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Roman B, Mastoor Y, Sun J, Villanueva HC, Hinojosa G, Springer D, Liu JC, Murphy E. MICU3 Regulates Mitochondrial Calcium and Cardiac Hypertrophy. Circ Res 2024; 135:26-40. [PMID: 38747181 PMCID: PMC11189743 DOI: 10.1161/circresaha.123.324026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 05/01/2024] [Indexed: 06/22/2024]
Abstract
BACKGROUND Calcium (Ca2+) uptake by mitochondria occurs via the mitochondrial Ca2+ uniporter. Mitochondrial Ca2+ uniporter exists as a complex, regulated by 3 MICU (mitochondrial Ca2+ uptake) proteins localized in the intermembrane space: MICU1, MICU2, and MICU3. Although MICU3 is present in the heart, its role is largely unknown. METHODS We used CRISPR-Cas9 to generate a mouse with global deletion of MICU3 and an adeno-associated virus (AAV9) to overexpress MICU3 in wild-type mice. We examined the role of MICU3 in regulating mitochondrial calcium ([Ca2+]m) in ex vivo hearts using an optical method following adrenergic stimulation in perfused hearts loaded with a Ca2+-sensitive fluorophore. Additionally, we studied how deletion and overexpression of MICU3, respectively, impact cardiac function in vivo by echocardiography and the molecular composition of the mitochondrial Ca2+ uniporter complex via Western blot, immunoprecipitation, and Blue native-PAGE analysis. Finally, we measured MICU3 expression in failing human hearts. RESULTS MICU3 knock out hearts and cardiomyocytes exhibited a significantly smaller increase in [Ca2+]m than wild-type hearts following acute isoproterenol infusion. In contrast, heart with overexpression of MICU3 exhibited an enhanced increase in [Ca2+]m compared with control hearts. Echocardiography analysis showed no significant difference in cardiac function in knock out MICU3 mice relative to wild-type mice at baseline. However, mice with overexpression of MICU3 exhibited significantly reduced ejection fraction and fractional shortening compared with control mice. We observed a significant increase in the ratio of heart weight to tibia length in hearts with overexpression of MICU3 compared with controls, consistent with hypertrophy. We also found a significant decrease in MICU3 protein and expression in failing human hearts. CONCLUSIONS Our results indicate that increased and decreased expression of MICU3 enhances and reduces, respectively, the uptake of [Ca2+]m in the heart. We conclude that MICU3 plays an important role in regulating [Ca2+]m physiologically, and overexpression of MICU3 is sufficient to induce cardiac hypertrophy, making MICU3 a possible therapeutic target.
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Affiliation(s)
- Barbara Roman
- Cardiac Physiology Lab NHLBI, NIH, Bethesda, Maryland
| | - Yusuf Mastoor
- Cardiac Physiology Lab NHLBI, NIH, Bethesda, Maryland
| | - Junhui Sun
- Cardiac Physiology Lab NHLBI, NIH, Bethesda, Maryland
| | - Hector Chapoy Villanueva
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN
| | | | | | - Julia C. Liu
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN
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2
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Kaye SD, Goyani S, Tomar D. MICU1's calcium sensing beyond mitochondrial calcium uptake. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119714. [PMID: 38555977 PMCID: PMC11194792 DOI: 10.1016/j.bbamcr.2024.119714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 03/19/2024] [Accepted: 03/21/2024] [Indexed: 04/02/2024]
Abstract
The discovery of MICU1 as gatekeeper of mitochondrial calcium (mCa2+) entry has transformed our understanding of mCa2+ flux. Recent studies revealed an additional role of MICU1 as a Ca2+ sensor at MICOS (mitochondrial contact site and cristae organizing system). MICU1's presence at MICOS suggests its involvement in coordinating Ca2+ signaling and mitochondrial ultrastructure. Besides its role in Ca2+ regulation, MICU1 influences cellular signaling pathways including transcription, epigenetic regulation, metabolism, and cell death, thereby affecting human health. Here, we summarize recent findings on MICU1's canonical and noncanonical functions, and its relevance to human health and diseases.
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Affiliation(s)
- Sarah D Kaye
- Department of Internal Medicine, Section of Gerontology and Geriatric Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Shanikumar Goyani
- Department of Internal Medicine, Section of Cardiovascular Medicine, Section of Molecular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Dhanendra Tomar
- Department of Internal Medicine, Section of Cardiovascular Medicine, Section of Molecular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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3
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Stevens TL, Cohen HM, Garbincius JF, Elrod JW. Mitochondrial calcium uniporter channel gatekeeping in cardiovascular disease. NATURE CARDIOVASCULAR RESEARCH 2024; 3:500-514. [PMID: 39185387 PMCID: PMC11343476 DOI: 10.1038/s44161-024-00463-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 03/18/2024] [Indexed: 08/27/2024]
Abstract
The mitochondrial calcium (mCa2+) uniporter channel (mtCU) resides at the inner mitochondrial membrane and is required for Ca2+ to enter the mitochondrial matrix. The mtCU is essential for cellular function, as mCa2+ regulates metabolism, bioenergetics, signaling pathways and cell death. mCa2+ uptake is primarily regulated by the MICU family (MICU1, MICU2, MICU3), EF-hand-containing Ca2+-sensing proteins, which respond to cytosolic Ca2+ concentrations to modulate mtCU activity. Considering that mitochondrial function and Ca2+ signaling are ubiquitously disrupted in cardiovascular disease, mtCU function has been a hot area of investigation for the last decade. Here we provide an in-depth review of MICU-mediated regulation of mtCU structure and function, as well as potential mtCU-independent functions of these proteins. We detail their role in cardiac physiology and cardiovascular disease by highlighting the phenotypes of different mutant animal models, with an emphasis on therapeutic potential and targets of interest in this pathway.
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Affiliation(s)
- Tyler L. Stevens
- Aging + Cardiovascular Discovery Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Henry M. Cohen
- Aging + Cardiovascular Discovery Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Joanne F. Garbincius
- Aging + Cardiovascular Discovery Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - John W. Elrod
- Aging + Cardiovascular Discovery Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
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Skalka GL, Tsakovska M, Murphy DJ. Kinase signalling adaptation supports dysfunctional mitochondria in disease. Front Mol Biosci 2024; 11:1354682. [PMID: 38434478 PMCID: PMC10906720 DOI: 10.3389/fmolb.2024.1354682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 01/15/2024] [Indexed: 03/05/2024] Open
Abstract
Mitochondria form a critical control nexus which are essential for maintaining correct tissue homeostasis. An increasing number of studies have identified dysregulation of mitochondria as a driver in cancer. However, which pathways support and promote this adapted mitochondrial function? A key hallmark of cancer is perturbation of kinase signalling pathways. These pathways include mitogen activated protein kinases (MAPK), lipid secondary messenger networks, cyclic-AMP-activated (cAMP)/AMP-activated kinases (AMPK), and Ca2+/calmodulin-dependent protein kinase (CaMK) networks. These signalling pathways have multiple substrates which support initiation and persistence of cancer. Many of these are involved in the regulation of mitochondrial morphology, mitochondrial apoptosis, mitochondrial calcium homeostasis, mitochondrial associated membranes (MAMs), and retrograde ROS signalling. This review will aim to both explore how kinase signalling integrates with these critical mitochondrial pathways and highlight how these systems can be usurped to support the development of disease. In addition, we will identify areas which require further investigation to fully understand the complexities of these regulatory interactions. Overall, this review will emphasize how studying the interaction between kinase signalling and mitochondria improves our understanding of mitochondrial homeostasis and can yield novel therapeutic targets to treat disease.
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Affiliation(s)
- George L. Skalka
- School of Cancer Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Mina Tsakovska
- School of Cancer Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Daniel J. Murphy
- School of Cancer Sciences, University of Glasgow, Glasgow, United Kingdom
- CRUK Scotland Institute, Glasgow, United Kingdom
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5
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Li X, Sun B, Li J, Ye W, Li M, Guan F, Wu S, Luo X, Feng J, Jia J, Liu X, Li T, Liu L. SEPSIS LEADS TO IMPAIRED MITOCHONDRIAL CALCIUM UPTAKE AND SKELETAL MUSCLE WEAKNESS BY REDUCING THE MICU1:MCU PROTEIN RATIO. Shock 2023; 60:698-706. [PMID: 37695737 PMCID: PMC10662578 DOI: 10.1097/shk.0000000000002221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 05/23/2023] [Accepted: 08/29/2023] [Indexed: 09/13/2023]
Abstract
ABSTRACT Purpose: Intensive care unit-acquired weakness (ICUAW) is a severe neuromuscular complication that frequently occurs in patients with sepsis. The precise molecular pathophysiology of mitochondrial calcium uptake 1 (MICU1) and mitochondrial calcium uniporter (MCU) in ICUAW has not been fully elucidated. Here, we speculate that ICUAW is associated with MICU1:MCU protein ratio-mediated mitochondrial calcium ([Ca 2+ ] m ) uptake dysfunction. Methods: Cecal ligation and perforation (CLP) was performed on C57BL/6J mice to induce sepsis. Sham-operated animals were used as controls. Lipopolysaccharide (LPS) (5 μg/mL) was used to induce inflammation in differentiated C2C12 myoblasts. Compound muscle action potential (CMAP) was detected using a biological signal acquisition system. Grip strength was measured using a grip-strength meter. Skeletal muscle inflammatory factors were detected using ELISA kits. The cross-sectional area (CSA) of the tibialis anterior (TA) muscle was detected by hematoxylin and eosin staining. Cytosolic calcium ([Ca 2+ ] c ) levels were measured using Fluo-4 AM. Adeno-associated virus (AAV) was injected into TA muscles for 4 weeks to overexpress MICU1 prophylactically. A lentivirus was used to infect C2C12 cells to increase MICU1 expression prophylactically. Findings: The results suggest that sepsis induces [Ca 2+ ] m uptake disorder by reducing the MICU1:MCU protein ratio, resulting in skeletal muscle weakness and muscle fiber atrophy. However, MICU1 prophylactic overexpression reversed these effects by increasing the MICU1:MCU protein ratio. Conclusions: ICUAW is associated with impaired [Ca 2+ ] m uptake caused by a decreased MICU1:MCU protein ratio. MICU1 overexpression improves sepsis-induced skeletal muscle weakness and atrophy by ameliorating the [Ca 2+ ] m uptake disorder.
