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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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Murzilli S, Serano M, Pietrangelo L, Protasi F, Paolini C. Structural Adaptation of the Excitation-Contraction Coupling Apparatus in Calsequestrin1-Null Mice during Postnatal Development. BIOLOGY 2023; 12:1064. [PMID: 37626950 PMCID: PMC10452101 DOI: 10.3390/biology12081064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/21/2023] [Accepted: 07/26/2023] [Indexed: 08/27/2023]
Abstract
The precise arrangement and peculiar interaction of transverse tubule (T-tubule) and sarcoplasmic reticulum (SR) membranes efficiently guarantee adequate contractile properties of skeletal muscle fibers. Fast muscle fibers from mice lacking calsequestrin 1 (CASQ1) are characterized by the profound ultrastructural remodeling of T-tubule/SR junctions. This study investigates the role of CASQ1, an essential component of calcium release units (CRUs), in the postnatal development of muscle fibers. By using CASQ1-knockout mice, we examined the maturation of CRUs and the involvement of different junctional proteins in the juxtaposition of the membrane system. Our morphological investigation of both wild-type (WT) and CASQ1-null extensor digitorum longus (EDL) fibers, from 1 week to 4 months of age, yielded noteworthy findings. Firstly, we observed that the absence of CASQ1 hindered the full maturation of CRUs, despite the correct localization of key junctional components (ryanodine receptor, dihydropyridine receptor, and triadin) to the junctional SR in adult animals. Furthermore, analysis of protein expression profiles related to T-tubule biogenesis and organization (junctophilin 1, amphiphysin 2, caveolin 3, and mitsugumin 29) demonstrated delayed progression in their expression during postnatal development in the absence of CASQ1, suggesting the impaired maturation of CRUs. The absence of CASQ1 directly impacts the proper assembly of CRUs during development and influences the expression and coordination of other proteins involved in T-tubule biogenesis and organization.
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Affiliation(s)
- Stefania Murzilli
- Department of Neuroscience, Imaging and Clinical Sciences (DNISC), Center for Advanced Studies and Technology (CAST), University G. d’Annunzio of Chieti-Pescara, 66100 Chieti, Italy;
| | - Matteo Serano
- Department of Medicine and Aging Sciences (DMSI), Center for Advanced Studies and Technology (CAST), University G. d’Annunzio of Chieti-Pescara, 66100 Chieti, Italy; (M.S.); (L.P.); (F.P.)
| | - Laura Pietrangelo
- Department of Medicine and Aging Sciences (DMSI), Center for Advanced Studies and Technology (CAST), University G. d’Annunzio of Chieti-Pescara, 66100 Chieti, Italy; (M.S.); (L.P.); (F.P.)
| | - Feliciano Protasi
- Department of Medicine and Aging Sciences (DMSI), Center for Advanced Studies and Technology (CAST), University G. d’Annunzio of Chieti-Pescara, 66100 Chieti, Italy; (M.S.); (L.P.); (F.P.)
| | - Cecilia Paolini
- Department of Neuroscience, Imaging and Clinical Sciences (DNISC), Center for Advanced Studies and Technology (CAST), University G. d’Annunzio of Chieti-Pescara, 66100 Chieti, Italy;
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Nakamura J, Maruyama Y, Tajima G, Hayakawa S, Suwa M, Sato C. Ca 2+ Dependent Formation/Collapse of Cylindrical Ca 2+-ATPase Crystals in Scallop Sarcoplasmic Reticulum (SR) Vesicles: A Possible Dynamic Role of SR in Regulation of Muscle Contraction. Int J Mol Sci 2023; 24:ijms24087080. [PMID: 37108240 PMCID: PMC10139091 DOI: 10.3390/ijms24087080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 03/28/2023] [Accepted: 03/29/2023] [Indexed: 04/29/2023] Open
Abstract
[Ca2+]-dependent crystallization of the Ca2+-ATPase molecules in sarcoplasmic reticulum (SR) vesicles isolated from scallop striated muscle elongated the vesicles in the absence of ATP, and ATP stabilized the crystals. Here, to determine the [Ca2+]-dependence of vesicle elongation in the presence of ATP, SR vesicles in various [Ca2+] environments were imaged using negative stain electron microscopy. The images obtained revealed the following phenomena. (i) Crystal-containing elongated vesicles appeared at ≤1.4 µM Ca2+ and almost disappeared at ≥18 µM Ca2+, where ATPase activity reaches its maximum. (ii) At ≥18 µM Ca2+, almost all SR vesicles were in the round form and covered by tightly clustered ATPase crystal patches. (iii) Round vesicles dried on electron microscopy grids occasionally had cracks, probably because surface tension crushed the solid three-dimensional spheres. (iv) [Ca2+]-dependent ATPase crystallization was rapid (<1 min) and reversible. These data prompt the hypothesis that SR vesicles autonomously elongate or contract with the help of a calcium-sensitive ATPase network/endoskeleton and that ATPase crystallization may modulate physical properties of the SR architecture, including the ryanodine receptors that control muscle contraction.
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Affiliation(s)
- Jun Nakamura
- Health and Medical Institute, National Institute of Advanced Industrial Science and Technology, Central 6, 1-1-4 Umezono, Tsukuba 305-8568, Japan
| | - Yuusuke Maruyama
- Health and Medical Institute, National Institute of Advanced Industrial Science and Technology, Central 6, 1-1-4 Umezono, Tsukuba 305-8568, Japan
| | - Genichi Tajima
- Institute for Excellence in Higher Education, Tohoku University, 41 Kawauchi, Aoba-ku, Sendai 980-8576, Japan
| | - Satoshi Hayakawa
- Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamimachi, Itabashi, Tokyo 173-8610, Japan
| | - Makiko Suwa
- Biological Science Course, Graduate School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuou-ku, Sagamihara 252-5258, Japan
| | - Chikara Sato
- Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamimachi, Itabashi, Tokyo 173-8610, Japan
- Biological Science Course, Graduate School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuou-ku, Sagamihara 252-5258, Japan
- Division of Immune Homeostasis, Department of Pathology and Microbiology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamimachi, Itabashi, Tokyo 173-8610, Japan
- School of Integrative and Global Majors (SIGMA), University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8577, Japan
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Protasi F, Girolami B, Serano M, Pietrangelo L, Paolini C. Ablation of Calsequestrin-1, Ca 2+ unbalance, and susceptibility to heat stroke. Front Physiol 2022; 13:1033300. [PMID: 36311237 PMCID: PMC9598425 DOI: 10.3389/fphys.2022.1033300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 09/20/2022] [Indexed: 12/05/2022] Open
Abstract
Introduction: Ca2+ levels in adult skeletal muscle fibers are mainly controlled by excitation-contraction (EC) coupling, a mechanism that translates action potentials in release of Ca2+ from the sarcoplasmic reticulum (SR) release channels, i.e. the ryanodine receptors type-1 (RyR1). Calsequestrin (Casq) is a protein that binds large amounts of Ca2+ in the lumen of the SR terminal cisternae, near sites of Ca2+ release. There is general agreement that Casq is not only important for the SR ability to store Ca2+, but also for modulating the opening probability of the RyR Ca2+ release channels. The initial studies: About 20 years ago we generated a mouse model lacking Casq1 (Casq1-null mice), the isoform predominantly expressed in adult fast twitch skeletal muscle. While the knockout was not lethal as expected, lack of Casq1 caused a striking remodeling of membranes of SR and of transverse tubules (TTs), and mitochondrial damage. Functionally, CASQ1-knockout resulted in reduced SR Ca2+ content, smaller Ca2+ transients, and severe SR depletion during repetitive stimulation. The myopathic phenotype of Casq1-null mice: After the initial studies, we discovered that Casq1-null mice were prone to sudden death when exposed to halogenated anaesthetics, heat and even strenuous exercise. These syndromes are similar to human malignant hyperthermia susceptibility (MHS) and environmental-exertional heat stroke (HS). We learned that mechanisms underlying these syndromes involved excessive SR Ca2+ leak and excessive production of oxidative species: indeed, mortality and mitochondrial damage were significantly prevented by administration of antioxidants and reduction of oxidative stress. Though, how Casq1-null mice could survive without the most important SR Ca2+ binding protein was a puzzling issue that was not solved. Unravelling the mystery: The mystery was finally solved in 2020, when we discovered that in Casq1-null mice the SR undergoes adaptations that result in constitutively active store-operated Ca2+ entry (SOCE). SOCE is a mechanism that allows skeletal fibers to use external Ca2+ when SR stores are depleted. The post-natal compensatory mechanism that allows Casq1-null mice to survive involves the assembly of new SR-TT junctions (named Ca2+ entry units) containing Stim1 and Orai1, the two proteins that mediate SOCE.
