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Vilas-Boas EA, Kowaltowski AJ. Mitochondrial redox state, bioenergetics, and calcium transport in caloric restriction: A metabolic nexus. Free Radic Biol Med 2024; 219:195-214. [PMID: 38677486 DOI: 10.1016/j.freeradbiomed.2024.04.234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 04/22/2024] [Accepted: 04/24/2024] [Indexed: 04/29/2024]
Abstract
Mitochondria congregate central reactions in energy metabolism, many of which involve electron transfer. As such, they are expected to both respond to changes in nutrient supply and demand and also provide signals that integrate energy metabolism intracellularly. In this review, we discuss how mitochondrial bioenergetics and reactive oxygen species production is impacted by dietary interventions that change nutrient availability and impact on aging, such as calorie restriction. We also discuss how dietary interventions alter mitochondrial Ca2+ transport, regulating both mitochondrial and cytosolic processes modulated by this ion. Overall, a plethora of literature data support the idea that mitochondrial oxidants and calcium transport act as integrating signals coordinating the response to changes in nutritional supply and demand in cells, tissues, and animals.
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Affiliation(s)
- Eloisa A Vilas-Boas
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Brazil.
| | - Alicia J Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Brazil.
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2
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Turbitt J, Moffett RC, Brennan L, Johnson PRV, Flatt PR, McClenaghan NH, Tarasov AI. Molecular determinants and intracellular targets of taurine signalling in pancreatic islet β-cells. Acta Physiol (Oxf) 2024; 240:e14101. [PMID: 38243723 DOI: 10.1111/apha.14101] [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: 06/26/2023] [Revised: 12/26/2023] [Accepted: 01/08/2024] [Indexed: 01/21/2024]
Abstract
AIM Despite its abundance in pancreatic islets of Langerhans and proven antihyperglycemic effects, the impact of the essential amino acid, taurine, on islet β-cell biology has not yet received due consideration, which prompted the current studies exploring the molecular selectivity of taurine import into β-cells and its acute and chronic intracellular interactions. METHODS The molecular aspects of taurine transport were probed by exposing the clonal pancreatic BRIN BD11 β-cells and primary mouse and human islets to a range of the homologs of the amino acid (assayed at 2-20 mM), using the hormone release and imaging of intracellular signals as surrogate read-outs. Known secretagogues were employed to profile the interaction of taurine with acute and chronic intracellular signals. RESULTS Taurine transporter TauT was expressed in the islet β-cells, with the transport of taurine and homologs having a weak sulfonate specificity but significant sensitivity to the molecular weight of the transporter. Taurine, hypotaurine, homotaurine, and β-alanine enhanced insulin secretion in a glucose-dependent manner, an action potentiated by cytosolic Ca2+ and cAMP. Acute and chronic β-cell insulinotropic effects of taurine were highly sensitive to co-agonism with GLP-1, forskolin, tolbutamide, and membrane depolarization, with an unanticipated indifference to the activation of PKC and CCK8 receptors. Pre-culturing with GLP-1 or KATP channel inhibitors sensitized or, respectively, desensitized β-cells to the acute taurine stimulus. CONCLUSION Together, these data demonstrate the pathways whereby taurine exhibits a range of beneficial effects on insulin secretion and β-cell function, consistent with the antidiabetic potential of its dietary low-dose supplementation.
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Affiliation(s)
- Julie Turbitt
- School of Biomedical Sciences, Ulster University, Coleraine, UK
| | | | - Lorraine Brennan
- UCD Institute of Food and Health, UCD School of Agriculture and Food Science, University College Dublin, Dublin 4, Republic of Ireland
- UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin 4, Republic of Ireland
| | - Paul R V Johnson
- Nuffield Department of Surgical Sciences, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
- Oxford Biomedical Research Centre (OxBRC), Oxford, UK
| | - Peter R Flatt
- School of Biomedical Sciences, Ulster University, Coleraine, UK
| | - Neville H McClenaghan
- School of Biomedical Sciences, Ulster University, Coleraine, UK
- Department of Life Sciences, Atlantic Technological University, Sligo, Republic of Ireland
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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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Fletcher PA, Thompson B, Liu C, Bertram R, Satin LS, Sherman AS. Ca 2+ release or Ca 2+ entry, that is the question: what governs Ca 2+ oscillations in pancreatic β cells? Am J Physiol Endocrinol Metab 2023; 324:E477-E487. [PMID: 37074988 PMCID: PMC10228667 DOI: 10.1152/ajpendo.00030.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 04/06/2023] [Accepted: 04/07/2023] [Indexed: 04/20/2023]
Abstract
The standard model for Ca2+ oscillations in insulin-secreting pancreatic β cells centers on Ca2+ entry through voltage-activated Ca2+ channels. These work in combination with ATP-dependent K+ channels, which are the bridge between the metabolic state of the cells and plasma membrane potential. This partnership underlies the ability of the β cells to secrete insulin appropriately on a minute-to-minute time scale to control whole body plasma glucose. Though this model, developed over more than 40 years through many cycles of experimentation and mathematical modeling, has been very successful, it has been challenged by a hypothesis that calcium-induced calcium release from the endoplasmic reticulum through ryanodine or inositol trisphosphate (IP3) receptors is instead the key driver of islet oscillations. We show here that the alternative model is in fact incompatible with a large body of established experimental data and that the new observations offered in support of it can be better explained by the standard model.
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Affiliation(s)
- Patrick A Fletcher
- Laboratory of Biological Modeling, National Institutes of Health, Bethesda, Maryland, United States
| | - Ben Thompson
- Department of Pharmacology and Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Chanté Liu
- Department of Pharmacology and Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Richard Bertram
- Department of Mathematics and Programs in Neuroscience and Molecular Biophysics, Florida State University, Tallahassee, Florida, United States
| | - Leslie S Satin
- Department of Pharmacology and Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Arthur S Sherman
- Laboratory of Biological Modeling, National Institutes of Health, Bethesda, Maryland, United States
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6
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Synergistic mechanism between the endoplasmic reticulum and mitochondria and their crosstalk with other organelles. Cell Death Discov 2023; 9:51. [PMID: 36759598 PMCID: PMC9911404 DOI: 10.1038/s41420-023-01353-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 01/25/2023] [Accepted: 01/30/2023] [Indexed: 02/11/2023] Open
Abstract
Organelles are functional areas where eukaryotic cells perform processes necessary for life. Each organelle performs specific functions; however, highly coordinated crosstalk occurs between them. Disorder of organelle networks often occur in various diseases. The endoplasmic reticulum (ER) and mitochondria are crucial organelles in eukaryotic cells as they are the material synthesis and oxidative metabolism centers, respectively. Homeostasis and orchestrated interactions are essential for maintaining the normal activities of cells. However, the mode and mechanism of organelle crosstalk is still a research challenge. Furthermore, the intricate association between organelle dyshomeostasis and the progression of many human diseases remains unclear. This paper systematically summarized the latest research advances in the synergistic mechanism between the endoplasmic reticulum and mitochondria and their crosstalk with other organelles based on recent literature. It also highlights the application potential of organelle homeostasis maintenance as a preventative and treatment strategy for diseases.
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Sarnobat D, Moffett RC, Ma J, Flatt PR, McClenaghan NH, Tarasov AI. Taurine rescues pancreatic β-cell stress by stimulating α-cell transdifferentiation. Biofactors 2023. [PMID: 36714992 DOI: 10.1002/biof.1938] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 01/05/2023] [Indexed: 01/31/2023]
Abstract
The semi-essential ubiquitous amino acid taurine has been shown to alleviate obesity and hyperglycemia in humans; however, the pathways underlying the antidiabetic actions have not been characterized. We explored the effect of chronic taurine exposure on cell biology of pancreatic islets, in degenerative type 1-like diabetes. The latter was modeled by small dose of streptozotocin (STZ) injection for 5 days in mice, followed by a 10-day administration of taurine (2% w/v, orally) in the drinking water. Taurine treatment opposed the detrimental changes in islet morphology and β-/α-cell ratio, induced by STZ diabetes, coincidentally with a significant 3.9 ± 0.7-fold enhancement of proliferation and 40 ± 5% reduction of apoptosis in β-cells. In line with these findings, the treatment counteracted an upregulation of antioxidant (Sod1, Sod2, Cat, Gpx1) and downregulation of islet expansion (Ngn3, Itgb1) genes induced by STZ, in a pancreatic β-cell line. At the same time, taurine enhanced the transdifferentiation of α-cells into β-cells by 2.3 ± 0.8-fold, echoed in strong non-metabolic elevation of cytosolic Ca2+ levels in pancreatic α-cells. Our data suggest a bimodal effect of dietary taurine on islet β-cell biology, which combines the augmentation of α-/β-cell transdifferentiation with downregulation of apoptosis. The dualism of action, stemming presumably from the intra- and extracellular modality of the signal, is likely to explain the antidiabetic potential of taurine supplementation.
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Affiliation(s)
- Dipak Sarnobat
- School of Biomedical Sciences, Ulster University, Coleraine, UK
| | | | - Jinfang Ma
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Peter R Flatt
- School of Biomedical Sciences, Ulster University, Coleraine, UK
| | - Neville H McClenaghan
- School of Biomedical Sciences, Ulster University, Coleraine, UK
- Department of Life Sciences, Atlantic Technological University, Sligo, Ireland
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8
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Pan D, Xu L, Shi D, Guo M. Knowledge mapping of mitochondrial calcium uniporter from 2011 to 2022: A bibliometric analysis. Front Physiol 2023; 14:1107328. [PMID: 36744031 PMCID: PMC9895098 DOI: 10.3389/fphys.2023.1107328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 01/11/2023] [Indexed: 01/21/2023] Open
Abstract
Background: Calcium uptake research has a long history. However, the mitochondrial calcium uniporter (MCU) protein was first discovered in 2011. As investigations of mitochondrial calcium uniporter represent a new research hotspot, a comprehensive and objective perspective of the field is lacking. Hence, this bibliometric analysis aimed to provide the current study status and trends related to mitochondrial calcium uniporter research in the past decade. Methods: Articles were acquired from the Web of Science Core Collection database. We quantified and visualized information regarding annual publications, journals, cocited journals, countries/regions, institutions, authors, and cocited authors by using CiteSpace 5.8. R3 and VOSviewer. In addition, we analysed the citation and keyword bursts related to mitochondrial calcium uniporter studies. Results: From 2011 to 2022, 1,030 articles were published by 5,050 authors from 1,145 affiliations and 62 countries or regions. The country with the most published articles was the United States. The institution with the most published articles was the University of Padua. Rosario Rizzuto published the most articles and was also the most cocited author. Cell Calcium published the largest number of articles, whereas Journal of Biological Chemistry had the most cocitations. The top 5 keywords related to pathological processes were oxidative stress, cell death, permeability transition, apoptosis, and metabolism. MICU1, calcium, ryanodine receptor, ATP synthase and cyclophilin D were the top 5 keywords related to molecules. Conclusion: mitochondrial calcium uniporter research has grown stably over the last decade. Current studies focus on the structure of the mitochondrial calcium uniporter complex and its regulatory effect on mitochondrial calcium homeostasis. In addition, the potential role of mitochondrial calcium uniporter in different diseases has been explored. Current studies mostly involve investigations of cancer and neurodegenerative diseases. Our analysis provides guidance and new insights into further mitochondrial calcium uniporter research.