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Affiliation(s)
- Xuexin Li
- Department of Anesthesiology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
- Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, Southwest Medical University, Luzhou, Sichuan Province, China
| | - Bowen Sun
- Department of Anesthesiology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
- Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, Southwest Medical University, Luzhou, Sichuan Province, China
| | - Jie Li
- Department of Anesthesiology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
- Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, Southwest Medical University, Luzhou, Sichuan Province, China
| | - Wanlin Ye
- Laboratory of Mitochondria and Metabolism, West China Hospital of Sichuan University, Chengdu, China
| | - Mingjuan Li
- Department of Anesthesiology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
- Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, Southwest Medical University, Luzhou, Sichuan Province, China
| | - Fasheng Guan
- Department of Anesthesiology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
- Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, Southwest Medical University, Luzhou, Sichuan Province, China
| | - Songlin Wu
- Department of Anesthesiology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
- Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, Southwest Medical University, Luzhou, Sichuan Province, China
| | - Xuerong Luo
- Department of Anesthesiology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
- Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, Southwest Medical University, Luzhou, Sichuan Province, China
| | - Jianguo Feng
- Department of Anesthesiology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
- Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, Southwest Medical University, Luzhou, Sichuan Province, China
| | - Jing Jia
- Department of Anesthesiology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
- Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, Southwest Medical University, Luzhou, Sichuan Province, China
| | - Xueru Liu
- Department of Anesthesiology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
- Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, Southwest Medical University, Luzhou, Sichuan Province, China
| | - Tao Li
- Laboratory of Mitochondria and Metabolism, West China Hospital of Sichuan University, Chengdu, China
| | - Li Liu
- Department of Anesthesiology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
- Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, Southwest Medical University, Luzhou, Sichuan Province, China
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Kumari A, Nguyen DM, Garg V. Patch-clamp technique to study mitochondrial membrane biophysics. J Gen Physiol 2023; 155:e202313347. [PMID: 37347216 PMCID: PMC10287547 DOI: 10.1085/jgp.202313347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 04/12/2023] [Accepted: 06/08/2023] [Indexed: 06/23/2023] Open
Abstract
Mitochondria are double-membrane organelles crucial for oxidative phosphorylation, enabling efficient ATP synthesis by eukaryotic cells. Both of the membranes, the highly selective inner mitochondrial membrane (IMM) and a relatively porous outer membrane (OMM), harbor a number of integral membrane proteins that help in the transport of biological molecules. These transporters are especially enriched in the IMM, where they help maintain transmembrane gradients for H+, K+, Ca2+, PO43-, and metabolites like ADP/ATP, citrate, etc. Impaired activity of these transporters can affect the efficiency of energy-transducing processes and can alter cellular redox state, leading to activation of cell-death pathways or metabolic syndromes in vivo. Although several methodologies are available to study ion flux through membrane proteins, the patch-clamp technique remains the gold standard for quantitatively analyzing electrogenic ion exchange across membranes. Direct patch-clamp recordings of mitoplasts (mitochondria devoid of outer membrane) in different modes, such as whole-mitoplast or excised-patch mode, allow researchers the opportunity to study the biophysics of mitochondrial transporters in the native membrane, in real time, in isolation from other fluxes or confounding factors due to changes in ion gradients, pH, or mitochondrial potential (ΔΨ). Here, we summarize the use of patch clamp to investigate several membrane proteins of mitochondria. We demonstrate how this technique can be reliably applied to record whole-mitoplast Ca2+ currents mediated via mitochondrial calcium uniporter or H+ currents mediated by uncoupling protein 1 and discuss critical considerations while recording currents from these small vesicles of the IMM (mitoplast diameter = 2-5 µm).
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Affiliation(s)
- Anshu Kumari
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Baltimore, MD, USA
| | - Dung M. Nguyen
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Baltimore, MD, USA
| | - Vivek Garg
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Baltimore, MD, USA
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7
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Miao Y, Wang X, Lai Y, Huang Y, Yin H, Meng X, Liu H, Hou R, Lin W, Zhang X, Zhang X, Chai BC, Zhang F, Guo L, Yang S. Targeting the mitochondrial calcium uniporter inhibits cancer progression and alleviates cisplatin resistance in esophageal squamous cell carcinoma. Int J Oncol 2023; 63:82. [PMID: 37264968 PMCID: PMC10552700 DOI: 10.3892/ijo.2023.5530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Accepted: 05/05/2023] [Indexed: 06/03/2023] Open
Abstract
Cisplatin is the standard chemotherapeutic drug used for the treatment of esophageal squamous cell carcinoma (ESCC). Acquired cisplatin resistance is the primary obstacle to prolonging patient survival time. Here, the therapeutic effects of mitochondrial calcium uniporter (MCU) inhibition on tumor growth and cisplatin resistance in ESCC were assessed. MCU was stably overexpressed or knocked down in three ESCC cell lines and three cisplatin‑resistant ESCC cell lines. Then, proliferation, migration, and mitochondrial membrane potential (MMP) were measured by colony formation, wound healing, Transwell, and JC‑1 staining assays. MCU, MICU2, MICU1, and PD‑L1 levels were detected through western blotting and immunofluorescence. ESCC and cisplatin‑resistant ESCC xenograft mouse models were established. After MCU knockdown, tumor volume was measured. The expression levels of proliferation markers (CyclinD1 and Ki‑67), MICU1/2, PD‑L1, epithelial-mesenchymal transition (EMT) markers (vimentin, β‑catenin, and E‑cadherin), and the angiogenesis marker CD34 were detected through western blotting, immunohistochemistry, or immunofluorescence. The results showed that MCU overexpression significantly promoted proliferation, migration, and MMP in ESCC cells and cisplatin‑resistant ESCC cells. However, proliferation, migration, and MMP were suppressed following MCU knockdown. In ESCC cells, MCU overexpression markedly increased MICU2, MICU1, and PD‑L1 levels, and the opposite results were observed when MCU was stably knocked down. Similarly, MCU inhibition decreased MICU2, MICU1, and PD‑L1 expression in cisplatin‑resistant ESCC cells. Moreover, MCU knockdown substantially decreased tumor growth, EMT, and angiogenesis in ESCC and cisplatin‑resistant ESCC xenograft mice. Collectively, targeting MCU may inhibit cancer progression and alleviate cisplatin resistance in ESCC.
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Affiliation(s)
- Yu Miao
- Department of Gastroenterology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004
| | - Xiaofei Wang
- Pathology Department, North China University of Science and Technology Affiliated Hospital, Tangshan, Hebie 063000
| | - Yafang Lai
- Department of Gastroenterology, Ordos Central Hospital, Ordos, Inner Mongolia Autonomous Region 017000
| | - Ying Huang
- Department of Gastroenterology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004
| | - Hua Yin
- Department of Gastroenterology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004
| | - Xiangkun Meng
- Department of Gastroenterology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004
| | - Hao Liu
- Department of Gastroenterology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004
| | - Ruirui Hou
- Department of Gastroenterology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004
| | - Wan Lin
- Department of Gastroenterology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004
| | - Xiaoxu Zhang
- Department of Gastroenterology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004
| | - Xu Zhang
- Department of Gastroenterology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004
| | - Bei Cho Chai
- Department of Gastroenterology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004
| | - Feixiong Zhang
- Department of Gastroenterology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004
| | - Le Guo
- Department of Medical Laboratory, School of Clinical Medicine, Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004, P.R. China
| | - Shaoqi Yang
- Department of Gastroenterology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004
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8
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Chan C, Yuan CC, McCoy JG, Ward PS, Grabarek Z. The mitochondrial calcium uniporter transports Ca 2+ via a ligand-relay mechanism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.17.545435. [PMID: 37398228 PMCID: PMC10312793 DOI: 10.1101/2023.06.17.545435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
The mitochondrial calcium uniporter (mtCU) is a multicomponent Ca 2+ -specific channel that imparts mitochondria with the capacity to sense the cytosolic calcium signals. The metazoan mtCU comprises the pore-forming subunit MCU and the essential regulator EMRE, arranged in a tetrameric channel complex, and the Ca 2+ sensing peripheral proteins MICU1-3. The mechanism of mitochondrial Ca 2+ uptake by mtCU and its regulation is poorly understood. Our analysis of MCU structure and sequence conservation, combined with molecular dynamics simulations, mutagenesis, and functional studies, led us to conclude that the Ca 2+ conductance of MCU is driven by a ligand-relay mechanism, which depends on stochastic structural fluctuations in the conserved DxxE sequence. In the tetrameric structure of MCU, the four glutamate side chains of DxxE (the E-ring) chelate Ca 2+ directly in a high-affinity complex (site 1), which blocks the channel. The four glutamates can also switch to a hydrogen bond-mediated interaction with an incoming hydrated Ca 2+ transiently sequestered within the D-ring of DxxE (site 2), thus releasing the Ca 2+ bound at site 1. This process depends critically on the structural flexibility of DxxE imparted by the adjacent invariant Pro residue. Our results suggest that the activity of the uniporter can be regulated through the modulation of local structural dynamics. A preliminary account of this work was presented at the 67 th Annual Meeting of the Biophysical Society in San Diego, CA, February 18-22, 2023.
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9
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Rodríguez-Prados M, Huang KT, Márta K, Paillard M, Csordás G, Joseph SK, Hajnóczky G. MICU1 controls the sensitivity of the mitochondrial Ca 2+ uniporter to activators and inhibitors. Cell Chem Biol 2023; 30:606-617.e4. [PMID: 37244260 PMCID: PMC10370359 DOI: 10.1016/j.chembiol.2023.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 02/28/2023] [Accepted: 05/05/2023] [Indexed: 05/29/2023]
Abstract
Mitochondrial Ca2+ homeostasis loses its control in many diseases and might provide therapeutic targets. Mitochondrial Ca2+ uptake is mediated by the uniporter channel (mtCU), formed by MCU and is regulated by the Ca2+-sensing gatekeeper, MICU1, which shows tissue-specific stoichiometry. An important gap in knowledge is the molecular mechanism of the mtCU activators and inhibitors. We report that all pharmacological activators of the mtCU (spermine, kaempferol, SB202190) act in a MICU1-dependent manner, likely by binding to MICU1 and preventing MICU1's gatekeeping activity. These agents also sensitized the mtCU to inhibition by Ru265 and enhanced the Mn2+-induced cytotoxicity as previously seen with MICU1 deletion. Thus, MCU gating by MICU1 is the target of mtCU agonists and is a barrier for inhibitors like RuRed/Ru360/Ru265. The varying MICU1:MCU ratios result in different outcomes for both mtCU agonists and antagonists in different tissues, which is relevant for both pre-clinical research and therapeutic efforts.
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Affiliation(s)
- Macarena Rodríguez-Prados
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Kai-Ting Huang
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Katalin Márta
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Melanie Paillard
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - György Csordás
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Suresh K Joseph
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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10
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Tu YC, Chao FY, Tsai MF. Mechanisms of dual modulatory effects of spermine on the mitochondrial calcium uniporter complex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.06.543936. [PMID: 37333420 PMCID: PMC10274775 DOI: 10.1101/2023.06.06.543936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
The mitochondrial Ca 2 + uniporter mediates the crucial cellular process of mitochondrial Ca 2 + uptake, which regulates cell bioenergetics, intracellular Ca 2 + signaling, and cell death initiation. The uniporter contains the pore-forming MCU subunit, an EMRE protein that binds to MCU, and the regulatory MICU1 subunit, which can dimerize with MICU1 or MICU2 and under resting cellular [Ca 2 + ] occludes the MCU pore. It has been known for decades that spermine, which is ubiquitously present in animal cells, can enhance mitochondrial Ca 2 + uptake, but the underlying mechanisms remain unclear. Here, we show that spermine exerts dual modulatory effects on the uniporter. In physiological concentrations of spermine, it enhances uniporter activity by breaking the physical interactions between MCU and the MICU1-containing dimers to allow the uniporter to constitutively take up Ca 2 + even in low [Ca 2 + ] conditions. This potentiation effect does not require MICU2 or the EF-hand motifs in MICU1. When [spermine] rises to millimolar levels, it inhibits the uniporter by targeting the pore region in a MICU-independent manner. The MICU1-dependent spermine potentiation mechanism proposed here, along with our previous finding that cardiac mitochondria have very low MICU1, can explain the puzzling observation in the literature that mitochondria in the heart show no response to spermine.
