlo Reggiani
- Department of Biomedical Sciences, University of Padova, Padova, Italy,Science and Research Center Koper, Institute for Kinesiology Research, Koper, Slovenia,Correspondence to Carlo Reggiani:
| | - Lorenzo Marcucci
- Department of Biomedical Sciences, University of Padova, Padova, Italy,Center for Biosystems Dynamics Research, RIKEN, Suita, Japan
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7
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Junge S, Schmieder F, Sasse P, Czarske J, Torres-Mapa ML, Heisterkamp A. Holographic optogenetic stimulation with calcium imaging as an all optical tool for cardiac electrophysiology. JOURNAL OF BIOPHOTONICS 2022; 15:e202100352. [PMID: 35397155 DOI: 10.1002/jbio.202100352] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/25/2022] [Accepted: 04/06/2022] [Indexed: 06/14/2023]
Abstract
All optical approaches to control and read out the electrical activity in a cardiac syncytium can improve our understanding of cardiac electrophysiology. Here, we demonstrate optogenetic stimulation of cardiomyocytes with high spatial precision using light foci generated with a ferroelectric spatial light modulator. Computer generated holograms binarized by bidirectional error diffusion create multiple foci with more even intensity distribution compared with thresholding approach. We evoke the electrical activity of cardiac HL1 cells expressing the channelrhodopsin-2 variant, ChR2(H134R) using single and multiple light foci and at the same time visualize the action potential using a calcium sensitive indicator called Cal-630. We show that localized regions in the cardiac monolayer can be stimulated enabling us to initiate signal propagation from a precise location. Furthermore, we demonstrate that probing the cardiac cells with multiple light foci enhances the excitability of the cardiac network. This approach opens new applications in manipulating and visualizing the electrical activity in a cardiac syncytium.
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Affiliation(s)
- Sebastian Junge
- Institute of Quantum Optics, Gottfried Wilhelm Leibniz University, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
| | - Felix Schmieder
- Faculty of Electrical and Computer Engineering, Laboratory of Measurement and Sensor System Technique and Competence Center Biomedical Computational Laser Systems (BIOLAS), TU Dresden, Dresden, Germany
| | - Philipp Sasse
- Medical Faculty, Institute of Physiology I, University of Bonn, Bonn, Germany
| | - Jürgen Czarske
- Faculty of Electrical and Computer Engineering, Laboratory of Measurement and Sensor System Technique and Competence Center Biomedical Computational Laser Systems (BIOLAS), TU Dresden, Dresden, Germany
- Faculty of Physics, School of Science and Excellence Cluster Physics of Life, TU Dresden, Dresden, Germany
| | - Maria Leilani Torres-Mapa
- Institute of Quantum Optics, Gottfried Wilhelm Leibniz University, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
| | - Alexander Heisterkamp
- Institute of Quantum Optics, Gottfried Wilhelm Leibniz University, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
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8
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Mitochondrial Ca 2+ Homeostasis: Emerging Roles and Clinical Significance in Cardiac Remodeling. Int J Mol Sci 2022; 23:ijms23063025. [PMID: 35328444 PMCID: PMC8954803 DOI: 10.3390/ijms23063025] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/01/2022] [Accepted: 03/03/2022] [Indexed: 01/27/2023] Open
Abstract
Mitochondria are the sites of oxidative metabolism in eukaryotes where the metabolites of sugars, fats, and amino acids are oxidized to harvest energy. Notably, mitochondria store Ca2+ and work in synergy with organelles such as the endoplasmic reticulum and extracellular matrix to control the dynamic balance of Ca2+ concentration in cells. Mitochondria are the vital organelles in heart tissue. Mitochondrial Ca2+ homeostasis is particularly important for maintaining the physiological and pathological mechanisms of the heart. Mitochondrial Ca2+ homeostasis plays a key role in the regulation of cardiac energy metabolism, mechanisms of death, oxygen free radical production, and autophagy. The imbalance of mitochondrial Ca2+ balance is closely associated with cardiac remodeling. The mitochondrial Ca2+ uniporter (mtCU) protein complex is responsible for the uptake and release of mitochondrial Ca2+ and regulation of Ca2+ homeostasis in mitochondria and consequently, in cells. This review summarizes the mechanisms of mitochondrial Ca2+ homeostasis in physiological and pathological cardiac remodeling and the regulatory effects of the mitochondrial calcium regulatory complex on cardiac energy metabolism, cell death, and autophagy, and also provides the theoretical basis for mitochondrial Ca2+ as a novel target for the treatment of cardiovascular diseases.
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9
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Ravasenga T, Ruben M, Regio V, Polenghi A, Petrini EM, Barberis A. Spatial regulation of coordinated excitatory and inhibitory synaptic plasticity at dendritic synapses. Cell Rep 2022; 38:110347. [PMID: 35139381 PMCID: PMC8844559 DOI: 10.1016/j.celrep.2022.110347] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 09/16/2021] [Accepted: 01/14/2022] [Indexed: 12/02/2022] Open
Abstract
The induction of synaptic plasticity at an individual dendritic glutamatergic spine can affect neighboring spines. This local modulation generates dendritic plasticity microdomains believed to expand the neuronal computational capacity. Here, we investigate whether local modulation of plasticity can also occur between glutamatergic synapses and adjacent GABAergic synapses. We find that the induction of long-term potentiation at an individual glutamatergic spine causes the depression of nearby GABAergic inhibitory synapses (within 3 μm), whereas more distant ones are potentiated. Notably, L-type calcium channels and calpain are required for this plasticity spreading. Overall, our data support a model whereby input-specific glutamatergic postsynaptic potentiation induces a spatially regulated rearrangement of inhibitory synaptic strength in the surrounding area through short-range heterosynaptic interactions. Such local coordination of excitatory and inhibitory synaptic plasticity is expected to influence dendritic information processing and integration. LTP of individual dendritic spines causes iLTD at neighboring GABAergic synapses Interaction between single-spine LTP and iLTD occurs in the spatial range of ±3 μm This iLTD depends on the local dendritic calcium increase and calpain activation iLTD is associated with reduced gephyrin clustering and increased GABAAR mobility
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Affiliation(s)
- Tiziana Ravasenga
- Neuroscience and Brain Technologies Department, Fondazione Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Massimo Ruben
- Neuroscience and Brain Technologies Department, Fondazione Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Vincenzo Regio
- Neuroscience and Brain Technologies Department, Fondazione Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Alice Polenghi
- Neuroscience and Brain Technologies Department, Fondazione Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Enrica Maria Petrini
- Neuroscience and Brain Technologies Department, Fondazione Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Andrea Barberis
- Neuroscience and Brain Technologies Department, Fondazione Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
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Acute RyR1 Ca 2+ leak enhances NADH-linked mitochondrial respiratory capacity. Nat Commun 2021; 12:7219. [PMID: 34893614 PMCID: PMC8664928 DOI: 10.1038/s41467-021-27422-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 11/18/2021] [Indexed: 12/25/2022] Open
Abstract
Sustained ryanodine receptor (RyR) Ca2+ leak is associated with pathological conditions such as heart failure or skeletal muscle weakness. We report that a single session of sprint interval training (SIT), but not of moderate intensity continuous training (MICT), triggers RyR1 protein oxidation and nitrosylation leading to calstabin1 dissociation in healthy human muscle and in in vitro SIT models (simulated SIT or S-SIT). This is accompanied by decreased sarcoplasmic reticulum Ca2+ content, increased levels of mitochondrial oxidative phosphorylation proteins, supercomplex formation and enhanced NADH-linked mitochondrial respiratory capacity. Mechanistically, (S-)SIT increases mitochondrial Ca2+ uptake in mouse myotubes and muscle fibres, and decreases pyruvate dehydrogenase phosphorylation in human muscle and mouse myotubes. Countering Ca2+ leak or preventing mitochondrial Ca2+ uptake blunts S-SIT-induced adaptations, a result supported by proteomic analyses. Here we show that triggering acute transient Ca2+ leak through RyR1 in healthy muscle may contribute to the multiple health promoting benefits of exercise.
