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Gottschalk B, Koshenov Z, Malli R, Graier WF. Implications of mitochondrial membrane potential gradients on signaling and ATP production analyzed by correlative multi-parameter microscopy. Sci Rep 2024; 14:14784. [PMID: 38926476 PMCID: PMC11208492 DOI: 10.1038/s41598-024-65595-z] [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: 02/20/2024] [Accepted: 06/21/2024] [Indexed: 06/28/2024] Open
Abstract
The complex architecture and biochemistry of the inner mitochondrial membrane generate ultra-structures with different phospholipid and protein compositions, shapes, characteristics, and functions. The crista junction (CJ) serves as an important barrier separating the cristae (CM) and inner boundary membranes (IBM). Thereby CJ regulates the movement of ions and ensures distinct electrical potentials across the cristae (ΔΨC) and inner boundary (ΔΨIBM) membranes. We have developed a robust and flexible approach to visualize the CJ permeability with super-resolution microscopy as a readout of local mitochondrial membrane potential (ΔΨmito) fluctuations. This method involves analyzing the distribution of TMRM fluorescence intensity in a model that is restricted to the mitochondrial geometry. We show that mitochondrial Ca2+ elevation hyperpolarizes the CM most likely caused by Ca2+ sensitive increase of mitochondrial tricarboxylic acid cycle (TCA) and subsequent oxidative phosphorylation (OXPHOS) activity in the cristae. Dynamic multi-parameter correlation measurements of spatial mitochondrial membrane potential gradients, ATP levels, and mitochondrial morphometrics revealed a CJ-based membrane potential overflow valve mechanism protecting the mitochondrial integrity during excessive cristae hyperpolarization.
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Affiliation(s)
- Benjamin Gottschalk
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010, Graz, Austria
| | - Zhanat Koshenov
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010, Graz, Austria
| | - Roland Malli
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010, Graz, Austria
- BioTechMed, Graz, Austria
| | - Wolfgang F Graier
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010, Graz, Austria.
- BioTechMed, Graz, Austria.
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2
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Cadile F, Recchia D, Ansaldo M, Rossi P, Rastelli G, Boncompagni S, Brocca L, Pellegrino MA, Canepari M. Diaphragm Fatigue in SMNΔ7 Mice and Its Molecular Determinants: An Underestimated Issue. Int J Mol Sci 2023; 24:14953. [PMID: 37834400 PMCID: PMC10574014 DOI: 10.3390/ijms241914953] [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: 09/11/2023] [Revised: 09/29/2023] [Accepted: 10/03/2023] [Indexed: 10/15/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a genetic disorder characterized by the loss of spinal motor neurons leading to muscle weakness and respiratory failure. Mitochondrial dysfunctions are found in the skeletal muscle of patients with SMA. For obvious ethical reasons, the diaphragm muscle is poorly studied, notwithstanding the very important role that respiratory involvement plays in SMA mortality. The main goal of this study was to investigate diaphragm functionality and the underlying molecular adaptations in SMNΔ7 mice, a mouse model that exhibits symptoms similar to that of patients with intermediate type II SMA. Functional, biochemical, and molecular analyses on isolated diaphragm were performed. The obtained results suggest the presence of an intrinsic energetic imbalance associated with mitochondrial dysfunction and a significant accumulation of reactive oxygen species (ROS). In turn, ROS accumulation can affect muscle fatigue, cause diaphragm wasting, and, in the long run, respiratory failure in SMNΔ7 mice. Exposure to the antioxidant molecule ergothioneine leads to the functional recovery of the diaphragm, confirming the presence of mitochondrial impairment and redox imbalance. These findings suggest the possibility of carrying out a dietary supplementation in SMNΔ7 mice to preserve their diaphragm function and increase their lifespan.
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Affiliation(s)
- Francesca Cadile
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
| | - Deborah Recchia
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (D.R.); (P.R.)
| | - Massimiliano Ansaldo
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
| | - Paola Rossi
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (D.R.); (P.R.)
| | - Giorgia Rastelli
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, 66100 Chieti, Italy; (G.R.); (S.B.)
| | - Simona Boncompagni
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, 66100 Chieti, Italy; (G.R.); (S.B.)
- Department of Neuroscience, Imaging and Clinical Sciences, University G. d’Annunzio of Chieti-Pescara, 66100 Chieti, Italy
| | - Lorenza Brocca
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
| | - Maria Antonietta Pellegrino
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
| | - Monica Canepari
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
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3
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Protasi F, Girolami B, Roccabianca S, Rossi D. Store-operated calcium entry: From physiology to tubular aggregate myopathy. Curr Opin Pharmacol 2023; 68:102347. [PMID: 36608411 DOI: 10.1016/j.coph.2022.102347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 11/30/2022] [Accepted: 12/04/2022] [Indexed: 01/06/2023]
Abstract
Store-Operated Ca2+ entry (SOCE) is recognized as a key mechanism in muscle physiology necessary to refill intracellular Ca2+ stores during sustained muscle activity. For many years the cell structures expected to mediate SOCE in skeletal muscle fibres remained unknown. Recently, the identification of Ca2+ Entry Units (CEUs) in exercised muscle fibres opened new insights into the role of extracellular Ca2+ in muscle contraction and, more generally, in intracellular Ca2+ homeostasis. Accordingly, intracellular Ca2+ unbalance due to alterations in SOCE strictly correlates with muscle disfunction and disease. Mutations in proteins involved in SOCE (STIM1, ORAI1, and CASQ1) have been linked to tubular aggregate myopathy (TAM), a disease that causes muscle weakness and myalgia and is characterized by a typical accumulation of highly ordered and packed membrane tubules originated from the sarcoplasmic reticulum (SR). Achieving a full understanding of the molecular pathways activated by alterations in Ca2+ entry mechanisms is a necessary step to design effective therapies for human SOCE-related disorders.
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Affiliation(s)
- Feliciano Protasi
- CAST, Center for Advanced Studies and Technology; University G. d'Annunzio of Chieti-Pescara, I-66100, Italy; DMSI, Department of Medicine and Aging Sciences; University G. d'Annunzio of Chieti-Pescara, I-66100, Italy
| | - Barbara Girolami
- CAST, Center for Advanced Studies and Technology; University G. d'Annunzio of Chieti-Pescara, I-66100, Italy; DMSI, Department of Medicine and Aging Sciences; University G. d'Annunzio of Chieti-Pescara, I-66100, Italy
| | - Sara Roccabianca
- DMMS, Department of Molecular and Developmental Medicine; University of Siena, I-53100, Siena Italy
| | - Daniela Rossi
- DMMS, Department of Molecular and Developmental Medicine; University of Siena, I-53100, Siena Italy.
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4
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Gineste C, Youhanna S, Vorrink SU, Henriksson S, Hernández A, Cheng AJ, Chaillou T, Buttgereit A, Schneidereit D, Friedrich O, Hultenby K, Bruton JD, Ivarsson N, Sandblad L, Lauschke VM, Westerblad H. Enzymatically dissociated muscle fibers display rapid dedifferentiation and impaired mitochondrial calcium control. iScience 2022; 25:105654. [PMID: 36479146 PMCID: PMC9720020 DOI: 10.1016/j.isci.2022.105654] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 07/19/2022] [Accepted: 11/18/2022] [Indexed: 11/23/2022] Open
Abstract
Cells rapidly lose their physiological phenotype upon disruption of their extracellular matrix (ECM)-intracellular cytoskeleton interactions. By comparing adult mouse skeletal muscle fibers, isolated either by mechanical dissection or by collagenase-induced ECM digestion, we investigated acute effects of ECM disruption on cellular and mitochondrial morphology, transcriptomic signatures, and Ca2+ handling. RNA-sequencing showed striking differences in gene expression patterns between the two isolation methods with enzymatically dissociated fibers resembling myopathic phenotypes. Mitochondrial appearance was grossly similar in the two groups, but 3D electron microscopy revealed shorter and less branched mitochondria following enzymatic dissociation. Repeated contractions resulted in a prolonged mitochondrial Ca2+ accumulation in enzymatically dissociated fibers, which was partially prevented by cyclophilin inhibitors. Of importance, muscle fibers of mice with severe mitochondrial myopathy show pathognomonic mitochondrial Ca2+ accumulation during repeated contractions and this accumulation was concealed with enzymatic dissociation, making this an ambiguous method in studies of native intracellular Ca2+ fluxes.
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Affiliation(s)
- Charlotte Gineste
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Sonia Youhanna
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Sabine U. Vorrink
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Sara Henriksson
- Umeå Core Facility for Electron Microscopy, Department of Chemistry, Umeå University, 901 87 Umeå, Sweden
| | - Andrés Hernández
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Arthur J. Cheng
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Thomas Chaillou
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Andreas Buttgereit
- Institute of Medical Biotechnology, Department of Chemical and Biological Engineering, Friedrich-Alexander University of Erlangen-Nürnberg, 91052 Erlangen, Germany
| | - Dominik Schneidereit
- Institute of Medical Biotechnology, Department of Chemical and Biological Engineering, Friedrich-Alexander University of Erlangen-Nürnberg, 91052 Erlangen, Germany
| | - Oliver Friedrich
- Institute of Medical Biotechnology, Department of Chemical and Biological Engineering, Friedrich-Alexander University of Erlangen-Nürnberg, 91052 Erlangen, Germany
| | - Kjell Hultenby
- Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, 141 86 Huddinge, Sweden
| | - Joseph D. Bruton
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Niklas Ivarsson
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Linda Sandblad
- Umeå Core Facility for Electron Microscopy, Department of Chemistry, Umeå University, 901 87 Umeå, Sweden
| | - Volker M. Lauschke
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart, Germany
- University of Tübingen, Tübingen, Germany
| | - Håkan Westerblad
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
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5
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Senneff S, Lowery MM. Computational Model of the Effect of Mitochondrial Dysfunction on Excitation–Contraction Coupling in Skeletal Muscle. Bull Math Biol 2022; 84:123. [PMID: 36114931 PMCID: PMC9482608 DOI: 10.1007/s11538-022-01079-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 08/31/2022] [Indexed: 11/28/2022]
Abstract
It has become well established that mitochondria not only regulate myoplasmic calcium in skeletal muscle, but also use that calcium to stimulate oxidative phosphorylation (OXPHOS). While experimental approaches have allowed for imaging of mitochondrial calcium and membrane potentials in isolated fibers, capturing the role of mitochondria and the impact of mitochondrial impairments on excitation–contraction coupling (ECC) remains difficult to explore in intact muscle. Computational models have been widely used to examine the structure and function of skeletal muscle contraction; however, models of ECC to date lack communication between the myoplasm and mitochondria for regulating calcium and ATP during sustained contractions. To address this, a mathematical model of mitochondrial calcium handling and OXPHOS was integrated into a physiological model of ECC incorporating action potential propagation, calcium handling between the sarcoplasmic reticulum (SR) and the myoplasm, and crossbridge cycling. The model was used to examine the protective role of mitochondria during repeated stimulation and the impact of mitochondrial dysfunction on ECC resulting from progressive OXPHOS inhibition. Pathological myoplasmic calcium accumulation occurred through distinct mechanisms in the model in the case of either electron transport chain, F1F0 ATP synthase, or adenine nucleotide transporter impairments. To investigate the effect of each impairment on force, a model of calcium-stimulated apoptosis was utilized to capture dysfunction-induced reductions in muscle mass, driving whole muscle force loss. The model presented in this study can be used to examine the role of mitochondria in the regulation of calcium, ATP, and force generation during voluntary contraction.
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Affiliation(s)
- Sageanne Senneff
- School of Electrical and Electronic Engineering, University College Dublin, Belfield, Dublin 4, Ireland
| | - Madeleine M. Lowery
- School of Electrical and Electronic Engineering, University College Dublin, Belfield, Dublin 4, Ireland
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6
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Protasi F, Girolami B, Serano M, Pietrangelo L, Paolini C. Ablation of Calsequestrin-1, Ca 2+ unbalance, and susceptibility to heat stroke. Front Physiol 2022; 13:1033300. [PMID: 36311237 PMCID: PMC9598425 DOI: 10.3389/fphys.2022.1033300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 09/20/2022] [Indexed: 12/05/2022] Open
Abstract
Introduction: Ca2+ levels in adult skeletal muscle fibers are mainly controlled by excitation-contraction (EC) coupling, a mechanism that translates action potentials in release of Ca2+ from the sarcoplasmic reticulum (SR) release channels, i.e. the ryanodine receptors type-1 (RyR1). Calsequestrin (Casq) is a protein that binds large amounts of Ca2+ in the lumen of the SR terminal cisternae, near sites of Ca2+ release. There is general agreement that Casq is not only important for the SR ability to store Ca2+, but also for modulating the opening probability of the RyR Ca2+ release channels. The initial studies: About 20 years ago we generated a mouse model lacking Casq1 (Casq1-null mice), the isoform predominantly expressed in adult fast twitch skeletal muscle. While the knockout was not lethal as expected, lack of Casq1 caused a striking remodeling of membranes of SR and of transverse tubules (TTs), and mitochondrial damage. Functionally, CASQ1-knockout resulted in reduced SR Ca2+ content, smaller Ca2+ transients, and severe SR depletion during repetitive stimulation. The myopathic phenotype of Casq1-null mice: After the initial studies, we discovered that Casq1-null mice were prone to sudden death when exposed to halogenated anaesthetics, heat and even strenuous exercise. These syndromes are similar to human malignant hyperthermia susceptibility (MHS) and environmental-exertional heat stroke (HS). We learned that mechanisms underlying these syndromes involved excessive SR Ca2+ leak and excessive production of oxidative species: indeed, mortality and mitochondrial damage were significantly prevented by administration of antioxidants and reduction of oxidative stress. Though, how Casq1-null mice could survive without the most important SR Ca2+ binding protein was a puzzling issue that was not solved. Unravelling the mystery: The mystery was finally solved in 2020, when we discovered that in Casq1-null mice the SR undergoes adaptations that result in constitutively active store-operated Ca2+ entry (SOCE). SOCE is a mechanism that allows skeletal fibers to use external Ca2+ when SR stores are depleted. The post-natal compensatory mechanism that allows Casq1-null mice to survive involves the assembly of new SR-TT junctions (named Ca2+ entry units) containing Stim1 and Orai1, the two proteins that mediate SOCE.