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Affiliation(s)
- Yung-Chi Tu
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Fan-Yi Chao
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Ming-Feng Tsai
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
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11
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Seegren PV, Harper LR, Downs TK, Zhao XY, Viswanathan SB, Stremska ME, Olson RJ, Kennedy J, Ewald SE, Kumar P, Desai BN. Reduced mitochondrial calcium uptake in macrophages is a major driver of inflammaging. NATURE AGING 2023:10.1038/s43587-023-00436-8. [PMID: 37277641 DOI: 10.1038/s43587-023-00436-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 05/09/2023] [Indexed: 06/07/2023]
Abstract
Mitochondrial dysfunction is linked to age-associated inflammation or inflammaging, but underlying mechanisms are not understood. Analyses of 700 human blood transcriptomes revealed clear signs of age-associated low-grade inflammation. Among changes in mitochondrial components, we found that the expression of mitochondrial calcium uniporter (MCU) and its regulatory subunit MICU1, genes central to mitochondrial Ca2+ (mCa2+) signaling, correlated inversely with age. Indeed, mCa2+ uptake capacity of mouse macrophages decreased significantly with age. We show that in both human and mouse macrophages, reduced mCa2+ uptake amplifies cytosolic Ca2+ oscillations and potentiates downstream nuclear factor kappa B activation, which is central to inflammation. Our findings pinpoint the mitochondrial calcium uniporter complex as a keystone molecular apparatus that links age-related changes in mitochondrial physiology to systemic macrophage-mediated age-associated inflammation. The findings raise the exciting possibility that restoring mCa2+ uptake capacity in tissue-resident macrophages may decrease inflammaging of specific organs and alleviate age-associated conditions such as neurodegenerative and cardiometabolic diseases.
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Affiliation(s)
- Philip V Seegren
- Pharmacology Department, University of Virginia School of Medicine, Charlottesville, VA, USA
- Carter Immunology Center, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Logan R Harper
- Pharmacology Department, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Taylor K Downs
- Pharmacology Department, University of Virginia School of Medicine, Charlottesville, VA, USA
- Carter Immunology Center, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Xiao-Yu Zhao
- Carter Immunology Center, University of Virginia School of Medicine, Charlottesville, VA, USA
- Microbiology, Immunology, and Cancer Biology Department, University of Virginia School of Medicine, Charlottesville, VA, USA
| | | | - Marta E Stremska
- Carter Immunology Center, University of Virginia School of Medicine, Charlottesville, VA, USA
- Microbiology, Immunology, and Cancer Biology Department, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Rachel J Olson
- Pharmacology Department, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Joel Kennedy
- Pharmacology Department, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Sarah E Ewald
- Carter Immunology Center, University of Virginia School of Medicine, Charlottesville, VA, USA
- Microbiology, Immunology, and Cancer Biology Department, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Pankaj Kumar
- Biochemistry and Molecular Genetics Department, University of Virginia School of Medicine, Charlottesville, VA, USA
- University of Virginia, Bioinformatics Core, Charlottesville, VA, USA
| | - Bimal N Desai
- Pharmacology Department, University of Virginia School of Medicine, Charlottesville, VA, USA.
- Carter Immunology Center, University of Virginia School of Medicine, Charlottesville, VA, USA.
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12
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Gottschalk B, Malli R, Graier WF. MICU1 deficiency alters mitochondrial morphology and cytochrome C release. Cell Calcium 2023; 113:102765. [PMID: 37290367 DOI: 10.1016/j.ceca.2023.102765] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 05/28/2023] [Accepted: 05/31/2023] [Indexed: 06/10/2023]
Abstract
The mitochondrial inner boundary membrane harbors a protein called MICU1, which is sensitive to Ca2+ and binds to the MICOS components Mic60 and CHCHD2. Changes in the mitochondrial cristae junction structure and organization in MICU1-/- cells lead to increased cytochrome c release, membrane potential rearrangement, and changes in mitochondrial Ca2+ uptake dynamics. These findings shed new light on the multifaceted role of MICU1, highlighting its involvement not only as an interaction partner and regulator of the MCU complex but also as a crucial determinant of mitochondrial ultrastructure and, thus, an essential player in processes initiating apoptosis.
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Affiliation(s)
- Benjamin Gottschalk
- Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/4, Graz, 8010 Austria
| | - Roland Malli
- Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/4, Graz, 8010 Austria; BioTechMed, Graz, Austria
| | - Wolfgang F Graier
- Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/4, Graz, 8010 Austria; BioTechMed, Graz, Austria.
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13
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De Mario A, D'Angelo D, Zanotti G, Raffaello A, Mammucari C. The mitochondrial calcium uniporter complex–A play in five acts. Cell Calcium 2023; 112:102720. [PMID: 37001308 DOI: 10.1016/j.ceca.2023.102720] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 03/22/2023] [Accepted: 03/23/2023] [Indexed: 03/30/2023]
Abstract
Mitochondrial Ca2+ (mitCa2+) uptake controls both intraorganellar and cytosolic functions. Within the organelle, [Ca2+] increases regulate the activity of tricarboxylic acid (TCA) cycle enzymes, thus sustaining oxidative metabolism and ATP production. Reactive oxygen species (ROS) are also generated as side products of oxygen consumption. At the same time, mitochondria act as buffers of cytosolic Ca2+ (cytCa2+) increases, thus regulating Ca2+-dependent cellular processes. In pathological conditions, mitCa2+ overload triggers the opening of the mitochondrial permeability transition pore (mPTP) and the release of apoptotic cofactors. MitCa2+ uptake occurs in response of local [Ca2+] increases in sites of proximity between the endoplasmic reticulum (ER) and the mitochondria and is mediated by the mitochondrial Ca2+ uniporter (MCU), a highly selective channel of the inner mitochondrial membrane (IMM). Both channel and regulatory subunits form the MCU complex (MCUC). Cryogenic electron microscopy (Cryo-EM) and crystal structures revealed the correct assembly of MCUC and the function of critical residues for the regulation of Ca2+ conductance.
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14
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Rodríguez-Prados M, Berezhnaya E, Castromonte MT, Menezes-Filho SL, Paillard M, Hajnóczky G. MICU1 occludes the mitochondrial calcium uniporter in divalent-free conditions. Proc Natl Acad Sci U S A 2023; 120:e2218999120. [PMID: 37126688 PMCID: PMC10175726 DOI: 10.1073/pnas.2218999120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 03/30/2023] [Indexed: 05/03/2023] Open
Abstract
Mitochondrial Ca2+ uptake is mediated by the mitochondrial uniporter complex (mtCU) that includes a tetramer of the pore-forming subunit, MCU, a scaffold protein, EMRE, and the EF-hand regulatory subunit, MICU1 either homodimerized or heterodimerized with MICU2/3. MICU1 has been proposed to regulate Ca2+ uptake via the mtCU by physically occluding the pore and preventing Ca2+ flux at resting cytoplasmic [Ca2+] (free calcium concentration) and to increase Ca2+ flux at high [Ca2+] due to cooperative activation of MICUs EF-hands. However, mtCU and MICU1 functioning when its EF-hands are unoccupied by Ca2+ is poorly studied due to technical limitations. To overcome this barrier, we have studied the mtCU in divalent-free conditions by assessing the Ru265-sensitive Na+ influx using fluorescence-based measurement of mitochondrial matrix [Na+] (free sodium concentration) rise and the ensuing depolarization and swelling. We show an increase in all these measures of Na+ uptake in MICU1KO cells as compared to wild-type (WT) and rescued MICU1KO HEK cells. However, mitochondria in WT cells and MICU1 stable-rescued cells still allowed some Ru265-sensitive Na+ influx that was prevented by MICU1 in excess upon acute overexpression. Thus, MICU1 restricts the cation flux across the mtCU in the absence of Ca2+, but even in cells with high endogenous MICU1 expression such as HEK, some mtCU seem to lack MICU1-dependent gating. We also show rearrangement of the mtCU and altered number of functional channels in MICU1KO and different rescues, and loss of MICU1 during mitoplast preparation, that together might have obscured the pore-blocking function of MICU1 in divalent-free conditions in previous studies.
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Affiliation(s)
- Macarena Rodríguez-Prados
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Elena Berezhnaya
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Maria Teresa Castromonte
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Sergio L. Menezes-Filho
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Melanie Paillard
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA19107
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15
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Tomar D, Thomas M, Garbincius JF, Kolmetzky DW, Salik O, Jadiya P, Joseph SK, Carpenter AC, Hajnóczky G, Elrod JW. MICU1 regulates mitochondrial cristae structure and function independently of the mitochondrial Ca 2+ uniporter channel. Sci Signal 2023; 16:eabi8948. [PMID: 37098122 PMCID: PMC10388395 DOI: 10.1126/scisignal.abi8948] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 03/30/2023] [Indexed: 04/27/2023]
Abstract
MICU1 is a calcium (Ca2+)-binding protein that regulates the mitochondrial Ca2+ uniporter channel complex (mtCU) and mitochondrial Ca2+ uptake. MICU1 knockout mice display disorganized mitochondrial architecture, a phenotype that is distinct from that of mice with deficiencies in other mtCU subunits and, thus, is likely not explained by changes in mitochondrial matrix Ca2+ content. Using proteomic and cellular imaging techniques, we found that MICU1 localized to the mitochondrial contact site and cristae organizing system (MICOS) and directly interacted with the MICOS components MIC60 and CHCHD2 independently of the mtCU. We demonstrated that MICU1 was essential for MICOS complex formation and that MICU1 ablation resulted in altered cristae organization, mitochondrial ultrastructure, mitochondrial membrane dynamics, and cell death signaling. Together, our results suggest that MICU1 is an intermembrane space Ca2+ sensor that modulates mitochondrial membrane dynamics independently of matrix Ca2+ uptake. This system enables distinct Ca2+ signaling in the mitochondrial matrix and at the intermembrane space to modulate cellular energetics and cell death in a concerted manner.
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Affiliation(s)
- Dhanendra Tomar
- Cardiovascular Research Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140
| | - Manfred Thomas
- Cardiovascular Research Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140
| | - Joanne F. Garbincius
- Cardiovascular Research Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140
| | - Devin W. Kolmetzky
- Cardiovascular Research Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140
| | - Oniel Salik
- Cardiovascular Research Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140
- Health and Exercise Physiology, Ursinus College, Collegeville, PA 19426, USA
| | - Pooja Jadiya
- Cardiovascular Research Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140
| | - Suresh K. Joseph
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - April C. Carpenter
- Health and Exercise Physiology, Ursinus College, Collegeville, PA 19426, USA
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - John W. Elrod
- Cardiovascular Research Center, Department of Cardiovascular Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140
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16
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Tsai CW, Liu TY, Chao FY, Tu YC, Rodriguez MX, Van Keuren AM, Ma Z, Bankston J, Tsai MF. Evidence supporting the MICU1 occlusion mechanism and against the potentiation model in the mitochondrial calcium uniporter complex. Proc Natl Acad Sci U S A 2023; 120:e2217665120. [PMID: 37036971 PMCID: PMC10120041 DOI: 10.1073/pnas.2217665120] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 03/03/2023] [Indexed: 04/12/2023] Open
Abstract
The mitochondrial calcium uniporter is a Ca2+ channel that imports cytoplasmic Ca2+ into the mitochondrial matrix to regulate cell bioenergetics, intracellular Ca2+ signaling, and apoptosis. The uniporter contains the pore-forming MCU subunit, an auxiliary EMRE protein, and the regulatory MICU1/MICU2 subunits. Structural and biochemical studies have suggested that MICU1 gates MCU by blocking/unblocking the pore. However, mitoplast patch-clamp experiments argue that MICU1 does not block, but instead potentiates MCU via allosteric mechanisms. Here, we address this direct clash of the proposed MICU1 function. Supporting the MICU1-occlusion mechanism, patch-clamp demonstrates that purified MICU1 strongly suppresses MCU Ca2+ currents, and this inhibition is abolished by mutating the MCU-interacting K126 residue. Moreover, a membrane-depolarization assay shows that MICU1 prevents MCU-mediated Na+ flux into intact mitochondria under Ca2+-free conditions. Examining the observations underlying the potentiation model, we found that MICU1 occlusion was not detected in mitoplasts not because MICU1 cannot block, but because MICU1 dissociates from the uniporter complex. Furthermore, MICU1 depletion reduces uniporter transport not because MICU1 can potentiate MCU, but because EMRE is down-regulated. These results firmly establish the molecular mechanisms underlying the physiologically crucial process of uniporter regulation by MICU1.