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Affiliation(s)
- Feliciano Protasi
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
- Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
| | - Barbara Girolami
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
- Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
| | - Matteo Serano
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
- Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
| | - Laura Pietrangelo
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
- Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
| | - Cecilia Paolini
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
- Department of Neuroscience, Imaging and Clinical Sciences, University G. d’Annunzio of Chieti-Pescara, Chieti, Italy
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Gros K, Matkovič U, Parato G, Miš K, Luin E, Bernareggi A, Sciancalepore M, Marš T, Lorenzon P, Pirkmajer S. Neuronal Agrin Promotes Proliferation of Primary Human Myoblasts in an Age-Dependent Manner. Int J Mol Sci 2022; 23:ijms231911784. [PMID: 36233091 PMCID: PMC9570459 DOI: 10.3390/ijms231911784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/06/2022] [Accepted: 09/22/2022] [Indexed: 12/02/2022] Open
Abstract
Neuronal agrin, a heparan sulphate proteoglycan secreted by the α-motor neurons, promotes the formation and maintenance of the neuromuscular junction by binding to Lrp4 and activating muscle-specific kinase (MuSK). Neuronal agrin also promotes myogenesis by enhancing differentiation and maturation of myotubes, but its effect on proliferating human myoblasts, which are often considered to be unresponsive to agrin, remains unclear. Using primary human myoblasts, we determined that neuronal agrin induced transient dephosphorylation of ERK1/2, while c-Abl, STAT3, and focal adhesion kinase were unresponsive. Gene silencing of Lrp4 and MuSK markedly reduced the BrdU incorporation, suggesting the functional importance of the Lrp4/MuSK complex for myoblast proliferation. Acute and chronic treatments with neuronal agrin increased the proliferation of human myoblasts in old donors, but they did not affect the proliferation of myoblasts in young donors. The C-terminal fragment of agrin which lacks the Lrp4-binding site and cannot activate MuSK had a similar age-dependent effect, indicating that the age-dependent signalling pathways activated by neuronal agrin involve the Lrp4/MuSK receptor complex as well as an Lrp4/MuSK-independent pathway which remained unknown. Collectively, our results highlight an age-dependent role for neuronal agrin in promoting the proliferation of human myoblasts.
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Affiliation(s)
- Katarina Gros
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Urška Matkovič
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Giulia Parato
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
- The B.R.A.I.N. Centre for Neuroscience, University of Trieste, 34127 Trieste, Italy
| | - Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Elisa Luin
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
- The B.R.A.I.N. Centre for Neuroscience, University of Trieste, 34127 Trieste, Italy
| | - Annalisa Bernareggi
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
- The B.R.A.I.N. Centre for Neuroscience, University of Trieste, 34127 Trieste, Italy
| | - Marina Sciancalepore
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
- The B.R.A.I.N. Centre for Neuroscience, University of Trieste, 34127 Trieste, Italy
| | - Tomaž Marš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Paola Lorenzon
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
- The B.R.A.I.N. Centre for Neuroscience, University of Trieste, 34127 Trieste, Italy
- Correspondence: (P.L.); (S.P.)
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
- Correspondence: (P.L.); (S.P.)
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Store-Operated Ca 2+ Entry in Skeletal Muscle Contributes to the Increase in Body Temperature during Exertional Stress. Int J Mol Sci 2022; 23:ijms23073772. [PMID: 35409132 PMCID: PMC8998704 DOI: 10.3390/ijms23073772] [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: 02/24/2022] [Revised: 03/26/2022] [Accepted: 03/26/2022] [Indexed: 12/15/2022] Open
Abstract
Exertional heat stroke (HS) is a hyperthermic crisis triggered by an excessive accumulation of Ca2+ in skeletal muscle fibers. We demonstrated that exercise leads to the formation of calcium entry units (CEUs), which are intracellular junctions that reduce muscle fatigue by promoting the recovery of extracellular Ca2+ via store-operated Ca2+ entry (SOCE). Here, we tested the hypothesis that exercise-induced assembly of CEUs may increase the risk of HS when physical activity is performed in adverse environmental conditions (high temperature and humidity). Adult mice were: (a) first, divided into three experimental groups: control, trained-1 month (voluntary running in wheel cages), and acutely exercised-1 h (incremental treadmill run); and (b) then subjected to an exertional stress (ES) protocol, a treadmill run in an environmental chamber at 34 °C and 40% humidity. The internal temperature of the mice at the end of the ES was higher in both pre-exercised groups. During an ES ex-vivo protocol, extensor digitorum longus(EDL) muscles from the trained-1 month and exercised-1 h mice generated greater basal tension than in the control and were those that contained a greater number of CEUs, assessed by electron microscopy. The data collected suggest that the entry of Ca2+ from extracellular space via CEUs could contribute to exertional HS when exercise is performed in adverse environmental conditions.
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Protasi F, Pietrangelo L, Boncompagni S. Improper Remodeling of Organelles Deputed to Ca 2+ Handling and Aerobic ATP Production Underlies Muscle Dysfunction in Ageing. Int J Mol Sci 2021; 22:6195. [PMID: 34201319 PMCID: PMC8228829 DOI: 10.3390/ijms22126195] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 12/28/2022] Open
Abstract
Proper skeletal muscle function is controlled by intracellular Ca2+ concentration and by efficient production of energy (ATP), which, in turn, depend on: (a) the release and re-uptake of Ca2+ from sarcoplasmic-reticulum (SR) during excitation-contraction (EC) coupling, which controls the contraction and relaxation of sarcomeres; (b) the uptake of Ca2+ into the mitochondrial matrix, which stimulates aerobic ATP production; and finally (c) the entry of Ca2+ from the extracellular space via store-operated Ca2+ entry (SOCE), a mechanism that is important to limit/delay muscle fatigue. Abnormalities in Ca2+ handling underlie many physio-pathological conditions, including dysfunction in ageing. The specific focus of this review is to discuss the importance of the proper architecture of organelles and membrane systems involved in the mechanisms introduced above for the correct skeletal muscle function. We reviewed the existing literature about EC coupling, mitochondrial Ca2+ uptake, SOCE and about the structural membranes and organelles deputed to those functions and finally, we summarized the data collected in different, but complementary, projects studying changes caused by denervation and ageing to the structure and positioning of those organelles: a. denervation of muscle fibers-an event that contributes, to some degree, to muscle loss in ageing (known as sarcopenia)-causes misplacement and damage: (i) of membrane structures involved in EC coupling (calcium release units, CRUs) and (ii) of the mitochondrial network; b. sedentary ageing causes partial disarray/damage of CRUs and of calcium entry units (CEUs, structures involved in SOCE) and loss/misplacement of mitochondria; c. functional electrical stimulation (FES) and regular exercise promote the rescue/maintenance of the proper architecture of CRUs, CEUs, and of mitochondria in both denervation and ageing. All these structural changes were accompanied by related functional changes, i.e., loss/decay in function caused by denervation and ageing, and improved function following FES or exercise. These data suggest that the integrity and proper disposition of intracellular organelles deputed to Ca2+ handling and aerobic generation of ATP is challenged by inactivity (or reduced activity); modifications in the architecture of these intracellular membrane systems may contribute to muscle dysfunction in ageing and sarcopenia.
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Affiliation(s)
- Feliciano Protasi
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy; (L.P.); (S.B.)
- DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
| | - Laura Pietrangelo
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy; (L.P.); (S.B.)
- DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
| | - Simona Boncompagni
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy; (L.P.); (S.B.)
- DNICS, Department of Neuroscience and Clinical Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
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Boncompagni S, Pecorai C, Michelucci A, Pietrangelo L, Protasi F. Long-Term Exercise Reduces Formation of Tubular Aggregates and Promotes Maintenance of Ca 2+ Entry Units in Aged Muscle. Front Physiol 2021; 11:601057. [PMID: 33469430 PMCID: PMC7813885 DOI: 10.3389/fphys.2020.601057] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/16/2020] [Indexed: 12/16/2022] Open
Abstract
Tubular aggregates (TAs) in skeletal muscle fibers are unusual accumulation of sarcoplasmic reticulum (SR) tubes that are found in different disorders including TA myopathy (TAM). TAM is a muscular disease characterized by muscle pain, cramping, and weakness that has been recently linked to mutations in STIM1 and ORAI1. STIM1 and ORAI1 are the two main proteins mediating store-operated Ca2+ entry (SOCE), a mechanism activated by depletion of intracellular Ca2+ stores (e.g., SR) that allows recovery of Ca2+ from the extracellular space during repetitive muscle activity. We have recently shown that exercise triggers the formation of unique intracellular junctions between SR and transverse tubules named Ca 2+ entry units (CEUs). CEUs promote colocalization of STIM1 with ORAI1 and improve muscle function in presence of external Ca2+. TAs virtually identical to those of TAM patients are also found in fast-twitch fibers of aging male mice. Here, we used a combination of electron and confocal microscopy, Western blotting, and ex vivo stimulation protocols (in presence or absence of external Ca2+) to evaluate the presence of TAs, STIM1-ORAI1 localization and expression and fatigue resistance of intact extensor digitorum longus (EDL) muscles in wild-type male adult (4-month-old) and aged (24-month-old) mice and in mice trained in wheel cages for 15 months (from 9 to 24 months of age). The results collected indicate that (i) aging causes STIM1 and ORAI1 to accumulate in TAs and (ii) long-term exercise significantly reduced formation of TAs. In addition, (iii) EDL muscles from aged mice exhibited a faster decay of contractile force than adult muscles, likely caused by their inability to refill intracellular Ca2+ stores, and (iv) exercise in wheel cages restored the capability of aged EDL muscles to use external Ca2+ by promoting maintenance of CEUs. In conclusion, exercise prevented improper accumulation of STIM1 and ORAI1 in TAs during aging, maintaining the capability of aged muscle to refill intracellular Ca2+ stores via SOCE.