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Affiliation(s)
- Feliciano Protasi
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
- Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
| | - Barbara Girolami
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
- Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
| | - Matteo Serano
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
- Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
| | - Laura Pietrangelo
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
- Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
| | - Cecilia Paolini
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
- Department of Neuroscience, Imaging and Clinical Sciences, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
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7
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Eshima H. Influence of Obesity and Type 2 Diabetes on Calcium Handling by Skeletal Muscle: Spotlight on the Sarcoplasmic Reticulum and Mitochondria. Front Physiol 2021; 12:758316. [PMID: 34795598 PMCID: PMC8592904 DOI: 10.3389/fphys.2021.758316] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 10/14/2021] [Indexed: 12/25/2022] Open
Abstract
Obesity and diabetes have been shown to interfere with energy metabolism and cause peripheral insulin resistance in skeletal muscle. However, recent studies have focused on the effect metabolic insult has on the loss of muscle size, strength, and physical function. Contractile dysfunction has been linked to impaired intracellular Ca2+ concentration ([Ca2+]i) regulation. In skeletal muscle, [Ca2+]i homeostasis is highly regulated by Ca2+ transport across the sarcolemma/plasma membrane, the golgi apparatus, sarcoplasmic reticulum (SR), and mitochondria. Particularly, the SR and or mitochondria play an important role in the fine-tuning of this metabolic process. Recent studies showed that obesity and insulin resistance are associated with interactions between the SR and mitochondrial networks (the dynamic tubular reticulum formed by mitochondria), suggesting that metabolic disorders alter Ca2+ handling by these organelles. These interactions are facilitated by specific membrane proteins, including ion channels. This review considers the impact of metabolic disorders, such as obesity and type 2 diabetes, on the regulation of [Ca2+]i in skeletal muscle. It also discusses the mechanisms by which this occurs, focusing chiefly on the SR and mitochondria networks. A deeper understanding of the effect of metabolic disorders on calcium handling might be useful for therapeutic strategies.
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Affiliation(s)
- Hiroaki Eshima
- Department of International Tourism, Nagasaki International University, Nagasaki, Japan
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8
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Calsequestrin 1 Is an Active Partner of Stromal Interaction Molecule 2 in Skeletal Muscle. Cells 2021; 10:cells10112821. [PMID: 34831044 PMCID: PMC8616366 DOI: 10.3390/cells10112821] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/13/2021] [Accepted: 10/19/2021] [Indexed: 12/25/2022] Open
Abstract
Calsequestrin 1 (CASQ1) in skeletal muscle buffers and senses Ca2+ in the sarcoplasmic reticulum (SR). CASQ1 also regulates store-operated Ca2+ entry (SOCE) by binding to stromal interaction molecule 1 (STIM1). Abnormal SOCE and/or abnormal expression or mutations in CASQ1, STIM1, or STIM2 are associated with human skeletal, cardiac, or smooth muscle diseases. However, the functional relevance of CASQ1 along with STIM2 has not been studied in any tissue, including skeletal muscle. First, in the present study, it was found by biochemical approaches that CASQ1 is bound to STIM2 via its 92 N-terminal amino acids (C1 region). Next, to examine the functional relevance of the CASQ1-STIM2 interaction in skeletal muscle, the full-length wild-type CASQ1 or the C1 region was expressed in mouse primary skeletal myotubes, and the myotubes were examined using single-myotube Ca2+ imaging experiments and transmission electron microscopy observations. The CASQ1-STIM2 interaction via the C1 region decreased SOCE, increased intracellular Ca2+ release for skeletal muscle contraction, and changed intracellular Ca2+ distributions (high Ca2+ in the SR and low Ca2+ in the cytosol were observed). Furthermore, the C1 region itself (which lacks Ca2+-buffering ability but has STIM2-binding ability) decreased the expression of Ca2+-related proteins (canonical-type transient receptor potential cation channel type 6 and calmodulin 1) and induced mitochondrial shape abnormalities. Therefore, in skeletal muscle, CASQ1 plays active roles in Ca2+ movement and distribution by interacting with STIM2 as well as Ca2+ sensing and buffering.
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9
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Emery JM, Ortiz RM. Mitofusin 2: A link between mitochondrial function and substrate metabolism? Mitochondrion 2021; 61:125-137. [PMID: 34536562 DOI: 10.1016/j.mito.2021.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 08/22/2021] [Accepted: 09/13/2021] [Indexed: 01/18/2023]
Abstract
Mitochondria are dynamic, interactive organelles that connect cellular signaling and whole-cell homeostasis. This "mitochatting" allows the cell to receive information about the mitochondria's condition before accommodating energy demands. Mitofusin 2 (Mfn2), an outer mitochondrial membrane fusion protein specializes in mediating mitochondrial homeostasis. Early studies defined the biological significance of Mfn2, while latter studies highlighted its role in substrate metabolism. However, determining Mfn2 potential to contribute to energy homeostasis needs study. This review summarizes current literature on mitochondrial metabolic processes, dynamics, and evidence of interactions among Mfn2 and regulatory processes that may link Mfn2's role in maintaining mitochondrial function and substrate metabolism.
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Affiliation(s)
- Janna M Emery
- Department of Molecular and Cellular Biology, School of Natural Sciences, University of California, Merced, United States.
| | - Rudy M Ortiz
- Department of Molecular and Cellular Biology, School of Natural Sciences, University of California, Merced, United States
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10
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Michelucci A, Liang C, Protasi F, Dirksen RT. Altered Ca 2+ Handling and Oxidative Stress Underlie Mitochondrial Damage and Skeletal Muscle Dysfunction in Aging and Disease. Metabolites 2021; 11:metabo11070424. [PMID: 34203260 PMCID: PMC8304741 DOI: 10.3390/metabo11070424] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 06/22/2021] [Accepted: 06/24/2021] [Indexed: 12/26/2022] Open
Abstract
Skeletal muscle contraction relies on both high-fidelity calcium (Ca2+) signals and robust capacity for adenosine triphosphate (ATP) generation. Ca2+ release units (CRUs) are highly organized junctions between the terminal cisternae of the sarcoplasmic reticulum (SR) and the transverse tubule (T-tubule). CRUs provide the structural framework for rapid elevations in myoplasmic Ca2+ during excitation-contraction (EC) coupling, the process whereby depolarization of the T-tubule membrane triggers SR Ca2+ release through ryanodine receptor-1 (RyR1) channels. Under conditions of local or global depletion of SR Ca2+ stores, store-operated Ca2+ entry (SOCE) provides an additional source of Ca2+ that originates from the extracellular space. In addition to Ca2+, skeletal muscle also requires ATP to both produce force and to replenish SR Ca2+ stores. Mitochondria are the principal intracellular organelles responsible for ATP production via aerobic respiration. This review provides a broad overview of the literature supporting a role for impaired Ca2+ handling, dysfunctional Ca2+-dependent production of reactive oxygen/nitrogen species (ROS/RNS), and structural/functional alterations in CRUs and mitochondria in the loss of muscle mass, reduction in muscle contractility, and increase in muscle damage in sarcopenia and a wide range of muscle disorders including muscular dystrophy, rhabdomyolysis, central core disease, and disuse atrophy. Understanding the impact of these processes on normal muscle function will provide important insights into potential therapeutic targets designed to prevent or reverse muscle dysfunction during aging and disease.
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Affiliation(s)
- Antonio Michelucci
- DNICS, Department of Neuroscience, Imaging, and Clinical Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
- Correspondence:
| | - Chen Liang
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, NY 14642, USA; (C.L.); (R.T.D.)
| | - Feliciano Protasi
- CAST, Center for Advanced Studies and Technology, DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy;
| | - Robert T. Dirksen
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, NY 14642, USA; (C.L.); (R.T.D.)
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11
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Protasi F, Pietrangelo L, Boncompagni S. Improper Remodeling of Organelles Deputed to Ca 2+ Handling and Aerobic ATP Production Underlies Muscle Dysfunction in Ageing. Int J Mol Sci 2021; 22:6195. [PMID: 34201319 PMCID: PMC8228829 DOI: 10.3390/ijms22126195] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 12/28/2022] Open
Abstract
Proper skeletal muscle function is controlled by intracellular Ca2+ concentration and by efficient production of energy (ATP), which, in turn, depend on: (a) the release and re-uptake of Ca2+ from sarcoplasmic-reticulum (SR) during excitation-contraction (EC) coupling, which controls the contraction and relaxation of sarcomeres; (b) the uptake of Ca2+ into the mitochondrial matrix, which stimulates aerobic ATP production; and finally (c) the entry of Ca2+ from the extracellular space via store-operated Ca2+ entry (SOCE), a mechanism that is important to limit/delay muscle fatigue. Abnormalities in Ca2+ handling underlie many physio-pathological conditions, including dysfunction in ageing. The specific focus of this review is to discuss the importance of the proper architecture of organelles and membrane systems involved in the mechanisms introduced above for the correct skeletal muscle function. We reviewed the existing literature about EC coupling, mitochondrial Ca2+ uptake, SOCE and about the structural membranes and organelles deputed to those functions and finally, we summarized the data collected in different, but complementary, projects studying changes caused by denervation and ageing to the structure and positioning of those organelles: a. denervation of muscle fibers-an event that contributes, to some degree, to muscle loss in ageing (known as sarcopenia)-causes misplacement and damage: (i) of membrane structures involved in EC coupling (calcium release units, CRUs) and (ii) of the mitochondrial network; b. sedentary ageing causes partial disarray/damage of CRUs and of calcium entry units (CEUs, structures involved in SOCE) and loss/misplacement of mitochondria; c. functional electrical stimulation (FES) and regular exercise promote the rescue/maintenance of the proper architecture of CRUs, CEUs, and of mitochondria in both denervation and ageing. All these structural changes were accompanied by related functional changes, i.e., loss/decay in function caused by denervation and ageing, and improved function following FES or exercise. These data suggest that the integrity and proper disposition of intracellular organelles deputed to Ca2+ handling and aerobic generation of ATP is challenged by inactivity (or reduced activity); modifications in the architecture of these intracellular membrane systems may contribute to muscle dysfunction in ageing and sarcopenia.
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Affiliation(s)
- Feliciano Protasi
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy; (L.P.); (S.B.)
- DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
| | - Laura Pietrangelo
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy; (L.P.); (S.B.)
- DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
| | - Simona Boncompagni
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy; (L.P.); (S.B.)
- DNICS, Department of Neuroscience and Clinical Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
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12
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Carraro U, Yablonka-Reuveni Z. Translational research on Myology and Mobility Medicine: 2021 semi-virtual PDM3 from Thermae of Euganean Hills, May 26 - 29, 2021. Eur J Transl Myol 2021; 31:9743. [PMID: 33733717 PMCID: PMC8056169 DOI: 10.4081/ejtm.2021.9743] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 03/17/2021] [Indexed: 02/08/2023] Open
Abstract
On 19-21 November 2020, the meeting of the 30 years of the Padova Muscle Days was virtually held while the SARS-CoV-2 epidemic was hitting the world after a seemingly quiet summer. During the 2020-2021 winter, the epidemic is still active, despite the start of vaccinations. The organizers hope to hold the 2021 Padua Days on Myology and Mobility Medicine in a semi-virtual form (2021 S-V PDM3) from May 26 to May 29 at the Thermae of Euganean Hills, Padova, Italy. Here the program and the Collection of Abstracts are presented. Despite numerous world problems, the number of submitted/selected presentations (lectures and oral presentations) has increased, prompting the organizers to extend the program to four dense days.
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Affiliation(s)
- Ugo Carraro
- Department of Biomedical Sciences of the University of Padova, Italy; CIR-Myo - Myology Centre, University of Padova, Italy; A-C Mioni-Carraro Foundation for Translational Myology, Padova.
| | - Zipora Yablonka-Reuveni
- Department of Biological Structure, University of Washington School of Medicine, Seattle, WA.
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13
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Woo JS, Jeong SY, Park JH, Choi JH, Lee EH. Calsequestrin: a well-known but curious protein in skeletal muscle. Exp Mol Med 2020; 52:1908-1925. [PMID: 33288873 PMCID: PMC8080761 DOI: 10.1038/s12276-020-00535-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/14/2020] [Accepted: 10/19/2020] [Indexed: 12/23/2022] Open
Abstract
Calsequestrin (CASQ) was discovered in rabbit skeletal muscle tissues in 1971 and has been considered simply a passive Ca2+-buffering protein in the sarcoplasmic reticulum (SR) that provides Ca2+ ions for various Ca2+ signals. For the past three decades, physiologists, biochemists, and structural biologists have examined the roles of the skeletal muscle type of CASQ (CASQ1) in skeletal muscle and revealed that CASQ1 has various important functions as (1) a major Ca2+-buffering protein to maintain the SR with a suitable amount of Ca2+ at each moment, (2) a dynamic Ca2+ sensor in the SR that regulates Ca2+ release from the SR to the cytosol, (3) a structural regulator for the proper formation of terminal cisternae, (4) a reverse-directional regulator of extracellular Ca2+ entries, and (5) a cause of human skeletal muscle diseases. This review is focused on understanding these functions of CASQ1 in the physiological or pathophysiological status of skeletal muscle.
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Affiliation(s)
- Jin Seok Woo
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, 10833, USA
| | - Seung Yeon Jeong
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, 06591, Korea
- Department of Biomedicine & Health Sciences, Graduate School, The Catholic University of Korea, Seoul, 06591, Korea
| | - Ji Hee Park
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, 06591, Korea
- Department of Biomedicine & Health Sciences, Graduate School, The Catholic University of Korea, Seoul, 06591, Korea
| | - Jun Hee Choi
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, 06591, Korea
- Department of Biomedicine & Health Sciences, Graduate School, The Catholic University of Korea, Seoul, 06591, Korea
| | - Eun Hui Lee
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, 06591, Korea.
- Department of Biomedicine & Health Sciences, Graduate School, The Catholic University of Korea, Seoul, 06591, Korea.