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Affiliation(s)
- Deng Pan
- Xiyuan Hospital of China Academy of Chinese Medical Sciences, Beijing, China,National Clinical Research Centre for Chinese Medicine Cardiology, Xiyuan Hospital of China Academy of Chinese Medical Sciences, Beijing, China,Graduate School of Beijing University of Chinese Medicine, Beijing, China
| | - Lin Xu
- Gynecological Department of Traditional Chinese Medicine, China-Japan Friendship Hospital, Beijing, China
| | - Dazhuo Shi
- Xiyuan Hospital of China Academy of Chinese Medical Sciences, Beijing, China,National Clinical Research Centre for Chinese Medicine Cardiology, Xiyuan Hospital of China Academy of Chinese Medical Sciences, Beijing, China,*Correspondence: Dazhuo Shi, ; Ming Guo,
| | - Ming Guo
- Xiyuan Hospital of China Academy of Chinese Medical Sciences, Beijing, China,National Clinical Research Centre for Chinese Medicine Cardiology, Xiyuan Hospital of China Academy of Chinese Medical Sciences, Beijing, China,*Correspondence: Dazhuo Shi, ; Ming Guo,
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Allen JG, Tessem JS. Ca 2+ Sensors Assemble: Function of the MCU Complex in the Pancreatic Beta Cell. Cells 2022; 11:cells11131993. [PMID: 35805078 PMCID: PMC9265474 DOI: 10.3390/cells11131993] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/17/2022] [Accepted: 06/20/2022] [Indexed: 12/05/2022] Open
Abstract
The Mitochondrial Calcium Uniporter Complex (MCU Complex) is essential for β-cell function due to its role in sustaining insulin secretion. The MCU complex regulates mitochondrial Ca2+ influx, which is necessary for increased ATP production following cellular glucose uptake, keeps the cell membrane K+ channels closed following initial insulin release, and ultimately results in sustained insulin granule exocytosis. Dysfunction in Ca2+ regulation results in an inability to sustain insulin secretion. This review defines the functions, structure, and mutations associated with the MCU complex members mitochondrial calcium uniporter protein (MCU), essential MCU regulator (EMRE), mitochondrial calcium uptake 1 (MICU1), mitochondrial calcium uptake 2 (MICU2), and mitochondrial calcium uptake 3 (MICU3) in the pancreatic β-cell. This review provides a framework for further evaluation of the MCU complex in β-cell function and insulin secretion.
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Ježek P, Holendová B, Jabůrek M, Dlasková A, Plecitá-Hlavatá L. Contribution of Mitochondria to Insulin Secretion by Various Secretagogues. Antioxid Redox Signal 2022; 36:920-952. [PMID: 34180254 PMCID: PMC9125579 DOI: 10.1089/ars.2021.0113] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Significance: Mitochondria determine glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells by elevating ATP synthesis. As the metabolic and redox hub, mitochondria provide numerous links to the plasma membrane channels, insulin granule vesicles (IGVs), cell redox, NADH, NADPH, and Ca2+ homeostasis, all affecting insulin secretion. Recent Advances: Mitochondrial redox signaling was implicated in several modes of insulin secretion (branched-chain ketoacid [BCKA]-, fatty acid [FA]-stimulated). Mitochondrial Ca2+ influx was found to enhance GSIS, reflecting cytosolic Ca2+ oscillations induced by action potential spikes (intermittent opening of voltage-dependent Ca2+ and K+ channels) or the superimposed Ca2+ release from the endoplasmic reticulum (ER). The ATPase inhibitory factor 1 (IF1) was reported to tune the glucose sensitivity range for GSIS. Mitochondrial protein kinase A was implicated in preventing the IF1-mediated inhibition of the ATP synthase. Critical Issues: It is unknown how the redox signal spreads up to the plasma membrane and what its targets are, what the differences in metabolic, redox, NADH/NADPH, and Ca2+ signaling, and homeostasis are between the first and second GSIS phase, and whether mitochondria can replace ER in the amplification of IGV exocytosis. Future Directions: Metabolomics studies performed to distinguish between the mitochondrial matrix and cytosolic metabolites will elucidate further details. Identifying the targets of cell signaling into mitochondria and of mitochondrial retrograde metabolic and redox signals to the cell will uncover further molecular mechanisms for insulin secretion stimulated by glucose, BCKAs, and FAs, and the amplification of secretion by glucagon-like peptide (GLP-1) and metabotropic receptors. They will identify the distinction between the hub β-cells and their followers in intact and diabetic states. Antioxid. Redox Signal. 36, 920-952.
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Affiliation(s)
- Petr Ježek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Blanka Holendová
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Martin Jabůrek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Andrea Dlasková
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Lydie Plecitá-Hlavatá
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
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Stožer A, Šterk M, Paradiž Leitgeb E, Markovič R, Skelin Klemen M, Ellis CE, Križančić Bombek L, Dolenšek J, MacDonald PE, Gosak M. From Isles of Königsberg to Islets of Langerhans: Examining the Function of the Endocrine Pancreas Through Network Science. Front Endocrinol (Lausanne) 2022; 13:922640. [PMID: 35784543 PMCID: PMC9240343 DOI: 10.3389/fendo.2022.922640] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 05/16/2022] [Indexed: 12/12/2022] Open
Abstract
Islets of Langerhans are multicellular microorgans located in the pancreas that play a central role in whole-body energy homeostasis. Through secretion of insulin and other hormones they regulate postprandial storage and interprandial usage of energy-rich nutrients. In these clusters of hormone-secreting endocrine cells, intricate cell-cell communication is essential for proper function. Electrical coupling between the insulin-secreting beta cells through gap junctions composed of connexin36 is particularly important, as it provides the required, most important, basis for coordinated responses of the beta cell population. The increasing evidence that gap-junctional communication and its modulation are vital to well-regulated secretion of insulin has stimulated immense interest in how subpopulations of heterogeneous beta cells are functionally arranged throughout the islets and how they mediate intercellular signals. In the last decade, several novel techniques have been proposed to assess cooperation between cells in islets, including the prosperous combination of multicellular imaging and network science. In the present contribution, we review recent advances related to the application of complex network approaches to uncover the functional connectivity patterns among cells within the islets. We first provide an accessible introduction to the basic principles of network theory, enumerating the measures characterizing the intercellular interactions and quantifying the functional integration and segregation of a multicellular system. Then we describe methodological approaches to construct functional beta cell networks, point out possible pitfalls, and specify the functional implications of beta cell network examinations. We continue by highlighting the recent findings obtained through advanced multicellular imaging techniques supported by network-based analyses, giving special emphasis to the current developments in both mouse and human islets, as well as outlining challenges offered by the multilayer network formalism in exploring the collective activity of islet cell populations. Finally, we emphasize that the combination of these imaging techniques and network-based analyses does not only represent an innovative concept that can be used to describe and interpret the physiology of islets, but also provides fertile ground for delineating normal from pathological function and for quantifying the changes in islet communication networks associated with the development of diabetes mellitus.
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Affiliation(s)
- Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Marko Šterk
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Eva Paradiž Leitgeb
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Rene Markovič
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Institute of Mathematics and Physics, Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
| | - Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Cara E. Ellis
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | | | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Patrick E. MacDonald
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- *Correspondence: Marko Gosak,
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12
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Abstract
The uptake of calcium into and extrusion of calcium from the mitochondrial matrix is a fundamental biological process that has critical effects on cellular metabolism, signaling, and survival. Disruption of mitochondrial calcium (mCa2+) cycling is implicated in numerous acquired diseases such as heart failure, stroke, neurodegeneration, diabetes, and cancer, and is genetically linked to several inherited neuromuscular disorders. Understanding the mechanisms responsible for mCa2+ exchange therefore holds great promise for the treatment of these diseases. The past decade has seen the genetic identification of many of the key proteins that mediate mitochondrial calcium uptake and efflux. Here, we present an overview of the phenomenon of mCa2+ transport, and a comprehensive examination of the molecular machinery that mediates calcium flux across the inner mitochondrial membrane: the mitochondrial uniporter complex (consisting of MCU, EMRE, MICU1, MICU2, MICU3, MCUB, and MCUR1), NCLX, LETM1, the mitochondrial ryanodine receptor, and the mitochondrial permeability transition pore. We then consider the physiological implications of mCa2+ flux and evaluate how alterations in mCa2+ homeostasis contribute to human disease. This review concludes by highlighting opportunities and challenges for therapeutic intervention in pathologies characterized by aberrant mCa2+ handling and by summarizing critical unanswered questions regarding the biology of mCa2+ flux.
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Affiliation(s)
- Joanne F Garbincius
- Center for Translational Medicine, Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
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13
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Vishnu N, Hamilton A, Bagge A, Wernersson A, Cowan E, Barnard H, Sancak Y, Kamer KJ, Spégel P, Fex M, Tengholm A, Mootha VK, Nicholls DG, Mulder H. Mitochondrial clearance of calcium facilitated by MICU2 controls insulin secretion. Mol Metab 2021; 51:101239. [PMID: 33932586 PMCID: PMC8163986 DOI: 10.1016/j.molmet.2021.101239] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 04/20/2021] [Accepted: 04/21/2021] [Indexed: 01/20/2023] Open
Abstract
OBJECTIVE Transport of Ca2+ into pancreatic β cell mitochondria facilitates nutrient-mediated insulin secretion. However, the underlying mechanism is unclear. Recent establishment of the molecular identity of the mitochondrial Ca2+ uniporter (MCU) and associated proteins allows modification of mitochondrial Ca2+ transport in intact cells. We examined the consequences of deficiency of the accessory protein MICU2 in rat and human insulin-secreting cells and mouse islets. METHODS siRNA silencing of Micu2 in the INS-1 832/13 and EndoC-βH1 cell lines was performed; Micu2-/- mice were also studied. Insulin secretion and mechanistic analyses utilizing live confocal imaging to assess mitochondrial function and intracellular Ca2+ dynamics were performed. RESULTS Silencing of Micu2 abrogated GSIS in the INS-1 832/13 and EndoC-βH1 cells. The Micu2-/- mice also displayed attenuated GSIS. Mitochondrial Ca2+ uptake declined in MICU2-deficient INS-1 832/13 and EndoC-βH1 cells in response to high glucose and high K+. MICU2 silencing in INS-1 832/13 cells, presumably through its effects on mitochondrial Ca2+ uptake, perturbed mitochondrial function illustrated by absent mitochondrial membrane hyperpolarization and lowering of the ATP/ADP ratio in response to elevated glucose. Despite the loss of mitochondrial Ca2+ uptake, cytosolic Ca2+ was lower in siMICU2-treated INS-1 832/13 cells in response to high K+. It was hypothesized that Ca2+ accumulated in the submembrane compartment in MICU2-deficient cells, resulting in desensitization of voltage-dependent Ca2+ channels, lowering total cytosolic Ca2+. Upon high K+ stimulation, MICU2-silenced cells showed higher and prolonged increases in submembrane Ca2+ levels. CONCLUSIONS MICU2 plays a critical role in β cell mitochondrial Ca2+ uptake. β cell mitochondria sequestered Ca2+ from the submembrane compartment, preventing desensitization of voltage-dependent Ca2+ channels and facilitating GSIS.