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Affiliation(s)
- Simona Boncompagni
- Center for Advanced Studies and Technology (CAST), University G. d’Annunzio (Ud’A) of Chieti-Pescara, Chieti, Italy
- Department of Neuroscience, Imaging and Clinical Sciences (DNICS), University G. d’Annunzio (Ud’A) of Chieti-Pescara, Chieti, Italy
| | - Claudia Pecorai
- Center for Advanced Studies and Technology (CAST), University G. d’Annunzio (Ud’A) of Chieti-Pescara, Chieti, Italy
- Department of Medicine and Aging Sciences (DMSI), University G. d’Annunzio (Ud’A) of Chieti-Pescara, Chieti, Italy
| | - Antonio Michelucci
- Center for Advanced Studies and Technology (CAST), University G. d’Annunzio (Ud’A) of Chieti-Pescara, Chieti, Italy
- Department of Medicine and Aging Sciences (DMSI), University G. d’Annunzio (Ud’A) of Chieti-Pescara, Chieti, Italy
| | - Laura Pietrangelo
- Center for Advanced Studies and Technology (CAST), University G. d’Annunzio (Ud’A) of Chieti-Pescara, Chieti, Italy
- Department of Medicine and Aging Sciences (DMSI), University G. d’Annunzio (Ud’A) of Chieti-Pescara, Chieti, Italy
| | - Feliciano Protasi
- Center for Advanced Studies and Technology (CAST), University G. d’Annunzio (Ud’A) of Chieti-Pescara, Chieti, Italy
- Department of Medicine and Aging Sciences (DMSI), University G. d’Annunzio (Ud’A) of Chieti-Pescara, Chieti, Italy
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9
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Protasi F, Pietrangelo L, Boncompagni S. Calcium entry units (CEUs): perspectives in skeletal muscle function and disease. J Muscle Res Cell Motil 2020; 42:233-249. [PMID: 32812118 PMCID: PMC8332569 DOI: 10.1007/s10974-020-09586-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 08/03/2020] [Indexed: 12/28/2022]
Abstract
In the last decades the term Store-operated Ca2+ entry (SOCE) has been used in the scientific literature to describe an ubiquitous cellular mechanism that allows recovery of calcium (Ca2+) from the extracellular space. SOCE is triggered by a reduction of Ca2+ content (i.e. depletion) in intracellular stores, i.e. endoplasmic or sarcoplasmic reticulum (ER and SR). In skeletal muscle the mechanism is primarily mediated by a physical interaction between stromal interaction molecule-1 (STIM1), a Ca2+ sensor located in the SR membrane, and ORAI1, a Ca2+-permeable channel of external membranes, located in transverse tubules (TTs), the invaginations of the plasma membrane (PM) deputed to propagation of action potentials. It is generally accepted that in skeletal muscle SOCE is important to limit muscle fatigue during repetitive stimulation. We recently discovered that exercise promotes the assembly of new intracellular junctions that contains colocalized STIM1 and ORAI1, and that the presence of these new junctions increases Ca2+ entry via ORAI1, while improving fatigue resistance during repetitive stimulation. Based on these findings we named these new junctions Ca2+ Entry Units (CEUs). CEUs are dynamic organelles that assemble during muscle activity and disassemble during recovery thanks to the plasticity of the SR (containing STIM1) and the elongation/retraction of TTs (bearing ORAI1). Interestingly, similar structures described as SR stacks were previously reported in different mouse models carrying mutations in proteins involved in Ca2+ handling (calsequestrin-null mice; triadin and junctin null mice, etc.) or associated to microtubules (MAP6 knockout mice). Mutations in Stim1 and Orai1 (and calsequestrin-1) genes have been associated to tubular aggregate myopathy (TAM), a muscular disease characterized by: (a) muscle pain, cramping, or weakness that begins in childhood and worsens over time, and (b) the presence of large accumulations of ordered SR tubes (tubular aggregates, TAs) that do not contain myofibrils, mitochondria, nor TTs. Interestingly, TAs are also present in fast twitch muscle fibers of ageing mice. Several important issues remain un-answered: (a) the molecular mechanisms and signals that trigger the remodeling of membranes and the functional activation of SOCE during exercise are unclear; and (b) how dysfunctional SOCE and/or mutations in Stim1, Orai1 and calsequestrin (Casq1) genes lead to the formation of tubular aggregates (TAs) in aging and disease deserve investigation.
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Affiliation(s)
- Feliciano Protasi
- CAST, Center for Advanced Studies and Technology, University G. d'Annunzio of Chieti-Pescara, 66100, Chieti, Italy.
- DMSI, Department of Medicine and Aging Sciences, University G. d'Annunzio of Chieti-Pescara, 66100, Chieti, Italy.
| | - Laura Pietrangelo
- CAST, Center for Advanced Studies and Technology, University G. d'Annunzio of Chieti-Pescara, 66100, Chieti, Italy
- DMSI, Department of Medicine and Aging Sciences, University G. d'Annunzio of Chieti-Pescara, 66100, Chieti, Italy
| | - Simona Boncompagni
- CAST, Center for Advanced Studies and Technology, University G. d'Annunzio of Chieti-Pescara, 66100, Chieti, Italy
- DNICS, Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio of Chieti-Pescara, 66100, Chieti, Italy
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10
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Kim H, Kim MC, Asada HH. Extracellular matrix remodelling induced by alternating electrical and mechanical stimulations increases the contraction of engineered skeletal muscle tissues. Sci Rep 2019; 9:2732. [PMID: 30804393 PMCID: PMC6389954 DOI: 10.1038/s41598-019-39522-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 01/28/2019] [Indexed: 12/22/2022] Open
Abstract
Engineered skeletal muscles are inferior to natural muscles in terms of contractile force, hampering their potential use in practical applications. One major limitation is that the extracellular matrix (ECM) not only impedes the contraction but also ineffectively transmits the forces generated by myotubes to the load. In the present study, ECM remodelling improves contractile force in a short time, and a coordinated, combined electrical and mechanical stimulation induces the desired ECM remodelling. Notably, the application of single and combined stimulations to the engineered muscles remodels the structure of their ECM networks, which determines the mechanical properties of the ECM. Myotubes in the tissues are connected in parallel and in series to the ECM. The stiffness of the parallel ECM must be low not to impede contraction, while the stiffness of the serial ECM must be high to transmit the forces to the load. Both the experimental results and the mechanistic model suggest that the combined stimulation through coordination reorients the ECM fibres in such a way that the parallel ECM stiffness is reduced, while the serial ECM stiffness is increased. In particular, 3 and 20 minutes of alternating electrical and mechanical stimulations increase the force by 18% and 31%, respectively.
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Affiliation(s)
- Hyeonyu Kim
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - Min-Cheol Kim
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - H Harry Asada
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- BioSystem and Micromechanics IRG, Singapore-MIT Alliance for Research and Technology, National University of Singapore, Singapore, 117543, Singapore
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11
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Abstract
Ca(2+) release from intracellular stores and influx from extracellular reservoir regulate a wide range of physiological functions including muscle contraction and rhythmic heartbeat. One of the most ubiquitous pathways involved in controlled Ca(2+) influx into cells is store-operated Ca(2+) entry (SOCE), which is activated by the reduction of Ca(2+) concentration in the lumen of endoplasmic or sarcoplasmic reticulum (ER/SR). Although SOCE is pronounced in non-excitable cells, accumulating evidences highlight its presence and important roles in skeletal muscle and heart. Recent discovery of STIM proteins as ER/SR Ca(2+) sensors and Orai proteins as Ca(2+) channel pore forming unit expedited the mechanistic understanding of this pathway. This review focuses on current advances of SOCE components, regulation and physiologic and pathophysiologic roles in muscles. The specific property and the dysfunction of this pathway in muscle diseases, and new directions for future research in this rapidly growing field are discussed.
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Affiliation(s)
- Zui Pan
- Department of Internal Medicine-Cardiovascular Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Marco Brotto
- Muscle Biology Research Group-MUBIG, Schools of Nursing & Medicine, University of Missouri-Kansas City, MO, USA
| | - Jianjie Ma
- Department of Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
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12
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Zhou X, Lin P, Yamazaki D, Park KH, Komazaki S, Chen SRW, Takeshima H, Ma J. Trimeric intracellular cation channels and sarcoplasmic/endoplasmic reticulum calcium homeostasis. Circ Res 2014; 114:706-16. [PMID: 24526676 DOI: 10.1161/circresaha.114.301816] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Trimeric intracellular cation channels (TRIC) represents a novel class of trimeric intracellular cation channels. Two TRIC isoforms have been identified in both the human and the mouse genomes: TRIC-A, a subtype predominantly expressed in the sarcoplasmic reticulum (SR) of muscle cells, and TRIC-B, a ubiquitous subtype expressed in the endoplasmic reticulum (ER) of all tissues. Genetic ablation of either TRIC-A or TRIC-B leads to compromised K(+) permeation and Ca(2+) release across the SR/ER membrane, supporting the hypothesis that TRIC channels provide a counter balancing K(+) flux that reduces SR/ER membrane depolarization for maintenance of the electrochemical gradient that drives SR/ER Ca(2+) release. TRIC-A and TRIC-B seem to have differential functions in Ca(2+) signaling in excitable and nonexcitable cells. Tric-a(-/-) mice display defective Ca(2+) sparks and spontaneous transient outward currents in arterial smooth muscle and develop hypertension, in addition to skeletal muscle dysfunction. Knockout of TRIC-B results in abnormal IP3 receptor-mediated Ca(2+) release in airway epithelial cells, respiratory defects, and neonatal lethality. Double knockout mice lacking both TRIC-A and TRIC-B show embryonic lethality as a result of cardiac arrest. Such an aggravated lethality indicates that TRIC-A and TRIC-B share complementary physiological functions in Ca(2+) signaling in embryonic cardiomyocytes. Tric-a(-/-) and Tric-b(+/-) mice are viable and susceptible to stress-induced heart failure. Recent evidence suggests that TRIC-A directly modulates the function of the cardiac ryanodine receptor 2 Ca(2+) release channel, which in turn controls store-overload-induced Ca(2+) release from the SR. Thus, the TRIC channels, in addition to providing a countercurrent for SR/ER Ca(2+) release, may also function as accessory proteins that directly modulate the ryanodine receptor/IP3 receptor channel functions.
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Affiliation(s)
- Xinyu Zhou
- From the Department of Surgery, Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University, Columbus (X.Z., P.L., K.H.P., J.M.); Department of Biological Chemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Kyoto, Japan (D.Y., H.T.); Department of Anatomy, Saitama Medical University, Saitama, Japan (S.K.); and Departments of Physiology and Pharmacology, and Biochemistry and Molecular Biology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada (W.C.)