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14
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Protasi F, Pietrangelo L, Boncompagni S. Calcium entry units (CEUs): perspectives in skeletal muscle function and disease. J Muscle Res Cell Motil 2020; 42:233-249. [PMID: 32812118 PMCID: PMC8332569 DOI: 10.1007/s10974-020-09586-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 08/03/2020] [Indexed: 12/28/2022]
Abstract
In the last decades the term Store-operated Ca2+ entry (SOCE) has been used in the scientific literature to describe an ubiquitous cellular mechanism that allows recovery of calcium (Ca2+) from the extracellular space. SOCE is triggered by a reduction of Ca2+ content (i.e. depletion) in intracellular stores, i.e. endoplasmic or sarcoplasmic reticulum (ER and SR). In skeletal muscle the mechanism is primarily mediated by a physical interaction between stromal interaction molecule-1 (STIM1), a Ca2+ sensor located in the SR membrane, and ORAI1, a Ca2+-permeable channel of external membranes, located in transverse tubules (TTs), the invaginations of the plasma membrane (PM) deputed to propagation of action potentials. It is generally accepted that in skeletal muscle SOCE is important to limit muscle fatigue during repetitive stimulation. We recently discovered that exercise promotes the assembly of new intracellular junctions that contains colocalized STIM1 and ORAI1, and that the presence of these new junctions increases Ca2+ entry via ORAI1, while improving fatigue resistance during repetitive stimulation. Based on these findings we named these new junctions Ca2+ Entry Units (CEUs). CEUs are dynamic organelles that assemble during muscle activity and disassemble during recovery thanks to the plasticity of the SR (containing STIM1) and the elongation/retraction of TTs (bearing ORAI1). Interestingly, similar structures described as SR stacks were previously reported in different mouse models carrying mutations in proteins involved in Ca2+ handling (calsequestrin-null mice; triadin and junctin null mice, etc.) or associated to microtubules (MAP6 knockout mice). Mutations in Stim1 and Orai1 (and calsequestrin-1) genes have been associated to tubular aggregate myopathy (TAM), a muscular disease characterized by: (a) muscle pain, cramping, or weakness that begins in childhood and worsens over time, and (b) the presence of large accumulations of ordered SR tubes (tubular aggregates, TAs) that do not contain myofibrils, mitochondria, nor TTs. Interestingly, TAs are also present in fast twitch muscle fibers of ageing mice. Several important issues remain un-answered: (a) the molecular mechanisms and signals that trigger the remodeling of membranes and the functional activation of SOCE during exercise are unclear; and (b) how dysfunctional SOCE and/or mutations in Stim1, Orai1 and calsequestrin (Casq1) genes lead to the formation of tubular aggregates (TAs) in aging and disease deserve investigation.
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Affiliation(s)
- Feliciano Protasi
- CAST, Center for Advanced Studies and Technology, University G. d'Annunzio of Chieti-Pescara, 66100, Chieti, Italy.
- DMSI, Department of Medicine and Aging Sciences, University G. d'Annunzio of Chieti-Pescara, 66100, Chieti, Italy.
| | - Laura Pietrangelo
- CAST, Center for Advanced Studies and Technology, University G. d'Annunzio of Chieti-Pescara, 66100, Chieti, Italy
- DMSI, Department of Medicine and Aging Sciences, University G. d'Annunzio of Chieti-Pescara, 66100, Chieti, Italy
| | - Simona Boncompagni
- CAST, Center for Advanced Studies and Technology, University G. d'Annunzio of Chieti-Pescara, 66100, Chieti, Italy
- DNICS, Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio of Chieti-Pescara, 66100, Chieti, Italy
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15
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Carraro U. Thirty years of translational research in Mobility Medicine: Collection of abstracts of the 2020 Padua Muscle Days. Eur J Transl Myol 2020; 30:8826. [PMID: 32499887 PMCID: PMC7254447 DOI: 10.4081/ejtm.2019.8826] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 01/22/2020] [Indexed: 12/11/2022] Open
Abstract
More than half a century of skeletal muscle research is continuing at Padua University (Italy) under the auspices of the Interdepartmental Research Centre of Myology (CIR-Myo), the European Journal of Translational Myology (EJTM) and recently also with the support of the A&CM-C Foundation for Translational Myology, Padova, Italy. The Volume 30(1), 2020 of the EJTM opens with the collection of abstracts for the conference "2020 Padua Muscle Days: Mobility Medicine 30 years of Translational Research". This is an international conference that will be held between March 18-21, 2020 in Euganei Hills and Padova in Italy. The abstracts are excellent examples of translational research and of the multidimensional approaches that are needed to classify and manage (in both the acute and chronic phases) diseases of Mobility that span from neurologic, metabolic and traumatic syndromes to the biological process of aging. One of the typical aim of Physical Medicine and Rehabilitation is indeed to reduce pain and increase mobility enough to enable impaired persons to walk freely, garden, and drive again. The excellent contents of this Collection of Abstracts reflect the high scientific caliber of researchers and clinicians who are eager to present their results at the PaduaMuscleDays. A series of EJTM Communications will also add to this preliminary evidence.
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Affiliation(s)
- Ugo Carraro
- Interdepartmental Research Centre of Myology (CIR-Myo), Department of Biomedical Sciences, University of Padova, Italy
- A&C M-C Foundation for Translational Myology, Padova, Italy
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16
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Sztretye M, Singlár Z, Szabó L, Angyal Á, Balogh N, Vakilzadeh F, Szentesi P, Dienes B, Csernoch L. Improved Tetanic Force and Mitochondrial Calcium Homeostasis by Astaxanthin Treatment in Mouse Skeletal Muscle. Antioxidants (Basel) 2020; 9:antiox9020098. [PMID: 31979219 PMCID: PMC7070261 DOI: 10.3390/antiox9020098] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Astaxanthin (AX) a marine carotenoid is a powerful natural antioxidant which protects against oxidative stress and improves muscle performance. Retinol and its derivatives were described to affect lipid and energy metabolism. Up to date, the effects of AX and retinol on excitation-contraction coupling (ECC) in skeletal muscle are poorly described. METHODS 18 C57Bl6 mice were divided into two groups: Control and AX supplemented in rodent chow for 4 weeks (AstaReal A1010). In vivo and in vitro force and intracellular calcium homeostasis was studied. In some experiments acute treatment with retinol was employed. RESULTS The voltage activation of calcium transients (V50) were investigated in single flexor digitorum brevis isolated fibers under patch clamp and no significant changes were found following AX supplementation. Retinol shifted V50 towards more positive values and decreased the peak F/F0 of the calcium transients. The amplitude of tetani in the extensor digitorum longus was significantly higher in AX than in control group. Lastly, the mitochondrial calcium uptake was found to be less prominent in AX. CONCLUSION AX supplementation increases in vitro tetanic force without affecting ECC and exerts a protecting effect on the mitochondria. Retinol treatment has an inhibitory effect on ECC in skeletal muscle.
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Affiliation(s)
- Mónika Sztretye
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.S.); (Z.S.); (L.S.); (Á.A.); (N.B.); (F.V.); (P.S.); (B.D.)
| | - Zoltán Singlár
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.S.); (Z.S.); (L.S.); (Á.A.); (N.B.); (F.V.); (P.S.); (B.D.)
- Doctoral School of Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - László Szabó
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.S.); (Z.S.); (L.S.); (Á.A.); (N.B.); (F.V.); (P.S.); (B.D.)
- Doctoral School of Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Ágnes Angyal
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.S.); (Z.S.); (L.S.); (Á.A.); (N.B.); (F.V.); (P.S.); (B.D.)
- Doctoral School of Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Norbert Balogh
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.S.); (Z.S.); (L.S.); (Á.A.); (N.B.); (F.V.); (P.S.); (B.D.)
- Doctoral School of Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Faranak Vakilzadeh
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.S.); (Z.S.); (L.S.); (Á.A.); (N.B.); (F.V.); (P.S.); (B.D.)
- Doctoral School of Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Péter Szentesi
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.S.); (Z.S.); (L.S.); (Á.A.); (N.B.); (F.V.); (P.S.); (B.D.)
| | - Beatrix Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.S.); (Z.S.); (L.S.); (Á.A.); (N.B.); (F.V.); (P.S.); (B.D.)
| | - László Csernoch
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.S.); (Z.S.); (L.S.); (Á.A.); (N.B.); (F.V.); (P.S.); (B.D.)
- Correspondence: ; Tel.: +36-52-255575; Fax: +36-52-255116
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17
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Lotteau S, Ivarsson N, Yang Z, Restagno D, Colyer J, Hopkins P, Weightman A, Himori K, Yamada T, Bruton J, Steele D, Westerblad H, Calaghan S. A Mechanism for Statin-Induced Susceptibility to Myopathy. JACC Basic Transl Sci 2019; 4:509-523. [PMID: 31468006 PMCID: PMC6712048 DOI: 10.1016/j.jacbts.2019.03.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 03/27/2019] [Accepted: 03/27/2019] [Indexed: 12/12/2022]
Abstract
This study aimed to identify a mechanism for statin-induced myopathy that explains its prevalence and selectivity for skeletal muscle, and to understand its interaction with moderate exercise. Statin-associated adverse muscle symptoms reduce adherence to statin therapy; this limits the effectiveness of statins in reducing cardiovascular risk. The issue is further compounded by perceived interactions between statin treatment and exercise. This study examined muscles from individuals taking statins and rats treated with statins for 4 weeks. In skeletal muscle, statin treatment caused dissociation of the stabilizing protein FK506 binding protein (FKBP12) from the sarcoplasmic reticulum (SR) calcium (Ca2+) release channel, the ryanodine receptor 1, which was associated with pro-apoptotic signaling and reactive nitrogen species/reactive oxygen species (RNS/ROS)-dependent spontaneous SR Ca2+ release events (Ca2+ sparks). Statin treatment had no effect on Ca2+ spark frequency in cardiac myocytes. Despite potentially deleterious effects of statins on skeletal muscle, there was no impact on force production or SR Ca2+ release in electrically stimulated muscle fibers. Statin-treated rats with access to a running wheel ran further than control rats; this exercise normalized FKBP12 binding to ryanodine receptor 1, preventing the increase in Ca2+ sparks and pro-apoptotic signaling. Statin-mediated RNS/ROS-dependent destabilization of SR Ca2+ handling has the potential to initiate skeletal (but not cardiac) myopathy in susceptible individuals. Importantly, although exercise increases RNS/ROS, it did not trigger deleterious statin effects on skeletal muscle. Indeed, our results indicate that moderate exercise might benefit individuals who take statins.
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Key Words
- Ca2+, calcium
- FDB, flexor digitorum brevis
- FKBP12, FK506 binding protein (calstabin)
- GAS, gastrocnemius
- HADHA, hydroxyacyl-CoA dehydrogenase/3-ketoacyl-CoA thiolase/enoyl-CoA hydratase
- HMG CoA, 3-hydroxy-3-methylglutaryl coenzyme A
- L-NAME, N(ω)-nitro-L-arginine methyl ester
- NOS, nitric oxide synthase
- PGC1α, peroxisome proliferator-activated receptor γ co-activator 1α
- RNS, reactive nitrogen species
- ROS, reactive oxygen species
- RyR, ryanodine receptor
- SOD, superoxide dismutase
- SR, sarcoplasmic reticulum
- TUNEL, terminal deoxynucleotidyl transferase dUTP nick end labeling
- calcium leak
- exercise
- myopathy
- ryanodine receptor
- statin
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Affiliation(s)
- Sabine Lotteau
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Niklas Ivarsson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Zhaokang Yang
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Damien Restagno
- VetAgro Sup, APCSe, Université de Lyon, Marcy l’Etoile, France
| | - John Colyer
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Philip Hopkins
- Leeds Institute of Medical Research at St James’s, University of Leeds, Leeds, United Kingdom
| | - Andrew Weightman
- School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester, United Kingdom
| | - Koichi Himori
- Graduate School of Health Sciences, Sapporo Medical University, Chuo-ku, Sapporo, Japan
| | - Takashi Yamada
- Graduate School of Health Sciences, Sapporo Medical University, Chuo-ku, Sapporo, Japan
| | - Joseph Bruton
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Derek Steele
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Håkan Westerblad
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Sarah Calaghan
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
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18
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Wei-LaPierre L, Ainbinder A, Tylock KM, Dirksen RT. Substrate-dependent and cyclophilin D-independent regulation of mitochondrial flashes in skeletal and cardiac muscle. Arch Biochem Biophys 2019; 665:122-131. [PMID: 30872061 PMCID: PMC6499064 DOI: 10.1016/j.abb.2019.03.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 03/05/2019] [Accepted: 03/06/2019] [Indexed: 01/20/2023]
Abstract
Mitochondrial flashes (mitoflashes) are stochastic events in the mitochondrial matrix detected by mitochondrial-targeted cpYFP (mt-cpYFP). Mitoflashes are quantal bursts of reactive oxygen species (ROS) production accompanied by modest matrix alkalinization and depolarization of the mitochondrial membrane potential. Mitoflashes are fundamental events present in a wide range of cell types. To date, the precise mechanisms for mitoflash generation and termination remain elusive. Transient opening of the mitochondrial membrane permeability transition pore (mPTP) during a mitoflash is proposed to account for the mitochondrial membrane potential depolarization. Here, we set out to compare the tissue-specific effects of cyclophilin D (CypD)-deficiency and mitochondrial substrates on mitoflash activity in skeletal and cardiac muscle. In contrast to previous reports, we found that CypD knockout did not alter the mitoflash frequency or other mitoflash properties in acutely isolated cardiac myocytes, skeletal muscle fibers, or isolated mitochondria from skeletal muscle and the heart. However, in skeletal muscle fibers, CypD deficiency resulted in a parallel increase in both activity-dependent mitochondrial Ca2+ uptake and activity-dependent mitoflash activity. Increases in both mitochondrial Ca2+ uptake and mitoflash activity following electrical stimulation were abolished by inhibition of mitochondrial Ca2+ uptake. We also found that mitoflash frequency and amplitude differ greatly between intact skeletal muscle fibers and cardiac myocytes, but that this difference is absent in isolated mitochondria. We propose that this difference may be due, in part, to differences in substrate availability in intact skeletal muscle fibers (primarily glycolytic) and cardiac myocytes (largely oxidative). Overall, we find that CypD does not contribute significantly in mitoflash biogenesis under basal conditions in skeletal and cardiac muscle, but does regulate mitoflash events during muscle activity. In addition, tissue-dependent differences in mitoflash frequency are strongly regulated by mitochondrial substrate availability.