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Affiliation(s)
- N Vishnu
- Unit of Molecular Metabolism, Lund University Diabetes Center, Lund University, Malmö SE-205 02, Sweden
| | - A Hamilton
- Unit of Molecular Metabolism, Lund University Diabetes Center, Lund University, Malmö SE-205 02, Sweden
| | - A Bagge
- Unit of Molecular Metabolism, Lund University Diabetes Center, Lund University, Malmö SE-205 02, Sweden
| | - A Wernersson
- Unit of Molecular Metabolism, Lund University Diabetes Center, Lund University, Malmö SE-205 02, Sweden
| | - E Cowan
- Unit of Molecular Metabolism, Lund University Diabetes Center, Lund University, Malmö SE-205 02, Sweden
| | - H Barnard
- Unit of Molecular Metabolism, Lund University Diabetes Center, Lund University, Malmö SE-205 02, Sweden
| | - Y Sancak
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - K J Kamer
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - P Spégel
- Unit of Molecular Metabolism, Lund University Diabetes Center, Lund University, Malmö SE-205 02, Sweden
| | - M Fex
- Unit of Molecular Metabolism, Lund University Diabetes Center, Lund University, Malmö SE-205 02, Sweden
| | - A Tengholm
- Department of Medical Cell Biology, Uppsala University, Uppsala SE-751 23, Sweden
| | - V K Mootha
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - D G Nicholls
- Unit of Molecular Metabolism, Lund University Diabetes Center, Lund University, Malmö SE-205 02, Sweden; Buck Institute for Research on Aging, Novato, CA 94945, USA
| | - H Mulder
- Unit of Molecular Metabolism, Lund University Diabetes Center, Lund University, Malmö SE-205 02, Sweden.
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14
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Madec AM, Perrier J, Panthu B, Dingreville F. Role of mitochondria-associated endoplasmic reticulum membrane (MAMs) interactions and calcium exchange in the development of type 2 diabetes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 363:169-202. [PMID: 34392929 DOI: 10.1016/bs.ircmb.2021.06.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Glucotoxicity-induced β-cell dysfunction in type 2 diabetes is associated with alterations of mitochondria and the endoplasmic reticulum (ER). Mitochondria and ER form a network in cells that controls cell function and fate. Mitochondria of the pancreatic β cell play a central role in the secretion of insulin in response to glucose through their ability to produce ATP. Both organelles interact at contact sites, defined as mitochondria-associated membranes (MAMs), which were recently implicated in the regulation of glucose homeostasis. Here, we review MAM functions in the cell and we focus on the crosstalk between the ER and Mitochondria in the context of T2D, highlighting the pivotal role played by MAMs especially in β cells through inter-organelle calcium exchange and glucotoxicity-associated β cell dysfunction.
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Affiliation(s)
| | - Johan Perrier
- CarMeN Laboratory, INSERM U1060, INRA U1397, Lyon, France
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15
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Casella A, Panitch A, Leach JK. Endogenous Electric Signaling as a Blueprint for Conductive Materials in Tissue Engineering. Bioelectricity 2021; 3:27-41. [PMID: 34476376 PMCID: PMC8370482 DOI: 10.1089/bioe.2020.0027] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Bioelectricity plays an important role in cell behavior and tissue modulation, but is understudied in tissue engineering research. Endogenous electrical signaling arises from the transmembrane potential inherent to all cells and contributes to many cell behaviors, including migration, adhesion, proliferation, and differentiation. Electrical signals are also involved in tissue development and repair. Synthetic and natural conductive materials are under investigation for leveraging endogenous electrical signaling cues in tissue engineering applications due to their ability to direct cell differentiation, aid in maturing electroactive cell types, and promote tissue functionality. In this review, we provide a brief overview of bioelectricity and its impact on cell behavior, report recent literature using conductive materials for tissue engineering, and discuss opportunities within the field to improve experimental design when using conductive substrates.
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Affiliation(s)
- Alena Casella
- Department of Biomedical Engineering, University of California, Davis, Davis, California, USA
| | - Alyssa Panitch
- Department of Biomedical Engineering, University of California, Davis, Davis, California, USA
- Department of Surgery and UC Davis Health, Sacramento, California, USA
| | - J. Kent Leach
- Department of Biomedical Engineering, University of California, Davis, Davis, California, USA
- Department of Orthopaedic Surgery, UC Davis Health, Sacramento, California, USA
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16
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Karamian M, Moossavi M, Hemmati M. From diabetes to renal aging: the therapeutic potential of adiponectin. J Physiol Biochem 2021; 77:205-214. [PMID: 33555532 DOI: 10.1007/s13105-021-00790-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 01/14/2021] [Indexed: 12/11/2022]
Abstract
Nowadays, the complications related to diabetes, such as nephropathy, cardiovascular problems, and aging, are highly being considered. Renal cell aging is affected by various mechanisms of inflammation, oxidative stress, and basement membrane thickening, which are significant causes of renal dysfunction in diabetes. Due to recent studies, adiponectin plays a key role in diabetes-related kidney diseases as a fat-derived hormone. In diabetes, reduced adiponectin levels are associated to renal cell aging. Oxidative stress and related signaling pathways are the main routes in which adiponectin may be effective to decline diabetes-associated aging. Therefore, adiponectin signaling in target tissues becomes one of the research areas of interest in metabolism and clinical medicine. Studies on adiponectin signaling will increase our understanding of adiponectin role in diabetes-linked diseases as well as shortening life span conditions which may guide the design of antidiabetic and anti-aging drugs.
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Affiliation(s)
- Mehdi Karamian
- Department of Parasitology and Mycology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Maryam Moossavi
- Student Research Committee, Birjand University of Medical Sciences, Birjand, Iran
| | - Mina Hemmati
- Department of Biochemistry, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran.
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17
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Ježek P, Holendová B, Jabůrek M, Tauber J, Dlasková A, Plecitá-Hlavatá L. The Pancreatic β-Cell: The Perfect Redox System. Antioxidants (Basel) 2021; 10:antiox10020197. [PMID: 33572903 PMCID: PMC7912581 DOI: 10.3390/antiox10020197] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/20/2021] [Accepted: 01/25/2021] [Indexed: 12/12/2022] Open
Abstract
Pancreatic β-cell insulin secretion, which responds to various secretagogues and hormonal regulations, is reviewed here, emphasizing the fundamental redox signaling by NADPH oxidase 4- (NOX4-) mediated H2O2 production for glucose-stimulated insulin secretion (GSIS). There is a logical summation that integrates both metabolic plus redox homeostasis because the ATP-sensitive K+ channel (KATP) can only be closed when both ATP and H2O2 are elevated. Otherwise ATP would block KATP, while H2O2 would activate any of the redox-sensitive nonspecific calcium channels (NSCCs), such as TRPM2. Notably, a 100%-closed KATP ensemble is insufficient to reach the -50 mV threshold plasma membrane depolarization required for the activation of voltage-dependent Ca2+ channels. Open synergic NSCCs or Cl- channels have to act simultaneously to reach this threshold. The resulting intermittent cytosolic Ca2+-increases lead to the pulsatile exocytosis of insulin granule vesicles (IGVs). The incretin (e.g., GLP-1) amplification of GSIS stems from receptor signaling leading to activating the phosphorylation of TRPM channels and effects on other channels to intensify integral Ca2+-influx (fortified by endoplasmic reticulum Ca2+). ATP plus H2O2 are also required for branched-chain ketoacids (BCKAs); and partly for fatty acids (FAs) to secrete insulin, while BCKA or FA β-oxidation provide redox signaling from mitochondria, which proceeds by H2O2 diffusion or hypothetical SH relay via peroxiredoxin "redox kiss" to target proteins.
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18
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Seok J, Jun S, Lee JO, Kim GJ. Mitochondrial Dynamics in Placenta-Derived Mesenchymal Stem Cells Regulate the Invasion Activity of Trophoblast. Int J Mol Sci 2020; 21:ijms21228599. [PMID: 33202697 PMCID: PMC7696686 DOI: 10.3390/ijms21228599] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 11/02/2020] [Accepted: 11/12/2020] [Indexed: 12/21/2022] Open
Abstract
Mitochondrial dynamics are involved in many cellular events, including the proliferation, differentiation, and invasion/migration of normal as well as cancerous cells. Human placenta-derived mesenchymal stem cells (PD-MSCs) were known to regulate the invasion activity of trophoblasts. However, the effects of PD-MSCs on mitochondrial function in trophoblasts are still insufficiently understood. Therefore, the objectives of this study are to analyze the factors related to mitochondrial function and investigate the correlation between trophoblast invasion and mitophagy via PD-MSC cocultivation. We assess invasion ability and mitochondrial function in invasive trophoblasts according to PD-MSC cocultivation by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and extracellular flux (XF) assay. Under PD-MSCs co-cultivation, invasion activity of a trophoblast is increased via activation of the Rho signaling pathway as well as Matrix metalloproteinases (MMPs). Additionally, the expression of mitochondrial function (e.g., reactive oxygen species (ROS), calcium, and adenosine triphosphate (ATP) synthesis) in trophoblasts are increased via PD-MSCs co-cultivation. Finally, PD-MSCs regulate mitochondrial autophagy factors in invasive trophoblasts via regulating the balance between PTEN-induced putative kinase 1 (PINK1) and parkin RBR E3 ubiquitin protein ligase (PARKIN) expression. Taken together, these results demonstrate that PD-MSCs enhance the invasion ability of trophoblasts via altering mitochondrial dynamics. These results support the fundamental mechanism of trophoblast invasion via mitochondrial function and provide a new stem cell therapy for infertility.
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Affiliation(s)
- Jin Seok
- Department of Biomedical Science, CHA University, Seongnam 13488, Korea; (J.S.); (S.J.)
| | - Sujin Jun
- Department of Biomedical Science, CHA University, Seongnam 13488, Korea; (J.S.); (S.J.)
| | - Jung Ok Lee
- Department of Anatomy, Korea University College of Medicine, Seoul 02841, Korea;
| | - Gi Jin Kim
- Department of Biomedical Science, CHA University, Seongnam 13488, Korea; (J.S.); (S.J.)