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Affiliation(s)
- Chen-Wei Tsai
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO80045
| | - Tsung-Yun Liu
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO80045
| | - Fan-Yi Chao
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO80045
| | - Yung-Chi Tu
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO80045
| | - Madison X. Rodriguez
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO80045
| | - Anna M. Van Keuren
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO80045
| | - Zhiwei Ma
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO65211
| | - John Bankston
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO80045
| | - Ming-Feng Tsai
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO80045
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17
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Sánchez-Aguilera P, López-Crisosto C, Norambuena-Soto I, Penannen C, Zhu J, Bomer N, Hoes MF, Van Der Meer P, Chiong M, Westenbrink BD, Lavandero S. IGF-1 boosts mitochondrial function by a Ca 2+ uptake-dependent mechanism in cultured human and rat cardiomyocytes. Front Physiol 2023; 14:1106662. [PMID: 36846332 PMCID: PMC9944404 DOI: 10.3389/fphys.2023.1106662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 01/23/2023] [Indexed: 02/10/2023] Open
Abstract
A physiological increase in cardiac workload results in adaptive cardiac remodeling, characterized by increased oxidative metabolism and improvements in cardiac performance. Insulin-like growth factor-1 (IGF-1) has been identified as a critical regulator of physiological cardiac growth, but its precise role in cardiometabolic adaptations to physiological stress remains unresolved. Mitochondrial calcium (Ca2+) handling has been proposed to be required for sustaining key mitochondrial dehydrogenase activity and energy production during increased workload conditions, thus ensuring the adaptive cardiac response. We hypothesized that IGF-1 enhances mitochondrial energy production through a Ca2+-dependent mechanism to ensure adaptive cardiomyocyte growth. We found that stimulation with IGF-1 resulted in increased mitochondrial Ca2+ uptake in neonatal rat ventricular myocytes and human embryonic stem cell-derived cardiomyocytes, estimated by fluorescence microscopy and indirectly by a reduction in the pyruvate dehydrogenase phosphorylation. We showed that IGF-1 modulated the expression of mitochondrial Ca2+ uniporter (MCU) complex subunits and increased the mitochondrial membrane potential; consistent with higher MCU-mediated Ca2+ transport. Finally, we showed that IGF-1 improved mitochondrial respiration through a mechanism dependent on MCU-mediated Ca2+ transport. In conclusion, IGF-1-induced mitochondrial Ca2+ uptake is required to boost oxidative metabolism during cardiomyocyte adaptive growth.
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Affiliation(s)
- Pablo Sánchez-Aguilera
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas, Facultad de Medicina, Universidad de Chile, Santiago, Chile,Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Camila López-Crisosto
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Ignacio Norambuena-Soto
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Christian Penannen
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Jumo Zhu
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Nils Bomer
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Matijn F. Hoes
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, Netherlands,Department of Genetics and Cell Biology, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Netherlands,CARIM School for Cardiovascular Diseases, Maastricht, Netherlands
| | - Peter Van Der Meer
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Mario Chiong
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - B. Daan Westenbrink
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands,*Correspondence: B. Daan Westenbrink, ; Sergio Lavandero,
| | - Sergio Lavandero
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas, Facultad de Medicina, Universidad de Chile, Santiago, Chile,Cardiology Division, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States,*Correspondence: B. Daan Westenbrink, ; Sergio Lavandero,
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18
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Delgado BD, Long SB. Mechanisms of ion selectivity and throughput in the mitochondrial calcium uniporter. SCIENCE ADVANCES 2022; 8:eade1516. [PMID: 36525497 PMCID: PMC9757755 DOI: 10.1126/sciadv.ade1516] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 11/17/2022] [Indexed: 06/17/2023]
Abstract
The mitochondrial calcium uniporter, which regulates aerobic metabolism by catalyzing mitochondrial Ca2+ influx, is arguably the most selective ion channel known. The mechanisms for this exquisite Ca2+ selectivity have not been defined. Here, using a reconstituted system, we study the electrical properties of the channel's minimal Ca2+-conducting complex, MCU-EMRE, from Tribolium castaneum to probe ion selectivity mechanisms. The wild-type TcMCU-EMRE complex recapitulates hallmark electrophysiological properties of endogenous Uniporter channels. Through interrogation of pore-lining mutants, we find that a ring of glutamate residues, the "E-locus," serves as the channel's selectivity filter. Unexpectedly, a nearby "D-locus" at the mouth of the pore has diminutive influence on selectivity. Anomalous mole fraction effects indicate that multiple Ca2+ ions are accommodated within the E-locus. By facilitating ion-ion interactions, the E-locus engenders both exquisite Ca2+ selectivity and high ion throughput. Direct comparison with structural information yields the basis for selective Ca2+ conduction by the channel.
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Affiliation(s)
- Bryce D. Delgado
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
- Graduate Program in Biochemistry and Structural Biology, Cell and Developmental Biology, and Molecular Biology, Weill Cornell Medicine Graduate School of Medical Sciences, New York, NY 10065, USA
| | - Stephen B. Long
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
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19
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Yoo J. Structural basis of Ca 2+ uptake by mitochondrial calcium uniporter in mitochondria: a brief review. BMB Rep 2022; 55:528-534. [PMID: 36195565 PMCID: PMC9712701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Indexed: 12/14/2022] Open
Abstract
Mitochondria are cellular organelles that perform various functions within cells. They are responsible for ATP production, cell-signal regulation, autophagy, and cell apoptosis. Because the mitochondrial proteins that perform these functions need Ca2+ ions for their activity, mitochondria have ion channels to selectively uptake Ca2+ ions from the cytoplasm. The ion channel known to play the most important role in the Ca2+ uptake in mitochondria is the mitochondrial calcium uniporter (MCU) holo-complex located in the inner mitochondrial membrane (IMM). This ion channel complex exists in the form of a complex consisting of the pore-forming protein through which the Ca2+ ions are transported into the mitochondrial matrix, and the auxiliary protein involved in regulating the activity of the Ca2+ uptake by the MCU holo-complex. Studies of this MCU holocomplex have long been conducted, but we didn't know in detail how mitochondria uptake Ca2+ ions through this ion channel complex or how the activity of this ion channel complex is regulated. Recently, the protein structure of the MCU holo-complex was identified, enabling the mechanism of Ca2+ uptake and its regulation by the MCU holo-complex to be confirmed. In this review, I will introduce the mechanism of action of the MCU holo-complex at the molecular level based on the Cryo-EM structure of the MCU holo-complex to help understand how mitochondria uptake the necessary Ca2+ ions through the MCU holo-complex and how these Ca2+ uptake mechanisms are regulated. [BMB Reports 2022; 55(11): 528-534].
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Affiliation(s)
- Jiho Yoo
- College of Pharmacy, Chung-Ang University, Seoul 06974, Korea,Corresponding author. Tel: +82-2-820-5673; E-mail:
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20
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Yoo J. Structural basis of Ca 2+ uptake by mitochondrial calcium uniporter in mitochondria: a brief review. BMB Rep 2022; 55:528-534. [PMID: 36195565 PMCID: PMC9712701 DOI: 10.5483/bmbrep.2022.55.11.134] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 09/16/2022] [Accepted: 09/30/2022] [Indexed: 03/17/2024] Open
Abstract
Mitochondria are cellular organelles that perform various functions within cells. They are responsible for ATP production, cell-signal regulation, autophagy, and cell apoptosis. Because the mitochondrial proteins that perform these functions need Ca2+ ions for their activity, mitochondria have ion channels to selectively uptake Ca2+ ions from the cytoplasm. The ion channel known to play the most important role in the Ca2+ uptake in mitochondria is the mitochondrial calcium uniporter (MCU) holo-complex located in the inner mitochondrial membrane (IMM). This ion channel complex exists in the form of a complex consisting of the pore-forming protein through which the Ca2+ ions are transported into the mitochondrial matrix, and the auxiliary protein involved in regulating the activity of the Ca2+ uptake by the MCU holo-complex. Studies of this MCU holocomplex have long been conducted, but we didn't know in detail how mitochondria uptake Ca2+ ions through this ion channel complex or how the activity of this ion channel complex is regulated. Recently, the protein structure of the MCU holo-complex was identified, enabling the mechanism of Ca2+ uptake and its regulation by the MCU holo-complex to be confirmed. In this review, I will introduce the mechanism of action of the MCU holo-complex at the molecular level based on the Cryo-EM structure of the MCU holo-complex to help understand how mitochondria uptake the necessary Ca2+ ions through the MCU holo-complex and how these Ca2+ uptake mechanisms are regulated. [BMB Reports 2022; 55(11): 528-534].
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Affiliation(s)
- Jiho Yoo
- College of Pharmacy, Chung-Ang University, Seoul 06974, Korea
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21
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Bertolini MS, Docampo R. MICU1 and MICU2 potentiation of Ca 2+ uptake by the mitochondrial Ca 2+ uniporter of Trypanosoma cruzi and its inhibition by Mg 2. Cell Calcium 2022; 107:102654. [PMID: 36166935 PMCID: PMC10433726 DOI: 10.1016/j.ceca.2022.102654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 09/16/2022] [Accepted: 09/19/2022] [Indexed: 11/30/2022]
Abstract
The mitochondrial Ca2+ uptake, which is important to regulate bioenergetics, cell death and cytoplasmic Ca2+ signaling, is mediated via the calcium uniporter complex (MCUC). In animal cells the MCUC is regulated by the mitochondrial calcium uptake 1 and 2 dimer (MICU1/MICU2), which has been proposed to act as gatekeeper preventing mitochondrial Ca2+ overload at low cytosolic Ca2+ levels. In contrast to animal cells, knockout of either MICU1 or MICU2 in Trypanosoma cruzi, the etiologic agent of Chagas disease, did not allow Ca2+ uptake at low extramitochondrial Ca2+ concentrations ([Ca2+]ext) and it was though that in the absence of one MICU the other would replace its role. However, previous attempts to knockout both genes were unsuccessful. Here, we designed a strategy to generate TcMICU1/TcMICU2 double knockout cell lines using CRISPR/Cas9 genome editing. Ablation of both genes was confirmed by PCR and Southern blot analyses. The absence of both proteins did not allow Ca2+ uptake at low [Ca2+]ext, significantly decreased the mitochondrial Ca2+ uptake at different [Ca2+]ext, without dissipation of the mitochondrial membrane potential, and increased the [Ca2+]ext set point needed for Ca2+ uptake, as we have seen with TcMICU1-KO and TcMICU2-KO cells. Mg2+ was found to be a negative regulator of MCUC-mediated mitochondrial Ca2+ uptake at different [Ca2+]ext. Occlusion of the MCUC pore by Mg2+ could partially explain the lack of mitochondrial Ca2+ uptake at low [Ca2+]ext in TcMICU1/TcMICU2-KO cells. In addition, TcMICU1/TcMICU2-KO epimastigotes had a lower growth rate, while infective trypomastigotes have a reduced capacity to invade host cells and to replicate within them as amastigotes.