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Affiliation(s)
- Lan Wei-LaPierre
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, 14642, USA.
| | - Alina Ainbinder
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Kevin M Tylock
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Robert T Dirksen
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, 14642, USA
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19
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Suman M, Sharpe JA, Bentham RB, Kotiadis VN, Menegollo M, Pignataro V, Molgó J, Muntoni F, Duchen MR, Pegoraro E, Szabadkai G. Inositol trisphosphate receptor-mediated Ca2+ signalling stimulates mitochondrial function and gene expression in core myopathy patients. Hum Mol Genet 2019; 27:2367-2382. [PMID: 29701772 PMCID: PMC6005141 DOI: 10.1093/hmg/ddy149] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 04/16/2018] [Indexed: 12/19/2022] Open
Abstract
Core myopathies are a group of childhood muscle disorders caused by mutations of the ryanodine receptor (RyR1), the Ca2+ release channel of the sarcoplasmic reticulum. These mutations have previously been associated with elevated inositol trisphosphate receptor (IP3R) levels in skeletal muscle myotubes derived from patients. However, the functional relevance and the relationship of IP3R mediated Ca2+ signalling with the pathophysiology of the disease is unclear. It has also been suggested that mitochondrial dysfunction underlies the development of central and diffuse multi-mini-cores, devoid of mitochondrial activity, which is a key pathological consequence of RyR1 mutations. Here we used muscle biopsies of central core and multi-minicore disease patients with RyR1 mutations, as well as cellular and in vivo mouse models of the disease to characterize global cellular and mitochondrial Ca2+ signalling, mitochondrial function and gene expression associated with the disease. We show that RyR1 mutations that lead to the depletion of the channel are associated with increased IP3-mediated nuclear and mitochondrial Ca2+ signals and increased mitochondrial activity. Moreover, western blot and microarray analysis indicated enhanced mitochondrial biogenesis at the transcriptional and protein levels and was reflected in increased mitochondrial DNA content. The phenotype was recapitulated by RYR1 silencing in mouse cellular myotube models. Altogether, these data indicate that remodelling of skeletal muscle Ca2+ signalling following loss of functional RyR1 mediates bioenergetic adaptation.
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Affiliation(s)
- Matteo Suman
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy.,Neuromuscular Unit, Department of Neuroscience, University of Padova, 35131 Padua, Italy
| | - Jenny A Sharpe
- Department of Cell and Developmental Biology, Consortium for Mitochondrial Research, University College London, London WC1E 6BT, UK
| | - Robert B Bentham
- Department of Cell and Developmental Biology, Consortium for Mitochondrial Research, University College London, London WC1E 6BT, UK.,The Francis Crick Institute, London NW1 1AT, UK
| | - Vassilios N Kotiadis
- Department of Cell and Developmental Biology, Consortium for Mitochondrial Research, University College London, London WC1E 6BT, UK
| | - Michela Menegollo
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Viviana Pignataro
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Jordi Molgó
- Commissariat à l'Energie Atomique et aux Énergies Alternatives (CEA), Institut des Sciences du Vivant Frédéric Joliot, Université Paris-Saclay, Service d'Ingénierie Moléculaire des Protéines, Gif-sur-Yvette 91191, France.,Institut des Neurosciences Paris-Saclay, UMR 9197, Centre National de la Recherche Scientifique (CNRS)/Université Paris-Sud, Gif-sur-Yvette 91198, France
| | - Francesco Muntoni
- University College London, Great Ormond Street Institute of Child Health Dubowitz Neuromuscular Centre and Medical Research Council (MRC) Centre for Neuromuscular Diseases, London WC1N 1EH, UK
| | - Michael R Duchen
- Department of Cell and Developmental Biology, Consortium for Mitochondrial Research, University College London, London WC1E 6BT, UK
| | - Elena Pegoraro
- Neuromuscular Unit, Department of Neuroscience, University of Padova, 35131 Padua, Italy
| | - Gyorgy Szabadkai
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy.,Department of Cell and Developmental Biology, Consortium for Mitochondrial Research, University College London, London WC1E 6BT, UK.,The Francis Crick Institute, London NW1 1AT, UK
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20
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Ex Vivo Measurements of Ca 2+ Transients in Intracellular Compartments of Skeletal Muscle Fibers by Means of Genetically Encoded Probes. Methods Mol Biol 2019; 1925:103-109. [PMID: 30674020 DOI: 10.1007/978-1-4939-9018-4_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We report a method for ex vivo measurements of Ca2+ transients in skeletal muscle fibers, both in the sarcoplasma and into the mitochondria. These measurements are based on the use of genetically encoded probes. Addition of targeting DNA sequences, in frame with the probe encoding sequence, ensures protein expression in specific compartments. The use of probes with different excitation spectra allows the simultaneous determination of cytosolic and mitochondrial Ca2+ transients in the same fiber. Probe encoding plasmids are expressed in flexor digitorum brevis (FDB) muscles by means of the in vivo electroporation technique. Measurements are then performed ex vivo in isolated single myofibers.
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21
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Pietrangelo L, Michelucci A, Ambrogini P, Sartini S, Guarnier FA, Fusella A, Zamparo I, Mammucari C, Protasi F, Boncompagni S. Muscle activity prevents the uncoupling of mitochondria from Ca 2+ Release Units induced by ageing and disuse. Arch Biochem Biophys 2018; 663:22-33. [PMID: 30578752 DOI: 10.1016/j.abb.2018.12.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 11/28/2018] [Accepted: 12/12/2018] [Indexed: 12/15/2022]
Abstract
In fast-twitch fibers from adult mice Ca2+ release units (CRUs, i.e. intracellular junctions of excitation-contraction coupling), and mitochondria are structurally linked to each other by small strands, named tethers. We recently showed that aging causes separation of a fraction of mitochondria from CRUs and a consequent impairment of the Ca2+ signaling between the two organelles. However, whether the uncoupling of mitochondria from CRUs is the result of aging per-se or the consequence of reduced muscle activity remains still unclear. Here we studied the association between mitochondria and CRUs: in a) extensor digitorum longus (EDL) muscles from 2 years old mice, either sedentary or trained for 1 year in wheel cages; and b) denervated EDL muscles from adult mice and rats. We analyzed muscle samples using a combination of structural (confocal and electron microscopy), biochemical (assessment of oxidative stress via western blot), and functional (ex-vivo contractile properties, and mitochondrial Ca2+ uptake) experimental procedures. The results collected in structural studies indicate that: a) ageing and denervation result in partial uncoupling between mitochondria and CRUs; b) exercise either maintains (in old mice) or restores (in transiently denervated rats) the association between the two organelles. Functional studies supported the hypothesis that CRU-mitochondria coupling is important for mitochondrial Ca2+ uptake, optimal force generation, and muscle performance. Taken together our results indicate that muscle activity maintains/improves proper association between CRUs and mitochondria.
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Affiliation(s)
- Laura Pietrangelo
- CeSI-Met - Center for Research on Ageing and Translational Medicine and DNICS - Dept. of Neuroscience, Imaging and Clinical Sciences, University G. d' Annunzio, I-66100, Italy.
| | - Antonio Michelucci
- CeSI-Met - Center for Research on Ageing and Translational Medicine and DNICS - Dept. of Neuroscience, Imaging and Clinical Sciences, University G. d' Annunzio, I-66100, Italy; Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, 14642, USA.
| | - Patrizia Ambrogini
- Dept. of Biomolecular Sciences, University of Urbino Carlo Bo, I-61029, Italy.
| | - Stefano Sartini
- Dept. of Biomolecular Sciences, University of Urbino Carlo Bo, I-61029, Italy.
| | - Flavia A Guarnier
- CeSI-Met - Center for Research on Ageing and Translational Medicine and DNICS - Dept. of Neuroscience, Imaging and Clinical Sciences, University G. d' Annunzio, I-66100, Italy.
| | - Aurora Fusella
- CeSI-Met - Center for Research on Ageing and Translational Medicine and DNICS - Dept. of Neuroscience, Imaging and Clinical Sciences, University G. d' Annunzio, I-66100, Italy.
| | - Ilaria Zamparo
- Dept. of Biomedical Sciences, University of Padova, I-35131, Italy.
| | | | - Feliciano Protasi
- CeSI-Met - Center for Research on Ageing and Translational Medicine and DMSI - Dept. of Medicine and Aging Sciences, University G. d'Annunzio of Chieti, I-66100, Italy.
| | - Simona Boncompagni
- CeSI-Met - Center for Research on Ageing and Translational Medicine and DNICS - Dept. of Neuroscience, Imaging and Clinical Sciences, University G. d' Annunzio, I-66100, Italy.
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22
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Cheng AJ, Place N, Westerblad H. Molecular Basis for Exercise-Induced Fatigue: The Importance of Strictly Controlled Cellular Ca 2+ Handling. Cold Spring Harb Perspect Med 2018; 8:cshperspect.a029710. [PMID: 28432118 DOI: 10.1101/cshperspect.a029710] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The contractile function of skeletal muscle declines during intense or prolonged physical exercise, that is, fatigue develops. Skeletal muscle fibers fatigue acutely during highly intense exercise when they have to rely on anaerobic metabolism. Early stages of fatigue involve impaired myofibrillar function, whereas decreased Ca2+ release from the sarcoplasmic reticulum (SR) becomes more important in later stages. SR Ca2+ release can also become reduced with more prolonged, lower intensity exercise, and it is then related to glycogen depletion. Increased reactive oxygen/nitrogen species can cause long-lasting impairments in SR Ca2+ release resulting in a prolonged force depression after exercise. In this article, we discuss molecular and cellular mechanisms of the above fatigue-induced changes, with special focus on multiple mechanisms to decrease SR Ca2+ release to avoid energy depletion and preserve muscle fiber integrity. We also discuss fatigue-related effects of exercise-induced Ca2+ fluxes over the sarcolemma and between the cytoplasm and mitochondria.
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Affiliation(s)
- Arthur J Cheng
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Nicolas Place
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Håkan Westerblad
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
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23
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Zhou J, Zhang J, Lu Y, Huang S, Xiao R, Zeng X, Zhang X, Li J, Wang T, Li T, Zhu L, Hu Q. Mitochondrial transplantation attenuates hypoxic pulmonary vasoconstriction. Oncotarget 2017; 7:31284-98. [PMID: 27121314 PMCID: PMC5058756 DOI: 10.18632/oncotarget.8893] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 04/02/2016] [Indexed: 01/15/2023] Open
Abstract
Hypoxia triggers pulmonary vasoconstriction, however induces relaxation of systemic arteries such as femoral arteries. Mitochondria are functionally and structurally heterogeneous between different cell types. The aim of this study was to reveal whether mitochondrial heterogeneity controls the distinct responses of pulmonary versus systemic artery smooth muscle cells to hypoxia. Intact mitochondria were transplanted into Sprague-Dawley rat pulmonary artery smooth muscle cells in culture and pulmonary arteries in vitro. Mitochondria retained functional after transplantation. The cross transplantation of mitochondria between pulmonary and femoral artery smooth muscle cells reversed acute hypoxia-induced alterations in cell membrane potential, [Ca2+]i signaling in smooth muscle cells and constriction or relaxation of arteries. Furthermore, the high or low amount of reactive oxygen species generation from mitochondria and their divergent (dis-)abilities in activating extracellular Ca2+-sensing receptor in smooth muscle cells were found to cause cell membrane potential depolarization, [Ca2+]i elevation and constriction of pulmonary arteries versus cell membrane potential hyperpolarization, [Ca2+]i decline and relaxation of femoral arteries in response to hypoxia, respectively. Our findings suggest that mitochondria necessarily determine the behaviors of vascular smooth muscle cells in response to hypoxia.
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Affiliation(s)
- Juan Zhou
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Key Laboratory of Pulmonary Diseases of Ministry of Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Current address: Department of Clinical Laboratory of Xuzhou Central Hospital, Xuzhou 221009, China
| | - Jiwei Zhang
- Department of Pathology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yankai Lu
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Key Laboratory of Pulmonary Diseases of Ministry of Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Department of Pathology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Songling Huang
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Key Laboratory of Pulmonary Diseases of Ministry of Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Rui Xiao
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Key Laboratory of Pulmonary Diseases of Ministry of Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Xianqin Zeng
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Key Laboratory of Pulmonary Diseases of Ministry of Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Xiuyun Zhang
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Key Laboratory of Pulmonary Diseases of Ministry of Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Jiansha Li
- Key Laboratory of Pulmonary Diseases of Ministry of Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Department of Pathology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Tao Wang
- Key Laboratory of Pulmonary Diseases of Ministry of Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Department of Respiratory and Critical Care Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Tongfei Li
- Department of Pathology, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan 442000, China
| | - Liping Zhu
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Key Laboratory of Pulmonary Diseases of Ministry of Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Qinghua Hu
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Key Laboratory of Pulmonary Diseases of Ministry of Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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24
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Zampieri S, Mammucari C, Romanello V, Barberi L, Pietrangelo L, Fusella A, Mosole S, Gherardi G, Höfer C, Löfler S, Sarabon N, Cvecka J, Krenn M, Carraro U, Kern H, Protasi F, Musarò A, Sandri M, Rizzuto R. Physical exercise in aging human skeletal muscle increases mitochondrial calcium uniporter expression levels and affects mitochondria dynamics. Physiol Rep 2017; 4:4/24/e13005. [PMID: 28039397 PMCID: PMC5210373 DOI: 10.14814/phy2.13005] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 09/26/2016] [Accepted: 09/26/2016] [Indexed: 01/04/2023] Open
Abstract
Age‐related sarcopenia is characterized by a progressive loss of muscle mass with decline in specific force, having dramatic consequences on mobility and quality of life in seniors. The etiology of sarcopenia is multifactorial and underlying mechanisms are currently not fully elucidated. Physical exercise is known to have beneficial effects on muscle trophism and force production. Alterations of mitochondrial Ca2+ homeostasis regulated by mitochondrial calcium uniporter (MCU) have been recently shown to affect muscle trophism in vivo in mice. To understand the relevance of MCU‐dependent mitochondrial Ca2+ uptake in aging and to investigate the effect of physical exercise on MCU expression and mitochondria dynamics, we analyzed skeletal muscle biopsies from 70‐year‐old subjects 9 weeks trained with either neuromuscular electrical stimulation (ES) or leg press. Here, we demonstrate that improved muscle function and structure induced by both trainings are linked to increased protein levels of MCU. Ultrastructural analyses by electron microscopy showed remodeling of mitochondrial apparatus in ES‐trained muscles that is consistent with an adaptation to physical exercise, a response likely mediated by an increased expression of mitochondrial fusion protein OPA1. Altogether these results indicate that the ES‐dependent physiological effects on skeletal muscle size and force are associated with changes in mitochondrial‐related proteins involved in Ca2+ homeostasis and mitochondrial shape. These original findings in aging human skeletal muscle confirm the data obtained in mice and propose MCU and mitochondria‐related proteins as potential pharmacological targets to counteract age‐related muscle loss.
