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Fang X, Zhang Y, Wu H, Wang H, Miao R, Wei J, Zhang Y, Tian J, Tong X. Mitochondrial regulation of diabetic endothelial dysfunction: Pathophysiological links. Int J Biochem Cell Biol 2024; 170:106569. [PMID: 38556159 DOI: 10.1016/j.biocel.2024.106569] [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: 12/07/2023] [Revised: 03/27/2024] [Accepted: 03/27/2024] [Indexed: 04/02/2024]
Abstract
Micro- and macrovascular complications frequently occur in patients with diabetes, with endothelial dysfunction playing a key role in the development and progression of the complications. For the early diagnosis and optimal treatment of vascular complications associated with diabetes, it is imperative to comprehend the cellular and molecular mechanisms governing the function of diabetic endothelial cells. Mitochondria function as crucial sensors of environmental and cellular stress regulating endothelial cell viability, structural integrity and function. Impaired mitochondrial quality control mechanisms and mitochondrial dysfunction are the main features of endothelial damage. Hence, targeted mitochondrial therapy is considered promising novel therapeutic options in vascular complications of diabetes. In this review, we focus on the mitochondrial functions in the vascular endothelial cells and the pathophysiological role of mitochondria in diabetic endothelial dysfunction, aiming to provide a reference for related drug development and clinical diagnosis and treatment.
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Affiliation(s)
- Xinyi Fang
- Institute of Metabolic Diseases, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China; Graduate College, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Yanjiao Zhang
- Institute of Metabolic Diseases, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Haoran Wu
- Graduate College, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Han Wang
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Runyu Miao
- Institute of Metabolic Diseases, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China; Graduate College, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Jiahua Wei
- Graduate College, Changchun University of Chinese Medicine, Jilin 130117, China
| | - Yuxin Zhang
- Institute of Metabolic Diseases, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Jiaxing Tian
- Institute of Metabolic Diseases, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China.
| | - Xiaolin Tong
- Institute of Metabolic Diseases, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China.
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2
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Ramos VM, Serna JDC, Vilas-Boas EA, Cabral-Costa JV, Cunha FM, Kataura T, Korolchuk VI, Kowaltowski AJ. Mitochondrial sodium/calcium exchanger (NCLX) regulates basal and starvation-induced autophagy through calcium signaling. FASEB J 2024; 38:e23454. [PMID: 38315457 DOI: 10.1096/fj.202301368rr] [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: 07/06/2023] [Revised: 01/09/2024] [Accepted: 01/16/2024] [Indexed: 02/07/2024]
Abstract
Mitochondria shape intracellular Ca2+ signaling through the concerted activity of Ca2+ uptake via mitochondrial calcium uniporters and efflux by Na+ /Ca2+ exchangers (NCLX). Here, we describe a novel relationship among NCLX, intracellular Ca2+ , and autophagic activity. Conditions that stimulate autophagy in vivo and in vitro, such as caloric restriction and nutrient deprivation, upregulate NCLX expression in hepatic tissue and cells. Conversely, knockdown of NCLX impairs basal and starvation-induced autophagy. Similarly, acute inhibition of NCLX activity by CGP 37157 affects bulk and endoplasmic reticulum autophagy (ER-phagy) without significant impacts on mitophagy. Mechanistically, CGP 37157 inhibited the formation of FIP200 puncta and downstream autophagosome biogenesis. Inhibition of NCLX caused decreased cytosolic Ca2+ levels, and intracellular Ca2+ chelation similarly suppressed autophagy. Furthermore, chelation did not exhibit an additive effect on NCLX inhibition of autophagy, demonstrating that mitochondrial Ca2+ efflux regulates autophagy through the modulation of Ca2+ signaling. Collectively, our results show that the mitochondrial Ca2+ extrusion pathway through NCLX is an important regulatory node linking nutrient restriction and autophagy regulation.
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Affiliation(s)
- Vitor M Ramos
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Julian D C Serna
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Eloisa A Vilas-Boas
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | | | - Fernanda M Cunha
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Tetsushi Kataura
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Viktor I Korolchuk
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Alicia J Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
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3
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Rivera Nieves AM, Wauford BM, Fu A. Mitochondrial bioenergetics, metabolism, and beyond in pancreatic β-cells and diabetes. Front Mol Biosci 2024; 11:1354199. [PMID: 38404962 PMCID: PMC10884328 DOI: 10.3389/fmolb.2024.1354199] [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: 01/17/2024] [Indexed: 02/27/2024] Open
Abstract
In Type 1 and Type 2 diabetes, pancreatic β-cell survival and function are impaired. Additional etiologies of diabetes include dysfunction in insulin-sensing hepatic, muscle, and adipose tissues as well as immune cells. An important determinant of metabolic health across these various tissues is mitochondria function and structure. This review focuses on the role of mitochondria in diabetes pathogenesis, with a specific emphasis on pancreatic β-cells. These dynamic organelles are obligate for β-cell survival, function, replication, insulin production, and control over insulin release. Therefore, it is not surprising that mitochondria are severely defective in diabetic contexts. Mitochondrial dysfunction poses challenges to assess in cause-effect studies, prompting us to assemble and deliberate the evidence for mitochondria dysfunction as a cause or consequence of diabetes. Understanding the precise molecular mechanisms underlying mitochondrial dysfunction in diabetes and identifying therapeutic strategies to restore mitochondrial homeostasis and enhance β-cell function are active and expanding areas of research. In summary, this review examines the multidimensional role of mitochondria in diabetes, focusing on pancreatic β-cells and highlighting the significance of mitochondrial metabolism, bioenergetics, calcium, dynamics, and mitophagy in the pathophysiology of diabetes. We describe the effects of diabetes-related gluco/lipotoxic, oxidative and inflammation stress on β-cell mitochondria, as well as the role played by mitochondria on the pathologic outcomes of these stress paradigms. By examining these aspects, we provide updated insights and highlight areas where further research is required for a deeper molecular understanding of the role of mitochondria in β-cells and diabetes.
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Affiliation(s)
- Alejandra María Rivera Nieves
- Diabetes Center of Excellence, University of Massachusetts Chan Medical School, Worcester, MA, United States
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, United States
| | - Brian Michael Wauford
- Diabetes Center of Excellence, University of Massachusetts Chan Medical School, Worcester, MA, United States
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, United States
| | - Accalia Fu
- Diabetes Center of Excellence, University of Massachusetts Chan Medical School, Worcester, MA, United States
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, United States
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4
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Graff SM, Nakhe AY, Dadi PK, Dickerson MT, Dobson JR, Zaborska KE, Ibsen CE, Butterworth RB, Vierra NC, Jacobson DA. TALK-1-mediated alterations of β-cell mitochondrial function and insulin secretion impair glucose homeostasis on a diabetogenic diet. Cell Rep 2024; 43:113673. [PMID: 38206814 PMCID: PMC10961926 DOI: 10.1016/j.celrep.2024.113673] [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: 11/27/2022] [Revised: 11/08/2023] [Accepted: 01/01/2024] [Indexed: 01/13/2024] Open
Abstract
Mitochondrial Ca2+ ([Ca2+]m) homeostasis is critical for β-cell function and becomes disrupted during the pathogenesis of diabetes. [Ca2+]m uptake is dependent on elevations in cytoplasmic Ca2+ ([Ca2+]c) and endoplasmic reticulum Ca2+ ([Ca2+]ER) release, both of which are regulated by the two-pore domain K+ channel TALK-1. Here, utilizing a novel β-cell TALK-1-knockout (β-TALK-1-KO) mouse model, we found that TALK-1 limited β-cell [Ca2+]m accumulation and ATP production. However, following exposure to a high-fat diet (HFD), ATP-linked respiration, glucose-stimulated oxygen consumption rate, and glucose-stimulated insulin secretion (GSIS) were increased in control but not TALK1-KO mice. Although β-TALK-1-KO animals showed similar GSIS before and after HFD treatment, these mice were protected from HFD-induced glucose intolerance. Collectively, these data identify that TALK-1 channel control of β-cell function reduces [Ca2+]m and suggest that metabolic remodeling in diabetes drives dysglycemia.
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Affiliation(s)
- Sarah M Graff
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA; Department of Pharmacy and Pharmaceutical Sciences, Lipscomb University, Nashville, TN 37204, USA
| | - Arya Y Nakhe
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Jordyn R Dobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Karolina E Zaborska
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Chloe E Ibsen
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Regan B Butterworth
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Nicholas C Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
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Hui Y, Kuang L, Zhong Y, Tang Y, Xu Z, Zheng T. High glucose impairs cognitive function through inducing mitochondrial calcium overload in Treg cells. iScience 2024; 27:108689. [PMID: 38226157 PMCID: PMC10788441 DOI: 10.1016/j.isci.2023.108689] [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: 07/04/2023] [Revised: 11/02/2023] [Accepted: 12/05/2023] [Indexed: 01/17/2024] Open
Abstract
High glucose has been proved to impair cognitive function in type 2 diabetes, but the underlying mechanisms remain elusive. Here, we found that high glucose increased transcription factors' SP1 O-GlcNAcylation in regulatory T (Treg) cells. Glycosylated SP1 further enhanced HDAC2 recruitment and histone deacetylation on Na+/Ca2+/Li+ exchanger (NCLX) promoter, which downregulated NCLX expression and led to mitochondrial calcium overload and oxidative damage, thereby promoting Treg cell dysfunction, M1 microglia polarization, and diabetes-associated cognitive impairment. Importantly, GLP-1 receptor agonist alleviated these deleterious effects via GLP-1-receptor-mediated upregulation of OGA and inhibition of SP1 O-GlcNAcylation in Treg cells. Our study highlighted a link between high-glucose-mediated SP1 O-GlcNAcylation and HDAC2/NCLX signaling in control of mitochondrial calcium concentrations in Treg cells. It also revealed a mechanism for linking Treg cell dysfunction and cognitive impairment in type 2 diabetes and provides an insight into the mechanism underlying the neuroprotective effects of GLP-1 receptor agonist.