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11
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Noble M, Lin QT, Sirko C, Houpt JA, Novello MJ, Stathopulos PB. Structural Mechanisms of Store-Operated and Mitochondrial Calcium Regulation: Initiation Points for Drug Discovery. Int J Mol Sci 2020; 21:E3642. [PMID: 32455637 PMCID: PMC7279490 DOI: 10.3390/ijms21103642] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 05/11/2020] [Accepted: 05/17/2020] [Indexed: 12/18/2022] Open
Abstract
Calcium (Ca2+) is a universal signaling ion that is essential for the life and death processes of all eukaryotes. In humans, numerous cell stimulation pathways lead to the mobilization of sarco/endoplasmic reticulum (S/ER) stored Ca2+, resulting in the propagation of Ca2+ signals through the activation of processes, such as store-operated Ca2+ entry (SOCE). SOCE provides a sustained Ca2+ entry into the cytosol; moreover, the uptake of SOCE-mediated Ca2+ by mitochondria can shape cytosolic Ca2+ signals, function as a feedback signal for the SOCE molecular machinery, and drive numerous mitochondrial processes, including adenosine triphosphate (ATP) production and distinct cell death pathways. In recent years, tremendous progress has been made in identifying the proteins mediating these signaling pathways and elucidating molecular structures, invaluable for understanding the underlying mechanisms of function. Nevertheless, there remains a disconnect between using this accumulating protein structural knowledge and the design of new research tools and therapies. In this review, we provide an overview of the Ca2+ signaling pathways that are involved in mediating S/ER stored Ca2+ release, SOCE, and mitochondrial Ca2+ uptake, as well as pinpoint multiple levels of crosstalk between these pathways. Further, we highlight the significant protein structures elucidated in recent years controlling these Ca2+ signaling pathways. Finally, we describe a simple strategy that aimed at applying the protein structural data to initiating drug design.
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Affiliation(s)
- Megan Noble
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Qi-Tong Lin
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Christian Sirko
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Jacob A. Houpt
- Department of Medicine, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada;
| | - Matthew J. Novello
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Peter B. Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
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12
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Gökerküçük EB, Tramier M, Bertolin G. Imaging Mitochondrial Functions: from Fluorescent Dyes to Genetically-Encoded Sensors. Genes (Basel) 2020; 11:genes11020125. [PMID: 31979408 PMCID: PMC7073610 DOI: 10.3390/genes11020125] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 12/18/2022] Open
Abstract
Mitochondria are multifunctional organelles that are crucial to cell homeostasis. They constitute the major site of energy production for the cell, they are key players in signalling pathways using secondary messengers such as calcium, and they are involved in cell death and redox balance paradigms. Mitochondria quickly adapt their dynamics and biogenesis rates to meet the varying energy demands of the cells, both in normal and in pathological conditions. Therefore, understanding simultaneous changes in mitochondrial functions is crucial in developing mitochondria-based therapy options for complex pathological conditions such as cancer, neurological disorders, and metabolic syndromes. To this end, fluorescence microscopy coupled to live imaging represents a promising strategy to track these changes in real time. In this review, we will first describe the commonly available tools to follow three key mitochondrial functions using fluorescence microscopy: Calcium signalling, mitochondrial dynamics, and mitophagy. Then, we will focus on how the development of genetically-encoded fluorescent sensors became a milestone for the understanding of these mitochondrial functions. In particular, we will show how these tools allowed researchers to address several biochemical activities in living cells, and with high spatiotemporal resolution. With the ultimate goal of tracking multiple mitochondrial functions simultaneously, we will conclude by presenting future perspectives for the development of novel genetically-encoded fluorescent biosensors.
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Abstract
Ionized calcium (Ca2+) is the most versatile cellular messenger. All cells use Ca2+ signals to regulate their activities in response to extrinsic and intrinsic stimuli. Alterations in cellular Ca2+ signaling and/or Ca2+ homeostasis can subvert physiological processes into driving pathological outcomes. Imaging of living cells over the past decades has demonstrated that Ca2+ signals encode information in their frequency, kinetics, amplitude, and spatial extent. These parameters alter depending on the type and intensity of stimulation, and cellular context. Moreover, it is evident that different cell types produce widely varying Ca2+ signals, with properties that suit their physiological functions. This primer discusses basic principles and mechanisms underlying cellular Ca2+ signaling and Ca2+ homeostasis. Consequently, we have cited some historical articles in addition to more recent findings. A brief summary of the core features of cellular Ca2+ signaling is provided, with particular focus on Ca2+ stores and Ca2+ transport across cellular membranes, as well as mechanisms by which Ca2+ signals activate downstream effector systems.
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14
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Deo C, Sheu SH, Seo J, Clapham DE, Lavis LD. Isomeric Tuning Yields Bright and Targetable Red Ca2+ Indicators. J Am Chem Soc 2019; 141:13734-13738. [DOI: 10.1021/jacs.9b06092] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Claire Deo
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, United States
| | - Shu-Hsien Sheu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, United States
| | - Jinyoung Seo
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, United States
| | - David E. Clapham
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, United States
| | - Luke D. Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, United States
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Fernandez-Sanz C, De la Fuente S, Sheu SS. Mitochondrial Ca 2+ concentrations in live cells: quantification methods and discrepancies. FEBS Lett 2019; 593:1528-1541. [PMID: 31058316 DOI: 10.1002/1873-3468.13427] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 04/29/2019] [Accepted: 05/02/2019] [Indexed: 12/11/2022]
Abstract
Intracellular Ca2+ signaling controls numerous cellular functions. Mitochondria respond to cytosolic Ca2+ changes by adapting mitochondrial functions and, in some cell types, shaping the spatiotemporal properties of the cytosolic Ca2+ signal. Numerous methods have been developed to specifically and quantitatively measure the mitochondrial-free Ca2+ concentrations ([Ca2+ ]m ), but there are still significant discrepancies in the calculated absolute values of [Ca2+ ]m in stimulated live cells. These discrepancies may be due to the distinct properties of the methods used to measure [Ca2+ ]m , the calcium-free/bound ratio, and the cell-type and stimulus-dependent Ca2+ dynamics. Critical processes happening in the mitochondria, such as ATP generation, ROS homeostasis, and mitochondrial permeability transition opening, depend directly on the [Ca2+ ]m values. Thus, precise determination of absolute [Ca2+ ]m values is imperative for understanding Ca2+ signaling. This review summarizes the reported calibrated [Ca2+ ]m values in many cell types and discusses the discrepancies among these values. Areas for future research are also proposed.
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Affiliation(s)
- Celia Fernandez-Sanz
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, PA, USA
| | - Sergio De la Fuente
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, PA, USA
| | - Shey-Shing Sheu
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, PA, USA
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16
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Li Y, Tran Q, Shrestha R, Piao L, Park S, Park J, Park J. LETM1 is required for mitochondrial homeostasis and cellular viability (Review). Mol Med Rep 2019; 19:3367-3375. [PMID: 30896806 PMCID: PMC6471456 DOI: 10.3892/mmr.2019.10041] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 03/12/2019] [Indexed: 12/13/2022] Open
Abstract
Leucine zipper/EF-hand-containing transmembrane protein 1 (LETM1) has been identified as the gene responsible for Wolf-Hirschhorn syndrome (WHS), which is characterized by intellectual disability, epilepsy, growth delay and craniofacial dysgenesis. LETM1 is a mitochondrial inner membrane protein that encodes a homolog of the yeast protein Mdm38, which is involved in mitochondrial morphology. In the present review, the importance of LETM1 in WHS and its role within the mitochondrion was explored. LETM1 governs the mitochondrion ion channel and is involved in mitochondrial respiration. Recent studies have reported that LETM1 acts as a mitochondrial Ca2+/H+ antiporter. LETM1 has also been identified as a K+/H+ exchanger, and serves a role in Mg2+ homeostasis. The function of LETM1 in mitochondria regulation is regulated by its binding partners, carboxyl-terminal modulator protein and mitochondrial ribosomal protein L36. Therefore, we describe the remarkable role of LETM1 in mitochondrial network physiology and its function in mitochondrion-mediated cell death. In the context of these findings, we suggest that the participation of LETM1 in tumorigenesis through the alteration of cancer metabolism should be investigated. This review provides a comprehensive description of LETM1 function, which is required for mitochondrial homeostasis and cellular viability.