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Affiliation(s)
- Sandra Zampieri
- Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria .,Venetian Institute of Molecular Medicine, Padova, Italy.,Department of Biomedical Science, University of Padova, Padova, Italy
| | | | | | - Laura Barberi
- DAHFMO-Unit of Histology and Medical Embryology, IIM, Institute Pasteur Cenci-Bolognetti, Sapienza University of Rome, Rome, Italy
| | - Laura Pietrangelo
- Department of Neuroscience, Imaging and Clinical Sciences, CeSI-Met - Center for Research on Aging and Translational Medicine & DNICS University G. d'Annunzio, Chieti, Italy
| | - Aurora Fusella
- Department of Neuroscience, Imaging and Clinical Sciences, CeSI-Met - Center for Research on Aging and Translational Medicine & DNICS University G. d'Annunzio, Chieti, Italy
| | - Simone Mosole
- Department of Biomedical Science, University of Padova, Padova, Italy
| | - Gaia Gherardi
- Department of Biomedical Science, University of Padova, Padova, Italy
| | - Christian Höfer
- Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria
| | - Stefan Löfler
- Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria
| | - Nejc Sarabon
- Science and Research Centre, Institute for Kinesiology Research, University of Primorska, Koper, Slovenia
| | - Jan Cvecka
- Faculty of Physical Education and Sport, Comenius University, Bratislava, Slovakia
| | - Matthias Krenn
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Ugo Carraro
- Institute of Electrodynamics, Microwave and Circuit Engineering, Vienna University of Technology, Vienna, Austria.,IRCCS Fondazione Ospedale San Camillo, Venezia, Italy
| | - Helmut Kern
- Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria
| | - Feliciano Protasi
- Department of Neuroscience, Imaging and Clinical Sciences, CeSI-Met - Center for Research on Aging and Translational Medicine & DNICS University G. d'Annunzio, Chieti, Italy
| | - Antonio Musarò
- DAHFMO-Unit of Histology and Medical Embryology, IIM, Institute Pasteur Cenci-Bolognetti, Sapienza University of Rome, Rome, Italy.,Center for Life Nano Science at Sapienza, Istituto Italiano di Tecnologia, Rome, Italy
| | - Marco Sandri
- Venetian Institute of Molecular Medicine, Padova, Italy.,Department of Biomedical Science, University of Padova, Padova, Italy
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25
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Antioxidant Treatment Reduces Formation of Structural Cores and Improves Muscle Function in RYR1 Y522S/WT Mice. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:6792694. [PMID: 29062463 PMCID: PMC5610828 DOI: 10.1155/2017/6792694] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 06/13/2017] [Indexed: 12/27/2022]
Abstract
Central core disease (CCD) is a congenital myopathy linked to mutations in the ryanodine receptor type 1 (RYR1), the sarcoplasmic reticulum Ca2+ release channel of skeletal muscle. CCD is characterized by formation of amorphous cores within muscle fibers, lacking mitochondrial activity. In skeletal muscle of RYR1Y522S/WT knock-in mice, carrying a human mutation in RYR1 linked to malignant hyperthermia (MH) with cores, oxidative stress is elevated and fibers present severe mitochondrial damage and cores. We treated RYR1Y522S/WT mice with N-acetylcysteine (NAC), an antioxidant provided ad libitum in drinking water for either 2 or 6 months. Our results show that 2 months of NAC treatment starting at 2 months of age, when mitochondrial and fiber damage was still minimal, (i) reduce formation of unstructured and contracture cores, (ii) improve muscle function, and (iii) decrease mitochondrial damage. The beneficial effect of NAC treatment is also evident following 6 months of treatment starting at 4 months of age, when structural damage was at an advanced stage. NAC exerts its protective effect likely by lowering oxidative stress, as supported by the reduction of 3-NT and SOD2 levels. This work suggests that NAC administration is beneficial to prevent mitochondrial damage and formation of cores and improve muscle function in RYR1Y522S/WT mice.
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26
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Periasamy M, Maurya SK, Sahoo SK, Singh S, Reis FCG, Bal NC. Role of SERCA Pump in Muscle Thermogenesis and Metabolism. Compr Physiol 2017. [DOI: 10.1002/cphy.c160030] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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27
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Pauly M, Angebault-Prouteau C, Dridi H, Notarnicola C, Scheuermann V, Lacampagne A, Matecki S, Fauconnier J. ER stress disturbs SR/ER-mitochondria Ca 2+ transfer: Implications in Duchenne muscular dystrophy. Biochim Biophys Acta Mol Basis Dis 2017. [PMID: 28625916 DOI: 10.1016/j.bbadis.2017.06.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Besides its role in calcium (Ca2+) homeostasis, the sarco-endoplamic reticulum (SR/ER) controls protein folding and is tethered to mitochondria. Under pathophysiological conditions the unfolded protein response (UPR) is associated with disturbance in SR/ER-mitochondria crosstalk. Here, we investigated whether ER stress altered SR/ER-mitochondria links, Ca2+ handling and muscle damage in WT (Wild Type) and mdx mice, the murine model of Duchenne Muscular Dystrophy (DMD). In WT mice, the SR/ER-mitochondria links were decreased in isolated FDB muscle fibers after injection of ER stress activator tunicamycin (TM). Ca2+ imaging revealed an increase of cytosolic Ca2+ transient and a decrease of mitochondrial Ca2+ uptake. The force generating capacity of muscle dropped after TM. This impaired contractile function was accompanied by an increase in autophagy markers and calpain-1 activation. Conversely, ER stress inhibitors restored SR/ER-mitochondria links, mitochondrial Ca2+ uptake and improved diaphragm contractility in mdx mice. Our findings demonstrated that ER stress-altered SR/ER-mitochondria links, disturbed Ca2+ handling and muscle function in WT and mdx mice. Thus, ER stress may open up a prospect of new therapeutic targets in DMD.
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Affiliation(s)
- Marion Pauly
- Inserm U1055, Hypoxie et Physiopathologies, Université Grenoble Alpes, Grenoble, France; Inserm U1046, UMR CNRS 9214, Université Montpellier, CHRU Montpellier, Montpellier, France
| | | | - Haikel Dridi
- Inserm U1046, UMR CNRS 9214, Université Montpellier, CHRU Montpellier, Montpellier, France
| | - Cécile Notarnicola
- Inserm U1046, UMR CNRS 9214, Université Montpellier, CHRU Montpellier, Montpellier, France
| | - Valérie Scheuermann
- Inserm U1046, UMR CNRS 9214, Université Montpellier, CHRU Montpellier, Montpellier, France
| | - Alain Lacampagne
- Inserm U1046, UMR CNRS 9214, Université Montpellier, CHRU Montpellier, Montpellier, France
| | - Stefan Matecki
- Inserm U1046, UMR CNRS 9214, Université Montpellier, CHRU Montpellier, Montpellier, France
| | - Jérémy Fauconnier
- Inserm U1046, UMR CNRS 9214, Université Montpellier, CHRU Montpellier, Montpellier, France.
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28
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Eshima H, Miura S, Senoo N, Hatakeyama K, Poole DC, Kano Y. Improved skeletal muscle Ca 2+ regulation in vivo following contractions in mice overexpressing PGC-1α. Am J Physiol Regul Integr Comp Physiol 2017; 312:R1017-R1028. [PMID: 28438761 DOI: 10.1152/ajpregu.00032.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/04/2017] [Accepted: 04/12/2017] [Indexed: 01/13/2023]
Abstract
In skeletal muscle, resting intracellular Ca2+ concentration ([Ca2+]i) homeostasis is exquisitely regulated by Ca2+ transport across the sarcolemmal, mitochondrial, and sarcoplasmic reticulum (SR) membranes. Of these three systems, the relative importance of the mitochondria in [Ca2+]i regulation remains poorly understood in in vivo skeletal muscle. We tested the hypothesis that the capacity for Ca2+ uptake by mitochondria is a primary factor in determining [Ca2+]i regulation in muscle at rest and following contractions. Tibialis anterior muscle of anesthetized peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α)-overexpressing (OE, increased mitochondria model) and wild-type (WT) littermate mice was exteriorized in vivo and loaded with the fluorescent probe fura 2-AM, and Rhod 2-AM Ca2+ buffering and mitochondrial [Ca2+] were evaluated at rest and during recovery from fatiguing tetanic contractions induced by electrical stimulation (120 s, 100 Hz). In addition, the effects of pharmacological inhibition of SR (thapsigargin) and mitochondrial [carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone (FCCP)] function were examined at rest. [Ca2+]i in WT remained elevated for the entire postcontraction recovery period (+6 ± 1% at 450 s), but in PGC-1α OE [Ca2+]i returned to resting baseline within 150 s. Thapsigargin immediately and substantially increased resting [Ca2+]i in WT, whereas in PGC-1α OE this effect was delayed and markedly diminished (WT, +12 ± 3; PGC-1α OE, +1 ± 2% at 600 s after thapsigargin treatment, P < 0.05). FCCP abolished this improvement of [Ca2+]i regulation in PGC-1α OE. Mitochondrial [Ca2+] accumulation was observed in PGC-1α OE following contractions and thapsigargin treatment. In the SR, PGC-1α OE downregulated SR Ca2+-ATPase 1 (Ca2+ uptake) and parvalbumin (Ca2+ buffering) protein levels, whereas mitochondrial Ca2+ uptake-related proteins (Mfn1, Mfn2, and mitochondrial Ca2+ uniporter) were upregulated. These data demonstrate a heretofore unappreciated role for skeletal muscle mitochondria in [Ca2+]i regulation in vivo following fatiguing tetanic contractions and at rest.
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Affiliation(s)
- Hiroaki Eshima
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Tokyo, Japan
| | - Shinji Miura
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan; and
| | - Nanami Senoo
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan; and
| | - Koji Hatakeyama
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Tokyo, Japan
| | - David C Poole
- Departments of Anatomy and Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Yutaka Kano
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Tokyo, Japan;
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29
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A chemical chaperone improves muscle function in mice with a RyR1 mutation. Nat Commun 2017; 8:14659. [PMID: 28337975 PMCID: PMC5376670 DOI: 10.1038/ncomms14659] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 01/20/2017] [Indexed: 12/28/2022] Open
Abstract
Mutations in the RYR1 gene cause severe myopathies. Mice with an I4895T mutation in the type 1 ryanodine receptor/Ca2+ release channel (RyR1) display muscle weakness and atrophy, but the underlying mechanisms are unclear. Here we show that the I4895T mutation in RyR1 decreases the amplitude of the sarcoplasmic reticulum (SR) Ca2+ transient, resting cytosolic Ca2+ levels, muscle triadin content and calsequestrin (CSQ) localization to the junctional SR, and increases endoplasmic reticulum (ER) stress/unfolded protein response (UPR) and mitochondrial ROS production. Treatment of mice carrying the I4895T mutation with a chemical chaperone, sodium 4-phenylbutyrate (4PBA), reduces ER stress/UPR and improves muscle function, but does not restore SR Ca2+ transients in I4895T fibres to wild type levels, suggesting that decreased SR Ca2+ release is not the major driver of the myopathy. These findings suggest that 4PBA, an FDA-approved drug, has potential as a therapeutic intervention for RyR1 myopathies that are associated with ER stress. Mutations in the RyR1 channel cause core myopathies. Here the authors show that ER stress and the unfolded protein response underlie the pathology caused by a common RyR1 channel mutation, and show that treatment with a chemical chaperone restores muscle function in mice.
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30
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Increased mitochondrial nanotunneling activity, induced by calcium imbalance, affects intermitochondrial matrix exchanges. Proc Natl Acad Sci U S A 2017; 114:E849-E858. [PMID: 28096415 DOI: 10.1073/pnas.1617788113] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Exchanges of matrix contents are essential to the maintenance of mitochondria. Cardiac mitochondrial exchange matrix content in two ways: by direct contact with neighboring mitochondria and over longer distances. The latter mode is supported by thin tubular protrusions, called nanotunnels, that contact other mitochondria at relatively long distances. Here, we report that cardiac myocytes of heterozygous mice carrying a catecholaminergic polymorphic ventricular tachycardia-linked RyR2 mutation (A4860G) show a unique and unusual mitochondrial response: a significantly increased frequency of nanotunnel extensions. The mutation induces Ca2+ imbalance by depressing RyR2 channel activity during excitation-contraction coupling, resulting in random bursts of Ca2+ release probably due to Ca2+ overload in the sarcoplasmic reticulum. We took advantage of the increased nanotunnel frequency in RyR2A4860G+/- cardiomyocytes to investigate and accurately define the ultrastructure of these mitochondrial extensions and to reconstruct the overall 3D distribution of nanotunnels using electron tomography. Additionally, to define the effects of communication via nanotunnels, we evaluated the intermitochondrial exchanges of matrix-targeted soluble fluorescent proteins, mtDsRed and photoactivable mtPA-GFP, in isolated cardiomyocytes by confocal microscopy. A direct comparison between exchanges occurring at short and long distances directly demonstrates that communication via nanotunnels is slower.