- Correspondence: ; Tel.: +82-31-881-7245
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19
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Mitochondrial Carriers Regulating Insulin Secretion Profiled in Human Islets upon Metabolic Stress. Biomolecules 2020; 10:biom10111543. [PMID: 33198243 PMCID: PMC7697104 DOI: 10.3390/biom10111543] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/28/2020] [Accepted: 11/10/2020] [Indexed: 12/27/2022] Open
Abstract
Chronic exposure of β-cells to nutrient-rich metabolic stress impairs mitochondrial metabolism and its coupling to insulin secretion. We exposed isolated human islets to different metabolic stresses for 3 days: 0.4 mM oleate or 0.4 mM palmitate at physiological 5.5 mM glucose (lipotoxicity), high 25 mM glucose (glucotoxicity), and high 25 mM glucose combined with 0.4 mM oleate and/or palmitate (glucolipotoxicity). Then, we profiled the mitochondrial carriers and associated genes with RNA-Seq. Diabetogenic conditions, and in particular glucotoxicity, increased expression of several mitochondrial solute carriers in human islets, such as the malate carrier DIC, the α-ketoglutarate-malate exchanger OGC, and the glutamate carrier GC1. Glucotoxicity also induced a general upregulation of the electron transport chain machinery, while palmitate largely counteracted this effect. Expression of different components of the TOM/TIM mitochondrial protein import system was increased by glucotoxicity, whereas glucolipotoxicity strongly upregulated its receptor subunit TOM70. Expression of the mitochondrial calcium uniporter MCU was essentially preserved by metabolic stresses. However, glucotoxicity altered expression of regulatory elements of calcium influx as well as the Na+/Ca2+ exchanger NCLX, which mediates calcium efflux. Overall, the expression profile of mitochondrial carriers and associated genes was modified by the different metabolic stresses exhibiting nutrient-specific signatures.
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20
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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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21
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Georgiadou E, Haythorne E, Dickerson MT, Lopez-Noriega L, Pullen TJ, da Silva Xavier G, Davis SPX, Martinez-Sanchez A, Semplici F, Rizzuto R, McGinty JA, French PM, Cane MC, Jacobson DA, Leclerc I, Rutter GA. The pore-forming subunit MCU of the mitochondrial Ca 2+ uniporter is required for normal glucose-stimulated insulin secretion in vitro and in vivo in mice. Diabetologia 2020; 63:1368-1381. [PMID: 32350566 PMCID: PMC7286857 DOI: 10.1007/s00125-020-05148-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 02/27/2020] [Indexed: 12/28/2022]
Abstract
AIMS/HYPOTHESIS Mitochondrial oxidative metabolism is central to glucose-stimulated insulin secretion (GSIS). Whether Ca2+ uptake into pancreatic beta cell mitochondria potentiates or antagonises this process is still a matter of debate. Although the mitochondrial Ca2+ importer (MCU) complex is thought to represent the main route for Ca2+ transport across the inner mitochondrial membrane, its role in beta cells has not previously been examined in vivo. METHODS Here, we inactivated the pore-forming subunit of the MCU, encoded by Mcu, selectively in mouse beta cells using Ins1Cre-mediated recombination. Whole or dissociated pancreatic islets were isolated and used for live beta cell fluorescence imaging of cytosolic or mitochondrial Ca2+ concentration and ATP production in response to increasing glucose concentrations. Electrophysiological recordings were also performed on whole islets. Serum and blood samples were collected to examine oral and i.p. glucose tolerance. RESULTS Glucose-stimulated mitochondrial Ca2+ accumulation (p< 0.05), ATP production (p< 0.05) and insulin secretion (p< 0.01) were strongly inhibited in beta cell-specific Mcu-null (βMcu-KO) animals, in vitro, as compared with wild-type (WT) mice. Interestingly, cytosolic Ca2+ concentrations increased (p< 0.001), whereas mitochondrial membrane depolarisation improved in βMcu-KO animals. βMcu-KO mice displayed impaired in vivo insulin secretion at 5 min (p< 0.001) but not 15 min post-i.p. injection of glucose, whilst the opposite phenomenon was observed following an oral gavage at 5 min. Unexpectedly, glucose tolerance was improved (p< 0.05) in young βMcu-KO (<12 weeks), but not in older animals vs WT mice. CONCLUSIONS/INTERPRETATION MCU is crucial for mitochondrial Ca2+ uptake in pancreatic beta cells and is required for normal GSIS. The apparent compensatory mechanisms that maintain glucose tolerance in βMcu-KO mice remain to be established.
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Affiliation(s)
- Eleni Georgiadou
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Elizabeth Haythorne
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Livia Lopez-Noriega
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Timothy J Pullen
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Gabriela da Silva Xavier
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Samuel P X Davis
- Photonics Group, Department of Physics, Imperial College London, London, UK
| | - Aida Martinez-Sanchez
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Francesca Semplici
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - James A McGinty
- Photonics Group, Department of Physics, Imperial College London, London, UK
| | - Paul M French
- Photonics Group, Department of Physics, Imperial College London, London, UK
| | - Matthew C Cane
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Isabelle Leclerc
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, 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, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, Du Cane Road, London, W12 0NN, UK.
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22
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Verma G, Dixit A, Nunemaker CS. A Putative Prohibitin-Calcium Nexus in β-Cell Mitochondria and Diabetes. J Diabetes Res 2020; 2020:7814628. [PMID: 33354575 PMCID: PMC7737164 DOI: 10.1155/2020/7814628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 08/01/2020] [Accepted: 08/05/2020] [Indexed: 12/21/2022] Open
Abstract
The role of mitochondria in apoptosis is well known; however, the mechanisms linking mitochondria to the proapoptotic effects of proinflammatory cytokines, hyperglycemia, and glucolipotoxicity are not completely understood. Complex Ca2+ signaling has emerged as a critical contributor to these proapoptotic effects and has gained significant attention in regulating the signaling processes of mitochondria. In pancreatic β-cells, Ca2+ plays an active role in β-cell function and survival. Prohibitin (PHB), a mitochondrial chaperone, is actively involved in maintaining the architecture of mitochondria. However, its possible interaction with Ca2+-activated signaling pathways has not been explored. The present review aims to examine potential crosstalk between Ca2+ signaling and PHB function in pancreatic β-cells. Moreover, this review will focus on the effects of cytokines and glucolipotoxicity on Ca2+ signaling and its possible interaction with PHB. Improved understanding of this important mitochondrial protein may aid in the design of more targeted drugs to identify specific pathways involved with stress-induced dysfunction in the β-cell.
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Affiliation(s)
- Gaurav Verma
- Molecular Metabolism, Lund University Diabetes Centre, Malmö -21428, Sweden
- School of Biotechnology, Jawaharlal Nehru University, -110067, New Delhi, India
| | - Aparna Dixit
- School of Biotechnology, Jawaharlal Nehru University, -110067, New Delhi, India
| | - Craig S. Nunemaker
- HCOM-Biomedical Sciences, Ohio University, Athens Camp, US-45701 Ohio, USA
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23
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Dingreville F, Panthu B, Thivolet C, Ducreux S, Gouriou Y, Pesenti S, Chauvin MA, Chikh K, Errazuriz-Cerda E, Van Coppenolle F, Rieusset J, Madec AM. Differential Effect of Glucose on ER-Mitochondria Ca 2+ Exchange Participates in Insulin Secretion and Glucotoxicity-Mediated Dysfunction of β-Cells. Diabetes 2019; 68:1778-1794. [PMID: 31175102 DOI: 10.2337/db18-1112] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 06/04/2019] [Indexed: 11/13/2022]
Abstract
Glucotoxicity-induced β-cell dysfunction in type 2 diabetes is associated with alterations of mitochondria and the endoplasmic reticulum (ER). Both organelles interact at contact sites, defined as mitochondria-associated membranes (MAMs), which were recently implicated in the regulation of glucose homeostasis. The role of MAMs in β-cells is still largely unknown, and their implication in glucotoxicity-associated β-cell dysfunction remains to be defined. Here, we report that acute glucose treatment stimulated ER-mitochondria interactions and calcium (Ca2+) exchange in INS-1E cells, whereas disruption of MAMs altered glucose-stimulated insulin secretion (GSIS). Conversely, chronic incubations with high glucose of either INS-1E cells or human pancreatic islets altered GSIS and concomitantly reduced ER Ca2+ store, increased basal mitochondrial Ca2+, and reduced ATP-stimulated ER-mitochondria Ca2+ exchanges, despite an increase of organelle interactions. Furthermore, glucotoxicity-induced perturbations of Ca2+ signaling are associated with ER stress, altered mitochondrial respiration, and mitochondria fragmentation, and these organelle stresses may participate in increased organelle tethering as a protective mechanism. Last, sustained induction of ER-mitochondria interactions using a linker reduced organelle Ca2+ exchange, induced mitochondrial fission, and altered GSIS. Therefore, dynamic organelle coupling participates in GSIS in β-cells, and over time, disruption of organelle Ca2+ exchange might be a novel mechanism contributing to glucotoxicity-induced β-cell dysfunction.
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Affiliation(s)
- Florian Dingreville
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Baptiste Panthu
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Charles Thivolet
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
- Department of Endocrinology and Diabetes, Hospices Civils de Lyon, Hopital Lyon Sud, Pierre-Bénite, France
| | - Sylvie Ducreux
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Yves Gouriou
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Sandra Pesenti
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Marie-Agnès Chauvin
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Karim Chikh
- Department of Endocrinology and Diabetes, Hospices Civils de Lyon, Hopital Lyon Sud, Pierre-Bénite, France
| | | | - Fabien Van Coppenolle
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Jennifer Rieusset
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Anne-Marie Madec
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
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24
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Chavez-Abiega S, Goedhart J, Bruggeman FJ. Physical biology of GPCR signalling dynamics inferred from fluorescence spectroscopy and imaging. Curr Opin Struct Biol 2019; 55:204-211. [PMID: 31319372 DOI: 10.1016/j.sbi.2019.05.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/30/2019] [Accepted: 05/08/2019] [Indexed: 12/20/2022]
Abstract
The physical biology of G protein-coupled receptor (GPCR) signalling can be inferred from imaging of single molecules and single living cells. In this opinion paper, we highlight recent developments in technologies to study GPCR signalling in vitro and in cyto. We start from mobility and localisation characteristics of single receptors in membranes. Subsequently, we discuss the kinetics of shifts in receptor-conformation equilibrium due to allosteric binding events and G protein activation. We continue with recent insights into downstream signalling and the role of delayed negative feedback to suppress GPCR signalling. Finally, we discuss new strategies to reveal how the multiplex signalling responses of cells to ligand mixtures, mediated by their entire receptor arsenal, can be disentangled, using single-cell data.
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Affiliation(s)
- Sergei Chavez-Abiega
- Section Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, NL-1098 XH, Amsterdam, The Netherlands; Section Systems Bioinformatics, Amsterdam Institute for Molecules, Medicines and Systems, VU University, De Boelelaan 1085, NL-1081 HV, Amsterdam, The Netherlands
| | - Joachim Goedhart
- Section Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, NL-1098 XH, Amsterdam, The Netherlands
| | - Frank Johannes Bruggeman
- Section Systems Bioinformatics, Amsterdam Institute for Molecules, Medicines and Systems, VU University, De Boelelaan 1085, NL-1081 HV, Amsterdam, The Netherlands.