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Affiliation(s)
- Yuwen Li
- Department of Pharmacology, Metabolic Syndrome and Cell Signaling Laboratory, Institute for Cancer Research, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea
| | - Quangdon Tran
- Department of Pharmacology, Metabolic Syndrome and Cell Signaling Laboratory, Institute for Cancer Research, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea
| | - Robin Shrestha
- Department of Pharmacology, Metabolic Syndrome and Cell Signaling Laboratory, Institute for Cancer Research, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea
| | - Longzhen Piao
- Department of Oncology, Affiliated Hospital of Yanbian University, Yanji, Jilin 133000, P.R. China
| | - Sungjin Park
- Department of Pharmacology, Metabolic Syndrome and Cell Signaling Laboratory, Institute for Cancer Research, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea
| | - Jisoo Park
- Department of Pharmacology, Metabolic Syndrome and Cell Signaling Laboratory, Institute for Cancer Research, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea
| | - Jongsun Park
- Department of Pharmacology, Metabolic Syndrome and Cell Signaling Laboratory, Institute for Cancer Research, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea
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17
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Courjaret R, Dib M, Machaca K. Spatially restricted subcellular Ca 2+ signaling downstream of store-operated calcium entry encoded by a cortical tunneling mechanism. Sci Rep 2018; 8:11214. [PMID: 30046136 PMCID: PMC6060099 DOI: 10.1038/s41598-018-29562-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 07/10/2018] [Indexed: 11/10/2022] Open
Abstract
Agonist-dependent Ca2+ mobilization results in Ca2+ store depletion and Store-Operated Calcium Entry (SOCE), which is spatially restricted to microdomains defined by cortical ER – plasma membrane contact sites (MCS). However, some Ca2+-dependent effectors that localize away from SOCE microdomains, are activated downstream of SOCE by mechanisms that remain obscure. One mechanism proposed initially in acinar cells and termed Ca2+ tunneling, mediates the uptake of Ca2+ flowing through SOCE into the ER followed by release at distal sites through IP3 receptors. Here we show that Ca2+ tunneling encodes exquisite specificity downstream of SOCE signal by dissecting the sensitivity and dependence of multiple effectors in HeLa cells. While mitochondria readily perceive Ca2+ release when stores are full, SOCE shows little effect in raising mitochondrial Ca2+, and Ca2+-tunneling is completely inefficient. In contrast, gKCa displays a similar sensitivity to Ca2+ release and tunneling, while the activation of NFAT1 is selectively responsive to SOCE and not to Ca2+ release. These results show that in contrast to the previously described long-range Ca2+ tunneling, in non-specialized HeLa cells this mechanism mediates spatially restricted Ca2+ rise within the cortical region of the cell to activate a specific subset of effectors.
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Affiliation(s)
- Raphael Courjaret
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City - Qatar Foundation, Doha, Qatar
| | - Maya Dib
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City - Qatar Foundation, Doha, Qatar
| | - Khaled Machaca
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City - Qatar Foundation, Doha, Qatar.
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18
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Drumm BT, Sung TS, Zheng H, Baker SA, Koh SD, Sanders KM. The effects of mitochondrial inhibitors on Ca 2+ signalling and electrical conductances required for pacemaking in interstitial cells of Cajal in the mouse small intestine. Cell Calcium 2018; 72:1-17. [PMID: 29748128 DOI: 10.1016/j.ceca.2018.01.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 01/26/2018] [Accepted: 01/27/2018] [Indexed: 01/16/2023]
Abstract
Interstitial cells of Cajal (ICC-MY) are pacemakers that generate and propagate electrical slow waves in gastrointestinal (GI) muscles. Slow waves appear to be generated by the release of Ca2+ from intracellular stores and activation of Ca2+-activated Cl- channels (Ano1). Conduction of slow waves to smooth muscle cells coordinates rhythmic contractions. Mitochondrial Ca2+ handling is currently thought to be critical for ICC pacemaking. Protonophores, inhibitors of the electron transport chain (FCCP, CCCP or antimycin) or mitochondrial Na+/Ca2+ exchange blockers inhibited slow waves in several GI muscles. Here we utilized Ca2+ imaging of ICC in small intestinal muscles in situ to determine the effects of mitochondrial drugs on Ca2+ transients in ICC. Muscles were obtained from mice expressing a genetically encoded Ca2+ indicator (GCaMP3) in ICC. FCCP, CCCP, antimycin, a uniporter blocker, Ru360, and a mitochondrial Na+/Ca2+ exchange inhibitor, CGP-37157 inhibited Ca2+ transients in ICC-MY. Effects were not due to depletion of ATP, as oligomycin did not affect Ca2+ transients. Patch-clamp experiments were performed to test the effects of the mitochondrial drugs on key pacemaker conductances, Ano1 and T-type Ca2+ (CaV3.2), in HEK293 cells. Antimycin blocked Ano1 and reduced CaV3.2 currents. CCCP blocked CaV3.2 current but did not affect Ano1 current. Ano1 and Cav3.2 currents were inhibited by CGP-37157. Inhibitory effects of mitochondrial drugs on slow waves and Ca2+ signalling in ICC can be explained by direct antagonism of key pacemaker conductances in ICC that generate and propagate slow waves. A direct obligatory role for mitochondria in pacemaker activity is therefore questionable.
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Affiliation(s)
- Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Tae S Sung
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Haifeng Zheng
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Sang D Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA.
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19
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Alevriadou BR, Shanmughapriya S, Patel A, Stathopulos PB, Madesh M. Mitochondrial Ca 2+ transport in the endothelium: regulation by ions, redox signalling and mechanical forces. J R Soc Interface 2017; 14:rsif.2017.0672. [PMID: 29237825 DOI: 10.1098/rsif.2017.0672] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 11/16/2017] [Indexed: 02/07/2023] Open
Abstract
Calcium (Ca2+) transport by mitochondria is an important component of the cell Ca2+ homeostasis machinery in metazoans. Ca2+ uptake by mitochondria is a major determinant of bioenergetics and cell fate. Mitochondrial Ca2+ uptake occurs via the mitochondrial Ca2+ uniporter (MCU) complex, an inner mitochondrial membrane protein assembly consisting of the MCU Ca2+ channel, as its core component, and the MCU complex regulatory/auxiliary proteins. In this review, we summarize the current knowledge on the molecular nature of the MCU complex and its regulation by intra- and extramitochondrial levels of divalent ions and reactive oxygen species (ROS). Intracellular Ca2+ concentration ([Ca2+]i), mitochondrial Ca2+ concentration ([Ca2+]m) and mitochondrial ROS (mROS) are intricately coupled in regulating MCU activity. Here, we highlight the contribution of MCU activity to vascular endothelial cell (EC) function. Besides the ionic and oxidant regulation, ECs are continuously exposed to haemodynamic forces (either pulsatile or oscillatory fluid mechanical shear stresses, depending on the precise EC location within the arteries). Thus, we also propose an EC mechanotransduction-mediated regulation of MCU activity in the context of vascular physiology and atherosclerotic vascular disease.
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Affiliation(s)
- B Rita Alevriadou
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH 43210, USA .,Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University, Columbus, OH 43210, USA.,Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Santhanam Shanmughapriya
- Department of Medical Genetics and Molecular Biochemistry, Temple University, Philadelphia, PA 19140, USA.,Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Akshar Patel
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH 43210, USA.,Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University, Columbus, OH 43210, USA.,Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada N6A 5C1
| | - Muniswamy Madesh
- Department of Medical Genetics and Molecular Biochemistry, Temple University, Philadelphia, PA 19140, USA .,Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
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20
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Yildirim V, Bertram R. Calcium Oscillation Frequency-Sensitive Gene Regulation and Homeostatic Compensation in Pancreatic β-Cells. Bull Math Biol 2017; 79:1295-1324. [PMID: 28497293 DOI: 10.1007/s11538-017-0286-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 04/27/2017] [Indexed: 02/03/2023]
Abstract
Pancreatic islet [Formula: see text]-cells are electrically excitable cells that secrete insulin in an oscillatory fashion when the blood glucose concentration is at a stimulatory level. Insulin oscillations are the result of cytosolic [Formula: see text] oscillations that accompany bursting electrical activity of [Formula: see text]-cells and are physiologically important. ATP-sensitive [Formula: see text] channels (K(ATP) channels) play the key role in setting the overall activity of the cell and in driving bursting, by coupling cell metabolism to the membrane potential. In humans, when there is a defect in K(ATP) channel function, [Formula: see text]-cells fail to respond appropriately to changes in the blood glucose level, and electrical and [Formula: see text] oscillations are lost. However, mice compensate for K(ATP) channel defects in islet [Formula: see text]-cells by employing alternative mechanisms to maintain electrical and [Formula: see text] oscillations. In a recent study, we showed that in mice islets in which K(ATP) channels are genetically knocked out another [Formula: see text] current, provided by inward-rectifying [Formula: see text] channels, is increased. With mathematical modeling, we demonstrated that a sufficient upregulation in these channels can account for the paradoxical electrical bursting and [Formula: see text] oscillations observed in these [Formula: see text]-cells. However, the question of determining the correct level of upregulation that is necessary for this compensation remained unanswered, and this question motivates the current study. [Formula: see text] is a well-known regulator of gene expression, and several examples have been shown of genes that are sensitive to the frequency of the [Formula: see text] signal. In this mathematical modeling study, we demonstrate that a [Formula: see text] oscillation frequency-sensitive gene transcription network can adjust the gene expression level of a compensating [Formula: see text] channel so as to rescue electrical bursting and [Formula: see text] oscillations in a model [Formula: see text]-cell in which the key K(ATP) current is removed. This is done without the prescription of a target [Formula: see text] level, but evolves naturally as a consequence of the feedback between the [Formula: see text]-dependent enzymes and the cell's electrical activity. More generally, the study indicates how [Formula: see text] can provide the link between gene expression and cellular electrical activity that promotes wild-type behavior in a cell following gene knockout.