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Affiliation(s)
- Ya Hui
- Department of Endocrinology and Metabolism, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541199, P.R. China
- Guangxi Clinical Research Center for Diabetes and Metabolic Diseases, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541199, P.R. China
- Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin Medical University, Guilin, Guangxi 541199, P.R. China
| | - Liuyu Kuang
- Department of Endocrinology and Metabolism, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541199, P.R. China
- Guangxi Key Laboratory of Diabetic Systems Medicine, Guilin Medical University, Guilin, Guangxi 541199, P.R. China
| | - Yuanmei Zhong
- Department of Endocrinology and Metabolism, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541199, P.R. China
- Guangxi Key Laboratory of Metabolic Reprogramming and Intelligent Medical Engineering for Chronic Diseases, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541199, P.R. China
| | - Yunyun Tang
- Department of Endocrinology and Metabolism, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541199, P.R. China
- Guangxi Clinical Research Center for Diabetes and Metabolic Diseases, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541199, P.R. China
| | - Zhiqiang Xu
- Department of Endocrinology and Metabolism, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541199, P.R. China
| | - Tianpeng Zheng
- Department of Endocrinology and Metabolism, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541199, P.R. China
- Guangxi Clinical Research Center for Diabetes and Metabolic Diseases, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541199, P.R. China
- Guangxi Key Laboratory of Diabetic Systems Medicine, Guilin Medical University, Guilin, Guangxi 541199, P.R. China
- Guangxi Key Laboratory of Metabolic Reprogramming and Intelligent Medical Engineering for Chronic Diseases, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541199, P.R. China
- Guangxi Health Commission Key Laboratory of Glucose and Lipid Metabolism Disorders, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541199, P.R. China
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Mu-U-Min RBA, Diane A, Allouch A, Al-Siddiqi HH. Ca 2+-Mediated Signaling Pathways: A Promising Target for the Successful Generation of Mature and Functional Stem Cell-Derived Pancreatic Beta Cells In Vitro. Biomedicines 2023; 11:1577. [PMID: 37371672 DOI: 10.3390/biomedicines11061577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/18/2023] [Accepted: 05/23/2023] [Indexed: 06/29/2023] Open
Abstract
Diabetes mellitus is a chronic disease affecting over 500 million adults globally and is mainly categorized as type 1 diabetes mellitus (T1DM), where pancreatic beta cells are destroyed, and type 2 diabetes mellitus (T2DM), characterized by beta cell dysfunction. This review highlights the importance of the divalent cation calcium (Ca2+) and its associated signaling pathways in the proper functioning of beta cells and underlines the effects of Ca2+ dysfunction on beta cell function and its implications for the onset of diabetes. Great interest and promise are held by human pluripotent stem cell (hPSC) technology to generate functional pancreatic beta cells from diabetic patient-derived stem cells to replace the dysfunctional cells, thereby compensating for insulin deficiency and reducing the comorbidities of the disease and its associated financial and social burden on the patient and society. Beta-like cells generated by most current differentiation protocols have blunted functionality compared to their adult human counterparts. The Ca2+ dynamics in stem cell-derived beta-like cells and adult beta cells are summarized in this review, revealing the importance of proper Ca2+ homeostasis in beta-cell function. Consequently, the importance of targeting Ca2+ function in differentiation protocols is suggested to improve current strategies to use hPSCs to generate mature and functional beta-like cells with a comparable glucose-stimulated insulin secretion (GSIS) profile to adult beta cells.
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Affiliation(s)
- Razik Bin Abdul Mu-U-Min
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
| | - Abdoulaye Diane
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
| | - Asma Allouch
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
| | - Heba H Al-Siddiqi
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
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7
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Cabral-Costa JV, Vicente-Gutiérrez C, Agulla J, Lapresa R, Elrod JW, Almeida Á, Bolaños JP, Kowaltowski AJ. Mitochondrial sodium/calcium exchanger NCLX regulates glycolysis in astrocytes, impacting on cognitive performance. J Neurochem 2023; 165:521-535. [PMID: 36563047 PMCID: PMC10478152 DOI: 10.1111/jnc.15745] [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: 10/04/2022] [Revised: 12/11/2022] [Accepted: 12/12/2022] [Indexed: 12/24/2022]
Abstract
Intracellular Ca2+ concentrations are strictly controlled by plasma membrane transporters, the endoplasmic reticulum, and mitochondria, in which Ca2+ uptake is mediated by the mitochondrial calcium uniporter complex (MCUc), while efflux occurs mainly through the mitochondrial Na+ /Ca2+ exchanger (NCLX). RNAseq database repository searches led us to identify the Nclx transcript as highly enriched in astrocytes when compared with neurons. To assess the role of NCLX in mouse primary culture astrocytes, we inhibited its function both pharmacologically or genetically. This resulted in re-shaping of cytosolic Ca2+ signaling and a metabolic shift that increased glycolytic flux and lactate secretion in a Ca2+ -dependent manner. Interestingly, in vivo genetic deletion of NCLX in hippocampal astrocytes improved cognitive performance in behavioral tasks, whereas hippocampal neuron-specific deletion of NCLX impaired cognitive performance. These results unveil a role for NCLX as a novel modulator of astrocytic glucose metabolism, impacting on cognition.
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Affiliation(s)
- João Victor Cabral-Costa
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
| | - Carlos Vicente-Gutiérrez
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Centro de Investigación Biomédica en Red Sobre Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - Jesús Agulla
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - Rebeca Lapresa
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - John W. Elrod
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania, USA
| | - Ángeles Almeida
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - Juan P. Bolaños
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Centro de Investigación Biomédica en Red Sobre Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - Alicia J. Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
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8
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Mitochondrial Ca2+ handling as a cell signaling hub: lessons from astrocyte function. Essays Biochem 2023; 67:63-75. [PMID: 36636961 DOI: 10.1042/ebc20220094] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 12/16/2022] [Accepted: 12/22/2022] [Indexed: 01/14/2023]
Abstract
Astrocytes are a heterogenous population of macroglial cells spread throughout the central nervous system with diverse functions, expression signatures, and intricate morphologies. Their subcellular compartments contain a distinct range of mitochondria, with functional microdomains exhibiting widespread activities, such as controlling local metabolism and Ca2+ signaling. Ca2+ is an ion of utmost importance, both physiologically and pathologically, and participates in critical central nervous system processes, including synaptic plasticity, neuron-astrocyte integration, excitotoxicity, and mitochondrial physiology and metabolism. The mitochondrial Ca2+ handling system is formed by the mitochondrial Ca2+ uniporter complex (MCUc), which mediates Ca2+ influx, and the mitochondrial Na+/Ca2+ exchanger (NCLX), responsible for most mitochondrial Ca2+ efflux, as well as additional components, including the mitochondrial permeability transition pore (mtPTP). Over the last decades, mitochondrial Ca2+ handling has been shown to be key for brain homeostasis, acting centrally in physiopathological processes such as astrogliosis, astrocyte-neuron activity integration, energy metabolism control, and neurodegeneration. In this review, we discuss the current state of knowledge regarding the mitochondrial Ca2+ handling system molecular composition, highlighting its impact on astrocytic homeostasis.
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9
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CKII Control of Axonal Plasticity Is Mediated by Mitochondrial Ca 2+ via Mitochondrial NCLX. Cells 2022; 11:cells11243990. [PMID: 36552754 PMCID: PMC9777275 DOI: 10.3390/cells11243990] [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: 10/04/2022] [Revised: 11/11/2022] [Accepted: 11/22/2022] [Indexed: 12/14/2022] Open
Abstract
Mitochondrial Ca2+ efflux by NCLX is a critical rate-limiting step in mitochondria signaling. We previously showed that NCLX is phosphorylated at a putative Casein Kinase 2 (CKII) site, the serine 271 (S271). Here, we asked if NCLX is regulated by CKII and interrogated the physiological implications of this control. We found that CKII inhibitors down-regulated NCLX-dependent Ca2+ transport activity in SH-SY5Y neuronal cells and primary hippocampal neurons. Furthermore, we show that the CKII phosphomimetic mutants on NCLX inhibited (S271A) and constitutively activated (S271D) NCLX transport, respectively, rendering it insensitive to CKII inhibition. These phosphomimetic NCLX mutations also control the allosteric regulation of NCLX by mitochondrial membrane potential (ΔΨm). Since the omnipresent CKII is necessary for modulating the plasticity of the axon initial segment (AIS), we interrogated, in hippocampal neurons, if NCLX is required for this process. Similarly to WT neurons, NCLX-KO neurons can exhibit homeostatic plasticity following M-channel block. However, while WT neurons utilize a CKII-sensitive distal relocation of AIS Na+ and Kv7 channels to decrease their intrinsic excitability, we did not observe such translocation in NCLX-KO neurons. Thus, our results indicate that NCLX is regulated by CKII and is a crucial link between CKII signaling and fast neuronal plasticity.
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10
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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: 151] [Impact Index Per Article: 75.5] [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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11
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Pretorius M, Huang C. Beta-Cell Adaptation to Pregnancy - Role of Calcium Dynamics. Front Endocrinol (Lausanne) 2022; 13:853876. [PMID: 35399944 PMCID: PMC8990731 DOI: 10.3389/fendo.2022.853876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 02/21/2022] [Indexed: 11/17/2022] Open
Abstract
During pregnancy, the mother develops insulin resistance to shunt nutrients to the growing fetus. As a result, the maternal islets of Langerhans undergo several changes to increase insulin secretion in order to maintain glucose homeostasis and prevent the development of gestational diabetes. These changes include an increase in β-cell proliferation and β-cell mass, upregulation of insulin synthesis and insulin content, enhanced cell-to-cell communication, and a lowering of the glucose threshold for insulin secretion, all of which resulting in an increase in glucose-stimulated insulin secretion. Emerging data suggests that a change in intracellular calcium dynamics occurs in the β-cell during pregnancy as part of the adaptive process. Influx of calcium into β-cells is crucial in the regulation of glucose-stimulated insulin secretion. Calcium fluxes into and out of the cytosol, endoplasmic reticulum, and mitochondria are also important in controlling β-cell function and survival. Here, we review calcium dynamics in islets in response to pregnancy-induced changes in hormones and signaling molecules, and how these changes may enhance insulin secretion to stave off gestational diabetes.
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12
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Takeuchi A, Matsuoka S. Physiological and Pathophysiological Roles of Mitochondrial Na +-Ca 2+ Exchanger, NCLX, in Hearts. Biomolecules 2021; 11:biom11121876. [PMID: 34944520 PMCID: PMC8699148 DOI: 10.3390/biom11121876] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/10/2021] [Accepted: 12/10/2021] [Indexed: 12/21/2022] Open
Abstract
It has been over 10 years since SLC24A6/SLC8B1, coding the Na+/Ca2+/Li+ exchanger (NCLX), was identified as the gene responsible for mitochondrial Na+-Ca2+ exchange, a major Ca2+ efflux system in cardiac mitochondria. This molecular identification enabled us to determine structure–function relationships, as well as physiological/pathophysiological contributions, and our understandings have dramatically increased. In this review, we provide an overview of the recent achievements in relation to NCLX, focusing especially on its heart-specific characteristics, biophysical properties, and spatial distribution in cardiomyocytes, as well as in cardiac mitochondria. In addition, we discuss the roles of NCLX in cardiac functions under physiological and pathophysiological conditions—the generation of rhythmicity, the energy metabolism, the production of reactive oxygen species, and the opening of mitochondrial permeability transition pores.
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Affiliation(s)
- Ayako Takeuchi
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193, Japan;
- Life Science Innovation Center, University of Fukui, Fukui 910-1193, Japan
- Correspondence: ; Tel.: +81-776-61-8311
| | - Satoshi Matsuoka
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193, Japan;
- Life Science Innovation Center, University of Fukui, Fukui 910-1193, Japan
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13
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Takeda Y, Matsuoka S. Impact of mitochondria on local calcium release in murine sinoatrial nodal cells. J Mol Cell Cardiol 2021; 164:42-50. [PMID: 34826768 DOI: 10.1016/j.yjmcc.2021.11.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 11/04/2021] [Accepted: 11/14/2021] [Indexed: 02/07/2023]
Abstract
Roles of mitochondria in sinoatrial nodal cells (SANCs) have not been fully clarified. We have previously demonstrated that mitochondrial Ca2+ efflux through the Na+-Ca2+ exchanger, NCXm, modulates sarcoplasmic reticulum (SR) Ca2+ content and automaticity of HL-1 cardiomyocytes. In this study, we extended this line of investigation to clarify the spatial and functional association between mitochondria and local calcium release (LCR) from the SR in murine SANCs. High-speed two dimensional (2D) and confocal line-scan imaging of SANCs revealed that LCRs in the early phase of the Ca2+ transient cycle length (CL) appeared with a higher probability near mitochondria. Although LCR increased toward the late phase of CL, no significant difference was noted in the occurrence of late LCRs near and distant from mitochondria. LCRs, especially in the late phase of CL, induced temporal and spatial heterogeneity of the Ca2+ transient amplitude. Attenuating mitochondrial Ca2+ efflux using an NCXm inhibitor, CGP-37157 (1 μM), reduced the amplitude, duration and size of LCR. It also attenuated early LCR occurrence, and simultaneously prolonged LCR period and CL. Additionally, CGP-37157 reduced caffeine-induced Ca2+ transient. Therefore, the inhibitory effect on LCR was attributable to the reduction of the SR Ca2+ content through NCXm inhibition. No obvious off-target effects of 1 μM CGP-37157 were found on T- and L-type voltage-gated Ca2+ currents and hyperpolarization-activated inward current. Taken together, these results suggest that mitochondria are involved in LCR generation by modulating the SR Ca2+ content through NCXm-mediated Ca2+ efflux in murine SANCs.