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13
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Protasi F, Paolini C, Canato M, Reggiani C, Quarta M. Lessons from calsequestrin-1 ablation in vivo: much more than a Ca(2+) buffer after all. J Muscle Res Cell Motil 2011; 32:257-70. [PMID: 22130610 DOI: 10.1007/s10974-011-9277-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 11/09/2011] [Indexed: 10/15/2022]
Abstract
Calsequestrin type-1 (CASQ1), the main sarcoplasmic reticulum (SR) Ca(2+) binding protein, plays a dual role in skeletal fibers: a) it provides a large pool of rapidly-releasable Ca(2+) during excitation-contraction (EC) coupling; and b) it modulates the activity of ryanodine receptors (RYRs), the SR Ca(2+) release channels. We have generated a mouse lacking CASQ1 in order to further characterize the role of CASQ1 in skeletal muscle. Contrary to initial expectations, CASQ1 ablation is compatible with normal motor activity, in spite of moderate muscle atrophy. However, CASQ1 deficiency results in profound remodeling of the EC coupling apparatus: shrinkage of junctional SR lumen; proliferation of SR/transverse-tubule contacts; and increased density of RYRs. While force development during a twitch is preserved, it is nevertheless characterized by a prolonged time course, likely reflecting impaired Ca(2+) re-uptake by the SR. Finally, lack of CASQ1 also results in increased rate of SR Ca(2+) depletion and inability of muscle to sustain tension during a prolonged tetani. All modifications are more pronounced (or only found) in fast-twitch extensor digitorum longus muscle compared to slow-twitch soleus muscle, likely because the latter expresses higher amounts of calsequestrin type-2 (CASQ2). Surprisingly, male CASQ1-null mice also exhibit a marked increased rate of spontaneous mortality suggestive of a stress-induced phenotype. Consistent with this idea, CASQ1-null mice exhibit an increased susceptibility to undergo a hypermetabolic syndrome characterized by whole body contractures, rhabdomyolysis, hyperthermia and sudden death in response to halothane- and heat-exposure, a phenotype remarkably similar to human malignant hyperthermia and environmental heat-stroke. The latter findings validate the CASQ1 gene as a candidate for linkage analysis in human muscle disorders.
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Affiliation(s)
- Feliciano Protasi
- CeSI-Center for Research on Ageing & DNI-Department of Neuroscience and Imaging, University Gabriele d’Annunzioof Chieti, Via Colle dell’Ara, 66100 Chieti, Italy.
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14
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Simkin D, Bendahhou S. Skeletal muscle na channel disorders. Front Pharmacol 2011; 2:63. [PMID: 22016737 PMCID: PMC3192954 DOI: 10.3389/fphar.2011.00063] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 09/28/2011] [Indexed: 11/13/2022] Open
Abstract
Five inherited human disorders affecting skeletal muscle contraction have been traced to mutations in the gene encoding the voltage-gated sodium channel Nav1.4. The main symptoms of these disorders are myotonia or periodic paralysis caused by changes in skeletal muscle fiber excitability. Symptoms of these disorders vary from mild or latent disease to incapacitating or even death in severe cases. As new human sodium channel mutations corresponding to disease states become discovered, the importance of understanding the role of the sodium channel in skeletal muscle function and disease state grows.
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Affiliation(s)
- Dina Simkin
- UMR 6097, CNRS, TIANP, University of Nice Sophia-Antipolis Nice, France
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15
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Both basic and acidic amino acid residues of IpTx(a) are involved in triggering substate of RyR1. J Biomed Biotechnol 2011; 2011:386384. [PMID: 22007141 PMCID: PMC3192407 DOI: 10.1155/2011/386384] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 08/05/2011] [Accepted: 08/10/2011] [Indexed: 12/02/2022] Open
Abstract
Imperatoxin A (IpTxa) is known to modify the gating of skeletal ryanodine receptor (RyR1). In this paper, the ability of charged aa residues of IpTxa to induce substate of native RyR1 in HSR was examined. Our results show that the basic residues (e.g., Lys19, Lys20, Lys22, Arg23, and Arg24) are important for producing substate of RyR1. In addition, other basic residues (e.g., Lys30, Arg31, and Arg33) near the C-terminus and some acidic residues (e.g., Glu29, Asp13, and Asp2) are also involved in the generation of substate. Residues such as Lys8 and Thr26 may be involved in the self-regulation of substate of RyR1, since alanine substitution of the aa residues led to a drastic conversion to the substate. The modifications of the channel gating by the wild-type and mutant toxins were similar in purified RyR1. Taken together, the specific charge distributions on the surface of IpTxa are essential for regulation of the channel gating of RyR1.
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16
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Differential effect of calsequestrin ablation on structure and function of fast and slow skeletal muscle fibers. J Biomed Biotechnol 2011; 2011:634075. [PMID: 21941434 PMCID: PMC3173739 DOI: 10.1155/2011/634075] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Accepted: 07/12/2011] [Indexed: 12/02/2022] Open
Abstract
We compared structure and function of EDL and Soleus muscles in adult (4–6 m) mice lacking both Calsequestrin (CASQ) isoforms, the main SR Ca2+-binding proteins. Lack of CASQ induced ultrastructural alterations in ~30% of Soleus fibers, but not in EDL. Twitch time parameters were prolonged in both muscles, although tension was not reduced. However, when stimulated for 2 sec at 100 hz, Soleus was able to sustain contraction, while in EDL active tension declined by 70–80%. The results presented in this paper unmask a differential effect of CASQ1&2 ablation in fast versus slow fibers. CASQ is essential in EDL to provide large amount of Ca2+ released from the SR during tetanic stimulation. In contrast, Soleus deals much better with lack of CASQ because slow fibers require lower Ca2+ amounts and slower cycling to function properly. Nevertheless, Soleus suffers more severe structural damage, possibly because SR Ca2+ leak is more pronounced.
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17
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Capes EM, Loaiza R, Valdivia HH. Ryanodine receptors. Skelet Muscle 2011; 1:18. [PMID: 21798098 PMCID: PMC3156641 DOI: 10.1186/2044-5040-1-18] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 05/04/2011] [Indexed: 12/31/2022] Open
Abstract
Excitation-contraction coupling involves the faithful conversion of electrical stimuli to mechanical shortening in striated muscle cells, enabled by the ubiquitous second messenger, calcium. Crucial to this process are ryanodine receptors (RyRs), the sentinels of massive intracellular calcium stores contained within the sarcoplasmic reticulum. In response to sarcolemmal depolarization, RyRs release calcium into the cytosol, facilitating mobilization of the myofilaments and enabling cell contraction. In order for the cells to relax, calcium must be rapidly resequestered or extruded from the cytosol. The sustainability of this cycle is crucially dependent upon precise regulation of RyRs by numerous cytosolic metabolites and by proteins within the lumen of the sarcoplasmic reticulum and those directly associated with the receptors in a macromolecular complex. In addition to providing the majority of the calcium necessary for contraction of cardiac and skeletal muscle, RyRs act as molecular switchboards that integrate a multitude of cytosolic signals such as dynamic and steady calcium fluctuations, β-adrenergic stimulation (phosphorylation), nitrosylation and metabolic states, and transduce these signals to the channel pore to release appropriate amounts of calcium. Indeed, dysregulation of calcium release via RyRs is associated with life-threatening diseases in both skeletal and cardiac muscle. In this paper, we briefly review some of the most outstanding structural and functional attributes of RyRs and their mechanism of regulation. Further, we address pathogenic RyR dysfunction implicated in cardiovascular disease and skeletal myopathies.
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Affiliation(s)
- E Michelle Capes
- Department of Cellular and Regenerative Biology, University of Wisconsin Medical School, Madison, WI 53711, USA.
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18
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Silverio ALF, Saier MH. Bioinformatic characterization of the trimeric intracellular cation-specific channel protein family. J Membr Biol 2011; 241:77-101. [PMID: 21519847 DOI: 10.1007/s00232-011-9364-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 03/26/2011] [Indexed: 12/29/2022]
Abstract
Trimeric intracellular cation-specific (TRIC) channels are integral to muscle excitation-contraction coupling. TRIC channels provide counter-ionic flux when calcium is rapidly transported from intracellular stores to the cell cytoplasm. Until recently, knowledge of the presence of these proteins was limited to animals. We analyzed the TRIC family and identified a profusion of prokaryotic family members with topologies and motifs similar to those of their eukaryotic counterparts. Prokaryotic members far outnumber eukaryotic members, and although none has been functionally characterized, the evidence suggests that they function as secondary carriers. The presence of fused N- or C-terminal domains of known biochemical functions as well as genomic context analyses provide clues about the functions of these prokaryotic homologs. They are proposed to function in metabolite (e.g., amino acid/nucleotide) efflux. Phylogenetic analysis revealed that TRIC channel homologs diverged relatively early during evolutionary history and that horizontal gene transfer was frequent in prokaryotes but not in eukaryotes. Topological analyses of TRIC channels revealed that these proteins possess seven putative transmembrane segments (TMSs), which arose by intragenic duplication of a three-TMS polypeptide-encoding genetic element followed by addition of a seventh TMS at the C terminus to give the precursor of all current TRIC family homologs. We propose that this family arose in prokaryotes.