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Affiliation(s)
- Vehpi Yildirim
- Department of Mathematics, Florida State University, Tallahassee, FL, 32306, USA
| | - Richard Bertram
- Department of Mathematics and Programs in Molecular Biophysics and Neuroscience, Florida State University, Tallahassee, FL, 32306, USA.
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21
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Matsuda S, Harada K, Ito M, Takizawa M, Wongso D, Tsuboi T, Kitaguchi T. Generation of a cGMP Indicator with an Expanded Dynamic Range by Optimization of Amino Acid Linkers between a Fluorescent Protein and PDE5α. ACS Sens 2017; 2:46-51. [PMID: 28722423 DOI: 10.1021/acssensors.6b00582] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Here we describe the development of a single fluorescent protein (FP)-based cGMP indicator, Green cGull, based on the cGMP binding domain from mouse phosphodiesterase 5α. The dynamic range of Green cGull was enhanced to a 7.5-fold fluorescence change upon cGMP binding by optimization of the amino acid linkers between the cGMP binding domain and FP. Green cGull has excitation and emission peaks at 498 and 522 nm, respectively, and specifically responds to cGMP in a dose-dependent manner. Live cell imaging analysis revealed that addition of a nitric oxide (NO) donor induced different cGMP kinetics and was cell-type dependent. We also found that the NO donor induced an increase of intracellular cGMP, while intracellular Ca2+ exhibited a complex profile, as revealed by dual-color imaging of cGMP and Ca2+. The results suggest that Green cGull sheds new light on understanding the complex interactions between various signaling molecules by multicolor imaging and that our systematic strategy for expanding the dynamic range of single-FP-based indicators is valuable to generate indicators for molecules of interest.
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Affiliation(s)
- Shogo Matsuda
- Department
of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan
| | - Kazuki Harada
- Department
of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
| | - Motoki Ito
- Department
of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan
| | - Mai Takizawa
- Department
of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
| | - Devina Wongso
- Cell
Signaling Group, Waseda Bioscience Research Institute in Singapore (WABIOS), 11 Biopolis Way #05-02 Helios, Singapore 138667, Singapore
| | - Takashi Tsuboi
- Department
of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan
- Department
of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
| | - Tetsuya Kitaguchi
- Cell
Signaling Group, Waseda Bioscience Research Institute in Singapore (WABIOS), 11 Biopolis Way #05-02 Helios, Singapore 138667, Singapore
- Comprehensive
Research Organization, Waseda University, #304, Block 120-4, 513 Wasedatsurumaki-cho, Shinjuku, Tokyo 162-0041, Japan
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22
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Spät A, Szanda G. The Role of Mitochondria in the Activation/Maintenance of SOCE: Store-Operated Ca 2+ Entry and Mitochondria. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 993:257-275. [PMID: 28900919 DOI: 10.1007/978-3-319-57732-6_14] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mitochondria extensively modify virtually all cellular Ca2+ transport processes, and store-operated Ca2+ entry (SOCE) is no exception to this rule. The interaction between SOCE and mitochondria is complex and reciprocal, substantially altering and, ultimately, fine-tuning both capacitative Ca2+ influx and mitochondrial function. Mitochondria, owing to their considerable Ca2+ accumulation ability, extensively buffer the cytosolic Ca2+ in their vicinity. In turn, the accumulated ion is released back into the neighboring cytosol during net Ca2+ efflux. Since store depletion itself and the successive SOCE are both Ca2+-regulated phenomena, mitochondrial Ca2+ handling may have wide-ranging effects on capacitative Ca2+ influx at any given time. In addition, mitochondria may also produce or consume soluble factors known to affect store-operated channels. On the other hand, Ca2+ entering the cell during SOCE is sensed by mitochondria, and the ensuing mitochondrial Ca2+ uptake boosts mitochondrial energy metabolism and, if Ca2+ overload occurs, may even lead to apoptosis or cell death. In several cell types, mitochondria seem to be sterically excluded from the confined space that forms between the plasma membrane (PM) and endoplasmic reticulum (ER) during SOCE. This implies that high-Ca2+ microdomains comparable to those observed between the ER and mitochondria do not form here. In the following chapter, the above aspects of the many-sided SOCE-mitochondrion interplay will be discussed in greater detail.
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Affiliation(s)
- András Spät
- Department of Physiology, Semmelweis University Medical School, POB 2, 1428, Budapest, Hungary.
- Laboratory of Molecular Physiology, Hungarian Academy of Sciences, Budapest, Hungary.
| | - Gergö Szanda
- Department of Physiology, Semmelweis University Medical School, POB 2, 1428, Budapest, Hungary
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23
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The m -AAA Protease Associated with Neurodegeneration Limits MCU Activity in Mitochondria. Mol Cell 2016; 64:148-162. [DOI: 10.1016/j.molcel.2016.08.020] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 06/16/2016] [Accepted: 08/12/2016] [Indexed: 11/23/2022]
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24
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Yun B, Lee H, Ewing H, Gelb MH, Leslie CC. Off-target effect of the cPLA2α inhibitor pyrrophenone: Inhibition of calcium release from the endoplasmic reticulum. Biochem Biophys Res Commun 2016; 479:61-6. [PMID: 27620490 DOI: 10.1016/j.bbrc.2016.09.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 09/07/2016] [Indexed: 01/10/2023]
Abstract
Cytosolic phospholipase A2α (cPLA2α) mediates agonist-induced release of arachidonic acid from membrane phospholipid for production of eicosanoids. The activation of cPLA2α involves increases in intracellular calcium, which binds to the C2 domain and promotes cPLA2α translocation from the cytosol to membrane to access substrate. The cell permeable pyrrolidine-containing cPLA2α inhibitors including pyrrophenone have been useful to understand cPLA2α function. Although this serine hydrolase inhibitor does not inhibit other PLA2s or downstream enzymes that metabolize arachidonic acid, we reported that it blocks increases in mitochondrial calcium and cell death in lung fibroblasts. In this study we used the calcium indicators G-CEPIA1er and CEPIA2mt to compare the effect of pyrrophenone in regulating calcium levels in the endoplasmic reticulum (ER) and mitochondria in response to A23187 and receptor stimulation. Pyrrophenone blocked calcium release from the ER and concomitant increases in mitochondrial calcium in response to stimulation by ATP, serum and A23187. In contrast, ER calcium release induced by the sarco/endoplasmic reticulum Ca(2+)-ATPase inhibitor thapsigargin was not blocked by pyrrophenone suggesting specificity for the calcium release pathway. As a consequence of blocking calcium mobilization, pyrrophenone inhibited serum-stimulated translocation of the cPLA2α C2 domain to Golgi. The ability of pyrrophenone to block ER calcium release is an off-target effect since it occurs in fibroblasts lacking cPLA2α. The results implicate a serine hydrolase in regulating ER calcium release and highlight the importance of careful dose-response studies with pyrrophenone to study cPLA2α function.
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Affiliation(s)
- Bogeon Yun
- Department of Pediatrics, National Jewish Health, 1400 Jackson St., Denver, CO 80206, USA
| | - HeeJung Lee
- Department of Pediatrics, National Jewish Health, 1400 Jackson St., Denver, CO 80206, USA
| | - Heather Ewing
- Departments of Chemistry and Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Michael H Gelb
- Departments of Chemistry and Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Christina C Leslie
- Department of Pediatrics, National Jewish Health, 1400 Jackson St., Denver, CO 80206, USA.
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25
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Suzuki J, Kanemaru K, Iino M. Genetically Encoded Fluorescent Indicators for Organellar Calcium Imaging. Biophys J 2016; 111:1119-1131. [PMID: 27477268 DOI: 10.1016/j.bpj.2016.04.054] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 03/30/2016] [Accepted: 04/01/2016] [Indexed: 12/14/2022] Open
Abstract
Optical Ca(2+) indicators are powerful tools for investigating intracellular Ca(2+) signals in living cells. Although a variety of Ca(2+) indicators have been developed, deciphering the physiological functions and spatiotemporal dynamics of Ca(2+) in intracellular organelles remains challenging. Genetically encoded Ca(2+) indicators (GECIs) using fluorescent proteins are promising tools for organellar Ca(2+) imaging, and much effort has been devoted to their development. In this review, we first discuss the key points of organellar Ca(2+) imaging and summarize the requirements for optimal organellar Ca(2+) indicators. Then, we highlight some of the recent advances in the engineering of fluorescent GECIs targeted to specific organelles. Finally, we discuss the limitations of currently available GECIs and the requirements for advancing the research on intraorganellar Ca(2+) signaling.
