1
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Gao L, Ardiel E, Nurrish S, Kaplan JM. Voltage-induced calcium release in Caenorhabditis elegans body muscles. Proc Natl Acad Sci U S A 2024; 121:e2317753121. [PMID: 38687794 PMCID: PMC11087772 DOI: 10.1073/pnas.2317753121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 04/03/2024] [Indexed: 05/02/2024] Open
Abstract
Type 1 voltage-activated calcium channels (CaV1) in the plasma membrane trigger calcium release from the sarcoplasmic reticulum (SR) by two mechanisms. In voltage-induced calcium release (VICR), CaV1 voltage sensing domains are directly coupled to ryanodine receptors (RYRs), an SR calcium channel. In calcium-induced calcium release (CICR), calcium ions flowing through activated CaV1 channels bind and activate RYR channels. VICR is thought to occur exclusively in vertebrate skeletal muscle while CICR occurs in all other muscles (including all invertebrate muscles). Here, we use calcium-activated SLO-2 potassium channels to analyze CaV1-SR coupling in Caenorhabditis elegans body muscles. SLO-2 channels were activated by both VICR and external calcium. VICR-mediated SLO-2 activation requires two SR calcium channels (RYRs and IP3 Receptors), JPH-1/Junctophilin, a PDZ (PSD95, Dlg1, ZO-1 domain) binding domain (PBD) at EGL-19/CaV1's carboxy-terminus, and SHN-1/Shank (a scaffolding protein that binds EGL-19's PBD). Thus, VICR occurs in invertebrate muscles.
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Affiliation(s)
- Luna Gao
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA02114
- Department of Neurobiology, Harvard Medical School, Boston, MA02115
| | - Evan Ardiel
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA02114
- Department of Neurobiology, Harvard Medical School, Boston, MA02115
| | - Stephen Nurrish
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA02114
- Department of Neurobiology, Harvard Medical School, Boston, MA02115
| | - Joshua M. Kaplan
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA02114
- Department of Neurobiology, Harvard Medical School, Boston, MA02115
- Program in Neuroscience, Harvard Medical School, Boston, MA02115
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2
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Xu J, Liao C, Yin CC, Li G, Zhu Y, Sun F. In situ structural insights into the excitation-contraction coupling mechanism of skeletal muscle. SCIENCE ADVANCES 2024; 10:eadl1126. [PMID: 38507485 PMCID: PMC10954225 DOI: 10.1126/sciadv.adl1126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 02/12/2024] [Indexed: 03/22/2024]
Abstract
Excitation-contraction coupling (ECC) is a fundamental mechanism in control of skeletal muscle contraction and occurs at triad junctions, where dihydropyridine receptors (DHPRs) on transverse tubules sense excitation signals and then cause calcium release from the sarcoplasmic reticulum via coupling to type 1 ryanodine receptors (RyR1s), inducing the subsequent contraction of muscle filaments. However, the molecular mechanism remains unclear due to the lack of structural details. Here, we explored the architecture of triad junction by cryo-electron tomography, solved the in situ structure of RyR1 in complex with FKBP12 and calmodulin with the resolution of 16.7 Angstrom, and found the intact RyR1-DHPR supercomplex. RyR1s arrange into two rows on the terminal cisternae membrane by forming right-hand corner-to-corner contacts, and tetrads of DHPRs bind to RyR1s in an alternating manner, forming another two rows on the transverse tubule membrane. This unique arrangement is important for synergistic calcium release and provides direct evidence of physical coupling in ECC.
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Affiliation(s)
- Jiashu Xu
- Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chenyi Liao
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Chang-Cheng Yin
- Department of Biophysics, The Health Science Center, Peking University, Beijing 100191, China
- Electron Microscopy Analysis Laboratory, The Health Science Center, Peking University, Beijing 100191, China
- Center for Protein Science, Peking University, Beijing 100871, China
| | - Guohui Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Yun Zhu
- Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Fei Sun
- Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Center for Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, Guangdong, 510005, China
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3
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Hall DD, Takeshima H, Song LS. Structure, Function, and Regulation of the Junctophilin Family. Annu Rev Physiol 2024; 86:123-147. [PMID: 37931168 PMCID: PMC10922073 DOI: 10.1146/annurev-physiol-042022-014926] [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] [Indexed: 11/08/2023]
Abstract
In both excitable and nonexcitable cells, diverse physiological processes are linked to different calcium microdomains within nanoscale junctions that form between the plasma membrane and endo-sarcoplasmic reticula. It is now appreciated that the junctophilin protein family is responsible for establishing, maintaining, and modulating the structure and function of these junctions. We review foundational findings from more than two decades of research that have uncovered how junctophilin-organized ultrastructural domains regulate evolutionarily conserved biological processes. We discuss what is known about the junctophilin family of proteins. Our goal is to summarize the current knowledge of junctophilin domain structure, function, and regulation and to highlight emerging avenues of research that help our understanding of the transcriptional, translational, and post-translational regulation of this gene family and its roles in health and during disease.
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Affiliation(s)
- Duane D Hall
- Department of Internal Medicine, Division of Cardiovascular Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA; ,
| | - Hiroshi Takeshima
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Long-Sheng Song
- Department of Internal Medicine, Division of Cardiovascular Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA; ,
- Department of Biochemistry and Molecular Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
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4
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Dixon RE, Trimmer JS. Endoplasmic Reticulum-Plasma Membrane Junctions as Sites of Depolarization-Induced Ca 2+ Signaling in Excitable Cells. Annu Rev Physiol 2023; 85:217-243. [PMID: 36202100 PMCID: PMC9918718 DOI: 10.1146/annurev-physiol-032122-104610] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Membrane contact sites between endoplasmic reticulum (ER) and plasma membrane (PM), or ER-PM junctions, are found in all eukaryotic cells. In excitable cells they play unique roles in organizing diverse forms of Ca2+ signaling as triggered by membrane depolarization. ER-PM junctions underlie crucial physiological processes such as excitation-contraction coupling, smooth muscle contraction and relaxation, and various forms of activity-dependent signaling and plasticity in neurons. In many cases the structure and molecular composition of ER-PM junctions in excitable cells comprise important regulatory feedback loops linking depolarization-induced Ca2+ signaling at these sites to the regulation of membrane potential. Here, we describe recent findings on physiological roles and molecular composition of native ER-PM junctions in excitable cells. We focus on recent studies that provide new insights into canonical forms of depolarization-induced Ca2+ signaling occurring at junctional triads and dyads of striated muscle, as well as the diversity of ER-PM junctions in these cells and in smooth muscle and neurons.
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Affiliation(s)
- Rose E Dixon
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, California, USA;
| | - James S Trimmer
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, California, USA;
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5
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Del Rivero Morfin PJ, Marx SO, Ben-Johny M. Sympathetic Nervous System Regulation of Cardiac Calcium Channels. Handb Exp Pharmacol 2023. [PMID: 36592229 DOI: 10.1007/164_2022_632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Calcium influx through voltage-gated calcium channels, Cav1.2, in cardiomyocytes initiates excitation-contraction coupling in the heart. The force and rate of cardiac contraction are modulated by the sympathetic nervous system, mediated substantially by changes in intracellular calcium. Norepinephrine released from sympathetic neurons innervating the heart and epinephrine secreted by the adrenal chromaffin cells bind to β-adrenergic receptors on the sarcolemma of cardiomyocytes initiating a signaling cascade that generates cAMP and activates protein kinase A, the targets of which control calcium influx. For decades, the mechanisms by which PKA regulated calcium channels in the heart were not known. Recently, these mechanisms have been elucidated. In this chapter, we will review the history of the field and the studies that led to the identification of the evolutionarily conserved process.
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Affiliation(s)
- Pedro J Del Rivero Morfin
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Steven O Marx
- Division of Cardiology, Department of Medicine, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA. .,Department of Pharmacology and Molecular Signaling, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA.
| | - Manu Ben-Johny
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA.
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6
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Campiglio M, Dyrda A, Tuinte WE, Török E. Ca V1.1 Calcium Channel Signaling Complexes in Excitation-Contraction Coupling: Insights from Channelopathies. Handb Exp Pharmacol 2023; 279:3-39. [PMID: 36592225 DOI: 10.1007/164_2022_627] [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] [Indexed: 01/03/2023]
Abstract
In skeletal muscle, excitation-contraction (EC) coupling relies on the mechanical coupling between two ion channels: the L-type voltage-gated calcium channel (CaV1.1), located in the sarcolemma and functioning as the voltage sensor of EC coupling, and the ryanodine receptor 1 (RyR1), located on the sarcoplasmic reticulum serving as the calcium release channel. To this day, the molecular mechanism by which these two ion channels are linked remains elusive. However, recently, skeletal muscle EC coupling could be reconstituted in heterologous cells, revealing that only four proteins are essential for this process: CaV1.1, RyR1, and the cytosolic proteins CaVβ1a and STAC3. Due to the crucial role of these proteins in skeletal muscle EC coupling, any mutation that affects any one of these proteins can have devastating consequences, resulting in congenital myopathies and other pathologies.Here, we summarize the current knowledge concerning these four essential proteins and discuss the pathophysiology of the CaV1.1, RyR1, and STAC3-related skeletal muscle diseases with an emphasis on the molecular mechanisms. Being part of the same signalosome, mutations in different proteins often result in congenital myopathies with similar symptoms or even in the same disease.
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Affiliation(s)
- Marta Campiglio
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria.
| | - Agnieszka Dyrda
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Wietske E Tuinte
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Enikő Török
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
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7
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Chivet M, McCluskey M, Nicot AS, Brocard J, Beaufils M, Giovannini D, Giannesini B, Poreau B, Brocard J, Humbert S, Saudou F, Fauré J, Marty I. Huntingtin regulates calcium fluxes in skeletal muscle. J Gen Physiol 2022; 155:213700. [PMID: 36409218 PMCID: PMC9682417 DOI: 10.1085/jgp.202213103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 09/09/2022] [Accepted: 09/03/2022] [Indexed: 11/22/2022] Open
Abstract
The expression of the Huntingtin protein, well known for its involvement in the neurodegenerative Huntington's disease, has been confirmed in skeletal muscle. The impact of HTT deficiency was studied in human skeletal muscle cell lines and in a mouse model with inducible and muscle-specific HTT deletion. Characterization of calcium fluxes in the knock-out cell lines demonstrated a reduction in excitation-contraction (EC) coupling, related to an alteration in the coupling between the dihydropyridine receptor and the ryanodine receptor, and an increase in the amount of calcium stored within the sarcoplasmic reticulum, linked to the hyperactivity of store-operated calcium entry (SOCE). Immunoprecipitation experiments demonstrated an association of HTT with junctophilin 1 (JPH1) and stromal interaction molecule 1 (STIM1), both providing clues on the functional effects of HTT deletion on calcium fluxes. Characterization of muscle strength and muscle anatomy of the muscle-specific HTT-KO mice demonstrated that HTT deletion induced moderate muscle weakness and mild muscle atrophy associated with histological abnormalities, similar to the phenotype observed in tubular aggregate myopathy. Altogether, this study points toward the hypotheses of the involvement of HTT in EC coupling via its interaction with JPH1, and on SOCE via its interaction with JPH1 and/or STIM1.