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31
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Li R, Steyn FJ, Stout MB, Lee K, Cully TR, Calderón JC, Ngo ST. Development of a high-throughput method for real-time assessment of cellular metabolism in intact long skeletal muscle fibre bundles. J Physiol 2016; 594:7197-7213. [PMID: 27619319 DOI: 10.1113/jp272988] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 09/07/2016] [Indexed: 12/28/2022] Open
Abstract
KEY POINTS We developed a method that allows for real-time assessment of cellular metabolism in isolated, intact long skeletal muscle fibre bundles from adult mice. This method can be used to study changes in mitochondrial function and fuel utilisation in live skeletal muscle fibre bundles. Our method enables flexibility in experimental design and high-throughput assessment of mitochondrial parameters in isolated skeletal muscle fibre bundles. Extensor digitorum longus (EDL) fibre bundles obtained from chronic high-fat diet fed mice had lower basal oxygen consumption under FCCP-induced maximal respiration, when compared to control chow-fed mice. EDL fibre bundles obtained from chronic high-fat diet fed mice had enhanced mitochondrial oxidation capacity under FCCP-induced maximal respiration, when compared to control chow-fed mice. ABSTRACT Metabolic dysfunction in skeletal muscle contributes to the aetiology and development of muscle diseases and metabolic diseases. As such, assessment of skeletal muscle cellular bioenergetics provides a powerful means to understand the role of skeletal muscle metabolism in disease and to identify possible therapeutic targets. Here, we developed a method that allows for the real-time assessment of cellular respiration in intact skeletal muscle fibre bundles obtained from the extensor digitorum longus (EDL) muscle of adult mice. Using this method, we assessed the contribution of ATP turnover and proton leak to basal mitochondrial oxygen consumption rate (OCR). Our data demonstrate that the mitochondria in EDL fibres are loosely coupled. Moreover, in the presence of carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP), we show that palmitate exposure induced comparable peak OCR and higher total OCR in EDL fibre bundles when compared to pyruvate exposure, suggesting that fatty acids might be a more sustainable fuel source for skeletal muscle when mitochondria are driven to maximal respiration. Application of this method to EDL fibre bundles obtained from chronic high-fat diet fed mice revealed lower basal OCR and enhanced mitochondrial oxidation capacity in the presence of FCCP when compared to the chow-diet fed control mice. By using a 96-well microplate format, our method provides a flexible and efficient platform to investigate mitochondrial parameters of intact skeletal muscle fibres obtained from adult mice.
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Affiliation(s)
- Rui Li
- School of Biomedical Sciences, University of Queensland, Brisbane, Australia
| | - Frederik J Steyn
- School of Biomedical Sciences, University of Queensland, Brisbane, Australia.,University of Queensland Centre for Clinical Research, Brisbane, Australia
| | - Michael B Stout
- Robert and Arlene Kogod Center on Aging, Mayo Clinic, Rochester, MN, USA
| | - Kevin Lee
- School of Biomedical Sciences, University of Queensland, Brisbane, Australia
| | - Tanya R Cully
- School of Biomedical Sciences, University of Queensland, Brisbane, Australia
| | - Juan C Calderón
- Department of Physiology and Biochemistry, Physiology and Biochemistry Research Group-PHYSIS, Faculty of Medicine, University of Antioquia, Medellín, Colombia
| | - Shyuan T Ngo
- School of Biomedical Sciences, University of Queensland, Brisbane, Australia.,University of Queensland Centre for Clinical Research, Brisbane, Australia.,Queensland Brain Institute, University of Queensland, Brisbane, Australia.,Department of Neurology, Royal Brisbane and Women's Hospital, Brisbane, Australia
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Pietrangelo L, D'Incecco A, Ainbinder A, Michelucci A, Kern H, Dirksen RT, Boncompagni S, Protasi F. Age-dependent uncoupling of mitochondria from Ca2⁺ release units in skeletal muscle. Oncotarget 2016; 6:35358-71. [PMID: 26485763 PMCID: PMC4742110 DOI: 10.18632/oncotarget.6139] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 09/22/2015] [Indexed: 12/03/2022] Open
Abstract
Calcium release units (CRUs) and mitochondria control myoplasmic [Ca2+] levels and ATP production in muscle, respectively. We recently reported that these two organelles are structurally connected by tethers, which promote proximity and proper Ca2+ signaling. Here we show that disposition, ultrastructure, and density of CRUs and mitochondria and their reciprocal association are compromised in muscle from aged mice. Specifically, the density of CRUs and mitochondria is decreased in muscle fibers from aged (>24 months) vs. adult (3-12 months), with an increased percentage of mitochondria being damaged and misplaced from their normal triadic position. A significant reduction in tether (13.8±0.4 vs. 5.5±0.3 tethers/100μm2) and CRU-mitochondrial pair density (37.4±0.8 vs. 27.0±0.7 pairs/100μm2) was also observed in aged mice. In addition, myoplasmic Ca2+ transient (1.68±0.08 vs 1.37±0.03) and mitochondrial Ca2+ uptake (9.6±0.050 vs 6.58±0.54) during repetitive high frequency tetanic stimulation were significantly decreased. Finally oxidative stress, assessed from levels of 3-nitrotyrosine (3-NT), Cu/Zn superoxide-dismutase (SOD1) and Mn superoxide dismutase (SOD2) expression, were significantly increased in aged mice. The reduced association between CRUs and mitochondria with aging may contribute to impaired cross-talk between the two organelles, possibly resulting in reduced efficiency in activity-dependent ATP production and, thus, to age-dependent decline of skeletal muscle performance.
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Affiliation(s)
- Laura Pietrangelo
- CeSI - Center for Research on Aging & DNICS, Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio, Chieti, Italy
| | - Alessandra D'Incecco
- CeSI - Center for Research on Aging & DNICS, Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio, Chieti, Italy
| | - Alina Ainbinder
- Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Antonio Michelucci
- CeSI - Center for Research on Aging & DNICS, Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio, Chieti, Italy
| | - Helmut Kern
- Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation & Institute of Physical Medicine and Rehabilitation, Wilhelminenspital, Vienna, Austria
| | - Robert T Dirksen
- Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Simona Boncompagni
- CeSI - Center for Research on Aging & DNICS, Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio, Chieti, Italy
| | - Feliciano Protasi
- CeSI - Center for Research on Aging & DNICS, Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio, Chieti, Italy
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Putman CT, Gallo M, Martins KJB, MacLean IM, Jendral MJ, Gordon T, Syrotuik DG, Dixon WT. Creatine loading elevates the intracellular phosphorylation potential and alters adaptive responses of rat fast-twitch muscle to chronic low-frequency stimulation. Appl Physiol Nutr Metab 2015; 40:671-82. [PMID: 26039543 DOI: 10.1139/apnm-2014-0300] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study tested the hypothesis that elevating the intracellular phosphorylation potential (IPP = [ATP]/[ADP]free) within rat fast-twitch tibialis anterior muscles by creatine (Cr) loading would prevent fast-to-slow fibre transitions induced by chronic low-frequency electrical stimulation (CLFS, 10 Hz, 12 h/day). Creatine-control and creatine-CLFS groups drank a solution of 1% Cr + 5% dextrose, ad libitum, for 10 days before and during 10 days of CLFS; dextrose-control and dextrose-CLFS groups drank 5% dextrose. Cr loading increased total Cr (P < 0.025), phosphocreatine (PCr) (P < 0.003), and the IPP (P < 0.0008) by 34%, 45%, and 64%, respectively. PCr and IPP were 46% (P < 0.002) and 76% (P < 0.02) greater in creatine-CLFS than in dextrose-CLFS. Higher IPP was confirmed by a 58% reduction in phospho-AMP-activated protein kinase α (Thr172) (P < 0.006). In dextrose-CLFS, myosin heavy chain (MyHC) I and IIa transcripts increased 32- and 38-fold (P < 0.006), respectively, whereas MyHC-IIb mRNA decreased by 75% (P < 0.03); the corresponding MyHC-I and MyHC-IIa protein contents increased by 2.0- (P < 0.03) and 2.7-fold (P < 0.05), respectively, and MyHC-IIb decreased by 30% (P < 0.03). In contrast, within creatine-CLFS, MyHC-I and MyHC-IIa mRNA were unchanged and MyHC-IIb mRNA decreased by 75% (P < 0.003); the corresponding MyHC isoform contents were not altered. Oxidative reference enzymes were similarly elevated (P < 0.01) in dextrose-CLFS and creatine-CLFS, but reciprocal reductions in glycolytic reference enzymes occurred only in dextrose-CLFS (P < 0.02). Preservation of the glycolytic potential and greater SERCA2 and parvalbumin contents in creatine-CLFS coincided with prolonged time to peak tension and half-rise time (P < 0.01). These results highlight the IPP as an important physiological regulator of muscle fibre plasticity and demonstrate that training-induced changes typically associated with improvements in muscular endurance or increased power output are not mutually exclusive in Cr-loaded muscles.
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Affiliation(s)
- Charles T Putman
- a Exercise Biochemistry Laboratory, Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB T6G 2H9, Canada.,b The Centre for Neuroscience, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - Maria Gallo
- a Exercise Biochemistry Laboratory, Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB T6G 2H9, Canada
| | - Karen J B Martins
- a Exercise Biochemistry Laboratory, Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB T6G 2H9, Canada
| | - Ian M MacLean
- a Exercise Biochemistry Laboratory, Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB T6G 2H9, Canada
| | - Michelle J Jendral
- a Exercise Biochemistry Laboratory, Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB T6G 2H9, Canada
| | - Tessa Gordon
- b The Centre for Neuroscience, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2E1, Canada.,d Division of Physical Medicine and Rehabilitation, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T5G 0B7, Canada
| | - Daniel G Syrotuik
- a Exercise Biochemistry Laboratory, Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB T6G 2H9, Canada
| | - Walter T Dixon
- c Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada
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Role of Mitofusin-2 in mitochondrial localization and calcium uptake in skeletal muscle. Cell Calcium 2014; 57:14-24. [PMID: 25477138 DOI: 10.1016/j.ceca.2014.11.002] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 11/04/2014] [Indexed: 12/21/2022]
Abstract
As muscle contraction requires ATP and Ca(2+), skeletal muscle function is highly dependent on communication between two major intracellular organelles: mitochondria and sarcoplasmic reticulum (SR). In adult skeletal muscle, mitochondria located within the I-band of the sarcomere are connected to the SR by small ∼10 nm electron dense tethers that bridge the outer mitochondrial membrane to the region of SR that is ∼130 nm from the site of Ca(2+) release. However, the molecular composition of tethers and their precise impact on mitochondrial Ca(2+) uptake in skeletal muscle is unclear. Mitofusin-2 (Mfn2) is a transmembrane GTPase present in both mitochondria and ER/SR membranes that forms trans-dimers and participates in mitochondrial fusion. Here we evaluated the role Mfn2 plays in mitochondrial morphology, localization, and functional SR-mitochondrial Ca(2+) crosstalk in adult skeletal muscle. Compared to a non-targeting (CTRL) siRNA, in vivo electroporation of 400 nM Mfn2 siRNA (Mfn2 KD) into mouse footpads resulted in a marked acute reduction (67±3%) in Mfn2 protein levels in flexor digitorum brevis (FDB) muscles that occurred without a change in other key Ca(2+) regulatory proteins. Electron microscopy analyses revealed that Mfn2 knockdown resulted in a change in mitochondria morphology and mis-localization of some mitochondria from the I-band to the A-band region of the sarcomere. To assess the role of Mfn2 in SR-mitochondrial crosstalk, we measured mitochondrial Ca(2+) uptake and myoplasmic Ca(2+) transients with rhod-2 and mag-fluo-4, respectively, during repetitive high frequency tetanic stimulation (5×100 Hz tetani, 500 ms/tetani, 0.2 duty cycle) in CTRL and Mfn2 KD fibers. Mitochondrial Ca(2+) uptake during repetitive tetanic stimulation was significantly reduced (40%) in Mfn2 KD FDB fibers, which was accompanied by a parallel elevation in the global electrically evoked myoplasmic Ca(2+) transient. Mfn2 KD also resulted in a reduction of the mitochondrial membrane potential, which contributed to the observed decrease in activity-dependent mitochondrial Ca(2+) uptake. Consistent with this idea, a similar decrease in mitochondrial Ca(2+) uptake was also observed in wild type fibers following a comparable reduction in mitochondrial membrane potential induced by acute exposure to a low concentration (50 nM) of carbonylcyanide-p-trifluoromethoxyphenylhydrazone (FCCP). In addition, both global and mitochondrial Ca(2+) transients during repetitive tetanic stimulation were similarly reduced by both slow (EGTA) and fast (BAPTA) Ca(2+) chelating agents. Together, these results indicate that Mfn2 promotes proper mitochondrial morphology, localization, and membrane potential required for optimal activity-dependent mitochondrial Ca(2+) uptake and buffering of the global myoplasmic Ca(2+) transient in adult skeletal muscle.
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In vivo calcium regulation in diabetic skeletal muscle. Cell Calcium 2014; 56:381-9. [PMID: 25224503 DOI: 10.1016/j.ceca.2014.08.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2014] [Revised: 07/23/2014] [Accepted: 08/09/2014] [Indexed: 01/30/2023]
Abstract
In skeletal muscle, dysfunctional contractile activity has been linked to impaired intracellular Ca(2+) concentration ([Ca(2+)]i) regulation. Muscle force production is impaired and fatigability and muscle fragility deteriorate with diabetes. Use of a novel in vivo model permits investigation of [Ca(2+)]i homeostasis in diabetic skeletal muscle. Within this in vivo environment we have shown that diabetes perturbs the Ca(2+) regulatory system such that resting [Ca(2+)]i homeostasis following muscle contractions is compromised and elevations of [Ca(2+)]i are exacerbated. This review considers the impact of diabetes on the capacity of skeletal muscle to regulate [Ca(2+)]i, following muscle contractions and, in particular, the relationship between muscle fatigue and elevated [Ca(2+)]i in a highly ecologically relevant circulation-intact environment. Importantly, the role of mitochondria in calcium sequestration and the possibility that diabetes impacts this process is explored. Given the profound microcirculatory dysfunction in diabetes this preparation offers the unique opportunity to study the interrelationships among microvascular function, blood-myocyte oxygen flux and [Ca(2+)]i as they relate to enhanced muscle fatigability and exercise intolerance.
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Orai1-dependent calcium entry promotes skeletal muscle growth and limits fatigue. Nat Commun 2014; 4:2805. [PMID: 24241282 PMCID: PMC3868675 DOI: 10.1038/ncomms3805] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 10/22/2013] [Indexed: 11/20/2022] Open
Abstract
Store-operated Ca2+ entry (SOCE) in skeletal muscle involves signaling between stromal interaction molecule 1 (STIM1) in the sarcoplasmic reticulum and Ca2+ selective Orai1 channels in the sarcolemma. Here we generate transgenic mice with muscle-specific expression of dominant-negative Orai1 (dnOrai1) and demonstrate that Orai1-dependent SOCE promotes growth and limits fatigue in adult skeletal muscle. dnOrai1 mice lack SOCE specifically in muscle but are fertile and thrive well into adulthood. Although muscle ultrastructure, excitation-contraction coupling fiber type, and expression of other Ca2+ regulatory proteins are unaltered, dnOrai1 mice exhibit reduced body weight, muscle mass, and fiber cross-sectional area. Importantly, during intense repetitive activity, dnOrai1 mice display increased susceptibility to fatigue at the single fibre, excised muscle, and whole animal levels. We further show that STIM1 and Orai1 proteins colocalise within the triad junction but do not exist in a preassembled context. These results show that Orai1-dependent SOCE has an important physiological role in muscles of adult mice.