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25
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Sabatini PV, Speckmann T, Lynn FC. Friend and foe: β-cell Ca 2+ signaling and the development of diabetes. Mol Metab 2019; 21:1-12. [PMID: 30630689 PMCID: PMC6407368 DOI: 10.1016/j.molmet.2018.12.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 12/03/2018] [Accepted: 12/19/2018] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND The divalent cation Calcium (Ca2+) regulates a wide range of processes in disparate cell types. Within insulin-producing β-cells, increases in cytosolic Ca2+ directly stimulate insulin vesicle exocytosis, but also initiate multiple signaling pathways. Mediated through activation of downstream kinases and transcription factors, Ca2+-regulated signaling pathways leverage substantial influence on a number of critical cellular processes within the β-cell. Additionally, there is evidence that prolonged activation of these same pathways is detrimental to β-cell health and may contribute to Type 2 Diabetes pathogenesis. SCOPE OF REVIEW This review aims to briefly highlight canonical Ca2+ signaling pathways in β-cells and how β-cells regulate the movement of Ca2+ across numerous organelles and microdomains. As a main focus, this review synthesizes experimental data from in vitro and in vivo models on both the beneficial and detrimental effects of Ca2+ signaling pathways for β-cell function and health. MAJOR CONCLUSIONS Acute increases in intracellular Ca2+ stimulate a number of signaling cascades, resulting in (de-)phosphorylation events and activation of downstream transcription factors. The short-term stimulation of these Ca2+ signaling pathways promotes numerous cellular processes critical to β-cell function, including increased viability, replication, and insulin production and secretion. Conversely, chronic stimulation of Ca2+ signaling pathways increases β-cell ER stress and results in the loss of β-cell differentiation status. Together, decades of study demonstrate that Ca2+ movement is tightly regulated within the β-cell, which is at least partially due to its dual roles as a potent signaling molecule.
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Affiliation(s)
- Paul V Sabatini
- Diabetes Research Group, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada; Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada; Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Thilo Speckmann
- Diabetes Research Group, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada; Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Francis C Lynn
- Diabetes Research Group, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada; Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
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Frank JA, Broichhagen J, Yushchenko DA, Trauner D, Schultz C, Hodson DJ. Optical tools for understanding the complexity of β-cell signalling and insulin release. Nat Rev Endocrinol 2018; 14:721-737. [PMID: 30356209 DOI: 10.1038/s41574-018-0105-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Following stimulation, pancreatic β-cells must orchestrate a plethora of signalling events to ensure the appropriate release of insulin and maintenance of normal glucose homeostasis. Failure at any point in this cascade leads to impaired insulin secretion, elevated blood levels of glucose and eventually type 2 diabetes mellitus. Likewise, β-cell replacement or regeneration strategies for the treatment of both type 1 and type 2 diabetes mellitus might fail if the correct cell signalling phenotype cannot be faithfully recreated. However, current understanding of β-cell function is complicated because of the highly dynamic nature of their intracellular and intercellular signalling as well as insulin release itself. β-Cells must precisely integrate multiple signals stemming from multiple cues, often with differing intensities, frequencies and cellular and subcellular localizations, before converging these signals onto insulin exocytosis. In this respect, optical approaches with high resolution in space and time are extremely useful for properly deciphering the complexity of β-cell signalling. An increased understanding of β-cell signalling might identify new mechanisms underlying insulin release, with relevance for future drug therapy and de novo stem cell engineering of functional islets.
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Affiliation(s)
- James A Frank
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Johannes Broichhagen
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Dmytro A Yushchenko
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Dirk Trauner
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Chemistry, New York University, New York, NY, USA
| | - Carsten Schultz
- European Molecular Biology Laboratory (EMBL), Cell Biology and Biophysics Unit, Heidelberg, Germany.
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR, USA.
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR) and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK.
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK.
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27
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Saeedi Borujeni MJ, Esfandiary E, Baradaran A, Valiani A, Ghanadian M, Codoñer-Franch P, Basirat R, Alonso-Iglesias E, Mirzaei H, Yazdani A. Molecular aspects of pancreatic β-cell dysfunction: Oxidative stress, microRNA, and long noncoding RNA. J Cell Physiol 2018; 234:8411-8425. [PMID: 30565679 DOI: 10.1002/jcp.27755] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 10/23/2018] [Indexed: 02/06/2023]
Abstract
Metabolic syndrome is known as a frequent precursor of type 2 diabetes mellitus (T2D). This disease could affect 8% of the people worldwide. Given that pancreatic β-cell dysfunction and loss have central roles in the initiation and progression of the disease, the understanding of cellular and molecular pathways associated with pancreatic β-cell dysfunction can provide more information about the underlying pathways involved in T2D. Multiple lines evidence indicated that oxidative stress, microRNA, and long noncoding RNA play significant roles in various steps of diseases. Oxidative stress is one of the important factors involved in T2D pathogenesis. This could affect the function and survival of the β cell via activation or inhibition of several processes and targets, such as receptor-signal transduction, enzyme activity, gene expression, ion channel transport, and apoptosis. Besides oxidative stress, microRNAs and noncoding RNAs have emerged as epigenetic regulators that could affect pancreatic β-cell dysfunction. These molecules exert their effects via targeting a variety of cellular and molecular pathways involved in T2D pathogenesis. Here, we summarized the molecular aspects of pancreatic β-cell dysfunction. Moreover, we highlighted the roles of oxidative stress, microRNAs, and noncoding RNAs in pancreatic β-cell dysfunction.
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Affiliation(s)
- Mohammad Javad Saeedi Borujeni
- Department of Anatomical Sciences and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Ebrahim Esfandiary
- Department of Anatomical Sciences and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Azar Baradaran
- Department of Pathology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Ali Valiani
- Department of Anatomical Sciences and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mustafa Ghanadian
- Department of Pharmacognosy, Faculty of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Pilar Codoñer-Franch
- Department of Pediatrics, Obstetrics and Gynecology, University of Valencia, Valencia, Spain
| | - Reyhane Basirat
- Department of Clinical Nutrition, School of Nutrition and Food Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
| | | | - Hamed Mirzaei
- Research Center for Biochemistry and Nutrition in Metabolic Diseases, Kashan University of Medical Sciences, Kashan, Iran
| | - Amid Yazdani
- School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
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28
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Giorgi C, Marchi S, Pinton P. The machineries, regulation and cellular functions of mitochondrial calcium. Nat Rev Mol Cell Biol 2018; 19:713-730. [PMID: 30143745 DOI: 10.1038/s41580-018-0052-8] [Citation(s) in RCA: 479] [Impact Index Per Article: 79.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Calcium ions (Ca2+) are some of the most versatile signalling molecules, and they have many physiological functions, prominently including muscle contraction, neuronal excitability, cell migration and cell growth. By sequestering and releasing Ca2+, mitochondria serve as important regulators of cellular Ca2+. Mitochondrial Ca2+ also has other important functions, such as regulation of mitochondrial metabolism, ATP production and cell death. In recent years, identification of the molecular machinery regulating mitochondrial Ca2+ accumulation and efflux has expanded the number of (patho)physiological conditions that rely on mitochondrial Ca2+ homeostasis. Thus, expanding the understanding of the mechanisms of mitochondrial Ca2+ regulation and function in different cell types is an important task in biomedical research, which offers the possibility of targeting mitochondrial Ca2+ machinery for the treatment of several disorders.
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Affiliation(s)
- Carlotta Giorgi
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Saverio Marchi
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Paolo Pinton
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy. .,Maria Cecilia Hospital, GVM Care and Research, Cotignola, Ravenna, Italy.
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29
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Filadi R, Basso E, Lefkimmiatis K, Pozzan T. Beyond Intracellular Signaling: The Ins and Outs of Second Messengers Microdomains. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 981:279-322. [PMID: 29594866 DOI: 10.1007/978-3-319-55858-5_12] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A typical characteristic of eukaryotic cells compared to prokaryotes is represented by the spatial heterogeneity of the different structural and functional components: for example, most of the genetic material is surrounded by a highly specific membrane structure (the nuclear membrane), continuous with, yet largely different from, the endoplasmic reticulum (ER); oxidative phosphorylation is carried out by organelles enclosed by a double membrane, the mitochondria; in addition, distinct domains, enriched in specific proteins, are present in the plasma membrane (PM) of most cells. Less obvious, but now generally accepted, is the notion that even the concentration of small molecules such as second messengers (Ca2+ and cAMP in particular) can be highly heterogeneous within cells. In the case of most organelles, the differences in the luminal levels of second messengers depend either on the existence on their membrane of proteins that allow the accumulation/release of the second messenger (e.g., in the case of Ca2+, pumps, exchangers or channels), or on the synthesis and degradation of the specific molecule within the lumen (the autonomous intramitochondrial cAMP system). It needs stressing that the existence of a surrounding membrane does not necessarily imply the existence of a gradient between the cytosol and the organelle lumen. For example, the nuclear membrane is highly permeable to both Ca2+ and cAMP (nuclear pores are permeable to solutes up to 50 kDa) and differences in [Ca2+] or [cAMP] between cytoplasm and nucleoplasm are not seen in steady state and only very transiently during cell activation. A similar situation has been observed, as far as Ca2+ is concerned, in peroxisomes.
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Affiliation(s)
- Riccardo Filadi
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Emy Basso
- Institute of Neuroscience, Padova Section, National Research Council, Padova, Italy
| | - Konstantinos Lefkimmiatis
- Institute of Neuroscience, Padova Section, National Research Council, Padova, Italy
- Venetian Institute of Molecular Medicine, Padova, Italy
| | - Tullio Pozzan
- Department of Biomedical Sciences, University of Padova, Padova, Italy.
- Institute of Neuroscience, Padova Section, National Research Council, Padova, Italy.
- Venetian Institute of Molecular Medicine, Padova, Italy.
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30
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Mitochondrial junctions with cellular organelles: Ca 2+ signalling perspective. Pflugers Arch 2018; 470:1181-1192. [PMID: 29982949 PMCID: PMC6060751 DOI: 10.1007/s00424-018-2179-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 06/27/2018] [Accepted: 06/29/2018] [Indexed: 01/21/2023]
Abstract
Cellular organelles form multiple junctional complexes with one another and the emerging research area dealing with such structures and their functions is undergoing explosive growth. A new research journal named “Contact” has been recently established to facilitate the development of this research field. The current consensus is to define an organellar junction by the maximal distance between the participating organelles; and the gap of 30 nm or less is considered appropriate for classifying such structures as junctions or membrane contact sites. Ideally, the organellar junction should have a functional significance, i.e. facilitate transfer of calcium, sterols, phospholipids, iron and possibly other substances between the organelles (Carrasco and Meyer in Annu Rev Biochem 80:973–1000, 2011; Csordas et al. in Trends Cell Biol 28:523–540, 2018; Phillips and Voeltz in Nat Rev Mol Cell Biol 17:69–82, 2016; Prinz in J Cell Biol 205:759–769, 2014). It is also important to note that the junction is not just a result of a random organelle collision but have active and specific formation, stabilisation and disassembly mechanisms. The nature of these mechanisms and their role in physiology/pathophysiology are the main focus of an emerging research field. In this review, we will briefly describe junctional complexes formed by cellular organelles and then focus on the junctional complexes that are formed by mitochondria with other organelles and the role of these complexes in regulating Ca2+ signalling.