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Affiliation(s)
- Yukari Takeda
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, Life Science Innovation Center, University of Fukui, Fukui 910-1193, Japan.
| | - Satoshi Matsuoka
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, Life Science Innovation Center, University of Fukui, Fukui 910-1193, Japan.
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14
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Devi RV, Raj D, Doble M. Lockdown of mitochondrial Ca 2+ extrusion and subsequent resveratrol treatment kill HeLa cells by Ca 2+ overload. Int J Biochem Cell Biol 2021; 139:106071. [PMID: 34428589 DOI: 10.1016/j.biocel.2021.106071] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 08/06/2021] [Accepted: 08/19/2021] [Indexed: 10/20/2022]
Abstract
Anticancer effect of resveratrol and the role of sodium/lithium/calcium exchanger in context with calcium ions are studied in human cervical cancer cell line. This therapeutic approach using siNCLX mediated gene silencing and drug therapy with resveratrol indicates the disruption of calcium homeostasis, increase in caspase (-3, 8, 9) mRNA expressions and DNA damage leading to apoptotic cell death. Monitoring the intracellular Ca2+ changes using fluo-4AM indicates highest rise in [Ca2+] level in sodium/lithium/calcium exchanger silenced group with five different stages, that is distinguishable based on the fluorescence intensity. In resveratrol treated and siNCLX + resveratrol treated groups no such cell staging differences were observed, despite uniform Ca2+ rise followed by decrease in the intensity. Integrating RNAi gene silencing of sodium/lithium/calcium exchanger with resveratrol can form the most interesting, efficient and promising therapeutic strategy in the treatment of cancer.
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Affiliation(s)
- R Viswambari Devi
- Bioengineering and Drug Design Laboratory, Department of Biotechnology, Indian Institute of Technology, Chennai, 600036, India
| | - Divakar Raj
- Bioengineering and Drug Design Laboratory, Department of Biotechnology, Indian Institute of Technology, Chennai, 600036, India
| | - Mukesh Doble
- Bioengineering and Drug Design Laboratory, Department of Biotechnology, Indian Institute of Technology, Chennai, 600036, India.
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15
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Rossetti G, Ermer JA, Stentenbach M, Siira SJ, Richman TR, Milenkovic D, Perks KL, Hughes LA, Jamieson E, Xiafukaiti G, Ward NC, Takahashi S, Gray N, Viola HM, Hool LC, Rackham O, Filipovska A. A common genetic variant of a mitochondrial RNA processing enzyme predisposes to insulin resistance. SCIENCE ADVANCES 2021; 7:eabi7514. [PMID: 34559558 PMCID: PMC8462889 DOI: 10.1126/sciadv.abi7514] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 08/04/2021] [Indexed: 05/31/2023]
Abstract
Mitochondrial energy metabolism plays an important role in the pathophysiology of insulin resistance. Recently, a missense N437S variant was identified in the MRPP3 gene, which encodes a mitochondrial RNA processing enzyme within the RNase P complex, with predicted impact on metabolism. We used CRISPR-Cas9 genome editing to introduce this variant into the mouse Mrpp3 gene and show that the variant causes insulin resistance on a high-fat diet. The variant did not influence mitochondrial gene expression markedly, but instead, it reduced mitochondrial calcium that lowered insulin release from the pancreatic islet β cells of the Mrpp3 variant mice. Reduced insulin secretion resulted in lower insulin levels that contributed to imbalanced metabolism and liver steatosis in the Mrpp3 variant mice on a high-fat diet. Our findings reveal that the MRPP3 variant may be a predisposing factor to insulin resistance and metabolic disease in the human population.
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Affiliation(s)
- Giulia Rossetti
- Harry Perkins Institute of Medical Research, Nedlands, Western Australia 6009, Australia
- ARC Centre of Excellence in Synthetic Biology, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Judith A. Ermer
- Harry Perkins Institute of Medical Research, Nedlands, Western Australia 6009, Australia
- ARC Centre of Excellence in Synthetic Biology, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Maike Stentenbach
- Harry Perkins Institute of Medical Research, Nedlands, Western Australia 6009, Australia
- ARC Centre of Excellence in Synthetic Biology, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Stefan J. Siira
- Harry Perkins Institute of Medical Research, Nedlands, Western Australia 6009, Australia
- ARC Centre of Excellence in Synthetic Biology, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Tara R. Richman
- Harry Perkins Institute of Medical Research, Nedlands, Western Australia 6009, Australia
- ARC Centre of Excellence in Synthetic Biology, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | | | - Kara L. Perks
- Harry Perkins Institute of Medical Research, Nedlands, Western Australia 6009, Australia
- ARC Centre of Excellence in Synthetic Biology, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Laetitia A. Hughes
- Harry Perkins Institute of Medical Research, Nedlands, Western Australia 6009, Australia
- ARC Centre of Excellence in Synthetic Biology, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Emma Jamieson
- Faculty of Health and Medical Sciences, Medical School, The Rural Clinical School of Western Australia, The University of Western Australia, Bunbury, Western Australia 6230, Australia
| | - Gulibaikelamu Xiafukaiti
- Department of Anatomy and Embryology, Faculty of Medicine, Laboratory Animal Resource Center (LARC), and Transborder Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
| | - Natalie C. Ward
- Dobney Hypertension Centre, Medical School, The University of Western Australia, Perth, Western Australia, Australia
| | - Satoru Takahashi
- Department of Anatomy and Embryology, Faculty of Medicine, Laboratory Animal Resource Center (LARC), and Transborder Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
| | - Nicola Gray
- Australian National Phenome Centre, Centre for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth, Western Australia 6150, Australia
| | - Helena M. Viola
- School of Human Sciences (Physiology), The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Livia C. Hool
- School of Human Sciences (Physiology), The University of Western Australia, Crawley, Western Australia 6009, Australia
- Victor Chang Cardiac Research Institute, Darlinghurst, Sydney, New South Wales 2010, Australia
| | - Oliver Rackham
- Harry Perkins Institute of Medical Research, Nedlands, Western Australia 6009, Australia
- ARC Centre of Excellence in Synthetic Biology, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Curtin Medical School, Curtin University, Bentley, Western Australia 6102, Australia
- Curtin Health Innovation Research Institute, Curtin University, Bentley, Western Australia 6102, Australia
- Telethon Kids Institute, Northern Entrance, Perth Children’s Hospital, 15 Hospital Avenue, Nedlands, Western Australia, Australia
| | - Aleksandra Filipovska
- Harry Perkins Institute of Medical Research, Nedlands, Western Australia 6009, Australia
- ARC Centre of Excellence in Synthetic Biology, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Telethon Kids Institute, Northern Entrance, Perth Children’s Hospital, 15 Hospital Avenue, Nedlands, Western Australia, Australia
- School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia 6009, Australia
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16
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Mitostasis, Calcium and Free Radicals in Health, Aging and Neurodegeneration. Biomolecules 2021; 11:biom11071012. [PMID: 34356637 PMCID: PMC8301949 DOI: 10.3390/biom11071012] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 07/06/2021] [Accepted: 07/07/2021] [Indexed: 12/18/2022] Open
Abstract
Mitochondria play key roles in ATP supply, calcium homeostasis, redox balance control and apoptosis, which in neurons are fundamental for neurotransmission and to allow synaptic plasticity. Their functional integrity is maintained by mitostasis, a process that involves mitochondrial transport, anchoring, fusion and fission processes regulated by different signaling pathways but mainly by the peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α). PGC-1α also favors Ca2+ homeostasis, reduces oxidative stress, modulates inflammatory processes and mobilizes mitochondria to where they are needed. To achieve their functions, mitochondria are tightly connected to the endoplasmic reticulum (ER) through specialized structures of the ER termed mitochondria-associated membranes (MAMs), which facilitate the communication between these two organelles mainly to aim Ca2+ buffering. Alterations in mitochondrial activity enhance reactive oxygen species (ROS) production, disturbing the physiological metabolism and causing cell damage. Furthermore, cytosolic Ca2+ overload results in an increase in mitochondrial Ca2+, resulting in mitochondrial dysfunction and the induction of mitochondrial permeability transition pore (mPTP) opening, leading to mitochondrial swelling and cell death through apoptosis as demonstrated in several neuropathologies. In summary, mitochondrial homeostasis is critical to maintain neuronal function; in fact, their regulation aims to improve neuronal viability and to protect against aging and neurodegenerative diseases.
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17
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Stavsky A, Stoler O, Kostic M, Katoshevsky T, Assali EA, Savic I, Amitai Y, Prokisch H, Leiz S, Daumer-Haas C, Fleidervish I, Perocchi F, Gitler D, Sekler I. Aberrant activity of mitochondrial NCLX is linked to impaired synaptic transmission and is associated with mental retardation. Commun Biol 2021; 4:666. [PMID: 34079053 PMCID: PMC8172942 DOI: 10.1038/s42003-021-02114-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 03/22/2021] [Indexed: 02/04/2023] Open
Abstract
Calcium dynamics control synaptic transmission. Calcium triggers synaptic vesicle fusion, determines release probability, modulates vesicle recycling, participates in long-term plasticity and regulates cellular metabolism. Mitochondria, the main source of cellular energy, serve as calcium signaling hubs. Mitochondrial calcium transients are primarily determined by the balance between calcium influx, mediated by the mitochondrial calcium uniporter (MCU), and calcium efflux through the sodium/lithium/calcium exchanger (NCLX). We identified a human recessive missense SLC8B1 variant that impairs NCLX activity and is associated with severe mental retardation. On this basis, we examined the effect of deleting NCLX in mice on mitochondrial and synaptic calcium homeostasis, synaptic activity, and plasticity. Neuronal mitochondria exhibited basal calcium overload, membrane depolarization, and a reduction in the amplitude and rate of calcium influx and efflux. We observed smaller cytoplasmic calcium transients in the presynaptic terminals of NCLX-KO neurons, leading to a lower probability of release and weaker transmission. In agreement, synaptic facilitation in NCLX-KO hippocampal slices was enhanced. Importantly, deletion of NCLX abolished long term potentiation of Schaffer collateral synapses. Our results show that NCLX controls presynaptic calcium transients that are crucial for defining synaptic strength as well as short- and long-term plasticity, key elements of learning and memory processes.