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37
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Eisner V, Lenaers G, Hajnóczky G. Mitochondrial fusion is frequent in skeletal muscle and supports excitation-contraction coupling. ACTA ACUST UNITED AC 2014; 205:179-95. [PMID: 24751540 PMCID: PMC4003250 DOI: 10.1083/jcb.201312066] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Mitochondrial fusion is frequent in skeletal muscle, and its disruption jeopardizes excitation–contraction coupling and may contribute to the pathology of myopathies. Genetic targeting experiments indicate a fundamental role for mitochondrial fusion proteins in mammalian physiology. However, owing to the multiple functions of fusion proteins, their related phenotypes are not necessarily caused by altered mitochondrial fusion. Perhaps the biggest mystery is presented by skeletal muscle, where mostly globular-shaped mitochondria are densely packed into the narrow intermyofilamental space, limiting the interorganellar interactions. We show here that mitochondria form local networks and regularly undergo fusion events to share matrix content in skeletal muscle fibers. However, fusion events are less frequent and more stable in the fibers than in nondifferentiated myoblasts. Complementation among muscle mitochondria was suppressed by both in vivo genetic perturbations and chronic alcohol consumption that cause myopathy. An Mfn1-dependent pathway is revealed whereby fusion inhibition weakens the metabolic reserve of mitochondria to cause dysregulation of calcium oscillations during prolonged stimulation. Thus, fusion dynamically connects skeletal muscle mitochondria and its prolonged loss jeopardizes bioenergetics and excitation–contraction coupling, providing a potential pathomechanism contributing to myopathies.
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Affiliation(s)
- Verónica Eisner
- MitoCare Center, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107
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38
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Calderón JC, Bolaños P, Caputo C. The excitation-contraction coupling mechanism in skeletal muscle. Biophys Rev 2014; 6:133-160. [PMID: 28509964 PMCID: PMC5425715 DOI: 10.1007/s12551-013-0135-x] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 12/06/2013] [Indexed: 12/27/2022] Open
Abstract
First coined by Alexander Sandow in 1952, the term excitation-contraction coupling (ECC) describes the rapid communication between electrical events occurring in the plasma membrane of skeletal muscle fibres and Ca2+ release from the SR, which leads to contraction. The sequence of events in twitch skeletal muscle involves: (1) initiation and propagation of an action potential along the plasma membrane, (2) spread of the potential throughout the transverse tubule system (T-tubule system), (3) dihydropyridine receptors (DHPR)-mediated detection of changes in membrane potential, (4) allosteric interaction between DHPR and sarcoplasmic reticulum (SR) ryanodine receptors (RyR), (5) release of Ca2+ from the SR and transient increase of Ca2+ concentration in the myoplasm, (6) activation of the myoplasmic Ca2+ buffering system and the contractile apparatus, followed by (7) Ca2+ disappearance from the myoplasm mediated mainly by its reuptake by the SR through the SR Ca2+ adenosine triphosphatase (SERCA), and under several conditions movement to the mitochondria and extrusion by the Na+/Ca2+ exchanger (NCX). In this text, we review the basics of ECC in skeletal muscle and the techniques used to study it. Moreover, we highlight some recent advances and point out gaps in knowledge on particular issues related to ECC such as (1) DHPR-RyR molecular interaction, (2) differences regarding fibre types, (3) its alteration during muscle fatigue, (4) the role of mitochondria and store-operated Ca2+ entry in the general ECC sequence, (5) contractile potentiators, and (6) Ca2+ sparks.
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Affiliation(s)
- Juan C Calderón
- Physiology and Biochemistry Research Group-Physis, Department of Physiology and Biochemistry, Faculty of Medicine, University of Antioquia UdeA, Calle 70 No 52-21, Medellín, Colombia.
- Laboratory of Cellular Physiology, Centre of Biophysics and Biochemistry, Venezuelan Institute for Scientific Research (IVIC), Caracas, Venezuela.
- Departamento de Fisiología y Bioquímica, Grupo de Investigación en Fisiología y Bioquímica-Physis, Facultad de Medicina, Universidad de Antioquia, Calle 70 No 52-21, Medellín, Colombia.
| | - Pura Bolaños
- Laboratory of Cellular Physiology, Centre of Biophysics and Biochemistry, Venezuelan Institute for Scientific Research (IVIC), Caracas, Venezuela
| | - Carlo Caputo
- Laboratory of Cellular Physiology, Centre of Biophysics and Biochemistry, Venezuelan Institute for Scientific Research (IVIC), Caracas, Venezuela
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Zampieri S, Pietrangelo L, Loefler S, Fruhmann H, Vogelauer M, Burggraf S, Pond A, Grim-Stieger M, Cvecka J, Sedliak M, Tirpáková V, Mayr W, Sarabon N, Rossini K, Barberi L, De Rossi M, Romanello V, Boncompagni S, Musarò A, Sandri M, Protasi F, Carraro U, Kern H. Lifelong physical exercise delays age-associated skeletal muscle decline. J Gerontol A Biol Sci Med Sci 2014; 70:163-73. [PMID: 24550352 DOI: 10.1093/gerona/glu006] [Citation(s) in RCA: 187] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Aging is usually accompanied by a significant reduction in muscle mass and force. To determine the relative contribution of inactivity and aging per se to this decay, we compared muscle function and structure in (a) male participants belonging to a group of well-trained seniors (average of 70 years) who exercised regularly in their previous 30 years and (b) age-matched healthy sedentary seniors with (c) active young men (average of 27 years). The results collected show that relative to their sedentary cohorts, muscle from senior sportsmen have: (a) greater maximal isometric force and function, (b) better preserved fiber morphology and ultrastructure of intracellular organelles involved in Ca(2+) handling and ATP production, (c) preserved muscle fibers size resulting from fiber rescue by reinnervation, and (d) lowered expression of genes related to autophagy and reactive oxygen species detoxification. All together, our results indicate that: (a) skeletal muscle of senior sportsmen is actually more similar to that of adults than to that of age-matched sedentaries and (b) signaling pathways controlling muscle mass and metabolism are differently modulated in senior sportsmen to guarantee maintenance of skeletal muscle structure, function, bioenergetic characteristics, and phenotype. Thus, regular physical activity is a good strategy to attenuate age-related general decay of muscle structure and function (ClinicalTrials.gov: NCT01679977).
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Affiliation(s)
- S Zampieri
- Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria. Department of Biomedical Sciences, University of Padova, Italy.
| | - L Pietrangelo
- CeSI - Center for Research on Aging - Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio of Chieti, Italy
| | - S Loefler
- Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria
| | - H Fruhmann
- Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria
| | - M Vogelauer
- Department of Physical Medicine and Rehabilitation, Wilhelminenspital, Vienna, Austria
| | - S Burggraf
- Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria
| | - A Pond
- Anatomy Department, Southern Illinois University School of Medicine, Carbondale
| | - M Grim-Stieger
- Department of Physical Medicine and Rehabilitation, Wilhelminenspital, Vienna, Austria
| | - J Cvecka
- Faculty of Physical Education and Sport, Comenius University, Bratislava, Slovakia
| | - M Sedliak
- Faculty of Physical Education and Sport, Comenius University, Bratislava, Slovakia
| | - V Tirpáková
- Faculty of Physical Education and Sport, Comenius University, Bratislava, Slovakia
| | - W Mayr
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria
| | - N Sarabon
- University of Primorska, Science and Research Centre, Institute for Kinesilogical Research, Koper, Slovenia
| | - K Rossini
- Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria. Department of Biomedical Sciences, University of Padova, Italy
| | - L Barberi
- Institute Pasteur Cenci-Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, IIM, Sapienza University of Rome, Rome, Italy
| | - M De Rossi
- Institute Pasteur Cenci-Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, IIM, Sapienza University of Rome, Rome, Italy
| | - V Romanello
- Department of Biomedical Sciences, University of Padova, Italy. Venetian Institute of Molecular Medicine, Dulbecco Telethon Institute, Padova, Italy
| | - S Boncompagni
- CeSI - Center for Research on Aging - Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio of Chieti, Italy
| | - A Musarò
- Institute Pasteur Cenci-Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, IIM, Sapienza University of Rome, Rome, Italy
| | - M Sandri
- Department of Biomedical Sciences, University of Padova, Italy. Venetian Institute of Molecular Medicine, Dulbecco Telethon Institute, Padova, Italy
| | - F Protasi
- CeSI - Center for Research on Aging - Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio of Chieti, Italy
| | - U Carraro
- Department of Biomedical Sciences, University of Padova, Italy
| | - H Kern
- Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria. Department of Physical Medicine and Rehabilitation, Wilhelminenspital, Vienna, Austria
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40
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Lamboley CR, Murphy RM, McKenna MJ, Lamb GD. Sarcoplasmic reticulum Ca2+ uptake and leak properties, and SERCA isoform expression, in type I and type II fibres of human skeletal muscle. J Physiol 2014; 592:1381-95. [PMID: 24469076 DOI: 10.1113/jphysiol.2013.269373] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The Ca(2+) uptake properties of the sarcoplasmic reticulum (SR) were compared between type I and type II fibres of vastus lateralis muscle of young healthy adults. Individual mechanically skinned muscle fibres were exposed to solutions with the free [Ca(2+)] heavily buffered in the pCa range (-log10[Ca(2+)]) 7.3-6.0 for set times and the amount of net SR Ca(2+) accumulation determined from the force response elicited upon emptying the SR of all Ca(2+). Western blotting was used to determine fibre type and the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) isoform present in every fibre examined. Type I fibres contained only SERCA2 and displayed half-maximal Ca(2+) uptake rate at ∼pCa 6.8, whereas type II fibres contained only SERCA1 and displayed half-maximal Ca(2+) uptake rate at ∼pCa 6.6. Maximal Ca(2+) uptake rate was ∼0.18 and ∼0.21 mmol Ca(2+) (l fibre)(-1) s(-1) in type I and type II fibres, respectively, in good accord with previously measured SR ATPase activity. Increasing free [Mg(2+)] from 1 to 3 mM had no significant effect on the net Ca(2+) uptake rate at pCa 6.0, indicating that there was little or no calcium-induced calcium release occurring through the Ca(2+) release channels during uptake in either fibre type. Ca(2+) leakage from the SR at pCa 8.5, which is thought to occur at least in part through the SERCA, was ∼2-fold lower in type II fibres than in type I fibres, and was little affected by the presence of ADP, in marked contrast to the larger SR Ca(2+) leak observed in rat muscle fibres under the same conditions. The higher affinity of Ca(2+) uptake in the type I human fibres can account for the higher relative level of SR Ca(2+) loading observed in type I compared to type II fibres, and the SR Ca(2+) leakage characteristics of the human fibres suggest that the SERCAs are regulated differently from those in rat and contribute comparatively less to resting metabolic rate.
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Affiliation(s)
- C R Lamboley
- Department of Zoology, La Trobe University, Melbourne, Victoria 3086, Australia.
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41
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Bolaños P, Guillen A, Gámez A, Caputo C. Quantifying SOCE fluorescence measurements in mammalian muscle fibres. The effects of ryanodine and osmotic shocks. J Muscle Res Cell Motil 2013; 34:379-93. [PMID: 24129906 DOI: 10.1007/s10974-013-9360-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 09/18/2013] [Indexed: 11/28/2022]
Abstract
We have quantified Ca(2+) entry through store operated calcium channels in mice muscle fibres, measuring the rates of change of myoplasmic [Ca(2+)], d[Ca(2+)](myo)/dt, and of Ca(2+) removal, d[Ca(2+)](Removal)/dt, turning store operated calcium entry (SOCE) ON, and OFF, by switching on or off external Ca(2+). In depleted fibres, poisoned with 10 μM cyclopiazonic acid SOCE influx was about 3 μM/s. Ryanodine (50 μM) caused a robust, nifedipine (50 μM) independent, increase in SOCE activation to 8.6 μM/s. Decreasing medium osmolarity from 300 to 220 mOsm/L, decreased SOCE to 0.9 μM/s, while increasing osmolarity from 220 to 400 mOsm/L potentiated SOCE to 43.6 μM/s. Ryanodine inhibited the effects of hypotonicity. Experiments using 2-aminoethoxydiphenyl borate, nifedipine, or Mn(2+) quenching, strongly suggest that the increased [Ca(2+)](myo) by ryanodine or hypertonic shock is mediated by potentiated SOCE activation. The Ca(2+) response decay, quantified by d[Ca(2+)](Removal)/dt, indicates a robust residual Ca(2+) removal mechanism in sarco-endoplasmic reticulum calcium ATPase poisoned fibres. SOCE high sensitivity to osmotic shocks, or to ryanodine receptor (RyR) binding, suggests its high dependency on the structural relationship between its molecular constituents, Orai1 and stromal interaction molecule and the sarcoplasmic reticulum and plasma membranes, in the triadic junctional region, where RyRs, are conspicuously present. This study demonstrates that SOCE machinery is highly sensitive to structural changes caused by binding of an agonist to its receptor or by imposed osmotical volume changes.