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31
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Tokarz VL, MacDonald PE, Klip A. The cell biology of systemic insulin function. J Cell Biol 2018; 217:2273-2289. [PMID: 29622564 PMCID: PMC6028526 DOI: 10.1083/jcb.201802095] [Citation(s) in RCA: 230] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 03/21/2018] [Accepted: 03/23/2018] [Indexed: 12/12/2022] Open
Abstract
Insulin is the paramount anabolic hormone, promoting carbon energy deposition in the body. Its synthesis, quality control, delivery, and action are exquisitely regulated by highly orchestrated intracellular mechanisms in different organs or "stations" of its bodily journey. In this Beyond the Cell review, we focus on these five stages of the journey of insulin through the body and the captivating cell biology that underlies the interaction of insulin with each organ. We first analyze insulin's biosynthesis in and export from the β-cells of the pancreas. Next, we focus on its first pass and partial clearance in the liver with its temporality and periodicity linked to secretion. Continuing the journey, we briefly describe insulin's action on the blood vasculature and its still-debated mechanisms of exit from the capillary beds. Once in the parenchymal interstitium of muscle and adipose tissue, insulin promotes glucose uptake into myofibers and adipocytes, and we elaborate on the intricate signaling and vesicle traffic mechanisms that underlie this fundamental function. Finally, we touch upon the renal degradation of insulin to end its action. Cellular discernment of insulin's availability and action should prove critical to understanding its pivotal physiological functions and how their failure leads to diabetes.
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Affiliation(s)
- Victoria L Tokarz
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Patrick E MacDonald
- Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada
| | - Amira Klip
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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32
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Adam J, Ramracheya R, Chibalina MV, Ternette N, Hamilton A, Tarasov AI, Zhang Q, Rebelato E, Rorsman NJG, Martín-Del-Río R, Lewis A, Özkan G, Do HW, Spégel P, Saitoh K, Kato K, Igarashi K, Kessler BM, Pugh CW, Tamarit-Rodriguez J, Mulder H, Clark A, Frizzell N, Soga T, Ashcroft FM, Silver A, Pollard PJ, Rorsman P. Fumarate Hydratase Deletion in Pancreatic β Cells Leads to Progressive Diabetes. Cell Rep 2018; 20:3135-3148. [PMID: 28954230 PMCID: PMC5637167 DOI: 10.1016/j.celrep.2017.08.093] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 07/27/2017] [Accepted: 08/29/2017] [Indexed: 12/31/2022] Open
Abstract
We explored the role of the Krebs cycle enzyme fumarate hydratase (FH) in glucose-stimulated insulin secretion (GSIS). Mice lacking Fh1 in pancreatic β cells (Fh1βKO mice) appear normal for 6–8 weeks but then develop progressive glucose intolerance and diabetes. Glucose tolerance is rescued by expression of mitochondrial or cytosolic FH but not by deletion of Hif1α or Nrf2. Progressive hyperglycemia in Fh1βKO mice led to dysregulated metabolism in β cells, a decrease in glucose-induced ATP production, electrical activity, cytoplasmic [Ca2+]i elevation, and GSIS. Fh1 loss resulted in elevated intracellular fumarate, promoting succination of critical cysteines in GAPDH, GMPR, and PARK 7/DJ-1 and cytoplasmic acidification. Intracellular fumarate levels were increased in islets exposed to high glucose and in islets from human donors with type 2 diabetes (T2D). The impaired GSIS in islets from diabetic Fh1βKO mice was ameliorated after culture under normoglycemic conditions. These studies highlight the role of FH and dysregulated mitochondrial metabolism in T2D. Fh1 loss in β cells causes progressive Hif1α-independent diabetes Fh1 loss in β cells impairs ATP generation, electrical activity, and GSIS Elevated fumarate is a feature of diabetic murine and human islets “Normoglycemia” restores GSIS in Fh1βKO islets
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Affiliation(s)
- Julie Adam
- Radcliffe Department of Medicine, OCDEM, Churchill Hospital, University of Oxford, Oxford OX3 7LE, UK; Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK; Nuffield Department of Medicine, NDMRB, University of Oxford, Oxford OX3 7FZ, UK.
| | - Reshma Ramracheya
- Radcliffe Department of Medicine, OCDEM, Churchill Hospital, University of Oxford, Oxford OX3 7LE, UK
| | - Margarita V Chibalina
- Radcliffe Department of Medicine, OCDEM, Churchill Hospital, University of Oxford, Oxford OX3 7LE, UK
| | - Nicola Ternette
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7FZ, UK
| | - Alexander Hamilton
- Radcliffe Department of Medicine, OCDEM, Churchill Hospital, University of Oxford, Oxford OX3 7LE, UK
| | - Andrei I Tarasov
- Radcliffe Department of Medicine, OCDEM, Churchill Hospital, University of Oxford, Oxford OX3 7LE, UK
| | - Quan Zhang
- Radcliffe Department of Medicine, OCDEM, Churchill Hospital, University of Oxford, Oxford OX3 7LE, UK
| | - Eduardo Rebelato
- Radcliffe Department of Medicine, OCDEM, Churchill Hospital, University of Oxford, Oxford OX3 7LE, UK; Department of Biophysics, Federal University of Sao Paulo, Sao Paulo 04023-062, Brazil
| | - Nils J G Rorsman
- Radcliffe Department of Medicine, OCDEM, Churchill Hospital, University of Oxford, Oxford OX3 7LE, UK
| | - Rafael Martín-Del-Río
- Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Ramón y Cajal Hospital, Madrid, Spain
| | - Amy Lewis
- Centre for Genomics and Child Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - Gizem Özkan
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK
| | - Hyun Woong Do
- Radcliffe Department of Medicine, OCDEM, Churchill Hospital, University of Oxford, Oxford OX3 7LE, UK
| | - Peter Spégel
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, 221 00 Lund, Sweden
| | - Kaori Saitoh
- Institute for Advanced Biosciences, Keio University, 246-2 Mizukami, Tsuruoka, Yamagata 997-0052, Japan
| | - Keiko Kato
- Institute for Advanced Biosciences, Keio University, 246-2 Mizukami, Tsuruoka, Yamagata 997-0052, Japan
| | - Kaori Igarashi
- Institute for Advanced Biosciences, Keio University, 246-2 Mizukami, Tsuruoka, Yamagata 997-0052, Japan
| | - Benedikt M Kessler
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7FZ, UK
| | - Christopher W Pugh
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK; Nuffield Department of Medicine, NDMRB, University of Oxford, Oxford OX3 7FZ, UK
| | - Jorge Tamarit-Rodriguez
- Biochemistry Department, School of Medicine, Complutense University of Madrid, 28040 Madrid, Spain
| | - Hindrik Mulder
- Lund University Diabetes Centre, Unit of Molecular Metabolism, Clinical Research Centre, Malmo University Hospital, 20502 Malmo, Sweden
| | - Anne Clark
- Radcliffe Department of Medicine, OCDEM, Churchill Hospital, University of Oxford, Oxford OX3 7LE, UK
| | - Norma Frizzell
- Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC 29208, USA
| | - Tomoyoshi Soga
- Institute for Advanced Biosciences, Keio University, 246-2 Mizukami, Tsuruoka, Yamagata 997-0052, Japan
| | - Frances M Ashcroft
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, UK
| | - Andrew Silver
- Centre for Genomics and Child Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - Patrick J Pollard
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN, UK; Department of Physiology, Institute of Neuroscience and Physiology, University of Göteborg, 405 30 Göteborg, Sweden
| | - Patrik Rorsman
- Radcliffe Department of Medicine, OCDEM, Churchill Hospital, University of Oxford, Oxford OX3 7LE, UK; Department of Physiology, Institute of Neuroscience and Physiology, University of Göteborg, 405 30 Göteborg, Sweden.
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Paupe V, Prudent J. New insights into the role of mitochondrial calcium homeostasis in cell migration. Biochem Biophys Res Commun 2018; 500:75-86. [PMID: 28495532 PMCID: PMC5930976 DOI: 10.1016/j.bbrc.2017.05.039] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 05/07/2017] [Indexed: 01/23/2023]
Abstract
Mitochondria are dynamic organelles involved in numerous physiological functions. Beyond their function in ATP production, mitochondria regulate cell death, reactive oxygen species (ROS) generation, immunity and metabolism. Mitochondria also play a key role in the buffering of cytosolic calcium, and calcium transported into the matrix regulates mitochondrial metabolism. Recently, the identification of the mitochondrial calcium uniporter (MCU) and associated regulators has allowed the characterization of new physiological roles for calcium in both mitochondrial and cellular homeostasis. Indeed, recent work has highlighted the importance of mitochondrial calcium homeostasis in regulating cell migration. Cell migration is a property common to all metazoans and is critical to embryogenesis, cancer progression, wound-healing and immune surveillance. Previous work has established that cytoplasmic calcium is a key regulator of cell migration, as oscillations in cytosolic calcium activate cytoskeletal remodelling, actin contraction and focal adhesion (FA) turnover necessary for cell movement. Recent work using animal models and in cellulo experiments to genetically modulate MCU and partners have shed new light on the role of mitochondrial calcium dynamics in cytoskeletal remodelling through the modulation of ATP and ROS production, as well as intracellular calcium signalling. This review focuses on MCU and its regulators in cell migration during physiological and pathophysiological processes including development and cancer. We also present hypotheses to explain the molecular mechanisms by which MCU may regulate mitochondrial dynamics and motility to drive cell migration.
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Affiliation(s)
- Vincent Paupe
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
| | - Julien Prudent
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom.
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34
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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: 114] [Impact Index Per Article: 19.0] [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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35
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Rorsman P, Ashcroft FM. Pancreatic β-Cell Electrical Activity and Insulin Secretion: Of Mice and Men. Physiol Rev 2018; 98:117-214. [PMID: 29212789 PMCID: PMC5866358 DOI: 10.1152/physrev.00008.2017] [Citation(s) in RCA: 433] [Impact Index Per Article: 72.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/30/2017] [Accepted: 06/18/2017] [Indexed: 12/14/2022] Open
Abstract
The pancreatic β-cell plays a key role in glucose homeostasis by secreting insulin, the only hormone capable of lowering the blood glucose concentration. Impaired insulin secretion results in the chronic hyperglycemia that characterizes type 2 diabetes (T2DM), which currently afflicts >450 million people worldwide. The healthy β-cell acts as a glucose sensor matching its output to the circulating glucose concentration. It does so via metabolically induced changes in electrical activity, which culminate in an increase in the cytoplasmic Ca2+ concentration and initiation of Ca2+-dependent exocytosis of insulin-containing secretory granules. Here, we review recent advances in our understanding of the β-cell transcriptome, electrical activity, and insulin exocytosis. We highlight salient differences between mouse and human β-cells, provide models of how the different ion channels contribute to their electrical activity and insulin secretion, and conclude by discussing how these processes become perturbed in T2DM.
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Affiliation(s)
- Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Frances M Ashcroft
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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Impaired mitochondrial calcium uptake caused by tacrolimus underlies beta-cell failure. Cell Commun Signal 2017; 15:47. [PMID: 29132395 PMCID: PMC5684747 DOI: 10.1186/s12964-017-0203-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/02/2017] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND One of the most common side effects of the immunosuppressive drug tacrolimus (FK506) is the increased risk of new-onset diabetes mellitus. However, the molecular mechanisms underlying this association have not been fully clarified. METHODS We studied the effects of the therapeutic dose of tacrolimus on mitochondrial fitness in beta-cells. RESULTS We demonstrate that tacrolimus impairs glucose-stimulated insulin secretion (GSIS) in beta-cells through a previously unidentified mechanism. Indeed, tacrolimus causes a decrease in mitochondrial Ca2+ uptake, accompanied by altered mitochondrial respiration and reduced ATP production, eventually leading to impaired GSIS. CONCLUSION Our observations individuate a new fundamental mechanism responsible for the augmented incidence of diabetes following tacrolimus treatment. Indeed, this drug alters Ca2+ fluxes in mitochondria, thereby compromising metabolism-secretion coupling in beta-cells.