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Affiliation(s)
- Alexandra Stavsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ohad Stoler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Marko Kostic
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Tomer Katoshevsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Essam A Assali
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ivana Savic
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Yael Amitai
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Holger Prokisch
- Institute of Human Genetics, School of Medicine, Technische Universität München, Munich, Germany
- Institute of Neurogenomics, Helmholtz Zentrum München, Munich, Germany
| | - Steffen Leiz
- Department of Pediatrics, Klinikum Dritter Orden, Munich, Germany
| | | | - Ilya Fleidervish
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Fabiana Perocchi
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC), Helmholtz Zentrum München, Munich, Germany
- Munich Cluster for Systems Neurology, Munich, Germany
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
| | - Israel Sekler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
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18
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Assali EA, Sekler I. Sprinkling salt on mitochondria: The metabolic and pathophysiological roles of mitochondrial Na + signaling mediated by NCLX. Cell Calcium 2021; 97:102416. [PMID: 34062329 DOI: 10.1016/j.ceca.2021.102416] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/25/2021] [Accepted: 04/26/2021] [Indexed: 11/25/2022]
Abstract
NCLX, the mitochondrial Na+/Ca2+ transporter is a key player in Ca2+ signaling. However, its role in Na+ signaling is poorly understood. In this review we focus on Na+ signaling by NCLX, and discuss recent physiological and pathophysiological roles attributed to the Na+ influx into mitochondria.
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Affiliation(s)
- Essam A Assali
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, 84105, Israel
| | - Israel Sekler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, 84105, Israel.
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19
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Takeuchi A, Matsuoka S. Minor contribution of NCX to Na +-Ca 2+ exchange activity in brain mitochondria. Cell Calcium 2021; 96:102386. [PMID: 33706218 DOI: 10.1016/j.ceca.2021.102386] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 02/19/2021] [Accepted: 02/25/2021] [Indexed: 11/19/2022]
Abstract
NCLX was identified as a mitochondrial Na+-Ca2+ exchanger. However, contribution of NCLX to overall mitochondrial Na+-Ca2+ exchange activity remains unclear, especially in brain mitochondria where plasma membrane Na+-Ca2+ exchanger NCX also exists. We studied the issue using isolated mouse brain mitochondria. The Na+- as well as Li+-dependent Ca2+ efflux from mitochondria was significantly inhibited by a NCLX blocker, but was insensitive to NCX blockers, suggesting that NCLX comprises a major part in forward mode of mitochondrial Na+-Ca2+ exchange activity. On the other hand, the Na+-dependent Ca2+ influx into mitochondria, the reverse mode, was insensitive to all the blockers tested, suggesting unidentified Ca2+ transport systems.
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Affiliation(s)
- Ayako Takeuchi
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, and Life Science Innovation Center, University of Fukui, Fukui 910-1193, Japan.
| | - Satoshi Matsuoka
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, and Life Science Innovation Center, University of Fukui, Fukui 910-1193, Japan
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20
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Mitochondrial Calcium Signaling in Pancreatic β-Cell. Int J Mol Sci 2021; 22:ijms22052515. [PMID: 33802289 PMCID: PMC7959128 DOI: 10.3390/ijms22052515] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/22/2021] [Accepted: 02/26/2021] [Indexed: 12/13/2022] Open
Abstract
Accumulation of calcium in energized mitochondria of pancreatic β-cells is emerging as a crucial process for pancreatic β-cell function. β-cell mitochondria sense and shape calcium signals, linking the metabolism of glucose and other secretagogues to the generation of signals that promote insulin secretion during nutrient stimulation. Here, we describe the role of mitochondrial calcium signaling in pancreatic β-cell function. We report the latest pharmacological and genetic findings, including the first mitochondrial calcium-targeted intervention strategies developed to modulate pancreatic β-cell function and their potential relevance in the context of diabetes.
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21
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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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22
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Abstract
Hyperuricemia is associated with insulin resistance, pancreatic β-cell dysfunction and consequently with development of type 2 diabetes. Although a direct relationship between high levels of uric acid (UA) and the development of diabetes is still a controversial issue, there is some evidence that strongly points to pancreatic β-cells damage as a result of high serum UA levels. Here, the mechanisms underlying UA-induced β-cell damage are discussed. Available literature indicates that UA can decrease glucose-stimulated insulin secretion and cause β-cell death. The mechanisms underlying these effects are UA-induced oxidative stress and inflammation within the β-cells. UA also stimulates inducible nitric oxide (NO) synthase (iNOS) gene expression leading to NO-induced β-cell dysfunction. Thus hyperuricemia may potentially cause β-cell dysfunction, leading to diabetes. It may be hypothesized that in hyperuricemic subjects, UA-lowering drugs may be beneficial in preventing diabetes.
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Affiliation(s)
- Asghar Ghasemi
- Endocrine Physiology Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, P.O. Box: 19395-4763, No. 24, Parvaneh Street, Velenjak, Tehran, Iran.
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23
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Britti E, Delaspre F, Sanz-Alcázar A, Medina-Carbonero M, Llovera M, Purroy R, Mincheva-Tasheva S, Tamarit J, Ros J. Calcitriol increases frataxin levels and restores mitochondrial function in cell models of Friedreich Ataxia. Biochem J 2021; 478:1-20. [PMID: 33305808 DOI: 10.1042/bcj20200331] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 11/30/2020] [Accepted: 12/07/2020] [Indexed: 12/17/2023]
Abstract
Friedreich ataxia (FA) is a neurodegenerative disease caused by the deficiency of frataxin, a mitochondrial protein. In primary cultures of dorsal root ganglia neurons, we showed that frataxin depletion resulted in decreased levels of the mitochondrial calcium exchanger NCLX, neurite degeneration and apoptotic cell death. Here, we describe that frataxin-deficient dorsal root ganglia neurons display low levels of ferredoxin 1 (FDX1), a mitochondrial Fe/S cluster-containing protein that interacts with frataxin and, interestingly, is essential for the synthesis of calcitriol, the active form of vitamin D. We provide data that calcitriol supplementation, used at nanomolar concentrations, is able to reverse the molecular and cellular markers altered in DRG neurons. Calcitriol is able to recover both FDX1 and NCLX levels and restores mitochondrial membrane potential indicating an overall mitochondrial function improvement. Accordingly, reduction in apoptotic markers and neurite degeneration was observed and, as a result, cell survival was also recovered. All these beneficial effects would be explained by the finding that calcitriol is able to increase the mature frataxin levels in both, frataxin-deficient DRG neurons and cardiomyocytes; remarkably, this increase also occurs in lymphoblastoid cell lines derived from FA patients. In conclusion, these results provide molecular bases to consider calcitriol for an easy and affordable therapeutic approach for FA patients.
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Affiliation(s)
- Elena Britti
- Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, IRBLleida, AV. Rovira Roure 80, 25198 Lleida, Spain
| | - Fabien Delaspre
- Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, IRBLleida, AV. Rovira Roure 80, 25198 Lleida, Spain
| | - A Sanz-Alcázar
- Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, IRBLleida, AV. Rovira Roure 80, 25198 Lleida, Spain
| | - Marta Medina-Carbonero
- Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, IRBLleida, AV. Rovira Roure 80, 25198 Lleida, Spain
| | - Marta Llovera
- Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, IRBLleida, AV. Rovira Roure 80, 25198 Lleida, Spain
| | - Rosa Purroy
- Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, IRBLleida, AV. Rovira Roure 80, 25198 Lleida, Spain
| | - Stefka Mincheva-Tasheva
- Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, IRBLleida, AV. Rovira Roure 80, 25198 Lleida, Spain
| | - Jordi Tamarit
- Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, IRBLleida, AV. Rovira Roure 80, 25198 Lleida, Spain
| | - Joaquim Ros
- Dept. Ciències Mèdiques Bàsiques, Universitat de Lleida, IRBLleida, AV. Rovira Roure 80, 25198 Lleida, Spain
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Katoshevski T, Ben-Kasus Nissim T, Sekler I. Recent studies on NCLX in health and diseases. Cell Calcium 2021; 94:102345. [PMID: 33508514 DOI: 10.1016/j.ceca.2020.102345] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/29/2020] [Accepted: 12/29/2020] [Indexed: 12/27/2022]
Abstract
The mitochondria is a major hub for cellular Ca 2+ signaling. The identification of MCU, the mitochondrial Ca 2+ influx mediator, and the mitochondrial Ca 2+ extruder NCLX, were major breakthroughs in this field. Their identification provided novel molecular tools and animal models to interrogate their physiological function and mode of regulation. Here we will focus on the mitochondrial Na + / Ca 2+ exchanger NCLX that plays a dual role in mitochondrial Na + and Ca 2+ signaling. We will discuss recent advances in NCLX mods of regulation by kinases and mitochondrial ΔΨ. We will also focus on the heterogeneity of its expression in distinct mitochondrial populations and the pathophysiological implication of its excessive degradation. We will describe the ongoing debate on the stoichiometry of Na + to Ca 2+ transport, mediated by NCLX, and its physiological implication. We will focus on the major effects of mitochondrial Na + signaling by NCLX on mitochondrial metabolism in health; and finally, we will discuss the role NCLX plays in a wide range of health disorders, from heart failure and cancer to Parkinson and Alzheimer disease, making it a prime candidate for therapeutic targeting.
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Affiliation(s)
- Tomer Katoshevski
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel
| | - Tsipi Ben-Kasus Nissim
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel
| | - Israel Sekler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel.
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25
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Georgiadou E, Rutter GA. Control by Ca 2+ of mitochondrial structure and function in pancreatic β-cells. Cell Calcium 2020; 91:102282. [PMID: 32961506 PMCID: PMC7116533 DOI: 10.1016/j.ceca.2020.102282] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 08/25/2020] [Accepted: 08/25/2020] [Indexed: 12/11/2022]
Abstract
Mitochondria play a central role in glucose metabolism and the stimulation of insulin secretion from pancreatic β-cells. In this review, we discuss firstly the regulation and roles of mitochondrial Ca2+ transport in glucose-regulated insulin secretion, and the molecular machinery involved. Next, we discuss the evidence that mitochondrial dysfunction in β-cells is associated with type 2 diabetes, from a genetic, functional and structural point of view, and then the possibility that these changes may in part be mediated by dysregulation of cytosolic Ca2+. Finally, we review the importance of preserved mitochondrial structure and dynamics for mitochondrial gene expression and their possible relevance to the pathogenesis of type 2 diabetes.
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Affiliation(s)
- Eleni Georgiadou
- Section of Cell Biology and Functional Genomics, Department of Metabolism, Digestion and Reproduction, Imperial College London, du Cane Road, London, W12 0NN, UK
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Department of Metabolism, Digestion and Reproduction, Imperial College London, du Cane Road, London, W12 0NN, UK.
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26
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Aghelan Z, Kiani S, Nasiri A, Sadeghi M, Farrokhi A, Khodarahmi R. Factors Influencing Mitochondrial Function as a Key Mediator of Glucose-Induced Insulin Release: Highlighting Nicotinamide Nucleotide Transhydrogenase. INTERNATIONAL JOURNAL OF MOLECULAR AND CELLULAR MEDICINE 2020; 9:107-122. [PMID: 32934948 PMCID: PMC7489113 DOI: 10.22088/ijmcm.bums.9.2.107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 08/04/2020] [Indexed: 12/13/2022]
Abstract
Pancreatic β-cells recognize blood glucose changes and release insulin that is a peptide hormone responsible for stable glycemia. Diabetes, a chronic disorder of insulin insufficiency, leads to disturbed glucose homeostasis and multi-organ problems. Glucose and insulin are key markers in the follow-up and control of this disease. Mitochondrial metabolism of pancreatic beta cells is a crucial part of glucose-stimulated cascade of insulin secretion. Effective factors on β-cells mitochondrial function in production of compounds such as tricarboxylic acid intermediates, glutamate, nicotinamide adenine dinucleotide phosphate, and reactive oxygen species can have great effects on the secretion of insulin under diabetes. This review enhances our knowledge of factors influencing mitochondrial function as a key mediator of glucose-induced insulin release that accordingly will be helpful to further our understanding of the mechanisms implicated in the progressive beta cell failure that results in diabetes.