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Affiliation(s)
- Mathilde Chivet
- CHU Grenoble Alpes, Grenoble Institut Neurosciences, INSERM, U1216, Université Grenoble Alpes, Grenoble, France
| | - Maximilian McCluskey
- CHU Grenoble Alpes, Grenoble Institut Neurosciences, INSERM, U1216, Université Grenoble Alpes, Grenoble, France
| | - Anne Sophie Nicot
- CHU Grenoble Alpes, Grenoble Institut Neurosciences, INSERM, U1216, Université Grenoble Alpes, Grenoble, France
| | - Julie Brocard
- CHU Grenoble Alpes, Grenoble Institut Neurosciences, INSERM, U1216, Université Grenoble Alpes, Grenoble, France
| | - Mathilde Beaufils
- CHU Grenoble Alpes, Grenoble Institut Neurosciences, INSERM, U1216, Université Grenoble Alpes, Grenoble, France
| | - Diane Giovannini
- CHU Grenoble Alpes, Grenoble Institut Neurosciences, INSERM, U1216, Université Grenoble Alpes, Grenoble, France
| | - Benoit Giannesini
- Centre National de la Recherche Scientifique, Centre de Résonance Magnétique Biologique et Médicale, Aix Marseille University, Marseille, France
| | - Brice Poreau
- CHU Grenoble Alpes, Grenoble Institut Neurosciences, INSERM, U1216, Université Grenoble Alpes, Grenoble, France
| | - Jacques Brocard
- CHU Grenoble Alpes, Grenoble Institut Neurosciences, INSERM, U1216, Université Grenoble Alpes, Grenoble, France
| | - Sandrine Humbert
- CHU Grenoble Alpes, Grenoble Institut Neurosciences, INSERM, U1216, Université Grenoble Alpes, Grenoble, France
| | - Frédéric Saudou
- CHU Grenoble Alpes, Grenoble Institut Neurosciences, INSERM, U1216, Université Grenoble Alpes, Grenoble, France
| | - Julien Fauré
- CHU Grenoble Alpes, Grenoble Institut Neurosciences, INSERM, U1216, Université Grenoble Alpes, Grenoble, France
| | - Isabelle Marty
- CHU Grenoble Alpes, Grenoble Institut Neurosciences, INSERM, U1216, Université Grenoble Alpes, Grenoble, France,Correspondence to Isabelle Marty:
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8
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Rossi D, Catallo MR, Pierantozzi E, Sorrentino V. Mutations in proteins involved in E-C coupling and SOCE and congenital myopathies. J Gen Physiol 2022; 154:213407. [PMID: 35980353 PMCID: PMC9391951 DOI: 10.1085/jgp.202213115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 07/15/2022] [Accepted: 07/21/2022] [Indexed: 11/24/2022] Open
Abstract
In skeletal muscle, Ca2+ necessary for muscle contraction is stored and released from the sarcoplasmic reticulum (SR), a specialized form of endoplasmic reticulum through the mechanism known as excitation–contraction (E-C) coupling. Following activation of skeletal muscle contraction by the E-C coupling mechanism, replenishment of intracellular stores requires reuptake of cytosolic Ca2+ into the SR by the activity of SR Ca2+-ATPases, but also Ca2+ entry from the extracellular space, through a mechanism called store-operated calcium entry (SOCE). The fine orchestration of these processes requires several proteins, including Ca2+ channels, Ca2+ sensors, and Ca2+ buffers, as well as the active involvement of mitochondria. Mutations in genes coding for proteins participating in E-C coupling and SOCE are causative of several myopathies characterized by a wide spectrum of clinical phenotypes, a variety of histological features, and alterations in intracellular Ca2+ balance. This review summarizes current knowledge on these myopathies and discusses available knowledge on the pathogenic mechanisms of disease.
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Affiliation(s)
- Daniela Rossi
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy.,Interdepartmental Program of Molecular Diagnosis and Pathogenetic Mechanisms of Rare Genetic Diseases, Azienda Ospedaliero Universitaria Senese, Siena, Italy
| | - Maria Rosaria Catallo
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Enrico Pierantozzi
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Vincenzo Sorrentino
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy.,Interdepartmental Program of Molecular Diagnosis and Pathogenetic Mechanisms of Rare Genetic Diseases, Azienda Ospedaliero Universitaria Senese, Siena, Italy
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9
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Perni S, Beam K. Junctophilins 1, 2, and 3 all support voltage-induced Ca2+ release despite considerable divergence. J Gen Physiol 2022; 154:212989. [PMID: 35089322 PMCID: PMC9488633 DOI: 10.1085/jgp.202113024] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 01/05/2022] [Indexed: 11/23/2022] Open
Abstract
In skeletal muscle, depolarization of the plasma membrane (PM) causes conformational changes of the calcium channel CaV1.1 that then activate RYR1 to release calcium from the SR. Being independent of extracellular calcium entry, this process is termed voltage-induced calcium release. In skeletal muscle, junctophilins (JPHs) 1 and 2 form the SR–PM junctions at which voltage-induced calcium release occurs. Previous work demonstrated that JPH2 is able to recapitulate voltage-induced calcium release when expressed in HEK293 cells together with CaV1.1, β1a, Stac3, and RYR1. However, it is unknown whether JPH1 and the more distantly related neuronal JPH3 and JPH4 might also function in this manner, a question of interest because different JPH isoforms diverge in their interactions with RYR1. Here, we show that, like JPH2, JPH1 and JPH3, coexpressed with CaV1.1, β1a, Stac3, and RYR1 in HEK293 cells, cause colocalization of CaV1.1 and RYR1 at ER–PM junctions. Furthermore, potassium depolarization elicited cytoplasmic calcium transients in cells in which WT CaV1.1 was replaced with the calcium impermeant mutant CaV1.1(N617D), indicating that JPH1, JPH2, and JPH3 can all support voltage-induced calcium release, despite sequence divergence and differences in interaction with RYR1. Conversely, JPH4-induced ER–PM junctions contain CaV1.1 but not RYR1, and cells expressing JPH4 are unable to produce depolarization-induced calcium transients. Thus, JPHs seem to act primarily to form ER–PM junctions and to recruit the necessary signaling proteins to these junctions but appear not to be directly involved in the functional interactions between these proteins.
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Affiliation(s)
- Stefano Perni
- Department of Physiology and Biophysics, University of Colorado, Anschutz Medical Campus, Aurora, CO
| | - Kurt Beam
- Department of Physiology and Biophysics, University of Colorado, Anschutz Medical Campus, Aurora, CO
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10
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Bolaños P, Calderón JC. Excitation-contraction coupling in mammalian skeletal muscle: Blending old and last-decade research. Front Physiol 2022; 13:989796. [PMID: 36117698 PMCID: PMC9478590 DOI: 10.3389/fphys.2022.989796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
The excitation–contraction coupling (ECC) in skeletal muscle refers to the Ca2+-mediated link between the membrane excitation and the mechanical contraction. The initiation and propagation of an action potential through the membranous system of the sarcolemma and the tubular network lead to the activation of the Ca2+-release units (CRU): tightly coupled dihydropyridine and ryanodine (RyR) receptors. The RyR gating allows a rapid, massive, and highly regulated release of Ca2+ from the sarcoplasmic reticulum (SR). The release from triadic places generates a sarcomeric gradient of Ca2+ concentrations ([Ca2+]) depending on the distance of a subcellular region from the CRU. Upon release, the diffusing Ca2+ has multiple fates: binds to troponin C thus activating the contractile machinery, binds to classical sarcoplasmic Ca2+ buffers such as parvalbumin, adenosine triphosphate and, experimentally, fluorescent dyes, enters the mitochondria and the SR, or is recycled through the Na+/Ca2+ exchanger and store-operated Ca2+ entry (SOCE) mechanisms. To commemorate the 7th decade after being coined, we comprehensively and critically reviewed “old”, historical landmarks and well-established concepts, and blended them with recent advances to have a complete, quantitative-focused landscape of the ECC. We discuss the: 1) elucidation of the CRU structures at near-atomic resolution and its implications for functional coupling; 2) reliable quantification of peak sarcoplasmic [Ca2+] using fast, low affinity Ca2+ dyes and the relative contributions of the Ca2+-binding mechanisms to the whole concert of Ca2+ fluxes inside the fibre; 3) articulation of this novel quantitative information with the unveiled structural details of the molecular machinery involved in mitochondrial Ca2+ handing to understand how and how much Ca2+ enters the mitochondria; 4) presence of the SOCE machinery and its different modes of activation, which awaits understanding of its magnitude and relevance in situ; 5) pharmacology of the ECC, and 6) emerging topics such as the use and potential applications of super-resolution and induced pluripotent stem cells (iPSC) in ECC. Blending the old with the new works better!
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Affiliation(s)
- Pura Bolaños
- Laboratory of Cellular Physiology, Centre of Biophysics and Biochemistry, Venezuelan Institute for Scientific Research (IVIC), Caracas, Venezuela
| | - Juan C. Calderón
- Physiology and Biochemistry Research Group-PHYSIS, Faculty of Medicine, University of Antioquia, Medellín, Colombia
- *Correspondence: Juan C. Calderón,
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11
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Ashida Y, Himori K, Tokuda N, Naito A, Yamauchi N, Takenaka-Ninagawa N, Aoki Y, Sakurai H, Yamada T. Dissociation of SH3 and cysteine rich domain 3 and junctophilin 1 from dihydropyridine receptor in dystrophin-deficient muscles. Am J Physiol Cell Physiol 2022; 323:C885-C895. [PMID: 35912995 DOI: 10.1152/ajpcell.00163.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The disruption of excitation-contraction (EC) coupling and subsequent reduction in Ca2+ release from the sarcoplasmic reticulum (SR) have been shown to account for muscle weakness seen in patients with Duchenne muscular dystrophy (DMD). Here, we examined the mechanisms underlying EC uncoupling in skeletal muscles from mdx52 and DMD-null/NSG mice, animal models for DMD, focusing on the SH3 and cysteine rich domain 3 (STAC3) and junctophilin 1 (JP1), which link the dihydropyridine receptor (DHPR) in the transverse tubule and the ryanodine receptor 1 in the SR. The isometric plantarflexion torque normalized to muscle weight of whole plantar flexor muscles was depressed in mdx52 and DMD-null/NSG mice compared to their control mice. This was accompanied by increased autolysis of calpain-1, decreased levels of STAC3 and JP1 content, and dissociation of STAC3 and JP1 from DHPR-α1s in gastrocnemius muscles. Moreover, in vitro mechanistic experiments demonstrated that STAC3 and JP1 underwent Ca2+-dependent proteolysis which was less pronounced in dystrophin-deficient muscles where calpastatin, the endogenous calpain inhibitor, was upregulated. Eccentric contractions further enhanced autolysis of calpain-1 and proteolysis of STAC3 and JP1 that were associated with severe torque depression in gastrocnemius muscles from DMD-null/NSG mice. These data suggest that Ca2+-dependent proteolysis of STAC3 and JP1 may be an essential factor causing muscle weakness due to EC coupling failure in dystrophin-deficient muscles.