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Affiliation(s)
- Junji Suzuki
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; Department of Physiology, University of California San Francisco, San Francisco, California
| | - Kazunori Kanemaru
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Masamitsu Iino
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; Department of Cellular and Molecular Pharmacology, Nihon University School of Medicine, Tokyo, Japan.
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26
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Hirabayashi K, Hanaoka K, Egawa T, Kobayashi C, Takahashi S, Komatsu T, Ueno T, Terai T, Ikegaya Y, Nagano T, Urano Y. Development of practical red fluorescent probe for cytoplasmic calcium ions with greatly improved cell-membrane permeability. Cell Calcium 2016; 60:256-65. [PMID: 27349490 DOI: 10.1016/j.ceca.2016.06.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Revised: 06/04/2016] [Accepted: 06/07/2016] [Indexed: 01/26/2023]
Abstract
Fluorescence imaging of calcium ions (Ca(2+)) has become an essential technique for investigation of signaling pathways involving Ca(2+) as a second messenger. But, Ca(2+) signaling is involved in many biological phenomena, and therefore simultaneous visualization of Ca(2+) and other biomolecules (multicolor imaging) would be particularly informative. For this purpose, we set out to develop a fluorescent probe for Ca(2+) that would operate in a different color region (red) from that of probes for other molecules, many of which show green fluorescence, as exemplified by green fluorescent protein (GFP). We previously developed a red fluorescent probe for monitoring cytoplasmic Ca(2+) concentration, based on our established red fluorophore, TokyoMagenta (TM), but there remained room for improvement, especially as regards efficiency of introduction into cells. We considered that this issue was probably mainly due to limited water solubility of the probe. So, we designed and synthesized a red-fluorescent probe with improved water solubility. We confirmed that this Ca(2+) red-fluorescent probe showed high cell-membrane permeability with bright fluorescence. It was successfully applied to fluorescence imaging of not only live cells, but also brain slices, and should be practically useful for multicolor imaging studies of biological mechanisms.
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Affiliation(s)
- Kazuhisa Hirabayashi
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kenjiro Hanaoka
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
| | - Takahiro Egawa
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Chiaki Kobayashi
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Shodai Takahashi
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Toru Komatsu
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Tasuku Ueno
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takuya Terai
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yuji Ikegaya
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Tetsuo Nagano
- Drug Discovery Initiative, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yasuteru Urano
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; CREST, AMED, Saitama 332-0012, Japan.
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Paupe V, Prudent J, Dassa EP, Rendon OZ, Shoubridge EA. CCDC90A (MCUR1) is a cytochrome c oxidase assembly factor and not a regulator of the mitochondrial calcium uniporter. Cell Metab 2015; 21:109-16. [PMID: 25565209 DOI: 10.1016/j.cmet.2014.12.004] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 10/30/2014] [Accepted: 12/11/2014] [Indexed: 01/08/2023]
Abstract
Mitochondrial calcium is an important modulator of cellular metabolism. CCDC90A was reported to be a regulator of the mitochondrial calcium uniporter (MCU) complex, a selective channel that controls mitochondrial calcium uptake, and hence was renamed MCUR1. Here we show that suppression of CCDC90A in human fibroblasts produces a specific cytochrome c oxidase (COX) assembly defect, resulting in decreased mitochondrial membrane potential and reduced mitochondrial calcium uptake capacity. Fibroblasts from patients with COX assembly defects due to mutations in TACO1 or COX10 also showed reduced mitochondrial membrane potential and impaired calcium uptake capacity, both of which were rescued by expression of the respective wild-type cDNAs. Deletion of fmp32, a homolog of CCDC90A in Saccharomyces cerevisiae, an organism that lacks an MCU, also produces a COX deficiency, demonstrating that the function of CCDC90A is evolutionarily conserved. We conclude that CCDC90A plays a role in COX assembly and does not directly regulate MCU.
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Affiliation(s)
- Vincent Paupe
- Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada; Department of Human Genetics, McGill University, Montreal, QC H3A 2B4, Canada
| | - Julien Prudent
- Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada; Department of Neurology and Neurosurgery, McGill University, Montreal, QC H3A 2B4, Canada; Department of Biochemistry and Goodman Cancer Research Center, McGill University, Montreal, QC H3A 2B4, Canada
| | - Emmanuel P Dassa
- University of Paris-Sud, CNRS, UMR 8621, Institute of Genetics and Microbiology, Orsay, France
| | - Olga Zurita Rendon
- Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada; Department of Human Genetics, McGill University, Montreal, QC H3A 2B4, Canada
| | - Eric A Shoubridge
- Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada; Department of Human Genetics, McGill University, Montreal, QC H3A 2B4, Canada.
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Wolke C, Bukowska A, Goette A, Lendeckel U. Redox control of cardiac remodeling in atrial fibrillation. Biochim Biophys Acta Gen Subj 2014; 1850:1555-65. [PMID: 25513966 DOI: 10.1016/j.bbagen.2014.12.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 11/04/2014] [Accepted: 12/09/2014] [Indexed: 01/08/2023]
Abstract
BACKGROUND Atrial fibrillation (AF) is the most common arrhythmia in clinical practice and is a potential cause of thromboembolic events. AF induces significant changes in the electrophysiological properties of atrial myocytes and causes alterations in the structure, metabolism, and function of the atrial tissue. The molecular basis for the development of structural atrial remodeling of fibrillating human atria is still not fully understood. However, increased production of reactive oxygen or nitrogen species (ROS/RNS) and the activation of specific redox-sensitive signaling pathways observed both in patients with and animal models of AF are supposed to contribute to development, progression and self-perpetuation of AF. SCOPE OF REVIEW The present review summarizes the sources and targets of ROS/RNS in the setting of AF and focuses on key redox-sensitive signaling pathways that are implicated in the pathogenesis of AF and function either to aggravate or protect from disease. MAJOR CONCLUSIONS NADPH oxidases and various mitochondrial monooxygenases are major sources of ROS during AF. Besides direct oxidative modification of e.g. ion channels and ion handling proteins that are crucially involved in action potential generation and duration, AF leads to the reversible activation of redox-sensitive signaling pathways mediated by activation of redox-regulated proteins including Nrf2, NF-κB, and CaMKII. Both processes are recognized to contribute to the formation of a substrate for AF and, thus, to increase AF inducibility and duration. GENERAL SIGNIFICANCE AF is a prevalent disease and due to the current demographic developments its socio-economic relevance will further increase. Improving our understanding of the role that ROS and redox-related (patho)-mechanisms play in the development and progression of AF may allow the development of a targeted therapy for AF that surpasses the efficacy of previous general anti-oxidative strategies. This article is part of a Special Issue entitled Redox regulation of differentiation and de-differentiation.
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Affiliation(s)
- Carmen Wolke
- Institute of Medical Biochemistry and Molecular Biology, University Medicine Greifswald, D-17487 Greifswald, Germany
| | - Alicja Bukowska
- EUTRAF Working Group: Molecular Electrophysiology, University Hospital Magdeburg, D-39120 Magdeburg, Germany
| | - Andreas Goette
- EUTRAF Working Group: Molecular Electrophysiology, University Hospital Magdeburg, D-39120 Magdeburg, Germany; Department of Cardiology and Intensive Care Medicine, St. Vincenz-Hospital, D-33098 Paderborn, Germany
| | - Uwe Lendeckel
- Institute of Medical Biochemistry and Molecular Biology, University Medicine Greifswald, D-17487 Greifswald, Germany.
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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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Rimessi A, Bonora M, Marchi S, Patergnani S, Marobbio CMT, Lasorsa FM, Pinton P. Perturbed mitochondrial Ca2+signals as causes or consequences of mitophagy induction. Autophagy 2014; 9:1677-86. [DOI: 10.4161/auto.24795] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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Plasma membrane Ca2+-ATPase isoforms composition regulates cellular pH homeostasis in differentiating PC12 cells in a manner dependent on cytosolic Ca2+ elevations. PLoS One 2014; 9:e102352. [PMID: 25014339 PMCID: PMC4094512 DOI: 10.1371/journal.pone.0102352] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 06/17/2014] [Indexed: 12/14/2022] Open
Abstract
Plasma membrane Ca2+-ATPase (PMCA) by extruding Ca2+ outside the cell, actively participates in the regulation of intracellular Ca2+ concentration. Acting as Ca2+/H+ counter-transporter, PMCA transports large quantities of protons which may affect organellar pH homeostasis. PMCA exists in four isoforms (PMCA1-4) but only PMCA2 and PMCA3, due to their unique localization and features, perform more specialized function. Using differentiated PC12 cells we assessed the role of PMCA2 and PMCA3 in the regulation of intracellular pH in steady-state conditions and during Ca2+ overload evoked by 59 mM KCl. We observed that manipulation in PMCA expression elevated pHmito and pHcyto but only in PMCA2-downregulated cells higher mitochondrial pH gradient (ΔpH) was found in steady-state conditions. Our data also demonstrated that PMCA2 or PMCA3 knock-down delayed Ca2+ clearance and partially attenuated cellular acidification during KCl-stimulated Ca2+ influx. Because SERCA and NCX modulated cellular pH response in neglectable manner, and all conditions used to inhibit PMCA prevented KCl-induced pH drop, we considered PMCA2 and PMCA3 as mainly responsible for transport of protons to intracellular milieu. In steady-state conditions, higher TMRE uptake in PMCA2-knockdown line was driven by plasma membrane potential (Ψp). Nonetheless, mitochondrial membrane potential (Ψm) in this line was dissipated during Ca2+ overload. Cyclosporin and bongkrekic acid prevented Ψm loss suggesting the involvement of Ca2+-driven opening of mitochondrial permeability transition pore as putative underlying mechanism. The findings presented here demonstrate a crucial role of PMCA2 and PMCA3 in regulation of cellular pH and indicate PMCA membrane composition important for preservation of electrochemical gradient.