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Affiliation(s)
- Zahra Aghelan
- Department of Clinical Biochemistry, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Sara Kiani
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Abolfazl Nasiri
- Department of Clinical Biochemistry, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Masoud Sadeghi
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Alireza Farrokhi
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Reza Khodarahmi
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
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Knockout of PINK1 altered the neural connectivity of Drosophila dopamine PPM3 neurons at input and output sites. INVERTEBRATE NEUROSCIENCE 2020; 20:11. [PMID: 32766952 DOI: 10.1007/s10158-020-00244-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 07/09/2020] [Indexed: 12/19/2022]
Abstract
Impairment of the dopamine system is the main cause of Parkinson disease (PD). PTEN-induced kinase 1 (PINK1) is possibly involved in pathogenesis of PD. However, its role in dopaminergic neurons has not been fully established yet. In the present investigation, we have used the PINK1 knockout Drosophila model to explore the role of PINK1 in dopaminergic neurons. Electrophysiological and behavioral tests indicated that PINK1 elimination enhances the neural transmission from the presynaptic part of dopaminergic neurons in the protocerebral posterior medial region 3 (PPM3) to PPM3 neurons (which are homologous to those in the substantia nigra in humans). Firing properties of the action potential in PPM3 neurons were also altered in the PINK1 knockout genotypes. Abnormal motor ability was also observed in these PINK1 knockout animals. Our results indicate that knockout of PINK1 could alter both the input and output properties of PPM3 neurons.
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28
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Islam MM, Takeuchi A, Matsuoka S. Membrane current evoked by mitochondrial Na +-Ca 2+ exchange in mouse heart. J Physiol Sci 2020; 70:24. [PMID: 32354321 PMCID: PMC10717124 DOI: 10.1186/s12576-020-00752-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 04/24/2020] [Indexed: 01/19/2023]
Abstract
The electrogenicity of mitochondrial Na+-Ca2+ exchange (NCXm) had been controversial and no membrane current through it had been reported. We succeeded for the first time in recording NCXm-mediated currents using mitoplasts derived from mouse ventricle. Under conditions that K+, Cl-, and Ca2+ uniporter currents were inhibited, extra-mitochondrial Na+ induced inward currents with 1 μM Ca2+ in the pipette. The half-maximum concentration of Na+ was 35.6 mM. The inward current was diminished without Ca2+ in the pipette, and was augmented with 10 μM Ca2+. The Na+-induced inward currents were largely inhibited by CGP-37157, an NCXm blocker. However, the reverse mode of NCXm, which should be detected as an outward current, was hardly induced by extra-mitochondrial application of Ca2+ with Na+ in the pipette. It was concluded that NCXm is electrogenic. This property may be advantageous for facilitating Ca2+ extrusion from mitochondria, which has large negative membrane potential.
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Affiliation(s)
- Mohammed M Islam
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui, 910-1193, Japan
| | - Ayako Takeuchi
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui, 910-1193, Japan
- Life Science Innovation Center, University of Fukui, Fukui, 910-1193, Japan
| | - Satoshi Matsuoka
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui, 910-1193, Japan.
- Life Science Innovation Center, University of Fukui, Fukui, 910-1193, Japan.
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29
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Idevall-Hagren O, Tengholm A. Metabolic regulation of calcium signaling in beta cells. Semin Cell Dev Biol 2020; 103:20-30. [PMID: 32085965 DOI: 10.1016/j.semcdb.2020.01.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 01/10/2020] [Accepted: 01/28/2020] [Indexed: 12/22/2022]
Abstract
The cytoplasmic Ca2+ concentration ([Ca2+]cyt) regulates a vast number of cellular functions, including insulin secretion from beta cells. The major physiological insulin secretagogue, glucose, triggers [Ca2+]cyt oscillations in beta cells. Synchronization of the oscillations among the beta cells within an islet underlies the generation of pulsatile insulin secretion. This review describes the mechanisms generating [Ca2+]cyt oscillations, the interactions between [Ca2+]cyt and cell metabolism, as well as the contribution of various organelles to the shaping of [Ca2+]cyt signals and insulin secretion. It also discusses how Ca2+ signals are coordinated and spread throughout the islets and data indicating that altered Ca2+ signaling is associated with beta cell dysfunction and development of type 2 diabetes.
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Affiliation(s)
- Olof Idevall-Hagren
- Department of Medical Cell Biology, Uppsala University, Biomedical Centre, Box 571, SE-751 23 Uppsala, Sweden
| | - Anders Tengholm
- Department of Medical Cell Biology, Uppsala University, Biomedical Centre, Box 571, SE-751 23 Uppsala, Sweden.
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30
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Savic Azoulay I, Liu F, Hu Q, Rozenfeld M, Ben Kasus Nissim T, Zhu MX, Sekler I, Xu TL. ASIC1a channels regulate mitochondrial ion signaling and energy homeostasis in neurons. J Neurochem 2020; 153:203-215. [PMID: 31976561 DOI: 10.1111/jnc.14971] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 12/09/2019] [Accepted: 01/02/2020] [Indexed: 11/28/2022]
Abstract
Acid-sensing ion channel 1a (ASIC1a) is well-known to play a major pathophysiological role during brain ischemia linked to acute acidosis of ~pH 6, whereas its function during physiological brain activity, linked to much milder pH changes, is still poorly understood. Here, by performing live cell imaging utilizing Na+ and Ca2+ sensitive and spatially specific fluorescent dyes, we investigated the role of ASIC1a in cytosolic Na+ and Ca2+ signals elicited by a mild extracellular drop from pH 7.4 to 7.0 and how these affect mitochondrial Na+ and Ca2+ signaling or metabolic activity. We show that in mouse primary cortical neurons, this small extracellular pH change triggers cytosolic Na+ and Ca2+ waves that propagate to mitochondria. Inhibiting ASIC1a with Psalmotoxin 1 or ASIC1a gene knockout blocked not only the cytosolic but also the mitochondrial Na+ and Ca2+ signals. Moreover, physiological activation of ASIC1a by this pH shift enhances mitochondrial respiration and evokes mitochondrial Na+ signaling even in digitonin-permeabilized neurons. Altogether our results indicate that ASIC1a is critical in linking physiological extracellular pH stimuli to mitochondrial ion signaling and metabolic activity and thus is an important metabolic sensor.
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Affiliation(s)
- Ivana Savic Azoulay
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Fan Liu
- Department of Anatomy and Physiology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qin Hu
- Department of Anatomy and Physiology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Maya Rozenfeld
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Tsipi Ben Kasus Nissim
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, USA
| | - Israel Sekler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Tian-Le Xu
- Department of Anatomy and Physiology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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31
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Wu S, Lu Q, Ding Y, Wu Y, Qiu Y, Wang P, Mao X, Huang K, Xie Z, Zou MH. Hyperglycemia-Driven Inhibition of AMP-Activated Protein Kinase α2 Induces Diabetic Cardiomyopathy by Promoting Mitochondria-Associated Endoplasmic Reticulum Membranes In Vivo. Circulation 2020; 139:1913-1936. [PMID: 30646747 DOI: 10.1161/circulationaha.118.033552] [Citation(s) in RCA: 170] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Fundc1 (FUN14 domain containing 1), an outer mitochondrial membrane protein, is important for mitophagy and mitochondria-associated endoplasmic reticulum membranes (MAMs). The roles of Fundc1 and MAMs in diabetic hearts remain unknown. The aims of this study, therefore, were to determine whether the diabetes mellitus-induced Fundc1 expression could increase MAM formation, and whether disruption of MAM formation improves diabetic cardiac function. METHODS Levels of FUNDC1 were examined in the hearts from diabetic patients and nondiabetic donors. Levels of Fundc1-induced MAMs and mitochondrial and heart function were examined in mouse neonatal cardiomyocytes exposed to high glucose (HG, 30 mmol/L d-glucose for 48 hours), and in streptozotocin-treated cardiac-specific Fundc1 knockout mice and cardiac-specific Fundc1 knockout diabetic Akita mice, as well. RESULTS FUNDC1 levels were significantly elevated in cardiac tissues from diabetic patients in comparison with those from nondiabetic donors. In cultured mouse neonatal cardiomyocytes, HG conditions increased levels of Fundc1, the inositol 1,4,5-trisphosphate type 2 receptor (Ip3r2), and MAMs. Genetic downregulation of either Fundc1 or Ip3r2 inhibited MAM formation, reduced endoplasmic reticulum-mitochondrial Ca2+ flux, and improved mitochondrial function in HG-treated cardiomyocytes. Consistently, adenoviral overexpression of Fundc1 promoted MAM formation, mitochondrial Ca2+ increase, and mitochondrial dysfunction in cardiomyocytes exposed to normal glucose (5.5 mmol/L d-glucose). In comparison with nondiabetic controls, levels of Fundc1, Ip3r2, and MAMs were significantly increased in hearts from streptozotocin-treated mice and Akita mice. Furthermore, in comparison with control hearts, diabetes mellitus markedly increased coimmunoprecipitation of Fundc1 and Ip3r2. The binding of Fundc1 to Ip3r2 inhibits Ip3r2 ubiquitination and proteasome-mediated degradation. Cardiomyocyte-specific Fundc1 deletion ablated diabetes mellitus-induced MAM formation, prevented mitochondrial Ca2+ increase, mitochondrial fragmentation, and apoptosis with improved mitochondrial functional capacity and cardiac function. In mouse neonatal cardiomyocytes, HG suppressed AMP-activated protein kinase activity. Furthermore, in cardiomyocytes of Prkaa2 knockout mice, expression of Fundc1, MAM formation, and mitochondrial Ca2+ levels were significantly increased. Finally, adenoviral overexpression of a constitutively active mutant AMP-activated protein kinase ablated HG-induced MAM formation and mitochondrial dysfunction. CONCLUSIONS We conclude that diabetes mellitus suppresses AMP-activated protein kinase, initiating Fundc1-mediated MAM formation, mitochondrial dysfunction, and cardiomyopathy, suggesting that AMP-activated protein kinase-induced Fundc1 suppression is a valid target to treat diabetic cardiomyopathy.
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Affiliation(s)
- Shengnan Wu
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta (S.W., Q.L., Y.D., Y.W., Y.Q., Z.X., M.-H.Z.)
| | - Qiulun Lu
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta (S.W., Q.L., Y.D., Y.W., Y.Q., Z.X., M.-H.Z.)
| | - Ye Ding
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta (S.W., Q.L., Y.D., Y.W., Y.Q., Z.X., M.-H.Z.)
| | - Yin Wu
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta (S.W., Q.L., Y.D., Y.W., Y.Q., Z.X., M.-H.Z.)
| | - Yu Qiu
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta (S.W., Q.L., Y.D., Y.W., Y.Q., Z.X., M.-H.Z.)
| | - Pei Wang
- Mitochondria and Metabolism Center, University of Washington, Seattle (P.W.)
| | - Xiaoxiang Mao
- Wuhan Union Hospital, Huazhong University of Science and Technology, Hubei, China (Z.M., K.H.)
| | - Kai Huang
- Wuhan Union Hospital, Huazhong University of Science and Technology, Hubei, China (Z.M., K.H.)
| | - Zhonglin Xie
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta (S.W., Q.L., Y.D., Y.W., Y.Q., Z.X., M.-H.Z.)
| | - Ming-Hui Zou
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta (S.W., Q.L., Y.D., Y.W., Y.Q., Z.X., M.-H.Z.)