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Affiliation(s)
- Yuki Ashida
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan.,Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
| | - Koichi Himori
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan.,Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
| | - Nao Tokuda
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
| | - Azuma Naito
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
| | - Nao Yamauchi
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
| | | | - Yoshitsugu Aoki
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Hidetoshi Sakurai
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Takashi Yamada
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
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12
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Zhou J, Liu H, Lin Y, Zhao J. Membrane Occupation and Recognition Nexus (MORN) motif controls protein localization and function. FEBS Lett 2022; 596:1839-1850. [PMID: 35568981 DOI: 10.1002/1873-3468.14378] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 04/23/2022] [Accepted: 05/07/2022] [Indexed: 11/06/2022]
Abstract
Membrane Occupation and Recognition Nexus (MORN) motif was first defined in 2000, when it was identified in the junctophilin protein family. Dozens of studies have been published ever since, mainly focusing on the function of a given MORN motif-containing protein in parasites, plants or animal cells. Proteins with MORN motifs are not only expressed in most animal and plant cell types but also significantly differ in their intracellular localization, suggesting that the MORN motifs may fulfil multiple physiological functions. Recent studies have found that MORN motif-containing proteins junctophilin 1/2 and MORN3 play a role in cardiac hypertrophy, skeletal muscle fiber stability and cancer. Hence, MORN motif-containing proteins may be exploited to develop improved treatments for various pathological conditions, such as cardiovascular diseases. Here, we review current research on MORN motif-containing proteins in different organisms and provide both ideas and approaches for follow-up exploration of their functions and applications.
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Affiliation(s)
- Jinrun Zhou
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Qingdao, 266237, P. R. China
| | - Honghong Liu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Qingdao, 266237, P. R. China
| | - Yushuang Lin
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Qingdao, 266237, P. R. China
| | - Jing Zhao
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Qingdao, 266237, P. R. China
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13
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A bridge from the endoplasmic reticulum to the plasma membrane comes into view. Proc Natl Acad Sci U S A 2022; 119:e2202254119. [PMID: 35353604 PMCID: PMC9169776 DOI: 10.1073/pnas.2202254119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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14
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Rossi D, Pierantozzi E, Amadsun DO, Buonocore S, Rubino EM, Sorrentino V. The Sarcoplasmic Reticulum of Skeletal Muscle Cells: A Labyrinth of Membrane Contact Sites. Biomolecules 2022; 12:488. [PMID: 35454077 PMCID: PMC9026860 DOI: 10.3390/biom12040488] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/14/2022] [Accepted: 03/18/2022] [Indexed: 12/17/2022] Open
Abstract
The sarcoplasmic reticulum of skeletal muscle cells is a highly ordered structure consisting of an intricate network of tubules and cisternae specialized for regulating Ca2+ homeostasis in the context of muscle contraction. The sarcoplasmic reticulum contains several proteins, some of which support Ca2+ storage and release, while others regulate the formation and maintenance of this highly convoluted organelle and mediate the interaction with other components of the muscle fiber. In this review, some of the main issues concerning the biology of the sarcoplasmic reticulum will be described and discussed; particular attention will be addressed to the structure and function of the two domains of the sarcoplasmic reticulum supporting the excitation-contraction coupling and Ca2+-uptake mechanisms.
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Affiliation(s)
- Daniela Rossi
- Department of Molecular and Developmental Medicine, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy; (E.P.); (D.O.A.); (S.B.); (E.M.R.); (V.S.)
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15
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Yang ZF, Panwar P, McFarlane CR, Tuinte WE, Campiglio M, Van Petegem F. Structures of the junctophilin/voltage-gated calcium channel interface reveal hot spot for cardiomyopathy mutations. Proc Natl Acad Sci U S A 2022; 119:e2120416119. [PMID: 35238659 PMCID: PMC8916002 DOI: 10.1073/pnas.2120416119] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 01/31/2022] [Indexed: 01/19/2023] Open
Abstract
SignificanceIon channels have evolved the ability to communicate with one another, either through protein-protein interactions, or indirectly via intermediate diffusible messenger molecules. In special cases, the channels are part of different membranes. In muscle tissue, the T-tubule membrane is in proximity to the sarcoplasmic reticulum, allowing communication between L-type calcium channels and ryanodine receptors. This process is critical for excitation-contraction coupling and requires auxiliary proteins like junctophilin (JPH). JPHs are targets for disease-associated mutations, most notably hypertrophic cardiomyopathy mutations in the JPH2 isoform. Here we provide high-resolution snapshots of JPH, both alone and in complex with a calcium channel peptide, and show how this interaction is targeted by cardiomyopathy mutations.
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Affiliation(s)
- Zheng Fang Yang
- Department of Biochemistry and Molecular Biology, The Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Pankaj Panwar
- Department of Biochemistry and Molecular Biology, The Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Ciaran R. McFarlane
- Department of Biochemistry and Molecular Biology, The Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Wietske E. Tuinte
- Institute of Physiology, Medical University of Innsbruck, Innsbruck, 6020 Austria
| | - Marta Campiglio
- Institute of Physiology, Medical University of Innsbruck, Innsbruck, 6020 Austria
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, The Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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16
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Copola AGL, Dos Santos ÍGD, Coutinho LL, Del-Bem LEV, de Almeida Campos-Junior PH, da Conceição IMCA, Nogueira JM, do Carmo Costa A, Silva GAB, Jorge EC. Transcriptomic characterization of the molecular mechanisms induced by RGMa during skeletal muscle nuclei accretion and hypertrophy. BMC Genomics 2022; 23:188. [PMID: 35255809 PMCID: PMC8902710 DOI: 10.1186/s12864-022-08396-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 02/15/2022] [Indexed: 12/02/2022] Open
Abstract
Background The repulsive guidance molecule a (RGMa) is a GPI-anchor axon guidance molecule first found to play important roles during neuronal development. RGMa expression patterns and signaling pathways via Neogenin and/or as BMP coreceptors indicated that this axon guidance molecule could also be working in other processes and diseases, including during myogenesis. Previous works from our research group have consistently shown that RGMa is expressed in skeletal muscle cells and that its overexpression induces both nuclei accretion and hypertrophy in muscle cell lineages. However, the cellular components and molecular mechanisms induced by RGMa during the differentiation of skeletal muscle cells are poorly understood. In this work, the global transcription expression profile of RGMa-treated C2C12 myoblasts during the differentiation stage, obtained by RNA-seq, were reported. Results RGMa treatment could modulate the expression pattern of 2,195 transcripts in C2C12 skeletal muscle, with 943 upregulated and 1,252 downregulated. Among them, RGMa interfered with the expression of several RNA types, including categories related to the regulation of RNA splicing and degradation. The data also suggested that nuclei accretion induced by RGMa could be due to their capacity to induce the expression of transcripts related to ‘adherens junsctions’ and ‘extracellular-cell adhesion’, while RGMa effects on muscle hypertrophy might be due to (i) the activation of the mTOR-Akt independent axis and (ii) the regulation of the expression of transcripts related to atrophy. Finally, RGMa induced the expression of transcripts that encode skeletal muscle structural proteins, especially from sarcolemma and also those associated with striated muscle cell differentiation. Conclusions These results provide comprehensive knowledge of skeletal muscle transcript changes and pathways in response to RGMa. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-022-08396-w.
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Affiliation(s)
- Aline Gonçalves Lio Copola
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av Antonio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais, 31.270-901, Brasil
| | - Íria Gabriela Dias Dos Santos
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av Antonio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais, 31.270-901, Brasil
| | - Luiz Lehmann Coutinho
- Departamento de Zootecnia, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, Brasil
| | - Luiz Eduardo Vieira Del-Bem
- Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil
| | | | | | - Júlia Meireles Nogueira
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av Antonio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais, 31.270-901, Brasil
| | - Alinne do Carmo Costa
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av Antonio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais, 31.270-901, Brasil
| | - Gerluza Aparecida Borges Silva
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av Antonio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais, 31.270-901, Brasil
| | - Erika Cristina Jorge
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av Antonio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais, 31.270-901, Brasil.
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17
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Nusier M, Shah AK, Dhalla NS. Structure-Function Relationships and Modifications of Cardiac Sarcoplasmic Reticulum Ca2+-Transport. Physiol Res 2022; 70:S443-S470. [DOI: 10.33549/physiolres.934805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Sarcoplasmic reticulum (SR) is a specialized tubular network, which not only maintains the intracellular concentration of Ca2+ at a low level but is also known to release and accumulate Ca2+ for the occurrence of cardiac contraction and relaxation, respectively. This subcellular organelle is composed of several phospholipids and different Ca2+-cycling, Ca2+-binding and regulatory proteins, which work in a coordinated manner to determine its function in cardiomyocytes. Some of the major proteins in the cardiac SR membrane include Ca2+-pump ATPase (SERCA2), Ca2+-release protein (ryanodine receptor), calsequestrin (Ca2+-binding protein) and phospholamban (regulatory protein). The phosphorylation of SR Ca2+-cycling proteins by protein kinase A or Ca2+-calmodulin kinase (directly or indirectly) has been demonstrated to augment SR Ca2+-release and Ca2+-uptake activities and promote cardiac contraction and relaxation functions. The activation of phospholipases and proteases as well as changes in different gene expressions under different pathological conditions have been shown to alter the SR composition and produce Ca2+-handling abnormalities in cardiomyocytes for the development of cardiac dysfunction. The post-translational modifications of SR Ca2+ cycling proteins by processes such as oxidation, nitrosylation, glycosylation, lipidation, acetylation, sumoylation, and O GlcNacylation have also been reported to affect the SR Ca2+ release and uptake activities as well as cardiac contractile activity. The SR function in the heart is also influenced in association with changes in cardiac performance by several hormones including thyroid hormones and adiponectin as well as by exercise-training. On the basis of such observations, it is suggested that both Ca2+-cycling and regulatory proteins in the SR membranes are intimately involved in determining the status of cardiac function and are thus excellent targets for drug development for the treatment of heart disease.
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Affiliation(s)
| | | | - NS Dhalla
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen, Research Centre, 351 Tache Avenue, Winnipeg, MB, R2H 2A6 Canada.