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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: 71] [Impact Index Per Article: 10.1] [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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38
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Rutter GA, Hodson DJ, Chabosseau P, Haythorne E, Pullen TJ, Leclerc I. Local and regional control of calcium dynamics in the pancreatic islet. Diabetes Obes Metab 2017; 19 Suppl 1:30-41. [PMID: 28466490 DOI: 10.1111/dom.12990] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 04/19/2017] [Accepted: 04/24/2017] [Indexed: 12/31/2022]
Abstract
Ca2+ is the key intracellular regulator of insulin secretion, acting in the β-cell as the ultimate trigger for exocytosis. In response to high glucose, ATP-sensitive K+ channel closure and plasma membrane depolarization engage a sophisticated machinery to drive pulsatile cytosolic Ca2+ changes. Voltage-gated Ca2+ channels, Ca2+ -activated K+ channels and Na+ /Ca2+ exchange all play important roles. The use of targeted Ca2+ probes has revealed that during each cytosolic Ca2+ pulse, uptake of Ca2+ by mitochondria, endoplasmic reticulum (ER), secretory granules and lysosomes fine-tune cytosolic Ca2+ dynamics and control organellar function. For example, changes in the expression of the Ca2+ -binding protein Sorcin appear to provide a link between ER Ca2+ levels and ER stress, affecting β-cell function and survival. Across the islet, intercellular communication between highly interconnected "hubs," which act as pacemaker β-cells, and subservient "followers," ensures efficient insulin secretion. Loss of connectivity is seen after the deletion of genes associated with type 2 diabetes (T2D) and follows metabolic and inflammatory insults that characterize this disease. Hubs, which typically comprise ~1%-10% of total β-cells, are repurposed for their specialized role by expression of high glucokinase (Gck) but lower Pdx1 and Nkx6.1 levels. Single cell-omics are poised to provide a deeper understanding of the nature of these cells and of the networks through which they communicate. New insights into the control of both the intra- and intercellular Ca2+ dynamics may thus shed light on T2D pathology and provide novel opportunities for therapy.
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Affiliation(s)
- Guy A Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Edgbaston, UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, COMPARE University of Birmingham and University of Nottingham Midlands, Birmingham, UK
| | - Pauline Chabosseau
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
| | - Elizabeth Haythorne
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
| | - Timothy J Pullen
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
| | - Isabelle Leclerc
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
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39
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Pelosse M, Cottet-Rousselle C, Grichine A, Berger I, Schlattner U. Genetically Encoded Fluorescent Biosensors to Explore AMPK Signaling and Energy Metabolism. ACTA ACUST UNITED AC 2017; 107:491-523. [PMID: 27812993 DOI: 10.1007/978-3-319-43589-3_20] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Maintenance of energy homeostasis is a basic requirement for cell survival. Different mechanisms have evolved to cope with spatial and temporal mismatch between energy-providing and -consuming processes. Among these, signaling by AMP-activated protein kinase (AMPK) is one of the key players, regulated by and itself regulating cellular adenylate levels. Further understanding its complex cellular function requires deeper insight into its activation patterns in space and time at a single cell level. This may become possible with an increasing number of genetically encoded fluorescent biosensors, mostly based on fluorescence resonance energy transfer, which have been engineered to monitor metabolic parameters and kinase activities. Here, we review basic principles of biosensor design and function and the advantages and limitations of their use and provide an overview on existing FRET biosensors to monitor AMPK activation, ATP concentration, and ATP/ADP ratios, together with other key metabolites and parameters of energy metabolism.
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Affiliation(s)
- Martin Pelosse
- Laboratory of Fundamental and Applied Bioenergetics (LBFA) and SFR Environmental and Systems Biology (BEeSy), University Grenoble Alpes, Grenoble, France.,Inserm, U1055 and U1209, Grenoble, France
| | - Cécile Cottet-Rousselle
- Laboratory of Fundamental and Applied Bioenergetics (LBFA) and SFR Environmental and Systems Biology (BEeSy), University Grenoble Alpes, Grenoble, France.,Inserm, U1055 and U1209, Grenoble, France
| | - Alexei Grichine
- Inserm, U1055 and U1209, Grenoble, France.,Institute for Advanced Biosciences, University Grenoble Alpes, Grenoble, France
| | | | - Uwe Schlattner
- Laboratory of Fundamental and Applied Bioenergetics (LBFA) and SFR Environmental and Systems Biology (BEeSy), University Grenoble Alpes, Grenoble, France. .,Inserm, U1055 and U1209, Grenoble, France.
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40
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Dong Z, Zhao P, Xu M, Zhang C, Guo W, Chen H, Tian J, Wei H, Lu R, Cao T. Astragaloside IV alleviates heart failure via activating PPARα to switch glycolysis to fatty acid β-oxidation. Sci Rep 2017; 7:2691. [PMID: 28578382 PMCID: PMC5457407 DOI: 10.1038/s41598-017-02360-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 04/10/2017] [Indexed: 01/01/2023] Open
Abstract
In heart failure (HF), energy metabolism pathway in cardiac muscle changes from fatty acid β-oxidation to glycolysis. However, the exact mechanism is unknown. Sarcoendoplasmic reticulum Ca2+α ATPase (SERCA) expression is downregulated and mitochondrial function is reduced in HF, perhaps partly due to a substantially reduced energy supply for excitation–contraction coupling resulting from a lower fatty acid β-oxidation rate. We investigated whether Astragaloside IV can activate peroxisome proliferator-activated receptor alpha (PPARα) to stimulate fatty acid β-oxidation and increase cardiac energy production, improving mitochondrial function and the efficiency of SERCA in HF. In pressure overload-induced HF mice and isolated hypertrophic myocardial cells, fatty acid β-oxidation and heart function were substantially strengthened following Astragaloside IV treatment, as demonstrated by the increased expression of PPARα and SERCA2a. In vitro, Astragaloside IV regulated energy metabolism by increasing ATP production and enhancing mitochondrial function, attributable to increased oxygen consumption and slightly increased mitochondrial Ca2+ uptake. In HF, Astragaloside IV switched glycolysis to fatty acid β-oxidation, as confirmed by reduced anaerobic glycolysis and an increased oxygen consumption ratio. These results suggest that Astragaloside IV can stimulate fatty acid β-oxidation and improve mitochondrial function, which may present a novel cardioprotective treatment that inhibits the progress of HF.
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Affiliation(s)
- Zhiwei Dong
- Institute of Burn Research, Southwest Hospital, State Key Laboratory of Trauma, Burns and Combined Injury, Third Military Medical University, Chongqing, 400038, China
| | - Pei Zhao
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China
| | - Ming Xu
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China
| | - Chen Zhang
- Division of Cardiothoracic Surgery, Baylor college of medicine, Houston, Texas, USA
| | - Wei Guo
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China
| | - Huihua Chen
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China
| | - Jing Tian
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China
| | - Hongchang Wei
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China
| | - Rong Lu
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China.
| | - Tongtong Cao
- Department of Pathology, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai, 201203, China.
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41
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Abstract
The pancreatic β-cell secretes insulin in response to elevated plasma glucose. This review applies an external bioenergetic critique to the central processes of glucose-stimulated insulin secretion, including glycolytic and mitochondrial metabolism, the cytosolic adenine nucleotide pool, and its interaction with plasma membrane ion channels. The control mechanisms responsible for the unique responsiveness of the cell to glucose availability are discussed from bioenergetic and metabolic control standpoints. The concept of coupling factor facilitation of secretion is critiqued, and an attempt is made to unravel the bioenergetic basis of the oscillatory mechanisms controlling secretion. The need to consider the physiological constraints operating in the intact cell is emphasized throughout. The aim is to provide a coherent pathway through an extensive, complex, and sometimes bewildering literature, particularly for those unfamiliar with the field.
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Affiliation(s)
- David G Nicholls
- Buck Institute for Research on Aging, Novato, California; and Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmo, Sweden
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42
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Gerber PA, Rutter GA. The Role of Oxidative Stress and Hypoxia in Pancreatic Beta-Cell Dysfunction in Diabetes Mellitus. Antioxid Redox Signal 2017; 26:501-518. [PMID: 27225690 PMCID: PMC5372767 DOI: 10.1089/ars.2016.6755] [Citation(s) in RCA: 385] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 05/25/2016] [Indexed: 12/16/2022]
Abstract
SIGNIFICANCE Metabolic syndrome is a frequent precursor of type 2 diabetes mellitus (T2D), a disease that currently affects ∼8% of the adult population worldwide. Pancreatic beta-cell dysfunction and loss are central to the disease process, although understanding of the underlying molecular mechanisms is still fragmentary. Recent Advances: Oversupply of nutrients, including glucose and fatty acids, and the subsequent overstimulation of beta cells, are believed to be an important contributor to insulin secretory failure in T2D. Hypoxia has also recently been implicated in beta-cell damage. Accumulating evidence points to a role for oxidative stress in both processes. Although the production of reactive oxygen species (ROS) results from enhanced mitochondrial respiration during stimulation with glucose and other fuels, the expression of antioxidant defense genes is unusually low (or disallowed) in beta cells. CRITICAL ISSUES Not all subjects with metabolic syndrome and hyperglycemia go on to develop full-blown diabetes, implying an important role in disease risk for gene-environment interactions. Possession of common risk alleles at the SLC30A8 locus, encoding the beta-cell granule zinc transporter ZnT8, may affect cytosolic Zn2+ concentrations and thus susceptibility to hypoxia and oxidative stress. FUTURE DIRECTIONS Loss of normal beta-cell function, rather than total mass, is increasingly considered to be the major driver for impaired insulin secretion in diabetes. Better understanding of the role of oxidative changes, its modulation by genes involved in disease risk, and effects on beta-cell identity may facilitate the development of new therapeutic strategies to this disease. Antioxid. Redox Signal. 26, 501-518.