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Affiliation(s)
- Abe L F Silverio
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA
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19
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Sarcoplasmic reticulum: structural determinants and protein dynamics. Int J Biochem Cell Biol 2011; 43:1075-8. [PMID: 21515402 DOI: 10.1016/j.biocel.2011.04.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Revised: 03/21/2011] [Accepted: 04/08/2011] [Indexed: 11/21/2022]
Abstract
The sarcoplasmic reticulum is a unique organelle found in muscle cells that is dedicated to the regulation of Ca(2+) homeostasis and activation of myofilament contraction. The functional requirement for an efficient and synchronous activation of Ca(2+) release from the SR, following the depolarization of the plasma membrane, accounts for the complex three-dimensional organization of internal membranes observed in muscle cells and for the localization of proteins at specific sites of the SR. Recent advancements in understanding the molecular basis of SR structure and function have greatly increased our understanding of muscle cellular physiology and biology. Parallel work has revealed that several human diseases affecting skeletal and cardiac tissues are linked to either mutations or altered post-translational modifications of SR proteins.
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20
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21
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Zhao X, Yamazaki D, Park KH, Komazaki S, Tjondrokoesoemo A, Nishi M, Lin P, Hirata Y, Brotto M, Takeshima H, Ma J. Ca2+ overload and sarcoplasmic reticulum instability in tric-a null skeletal muscle. J Biol Chem 2010; 285:37370-6. [PMID: 20858894 DOI: 10.1074/jbc.m110.170084] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The sarcoplasmic reticulum (SR) of skeletal muscle contains K(+), Cl(-), and H(+) channels may facilitate charge neutralization during Ca(2+) release. Our recent studies have identified trimeric intracellular cation (TRIC) channels on SR as an essential counter-ion permeability pathway associated with rapid Ca(2+) release from intracellular stores. Skeletal muscle contains TRIC-A and TRIC-B isoforms as predominant and minor components, respectively. Here we test the physiological function of TRIC-A in skeletal muscle. Biochemical assay revealed abundant expression of TRIC-A relative to the skeletal muscle ryanodine receptor with a molar ratio of TRIC-A/ryanodine receptor ∼5:1. Electron microscopy with the tric-a(-/-) skeletal muscle showed Ca(2+) overload inside the SR with frequent formation of Ca(2+) deposits compared with the wild type muscle. This elevated SR Ca(2+) pool in the tric-a(-/-) muscle could be released by caffeine, whereas the elemental Ca(2+) release events, e.g. osmotic stress-induced Ca(2+) spark activities, were significantly reduced likely reflecting compromised counter-ion movement across the SR. Ex vivo physiological test identified the appearance of "alternan" behavior with isolated tric-a(-/-) skeletal muscle, i.e. transient and drastic increase in contractile force appeared within the decreasing force profile during repetitive fatigue stimulation. Inhibition of SR/endoplasmic reticulum Ca(2+ ATPase) function could lead to aggravation of the stress-induced alternans in the tric-a(-/-) muscle. Our data suggests that absence of TRIC-A may lead to Ca(2+) overload in SR, which in combination with the reduced counter-ion movement may lead to instability of Ca(2+) movement across the SR membrane. The observed alternan behavior with the tric-a(-/-) muscle may reflect a skeletal muscle version of store overload-induced Ca(2+) release that has been reported in the cardiac muscle under stress conditions.
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Affiliation(s)
- Xiaoli Zhao
- Department of Physiology and Biophysics, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
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22
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Assembly and dynamics of proteins of the longitudinal and junctional sarcoplasmic reticulum in skeletal muscle cells. Proc Natl Acad Sci U S A 2009; 106:4695-700. [PMID: 19261851 DOI: 10.1073/pnas.0810243106] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The sarcoplasmic reticulum (SR) of skeletal muscle cells is a complex network of tubules and cisternae that share a common lumen delimited by a single continuous membrane. The SR contains longitudinal and junctional domains characterized by distinctive patterns of protein localization, but how SR proteins reach and/or are retained at these sites is not known. Here, we report that the organization of longitudinal SR proteins is a slow process characterized by temporally distinct patterns of protein localization. In contrast, junctional SR proteins rapidly and synchronously assembled into clusters which, however, merged into mature triadic junctions only after completion of longitudinal SR protein organization. Fluorescence recovery after photobleaching experiments indicated that SR organization was accompanied by significant changes in the dynamic properties of longitudinal and junctional proteins. The decrease in mobility that accompanied organization of the longitudinal SR proteins ank1.5-GFP and GFP-InsP3R1 was abrogated by deletion of specific binding sites for myofibrillar or cytoskeletal proteins, respectively. Assembly of junctional SR domains was accompanied by a strong decrease in mobility of junctional proteins that in triadin appeared to be mediated by its intraluminal region. Together, the data suggest that the organization of specific SR domains results from a process of membrane reorganization accompanied by the establishment of multiple protein-protein interactions with intrinsic and extrinsic cues.
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23
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Rigoard P, Buffenoir K, Wager M, Bauche S, Giot JP, Lapierre F. [Molecular architecture of the sarcoplasmic reticulum and its role in the ECC]. Neurochirurgie 2009; 55 Suppl 1:S83-91. [PMID: 19233437 DOI: 10.1016/j.neuchi.2008.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Accepted: 05/09/2008] [Indexed: 11/16/2022]
Abstract
The sarcoplasmic reticulum (SR) plays a fundamental role in excitation-contraction coupling, which propagates the electric signal conversion along the muscle fiber's plasmic membrane to a mechanical event manifested as a muscle contraction. It plays a crucial role in calcium homeostasis and intracellular calcium storage control (storage, liberation and uptake) necessary for fiber muscle contraction and then relaxation. These functions take place at the triad, made up of individualized SR subdomains where the protein-specific organization provides efficient and fast coupling. Ryanodine receptors (RyR) and dihydropyridine receptors (DHPR) mainly act in calcium exchanges in the SR. This particular structural and molecular architecture must be correlated to its functional specificity.
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Affiliation(s)
- P Rigoard
- Service de neurochirurgie, CHU La Milétrie, 2, rue de la Milétrie, BP 577, 86021 Poitiers cedex, France.
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24
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Dainese M, Quarta M, Lyfenko AD, Paolini C, Canato M, Reggiani C, Dirksen RT, Protasi F. Anesthetic- and heat-induced sudden death in calsequestrin-1-knockout mice. FASEB J 2009; 23:1710-20. [PMID: 19237502 DOI: 10.1096/fj.08-121335] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Calsequestrin-1 (CASQ1) is a moderate-affinity, high-capacity Ca(2+)-binding protein in the sarcoplasmic reticulum (SR) terminal cisternae of skeletal muscle. CASQ1 functions as both a Ca(2+)-binding protein and a luminal regulator of ryanodine receptor (RYR1)-mediated Ca(2+) release. Mice lacking skeletal CASQ1 are viable but exhibit reduced levels of releasable Ca(2+) and altered contractile properties. Here we report that CASQ1-null mice exhibit increased spontaneous mortality and susceptibility to heat- and anesthetic-induced sudden death. Exposure of CASQ1-null mice to either 2% halothane or heat stress triggers lethal episodes characterized by whole-body contractures, elevated core temperature, and severe rhabdomyolysis, which are prevented by prior dantrolene administration. The characteristics of these events are remarkably similar to analogous episodes observed in humans with malignant hyperthermia (MH) and animal models of MH and environmental heat stroke (EHS). In vitro studies indicate that CASQ1-null muscle exhibits increased contractile sensitivity to temperature and caffeine, temperature-dependent increases in resting Ca(2+), and an increase in the magnitude of depolarization-induced Ca(2+) release. These results demonstrate that CASQ1 deficiency alters proper control of RYR1 function and suggest CASQ1 as a potential candidate gene for linkage analysis in families with MH/EHS where mutations in the RYR1 gene are excluded.
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Affiliation(s)
- Marco Dainese
- Ce.S.I.-Department of Basic and Applied Medical Sciences, Interuniversity Institute of Myology, University G. d'Annunzio, I-66013 Chieti, Italy
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25
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Weisleder N, Ma J. Altered Ca2+ sparks in aging skeletal and cardiac muscle. Ageing Res Rev 2008; 7:177-88. [PMID: 18272434 DOI: 10.1016/j.arr.2007.12.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Revised: 12/17/2007] [Accepted: 12/18/2007] [Indexed: 11/26/2022]
Abstract
Ca2+ sparks are the fundamental units that comprise Ca2+-induced Ca2+ release (CICR) in striated muscle cells. In cardiac muscle, spontaneous Ca2+ sparks underlie the rhythmic CICR activity during heart contraction. In skeletal muscle, Ca2+ sparks remain quiescent during the resting state and are activated in a plastic fashion to accommodate various levels of stress. With aging, the plastic Ca2+ spark signal becomes static in skeletal muscle, whereas loss of CICR control leads to leaky Ca2+ spark activity in aged cardiomyocytes. Ca2+ spark responses reflect the integrated function of the intracellular Ca2+ regulatory machinery centered around the triad or dyad junctional complexes of striated muscles, which harbor the principal molecular players of excitation-contraction coupling. This review highlights the contribution of age-related modification of the Ca2+ release machinery and the effect of membrane structure and membrane cross-talk on the altered Ca2+ spark signaling during aging of striated muscles.
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26
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Divet A, Paesante S, Grasso C, Cavagna D, Tiveron C, Paolini C, Protasi F, Huchet-Cadiou C, Treves S, Zorzato F. Increased Ca2+ storage capacity of the skeletal muscle sarcoplasmic reticulum of transgenic mice over-expressing membrane bound calcium binding protein junctate. J Cell Physiol 2008; 213:464-74. [PMID: 17516551 DOI: 10.1002/jcp.21121] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Junctate is an integral sarco(endo)plasmic reticulum protein expressed in many tissues including heart and skeletal muscle. Because of its localization and biochemical characteristics, junctate is deemed to participate in the regulation of the intracellular Ca2+ concentration. However, its physiological function in muscle cells has not been investigated yet. In this study we examined the effects of junctate over-expression by generating a transgenic mouse model which over-expresses junctate in skeletal muscle. Our results demonstrate that junctate over-expression induced a significant increase in SR Ca2+ storage capacity which was paralleled by an increased 4-chloro-m-cresol and caffeine-induced Ca2+ release, whereas it did not affect SR Ca2+-dependent ATPase activity and SR Ca2+ loading rates. In addition, junctate over-expression did not affect the expression levels of SR Ca2+ binding proteins such as calsequestrin, calreticulin and sarcalumenin. These findings suggest that junctate over-expression is associated with an increase in the SR Ca2+ storage capacity and releasable Ca2+ content and support a physiological role for junctate in intracellular Ca2+ homeostasis.