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18
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Dixon RE. Nanoscale Organization, Regulation, and Dynamic Reorganization of Cardiac Calcium Channels. Front Physiol 2022; 12:810408. [PMID: 35069264 PMCID: PMC8769284 DOI: 10.3389/fphys.2021.810408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Accepted: 11/30/2021] [Indexed: 12/19/2022] Open
Abstract
The architectural specializations and targeted delivery pathways of cardiomyocytes ensure that L-type Ca2+ channels (CaV1.2) are concentrated on the t-tubule sarcolemma within nanometers of their intracellular partners the type 2 ryanodine receptors (RyR2) which cluster on the junctional sarcoplasmic reticulum (jSR). The organization and distribution of these two groups of cardiac calcium channel clusters critically underlies the uniform contraction of the myocardium. Ca2+ signaling between these two sets of adjacent clusters produces Ca2+ sparks that in health, cannot escalate into Ca2+ waves because there is sufficient separation of adjacent clusters so that the release of Ca2+ from one RyR2 cluster or supercluster, cannot activate and sustain the release of Ca2+ from neighboring clusters. Instead, thousands of these Ca2+ release units (CRUs) generate near simultaneous Ca2+ sparks across every cardiomyocyte during the action potential when calcium induced calcium release from RyR2 is stimulated by depolarization induced Ca2+ influx through voltage dependent CaV1.2 channel clusters. These sparks summate to generate a global Ca2+ transient that activates the myofilaments and thus the electrical signal of the action potential is transduced into a functional output, myocardial contraction. To generate more, or less contractile force to match the hemodynamic and metabolic demands of the body, the heart responds to β-adrenergic signaling by altering activity of calcium channels to tune excitation-contraction coupling accordingly. Recent accumulating evidence suggests that this tuning process also involves altered expression, and dynamic reorganization of CaV1.2 and RyR2 channels on their respective membranes to control the amplitude of Ca2+ entry, SR Ca2+ release and myocardial function. In heart failure and aging, altered distribution and reorganization of these key Ca2+ signaling proteins occurs alongside architectural remodeling and is thought to contribute to impaired contractile function. In the present review we discuss these latest developments, their implications, and future questions to be addressed.
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Affiliation(s)
- Rose E Dixon
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, CA, United States
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19
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Abstract
Junctophilins (JPHs) comprise a family of structural proteins that connect the plasma membrane to intracellular organelles such as the endo/sarcoplasmic reticulum. Tethering of these membrane structures results in the formation of highly organized subcellular junctions that play important signaling roles in all excitable cell types. There are four JPH isoforms, expressed primarily in muscle and neuronal cell types. Each JPH protein consists of 6 'membrane occupation and recognition nexus' (MORN) motifs, a joining region connecting these to another set of 2 MORN motifs, a putative alpha-helical region, a divergent region exhibiting low homology between JPH isoforms, and a carboxy-terminal transmembrane region anchoring into the ER/SR membrane. JPH isoforms play essential roles in developing and maintaining subcellular membrane junctions. Conversely, inherited mutations in JPH2 cause hypertrophic or dilated cardiomyopathy, while trinucleotide expansions in the JPH3 gene cause Huntington Disease-Like 2. Loss of JPH1 protein levels can cause skeletal myopathy, while loss of cardiac JPH2 levels causes heart failure and atrial fibrillation, among other disease. This review will provide a comprehensive overview of the JPH gene family, phylogeny, and evolutionary analysis of JPH genes and other MORN domain proteins. JPH biogenesis, membrane tethering, and binding partners will be discussed, as well as functional roles of JPH isoforms in excitable cells. Finally, potential roles of JPH isoform deficits in human disease pathogenesis will be reviewed.
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Affiliation(s)
- Stephan E Lehnart
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, University Medical Center Göttingen, Department of Cardiology and Pneumology, Georg-August University Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, Texas, United States; Departments of Molecular Physiology and Biophysics, Medicine (Cardiology), Pediatrics (Cardiology), Neuroscience, and Center for Space Medicine, Baylor College of Medicine, Houston, Texas, United States
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20
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Perni S. The Builders of the Junction: Roles of Junctophilin1 and Junctophilin2 in the Assembly of the Sarcoplasmic Reticulum–Plasma Membrane Junctions in Striated Muscle. Biomolecules 2022; 12:biom12010109. [PMID: 35053257 PMCID: PMC8774113 DOI: 10.3390/biom12010109] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/06/2022] [Accepted: 01/07/2022] [Indexed: 02/06/2023] Open
Abstract
Contraction of striated muscle is triggered by a massive release of calcium from the sarcoplasmic reticulum (SR) into the cytoplasm. This intracellular calcium release is initiated by membrane depolarization, which is sensed by voltage-gated calcium channels CaV1.1 (in skeletal muscle) and CaV1.2 (in cardiac muscle) in the plasma membrane (PM), which in turn activate the calcium-releasing channel ryanodine receptor (RyR) embedded in the SR membrane. This cross-communication between channels in the PM and in the SR happens at specialized regions, the SR-PM junctions, where these two compartments come in close proximity. Junctophilin1 and Junctophilin2 are responsible for the formation and stabilization of SR-PM junctions in striated muscle and actively participate in the recruitment of the two essential players in intracellular calcium release, CaV and RyR. This short review focuses on the roles of junctophilins1 and 2 in the formation and organization of SR-PM junctions in skeletal and cardiac muscle and on the functional consequences of the absence or malfunction of these proteins in striated muscle in light of recently published data and recent advancements in protein structure prediction.
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Affiliation(s)
- Stefano Perni
- Department of Physiology and Biophysics, Anschutz Medical Campus, University of Colorado, Aurora, CO 80045, USA
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21
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Nakada T, Yamada M. [Regulation of localization and function of L-type calcium channels by junctophilins]. Nihon Yakurigaku Zasshi 2022; 157:4-8. [PMID: 34980811 DOI: 10.1254/fpj.21064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Striated muscle L-type calcium channels (LTCC) are localized specifically to the junctional membrane (JM) where the sarcolemma is closely apposed to the sarcoplasmic reticulum. Although this allocation of LTCC is critical for efficient excitation-contraction coupling in striated muscles, its underlying molecular mechanism has not been clarified. Junctophilins (JPs) stabilize the structure of JM by bridging the sarcolemmal and SR membranes. In addition, immunoprecipitation and pull-down assay revealed that the proximal C-terminus of CaV1.1 subunits directly binds to both JP1 and JP2, indicating that JPs might also directly recruit and hold LTCC in JM. Indeed, expression of a JP1 mutant lacking its C-terminus including the transmembrane domain in mouse skeletal muscles exerted a dominant-negative effect on endogenous JPs by impairing LTCC-RyR coupling at triads and reducing contractile force. To investigate a role of cardiac JP2 in a similar strategy, we injected adeno-associated virus vector expressing a C-terminus lacking JP2 mutant (JP2Δ427) driven by a cardiac troponin T promoter into C57BL/6 mice. Echocardiography recorded 4 weeks after the viral injection showed that the fractional shortening in JP2Δ427 group was significantly decreased compared to that of the control group. Calcium transient of isolated ventricular myocytes was significantly decreased by JP2Δ427 expression. Immunocytochemistry showed that JP2Δ427 recruited LTCC to the surface sarcolemma from T-tubules. Taken together, expression of C-terminus lacking JP mutants down-regulated contractile force by impairing ECC of skeletal and cardiac myocytes. Thus, the physical binding between LTCC and JP is essential for contraction of striated muscles.
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Affiliation(s)
- Tsutomu Nakada
- Department of Instrumental Analysis, Research Center for Advanced Science and Technology, Shinshu University.,Department of Molecular Pharmacology, Shinshu University School of Medicine
| | - Mitsuhiko Yamada
- Department of Molecular Pharmacology, Shinshu University School of Medicine
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22
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Gu XY, Jin B, Qi ZD, Yin XF. MicroRNA is a potential target for therapies to improve the physiological function of skeletal muscle after trauma. Neural Regen Res 2021; 17:1617-1622. [PMID: 34916449 PMCID: PMC8771090 DOI: 10.4103/1673-5374.330620] [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] [Indexed: 11/04/2022] Open
Abstract
MicroRNAs can regulate the function of ion channels in many organs. Based on our previous study we propose that miR-142a-39, which is highly expressed in denervated skeletal muscle, might affect cell excitability through similar mechanisms. In this study, we overexpressed or knocked down miR-142a-3p in C2C12 cells using a lentivirus method. After 7 days of differentiation culture, whole-cell currents were recorded. The results showed that overexpression of miR-142a-3p reduced the cell membrane capacitance, increased potassium current density and decreased calcium current density. Knockdown of miR-142a-3p reduced sodium ion channel current density. The results showed that change in miR-142a-3p expression affected the ion channel currents in C2C12 cells, suggesting its possible roles in muscle cell electrophysiology. This study was approved by the Animal Ethics Committee of Peking University in July 2020 (approval No. LA2017128).
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Affiliation(s)
- Xin-Yi Gu
- Department of Orthopedics and Traumatology, Peking University People's Hospital; Key Laboratory of Trauma and Neural Regeneration (Peking University), Beijing, China
| | - Bo Jin
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, Jiangsu Province, China
| | - Zhi-Dan Qi
- Department of Orthopedics and Traumatology, Peking University People's Hospital; Key Laboratory of Trauma and Neural Regeneration (Peking University), Beijing, China
| | - Xiao-Feng Yin
- Department of Orthopedics and Traumatology, Peking University People's Hospital; Key Laboratory of Trauma and Neural Regeneration (Peking University), Beijing, China
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23
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Jaque-Fernández F, Jorquera G, Troc-Gajardo J, Pietri-Rouxel F, Gentil C, Buvinic S, Allard B, Jaimovich E, Jacquemond V, Casas M. Pannexin-1 and CaV1.1 show reciprocal interaction during excitation-contraction and excitation-transcription coupling in skeletal muscle. J Gen Physiol 2021; 153:212695. [PMID: 34636893 PMCID: PMC8515650 DOI: 10.1085/jgp.202012635] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/24/2021] [Accepted: 09/15/2021] [Indexed: 01/18/2023] Open
Abstract
One of the most important functions of skeletal muscle is to respond to nerve stimuli by contracting. This function ensures body movement but also participates in other important physiological roles, like regulation of glucose homeostasis. Muscle activity is closely regulated to adapt to different demands and shows a plasticity that relies on both transcriptional activity and nerve stimuli. These two processes, both dependent on depolarization of the plasma membrane, have so far been regarded as separated and independent processes due to a lack of evidence of common protein partners or molecular mechanisms. In this study, we reveal intimate functional interactions between the process of excitation-induced contraction and the process of excitation-induced transcriptional activity in skeletal muscle. We show that the plasma membrane voltage-sensing protein CaV1.1 and the ATP-releasing channel Pannexin-1 (Panx1) regulate each other in a reciprocal manner, playing roles in both processes. Specifically, knockdown of CaV1.1 produces chronically elevated extracellular ATP concentrations at rest, consistent with disruption of the normal control of Panx1 activity. Conversely, knockdown of Panx1 affects not only activation of transcription but also CaV1.1 function on the control of muscle fiber contraction. Altogether, our results establish the presence of bidirectional functional regulations between the molecular machineries involved in the control of contraction and transcription induced by membrane depolarization of adult muscle fibers. Our results are important for an integrative understanding of skeletal muscle function and may impact our understanding of several neuromuscular diseases.