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Affiliation(s)
- Pura Bolaños
- Laboratorio de Fisiología Celular, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Venezuela,
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42
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Lamboley CR, Murphy RM, McKenna MJ, Lamb GD. Endogenous and maximal sarcoplasmic reticulum calcium content and calsequestrin expression in type I and type II human skeletal muscle fibres. J Physiol 2013; 591:6053-68. [PMID: 24127619 DOI: 10.1113/jphysiol.2013.265900] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The relationship between sarcoplasmic reticulum (SR) Ca(2+) content and calsequestrin (CSQ) isoforms was investigated in human skeletal muscle. A fibre-lysing assay was used to quantify the endogenous Ca(2+) content and maximal Ca(2+) capacity of the SR in skinned segments of type I and type II fibres from vastus lateralis muscles of young healthy adults. Western blotting of individual fibres showed the great majority contained either all fast or all slow isoforms of myosin heavy chain (MHC), troponins C and I, tropomyosin and SERCA, and that the strontium sensitivity of the force response was closely indicative of the troponin C isoform present. The endogenous SR Ca(2+) content was slightly lower in type I compared to type II fibres (0.76 ± 0.03 and 0.85 ± 0.02 mmol Ca(2+) per litre of fibre, respectively), with virtually all of this Ca(2+) evidently being in the SR, as it could be rapidly released with a caffeine-low [Mg(2+)] solution (only 0.08 ± 0.01 and <0.07 mmol l(-1), respectively, remaining). The maximal Ca(2+) content that could be reached with SR Ca(2+) loading was 1.45 ± 0.04 and 1.79 ± 0.03 mmol l(-1) in type I and type II fibres, respectively (P < 0.05). In non-lysed skinned fibres, where the SR remained functional, repeated cycles of caffeine-induced Ca(2+) release and subsequent Ca(2+) reloading similarly indicated that (i) maximal SR Ca(2+) content was lower in type I fibres than in type II fibres (P < 0.05), and (ii) the endogenous Ca(2+) content represented a greater percentage of maximal content in type I fibres compared to type II fibres (∼59% and 41%, respectively, P < 0.05). Type II fibres were found on average to contain ∼3-fold more CSQ1 and ∼5-fold less CSQ2 than type I fibres (P < 0.001). The findings are consistent with the SR Ca(2+) content characteristics in human type II fibres being primarily determined by the CSQ1 abundance, and in type I fibres by the combined amounts of both CSQ1 and CSQ2.
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Affiliation(s)
- C R Lamboley
- G. D. Lamb: Department of Zoology, La Trobe University, Melbourne, Victoria 3086, Australia.
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Scorzeto M, Giacomello M, Toniolo L, Canato M, Blaauw B, Paolini C, Protasi F, Reggiani C, Stienen GJM. Mitochondrial Ca2+-handling in fast skeletal muscle fibers from wild type and calsequestrin-null mice. PLoS One 2013; 8:e74919. [PMID: 24098358 PMCID: PMC3789688 DOI: 10.1371/journal.pone.0074919] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 08/07/2013] [Indexed: 11/19/2022] Open
Abstract
Mitochondrial calcium handling and its relation with calcium released from sarcoplasmic reticulum (SR) in muscle tissue are subject of lively debate. In this study we aimed to clarify how the SR determines mitochondrial calcium handling using dCASQ-null mice which lack both isoforms of the major Ca2+-binding protein inside SR, calsequestrin. Mitochondrial free Ca2+-concentration ([Ca2+]mito) was determined by means of a genetically targeted ratiometric FRET-based probe. Electron microscopy revealed a highly significant increase in intermyofibrillar mitochondria (+55%) and augmented coupling (+12%) between Ca2+ release units of the SR and mitochondria in dCASQ-null vs. WT fibers. Significant differences in the baseline [Ca2+]mito were observed between quiescent WT and dCASQ-null fibers, but not in the resting cytosolic Ca2+ concentration. The rise in [Ca2+]mito during electrical stimulation occurred in 20−30 ms, while the decline during and after stimulation was governed by 4 rate constants of approximately 40, 1.6, 0.2 and 0.03 s−1. Accordingly, frequency-dependent increase in [Ca2+]mito occurred during sustained contractions. In dCASQ-null fibers the increases in [Ca2+]mito were less pronounced than in WT fibers and even lower when extracellular calcium was removed. The amplitude and duration of [Ca2+]mito transients were increased by inhibition of mitochondrial Na+/Ca2+ exchanger (mNCX). These results provide direct evidence for fast Ca2+ accumulation inside the mitochondria, involvement of the mNCX in mitochondrial Ca2+-handling and a dependence of mitochondrial Ca2+-handling on intracellular (SR) and external Ca2+ stores in fast skeletal muscle fibers. dCASQ-null mice represent a model for malignant hyperthermia. The differences in structure and in mitochondrial function observed relative to WT may represent compensatory mechanisms for the disease-related reduction of calcium storage capacity of the SR and/or SR Ca2+-leakage.
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Affiliation(s)
- Michele Scorzeto
- Department of Biomedical Sciences and Interuniversity Institute of Myology (IIM), University of Padova, Padua, Italy
| | | | - Luana Toniolo
- Department of Biomedical Sciences and Interuniversity Institute of Myology (IIM), University of Padova, Padua, Italy
| | - Marta Canato
- Department of Biomedical Sciences and Interuniversity Institute of Myology (IIM), University of Padova, Padua, Italy
| | - Bert Blaauw
- Department of Biomedical Sciences and Interuniversity Institute of Myology (IIM), University of Padova, Padua, Italy
- Venetian Institute of Molecular Medicine, Padua, Italy
| | - Cecilia Paolini
- Department of Neuroscience and Imaging (DNI) and Center for Research on Ageing (CeSI), and Interuniversity Institute of Myology (IIM), University G. d' Annunzio, Chieti, Italy
| | - Feliciano Protasi
- Department of Neuroscience and Imaging (DNI) and Center for Research on Ageing (CeSI), and Interuniversity Institute of Myology (IIM), University G. d' Annunzio, Chieti, Italy
| | - Carlo Reggiani
- Department of Biomedical Sciences and Interuniversity Institute of Myology (IIM), University of Padova, Padua, Italy
| | - Ger J. M. Stienen
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
- Department of Physics and Astronomy, VU University Amsterdam, Amsterdam, The Netherlands
- * E-mail:
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Abstract
Calcium (Ca(2+)) uptake into the mitochondrial matrix is critically important to cellular function. As a regulator of matrix Ca(2+) levels, this flux influences energy production and can initiate cell death. If large, this flux could potentially alter intracellular Ca(2+) ([Ca(2+)]i) signals. Despite years of study, fundamental disagreements on the extent and speed of mitochondrial Ca(2+) uptake still exist. Here, we review and quantitatively analyze mitochondrial Ca(2+) uptake fluxes from different tissues and interpret the results with respect to the recently proposed mitochondrial Ca(2+) uniporter (MCU) candidate. This quantitative analysis yields four clear results: (i) under physiological conditions, Ca(2+) influx into the mitochondria via the MCU is small relative to other cytosolic Ca(2+) extrusion pathways; (ii) single MCU conductance is ∼6-7 pS (105 mM [Ca(2+)]), and MCU flux appears to be modulated by [Ca(2+)]i, suggesting Ca(2+) regulation of MCU open probability (P(O)); (iii) in the heart, two features are clear: the number of MCU channels per mitochondrion can be calculated, and MCU probability is low under normal conditions; and (iv) in skeletal muscle and liver cells, uptake per mitochondrion varies in magnitude but total uptake per cell still appears to be modest. Based on our analysis of available quantitative data, we conclude that although Ca(2+) critically regulates mitochondrial function, the mitochondria do not act as a significant dynamic buffer of cytosolic Ca(2+) under physiological conditions. Nevertheless, with prolonged (superphysiological) elevations of [Ca(2+)]i, mitochondrial Ca(2+) uptake can increase 10- to 1,000-fold and begin to shape [Ca(2+)]i dynamics.
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Yi M, Weaver D, Eisner V, Várnai P, Hunyady L, Ma J, Csordás G, Hajnóczky G. Switch from ER-mitochondrial to SR-mitochondrial calcium coupling during muscle differentiation. Cell Calcium 2012; 52:355-65. [PMID: 22784666 DOI: 10.1016/j.ceca.2012.05.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 05/25/2012] [Accepted: 05/28/2012] [Indexed: 11/26/2022]
Abstract
Emerging evidence indicates that mitochondria are locally coupled to endoplasmic reticulum (ER) Ca2+ release in myoblasts and to sarcoplasmic reticulum (SR) Ca2+ release in differentiated muscle fibers in order to regulate cytoplasmic calcium dynamics and match metabolism with cell activity. However, the mechanism of the developmental transition from ER to SR coupling remains unclear. We have studied mitochondrial sensing of IP3 receptor (IP3R)- and ryanodine receptor (RyR)-mediated Ca2+ signals in H9c2 myoblasts and differentiating myotubes, as well as the attendant changes in mitochondrial morphology. Mitochondria in myoblasts were largely elongated, luminally connected and relatively few in number, whereas the myotubes were densely packed with globular mitochondria that displayed limited luminal continuity. Vasopressin, an IP3-linked agonist, evoked a large cytoplasmic Ca2+ ([Ca2+]c) increase in myoblasts, whereas it elicited a smaller response in myotubes. Conversely, RyR-mediated Ca2+ release induced by caffeine, was not observed in myoblasts, but triggered a large [Ca2+]c signal in myotubes. Both the IP3R and the RyR-mediated [Ca2+]c rise was closely associated with a mitochondrial matrix Ca2+ ([Ca2+]m) signal. Every myotube that showed a [Ca2+]c spike also displayed a [Ca2+]m response. Addition of IP3 to permeabilized myoblasts and caffeine to permeabilized myotubes also resulted in a rapid [Ca2+]m rise, indicating that Ca2+ was delivered via local coupling of the ER/SR and mitochondria. Thus, as RyRs are expressed during muscle differentiation, the local connection between RyR and mitochondrial Ca2+ uptake sites also appears. When RyR1 was exogenously introduced to myoblasts by overexpression, the [Ca2+]m signal appeared together with the [Ca2+]c signal, however the mitochondrial morphology remained unchanged. Thus, RyR expression alone is sufficient to induce the steps essential for their alignment with mitochondrial Ca2+ uptake sites, whereas the mitochondrial proliferation and reshaping utilize either downstream or alternative pathways.
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Affiliation(s)
- Muqing Yi
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Nunes PM, van de Weijer T, Veltien A, Arnts H, Hesselink MKC, Glatz JFC, Schrauwen P, Tack CJ, Heerschap A. Increased intramyocellular lipids but unaltered in vivo mitochondrial oxidative phosphorylation in skeletal muscle of adipose triglyceride lipase-deficient mice. Am J Physiol Endocrinol Metab 2012; 303:E71-81. [PMID: 22496349 DOI: 10.1152/ajpendo.00597.2011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Adipose triglyceride lipase (ATGL) is a lipolytic enzyme that is highly specific for triglyceride hydrolysis. The ATGL-knockout mouse (ATGL(-/-)) accumulates lipid droplets in various tissues, including skeletal muscle, and has poor maximal running velocity and endurance capacity. In this study, we tested whether abnormal lipid accumulation in skeletal muscle impairs mitochondrial oxidative phosphorylation, and hence, explains the poor muscle performance of ATGL(-/-) mice. In vivo ¹H magnetic resonance spectroscopy of the tibialis anterior of ATGL(-/-) mice revealed that its intramyocellular lipid pool is approximately sixfold higher than in WT controls (P = 0.0007). In skeletal muscle of ATGL(-/-) mice, glycogen content was decreased by 30% (P < 0.05). In vivo ³¹P magnetic resonance spectra of resting muscles showed that WT and ATGL(-/-) mice have a similar energy status: [PCr], [P(i)], PCr/ATP ratio, PCr/P(i) ratio, and intracellular pH. Electrostimulated muscles from WT and ATGL(-/-) mice showed the same PCr depletion and pH reduction. Moreover, the monoexponential fitting of the PCr recovery curve yielded similar PCr recovery times (τPCr; 54.1 ± 6.1 s for the ATGL(-/-) and 58.1 ± 5.8 s for the WT), which means that overall muscular mitochondrial oxidative capacity was comparable between the genotypes. Despite similar in vivo mitochondrial oxidative capacities, the electrostimulated muscles from ATGL(-/-) mice displayed significantly lower force production and increased muscle relaxation time than the WT. These findings suggest that mechanisms other than mitochondrial dysfunction cause the impaired muscle performance of ATGL(-/-) mice.
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Affiliation(s)
- P M Nunes
- Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
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Protasi F, Paolini C, Canato M, Reggiani C, Quarta M. Lessons from calsequestrin-1 ablation in vivo: much more than a Ca(2+) buffer after all. J Muscle Res Cell Motil 2011; 32:257-70. [PMID: 22130610 DOI: 10.1007/s10974-011-9277-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 11/09/2011] [Indexed: 10/15/2022]
Abstract
Calsequestrin type-1 (CASQ1), the main sarcoplasmic reticulum (SR) Ca(2+) binding protein, plays a dual role in skeletal fibers: a) it provides a large pool of rapidly-releasable Ca(2+) during excitation-contraction (EC) coupling; and b) it modulates the activity of ryanodine receptors (RYRs), the SR Ca(2+) release channels. We have generated a mouse lacking CASQ1 in order to further characterize the role of CASQ1 in skeletal muscle. Contrary to initial expectations, CASQ1 ablation is compatible with normal motor activity, in spite of moderate muscle atrophy. However, CASQ1 deficiency results in profound remodeling of the EC coupling apparatus: shrinkage of junctional SR lumen; proliferation of SR/transverse-tubule contacts; and increased density of RYRs. While force development during a twitch is preserved, it is nevertheless characterized by a prolonged time course, likely reflecting impaired Ca(2+) re-uptake by the SR. Finally, lack of CASQ1 also results in increased rate of SR Ca(2+) depletion and inability of muscle to sustain tension during a prolonged tetani. All modifications are more pronounced (or only found) in fast-twitch extensor digitorum longus muscle compared to slow-twitch soleus muscle, likely because the latter expresses higher amounts of calsequestrin type-2 (CASQ2). Surprisingly, male CASQ1-null mice also exhibit a marked increased rate of spontaneous mortality suggestive of a stress-induced phenotype. Consistent with this idea, CASQ1-null mice exhibit an increased susceptibility to undergo a hypermetabolic syndrome characterized by whole body contractures, rhabdomyolysis, hyperthermia and sudden death in response to halothane- and heat-exposure, a phenotype remarkably similar to human malignant hyperthermia and environmental heat-stroke. The latter findings validate the CASQ1 gene as a candidate for linkage analysis in human muscle disorders.
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Affiliation(s)
- Feliciano Protasi
- CeSI-Center for Research on Ageing & DNI-Department of Neuroscience and Imaging, University Gabriele d’Annunzioof Chieti, Via Colle dell’Ara, 66100 Chieti, Italy.
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