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Imaging intraorganellar Ca2+ at subcellular resolution using CEPIA. Nat Commun 2014; 5:4153. [PMID: 24923787 PMCID: PMC4082642 DOI: 10.1038/ncomms5153] [Citation(s) in RCA: 311] [Impact Index Per Article: 31.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 05/16/2014] [Indexed: 12/19/2022] Open
Abstract
The endoplasmic reticulum (ER) and mitochondria accumulate Ca2+ within their lumens to regulate numerous cell functions. However, determining the dynamics of intraorganellar Ca2+ has proven to be difficult. Here we describe a family of genetically encoded Ca2+ indicators, named calcium-measuring organelle-entrapped protein indicators (CEPIA), which can be utilized for intraorganellar Ca2+ imaging. CEPIA, which emit green, red or blue/green fluorescence, are engineered to bind Ca2+ at intraorganellar Ca2+ concentrations. They can be targeted to different organelles and may be used alongside other fluorescent molecular markers, expanding the range of cell functions that can be simultaneously analysed. The spatiotemporal resolution of CEPIA makes it possible to resolve Ca2+ import into individual mitochondria while simultaneously measuring ER and cytosolic Ca2+. We have used these imaging capabilities to reveal differential Ca2+ handling in individual mitochondria. CEPIA imaging is a useful new tool to further the understanding of organellar functions. The use of intracellular calcium sensors provides important information about the dynamics of calcium signalling in cells. Here Suzuki et al. develop organelle-targeted sensors to simultaneously measure calcium concentrations in ER and mitochondria, and uncover novel insights into calcium flux in mitochondria.
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Mitochondrial matrix Ca²⁺ accumulation regulates cytosolic NAD⁺/NADH metabolism, protein acetylation, and sirtuin expression. Mol Cell Biol 2014; 34:2890-902. [PMID: 24865966 DOI: 10.1128/mcb.00068-14] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mitochondrial calcium uptake stimulates bioenergetics and drives energy production in metabolic tissue. It is unknown how a calcium-mediated acceleration in matrix bioenergetics would influence cellular metabolism in glycolytic cells that do not require mitochondria for ATP production. Using primary human endothelial cells (ECs), we discovered that repetitive cytosolic calcium signals (oscillations) chronically loaded into the mitochondrial matrix. Mitochondrial calcium loading in turn stimulated bioenergetics and a persistent elevation in NADH. Rather than serving as an impetus for mitochondrial ATP generation, matrix NADH rapidly transmitted to the cytosol to influence the activity and expression of cytosolic sirtuins, resulting in global changes in protein acetylation. In endothelial cells, the mitochondrion-driven reduction in both the cytosolic and mitochondrial NAD(+)/NADH ratio stimulated a compensatory increase in SIRT1 protein levels that had an anti-inflammatory effect. Our studies reveal the physiologic importance of mitochondrial bioenergetics in the metabolic regulation of sirtuins and cytosolic signaling cascades.
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Deak AT, Blass S, Khan MJ, Groschner LN, Waldeck-Weiermair M, Hallström S, Graier WF, Malli R. IP3-mediated STIM1 oligomerization requires intact mitochondrial Ca2+ uptake. J Cell Sci 2014; 127:2944-55. [PMID: 24806964 PMCID: PMC4077590 DOI: 10.1242/jcs.149807] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mitochondria contribute to cell signaling by controlling store-operated Ca2+ entry (SOCE). SOCE is activated by Ca2+ release from the endoplasmic reticulum (ER), whereupon stromal interacting molecule 1 (STIM1) forms oligomers, redistributes to ER–plasma-membrane junctions and opens plasma membrane Ca2+ channels. The mechanisms by which mitochondria interfere with the complex process of SOCE are insufficiently clarified. In this study, we used an shRNA approach to investigate the direct involvement of mitochondrial Ca2+ buffering in SOCE. We demonstrate that knockdown of either of two proteins that are essential for mitochondrial Ca2+ uptake, the mitochondrial calcium uniporter (MCU) or uncoupling protein 2 (UCP2), results in decelerated STIM1 oligomerization and impaired SOCE following cell stimulation with an inositol-1,4,5-trisphosphate (IP3)-generating agonist. Upon artificially augmented cytosolic Ca2+ buffering or ER Ca2+ depletion by sarcoplasmic or endoplasmic reticulum Ca2+-ATPase (SERCA) inhibitors, STIM1 oligomerization did not rely on intact mitochondrial Ca2+ uptake. However, MCU-dependent mitochondrial sequestration of Ca2+ entering through the SOCE pathway was essential to prevent slow deactivation of SOCE. Our findings show a stimulus-specific contribution of mitochondrial Ca2+ uptake to the SOCE machinery, likely through a role in shaping cytosolic Ca2+ micro-domains.
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Affiliation(s)
- Andras T Deak
- The Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010-Graz, Austria
| | - Sandra Blass
- The Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010-Graz, Austria
| | - Muhammad J Khan
- The Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010-Graz, Austria
| | - Lukas N Groschner
- The Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010-Graz, Austria
| | - Markus Waldeck-Weiermair
- The Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010-Graz, Austria
| | - Seth Hallström
- The Institute of Physiological Chemistry, Center of Physiological Medicine, Medical University of Graz, 8010-Graz, Austria
| | - Wolfgang F Graier
- The Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010-Graz, Austria
| | - Roland Malli
- The Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010-Graz, Austria
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De Bock M, Decrock E, Wang N, Bol M, Vinken M, Bultynck G, Leybaert L. The dual face of connexin-based astroglial Ca(2+) communication: a key player in brain physiology and a prime target in pathology. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2211-32. [PMID: 24768716 DOI: 10.1016/j.bbamcr.2014.04.016] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/11/2014] [Accepted: 04/12/2014] [Indexed: 12/21/2022]
Abstract
For decades, studies have been focusing on the neuronal abnormalities that accompany neurodegenerative disorders. Yet, glial cells are emerging as important players in numerous neurological diseases. Astrocytes, the main type of glia in the central nervous system , form extensive networks that physically and functionally connect neuronal synapses with cerebral blood vessels. Normal brain functioning strictly depends on highly specialized cellular cross-talk between these different partners to which Ca(2+), as a signaling ion, largely contributes. Altered intracellular Ca(2+) levels are associated with neurodegenerative disorders and play a crucial role in the glial responses to injury. Intracellular Ca(2+) increases in single astrocytes can be propagated toward neighboring cells as intercellular Ca(2+) waves, thereby recruiting a larger group of cells. Intercellular Ca(2+) wave propagation depends on two, parallel, connexin (Cx) channel-based mechanisms: i) the diffusion of inositol 1,4,5-trisphosphate through gap junction channels that directly connect the cytoplasm of neighboring cells, and ii) the release of paracrine messengers such as glutamate and ATP through hemichannels ('half of a gap junction channel'). This review gives an overview of the current knowledge on Cx-mediated Ca(2+) communication among astrocytes as well as between astrocytes and other brain cell types in physiology and pathology, with a focus on the processes of neurodegeneration and reactive gliosis. Research on Cx-mediated astroglial Ca(2+) communication may ultimately shed light on the development of targeted therapies for neurodegenerative disorders in which astrocytes participate. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.