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Affiliation(s)
- Mayara S Bertolini
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA, United States
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA, United States.
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22
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Gottschalk B, Koshenov Z, Waldeck-Weiermair M, Radulović S, Oflaz FE, Hirtl M, Bachkoenig OA, Leitinger G, Malli R, Graier WF. MICU1 controls spatial membrane potential gradients and guides Ca 2+ fluxes within mitochondrial substructures. Commun Biol 2022; 5:649. [PMID: 35778442 PMCID: PMC9249747 DOI: 10.1038/s42003-022-03606-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 06/17/2022] [Indexed: 01/19/2023] Open
Abstract
Mitochondrial ultrastructure represents a pinnacle of form and function, with the inner mitochondrial membrane (IMM) forming isolated pockets of cristae membrane (CM), separated from the inner-boundary membrane (IBM) by cristae junctions (CJ). Applying structured illumination and electron microscopy, a novel and fundamental function of MICU1 in mediating Ca2+ control over spatial membrane potential gradients (SMPGs) between CM and IMS was identified. We unveiled alterations of SMPGs by transient CJ openings when Ca2+ binds to MICU1 resulting in spatial cristae depolarization. This Ca2+/MICU1-mediated plasticity of the CJ further provides the mechanistic bedrock of the biphasic mitochondrial Ca2+ uptake kinetics via the mitochondrial Ca2+ uniporter (MCU) during intracellular Ca2+ release: Initially, high Ca2+ opens CJ via Ca2+/MICU1 and allows instant Ca2+ uptake across the CM through constantly active MCU. Second, MCU disseminates into the IBM, thus establishing Ca2+ uptake across the IBM that circumvents the CM. Under the condition of MICU1 methylation by PRMT1 in aging or cancer, UCP2 that binds to methylated MICU1 destabilizes CJ, disrupts SMPGs, and facilitates fast Ca2+ uptake via the CM.
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Affiliation(s)
- Benjamin Gottschalk
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Zhanat Koshenov
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Markus Waldeck-Weiermair
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Snježana Radulović
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Furkan E. Oflaz
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Martin Hirtl
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Olaf A. Bachkoenig
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Gerd Leitinger
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Roland Malli
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria ,grid.452216.6BioTechMed Graz, Graz, Austria
| | - Wolfgang F. Graier
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria ,grid.452216.6BioTechMed Graz, Graz, Austria
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Dong Z, Wang J, Qiu T, Wu J, An Y, Shi X, Sun X, Jiang L, Liu X, Yang G, Cao J, Yao X. Perfluorooctane sulfonate induces mitochondrial calcium overload and early hepatic insulin resistance via autophagy/detyrosinated alpha-tubulin-regulated IP3R2-VDAC1-MICU1 interaction. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 825:153933. [PMID: 35192817 DOI: 10.1016/j.scitotenv.2022.153933] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 02/11/2022] [Accepted: 02/12/2022] [Indexed: 06/14/2023]
Abstract
Perfluorooctane sulfonate (PFOS), one kind of persistent organic pollutants, is associated with insulin resistance (IR) in general population. However, the exact mechanism is still obscure. In this study, we found that 50 μM PFOS caused IR in L-02 hepatocytes after 1 h, and induced autophagy and mitochondrial calcium (Ca2+) accumulation as early as 0.5 h. Inhibiting autophagy relieved mitochondrial Ca2+ overload and then reversed IR. Mitochondria were aggregated at cell periphery, and extracellular Ca2+ from IP3R2 on the plasma membrane, rather than endoplasmic reticulum Ca2+, was the priority source of mitochondrial Ca2+ uptake at early stages of PFOS exposure. Furthermore, we discovered that the linkage connecting autophagy and mitochondrial Ca2+ response was detyrosinated α-tubulin, which autophagy-dependently ascended, interacted with VDAC1 and enhanced the formation of IP3R2-VDAC1-MICU1 complex. Consistently, PFOS caused IR, activated autophagy, induced mitochondrial Ca2+ overload, increased the level of detyrosinated α-tubulin, and promoted the formation of IP3R2-VDAC1-MICU1 complex in the liver of C57BL/6J mice exposed to 2.5 mg/kg/day PFOS for 6 weeks. This study clarified that autophagy and mitochondrial Ca2+ accumulation were the early and triggering event that caused PFOS-related IR, also unveiled a novel mechanism regulating mitochondrial Ca2+ homeostasis.
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Affiliation(s)
- Zhanchen Dong
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Jianyu Wang
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Tianming Qiu
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Jialu Wu
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Yu An
- Dalian Municipal Center for Disease Control and Prevention, 151 Yueling West Street, Ganjingzi District, Dalian 116037, PR China
| | - Xiaoxia Shi
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Xiance Sun
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Liping Jiang
- Department of Food Nutrition and Safety, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Xiaofang Liu
- Department of Food Nutrition and Safety, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Guang Yang
- Department of Food Nutrition and Safety, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Jun Cao
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China
| | - Xiaofeng Yao
- Department of Occupational and Environmental Health, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, PR China.
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24
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Garbincius JF, Elrod JW. Mitochondrial calcium exchange in physiology and disease. Physiol Rev 2022; 102:893-992. [PMID: 34698550 PMCID: PMC8816638 DOI: 10.1152/physrev.00041.2020] [Citation(s) in RCA: 136] [Impact Index Per Article: 68.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 08/16/2021] [Accepted: 10/19/2021] [Indexed: 12/13/2022] Open
Abstract
The uptake of calcium into and extrusion of calcium from the mitochondrial matrix is a fundamental biological process that has critical effects on cellular metabolism, signaling, and survival. Disruption of mitochondrial calcium (mCa2+) cycling is implicated in numerous acquired diseases such as heart failure, stroke, neurodegeneration, diabetes, and cancer and is genetically linked to several inherited neuromuscular disorders. Understanding the mechanisms responsible for mCa2+ exchange therefore holds great promise for the treatment of these diseases. The past decade has seen the genetic identification of many of the key proteins that mediate mitochondrial calcium uptake and efflux. Here, we present an overview of the phenomenon of mCa2+ transport and a comprehensive examination of the molecular machinery that mediates calcium flux across the inner mitochondrial membrane: the mitochondrial uniporter complex (consisting of MCU, EMRE, MICU1, MICU2, MICU3, MCUB, and MCUR1), NCLX, LETM1, the mitochondrial ryanodine receptor, and the mitochondrial permeability transition pore. We then consider the physiological implications of mCa2+ flux and evaluate how alterations in mCa2+ homeostasis contribute to human disease. This review concludes by highlighting opportunities and challenges for therapeutic intervention in pathologies characterized by aberrant mCa2+ handling and by summarizing critical unanswered questions regarding the biology of mCa2+ flux.
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Affiliation(s)
- Joanne F Garbincius
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
| | - John W Elrod
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania
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25
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Dong Z, Yang X, Qiu T, an Y, Zhang G, Li Q, Jiang L, Yang G, Cao J, Sun X, Liu X, Liu D, Yao X. Exosomal miR-181a-2-3p derived from citreoviridin-treated hepatocytes activates hepatic stellate cells trough inducing mitochondrial calcium overload. Chem Biol Interact 2022; 358:109899. [DOI: 10.1016/j.cbi.2022.109899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 03/05/2022] [Accepted: 03/14/2022] [Indexed: 11/03/2022]
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26
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Lai HT, Canoy RJ, Campanella M, Vassetzky Y, Brenner C. Ca2+ Transportome and the Interorganelle Communication in Hepatocellular Carcinoma. Cells 2022; 11:cells11050815. [PMID: 35269437 PMCID: PMC8909868 DOI: 10.3390/cells11050815] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 12/24/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is a type of liver cancer with a poor prognosis for survival given the complications it bears on the patient. Though damages to the liver are acknowledged prodromic factors, the precise molecular aetiology remains ill-defined. However, many genes coding for proteins involved in calcium (Ca2+) homeostasis emerge as either mutated or deregulated. Ca2+ is a versatile signalling messenger that regulates functions that prime and drive oncogenesis, favouring metabolic reprogramming and gene expression. Ca2+ is present in cell compartments, between which it is trafficked through a network of transporters and exchangers, known as the Ca2+ transportome. The latter regulates and controls Ca2+ dynamics and tonicity. In HCC, the deregulation of the Ca2+ transportome contributes to tumorigenesis, the formation of metastasizing cells, and evasion of cell death. In this review, we reflect on these aspects by summarizing the current knowledge of the Ca2+ transportome and overviewing its composition in the plasma membrane, endoplasmic reticulum, and the mitochondria.
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Affiliation(s)
- Hong-Toan Lai
- CNRS, Institut Gustave Roussy, Aspects Métaboliques et Systémiques de l’Oncogénèse pour de Nouvelles Approches Thérapeutiques, Université Paris-Saclay, 94805 Villejuif, France; (H.-T.L.); (R.J.C.); (M.C.); (Y.V.)
| | - Reynand Jay Canoy
- CNRS, Institut Gustave Roussy, Aspects Métaboliques et Systémiques de l’Oncogénèse pour de Nouvelles Approches Thérapeutiques, Université Paris-Saclay, 94805 Villejuif, France; (H.-T.L.); (R.J.C.); (M.C.); (Y.V.)
- Institute of Human Genetics, National Institutes of Health, University of the Philippines, Manila 1000, Philippines
| | - Michelangelo Campanella
- CNRS, Institut Gustave Roussy, Aspects Métaboliques et Systémiques de l’Oncogénèse pour de Nouvelles Approches Thérapeutiques, Université Paris-Saclay, 94805 Villejuif, France; (H.-T.L.); (R.J.C.); (M.C.); (Y.V.)
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, London NW1 0TU, UK
- Consortium for Mitochondrial Research, University College London, London WC1 0TU, UK
- Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Yegor Vassetzky
- CNRS, Institut Gustave Roussy, Aspects Métaboliques et Systémiques de l’Oncogénèse pour de Nouvelles Approches Thérapeutiques, Université Paris-Saclay, 94805 Villejuif, France; (H.-T.L.); (R.J.C.); (M.C.); (Y.V.)
| | - Catherine Brenner
- CNRS, Institut Gustave Roussy, Aspects Métaboliques et Systémiques de l’Oncogénèse pour de Nouvelles Approches Thérapeutiques, Université Paris-Saclay, 94805 Villejuif, France; (H.-T.L.); (R.J.C.); (M.C.); (Y.V.)