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Allosteric Regulation of NCLX by Mitochondrial Membrane Potential Links the Metabolic State and Ca 2+ Signaling in Mitochondria. Cell Rep 2019; 25:3465-3475.e4. [PMID: 30566870 DOI: 10.1016/j.celrep.2018.11.084] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 10/24/2018] [Accepted: 11/21/2018] [Indexed: 12/19/2022] Open
Abstract
Calcium is a key regulator of mitochondrial function under both normal and pathological conditions. The mechanisms linking metabolic activity to mitochondrial Ca2+ signaling remain elusive, however. Here, by monitoring mitochondrial Ca2+ transients while manipulating mitochondrial membrane potential (ΔΨm), we found that mild fluctuations in ΔΨm, which do not affect Ca2+ influx, are sufficient to strongly regulate NCLX, the major efflux pathway of Ca2+ from the mitochondria. Phosphorylation of NCLX or expression of phosphomimicking mutant (S258D) rescued NCLX activity from ΔΨm-driven allosteric inhibition. By screening ΔΨm sensitivity of NCLX mutants, we also identified amino acid residues that, through functional interaction with Ser258, control NCLX regulation. Finally, we find that glucose-driven ΔΨm changes in pancreatic β-cells control mitochondrial Ca2+ signaling primarily via NCLX regulation. Our results identify a feedback control between metabolic activity and mitochondrial Ca2+ signaling and the "safety valve" NCLX phosphorylation that can rescue Ca2+ efflux in depolarized mitochondria.
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Comparative Analysis of MicroRNA and mRNA Profiles of Sperm with Different Freeze Tolerance Capacities in Boar ( Sus scrofa) and Giant Panda ( Ailuropoda melanoleuca). Biomolecules 2019; 9:biom9090432. [PMID: 31480517 PMCID: PMC6769438 DOI: 10.3390/biom9090432] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 08/29/2019] [Accepted: 08/29/2019] [Indexed: 12/19/2022] Open
Abstract
Post-thawed sperm quality parameters vary across different species after cryopreservation. To date, the molecular mechanism of sperm cryoinjury, freeze-tolerance and other influential factors are largely unknown. In this study, significantly dysregulated microRNAs (miRNAs) and mRNAs in boar and giant panda sperm with different cryo-resistance capacity were evaluated. From the result of miRNA profile of fresh and frozen-thawed giant panda sperm, a total of 899 mature, novel miRNAs were identified, and 284 miRNAs were found to be significantly dysregulated (195 up-regulated and 89 down-regulated). Combined analysis of miRNA profiling of giant panda sperm and our previously published data on boar sperm, 46, 21 and 4 differentially expressed (DE) mRNAs in boar sperm were believed to be related to apoptosis, glycolysis and oxidative phosphorylation, respectively. Meanwhile, 87, 17 and 7 DE mRNAs in giant panda were associated with apoptosis, glycolysis and oxidative phosphorylation, respectively. Gene ontology (GO) analysis of the targets of DE miRNAs showed that they were mainly distributed on membrane related pathway in giant panda sperm, while cell components and cell processes were tied to the targets of DE miRNAs in boar sperm. Finally, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of DE mRNAs indicated that most of these DE mRNAs were distributed in membrane signal transduction-related pathways in giant panda sperm, while those in boar sperm were mainly distributed in the cytokine-cytokine receptor interaction pathway and inflammatory related pathways. In conclusion, although the different freezing extenders and programs were used, the DE miRNAs and mRNAs involved in apoptosis, energy metabolism, olfactory transduction pathway, inflammatory response and cytokine-cytokine interactions, could be the possible molecular mechanism of sperm cryoinjury and freeze tolerance.
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Functional properties and mode of regulation of the mitochondrial Na +/Ca 2+ exchanger, NCLX. Semin Cell Dev Biol 2019; 94:59-65. [PMID: 30658153 DOI: 10.1016/j.semcdb.2019.01.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 01/14/2019] [Accepted: 01/14/2019] [Indexed: 12/23/2022]
Abstract
Mitochondrial Ca2+ transient is the earliest discovered organellar Ca2+ signaling pathway. It consist of a Ca2+ influx, mediated by mitochondrial Ca2+ uniporter (MCU), and mitochondrial Ca2+ efflux mediated by a Na+/Ca2+ exchanger (NCLX). Mitochondrial Ca2+ signaling machinery plays a fundamental role in linking metabolic activity to cellular Ca2+ signaling, and in controlling local Ca2+ concertation in distinct cellular compartments. Impaired balance between mitochondrial Ca2+ influx and efflux leads to mitochondrial Ca2+ overload, an early and key event in ischemic or neurodegenerative syndromes. Molecular identification of NCLX and MCU happened only recently. Surprisingly, MCU knockout yielded a relatively mild phenotype while conditional knockout of NCLX led to a rapid fatal heart failure. Here we will focus on recent functional and molecular studies on NCLX structure and its mode of regulation. We will describe the unique crosstalk of this exchanger with Na+ and Ca2+ signaling pathways in the cell membrane and the endoplasmic reticulum, and with protein kinases that posttranslationally modulate NCLX activity. We will critically compare selectivity of pharmacological blockers versus molecular control of NCLX expression and activity. Finally we will discuss why this exchanger is essential for survival and can serve as an attractive therapeutic target.
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35
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Abstract
Mitochondrial Ca2+ regulation is crucial for bioenergetics and cellular signaling. The mechanisms controlling mitochondrial calcium homeostasis have been recently unraveled with the discovery of mitochondrial inner membrane proteins that regulate mitochondrial Ca2+ uptake and extrusion. Mitochondrial Ca2+ uptake depends on a large complex of proteins centered around the Ca2+ channel protein, mitochondrial Ca2+ uniporter (MCU) in close interactions with several regulatory subunits (MCUb, EMRE, MICU1, MICU2). Mitochondrial Ca2+ extrusion is mainly mediated by the mitochondrial Na+/Ca2+/Li+ exchanger (NCLX). Here, we review the major players of mitochondrial Ca2+ homeostasis and their physiological functions.
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Affiliation(s)
- Trayambak Pathak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Mohamed Trebak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, United States.
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36
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Function, regulation and physiological role of the mitochondrial Na + /Ca 2+ exchanger, NCLX. CURRENT OPINION IN PHYSIOLOGY 2018. [DOI: 10.1016/j.cophys.2018.02.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Mammucari C, Raffaello A, Vecellio Reane D, Gherardi G, De Mario A, Rizzuto R. Mitochondrial calcium uptake in organ physiology: from molecular mechanism to animal models. Pflugers Arch 2018. [PMID: 29541860 PMCID: PMC6060757 DOI: 10.1007/s00424-018-2123-2] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mitochondrial Ca2+ is involved in heterogeneous functions, ranging from the control of metabolism and ATP production to the regulation of cell death. In addition, mitochondrial Ca2+ uptake contributes to cytosolic [Ca2+] shaping thus impinging on specific Ca2+-dependent events. Mitochondrial Ca2+ concentration is controlled by influx and efflux pathways: the former controlled by the activity of the mitochondrial Ca2+ uniporter (MCU), the latter by the Na+/Ca2+ exchanger (NCLX) and the H+/Ca2+ (mHCX) exchanger. The molecular identities of MCU and of NCLX have been recently unraveled, thus allowing genetic studies on their physiopathological relevance. After a general framework on the significance of mitochondrial Ca2+ uptake, this review discusses the structure of the MCU complex and the regulation of its activity, the importance of mitochondrial Ca2+ signaling in different physiological settings, and the consequences of MCU modulation on organ physiology.
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Affiliation(s)
| | - Anna Raffaello
- Department of Biomedical Sciences, University of Padova, Padua, Italy
| | | | - Gaia Gherardi
- Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Agnese De Mario
- Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, Padua, Italy.
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Skelin Klemen M, Dolenšek J, Slak Rupnik M, Stožer A. The triggering pathway to insulin secretion: Functional similarities and differences between the human and the mouse β cells and their translational relevance. Islets 2017; 9:109-139. [PMID: 28662366 PMCID: PMC5710702 DOI: 10.1080/19382014.2017.1342022] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In β cells, stimulation by metabolic, hormonal, neuronal, and pharmacological factors is coupled to secretion of insulin through different intracellular signaling pathways. Our knowledge about the molecular machinery supporting these pathways and the patterns of signals it generates comes mostly from rodent models, especially the laboratory mouse. The increased availability of human islets for research during the last few decades has yielded new insights into the specifics in signaling pathways leading to insulin secretion in humans. In this review, we follow the most central triggering pathway to insulin secretion from its very beginning when glucose enters the β cell to the calcium oscillations it produces to trigger fusion of insulin containing granules with the plasma membrane. Along the way, we describe the crucial building blocks that contribute to the flow of information and focus on their functional role in mice and humans and on their translational implications.
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Affiliation(s)
- Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Marjan Slak Rupnik
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Institute of Physiology; Center for Physiology and Pharmacology; Medical University of Vienna; Vienna, Austria
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
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Optogenetic control of mitochondrial metabolism and Ca 2+ signaling by mitochondria-targeted opsins. Proc Natl Acad Sci U S A 2017; 114:E5167-E5176. [PMID: 28611221 DOI: 10.1073/pnas.1703623114] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Key mitochondrial functions such as ATP production, Ca2+ uptake and release, and substrate accumulation depend on the proton electrochemical gradient (ΔμH+) across the inner membrane. Although several drugs can modulate ΔμH+, their effects are hardly reversible, and lack cellular specificity and spatial resolution. Although channelrhodopsins are widely used to modulate the plasma membrane potential of excitable cells, mitochondria have thus far eluded optogenetic control. Here we describe a toolkit of optometabolic constructs based on selective targeting of channelrhodopsins with distinct functional properties to the inner mitochondrial membrane of intact cells. We show that our strategy enables a light-dependent control of the mitochondrial membrane potential (Δψm) and coupled mitochondrial functions such as ATP synthesis by oxidative phosphorylation, Ca2+ dynamics, and respiratory metabolism. By directly modulating Δψm, the mitochondria-targeted opsins were used to control complex physiological processes such as spontaneous beats in cardiac myocytes and glucose-dependent ATP increase in pancreatic β-cells. Furthermore, our optometabolic tools allow modulation of mitochondrial functions in single cells and defined cell regions.
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Ben-Kasus Nissim T, Zhang X, Elazar A, Roy S, Stolwijk JA, Zhou Y, Motiani RK, Gueguinou M, Hempel N, Hershfinkel M, Gill DL, Trebak M, Sekler I. Mitochondria control store-operated Ca 2+ entry through Na + and redox signals. EMBO J 2017; 36:797-815. [PMID: 28219928 DOI: 10.15252/embj.201592481] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 12/25/2016] [Accepted: 01/05/2017] [Indexed: 02/05/2023] Open
Abstract
Mitochondria exert important control over plasma membrane (PM) Orai1 channels mediating store-operated Ca2+ entry (SOCE). Although the sensing of endoplasmic reticulum (ER) Ca2+ stores by STIM proteins and coupling to Orai1 channels is well understood, how mitochondria communicate with Orai1 channels to regulate SOCE activation remains elusive. Here, we reveal that SOCE is accompanied by a rise in cytosolic Na+ that is critical in activating the mitochondrial Na+/Ca2+ exchanger (NCLX) causing enhanced mitochondrial Na+ uptake and Ca2+ efflux. Omission of extracellular Na+ prevents the cytosolic Na+ rise, inhibits NCLX activity, and impairs SOCE and Orai1 channel current. We show further that SOCE activates a mitochondrial redox transient which is dependent on NCLX and is required for preventing Orai1 inactivation through oxidation of a critical cysteine (Cys195) in the third transmembrane helix of Orai1. We show that mitochondrial targeting of catalase is sufficient to rescue redox transients, SOCE, and Orai1 currents in NCLX-deficient cells. Our findings identify a hitherto unknown NCLX-mediated pathway that coordinates Na+ and Ca2+ signals to effect mitochondrial redox control over SOCE.