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Affiliation(s)
- Francisco Jaque-Fernández
- Programa de Fisiología y Biofísica, Facultad de Medicina, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile
| | - Gonzalo Jorquera
- Programa de Fisiología y Biofísica, Facultad de Medicina, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile.,Centro de Neurobiología y Fisiopatología Integrativa, Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Jennifer Troc-Gajardo
- Programa de Fisiología y Biofísica, Facultad de Medicina, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile
| | - France Pietri-Rouxel
- Université Pierre et Marie Curie, Université Paris 06, Institut National de la Santé et de la Recherche Médicale/Centre National de la Recherche Scientifique/Institut de Myologie/Centre de Recherche en Myologie, Groupement hospitalier universitaire Pitié Salpêtrière, Paris, France
| | - Christel Gentil
- Université Pierre et Marie Curie, Université Paris 06, Institut National de la Santé et de la Recherche Médicale/Centre National de la Recherche Scientifique/Institut de Myologie/Centre de Recherche en Myologie, Groupement hospitalier universitaire Pitié Salpêtrière, Paris, France
| | - Sonja Buvinic
- Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago, Chile
| | - Bruno Allard
- Université Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique UMR-5310, Institut National de la Santé et de la Recherche Médicale U-1217, Institut NeuroMyoGène, Lyon, France
| | - Enrique Jaimovich
- Programa de Fisiología y Biofísica, Facultad de Medicina, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile.,Center for Exercise, Metabolism and Cancer, Facultad de Medicina, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile
| | - Vincent Jacquemond
- Université Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique UMR-5310, Institut National de la Santé et de la Recherche Médicale U-1217, Institut NeuroMyoGène, Lyon, France
| | - Mariana Casas
- Programa de Fisiología y Biofísica, Facultad de Medicina, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile.,Center for Exercise, Metabolism and Cancer, Facultad de Medicina, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile
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24
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Piggott CA, Wu Z, Nurrish S, Xu S, Kaplan JM, Chisholm AD, Jin Y. Caenorhabditis elegans junctophilin has tissue-specific functions and regulates neurotransmission with extended-synaptotagmin. Genetics 2021; 218:iyab063. [PMID: 33871019 PMCID: PMC8864756 DOI: 10.1093/genetics/iyab063] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 04/12/2021] [Indexed: 02/06/2023] Open
Abstract
The junctophilin family of proteins tether together plasma membrane (PM) and endoplasmic reticulum (ER) membranes, and couple PM- and ER-localized calcium channels. Understanding in vivo functions of junctophilins is of great interest for dissecting the physiological roles of ER-PM contact sites. Here, we show that the sole Caenorhabditis elegans junctophilin JPH-1 localizes to discrete membrane contact sites in neurons and muscles and has important tissue-specific functions. jph-1 null mutants display slow growth and development due to weaker contraction of pharyngeal muscles, leading to reduced feeding. In the body wall muscle, JPH-1 colocalizes with the PM-localized EGL-19 voltage-gated calcium channel and ER-localized UNC-68 RyR calcium channel, and is required for animal movement. In neurons, JPH-1 colocalizes with the membrane contact site protein Extended-SYnaptoTagmin 2 (ESYT-2) in the soma, and is present near presynaptic release sites. Interestingly, jph-1 and esyt-2 null mutants display mutual suppression in their response to aldicarb, suggesting that JPH-1 and ESYT-2 have antagonistic roles in neuromuscular synaptic transmission. Additionally, we find an unexpected cell nonautonomous effect of jph-1 in axon regrowth after injury. Genetic double mutant analysis suggests that jph-1 functions in overlapping pathways with two PM-localized voltage-gated calcium channels, egl-19 and unc-2, and with unc-68 for animal health and development. Finally, we show that jph-1 regulates the colocalization of EGL-19 and UNC-68 and that unc-68 is required for JPH-1 localization to ER-PM puncta. Our data demonstrate important roles for junctophilin in cellular physiology, and also provide insights into how junctophilin functions together with other calcium channels in vivo.
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Affiliation(s)
- Christopher A Piggott
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Zilu Wu
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Stephen Nurrish
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Suhong Xu
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Joshua M Kaplan
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Andrew D Chisholm
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
- Department of Cellular and Molecular Medicine, School of Medicine, University of California San Diego, La Jolla, CA 92093, USA
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25
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Barefield DY, Sell JJ, Tahtah I, Kearns SD, McNally EM, Demonbreun AR. Loss of dysferlin or myoferlin results in differential defects in excitation-contraction coupling in mouse skeletal muscle. Sci Rep 2021; 11:15865. [PMID: 34354129 PMCID: PMC8342512 DOI: 10.1038/s41598-021-95378-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 07/26/2021] [Indexed: 11/25/2022] Open
Abstract
Muscular dystrophies are disorders characterized by progressive muscle loss and weakness that are both genotypically and phenotypically heterogenous. Progression of muscle disease arises from impaired regeneration, plasma membrane instability, defective membrane repair, and calcium mishandling. The ferlin protein family, including dysferlin and myoferlin, are calcium-binding, membrane-associated proteins that regulate membrane fusion, trafficking, and tubule formation. Mice lacking dysferlin (Dysf), myoferlin (Myof), and both dysferlin and myoferlin (Fer) on an isogenic inbred 129 background were previously demonstrated that loss of both dysferlin and myoferlin resulted in more severe muscle disease than loss of either gene alone. Furthermore, Fer mice had disordered triad organization with visibly malformed transverse tubules and sarcoplasmic reticulum, suggesting distinct roles of dysferlin and myoferlin. To assess the physiological role of disorganized triads, we now assessed excitation contraction (EC) coupling in these models. We identified differential abnormalities in EC coupling and ryanodine receptor disruption in flexor digitorum brevis myofibers isolated from ferlin mutant mice. We found that loss of dysferlin alone preserved sensitivity for EC coupling and was associated with larger ryanodine receptor clusters compared to wildtype myofibers. Loss of myoferlin alone or together with a loss of dysferlin reduced sensitivity for EC coupling, and produced disorganized and smaller ryanodine receptor cluster size compared to wildtype myofibers. These data reveal impaired EC coupling in Myof and Fer myofibers and slightly potentiated EC coupling in Dysf myofibers. Despite high homology, dysferlin and myoferlin have differential roles in regulating sarcotubular formation and maintenance resulting in unique impairments in calcium handling properties.
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Affiliation(s)
- David Y Barefield
- Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, 303 E Superior Lurie 5-500, Chicago, IL, 60611, USA. .,Department of Cell and Molecular Physiology, Loyola University Chicago, 2160 S. 1st Ave, Maywood, IL, 60153, USA.
| | - Jordan J Sell
- Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, 303 E Superior Lurie 5-500, Chicago, IL, 60611, USA
| | - Ibrahim Tahtah
- Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, 303 E Superior Lurie 5-500, Chicago, IL, 60611, USA
| | - Samuel D Kearns
- Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, 303 E Superior Lurie 5-500, Chicago, IL, 60611, USA
| | - Elizabeth M McNally
- Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, 303 E Superior Lurie 5-500, Chicago, IL, 60611, USA
| | - Alexis R Demonbreun
- Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, 303 E Superior Lurie 5-500, Chicago, IL, 60611, USA. .,Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA. .,Center for Genetic Medicine, Northwestern University, 303 E Superior Lurie 5-512, Chicago, IL, 60611, USA.
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26
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Woll KA, Van Petegem F. Calcium Release Channels: Structure and Function of IP3 Receptors and Ryanodine Receptors. Physiol Rev 2021; 102:209-268. [PMID: 34280054 DOI: 10.1152/physrev.00033.2020] [Citation(s) in RCA: 87] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Ca2+-release channels are giant membrane proteins that control the release of Ca2+ from the endoplasmic and sarcoplasmic reticulum. The two members, ryanodine receptors (RyRs) and inositol-1,4,5-trisphosphate Receptors (IP3Rs), are evolutionarily related and are both activated by cytosolic Ca2+. They share a common architecture, but RyRs have evolved additional modules in the cytosolic region. Their massive size allows for the regulation by tens of proteins and small molecules, which can affect the opening and closing of the channels. In addition to Ca2+, other major triggers include IP3 for the IP3Rs, and depolarization of the plasma membrane for a particular RyR subtype. Their size has made them popular targets for study via electron microscopic methods, with current structures culminating near 3Å. The available structures have provided many new mechanistic insights int the binding of auxiliary proteins and small molecules, how these can regulate channel opening, and the mechanisms of disease-associated mutations. They also help scrutinize previously proposed binding sites, as some of these are now incompatible with the structures. Many questions remain around the structural effects of post-translational modifications, additional binding partners, and the higher-order complexes these channels can make in situ. This review summarizes our current knowledge about the structures of Ca2+-release channels and how this informs on their function.
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Affiliation(s)
- Kellie A Woll
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
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27
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Piggott CA, Jin Y. Junctophilins: Key Membrane Tethers in Muscles and Neurons. Front Mol Neurosci 2021; 14:709390. [PMID: 34305529 PMCID: PMC8295595 DOI: 10.3389/fnmol.2021.709390] [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: 05/13/2021] [Accepted: 06/15/2021] [Indexed: 12/26/2022] Open
Abstract
Contacts between the endoplasmic reticulum (ER) and plasma membrane (PM) contain specialized tethering proteins that bind both ER and PM membranes. In excitable cells, ER–PM contacts play an important role in calcium signaling and transferring lipids. Junctophilins are a conserved family of ER–PM tethering proteins. They are predominantly expressed in muscles and neurons and known to simultaneously bind both ER- and PM-localized ion channels. Since their discovery two decades ago, functional studies using junctophilin-deficient animals have provided a deep understanding of their roles in muscles and neurons, including excitation-contraction coupling, store-operated calcium entry (SOCE), and afterhyperpolarization (AHP). In this review, we highlight key findings from mouse, fly, and worm that support evolutionary conservation of junctophilins.