- Correspondence:
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27
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The Splicing of the Mitochondrial Calcium Uniporter Genuine Activator MICU1 Is Driven by RBFOX2 Splicing Factor during Myogenic Differentiation. Int J Mol Sci 2022; 23:ijms23052517. [PMID: 35269658 PMCID: PMC8909990 DOI: 10.3390/ijms23052517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/17/2022] [Accepted: 02/22/2022] [Indexed: 02/04/2023] Open
Abstract
Alternative splicing, the process by which exons within a pre-mRNA transcript are differentially joined or skipped, is crucial in skeletal muscle since it is required both during myogenesis and in post-natal life to reprogram the transcripts of contractile proteins, metabolic enzymes, and transcription factors in functionally distinct muscle fiber types. The importance of such events is underlined by the numerosity of pathological conditions caused by alternative splicing aberrations. Importantly, many skeletal muscle Ca2+ homeostasis genes are also regulated by alternative splicing mechanisms, among which is the Mitochondrial Ca2+ Uniporter (MCU) genuine activator MICU1 which regulates MCU opening upon cell stimulation. We have previously shown that murine skeletal muscle MICU1 is subjected to alternative splicing, thereby generating a splice variant-which was named MICU1.1-that confers unique properties to the mitochondrial Ca2+ uptake and ensuring sufficient ATP production for muscle contraction. Here we extended the analysis of MICU1 alternative splicing to human tissues, finding two additional splicing variants that were characterized by their ability to regulate mitochondrial Ca2+ uptake. Furthermore, we found that MICU1 alternative splicing is induced during myogenesis by the splicing factor RBFOX2. These results highlight the complexity of the alternative splicing mechanisms in skeletal muscle and the regulation of mitochondrial Ca2+ among tissues.
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28
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Yanda MK, Tomar V, Cole R, Guggino WB, Cebotaru L. The Mitochondrial Ca 2+ import complex is altered in ADPKD. Cell Calcium 2022; 101:102501. [PMID: 34823104 PMCID: PMC8840832 DOI: 10.1016/j.ceca.2021.102501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 11/05/2021] [Accepted: 11/06/2021] [Indexed: 01/03/2023]
Abstract
Mutations in either of the polycystic kidney disease genes, PKD1 or PKD2, engender the growth of cysts, altering renal function. Cystic growth is supported by major changes in cellular metabolism, some of which involve the mitochondrion, a major storage site for Ca2+ and a key organelle in cellular Ca2+ signaling. The goal here was to understand the role of components of the mitochondrial Ca2+ uptake complex in PC1-mutant cells in autosomal dominant polycystic kidney disease (ADPKD). We found that the mitochondrial Ca2+ uniporter (MCU) and voltage-dependent anion channels 1& 3 (VDAC) were down-regulated in different mouse and cell models of ADPKD along with the Ca2+-dependent enzyme, pyruvate dehydrogenase phosphatase (PDHX). The release of Ca2+ from the endoplasmic reticulum, and Ca2+ uptake by the mitochondria were upregulated in PC1(polycystin)-null cells. We also observed an enhanced staining with MitoTracker Red CMXRos in PC1-null cultured cells than in PC1-containing cells and a substantially higher increase in response to ER Ca2+ release. Increased colocalization of the Ca2+ sensitive dye, rhodamine2, with MitoTracker Green suggested an increase Ca2+ entry into the mitochondria in PC1 null cells subsequent to Ca2+ release from the ER or from Ca2+ entry from the extracellular solution. These data clearly demonstrate abnormal release of Ca2+ by the ER and corresponding alterations in Ca2+ uptake by the mitochondria in PC1-null cells. Importantly, inhibiting mitochondrial Ca2+ uptake with the specific inhibitor Ru360 inhibited cyst growth and altered both apoptosis and cell proliferation. We further show that the decrease in mitochondrial proteins and abnormally high Ca2+ signaling can be reversed by application of the cystic fibrosis (CFTR) corrector, VX-809. We conclude that enhanced Ca2+ signaling and alterations in proteins association with the mitochondrial Ca2+ uptake complex are associated with malfunction of PC1. Finally, our results identify novel therapeutic targets for treating ADPKD.
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Affiliation(s)
- Murali K Yanda
- The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Vartika Tomar
- The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Robert Cole
- The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - William B Guggino
- The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Liudmila Cebotaru
- The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
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29
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Gottschalk B, Madreiter-Sokolowski CT, Graier WF. Cristae junction as a fundamental switchboard for mitochondrial ion signaling and bioenergetics. Cell Calcium 2022; 101:102517. [PMID: 34915234 DOI: 10.1016/j.ceca.2021.102517] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 12/08/2021] [Indexed: 12/31/2022]
Abstract
OPA1 and MICU1 are both involved in the regulation of mitochondrial Ca2+ uptake and the stabilization of the cristae junction, which separates the inner mitochondrial membrane into the interboundary membrane and the cristae membrane. In this mini-review, we focus on the synergetic control of OPA1 and MICU1 on the cristae junction that serves as a fundamental regulator of multiple mitochondrial functions. In particular, we point to the critical role of an adaptive cristae junction permeability in mitochondrial Ca2+ signaling, spatial H+ gradients and mitochondrial membrane potential, metabolic activity, and apoptosis. These characteristics bear on a distinct localization of the oxidative phosphorylation machinery, the FoF1-ATPase, and mitochondrial Ca2+uniporter (MCU) within sections of the inner mitochondrial membrane isolated by the cristae junction and regulated by proteins like OPA1 and MICU1. We specifically focus on the impact of MICU1-regulated cristae junction on the activity and distribution of MCU within the complex ultrastructure of mitochondria.
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Affiliation(s)
- Benjamin Gottschalk
- Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, Graz, 8010 Austria
| | - Corina T Madreiter-Sokolowski
- Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, Graz, 8010 Austria
| | - Wolfgang F Graier
- Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, Graz, 8010 Austria; BioTechMed, Graz.
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30
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Berezhnaya E, Hajnóczky G. How do MICUs gate the mitochondrial calcium uniporter? Cell Calcium 2021; 100:102497. [PMID: 34775300 DOI: 10.1016/j.ceca.2021.102497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 10/27/2021] [Accepted: 10/28/2021] [Indexed: 10/19/2022]
Affiliation(s)
- Elena Berezhnaya
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States.
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31
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Garg V, Suzuki J, Paranjpe I, Unsulangi T, Boyman L, Milescu LS, Lederer WJ, Kirichok Y. The mechanism of MICU-dependent gating of the mitochondrial Ca 2+uniporter. eLife 2021; 10:e69312. [PMID: 34463251 PMCID: PMC8437439 DOI: 10.7554/elife.69312] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 08/09/2021] [Indexed: 12/11/2022] Open
Abstract
Ca2+ entry into mitochondria is through the mitochondrial calcium uniporter complex (MCUcx), a Ca2+-selective channel composed of five subunit types. Two MCUcx subunits (MCU and EMRE) span the inner mitochondrial membrane, while three Ca2+-regulatory subunits (MICU1, MICU2, and MICU3) reside in the intermembrane space. Here, we provide rigorous analysis of Ca2+ and Na+ fluxes via MCUcx in intact isolated mitochondria to understand the function of MICU subunits. We also perform direct patch clamp recordings of macroscopic and single MCUcx currents to gain further mechanistic insights. This comprehensive analysis shows that the MCUcx pore, composed of the EMRE and MCU subunits, is not occluded nor plugged by MICUs during the absence or presence of extramitochondrial Ca2+ as has been widely reported. Instead, MICUs potentiate activity of MCUcx as extramitochondrial Ca2+ is elevated. MICUs achieve this by modifying the gating properties of MCUcx allowing it to spend more time in the open state.
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Affiliation(s)
- Vivek Garg
- Department of Physiology, University of California San FranciscoSan FranciscoUnited States
- Department of Physiology, University of MarylandBaltimoreUnited States
| | - Junji Suzuki
- Department of Physiology, University of California San FranciscoSan FranciscoUnited States
| | - Ishan Paranjpe
- Department of Physiology, University of California San FranciscoSan FranciscoUnited States
| | - Tiffany Unsulangi
- Department of Physiology, University of California San FranciscoSan FranciscoUnited States
| | - Liron Boyman
- Department of Physiology, University of MarylandBaltimoreUnited States
| | - Lorin S Milescu
- Department of Biology, University of MarylandCollege ParkUnited States
| | | | - Yuriy Kirichok
- Department of Physiology, University of California San FranciscoSan FranciscoUnited States
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32
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Structural characterization of the mitochondrial Ca 2+ uniporter provides insights into Ca 2+ uptake and regulation. iScience 2021; 24:102895. [PMID: 34401674 PMCID: PMC8353469 DOI: 10.1016/j.isci.2021.102895] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The mitochondrial uniporter is a Ca2+-selective ion-conducting channel in the inner mitochondrial membrane that is involved in various cellular processes. The components of this uniporter, including the pore-forming membrane subunit MCU and the modulatory subunits MCUb, EMRE, MICU1, and MICU2, have been identified in recent years. Previously, extensive studies revealed various aspects of uniporter activities and proposed multiple regulatory models of mitochondrial Ca2+ uptake. Recently, the individual auxiliary components of the uniporter and its holocomplex have been structurally characterized, providing the first insight into the component structures and their spatial relationship within the context of the uniporter. Here, we review recent uniporter structural studies in an attempt to establish an architectural framework, elucidating the mechanism that governs mitochondrial Ca2+ uptake and regulation, and to address some apparent controversies. This information could facilitate further characterization of mitochondrial Ca2+ permeation and a better understanding of uniporter-related disease conditions. The uniporter contains multiple subunits regulating various cellular processes Significant structural progresses have been made for the holo-complex of uniporter The holo-complex structures have inspired to propose several regulatory models
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33
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Wu R, Zuo W, Xu X, Bi L, Zhang C, Chen H, Liu H. MCU That Is Transcriptionally Regulated by Nrf2 Augments Malignant Biological Behaviors in Oral Squamous Cell Carcinoma Cells. BIOMED RESEARCH INTERNATIONAL 2021; 2021:6650791. [PMID: 34189138 PMCID: PMC8195654 DOI: 10.1155/2021/6650791] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 05/10/2021] [Indexed: 01/10/2023]
Abstract
OBJECTIVE To clarify the role and molecular mechanism of mitochondrial calcium uniporter (MCU) in the malignant biological behaviors of oral squamous cell carcinoma (OSCC) cells through clinical and cellular experiments. METHODS Immunohistochemistry and qRT-PCR techniques were used to observe the expression of MCU, nuclear factor erythroid 2-related factor 2 (Nrf2), mitochondrial calcium uptake 1 (MICU1), and MICU2 in OSCC and normal tissues. After treatment with si-MCU, spermine, and/or sh-Nrf2, malignant biological behaviors of OSCC cells including proliferation, migration, and apoptosis were detected by clone formation, migration, and mitochondrial membrane potential (MMP) assays. Furthermore, MCU, MICU1, MICU2, Nrf2, and other proteins related to malignant biological behaviors were examined using western blot, immunohistochemistry, and immunofluorescence assays. RESULTS MCU, Nrf2, and MICU1 were strongly expressed in OSCC as compared to normal tissues, while MICU2 was relatively weakly expressed in OSCC tissues. Knockdown of MCU distinctly weakened proliferation and migration and lowered MMP level in CAL 27 cells. Conversely, its activation reinforced migrated capacity and increased MMP level in CAL 27 cells, which was reversed after cotransfection with sh-Nrf2. After treatment with si-MCU or spermine, Nrf2 expression was not affected in CAL 27 cells. However, MCU expression was distinctly suppressed in CAL 27 cells transfected with sh-Nrf2. Furthermore, knockdown of Nrf2 significantly reversed the increase in expression of MICU1 and MICU2 induced by MCU activation in CAL 27 cells. CONCLUSION MCU, as a novel oncogene of OSCC, augments malignant biological behaviors of OSCC cells, which could be transcriptionally regulated by Nrf2.