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Affiliation(s)
- Tsipi Ben-Kasus Nissim
- The Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Xuexin Zhang
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Assaf Elazar
- The Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Soumitra Roy
- The Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Judith A Stolwijk
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Yandong Zhou
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Rajender K Motiani
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Maxime Gueguinou
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Nadine Hempel
- Department of Pharmacology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Michal Hershfinkel
- The Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Donald L Gill
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Mohamed Trebak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Israel Sekler
- The Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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Sharma V, Roy S, Sekler I, O'Halloran DM. The NCLX-type Na +/Ca 2+ Exchanger NCX-9 Is Required for Patterning of Neural Circuits in Caenorhabditis elegans. J Biol Chem 2017; 292:5364-5377. [PMID: 28196860 DOI: 10.1074/jbc.m116.758953] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 02/13/2017] [Indexed: 12/22/2022] Open
Abstract
NCLX is a Na+/Ca2+ exchanger that uses energy stored in the transmembrane sodium gradient to facilitate the exchange of sodium ions for ionic calcium. Mammals have a single NCLX, which has been shown to function primarily at the mitochondrion and is an important regulator of neuronal physiology by contributing to neurotransmission and synaptic plasticity. The role of NCLX in developmental cell patterning (e.g. in neural circuits) is largely unknown. Here we describe a novel role for the Caenorhabditis elegans NCLX-type protein, NCX-9, in neural circuit formation. NCX-9 functions in hypodermal seam cells that secrete the axon guidance cue UNC-129/BMP, and our data revealed that ncx-9-/- mutant animals exhibit development defects in stereotyped left/right axon guidance choices within the GABAergic motor neuron circuit. Our data also implicate NCX-9 in a LON-2/heparan sulfate and UNC-6/netrin-mediated, RAC-dependent signaling pathway to guide left/right patterning within this circuit. Finally, we also provide in vitro physiology data supporting the role for NCX-9 in handling calcium exchange at the mitochondrion. Taken together, our work reveals the specificity by which the handling by NCLX of calcium exchange can map to neural circuit patterning and axon guidance decisions during development.
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Affiliation(s)
- Vishal Sharma
- From the Department of Biological Sciences and.,the Institute for Neuroscience, George Washington University, Washington, D. C. 20052 and
| | - Soumitra Roy
- the Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8499000, Israel
| | - Israel Sekler
- the Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8499000, Israel
| | - Damien M O'Halloran
- From the Department of Biological Sciences and .,the Institute for Neuroscience, George Washington University, Washington, D. C. 20052 and
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Gerencser AA, Mookerjee SA, Jastroch M, Brand MD. Measurement of the Absolute Magnitude and Time Courses of Mitochondrial Membrane Potential in Primary and Clonal Pancreatic Beta-Cells. PLoS One 2016; 11:e0159199. [PMID: 27404273 PMCID: PMC4942067 DOI: 10.1371/journal.pone.0159199] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 06/28/2016] [Indexed: 12/22/2022] Open
Abstract
The aim of this study was to simplify, improve and validate quantitative measurement of the mitochondrial membrane potential (ΔψM) in pancreatic β-cells. This built on our previously introduced calculation of the absolute magnitude of ΔψM in intact cells, using time-lapse imaging of the non-quench mode fluorescence of tetramethylrhodamine methyl ester and a bis-oxonol plasma membrane potential (ΔψP) indicator. ΔψM is a central mediator of glucose-stimulated insulin secretion in pancreatic β-cells. ΔψM is at the crossroads of cellular energy production and demand, therefore precise assay of its magnitude is a valuable tool to study how these processes interplay in insulin secretion. Dispersed islet cell cultures allowed cell type-specific, single-cell observations of cell-to-cell heterogeneity of ΔψM and ΔψP. Glucose addition caused hyperpolarization of ΔψM and depolarization of ΔψP. The hyperpolarization was a monophasic step increase, even in cells where the ΔψP depolarization was biphasic. The biphasic response of ΔψP was associated with a larger hyperpolarization of ΔψM than the monophasic response. Analysis of the relationships between ΔψP and ΔψM revealed that primary dispersed β-cells responded to glucose heterogeneously, driven by variable activation of energy metabolism. Sensitivity analysis of the calibration was consistent with β-cells having substantial cell-to-cell variations in amounts of mitochondria, and this was predicted not to impair the accuracy of determinations of relative changes in ΔψM and ΔψP. Finally, we demonstrate a significant problem with using an alternative ΔψM probe, rhodamine 123. In glucose-stimulated and oligomycin-inhibited β-cells the principles of the rhodamine 123 assay were breached, resulting in misleading conclusions.
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Affiliation(s)
- Akos A. Gerencser
- Buck Institute for Research on Aging, Novato, California, United States of America
- Image Analyst Software, Novato, California, United States of America
| | - Shona A. Mookerjee
- Buck Institute for Research on Aging, Novato, California, United States of America
- Touro University California College of Pharmacy, Vallejo, California, United States of America
| | - Martin Jastroch
- Buck Institute for Research on Aging, Novato, California, United States of America
| | - Martin D. Brand
- Buck Institute for Research on Aging, Novato, California, United States of America
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Roles of the mitochondrial Na(+)-Ca(2+) exchanger, NCLX, in B lymphocyte chemotaxis. Sci Rep 2016; 6:28378. [PMID: 27328625 PMCID: PMC4916421 DOI: 10.1038/srep28378] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 06/03/2016] [Indexed: 12/21/2022] Open
Abstract
Lymphocyte chemotaxis plays important roles in immunological reactions, although the mechanism of its regulation is still unclear. We found that the cytosolic Na(+)-dependent mitochondrial Ca(2+) efflux transporter, NCLX, regulates B lymphocyte chemotaxis. Inhibiting or silencing NCLX in A20 and DT40 B lymphocytes markedly increased random migration and suppressed the chemotactic response to CXCL12. In contrast to control cells, cytosolic Ca(2+) was higher and was not increased further by CXCL12 in NCLX-knockdown A20 B lymphocytes. Chelating intracellular Ca(2+) with BAPTA-AM disturbed CXCL12-induced chemotaxis, suggesting that modulation of cytosolic Ca(2+) via NCLX, and thereby Rac1 activation and F-actin polymerization, is essential for B lymphocyte motility and chemotaxis. Mitochondrial polarization, which is necessary for directional movement, was unaltered in NCLX-knockdown cells, although CXCL12 application failed to induce enhancement of mitochondrial polarization, in contrast to control cells. Mouse spleen B lymphocytes were similar to the cell lines, in that pharmacological inhibition of NCLX by CGP-37157 diminished CXCL12-induced chemotaxis. Unexpectedly, spleen T lymphocyte chemotaxis was unaffected by CGP-37157 treatment, indicating that NCLX-mediated regulation of chemotaxis is B lymphocyte-specific, and mitochondria-endoplasmic reticulum Ca(2+) dynamics are more important in B lymphocytes than in T lymphocytes. We conclude that NCLX is pivotal for B lymphocyte motility and chemotaxis.
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PKA Phosphorylation of NCLX Reverses Mitochondrial Calcium Overload and Depolarization, Promoting Survival of PINK1-Deficient Dopaminergic Neurons. Cell Rep 2015; 13:376-86. [PMID: 26440884 PMCID: PMC4709126 DOI: 10.1016/j.celrep.2015.08.079] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 08/02/2015] [Accepted: 08/28/2015] [Indexed: 11/23/2022] Open
Abstract
Mitochondrial Ca(2+) overload is a critical, preceding event in neuronal damage encountered during neurodegenerative and ischemic insults. We found that loss of PTEN-induced putative kinase 1 (PINK1) function, implicated in Parkinson disease, inhibits the mitochondrial Na(+)/Ca(2+) exchanger (NCLX), leading to impaired mitochondrial Ca(2+) extrusion. NCLX activity was, however, fully rescued by activation of the protein kinase A (PKA) pathway. We further show that PKA rescues NCLX activity by phosphorylating serine 258, a putative regulatory NCLX site. Remarkably, a constitutively active phosphomimetic mutant of NCLX (NCLX(S258D)) prevents mitochondrial Ca(2+) overload and mitochondrial depolarization in PINK1 knockout neurons, thereby enhancing neuronal survival. Our results identify an mitochondrial Ca(2+) transport regulatory pathway that protects against mitochondrial Ca(2+) overload. Because mitochondrial Ca(2+) dyshomeostasis is a prominent feature of multiple disorders, the link between NCLX and PKA may offer a therapeutic target.
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Gerencser AA. Bioenergetic Analysis of Single Pancreatic β-Cells Indicates an Impaired Metabolic Signature in Type 2 Diabetic Subjects. Endocrinology 2015. [PMID: 26204464 DOI: 10.1210/en.2015-1552] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Impaired activation of mitochondrial energy metabolism by glucose has been demonstrated in type 2 diabetic β-cells. The cause of this dysfunction is unknown. The aim of this study was to identify segments of energy metabolism with normal or with altered function in human type 2 diabetes mellitus. The mitochondrial membrane potential (ΔψM), and its response to glucose, is the main driver of mitochondrial ATP synthesis and is hence a central mediator of glucose-induced insulin secretion, but its quantitative determination in β-cells from human donors has not been attempted, due to limitations in assay technology. Here, novel fluorescence microscopic assays are exploited to quantify ΔψM and its response to glucose and other secretagogues in β-cells of dispersed pancreatic islet cells from 4 normal and 3 type 2 diabetic organ donors. Mitochondrial volume densities and the magnitude of ΔψM in low glucose were not consistently altered in diabetic β-cells. However, ΔψM was consistently less responsive to elevation of glucose concentration, whereas the decreased response was not observed with metabolizable secretagogue mixtures that feed directly into the tricarboxylic acid cycle. Single-cell analysis of the heterogeneous responses to metabolizable secretagogues indicated no dysfunction in relaying ΔψM hyperpolarization to plasma membrane potential depolarization in diabetic β-cells. ΔψM of diabetic β-cells was distinctly responsive to acute inhibition of ATP synthesis during glucose stimulation. It is concluded that the mechanistic deficit in glucose-induced insulin secretion and mitochondrial hyperpolarization of diabetic human β-cells is located upstream of the tricarboxylic acid cycle and manifests in dampening the control of ΔψM by glucose metabolism.