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Affiliation(s)
- Alexandra Divet
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, University of Ferrara, Ferrara, Italy
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Weisleder N, Takeshima H, Ma J. Immuno-proteomic approach to excitation--contraction coupling in skeletal and cardiac muscle: molecular insights revealed by the mitsugumins. Cell Calcium 2008; 43:1-8. [PMID: 18061662 PMCID: PMC3059838 DOI: 10.1016/j.ceca.2007.10.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2007] [Revised: 10/17/2007] [Accepted: 10/19/2007] [Indexed: 12/20/2022]
Abstract
A comprehensive understanding of excitation-contraction (E-C) coupling in skeletal and cardiac muscle requires that all the major components of the Ca(2+) release machinery be resolved. We utilized a unique immuno-proteomic approach to generate a monoclonal antibody library that targets proteins localized to the skeletal muscle triad junction, which provides a structural context to allow efficient E-C coupling. Screening of this library has identified several mitsugumins (MG); proteins that can be localized to the triad junction in mammalian skeletal muscle. Many of these proteins, including MG29 and junctophilin, are important components in maintaining the structural integrity of the triad junction. Other triad proteins, such as calumin, play a more direct role in regulation of muscle Ca(2+) homeostasis. We have recently identified a family of trimeric intracellular cation-selective (TRIC) channels that allow for K(+) movement into the endoplasmic or sarcoplasmic reticulum to counter a portion of the transient negative charge produced by Ca(2+) release into the cytosol. Further study of TRIC channel function and other novel mitsugumins will increase our understanding of E-C coupling and Ca(2+) homoeostasis in muscle physiology and pathophysiology.
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Affiliation(s)
- Noah Weisleder
- Department of Physiology and Biophysics, UMDNJ-Robert Wood Johnson Medical School, NJ 08854, USA
| | - Hiroshi Takeshima
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Jianjie Ma
- Department of Physiology and Biophysics, UMDNJ-Robert Wood Johnson Medical School, NJ 08854, USA
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Martins AS, Shkryl VM, Nowycky MC, Shirokova N. Reactive oxygen species contribute to Ca2+ signals produced by osmotic stress in mouse skeletal muscle fibres. J Physiol 2007; 586:197-210. [PMID: 17974587 DOI: 10.1113/jphysiol.2007.146571] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Ca(2+) sparks, localized elevations in cytosolic [Ca(2+)], are rarely detected in intact adult mammalian skeletal muscle under physiological conditions. However, they have been observed in permeabilized cells and in intact fibres subjected to stresses, such as osmotic shock and strenuous exercise. Our previous studies indicated that an excess in cellular reactive oxygen species (ROS) generation over the ROS scavenging capabilities could be one of the up-stream causes of Ca(2+) spark appearance in permeabilized muscle fibres. Here we tested whether the cytosolic ROS balance is compromised in intact skeletal muscle fibres that underwent osmotic shock and whether this misbalance contributes to unmasking Ca(2+) sparks. Spontaneous Ca(2+) sparks and the rate of ROS generation were assessed with single photon confocal microscopy and fluorescent indicators fluo-4, CM-H(2)DCFDA and MitoSOX Red. Osmotic shock produced spontaneous Ca(2+) sparks and a concomitant significant increase in ROS production. Preincubation of muscle cells with ROS scavengers (e.g. MnTBAP, Mn-cpx 3, TIRON) nearly eliminated Ca(2+) sparks. In addition, inhibitors of NAD(P)H oxidase (DPI and apocynin) significantly reduced ROS production and suppressed the appearance of Ca(2+) sparks. Taken together, the data suggest that ROS contribute to the abnormal Ca(2+) spark activity in mammalian skeletal muscle subjected to osmotic stress and also indicate that NAD(P)H oxidase is a possible source of ROS. We propose that ROS-dependent Ca(2+) sparks are an important component of adaptive/maladaptive muscle responses under various pathological conditions such as eccentric stretch, osmotic changes during ischaemia and reperfusion, and some muscle diseases.
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Affiliation(s)
- Adriano S Martins
- Department of Pharmacology and Physiology, UMDNJ, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA
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29
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Paolini C, Quarta M, Nori A, Boncompagni S, Canato M, Volpe P, Allen PD, Reggiani C, Protasi F. Reorganized stores and impaired calcium handling in skeletal muscle of mice lacking calsequestrin-1. J Physiol 2007; 583:767-84. [PMID: 17627988 PMCID: PMC2277031 DOI: 10.1113/jphysiol.2007.138024] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Calsequestrin (CS), the major Ca(2+)-binding protein in the sarcoplasmic reticulum (SR), is thought to play a dual role in excitation-contraction coupling: buffering free Ca(2+) increasing SR capacity, and modulating the activity of the Ca(2+) release channels (RyRs). In this study, we generated and characterized the first murine model lacking the skeletal CS isoform (CS1). CS1-null mice are viable and fertile, even though skeletal muscles appear slightly atrophic compared to the control mice. No compensatory increase of the cardiac isoform CS2 is detectable in any type of skeletal muscle. CS1-null muscle fibres are characterized by structural and functional changes, which are much more evident in fast-twitch muscles (EDL) in which most fibres express only CS1, than in slow-twitch muscles (soleus), where CS2 is expressed in about 50% of the fibres. In isolated EDL muscle, force development is preserved, but characterized by prolonged time-to-peak and half-relaxation time, probably related to impaired calcium release from and re-uptake by the SR. Ca(2+)-imaging studies show that the amount of Ca(2+) released from the SR and the amplitude of the Ca(2+) transient are significantly reduced. The lack of CS1 also causes significant ultrastructural changes, which include: (i) striking proliferation of SR junctional domains; (ii) increased density of Ca(2+)-release channels (confirmed also by (3)H-ryanodine binding); (iii) decreased SR terminal cisternae volume; (iv) higher density of mitochondria. Taken together these results demonstrate that CS1 is essential for the normal development of the SR and its calcium release units and for the storage and release of appropriate amounts of SR Ca(2+).
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Affiliation(s)
- Cecilia Paolini
- IIM Interuniversity Institute of Myology, Ce.S.I. Centro Science dell'Invecchiamento, University G. d' Annunzio, I-66013 Chieti, Italy
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Boncompagni S, d'Amelio L, Fulle S, Fanò G, Protasi F. Progressive disorganization of the excitation-contraction coupling apparatus in aging human skeletal muscle as revealed by electron microscopy: a possible role in the decline of muscle performance. J Gerontol A Biol Sci Med Sci 2006; 61:995-1008. [PMID: 17077192 DOI: 10.1093/gerona/61.10.995] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
An impairment of the mechanisms controlling the release of calcium from internal stores (excitation-contraction [EC] coupling) has been proposed to contribute to the age-related decline of muscle performance that accompanies aging (EC uncoupling theory). EC coupling in muscle fibers occurs at the junctions between sarcoplasmic reticulum and transverse tubules, in structures called calcium release units (CRUs). We studied the frequency, cellular localization, and ultrastructure of CRUs in human muscle biopsies from male and female participants with ages ranging from 28 to 83 years. Our results show significant alterations in the CRUs' morphology and cellular disposition, and a significant decrease in their frequency between control and aged samples: 24.4/100 microm(2) (n = 2) versus 11.6/100 microm(2) (n = 7). These data indicate that in aging humans the EC coupling apparatus undergoes a partial disarrangement and a spatial reorganization that could interfere with an efficient delivery of Ca(2+) ions to the contractile proteins.
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Affiliation(s)
- Simona Boncompagni
- CeSI, Centro Scienze dell'Invecchiamento, Università degli Studi G. d'Annunzio, Chieti, CH I-66013, Italy
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Weisleder N, Ma JJ. Ca2+ sparks as a plastic signal for skeletal muscle health, aging, and dystrophy. Acta Pharmacol Sin 2006; 27:791-8. [PMID: 16787561 DOI: 10.1111/j.1745-7254.2006.00384.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Ca2+ sparks are the elementary units of intracellular Ca2+ signaling in striated muscle cells revealed as localized Ca2+ release events from sarcoplasmic reticulum (SR) by confocal microscopy. While Ca2+ sparks are well defined in cardiac muscle, there has been a general belief that these localized Ca2+ release events are rare in intact adult mammalian skeletal muscle. Several laboratories determined that Ca2+ sparks in mammalian skeletal muscle could only be observed in large numbers when the sarcolemmal membranes are permeabilized or the SR Ca2+ content is artificially manipulated, thus the cellular and molecular mechanisms underlying the regulation of Ca2+ sparks in skeletal muscle remain largely unexplored. Recently, we discovered that membrane deformation generated by osmotic stress induced a robust Ca2+ spark response confined in close spatial proximity to the sarcolemmal membrane in intact mouse muscle fibers. In addition to Ca2+ sparks, prolonged Ca2+ transients, termed Ca2+ bursts, are also identified in intact skeletal muscle. These induced Ca2+ release events are reversible and repeatable, revealing a plastic nature in young muscle fibers. In contrast, induced Ca2+ sparks in aged muscle are transient and cannot be re-stimulated. Dystrophic muscle fibers display uncontrolled Ca2+ sparks, where osmotic stress-induced Ca2+ sparks are not reversible and they are no longer spatially restricted to the sarcolemmal membrane. An understanding of the mechanisms that underlie generation of osmotic stress-induced Ca2+ sparks in skeletal muscle, and how these mechanisms are altered in pathology, will contribute to our understanding of the regulation of Ca2+ homeostasis in muscle physiology and pathophysiology.