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Affiliation(s)
- Christopher A Piggott
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, San Diego, CA, United States
| | - Yishi Jin
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, San Diego, CA, United States
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28
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Mareedu S, Million ED, Duan D, Babu GJ. Abnormal Calcium Handling in Duchenne Muscular Dystrophy: Mechanisms and Potential Therapies. Front Physiol 2021; 12:647010. [PMID: 33897454 PMCID: PMC8063049 DOI: 10.3389/fphys.2021.647010] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 03/02/2021] [Indexed: 12/18/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is an X-linked muscle-wasting disease caused by the loss of dystrophin. DMD is associated with muscle degeneration, necrosis, inflammation, fatty replacement, and fibrosis, resulting in muscle weakness, respiratory and cardiac failure, and premature death. There is no curative treatment. Investigations on disease-causing mechanisms offer an opportunity to identify new therapeutic targets to treat DMD. An abnormal elevation of the intracellular calcium (Cai2+) concentration in the dystrophin-deficient muscle is a major secondary event, which contributes to disease progression in DMD. Emerging studies have suggested that targeting Ca2+-handling proteins and/or mechanisms could be a promising therapeutic strategy for DMD. Here, we provide an updated overview of the mechanistic roles the sarcolemma, sarcoplasmic/endoplasmic reticulum, and mitochondria play in the abnormal and sustained elevation of Cai2+ levels and their involvement in DMD pathogenesis. We also discuss current approaches aimed at restoring Ca2+ homeostasis as potential therapies for DMD.
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Affiliation(s)
- Satvik Mareedu
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, NJ, United States
| | - Emily D Million
- Department of Molecular Microbiology and Immunology, The University of Missouri, Columbia, MO, United States
| | - Dongsheng Duan
- Department of Molecular Microbiology and Immunology, The University of Missouri, Columbia, MO, United States.,Department of Biomedical, Biological & Chemical Engineering, The University of Missouri, Columbia, MO, United States
| | - Gopal J Babu
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, NJ, United States
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29
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Perni S, Beam K. Neuronal junctophilins recruit specific Ca V and RyR isoforms to ER-PM junctions and functionally alter Ca V2.1 and Ca V2.2. eLife 2021; 10:64249. [PMID: 33769283 PMCID: PMC8046434 DOI: 10.7554/elife.64249] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 03/19/2021] [Indexed: 12/15/2022] Open
Abstract
Junctions between the endoplasmic reticulum and plasma membrane that are induced by the neuronal junctophilins are of demonstrated importance, but their molecular architecture is still poorly understood and challenging to address in neurons. This is due to the small size of the junctions and the multiple isoforms of candidate junctional proteins in different brain areas. Using colocalization of tagged proteins expressed in tsA201 cells, and electrophysiology, we compared the interactions of JPH3 and JPH4 with different calcium channels. We found that JPH3 and JPH4 caused junctional accumulation of all the tested high-voltage-activated CaV isoforms, but not a low-voltage-activated CaV. Also, JPH3 and JPH4 noticeably modify CaV2.1 and CaV2.2 inactivation rate. RyR3 moderately colocalized at junctions with JPH4, whereas RyR1 and RyR2 did not. By contrast, RyR1 and RyR3 strongly colocalized with JPH3, and RyR2 moderately. Likely contributing to this difference, JPH3 binds to cytoplasmic domain constructs of RyR1 and RyR3, but not of RyR2.
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Affiliation(s)
- Stefano Perni
- Department of Physiology and Biophysics, Anschutz Medical Campus, University of Colorado, Aurora, United States
| | - Kurt Beam
- Department of Physiology and Biophysics, Anschutz Medical Campus, University of Colorado, Aurora, United States
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30
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Hewlett B, Singh NP, Vannier C, Galli T. ER-PM Contact Sites - SNARING Actors in Emerging Functions. Front Cell Dev Biol 2021; 9:635518. [PMID: 33681218 PMCID: PMC7928305 DOI: 10.3389/fcell.2021.635518] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/21/2021] [Indexed: 11/13/2022] Open
Abstract
The compartmentalisation achieved by confining cytoplasm into membrane-enclosed organelles in eukaryotic cells is essential for maintaining vital functions including ATP production, synthetic and degradative pathways. While intracellular organelles are highly specialised in these functions, the restricting membranes also impede exchange of molecules responsible for the synchronised and responsive cellular activities. The initial identification of contact sites between the ER and plasma membrane (PM) provided a potential candidate structure for communication between organelles without mixing by fusion. Over the past decades, research has revealed a far broader picture of the events. Membrane contact sites (MCSs) have been recognized as increasingly important actors in cell differentiation, plasticity and maintenance, and, upon dysfunction, responsible for pathological conditions such as cancer and neurodegenerative diseases. Present in multiple organelles and cell types, MCSs promote transport of lipids and Ca2+ homoeostasis, with a range of associated protein families. Interestingly, each MCS displays a unique molecular signature, adapted to organelle functions. This review will explore the literature describing the molecular components and interactions taking place at ER-PM contact sites, their functions, and implications in eukaryotic cells, particularly neurons, with emphasis on lipid transfer proteins and emerging function of SNAREs.
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Affiliation(s)
- Bailey Hewlett
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Neha Pratap Singh
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Christian Vannier
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Thierry Galli
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France.,GHU PARIS Psychiatrie and Neurosciences, Paris, France
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31
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Gross P, Johnson J, Romero CM, Eaton DM, Poulet C, Sanchez-Alonso J, Lucarelli C, Ross J, Gibb AA, Garbincius JF, Lambert J, Varol E, Yang Y, Wallner M, Feldsott EA, Kubo H, Berretta RM, Yu D, Rizzo V, Elrod J, Sabri A, Gorelik J, Chen X, Houser SR. Interaction of the Joining Region in Junctophilin-2 With the L-Type Ca 2+ Channel Is Pivotal for Cardiac Dyad Assembly and Intracellular Ca 2+ Dynamics. Circ Res 2021; 128:92-114. [PMID: 33092464 PMCID: PMC7790862 DOI: 10.1161/circresaha.119.315715] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
RATIONALE Ca2+-induced Ca2+ release (CICR) in normal hearts requires close approximation of L-type calcium channels (LTCCs) within the transverse tubules (T-tubules) and RyR (ryanodine receptors) within the junctional sarcoplasmic reticulum. CICR is disrupted in cardiac hypertrophy and heart failure, which is associated with loss of T-tubules and disruption of cardiac dyads. In these conditions, LTCCs are redistributed from the T-tubules to disrupt CICR. The molecular mechanism responsible for LTCCs recruitment to and from the T-tubules is not well known. JPH (junctophilin) 2 enables close association between T-tubules and the junctional sarcoplasmic reticulum to ensure efficient CICR. JPH2 has a so-called joining region that is located near domains that interact with T-tubular plasma membrane, where LTCCs are housed. The idea that this joining region directly interacts with LTCCs and contributes to LTCC recruitment to T-tubules is unknown. OBJECTIVE To determine if the joining region in JPH2 recruits LTCCs to T-tubules through direct molecular interaction in cardiomyocytes to enable efficient CICR. METHODS AND RESULTS Modified abundance of JPH2 and redistribution of LTCC were studied in left ventricular hypertrophy in vivo and in cultured adult feline and rat ventricular myocytes. Protein-protein interaction studies showed that the joining region in JPH2 interacts with LTCC-α1C subunit and causes LTCCs distribution to the dyads, where they colocalize with RyRs. A JPH2 with induced mutations in the joining region (mutPG1JPH2) caused T-tubule remodeling and dyad loss, showing that an interaction between LTCC and JPH2 is crucial for T-tubule stabilization. mutPG1JPH2 caused asynchronous Ca2+-release with impaired excitation-contraction coupling after β-adrenergic stimulation. The disturbed Ca2+ regulation in mutPG1JPH2 overexpressing myocytes caused calcium/calmodulin-dependent kinase II activation and altered myocyte bioenergetics. CONCLUSIONS The interaction between LTCC and the joining region in JPH2 facilitates dyad assembly and maintains normal CICR in cardiomyocytes.
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MESH Headings
- Animals
- Calcium/metabolism
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Signaling
- Calcium-Calmodulin-Dependent Protein Kinase Type 2/metabolism
- Cats
- Cells, Cultured
- Disease Models, Animal
- Excitation Contraction Coupling
- Humans
- Hypertrophy, Left Ventricular/metabolism
- Hypertrophy, Left Ventricular/pathology
- Hypertrophy, Left Ventricular/physiopathology
- Kinetics
- Male
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Mitochondria, Heart/metabolism
- Mitochondria, Heart/pathology
- Muscle Proteins/genetics
- Muscle Proteins/metabolism
- Mutation
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Organelle Biogenesis
- Protein Binding
- Protein Interaction Domains and Motifs
- Rats, Sprague-Dawley
- Ryanodine Receptor Calcium Release Channel
- Rats
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Affiliation(s)
- Polina Gross
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Jaslyn Johnson
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Carlos M. Romero
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Deborah M. Eaton
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Claire Poulet
- Imperial College London, Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, London
| | - Jose Sanchez-Alonso
- Imperial College London, Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, London
| | - Carla Lucarelli
- Imperial College London, Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, London
| | - Jean Ross
- Bioimaging Center Research, Delaware Biotechnology Institute, Newark
| | - Andrew A. Gibb
- Lewis Katz Temple University School of Medicine, Center for Translational Medicine, Department of Pharmacology, Philadelphia
| | - Joanne F. Garbincius
- Lewis Katz Temple University School of Medicine, Center for Translational Medicine, Department of Pharmacology, Philadelphia
| | - Jonathan Lambert
- Lewis Katz Temple University School of Medicine, Center for Translational Medicine, Department of Pharmacology, Philadelphia
| | - Erdem Varol
- Columbia University, Center for Theoretical Neuroscience, Department of Statistics, New York, NY
| | - Yijun Yang
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Markus Wallner
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
- Medical University of Graz, Division of Cardiology, Graz, Austria
- Center for Biomarker Research in Medicine, CBmed GmbH, Graz, Austria
| | - Eric A. Feldsott
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Hajime Kubo
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Remus M. Berretta
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Daohai Yu
- Clinical Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia
| | - Victor Rizzo
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - John Elrod
- Lewis Katz Temple University School of Medicine, Center for Translational Medicine, Department of Pharmacology, Philadelphia
| | - Abdelkarim Sabri
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Julia Gorelik
- Imperial College London, Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, London
| | - Xiongwen Chen
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Steven R. Houser
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
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Luo T, Li L, Peng Y, Xie R, Yan N, Fan H, Zhang Q. The MORN domain of Junctophilin2 regulates functional interactions with small-conductance Ca 2+ -activated potassium channel subtype2 (SK2). Biofactors 2021; 47:69-79. [PMID: 31904168 DOI: 10.1002/biof.1608] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 12/17/2019] [Indexed: 01/15/2023]
Abstract
Small-conductance Ca2+ -activated K+ channel subtype2 (SK2) are stable macromolecular complexes that regulate myocardial excitability and Ca2+ homeostasis. Junctophilin-2 (JP2) is a membrane-binding protein, which provides functional crosstalk by physically linking with the cell-surface and intracellular ion channels. We previously demonstrated that the MORN domain of JP2 interacts with SK2 channels. However, the roles of the JP2 MORN domain in regulating the precise subcellular localization and molecular modulation of SK2 have not yet been incompletely understood. In the present study, in vitro and in vivo assays were used to confirm the physical interactions between the SK2 channel and JP2 in H9c2 and HEK293 cells, with a concentration on the association between the C-terminus of SK2 channels and the MORN domain of JP2. Furthermore, the membrane expression of SK2 were found to be significantly impaired by the mutation or knockdown of JP2. Using immunofluorescence staining along with Golgi/early endosome markers, we studied the mechanisms of JP2-regulated SK2 membrane trafficking, which indicates that the JP2 MORN domain is probably necessary for the retrograde trafficking of SK2 channels. The functional study demonstrates that whole cell SK2 current densities recorded from the HEK293 cells co-expressing the JP2-MORN domain with SK2 were significantly augmented, compared with cells expressing SK2 alone. Our findings suggest that the MORN domain of JP2 directly modulates SK2 channel current amplitude and trafficking, through its interaction with an overlapping region of the JP2 MORN domain on the SK2 C-terminus.