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Affiliation(s)
- Akos A Gerencser
- Buck Institute for Research on Aging and Image Analyst Software, Novato, California 94945; and College of Pharmacy, Touro University California, Vallejo, California 94592
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Han YE, Ryu SY, Park SH, Lee KH, Lee SH, Ho WK. Ca(2+) clearance by plasmalemmal NCLX, Li(+)-permeable Na(+)/Ca(2+) exchanger, is required for the sustained exocytosis in rat insulinoma INS-1 cells. Pflugers Arch 2015; 467:2461-72. [PMID: 26100674 DOI: 10.1007/s00424-015-1715-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 06/03/2015] [Accepted: 06/11/2015] [Indexed: 11/29/2022]
Abstract
Na(+)/Ca(2+) exchangers are key players for Ca(2+) clearance in pancreatic β-cells, but their molecular determinants and roles in insulin secretion are not fully understood. In the present study, we newly discovered that the Li(+)-permeable Na(+)/Ca(2+) exchangers (NCLX), which were known as mitochondrial Na(+)/Ca(2+) exchangers, contributed to the Na(+)-dependent Ca(2+) movement across the plasma membrane in rat INS-1 insulinoma cells. Na(+)/Ca(2+) exchange activity by NCLX was comparable to that by the Na(+)/Ca(2+) exchanger, NCX. We also confirmed the presence of NCLX proteins on the plasma membrane using immunocytochemistry and cell surface biotinylation experiments. We further investigated the role of NCLX on exocytosis function by measuring the capacitance increase in response to repetitive depolarization. Small interfering (si)RNA-mediated downregulation of NCLX did not affect the initial exocytosis, but significantly suppressed sustained exocytosis and recovery of exocytosis. XIP (NCX inhibitory peptide) or Na(+) replacement for inhibiting Na(+)-dependent Ca(2+) clearance also selectively suppressed sustained exocytosis. Consistent with the idea that sustained exocytosis requires ATP-dependent vesicle recruitment, mitochondrial function, assessed by mitochondrial membrane potential (ΔΨ), was impaired by siNCLX or XIP. However, depolarization-induced exocytosis was hardly affected by changes in intracellular Na(+) concentration, suggesting a negligible contribution of mitochondrial Na(+)/Ca(2+) exchanger. Taken together, our data indicate that Na(+)/Ca(2+) exchanger-mediated Ca(2+) clearance mediated by NCLX and NCX is crucial for optimizing mitochondrial function, which in turn contributes to vesicle recruitment for sustained exocytosis in pancreatic β-cells.
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Affiliation(s)
- Young-Eun Han
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Shin-Young Ryu
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Sun-Hyun Park
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Kyu-Hee Lee
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Suk-Ho Lee
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Won-Kyung Ho
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea.
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The mitochondrial Na(+)/Ca(2+) exchanger may reduce high glucose-induced oxidative stress and nucleotide-binding oligomerization domain receptor 3 inflammasome activation in endothelial cells. JOURNAL OF GERIATRIC CARDIOLOGY : JGC 2015; 12:270-8. [PMID: 26089852 PMCID: PMC4460171 DOI: 10.11909/j.issn.1671-5411.2015.03.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 01/19/2015] [Accepted: 03/02/2015] [Indexed: 11/21/2022]
Abstract
Background The mitochondrial Na+/Ca2+ exchanger, NCLX, plays an important role in the balance between Ca2+ influx and efflux across the mitochondrial inner membrane in endothelial cells. Mitochondrial metabolism is likely to be affected by the activity of NCLX because Ca2+ activates several enzymes of the Krebs cycle. It is currently believed that mitochondria are not only centers of energy production but are also important sites of reactive oxygen species (ROS) generation and nucleotide-binding oligomerization domain receptor 3 (NLRP3) inflammasome activation. Methods & Results This study focused on NCLX function, in rat aortic endothelial cells (RAECs), induced by glucose. First, we detected an increase in NCLX expression in the endothelia of rats with diabetes mellitus, which was induced by an injection of streptozotocin. Next, colocalization of NCLX expression and mitochondria was detected using confocal analysis. Suppression of NCLX expression, using an siRNA construct (siNCLX), enhanced mitochondrial Ca2+ influx and blocked efflux induced by glucose. Unexpectedly, silencing of NCLX expression induced increased ROS generation and NLRP3 inflammasome activation. Conclusions These findings suggest that NCLX affects glucose-dependent mitochondrial Ca2+ signaling, thereby regulating ROS generation and NLRP3 inflammasome activation in high glucose conditions. In the early stages of high glucose stimulation, NCLX expression increases to compensate in order to self-protect mitochondrial maintenance, stability, and function in endothelial cells.
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Yang R, Lirussi D, Thornton TM, Jelley-Gibbs DM, Diehl SA, Case LK, Madesh M, Taatjes DJ, Teuscher C, Haynes L, Rincón M. Mitochondrial Ca²⁺ and membrane potential, an alternative pathway for Interleukin 6 to regulate CD4 cell effector function. eLife 2015; 4. [PMID: 25974216 PMCID: PMC4447996 DOI: 10.7554/elife.06376] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 05/13/2015] [Indexed: 12/25/2022] Open
Abstract
IL-6 plays an important role in determining the fate of effector CD4 cells and the cytokines that these cells produce. Here we identify a novel molecular mechanism by which IL-6 regulates CD4 cell effector function. We show that IL-6-dependent signal facilitates the formation of mitochondrial respiratory chain supercomplexes to sustain high mitochondrial membrane potential late during activation of CD4 cells. Mitochondrial hyperpolarization caused by IL-6 is uncoupled from the production of ATP by oxidative phosphorylation. However, it is a mechanism to raise the levels of mitochondrial Ca2+ late during activation of CD4 cells. Increased levels of mitochondrial Ca2+ in the presence of IL-6 are used to prolong Il4 and Il21 expression in effector CD4 cells. Thus, the effect of IL-6 on mitochondrial membrane potential and mitochondrial Ca2+ is an alternative pathway by which IL-6 regulates effector function of CD4 cells and it could contribute to the pathogenesis of inflammatory diseases. DOI:http://dx.doi.org/10.7554/eLife.06376.001 Inflammation is a normal part of the body's response to an infection or injury and it helps to start the healing process. However, if left unchecked, inflammation itself can damage tissues, and diseases such as rheumatoid arthritis are the result of uncontrolled inflammation. Certain immune cells release molecules that can either trigger or suppress inflammation. Interleukin 6 is an example of a ‘pro-inflammatory’ molecule, which regulates the activity of groups of immune cells collectively known as ‘CD4 cells’. People who are overweight or obese have higher levels of interleukin 6 than people of a healthy weight. Obesity and other metabolic conditions have been linked to problems with structures called mitochondria, which make a molecule called ATP that provides cells with the energy they need to survive. But it is not known if interleukin 6 can affect the activity of mitochondria inside CD4 cells. Now, Yang et al. have discovered that interleukin 6 can affect the mitochondria inside CD4 cells and, in doing so, have identified a new way that interleukin 6 can regulate these cells' activity. Experiments involving immune cells from mice revealed that interleukin 6 triggers a cascade of signaling events that aid the formation of so-called ‘mitochondrial respiratory chain supercomplexes’ in CD4 cells. These are groups of proteins that work together in the membranes of mitochondria and are vital for the activity of these structures. The formation of these supercomplexes maintains a large voltage difference across the membrane of the mitochondria that occurs during the later stages of CD4 cell activation. Yang et al. found that this voltage difference was not linked to the production of ATP, but that it did raise the levels of calcium ions inside the mitochondria. Further experiments revealed that these increased levels of calcium ions prolong the production of other pro-inflammatory molecules in the CD4 cells. Following the discovery of a new pathway that regulates the activity of CD4 cells, the next challenge is to see if the parts of this pathway could be targeted with drugs to help treat inflammatory diseases such as rheumatoid arthritis. Moreover, because interleukin 6 plays an active role in other diseases such as cancer, further studies of this new pathway may help explain how this molecule encourages cancers to progress and/or spread around the body. DOI:http://dx.doi.org/10.7554/eLife.06376.002
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Affiliation(s)
- Rui Yang
- Department of Medicine, Immunobiology Program, University of Vermont, Burlington, United States
| | - Dario Lirussi
- Department of Medicine, Immunobiology Program, University of Vermont, Burlington, United States
| | - Tina M Thornton
- Department of Medicine, Immunobiology Program, University of Vermont, Burlington, United States
| | | | - Sean A Diehl
- Department of Medicine, Immunobiology Program, University of Vermont, Burlington, United States
| | - Laure K Case
- Department of Medicine, Immunobiology Program, University of Vermont, Burlington, United States
| | - Muniswamy Madesh
- Department of Medical Genetics and Molecular Biochemistry, Temple University, Philadelphia, United States
| | - Douglas J Taatjes
- Department of Pathology and Laboratory Medicine, University of Vermont, Burlington, United States
| | - Cory Teuscher
- Department of Medicine, Immunobiology Program, University of Vermont, Burlington, United States
| | | | - Mercedes Rincón
- Department of Medicine, Immunobiology Program, University of Vermont, Burlington, United States
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49
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Life after the birth of the mitochondrial Na+/Ca2+ exchanger, NCLX. SCIENCE CHINA-LIFE SCIENCES 2015; 58:59-65. [DOI: 10.1007/s11427-014-4789-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 10/17/2014] [Indexed: 02/07/2023]
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50
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Quan X, Nguyen TT, Choi SK, Xu S, Das R, Cha SK, Kim N, Han J, Wiederkehr A, Wollheim CB, Park KS. Essential role of mitochondrial Ca2+ uniporter in the generation of mitochondrial pH gradient and metabolism-secretion coupling in insulin-releasing cells. J Biol Chem 2014; 290:4086-96. [PMID: 25548283 DOI: 10.1074/jbc.m114.632547] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
In pancreatic β-cells, ATP acts as a signaling molecule initiating plasma membrane electrical activity linked to Ca(2+) influx, which triggers insulin exocytosis. The mitochondrial Ca(2+) uniporter (MCU) mediates Ca(2+) uptake into the organelle, where energy metabolism is further stimulated for sustained second phase insulin secretion. Here, we have studied the contribution of the MCU to the regulation of oxidative phosphorylation and metabolism-secretion coupling in intact and permeabilized clonal β-cells as well as rat pancreatic islets. Knockdown of MCU with siRNA transfection blunted matrix Ca(2+) rises, decreased nutrient-stimulated ATP production as well as insulin secretion. Furthermore, MCU knockdown lowered the expression of respiratory chain complexes, mitochondrial metabolic activity, and oxygen consumption. The pH gradient formed across the inner mitochondrial membrane following nutrient stimulation was markedly lowered in MCU-silenced cells. In contrast, nutrient-induced hyperpolarization of the electrical gradient was not altered. In permeabilized cells, knockdown of MCU ablated matrix acidification in response to extramitochondrial Ca(2+). Suppression of the putative Ca(2+)/H(+) antiporter leucine zipper-EF hand-containing transmembrane protein 1 (LETM1) also abolished Ca(2+)-induced matrix acidification. These results demonstrate that MCU-mediated Ca(2+) uptake is essential to establish a nutrient-induced mitochondrial pH gradient which is critical for sustained ATP synthesis and metabolism-secretion coupling in insulin-releasing cells.
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Affiliation(s)
- Xianglan Quan
- From the Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Korea
| | - Tuyet Thi Nguyen
- From the Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Korea
| | - Seong-Kyung Choi
- From the Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Korea
| | - Shanhua Xu
- From the Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Korea
| | - Ranjan Das
- From the Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Korea
| | - Seung-Kuy Cha
- From the Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Korea
| | - Nari Kim
- Department of Physiology, College of Medicine, Inje University, Busan 614-735, Korea
| | - Jin Han
- Department of Physiology, College of Medicine, Inje University, Busan 614-735, Korea
| | | | - Claes B Wollheim
- Department of Cell Physiology and Metabolism, University of Geneva, 1211 Geneva 4, Switzerland
| | - Kyu-Sang Park
- From the Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Korea,
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