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Affiliation(s)
- Philipp A. Gerber
- Department of Endocrinology, Diabetes and Clinical Nutrition, University Hospital Zurich, Zurich, Switzerland
| | - Guy A. Rutter
- Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial College London, London, United Kingdom
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43
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Morris G, Walder K, McGee SL, Dean OM, Tye SJ, Maes M, Berk M. A model of the mitochondrial basis of bipolar disorder. Neurosci Biobehav Rev 2017; 74:1-20. [DOI: 10.1016/j.neubiorev.2017.01.014] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 01/08/2017] [Accepted: 01/10/2017] [Indexed: 12/11/2022]
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44
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McKenna JP, Ha J, Merrins MJ, Satin LS, Sherman A, Bertram R. Ca2+ Effects on ATP Production and Consumption Have Regulatory Roles on Oscillatory Islet Activity. Biophys J 2017; 110:733-742. [PMID: 26840737 DOI: 10.1016/j.bpj.2015.11.3526] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 10/21/2015] [Accepted: 11/06/2015] [Indexed: 11/19/2022] Open
Abstract
Pancreatic islets respond to elevated blood glucose by secreting pulses of insulin that parallel oscillations in β-cell metabolism, intracellular Ca(2+) concentration, and bursting electrical activity. The mechanisms that maintain an oscillatory response are not fully understood, yet several models have been proposed. Only some can account for experiments supporting that metabolism is intrinsically oscillatory in β-cells. The dual oscillator model (DOM) implicates glycolysis as the source of oscillatory metabolism. In the companion article, we use recently developed biosensors to confirm that glycolysis is oscillatory and further elucidate the coordination of metabolic and electrical signals in the insulin secretory pathway. In this report, we modify the DOM by incorporating an established link between metabolism and intracellular Ca(2+) to reconcile model predictions with experimental observations from the companion article. With modification, we maintain the distinguishing feature of the DOM, oscillatory glycolysis, but introduce the ability of Ca(2+) influx to reshape glycolytic oscillations by promoting glycolytic efflux. We use the modified model to explain measurements from the companion article and from previously published experiments with islets.
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Affiliation(s)
- Joseph P McKenna
- Department of Mathematics, Florida State University, Tallahassee, Florida
| | - Joon Ha
- Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Matthew J Merrins
- Division of Endocrinology, Diabetes & Metabolism, Department of Medicine and Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin; William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin
| | - Leslie S Satin
- Department of Pharmacology and Brehm Diabetes Center, University of Michigan, Ann Arbor, Michigan
| | - Arthur Sherman
- Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Richard Bertram
- Department of Mathematics, Florida State University, Tallahassee, Florida; Programs in Neuroscience and Molecular Biophysics, Florida State University, Tallahassee, Florida.
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45
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Merrins MJ, Poudel C, McKenna JP, Ha J, Sherman A, Bertram R, Satin LS. Phase Analysis of Metabolic Oscillations and Membrane Potential in Pancreatic Islet β-Cells. Biophys J 2017; 110:691-699. [PMID: 26840733 DOI: 10.1016/j.bpj.2015.12.029] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 12/17/2015] [Accepted: 12/22/2015] [Indexed: 01/01/2023] Open
Abstract
Metabolism in islet β-cells displays oscillations that can trigger pulses of electrical activity and insulin secretion. There has been a decades-long debate among islet biologists about whether metabolic oscillations are intrinsic or occur in response to oscillations in intracellular Ca(2+) that result from bursting electrical activity. In this article, the dynamics of oscillatory metabolism were investigated using five different optical reporters. Reporter activity was measured simultaneously with membrane potential bursting to determine the phase relationships between the metabolic oscillations and electrical activity. Our experimental findings suggest that Ca(2+) entry into β-cells stimulates the rate of mitochondrial metabolism, accounting for the depletion of glycolytic intermediates during each oscillatory burst. We also performed Ca(2+) clamp tests in which we clamped membrane potential with the KATP channel-opener diazoxide and KCl to fix Ca(2+) at an elevated level. These tests confirm that metabolic oscillations do not require Ca(2+) oscillations, but show that Ca(2+) plays a larger role in shaping metabolic oscillations than previously suspected. A dynamical picture of the mechanisms of oscillations emerged that requires the restructuring of contemporary mathematical β-cell models, including our own dual oscillator model. In the companion article, we modified our model to account for these new data.
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Affiliation(s)
- Matthew J Merrins
- Division of Endocrinology, Diabetes & Metabolism, Department of Medicine and Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin; William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin
| | - Chetan Poudel
- Division of Endocrinology, Diabetes & Metabolism, Department of Medicine and Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin; William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin
| | - Joseph P McKenna
- Department of Mathematics and Programs in Neuroscience and Molecular Biophysics, Florida State University, Tallahassee, Florida
| | - Joon Ha
- Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Arthur Sherman
- Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Richard Bertram
- Department of Mathematics and Programs in Neuroscience and Molecular Biophysics, Florida State University, Tallahassee, Florida
| | - Leslie S Satin
- Department of Pharmacology and Brehm Diabetes Center, University of Michigan, Ann Arbor, Michigan.
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46
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Mitochondrial Calcium Handling in Physiology and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 982:25-47. [PMID: 28551780 DOI: 10.1007/978-3-319-55330-6_2] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Calcium (Ca2+) accumulation inside mitochondria represents a pleiotropic signal controlling a wide range of cellular functions, including key metabolic pathways and life/death decisions. This phenomenon has been first described in the 1960s, but the identity of the molecules controlling this process remained a mystery until just few years ago, when both mitochondrial Ca2+ uptake and release systems were genetically dissected. This finally opened the possibility to develop genetic models to directly test the contribution of mitochondrial Ca2+ homeostasis to cellular functions. Here we summarize our current understanding of the molecular machinery that controls mitochondrial Ca2+ handling and critically evaluate the physiopathological role of mitochondrial Ca2+ signaling, based on recent evidences obtained through in vitro and in vivo models.
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47
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Abstract
In the last 5 years, most of the molecules that control mitochondrial Ca(2+) homeostasis have been finally identified. Mitochondrial Ca(2+) uptake is mediated by the Mitochondrial Calcium Uniporter (MCU) complex, a macromolecular structure that guarantees Ca(2+) accumulation inside mitochondrial matrix upon increases in cytosolic Ca(2+). Conversely, Ca(2+) release is under the control of the Na(+)/Ca(2+) exchanger, encoded by the NCLX gene, and of a H(+)/Ca(2+) antiporter, whose identity is still debated. The low affinity of the MCU complex, coupled to the activity of the efflux systems, protects cells from continuous futile cycles of Ca(2+) across the inner mitochondrial membrane and consequent massive energy dissipation. In this review, we discuss the basic principles that govern mitochondrial Ca(2+) homeostasis and the methods used to investigate the dynamics of Ca(2+) concentration within the organelles. We discuss the functional and structural role of the different molecules involved in mitochondrial Ca(2+) handling and their pathophysiological role.
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Affiliation(s)
- Diego De Stefani
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , ,
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , , .,National Research Council (CNR) Neuroscience Institute, 35121 Padova, Italy
| | - Tullio Pozzan
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , , .,National Research Council (CNR) Neuroscience Institute, 35121 Padova, Italy.,Venetian Institute of Molecular Medicine, 35121 Padova, Italy
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48
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Mammucari C, Raffaello A, Vecellio Reane D, Rizzuto R. Molecular structure and pathophysiological roles of the Mitochondrial Calcium Uniporter. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2457-64. [PMID: 26968367 DOI: 10.1016/j.bbamcr.2016.03.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 02/24/2016] [Accepted: 03/01/2016] [Indexed: 01/21/2023]
Abstract
Mitochondrial Ca(2+) uptake regulates a wide array of cell functions, from stimulation of aerobic metabolism and ATP production in physiological settings, to induction of cell death in pathological conditions. The molecular identity of the Mitochondrial Calcium Uniporter (MCU), the highly selective channel responsible for Ca(2+) entry through the IMM, has been described less than five years ago. Since then, research has been conducted to clarify the modulation of its activity, which relies on the dynamic interaction with regulatory proteins, and its contribution to the pathophysiology of organs and tissues. Particular attention has been placed on characterizing the role of MCU in cardiac and skeletal muscles. In this review we summarize the molecular structure and regulation of the MCU complex in addition to its pathophysiological role, with particular attention to striated muscle tissues. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.
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Affiliation(s)
| | - Anna Raffaello
- Department of Biomedical Sciences, University of Padua, 35131, Italy.
| | | | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padua, 35131, Italy; Neuroscience Institute, National Research Council, Padua 35131, Italy.
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49
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Wacquier B, Combettes L, Van Nhieu GT, Dupont G. Interplay Between Intracellular Ca(2+) Oscillations and Ca(2+)-stimulated Mitochondrial Metabolism. Sci Rep 2016; 6:19316. [PMID: 26776859 PMCID: PMC4725975 DOI: 10.1038/srep19316] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 12/07/2015] [Indexed: 12/20/2022] Open
Abstract
Oscillations of cytosolic Ca(2+) concentration are a widespread mode of signalling. Oscillatory spikes rely on repetitive exchanges of Ca(2+) between the endoplasmic reticulum (ER) and the cytosol, due to the regulation of inositol 1,4,5-trisphosphate receptors. Mitochondria also sequester and release Ca(2+), thus affecting Ca(2+) signalling. Mitochondrial Ca(2+) activates key enzymes involved in ATP synthesis. We propose a new integrative model for Ca(2+) signalling and mitochondrial metabolism in electrically non-excitable cells. The model accounts for (1) the phase relationship of the Ca(2+) changes in the cytosol, the ER and mitochondria, (2) the dynamics of mitochondrial metabolites in response to cytosolic Ca(2+) changes, and (3) the impacts of cytosol/mitochondria Ca(2+) exchanges and of mitochondrial metabolism on Ca(2+) oscillations. Simulations predict that as expected, oscillations are slowed down by decreasing the rate of Ca(2+) efflux from mitochondria, but also by decreasing the rate of Ca(2+) influx through the mitochondrial Ca(2+) uniporter (MCU). These predictions were experimentally validated by inhibiting MCU expression. Despite the highly non-linear character of Ca(2+) dynamics and mitochondrial metabolism, bioenergetics were found to be robust with respect to changes in frequency and amplitude of Ca(2+) oscillations.
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Affiliation(s)
- Benjamin Wacquier
- Unité de Chronobiologie Théorique, Université Libre de Bruxelles, CP231, Boulevard du Triomphe, 1050, Brussels, Belgium
| | - Laurent Combettes
- Université Paris Sud, UMRS1174, Orsay F-91405, France.,Institut National de la Santé et de la Recherche Médicale (Inserm), UMRS1174, Orsay F-91405, France
| | - Guy Tran Van Nhieu
- Equipe Communication Intercellulaire et Infections Microbiennes, Centre de Recherche Interdisciplinaire en Biologie(CIRB), Collège de France, 11 Place Marcelin Berthelot, Paris 75005, France.,Inserm, U1050, Paris 75005, France.,Centre national de la Recherche Scientifique (CNRS), UMR7241, Paris 75005, France.,MEMOLIFE Laboratory of excellence and Paris Sciences et Lettres, Paris 75005, France
| | - Geneviève Dupont
- Unité de Chronobiologie Théorique, Université Libre de Bruxelles, CP231, Boulevard du Triomphe, 1050, Brussels, Belgium
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50
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Abstract
The mitochondrial calcium uniporter is an evolutionarily conserved calcium channel, and its biophysical properties and relevance to cell death, bioenergetics and signalling have been investigated for decades. However, the genes encoding this channel have only recently been discovered, opening up a new 'molecular era' in the study of its biology. We now know that the uniporter is not a single protein but rather a macromolecular complex consisting of pore-forming and regulatory subunits. We review recent studies that harnessed the power of molecular biology and genetics to characterize the mechanism of action of the uniporter, its evolution and its contribution to physiology and human disease.
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