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Affiliation(s)
- Tianxia Luo
- Department of Physiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Liren Li
- Department of Physiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Yanghao Peng
- Department of Physiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Rongrong Xie
- Department of Physiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Ningning Yan
- Department of Physiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Hongkun Fan
- Department of Physiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Qian Zhang
- Department of Physiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
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Poulet C, Sanchez-Alonso J, Swiatlowska P, Mouy F, Lucarelli C, Alvarez-Laviada A, Gross P, Terracciano C, Houser S, Gorelik J. Junctophilin-2 tethers T-tubules and recruits functional L-type calcium channels to lipid rafts in adult cardiomyocytes. Cardiovasc Res 2021; 117:149-161. [PMID: 32053184 PMCID: PMC7797210 DOI: 10.1093/cvr/cvaa033] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 01/08/2020] [Accepted: 02/06/2020] [Indexed: 12/19/2022] Open
Abstract
AIM In cardiomyocytes, transverse tubules (T-tubules) associate with the sarcoplasmic reticulum (SR), forming junctional membrane complexes (JMCs) where L-type calcium channels (LTCCs) are juxtaposed to Ryanodine receptors (RyR). Junctophilin-2 (JPH2) supports the assembly of JMCs by tethering T-tubules to the SR membrane. T-tubule remodelling in cardiac diseases is associated with downregulation of JPH2 expression suggesting that JPH2 plays a crucial role in T-tubule stability. Furthermore, increasing evidence indicate that JPH2 might additionally act as a modulator of calcium signalling by directly regulating RyR and LTCCs. This study aimed at determining whether JPH2 overexpression restores normal T-tubule structure and LTCC function in cultured cardiomyocytes. METHODS AND RESULTS Rat ventricular myocytes kept in culture for 4 days showed extensive T-tubule remodelling with impaired JPH2 localization and relocation of the scaffolding protein Caveolin3 (Cav3) from the T-tubules to the outer membrane. Overexpression of JPH2 restored T-tubule structure and Cav3 relocation. Depletion of membrane cholesterol by chronic treatment with methyl-β-cyclodextrin (MβCD) countered the stabilizing effect of JPH2 overexpression on T-tubules and Cav3. Super-resolution scanning patch-clamp showed that JPH2 overexpression greatly increased the number of functional LTCCs at the plasma membrane. Treatment with MβCD reduced LTCC open probability and activity. Proximity ligation assays showed that MβCD did not affect JPH2 interaction with RyR and the pore-forming LTCC subunit Cav1.2, but strongly impaired JPH2 association with Cav3 and the accessory LTCC subunit Cavβ2. CONCLUSIONS JPH2 promotes T-tubule structural stability and recruits functional LTCCs to the membrane, most likely by directly binding to the channel. Cholesterol is involved in the binding of JPH2 to T-tubules as well as in the modulation of LTCC activity. We propose a model where cholesterol and Cav3 support the assembly of lipid rafts which provide an anchor for JPH2 to form JMCs and a platform for signalling complexes to regulate LTCC activity.
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Affiliation(s)
- Claire Poulet
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Jose Sanchez-Alonso
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Pamela Swiatlowska
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Florence Mouy
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Carla Lucarelli
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London W12 0NN, UK
- Department of Cardiac Surgery, School of Medicine, University of Verona, Piazzale L.A. Scuro 10, 37134 Verona, Italy
| | - Anita Alvarez-Laviada
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Polina Gross
- Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, 3500 N. Broad St., Philadelphia, PA 19140, USA
| | - Cesare Terracciano
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Steven Houser
- Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, 3500 N. Broad St., Philadelphia, PA 19140, USA
| | - Julia Gorelik
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London W12 0NN, UK
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34
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Meizoso-Huesca A, Launikonis BS. The Orai1 inhibitor BTP2 has multiple effects on Ca2+ handling in skeletal muscle. J Gen Physiol 2020; 153:211591. [PMID: 33316029 PMCID: PMC7735889 DOI: 10.1085/jgp.202012747] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 10/21/2020] [Accepted: 11/17/2020] [Indexed: 12/15/2022] Open
Abstract
BTP2 is an inhibitor of the Ca2+ channel Orai1, which mediates store-operated Ca2+ entry (SOCE). Despite having been extensively used in skeletal muscle, the effects of this inhibitor on Ca2+ handling in muscle cells have not been described. To address this question, we used intra- and extracellular application of BTP2 in mechanically skinned fibers and developed a localized modulator application approach, which provided in-preparation reference and test fiber sections to enhance detection of the effect of Ca2+ handling modulators. In addition to blocking Orai1-dependent SOCE, we found a BTP2-dependent inhibition of resting extracellular Ca2+ flux. Increasing concentrations of BTP2 caused a shift from inducing accumulation of Ca2+ in the t-system due to Orai1 blocking to reducing the resting [Ca2+] in the sealed t-system. This effect was not observed in the absence of functional ryanodine receptors (RYRs), suggesting that higher concentrations of BTP2 impair RYR function. Additionally, we found that BTP2 impaired action potential–induced Ca2+ release from the sarcoplasmic reticulum during repetitive stimulation without compromising the fiber Ca2+ content. BTP2 was found to have an effect on RYR-mediated Ca2+ release, suggesting that RYR is the point of BTP2-induced inhibition during cycles of EC coupling. The effects of BTP2 on the RYR Ca2+ leak and release were abolished by pre-exposure to saponin, indicating that the effects of BTP2 on the RYR are not direct and require a functional t-system. Our results demonstrate the presence of a SOCE channels–mediated basal Ca2+ influx in healthy muscle fibers and indicate that BTP2 has multiple effects on Ca2+ handling, including indirect effects on the activity of the RYR.
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Affiliation(s)
- Aldo Meizoso-Huesca
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Bradley S Launikonis
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
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Sajko S, Grishkovskaya I, Kostan J, Graewert M, Setiawan K, Trübestein L, Niedermüller K, Gehin C, Sponga A, Puchinger M, Gavin AC, Leonard TA, Svergun DI, Smith TK, Morriswood B, Djinovic-Carugo K. Structures of three MORN repeat proteins and a re-evaluation of the proposed lipid-binding properties of MORN repeats. PLoS One 2020; 15:e0242677. [PMID: 33296386 PMCID: PMC7725318 DOI: 10.1371/journal.pone.0242677] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 11/08/2020] [Indexed: 11/19/2022] Open
Abstract
MORN (Membrane Occupation and Recognition Nexus) repeat proteins have a wide taxonomic distribution, being found in both prokaryotes and eukaryotes. Despite this ubiquity, they remain poorly characterised at both a structural and a functional level compared to other common repeats. In functional terms, they are often assumed to be lipid-binding modules that mediate membrane targeting. We addressed this putative activity by focusing on a protein composed solely of MORN repeats-Trypanosoma brucei MORN1. Surprisingly, no evidence for binding to membranes or lipid vesicles by TbMORN1 could be obtained either in vivo or in vitro. Conversely, TbMORN1 did interact with individual phospholipids. High- and low-resolution structures of the MORN1 protein from Trypanosoma brucei and homologous proteins from the parasites Toxoplasma gondii and Plasmodium falciparum were obtained using a combination of macromolecular crystallography, small-angle X-ray scattering, and electron microscopy. This enabled a first structure-based definition of the MORN repeat itself. Furthermore, all three structures dimerised via their C-termini in an antiparallel configuration. The dimers could form extended or V-shaped quaternary structures depending on the presence of specific interface residues. This work provides a new perspective on MORN repeats, showing that they are protein-protein interaction modules capable of mediating both dimerisation and oligomerisation.
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Affiliation(s)
- Sara Sajko
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Irina Grishkovskaya
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Julius Kostan
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Melissa Graewert
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Kim Setiawan
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Linda Trübestein
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Korbinian Niedermüller
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Charlotte Gehin
- European Molecular Biology Laboratory, Heidelberg Unit, Heidelberg, Germany
- Institute of Bioengineering, Laboratory of Lipid Cell Biology, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Antonio Sponga
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Martin Puchinger
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Anne-Claude Gavin
- European Molecular Biology Laboratory, Heidelberg Unit, Heidelberg, Germany
- Department for Cell Physiology and Metabolism, University of Geneva, Centre Medical Universitaire, Geneva, Switzerland
| | - Thomas A. Leonard
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | | | - Terry K. Smith
- School of Biology, BSRC, University of St. Andrews, St. Andrews, United Kingdom
| | - Brooke Morriswood
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Kristina Djinovic-Carugo
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
- Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
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Effects of miR-34c-5p on Sodium, Potassium, and Calcium Channel Currents in C2C12 Myotubes. Cell Mol Neurobiol 2020; 40:1223-1230. [PMID: 32100187 DOI: 10.1007/s10571-020-00810-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 02/04/2020] [Indexed: 10/24/2022]
Abstract
The aim of this study was to investigate the effects of miR-34c-5p on the main voltage-dependent ion channels in skeletal muscle cells. This study focused on the effects of miR-34c-5p on sodium, potassium, and calcium currents in C2C12 myoblasts. The miR-34c-5p overexpression group, knockdown group, and control group were differentiated for 7 days, fused into myotubes, and used for the whole-cell patch clamp recording. Compared with the control group, the whole-cell sodium current density of the other two groups had no significant changes. In the knockdown group, the delayed rectifier potassium current density was increased (statistically significant), and the whole-cell calcium channel current density did not change. In the overexpression group, the change of rectifier potassium current density was not obvious, while the peak calcium channel current density increased (- 9.23 ± 0.95 pA/pF, n = 6 cells for the overexpression group vs. - 6.48 ± 0.64 pA/pF, n = 7 cells for the control; p < 0.05). Changes in the expression of miR-34c-5p can affect the electrophysiological characteristics of calcium and potassium voltage-gated channels in C2C12 myotubes. Overexpression of miR-34c-5p increased whole-cell L-type calcium channel current (ICa,L), while miR-34c-5p knockdown increased whole-cell delayed rectifier potassium current (IKd).