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Affiliation(s)
- Noah Weisleder
- Department of Physiology and Biophysics, UMDNJ-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA
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32
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Balghi H, Sebille S, Constantin B, Patri S, Thoreau V, Mondin L, Mok E, Kitzis A, Raymond G, Cognard C. Mini-dystrophin expression down-regulates overactivation of G protein-mediated IP3 signaling pathway in dystrophin-deficient muscle cells. ACTA ACUST UNITED AC 2006; 127:171-82. [PMID: 16446505 PMCID: PMC2151485 DOI: 10.1085/jgp.200509456] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present here evidence for the enhancement of an inositol 1,4,5-trisphosphate (IP3) mediated calcium signaling pathway in myotubes from dystrophin-deficient cell lines (SolC1(−)) as compared to a cell line from the same origin but transfected with mini-dystrophin (SolD(+)). With confocal microscopy, we demonstrated that calcium rise, induced by the perifusion of a solution containing a high potassium concentration, was higher in SolC1(−) than in SolD(+) myotubes. The analysis of amplitude and kinetics of the calcium increase in SolC1(−) and in SolD(+) myotubes during the exposure with SR Ca2+ channel inhibitors (ryanodine and 2-APB) suggested the presence of two mechanisms of SR calcium release: (1) a fast SR calcium release that depended on ryanodine receptors and (2) a slow SR calcium release mediated by IP3 receptors. Detection analyses of mRNAs (reverse transcriptase [RT]-PCR) and proteins (Western blot and immunolocalization) demonstrated the presence of the three known isoforms of IP3 receptors in both SolC1(−) and SolD(+) myotubes. Furthermore, analysis of the kinetics of the rise in calcium revealed that the slow IP3-dependent release may be increased in the SolC1(−) as compared to the SolD(+), suggesting an inhibitory effect of mini-dystrophin in this signaling pathway. Upon incubation with pertussis toxin (PTX), an inhibitory effect similar to that of the IP3R inhibitor (2-APB) was observed on K+-evoked calcium release. This result suggests the involvement of a Gi protein upstream of the IP3 pathway in these stimulation conditions. A hypothetical model is depicted in which both Gi protein and IP3 production could be involved in K+-evoked calcium release as well as a possible interaction with mini-dystrophin. Our findings demonstrate the existence of a potential relationship between mini-dystrophin and SR calcium release as well as a regulatory role of mini-dystrophin on intracellular signaling.
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MESH Headings
- Animals
- Blotting, Western
- Calcium/metabolism
- Calcium Channels/analysis
- Calcium Channels/chemistry
- Calcium Channels/drug effects
- Calcium Channels/genetics
- Calcium Channels/metabolism
- Calcium Channels/physiology
- Calcium Signaling
- Cell Line
- Down-Regulation
- Dystrophin/analysis
- Dystrophin/deficiency
- Dystrophin/genetics
- Dystrophin/physiology
- GTP-Binding Protein alpha Subunits, Gi-Go/physiology
- GTP-Binding Proteins/physiology
- Gene Expression
- Inositol 1,4,5-Trisphosphate/metabolism
- Inositol 1,4,5-Trisphosphate Receptors
- Mice
- Mice, Inbred C3H
- Microscopy, Confocal
- Muscle Fibers, Skeletal/metabolism
- Pertussis Toxin/pharmacology
- Potassium/pharmacology
- RNA, Messenger/analysis
- Receptors, Cytoplasmic and Nuclear/chemistry
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Ryanodine Receptor Calcium Release Channel/physiology
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Affiliation(s)
- Haouaria Balghi
- Institut de Physiologie et Biologie Cellulaires, CNRS UMR 6187, Université de Poitiers, France
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Divet A, Paesante S, Bleunven C, Anderson A, Treves S, Zorzato F. Novel sarco(endo)plasmic reticulum proteins and calcium homeostasis in striated muscles. J Muscle Res Cell Motil 2005; 26:7-12. [PMID: 16096683 DOI: 10.1007/s10974-005-9001-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2005] [Revised: 06/09/2005] [Accepted: 06/17/2005] [Indexed: 10/25/2022]
Abstract
The impact of calcium signaling on many cellular functions is reflected by the tight regulation of the intracellular Ca(2+) concentration that is ensured by diverse pumps, channels, transporters and Ca(2+) binding proteins. In this review, we present recently identified novel sarco(endo)plasmic reticulum proteins that may have a potential involvement in the regulation of Ca(2+) homeostasis in striated muscles.
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Affiliation(s)
- A Divet
- Department of Experimental and Diagnostic Medicine, Section of General Pathology, University of Ferrara, Italy
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34
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Kochegarov AA. Therapeutical application of voltage-gated calcium channel modulators. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.12.2.243] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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35
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Benkusky NA, Farrell EF, Valdivia HH. Ryanodine receptor channelopathies. Biochem Biophys Res Commun 2004; 322:1280-5. [PMID: 15336975 DOI: 10.1016/j.bbrc.2004.08.033] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Indexed: 10/26/2022]
Abstract
Ryanodine receptors (RyR) are the Ca2+ release channels of sarcoplasmic reticulum that provide the majority of the [Ca2+] necessary to induce contraction of cardiac and skeletal muscle cells. In their cellular environment, RyRs are exquisitely regulated by a variety of cytosolic factors and accessory proteins so that their output signal (Ca2+) induces cell contraction without igniting signaling pathways that eventually lead to contractile dysfunction or pathological cellular remodeling. Here we review how dysfunction of RyRs, most commonly expressed as enhanced Ca2+ release at rest (skeletal muscle) or during diastole (cardiac muscle), appears to be the fundamental mechanism underlying several genetic or acquired syndromes. In skeletal muscle, malignant hyperthermia and central core disease result from point mutations in RYR1, the skeletal isoform of RyRs. In cardiac muscle, RYR2 mutations lead to catecholaminergic polymorphic ventricular tachycardia and other cardiac arrhythmias. Lastly, an altered phosphorylation of the RyR2 protein may be involved in some forms of congestive heart failure.
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Affiliation(s)
- Nancy A Benkusky
- Department of Physiology, University of Wisconsin Medical School, Madison, WI 53706, USA
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36
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Paolini C, Protasi F, Franzini-Armstrong C. The relative position of RyR feet and DHPR tetrads in skeletal muscle. J Mol Biol 2004; 342:145-53. [PMID: 15313613 DOI: 10.1016/j.jmb.2004.07.035] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2004] [Revised: 07/02/2004] [Accepted: 07/05/2004] [Indexed: 10/26/2022]
Abstract
In skeletal muscle, L-type calcium channels (or dihydropyridine receptors, DHPRs) are coupled functionally to the calcium release channels of the sarcoplasmic reticulum (or ryanodine receptors, RyRs) within specialized structures called calcium release units (CRUs). The functional linkage requires a specific positioning of four DHPRs in correspondence of the four identical subunits of a single RyR type 1. Four DHPRs linked to the four binding sites of the RyR1 cytoplasmic domain (or foot), define the corners of a square, constituting a tetrad. RyRs self-assemble into ordered arrays and by associating with them, DHPRs also assemble into ordered arrays. The approximate location of the four DHPRs relative to the four identical subunits of a RyR-foot can be predicted on the basis of the relative position of tetrads and feet within the arrays. However, until recently one vital piece of information has been lacking: the orientation of the two arrays relative to one another. In this work we have defined the relative orientation of the RyR and DHPR arrays by directly superimposing replicas of rotary shadowed images of rows of feet, obtained from isolated SR vesicles, and replicas of tetrad arrays obtained by freeze-fracture. If the orientation for the two sets of images is carefully maintained, the superimposition provides specific constraints on the DHPR-RyR relative position.
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Affiliation(s)
- Cecilia Paolini
- University of Pennsylvania, Department of Cell & Developmental Biology, Philadelphia 19104-6058, USA.
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37
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Papadopoulos S, Leuranguer V, Bannister RA, Beam KG. Mapping sites of potential proximity between the dihydropyridine receptor and RyR1 in muscle using a cyan fluorescent protein-yellow fluorescent protein tandem as a fluorescence resonance energy transfer probe. J Biol Chem 2004; 279:44046-56. [PMID: 15280389 DOI: 10.1074/jbc.m405317200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Excitation-contraction coupling in skeletal muscle involves conformational coupling between the dihydropyridine receptor (DHPR) and the type 1 ryanodine receptor (RyR1) at junctions between the plasma membrane and sarcoplasmic reticulum. In an attempt to find which regions of these proteins are in close proximity to one another, we have constructed a tandem of cyan and yellow fluorescent proteins (CFP and YFP, respectively) linked by a 23-residue spacer, and measured the fluorescence resonance energy transfer (FRET) of the tandem either in free solution or after attachment to sites of the alpha1S and beta1a subunits of the DHPR. For all of the sites examined, attachment of the CFP-YFP tandem did not impair function of the DHPR as a Ca2+ channel or voltage sensor for excitation-contraction coupling. The free tandem displayed a 27.5% FRET efficiency, which decreased significantly after attachment to the DHPR subunits. At several sites examined for both alpha1S (N-terminal, proximal II-III loop of a two fragment construct) and beta1a (C-terminal), the FRET efficiency was similar after expression in either dysgenic (alpha1S-null) or dyspedic (RyR1-null) myotubes. However, compared with dysgenic myotubes, the FRET efficiency in dyspedic myotubes increased from 9.9 to 16.7% for CFP-YFP attached to the N-terminal of beta1a, and from 9.5 to 16.8% for CFP-YFP at the C-terminal of alpha1S. Thus, the tandem reporter suggests that the C terminus of alpha1S and the N terminus of beta1a may be in close proximity to the ryanodine receptor.