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Affiliation(s)
- Ran Wu
- Department of Stomatology, North China University of Science and Technology Affiliated Hospital, Tangshan, 063000 Hebei, China
| | - Weiwen Zuo
- Department of Stomatology, Tangshan Vocational and Technical College, Tangshan, 063000 Hebei, China
| | - Xiaoliang Xu
- Department of Stomatology, The Second Hospital of Tangshan, Tangshan, 063000 Hebei, China
| | - Lei Bi
- Department of Stomatology, North China University of Science and Technology Affiliated Hospital, Tangshan, 063000 Hebei, China
| | - Chunguang Zhang
- Department of Stomatology, North China University of Science and Technology Affiliated Hospital, Tangshan, 063000 Hebei, China
| | - Hui Chen
- Department of Stomatology, North China University of Science and Technology Affiliated Hospital, Tangshan, 063000 Hebei, China
| | - Hui Liu
- Department of Stomatology, North China University of Science and Technology Affiliated Hospital, Tangshan, 063000 Hebei, China
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34
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Pallafacchina G, Zanin S, Rizzuto R. From the Identification to the Dissection of the Physiological Role of the Mitochondrial Calcium Uniporter: An Ongoing Story. Biomolecules 2021; 11:biom11060786. [PMID: 34071006 PMCID: PMC8224590 DOI: 10.3390/biom11060786] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 05/14/2021] [Accepted: 05/20/2021] [Indexed: 12/16/2022] Open
Abstract
The notion of mitochondria being involved in the decoding and shaping of intracellular Ca2+ signals has been circulating since the end of the 19th century. Despite that, the molecular identity of the channel that mediates Ca2+ ion transport into mitochondria remained elusive for several years. Only in the last decade, the genes and pathways responsible for the mitochondrial uptake of Ca2+ began to be cloned and characterized. The gene coding for the pore-forming unit of the mitochondrial channel was discovered exactly 10 years ago, and its product was called mitochondrial Ca2+ uniporter or MCU. Before that, only one of its regulators, the mitochondria Ca2+ uptake regulator 1, MICU1, has been described in 2010. However, in the following years, the scientific interest in mitochondrial Ca2+ signaling regulation and physiological role has increased. This shortly led to the identification of many of its components, to the description of their 3D structure, and the characterization of the uniporter contribution to tissue physiology and pathology. In this review, we will summarize the most relevant achievements in the history of mitochondrial Ca2+ studies, presenting a chronological overview of the most relevant and landmarking discoveries. Finally, we will explore the impact of mitochondrial Ca2+ signaling in the context of muscle physiology, highlighting the recent advances in understanding the role of the MCU complex in the control of muscle trophism and metabolism.
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Affiliation(s)
- Giorgia Pallafacchina
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
- Neuroscience Institute, Italian National Research Council (CNR), 35131 Padua, Italy
- Correspondence: (G.P.); (R.R.); Tel.: +39-049-827-6029 (G.P.); +39-049-827-3001 (R.R.)
| | - Sofia Zanin
- Department of Immunology, Infectiology and Haematology, Institut Necker-Enfants Malades (INEM), INSERM U1151-CNRS UMR 8253, 75015 Paris, France;
| | - Rosario Rizzuto
- Neuroscience Institute, Italian National Research Council (CNR), 35131 Padua, Italy
- Correspondence: (G.P.); (R.R.); Tel.: +39-049-827-6029 (G.P.); +39-049-827-3001 (R.R.)
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Datta S, Jaiswal M. Mitochondrial calcium at the synapse. Mitochondrion 2021; 59:135-153. [PMID: 33895346 DOI: 10.1016/j.mito.2021.04.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 03/28/2021] [Accepted: 04/13/2021] [Indexed: 12/15/2022]
Abstract
Mitochondria are dynamic organelles, which serve various purposes, including but not limited to the production of ATP and various metabolites, buffering ions, acting as a signaling hub, etc. In recent years, mitochondria are being seen as the central regulators of cellular growth, development, and death. Since neurons are highly specialized cells with a heavy metabolic demand, it is not surprising that neurons are one of the most mitochondria-rich cells in an animal. At synapses, mitochondrial function and dynamics is tightly regulated by synaptic calcium. Calcium influx during synaptic activity causes increased mitochondrial calcium influx leading to an increased ATP production as well as buffering of synaptic calcium. While increased ATP production is required during synaptic transmission, calcium buffering by mitochondria is crucial to prevent faulty neurotransmission and excitotoxicity. Interestingly, mitochondrial calcium also regulates the mobility of mitochondria within synapses causing mitochondria to halt at the synapse during synaptic transmission. In this review, we summarize the various roles of mitochondrial calcium at the synapse.
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Affiliation(s)
- Sayantan Datta
- Tata Institute of Fundamental Research, Hyderabad, India
| | - Manish Jaiswal
- Tata Institute of Fundamental Research, Hyderabad, India.
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Alevriadou BR, Patel A, Noble M, Ghosh S, Gohil VM, Stathopulos PB, Madesh M. Molecular nature and physiological role of the mitochondrial calcium uniporter channel. Am J Physiol Cell Physiol 2021; 320:C465-C482. [PMID: 33296287 PMCID: PMC8260355 DOI: 10.1152/ajpcell.00502.2020] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/23/2020] [Accepted: 11/23/2020] [Indexed: 02/07/2023]
Abstract
Calcium (Ca2+) signaling is critical for cell function and cell survival. Mitochondria play a major role in regulating the intracellular Ca2+ concentration ([Ca2+]i). Mitochondrial Ca2+ uptake is an important determinant of cell fate and governs respiration, mitophagy/autophagy, and the mitochondrial pathway of apoptosis. Mitochondrial Ca2+ uptake occurs via the mitochondrial Ca2+ uniporter (MCU) complex. This review summarizes the present knowledge on the function of MCU complex, regulation of MCU channel, and the role of MCU in Ca2+ homeostasis and human disease pathogenesis. The channel core consists of four MCU subunits and essential MCU regulators (EMRE). Regulatory proteins that interact with them include mitochondrial Ca2+ uptake 1/2 (MICU1/2), MCU dominant-negative β-subunit (MCUb), MCU regulator 1 (MCUR1), and solute carrier 25A23 (SLC25A23). In addition to these proteins, cardiolipin, a mitochondrial membrane-specific phospholipid, has been shown to interact with the channel core. The dynamic interplay between the core and regulatory proteins modulates MCU channel activity after sensing local changes in [Ca2+]i, reactive oxygen species, and other environmental factors. Here, we highlight the structural details of the human MCU heteromeric assemblies and their known roles in regulating mitochondrial Ca2+ homeostasis. MCU dysfunction has been shown to alter mitochondrial Ca2+ dynamics, in turn eliciting cell apoptosis. Changes in mitochondrial Ca2+ uptake have been implicated in pathological conditions affecting multiple organs, including the heart, skeletal muscle, and brain. However, our structural and functional knowledge of this vital protein complex remains incomplete, and understanding the precise role for MCU-mediated mitochondrial Ca2+ signaling in disease requires further research efforts.
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Affiliation(s)
- B Rita Alevriadou
- Department of Biomedical Engineering, Jacobs School of Medicine and Biomedical Sciences and School of Engineering and Applied Sciences, University at Buffalo-State University of New York, Buffalo, New York
| | - Akshar Patel
- Department of Biomedical Engineering, Jacobs School of Medicine and Biomedical Sciences and School of Engineering and Applied Sciences, University at Buffalo-State University of New York, Buffalo, New York
| | - Megan Noble
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Sagnika Ghosh
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Muniswamy Madesh
- Department of Medicine/Cardiology Division, Center for Precision Medicine, University of Texas Health San Antonio, San Antonio, Texas
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Tanwar J, Singh JB, Motiani RK. Molecular machinery regulating mitochondrial calcium levels: The nuts and bolts of mitochondrial calcium dynamics. Mitochondrion 2021; 57:9-22. [PMID: 33316420 PMCID: PMC7610953 DOI: 10.1016/j.mito.2020.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 11/18/2020] [Accepted: 12/03/2020] [Indexed: 02/06/2023]
Abstract
Mitochondria play vital role in regulating the cellular energetics and metabolism. Further, it is a signaling hub for cell survival and apoptotic pathways. One of the key determinants that calibrate both cellular energetics and survival functions is mitochondrial calcium (Ca2+) dynamics. Mitochondrial Ca2+ regulates three Ca2+-sensitive dehydrogenase enzymes involved in tricarboxylic acid cycle (TCA) cycle thereby directly controlling ATP synthesis. On the other hand, excessive Ca2+ concentration within the mitochondrial matrix elevates mitochondrial reactive oxygen species (mROS) levels and causes mitochondrial membrane depolarization. This leads to opening of the mitochondrial permeability transition pore (mPTP) and release of cytochrome c into cytosol eventually triggering apoptosis. Therefore, it is critical for cell to maintain mitochondrial Ca2+ concentration. Since cells can neither synthesize nor metabolize Ca2+, it is the dynamic interplay of Ca2+ handling proteins involved in mitochondrial Ca2+ influx and efflux that take the center stage. In this review we would discuss the key molecular machinery regulating mitochondrial Ca2+ concentration. We would focus on the channel complex involved in bringing Ca2+ into mitochondrial matrix i.e. Mitochondrial Ca2+ Uniporter (MCU) and its key regulators Mitochondrial Ca2+ Uptake proteins (MICU1, 2 and 3), MCU regulatory subunit b (MCUb), Essential MCU Regulator (EMRE) and Mitochondrial Ca2+ Uniporter Regulator 1 (MCUR1). Further, we would deliberate on major mitochondrial Ca2+ efflux proteins i.e. Mitochondrial Na+/Ca2+/Li+ exchanger (NCLX) and Leucine zipper EF hand-containing transmembrane1 (Letm1). Moreover, we would highlight the physiological functions of these proteins and discuss their relevance in human pathophysiology. Finally, we would highlight key outstanding questions in the field.
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Affiliation(s)
- Jyoti Tanwar
- CSIR-Institute of Genomics and Integrative Biology (IGIB), New Delhi 10025, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Jaya Bharti Singh
- Laboratory of Calciomics and Systemic Pathophysiology (LCSP), Regional Centre for Biotechnology (RCB), Faridabad, Delhi-NCR, India
| | - Rajender K Motiani
- Laboratory of Calciomics and Systemic Pathophysiology (LCSP), Regional Centre for Biotechnology (RCB), Faridabad, Delhi-NCR, India.
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Márta K, Hasan P, Rodríguez-Prados M, Paillard M, Hajnóczky G. Pharmacological inhibition of the mitochondrial Ca 2+ uniporter: Relevance for pathophysiology and human therapy. J Mol Cell Cardiol 2021; 151:135-144. [PMID: 33035551 PMCID: PMC7880870 DOI: 10.1016/j.yjmcc.2020.09.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 09/26/2020] [Accepted: 09/28/2020] [Indexed: 12/20/2022]
Abstract
Mitochondrial Ca2+ uptake has long been considered crucial for meeting the fluctuating energy demands of cells in the heart and other tissues. Increases in mitochondrial matrix [Ca2+] drive mitochondrial ATP production via stimulation of Ca2+-sensitive dehydrogenases. Mitochondria-targeted sensors have revealed mitochondrial matrix [Ca2+] rises that closely follow the cytoplasmic [Ca2+] signals in many paradigms. Mitochondrial Ca2+ uptake is mediated by the Ca2+ uniporter (mtCU). Pharmacological manipulation of the mtCU is potentially key to understanding its physiological significance, but no specific, cell-permeable inhibitors were identified. In the past decade, as the molecular identity of the mtCU was brought to light, efforts have focused on genetic targeting. However, in the cells/animals that are able to survive impaired mtCU function, robust compensatory changes were found in the mtCU as well as other mechanisms. Thus, the discovery, through chemical library screens on normal and mtCU-deficient cells, of new small-molecule inhibitors with improved cell permeability and specificity might offer a better chance to test the relevance of mitochondrial Ca2+ uptake. Success with the development of small molecule mtCU inhibitors is also expected to have clinical impact, considering the growing evidence for the role of mitochondrial Ca2+ uptake in a variety of diseases, including heart attack, stroke and various neurodegenerative disorders. Here, we review the progress in pharmacological targeting of mtCU and illustrate the challenges in this field using data obtained with MCU-i11, a new small molecule inhibitor.