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Affiliation(s)
- Marijke De Bock
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Elke Decrock
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium.
| | - Nan Wang
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Mélissa Bol
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Mathieu Vinken
- Department of Toxicology, Center for Pharmaceutical Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, B-1090 Brussels, Belgium
| | - Geert Bultynck
- Department of Cellular and Molecular Medicine, Laboratory of Molecular and Cellular Signalling, KULeuven, Campus Gasthuisberg O/N-I bus 802, B-3000 Leuven, Belgium
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
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Pierro C, Cook SJ, Foets TCF, Bootman MD, Roderick HL. Oncogenic K-Ras suppresses IP₃-dependent Ca²⁺ release through remodelling of the isoform composition of IP₃Rs and ER luminal Ca²⁺ levels in colorectal cancer cell lines. J Cell Sci 2014; 127:1607-19. [PMID: 24522186 DOI: 10.1242/jcs.141408] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The GTPase Ras is a molecular switch engaged downstream of G-protein-coupled receptors and receptor tyrosine kinases that controls multiple cell-fate-determining signalling pathways. Ras signalling is frequently deregulated in cancer, underlying associated changes in cell phenotype. Although Ca(2+) signalling pathways control some overlapping functions with Ras, and altered Ca(2+) signalling pathways are emerging as important players in oncogenic transformation, how Ca(2+) signalling is remodelled during transformation and whether it has a causal role remains unclear. We have investigated Ca(2+) signalling in two human colorectal cancer cell lines and their isogenic derivatives in which the allele encoding oncogenic K-Ras (G13D) was deleted by homologous recombination. We show that agonist-induced Ca(2+) release from the endoplasmic reticulum (ER) intracellular Ca(2+) stores is enhanced by loss of K-Ras(G13D) through an increase in the Ca(2+) content of the ER store and a modification of the abundance of inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) subtypes. Consistently, uptake of Ca(2+) into mitochondria and sensitivity to apoptosis was enhanced as a result of K-Ras(G13D) loss. These results suggest that suppression of Ca(2+) signalling is a common response to naturally occurring levels of K-Ras(G13D), and that this contributes to a survival advantage during oncogenic transformation.
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Affiliation(s)
- Cristina Pierro
- Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT UK
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38
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Webster KA. Mitochondrial membrane permeabilization and cell death during myocardial infarction: roles of calcium and reactive oxygen species. Future Cardiol 2013; 8:863-84. [PMID: 23176689 DOI: 10.2217/fca.12.58] [Citation(s) in RCA: 223] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Excess generation of reactive oxygen species (ROS) and cytosolic calcium accumulation play major roles in the initiation of programmed cell death during acute myocardial infarction. Cell death may include necrosis, apoptosis and autophagy, and combinations thereof. During ischemia, calcium handling between the sarcoplasmic reticulum and myofilament is disrupted and calcium is diverted to the mitochondria causing swelling. Reperfusion, while essential for survival, reactivates energy transduction and contractility and causes the release of ROS and additional ionic imbalance. During acute ischemia-reperfusion, the principal death pathways are programmed necrosis and apoptosis through the intrinsic pathway, initiated by the opening of the mitochondrial permeability transition pore and outer mitochondrial membrane permeabilization, respectively. Despite intense investigation, the mechanisms of action and modes of regulation of mitochondrial membrane permeabilization are incompletely understood. Extrinsic apoptosis, necroptosis and autophagy may also contribute to ischemia-reperfusion injury. In this review, the roles of dysregulated calcium and ROS and the contributions of Bcl-2 proteins, as well as mitochondrial morphology in promoting mitochondrial membrane permeability change and the ensuing cell death during myocardial infarction are discussed.
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Affiliation(s)
- Keith A Webster
- Department of Molecular & Cellular Pharmacology, University of Miami Medical Center, FL 33101, USA.
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39
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Egawa T, Hirabayashi K, Koide Y, Kobayashi C, Takahashi N, Mineno T, Terai T, Ueno T, Komatsu T, Ikegaya Y, Matsuki N, Nagano T, Hanaoka K. Red Fluorescent Probe for Monitoring the Dynamics of Cytoplasmic Calcium Ions. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201210279] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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40
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Egawa T, Hirabayashi K, Koide Y, Kobayashi C, Takahashi N, Mineno T, Terai T, Ueno T, Komatsu T, Ikegaya Y, Matsuki N, Nagano T, Hanaoka K. Red Fluorescent Probe for Monitoring the Dynamics of Cytoplasmic Calcium Ions. Angew Chem Int Ed Engl 2013; 52:3874-7. [DOI: 10.1002/anie.201210279] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2012] [Revised: 01/26/2013] [Indexed: 01/20/2023]
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41
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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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42
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Takekawa M, Furuno T, Hirashima N, Nakanishi M. Mitochondria take up Ca2+ in two steps dependently on store-operated Ca2+ entry in mast cells. Biol Pharm Bull 2012; 35:1354-60. [PMID: 22863937 DOI: 10.1248/bpb.b110576] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ability of mitochondria to take up Ca2+ has important functional implications for modulation of cellular Ca2+ signaling. Mitochondrial Ca2+ uptake is stimulated by an increase in cytosolic Ca2+ concentration ([Ca2+]c). Here, we found that the increase in mitochondrial Ca2+ concentration ([Ca2+]m) occurs in two steps in a single antigen-activated mast cell in the presence of extracellular Ca2+ (1.0 mM). The two-step elevation of [Ca2+]m was also observed after adding thapsigargin, an inhibitor of sarcoplasmic/endoplasmic reticulum Ca2+-ATPase. The proportion of mitochondria showing the two-step Ca2+ elevation dropped off in direct accord with decrease in extracellular Ca2+ concentration. The second step of the [Ca2+]m increase was suppressed significantly in the absence of extracellular Ca2+ and in knockdown cells of stromal interaction molecule 1 (STIM1), an essential molecule on endoplasmic reticulum (ER) membrane for store-operated Ca2+ entry, in the presence of extracellular Ca2+ (1.0 mM), while the first elevation was not affected in either case. The results indicate that mitochondria take up cytosolic Ca2+ in two steps; first and second uptakes are derived from the Ca2+ release from ER and the Ca2+ influx through store-operated Ca2+ channels, respectively. Additionally, rotenone and antimycin A, which are inhibitors of mitochondrial electron transport complex I and III, respectively, diminished mitochondrial Ca2+ uptake and significantly suppressed degranulation stimulated with antigen. The mitochondrial Ca2+ uptake may modulate mast cell function by regulating the [Ca2+]c.
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Affiliation(s)
- Marie Takekawa
- School of Pharmacy, Aichi Gakuin University, Nagoya, Japan
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43
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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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Peppiatt-Wildman CM, Crawford C, Hall AM. Fluorescence imaging of intracellular calcium signals in intact kidney tissue. Nephron Clin Pract 2012; 121:e49-58. [PMID: 23147410 DOI: 10.1159/000342812] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 08/14/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Intracellular calcium (Ca(2+)) plays an important role in normal renal physiology and in the pathogenesis of various kidney diseases; however, the study of Ca(2+) signals in intact tissue has been limited by technical difficulties, including achieving adequate loading of Ca(2+)-sensitive fluorescent dyes. The kidney slice preparation represents a model whereby three-dimensional tissue architecture is preserved and structures in both the cortex and medulla can be imaged using confocal or multiphoton microscopy. METHODS Ca(2+)-sensitive dyes Rhod-2, Fura-red and Fluo-4 were loaded into tubular and vascular cells in rat kidney slices using a re-circulating perfusion system and real-time imaging of Ca(2+) signals was recorded by confocal microscopy. Kidney slices were also obtained from transgenic mice expressing the GCaMP2 Ca(2+)-sensor in their endothelial cells and real time Ca(2+) transients stimulated by physiological stimuli. RESULTS Wide spread loading of Ca(2+) indicators was achieved in the tubular and vascular structures of both the medulla and cortex. Real time Ca(2+) signals were successfully recorded in different intracellular compartments of both rat and mouse cortical and medullary tubules in response to physiological stimuli (ATP and angiotensin II). Glomerular Ca(2+) transients were similarly recorded in kidney slices taken from the transgenic mouse expressing the GCaMP2 Ca(2+)-sensor. CONCLUSION We present new approaches that can be adopted to image cytosolic and mitochondrial Ca(2+) signals within various cell types in intact kidney tissue. Moreover, techniques described in this study can be used to facilitate future detailed investigations of intracellular Ca(2+) homeostasis in renal health and disease.