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Ogawa H, Kurebayashi N, Yamazawa T, Murayama T. Regulatory mechanisms of ryanodine receptor/Ca 2+ release channel revealed by recent advancements in structural studies. J Muscle Res Cell Motil 2020; 42:291-304. [PMID: 32040690 PMCID: PMC8332584 DOI: 10.1007/s10974-020-09575-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 02/05/2020] [Indexed: 02/07/2023]
Abstract
Ryanodine receptors (RyRs) are huge homotetrameric Ca2+ release channels localized to the sarcoplasmic reticulum. RyRs are responsible for the release of Ca2+ from the SR during excitation–contraction coupling in striated muscle cells. Recent revolutionary advancements in cryo-electron microscopy have provided a number of near-atomic structures of RyRs, which have enabled us to better understand the architecture of RyRs. Thus, we are now in a new era understanding the gating, regulatory and disease-causing mechanisms of RyRs. Here we review recent advances in the elucidation of the structures of RyRs, especially RyR1 in skeletal muscle, and their mechanisms of regulation by small molecules, associated proteins and disease-causing mutations.
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Affiliation(s)
- Haruo Ogawa
- Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, 113-0032, Japan.
| | - Nagomi Kurebayashi
- Department of Pharmacology, Juntendo University School of Medicine, Tokyo, 113-8421, Japan
| | - Toshiko Yamazawa
- Department of Molecular Physiology, The Jikei University School of Medicine, Tokyo, 105-8461, Japan
| | - Takashi Murayama
- Department of Pharmacology, Juntendo University School of Medicine, Tokyo, 113-8421, Japan
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Shishmarev D. Excitation-contraction coupling in skeletal muscle: recent progress and unanswered questions. Biophys Rev 2020; 12:143-153. [PMID: 31950344 DOI: 10.1007/s12551-020-00610-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 01/03/2020] [Indexed: 02/07/2023] Open
Abstract
Excitation-contraction coupling (ECC) is a physiological process that links excitation of muscles by the nervous system to their mechanical contraction. In skeletal muscle, ECC is initiated with an action potential, generated by the somatic nervous system, which causes a depolarisation of the muscle fibre membrane (sarcolemma). This leads to a rapid change in the transmembrane potential, which is detected by the voltage-gated Ca2+ channel dihydropyridine receptor (DHPR) embedded in the sarcolemma. DHPR transmits the contractile signal to another Ca2+ channel, ryanodine receptor (RyR1), embedded in the membrane of the sarcoplasmic reticulum (SR), which releases a large amount of Ca2+ ions from the SR that initiate muscle contraction. Despite the fundamental role of ECC in skeletal muscle function of all vertebrate species, the molecular mechanism underpinning the communication between the two key proteins involved in the process (DHPR and RyR1) is still largely unknown. The goal of this work is to review the recent progress in our understanding of ECC in skeletal muscle from the point of view of the structure and interactions of proteins involved in the process, and to highlight the unanswered questions in the field.
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Affiliation(s)
- Dmitry Shishmarev
- John Curtin School of Medical Research, The Australian National University, Canberra, ACT, 2601, Australia.
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Mackrill JJ, Shiels HA. Evolution of Excitation-Contraction Coupling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:281-320. [DOI: 10.1007/978-3-030-12457-1_12] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Ca 2+ Channels Mediate Bidirectional Signaling between Sarcolemma and Sarcoplasmic Reticulum in Muscle Cells. Cells 2019; 9:cells9010055. [PMID: 31878335 PMCID: PMC7016941 DOI: 10.3390/cells9010055] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 12/19/2019] [Accepted: 12/23/2019] [Indexed: 12/21/2022] Open
Abstract
The skeletal muscle and myocardial cells present highly specialized structures; for example, the close interaction between the sarcoplasmic reticulum (SR) and mitochondria—responsible for excitation-metabolism coupling—and the junction that connects the SR with T-tubules, critical for excitation-contraction (EC) coupling. The mechanisms that underlie EC coupling in these two cell types, however, are fundamentally distinct. They involve the differential expression of Ca2+ channel subtypes: CaV1.1 and RyR1 (skeletal), vs. CaV1.2 and RyR2 (cardiac). The CaV channels transform action potentials into elevations of cytosolic Ca2+, by activating RyRs and thus promoting SR Ca2+ release. The high levels of Ca2+, in turn, stimulate not only the contractile machinery but also the generation of mitochondrial reactive oxygen species (ROS). This forward signaling is reciprocally regulated by the following feedback mechanisms: Ca2+-dependent inactivation (of Ca2+ channels), the recruitment of Na+/Ca2+ exchanger activity, and oxidative changes in ion channels and transporters. Here, we summarize both well-established concepts and recent advances that have contributed to a better understanding of the molecular mechanisms involved in this bidirectional signaling.
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Junctophilin Proteins Tether a Cav1-RyR2-KCa3.1 Tripartite Complex to Regulate Neuronal Excitability. Cell Rep 2019; 28:2427-2442.e6. [DOI: 10.1016/j.celrep.2019.07.075] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/20/2019] [Accepted: 07/19/2019] [Indexed: 12/12/2022] Open
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Molecular determinants of homo- and heteromeric interactions of Junctophilin-1 at triads in adult skeletal muscle fibers. Proc Natl Acad Sci U S A 2019; 116:15716-15724. [PMID: 31315980 DOI: 10.1073/pnas.1820980116] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In adult skeletal muscles, 2 junctophilin isoforms (JPH1 and JPH2) tether the sarcoplasmic reticulum (SR) to transverse tubule (T-tubule) membranes, generating stable membrane contact sites known as triads. JPHs are anchored to the membrane of the SR by a C-terminal transmembrane domain (TMD) and bind the T-tubule membrane through their cytosolic N-terminal region, which contains 8 lipid-binding (MORN) motifs. By combining expression of GFP-JPH1 deletion mutants in skeletal muscle fibers with in vitro biochemical experiments, we investigated the molecular determinants of JPH1 recruitment at triads in adult skeletal muscle fibers. We found that MORN motifs bind PI(4,5)P2 in the sarcolemma, but do not mediate the selective localization of JPH1 at the T-tubule compartment of triads. On the contrary, fusion proteins containing only the TMD of JPH1 were able to localize at the junctional SR compartment of the triad. Bimolecular fluorescence complementation experiments indicated that the TMD of JPH1 can form dimers, suggesting that the observed localization at triads may result from dimerization with the TMDs of resident JPH1. A second domain, capable of mediating homo- and heterodimeric interactions between JPH1 and JPH2 was identified in the cytosolic region. FRAP experiments revealed that removal of either one of these 2 domains in JPH1 decreases the association of the resulting mutant proteins with triads. Altogether, these results suggest that the ability to establish homo- and heterodimeric interactions with resident JPHs may support the recruitment and stability of newly synthesized JPHs at triads in adult skeletal muscle fibers.
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Saeki T, Suzuki Y, Yamamura H, Takeshima H, Imaizumi Y. A junctophilin-caveolin interaction enables efficient coupling between ryanodine receptors and BK Ca channels in the Ca 2+ microdomain of vascular smooth muscle. J Biol Chem 2019; 294:13093-13105. [PMID: 31308177 PMCID: PMC6721949 DOI: 10.1074/jbc.ra119.008342] [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] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 07/09/2019] [Indexed: 01/09/2023] Open
Abstract
Functional coupling between large-conductance Ca2+-activated K+ (BKCa) channels in the plasma membrane (PM) and ryanodine receptors (RyRs) in the sarcoplasmic reticulum (SR) is an essential mechanism for regulating mechanical force in most smooth muscle (SM) tissues. Spontaneous Ca2+ release through RyRs (Ca2+ sparks) and subsequent BKCa channel activation occur within the PM-SR junctional sites. We report here that a molecular interaction of caveolin-1 (Cav1), a caveola-forming protein, with junctophilin-2 (JP2), a bridging protein between PM and SR, positions BKCa channels near RyRs in SM cells (SMCs) and thereby contributes to the formation of a molecular complex essential for Ca2+ microdomain function. Approximately half of all Ca2+ sparks occurred within a close distance (<400 nm) from fluorescently labeled JP2 or Cav1 particles, when they were moderately expressed in primary SMCs from mouse mesenteric artery. The removal of caveolae by genetic Cav1 ablation or methyl-β-cyclodextrin treatments significantly reduced coupling efficiency between Ca2+ sparks and BKCa channel activity in SMCs, an effect also observed after JP2 knockdown in SMCs. A 20-amino acid-long region in JP2 appeared to be essential for the observed JP2-Cav1 interaction, and we also observed an interaction between JP2 and the BKCa channel. It can be concluded that the JP2-Cav1 interaction provides a structural and functional basis for the Ca2+ microdomain at PM-SR junctions and mediates cross-talk between RyRs and BKCa channels, converts local Ca2+ sparks into membrane hyperpolarization, and contributes to stabilizing resting tone in SMCs.
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Affiliation(s)
- Takanori Saeki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Yoshiaki Suzuki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Hisao Yamamura
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Hiroshi Takeshima
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Yuji Imaizumi
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan.
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Jiang J, Tang M, Huang Z, Chen L. Junctophilins emerge as novel therapeutic targets. J Cell Physiol 2019; 234:16933-16943. [DOI: 10.1002/jcp.28405] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 01/25/2019] [Accepted: 01/30/2019] [Indexed: 12/24/2022]
Affiliation(s)
- Jinyong Jiang
- Institute of Pharmacy and Pharmacology, Learning Key Laboratory for Pharmacoproteomics, Hunan Province Cooperative Innovation Center for Molecular Target New Drugs Study University of South China Hengyang China
| | - Mingzhu Tang
- Institute of Pharmacy and Pharmacology, Learning Key Laboratory for Pharmacoproteomics, Hunan Province Cooperative Innovation Center for Molecular Target New Drugs Study University of South China Hengyang China
| | - Zhen Huang
- Institute of Pharmacy and Pharmacology, Learning Key Laboratory for Pharmacoproteomics, Hunan Province Cooperative Innovation Center for Molecular Target New Drugs Study University of South China Hengyang China
| | - Linxi Chen
- Institute of Pharmacy and Pharmacology, Learning Key Laboratory for Pharmacoproteomics, Hunan Province Cooperative Innovation Center for Molecular Target New Drugs Study University of South China Hengyang China
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