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Affiliation(s)
- Katalin Márta
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Prottoy Hasan
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Macarena Rodríguez-Prados
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Melanie Paillard
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA; Univ-Lyon, CarMeN Laboratory, INSERM, INRA, Université Claude Bernard Lyon-1, INSA-Lyon, HCL, 69500 Bron, France
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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Ryan KC, Ashkavand Z, Norman KR. The Role of Mitochondrial Calcium Homeostasis in Alzheimer's and Related Diseases. Int J Mol Sci 2020; 21:ijms21239153. [PMID: 33271784 PMCID: PMC7730848 DOI: 10.3390/ijms21239153] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 11/23/2020] [Accepted: 11/26/2020] [Indexed: 02/06/2023] Open
Abstract
Calcium signaling is essential for neuronal function, and its dysregulation has been implicated across neurodegenerative diseases, including Alzheimer’s disease (AD). A close reciprocal relationship exists between calcium signaling and mitochondrial function. Growing evidence in a variety of AD models indicates that calcium dyshomeostasis drastically alters mitochondrial activity which, in turn, drives neurodegeneration. This review discusses the potential pathogenic mechanisms by which calcium impairs mitochondrial function in AD, focusing on the impact of calcium in endoplasmic reticulum (ER)–mitochondrial communication, mitochondrial transport, oxidative stress, and protein homeostasis. This review also summarizes recent data that highlight the need for exploring the mechanisms underlying calcium-mediated mitochondrial dysfunction while suggesting potential targets for modulating mitochondrial calcium levels to treat neurodegenerative diseases such as AD.
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Hou X, Outhwaite IR, Pedi L, Long SB. Cryo-EM structure of the calcium release-activated calcium channel Orai in an open conformation. eLife 2020; 9:62772. [PMID: 33252040 PMCID: PMC7723414 DOI: 10.7554/elife.62772] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 11/26/2020] [Indexed: 12/12/2022] Open
Abstract
The calcium release-activated calcium channel Orai regulates Ca2+ entry into non-excitable cells and is required for proper immune function. While the channel typically opens following Ca2+ release from the endoplasmic reticulum, certain pathologic mutations render the channel constitutively open. Previously, using one such mutation (H206A), we obtained low (6.7 Å) resolution X-ray structural information on Drosophila melanogaster Orai in an open conformation (Hou et al., 2018). Here we present a structure of this open conformation at 3.3 Å resolution using fiducial-assisted cryo-electron microscopy. The improved structure reveals the conformations of amino acids in the open pore, which dilates by outward movements of subunits. A ring of phenylalanine residues repositions to expose previously shielded glycine residues to the pore without significant rotational movement of the associated helices. Together with other hydrophobic amino acids, the phenylalanines act as the channel's gate. Structured M1-M2 turrets, not evident previously, form the channel's extracellular entrance.
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Affiliation(s)
- Xiaowei Hou
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Ian R Outhwaite
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Leanne Pedi
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Stephen Barstow Long
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
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41
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Feno S, Rizzuto R, Raffaello A, Vecellio Reane D. The molecular complexity of the Mitochondrial Calcium Uniporter. Cell Calcium 2020; 93:102322. [PMID: 33264708 DOI: 10.1016/j.ceca.2020.102322] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/19/2020] [Accepted: 11/19/2020] [Indexed: 12/20/2022]
Abstract
The role of mitochondria in regulating cellular Ca2+ homeostasis is crucial for the understanding of different cellular functions in physiological and pathological conditions. Nevertheless, the study of this aspect was severely limited by the lack of the molecular identity of the proteins responsible for mitochondrial Ca2+ uptake. In 2011, the discovery of the gene encoding for the Mitochondrial Calcium Uniporter (MCU), the selective channel responsible for mitochondrial Ca2+ uptake, gave rise to an explosion of studies aimed to characterize the composition, the regulation of the channel and its pathophysiological roles. Here, we summarize the recent discoveries on the molecular structure and composition of the MCU complex by providing new insights into the mechanisms that regulate MCU channel activity.
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Affiliation(s)
- Simona Feno
- Department of Biomedical Science, University of Padua, via G. Colombo 3, 35100 Padua, Italy
| | - Rosario Rizzuto
- Department of Biomedical Science, University of Padua, via G. Colombo 3, 35100 Padua, Italy
| | - Anna Raffaello
- Department of Biomedical Science, University of Padua, via G. Colombo 3, 35100 Padua, Italy; Myology Center, University of Padua, via G. Colombo 3, 35100 Padova, Italy.
| | - Denis Vecellio Reane
- Department of Biomedical Science, University of Padua, via G. Colombo 3, 35100 Padua, Italy.
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42
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Sligar SG, Denisov IG. Nanodiscs: A toolkit for membrane protein science. Protein Sci 2020; 30:297-315. [PMID: 33165998 DOI: 10.1002/pro.3994] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 10/30/2020] [Accepted: 10/30/2020] [Indexed: 12/25/2022]
Abstract
Membrane proteins are involved in numerous vital biological processes, including transport, signal transduction and the enzymes in a variety of metabolic pathways. Integral membrane proteins account for up to 30% of the human proteome and they make up more than half of all currently marketed therapeutic targets. Unfortunately, membrane proteins are inherently recalcitrant to study using the normal toolkit available to scientists, and one is most often left with the challenge of finding inhibitors, activators and specific antibodies using a denatured or detergent solubilized aggregate. The Nanodisc platform circumvents these challenges by providing a self-assembled system that renders typically insoluble, yet biologically and pharmacologically significant, targets such as receptors, transporters, enzymes, and viral antigens soluble in aqueous media in a native-like bilayer environment that maintain a target's functional activity. By providing a bilayer surface of defined composition and structure, Nanodiscs have found great utility in the study of cellular signaling complexes that assemble on a membrane surface. Nanodiscs provide a nanometer scale vehicle for the in vivo delivery of amphipathic drugs, therapeutic lipids, tethered nucleic acids, imaging agents and active protein complexes. This means for generating nanoscale lipid bilayers has spawned the successful use of numerous other polymer and peptide amphipathic systems. This review, in celebration of the Anfinsen Award, summarizes some recent results and provides an inroad into the current and historical literature.
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Affiliation(s)
- Stephen G Sligar
- Departments of Biochemistry Chemistry, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA
| | - Ilia G Denisov
- Departments of Biochemistry Chemistry, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA
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43
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Carvalho EJ, Stathopulos PB, Madesh M. Regulation of Ca 2+ exchanges and signaling in mitochondria. CURRENT OPINION IN PHYSIOLOGY 2020; 17:197-206. [PMID: 33103015 DOI: 10.1016/j.cophys.2020.08.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Mitochondrial calcium (mCa2+) homeostasis also plays a key role in the buffering of cytosolic calcium (cCa2+) and calcium transported into the mitochondrial matrix regulates cellular metabolism, migration and cell fate decisions. Recent work has highlighted the importance of mCa2+ homeostasis in regulating cellular function. The discovery of the mCa2+ uptake complex has shed new light on the role of mCa2+ dynamics in cytoskeletal remodeling, mitochondrial shape and motility in cellular dynamics. Here we attempt to decipher the vast landscape of calcium regulatory effects of the mitochondria, the underlying mechanisms and the dynamics that control cellular function.
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Affiliation(s)
- Edmund J Carvalho
- Department of Medicine, Centre for Precision Medicine, University of Texas Health San Antonio, San Antonio, TX, 78228.,Department of Microbiology, Centre for Cellular Immunotherapies, University of Pennsylvania, Pennsylvania, 19104
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Western University, London, ON N6A 5C1, Canada
| | - Muniswamy Madesh
- Department of Medicine, Centre for Precision Medicine, University of Texas Health San Antonio, San Antonio, TX, 78228
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Wang Y, Han Y, She J, Nguyen NX, Mootha VK, Bai XC, Jiang Y. Structural insights into the Ca 2+-dependent gating of the human mitochondrial calcium uniporter. eLife 2020; 9:e60513. [PMID: 32762847 PMCID: PMC7442490 DOI: 10.7554/elife.60513] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 08/06/2020] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial Ca2+ uptake is mediated by an inner mitochondrial membrane protein called the mitochondrial calcium uniporter. In humans, the uniporter functions as a holocomplex consisting of MCU, EMRE, MICU1 and MICU2, among which MCU and EMRE form a subcomplex and function as the conductive channel while MICU1 and MICU2 are EF-hand proteins that regulate the channel activity in a Ca2+-dependent manner. Here, we present the EM structures of the human mitochondrial calcium uniporter holocomplex (uniplex) in the presence and absence of Ca2+, revealing distinct Ca2+ dependent assembly of the uniplex. Our structural observations suggest that Ca2+ changes the dimerization interaction between MICU1 and MICU2, which in turn determines how the MICU1-MICU2 subcomplex interacts with the MCU-EMRE channel and, consequently, changes the distribution of the uniplex assemblies between the blocked and unblocked states.
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Affiliation(s)
- Yan Wang
- Department of Physiology, University of Texas Southwestern Medical CenterDallasUnited States
- Department of Biophysics, University of Texas Southwestern Medical CenterDallasUnited States
- Howard Hughes Medical Institute, University of Texas Southwestern Medical CenterDallasUnited States
| | - Yan Han
- Department of Physiology, University of Texas Southwestern Medical CenterDallasUnited States
- Department of Biophysics, University of Texas Southwestern Medical CenterDallasUnited States
- Howard Hughes Medical Institute, University of Texas Southwestern Medical CenterDallasUnited States
| | - Ji She
- Department of Physiology, University of Texas Southwestern Medical CenterDallasUnited States
- Department of Biophysics, University of Texas Southwestern Medical CenterDallasUnited States
| | - Nam X Nguyen
- Department of Physiology, University of Texas Southwestern Medical CenterDallasUnited States
- Department of Biophysics, University of Texas Southwestern Medical CenterDallasUnited States
- Howard Hughes Medical Institute, University of Texas Southwestern Medical CenterDallasUnited States
| | - Vamsi K Mootha
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Broad InstituteCambridgeUnited States
| | - Xiao-chen Bai
- Department of Biophysics, University of Texas Southwestern Medical CenterDallasUnited States
- Department of Cell Biology, University of Texas Southwestern Medical CenterDallasUnited States
| | - Youxing Jiang
- Department of Physiology, University of Texas Southwestern Medical CenterDallasUnited States
- Department of Biophysics, University of Texas Southwestern Medical CenterDallasUnited States
- Howard Hughes Medical Institute, University of Texas Southwestern Medical CenterDallasUnited States
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