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Affiliation(s)
- C M Peppiatt-Wildman
- Medway School of Pharmacy, The Universities of Kent and Greenwich at Medway, Chatham Maritime, UK. C.M.Peppiatt @ kent.ac.uk
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Waldeck-Weiermair M, Alam MR, Khan MJ, Deak AT, Vishnu N, Karsten F, Imamura H, Graier WF, Malli R. Spatiotemporal correlations between cytosolic and mitochondrial Ca(2+) signals using a novel red-shifted mitochondrial targeted cameleon. PLoS One 2012; 7:e45917. [PMID: 23029314 PMCID: PMC3448721 DOI: 10.1371/journal.pone.0045917] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 08/23/2012] [Indexed: 01/11/2023] Open
Abstract
The transfer of Ca2+ from the cytosol into the lumen of mitochondria is a crucial process that impacts cell signaling in multiple ways. Cytosolic Ca2+ ([Ca2+]cyto) can be excellently quantified with the ratiometric Ca2+ probe fura-2, while genetically encoded Förster resonance energy transfer (FRET)-based fluorescent Ca2+ sensors, the cameleons, are efficiently used to specifically measure Ca2+ within organelles. However, because of a significant overlap of the fura-2 emission with the spectra of the cyan and yellow fluorescent protein of most of the existing cameleons, the measurement of fura-2 and cameleons within one given cell is a complex task. In this study, we introduce a novel approach to simultaneously assess [Ca2+]cyto and mitochondrial Ca2+ ([Ca2+]mito) signals at the single cell level. In order to eliminate the spectral overlap we developed a novel red-shifted cameleon, D1GO-Cam, in which the green and orange fluorescent proteins were used as the FRET pair. This ratiometric Ca2+ probe could be successfully targeted to mitochondria and was suitable to be used simultaneously with fura-2 to correlate [Ca2+]cyto and [Ca2+]mito within same individual cells. Our data indicate that depending on the kinetics of [Ca2+]cyto rises there is a significant lag between onset of [Ca2+]cyto and [Ca2+]mito signals, pointing to a certain threshold of [Ca2+]cyto necessary to activate mitochondrial Ca2+ uptake. The temporal correlation between [Ca2+]mito and [Ca2+]cyto as well as the efficiency of the transfer of Ca2+ from the cytosol into mitochondria varies between different cell types. Moreover, slow mitochondrial Ca2+ extrusion and a desensitization of mitochondrial Ca2+ uptake cause a clear difference in patterns of mitochondrial and cytosolic Ca2+ oscillations of pancreatic beta-cells in response to D-glucose.
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Affiliation(s)
- Markus Waldeck-Weiermair
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
| | - Muhammad Rizwan Alam
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
| | - Muhammad Jadoon Khan
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
| | - Andras T. Deak
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
| | - Neelanjan Vishnu
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
| | - Felix Karsten
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
| | - Hiromi Imamura
- Precursory Research for Embryonic Science, Japan Science and Technology Agency, Tokyo, Japan
| | - Wolfgang F. Graier
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
| | - Roland Malli
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
- * E-mail:
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Abstract
Mitochondria may function as multiple separate organelles or as a single electrically coupled continuum to modulate changes in [Ca2+]c (cytoplasmic Ca2+ concentration) in various cell types. Mitochondria may also be tethered to the internal Ca2+ store or plasma membrane in particular parts of cells to facilitate the organelles modulation of local and global [Ca2+]c increases. Differences in the organization and positioning contributes significantly to the at times apparently contradictory reports on the way mitochondria modulate [Ca2+]c signals. In the present paper, we review the organization of mitochondria and the organelles role in Ca2+ signalling.
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Sun J, Zhang CL, Deng SR, Lu CF, Shen X, Zhou XY, Zheng XJ, Hu ZM, Chen SL. An ATP signalling pathway in plant cells: extracellular ATP triggers programmed cell death in Populus euphratica. PLANT, CELL & ENVIRONMENT 2012; 35:893-916. [PMID: 22070751 DOI: 10.1111/j.1365-3040.2011.02461.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We elucidated the extracellular ATP (eATP) signalling cascade active in programmed cell death (PCD) using cell cultures of Populus euphratica. Millimolar amounts of eATP induced a dose- and time-dependent reduction in viability, and the agonist-treated cells displayed hallmark features of PCD. eATP caused an elevation of cytosolic Ca(2+) levels, resulting in Ca(2+) uptake by the mitochondria and subsequent H(2) O(2) accumulation. P. euphratica exhibited an increased mitochondrial transmembrane potential, and cytochrome c was released without opening of the permeability transition pore over the period of ATP stimulation. Moreover, the eATP-induced increase of intracellular ATP, essential for the activation of caspase-like proteases and subsequent PCD, was found to be related to increased mitochondrial transmembrane potential. NO is implicated as a downstream component of the cytosolic Ca(2+) concentration but plays a negligible role in eATP-stimulated cell death. We speculate that ATP binds purinoceptors in the plasma membrane, leading to the induction of downstream intermediate signals, as the proposed sequence of events in PCD signalling was terminated by the animal P2 receptor antagonist suramin.
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Affiliation(s)
- Jian Sun
- National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University (Box 162), Beijing 100083 College of Life Science, Xuzhou Normal University, Xuzhou 221116, Jiangsu, China
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Abstract
Since 1929, when it was discovered that ATP is a substrate for muscle contraction, the knowledge about this purine nucleotide has been greatly expanded. Many aspects of cell metabolism revolve around ATP production and consumption. It is important to understand the concepts of glucose and oxygen consumption in aerobic and anaerobic life and to link bioenergetics with the vast amount of reactions occurring within cells. ATP is universally seen as the energy exchange factor that connects anabolism and catabolism but also fuels processes such as motile contraction, phosphorylations, and active transport. It is also a signalling molecule in the purinergic signalling mechanisms. In this review, we will discuss all the main mechanisms of ATP production linked to ADP phosphorylation as well the regulation of these mechanisms during stress conditions and in connection with calcium signalling events. Recent advances regarding ATP storage and its special significance for purinergic signalling will also be reviewed.
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49
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Spät A, Szanda G. Special features of mitochondrial Ca²⁺ signalling in adrenal glomerulosa cells. Pflugers Arch 2012; 464:43-50. [PMID: 22395411 DOI: 10.1007/s00424-012-1086-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 02/10/2012] [Accepted: 02/14/2012] [Indexed: 11/30/2022]
Abstract
Aldosterone, secreted by adrenal glomerulosa cells, allows the adaptation of the vertebrate organism to a wide range of physiological and pathological stimuli including acute haemodynamic challenges and long-term changes in dietary sodium and potassium intake. Most of the extracellular signals are mediated by cytosolic Ca²⁺ signal deriving from Ca²⁺ release, store-operated and/or voltage-gated Ca²⁺ influx. Mitochondria in glomerulosa cells play a fundamental role in generating and modulating the final biological response. These organelles not only house several enzymes of aldosterone biosynthesis but also-in a Ca²⁺-dependent manner-provide NADPH for the function of these enzymes. Moreover, mitochondria, constituting a high portion of cytoplasmic volume and displaying a uniquely low-threshold Ca²⁺ sequestering ability, shape and thus modulate the decoding of the complex cytosolic Ca²⁺ response. The unusual features of mitochondrial Ca²⁺ signalling that permit such an integrative function in adrenal glomerulosa cells are hereby described.
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Affiliation(s)
- András Spät
- Department of Physiology, Semmelweis University, Budapest, Hungary.
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Plattner H, Sehring IM, Mohamed IK, Miranda K, De Souza W, Billington R, Genazzani A, Ladenburger EM. Calcium signaling in closely related protozoan groups (Alveolata): non-parasitic ciliates (Paramecium, Tetrahymena) vs. parasitic Apicomplexa (Plasmodium, Toxoplasma). Cell Calcium 2012; 51:351-82. [PMID: 22387010 DOI: 10.1016/j.ceca.2012.01.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 01/10/2012] [Accepted: 01/12/2012] [Indexed: 12/20/2022]
Abstract
The importance of Ca2+-signaling for many subcellular processes is well established in higher eukaryotes, whereas information about protozoa is restricted. Recent genome analyses have stimulated such work also with Alveolates, such as ciliates (Paramecium, Tetrahymena) and their pathogenic close relatives, the Apicomplexa (Plasmodium, Toxoplasma). Here we compare Ca2+ signaling in the two closely related groups. Acidic Ca2+ stores have been characterized in detail in Apicomplexa, but hardly in ciliates. Two-pore channels engaged in Ca2+-release from acidic stores in higher eukaryotes have not been stingently characterized in either group. Both groups are endowed with plasma membrane- and endoplasmic reticulum-type Ca2+-ATPases (PMCA, SERCA), respectively. Only recently was it possible to identify in Paramecium a number of homologs of ryanodine and inositol 1,3,4-trisphosphate receptors (RyR, IP3R) and to localize them to widely different organelles participating in vesicle trafficking. For Apicomplexa, physiological experiments suggest the presence of related channels although their identity remains elusive. In Paramecium, IP3Rs are constitutively active in the contractile vacuole complex; RyR-related channels in alveolar sacs are activated during exocytosis stimulation, whereas in the parasites the homologous structure (inner membrane complex) may no longer function as a Ca2+ store. Scrutinized comparison of the two closely related protozoan phyla may stimulate further work and elucidate adaptation to parasitic life. See also "Conclusions" section.
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Affiliation(s)
- H Plattner
- Department of Biology, University of Konstanz, P.O. Box 5560, 78457 Konstanz, Germany.
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