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Affiliation(s)
- Symeon Papadopoulos
- Department of Biomedical Sciences, Anatomy Section, Colorado State University, Fort Collins 80523-1617, USA
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Protasi F, Shtifman A, Julian FJ, Allen PD. All three ryanodine receptor isoforms generate rapid cooling responses in muscle cells. Am J Physiol Cell Physiol 2003; 286:C662-70. [PMID: 14592807 DOI: 10.1152/ajpcell.00081.2003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The rapid cooling (RC) response in muscle is an increase in cytoplasmic Ca2+ concentration ([Ca2+]i) that is probably caused by Ca2+ release from the sarcoplasmic reticulum (SR). However, the molecular bases of this response have not been completely elucidated. Three different isoforms of the SR Ca2+ release channels, or ryanodine receptors (RyRs), have been isolated (RyR1, RyR2, and RyR3). In the current investigation, the RC response was studied in RyR-null muscle cells (1B5) before and after transduction with HSV-1 virions containing the cDNAs encoding for RyR1, RyR2, or RyR3. Cells were loaded with fluo 4-AM to monitor changes in [Ca2+]i and perfused with either cold ( approximately 0 degrees C), room temperature (RT), or RT buffer containing 40 mM caffeine. Control cells showed no significant response to cold or caffeine, whereas robust Ca2+ transients were recorded in response to both RC and caffeine in transduced cells expressing any one of the three RyR isoforms. Our data demonstrate directly that RyRs are responsible for the RC response and that all three isoforms respond in a similar manner. Ca2+ release from RyRs is likely caused by a RC-induced conformational change of the channel from the closed to the open state.
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Affiliation(s)
- Feliciano Protasi
- Department of Anesthesia Research, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachussetts 02115, USA.
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40
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Chen L, Estève E, Sabatier JM, Ronjat M, De Waard M, Allen PD, Pessah IN. Maurocalcine and peptide A stabilize distinct subconductance states of ryanodine receptor type 1, revealing a proportional gating mechanism. J Biol Chem 2003; 278:16095-106. [PMID: 12586831 DOI: 10.1074/jbc.m209501200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Maurocalcine (MCa) isolated from Scorpio maurus palmatus venom shares 82% sequence identity with imperatoxin A. Both scorpion toxins are putative mimics of the II-III loop peptide (termed peptide A (pA)) of alpha(1s)-dihydropyridine receptor and are thought to act at a common site on ryanodine receptor type 1 (RyR1) important for skeletal muscle EC coupling. The relationship between the actions of synthetic MCa (sMCa) and pA on RyR1 were examined. sMCa released Ca(2+) from SR vesicles (EC(50) = 17.5 nm) in a manner inhibited by micromolar ryanodine or ruthenium red. pA (0.5-40 microm) failed to induce SR Ca(2+) release. Rather, pA enhanced Ca(2+) loading into SR and fully inhibited Ca(2+)-, caffeine-, and sMCa-induced Ca(2+) release. The two peptides modified single channel gating behavior in distinct ways. With Cs(+)-carrying current, 10 nm to 1 microm sMCa induced long lived subconductances having 48% of the characteristic full open state and occasional transitions to 29% at either positive or negative holding potentials. In contrast, pA stabilized long lived channel closures with occasional burst transitions to 65% (s1) and 86% (s2) of the full conductance. The actions of pA and sMCa were observed in tandem. sMCa stabilized additional subconductance states proportional to pA-induced subconductances (i.e. 43% of pA-modified s1 and s2 substates), revealing a proportional gating mechanism. [(3)H]Ryanodine binding and surface plasmon resonance analyses indicated that the peptides did not interact by simple competition for a single class of mutually exclusive sites on RyR1 to produce proportional gating. The actions of sMCa were also observed with ryanodine-modified channels and channels deficient in immunophilin 12-kDa FK506-binding protein. These results provide evidence that sMCa and pA stabilize distinct RyR1 channel states through distinct mechanisms that allosterically stabilize gating states having proportional conductance.
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Affiliation(s)
- Lili Chen
- Department of Molecular Biosciences and Graduate Program in Neurosciences, University of California, Davis, CA 95616, USA
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41
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Abstract
Store-operated Ca2+ entry represents an important mechanism for refilling of a depleted intracellular-reticulum Ca2+ store following sustained activation of the IP3 receptor or ryanodine receptor RyR/Ca2+ release channel in the endoplasmic/sarcoplasmic reticulum (ER/SR). Recent studies have demonstrated the existence of store-operated Ca2+ channel (SOC) in muscle cells, whose activation process appears to be coupled to conformational changes of the RyR. Regulation of the plasma membrane (PM)-resided SOC by the SR-located RyR requires an integrity of the junctional membrane structure between SR and PM. Proteins that interact with RyR or influence the Ca2+ buffering capacity in the ER or SR lumen also participate in the activation process of SOC. Calsequestrin (CSQ) and calreticulin (CRT) are SR/ER-resident proteins, with highly negative charged regions at the carboxyl-terminal end that exhibit high buffering capacity for luminal Ca2+. CSQ and CRT not only modulate the intracellular Ca2+ release process but also might provide retrograde signals to regulate the function of SOC. The functional interplay between CSQ, RyR and SOC may serve essential roles of Ca2+ signaling in muscle contraction and development. A tight link between the expression of CRT and operation of SOC exist in certain cancer cells, where the reduced sensitivity to apoptosis may correlate with the altered function of SOC.
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Affiliation(s)
- Jianjie Ma
- Department of Physiology and Biophysics, UMDNJ-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA.
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42
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Zheng Z, Wang ZM, Delbono O. Insulin-like growth factor-1 increases skeletal muscle dihydropyridine receptor alpha 1S transcriptional activity by acting on the cAMP-response element-binding protein element of the promoter region. J Biol Chem 2002; 277:50535-42. [PMID: 12407098 DOI: 10.1074/jbc.m210526200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous work from our laboratory has shown that insulin-like growth factor 1 (IGF-1) increases the expression of the skeletal muscle dihydropyridine receptor (DHPR) alpha(1) subunit by regulating DHPR alpha(1S) nuclear transcription. In this study, we investigated the mechanism by which IGF-1 enhances expression of the DHPR alpha(1S) gene. To this end, the promoter region of the mouse DHPR alpha(1S) gene was recently cloned and sequenced and various promoter deletion-luciferase reporter constructs were used. These constructs were transfected into C2C12 cells and IGF-1 effects were measured by recording luciferase activity. IGF-1 significantly enhanced DHPR alpha(1S) transcription in those constructs carrying cAMP-response element-binding protein (CREB) binding site but not in CREB core binding site mutants. Gel mobility shift assay using a double stranded oligonucleotide for the CREB site in the promoter region, and competition experiments with excess unlabeled or mutated promoter oligonucleotide, and unlabeled consensus CREB oligonucleotide demonstrated that IGF-1 induces CREB binding to the DHPR alpha(1S) promoter. IGF-1-mediated enhancement in charge movement was prevented by incubating the cells with antisense but not with sense oligonucleotides against CREB. These results support the conclusion that IGF-1 regulates DHPR alpha(1S) transcription in muscle cells by acting on the CREB element of the promoter.
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Affiliation(s)
- Zhenlin Zheng
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA
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Michailova A, DelPrincipe F, Egger M, Niggli E. Spatiotemporal features of Ca2+ buffering and diffusion in atrial cardiac myocytes with inhibited sarcoplasmic reticulum. Biophys J 2002; 83:3134-51. [PMID: 12496084 PMCID: PMC1302392 DOI: 10.1016/s0006-3495(02)75317-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Ca(2+) signaling in cells is largely governed by Ca(2+) diffusion and Ca(2+) binding to mobile and stationary Ca(2+) buffers, including organelles. To examine Ca(2+) signaling in cardiac atrial myocytes, a mathematical model of Ca(2+) diffusion was developed which represents several subcellular compartments, including a subsarcolemmal space with restricted diffusion, a myofilament space, and the cytosol. The model was used to quantitatively simulate experimental Ca(2+) signals in terms of amplitude, time course, and spatial features. For experimental reference data, L-type Ca(2+) currents were recorded from atrial cells with the whole-cell voltage-clamp technique. Ca(2+) signals were simultaneously imaged with the fluorescent Ca(2+) indicator Fluo-3 and a laser-scanning confocal microscope. The simulations indicate that in atrial myocytes lacking T-tubules, Ca(2+) movement from the cell membrane to the center of the cells relies strongly on the presence of mobile Ca(2+) buffers, particularly when the sarcoplasmic reticulum is inhibited pharmacologically. Furthermore, during the influx of Ca(2+) large and steep concentration gradients are predicted between the cytosol and the submicroscopically narrow subsarcolemmal space. In addition, the computations revealed that, despite its low Ca(2+) affinity, ATP acts as a significant buffer and carrier for Ca(2+), even at the modest elevations of [Ca(2+)](i) reached during influx of Ca(2+).
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Affiliation(s)
- Anushka Michailova
- Department of Physiology, University of Bern, Buehlplatz 5, CH-3012 Bern, Switzerland.
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44
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Protasi F, Paolini C, Nakai J, Beam KG, Franzini-Armstrong C, Allen PD. Multiple regions of RyR1 mediate functional and structural interactions with alpha(1S)-dihydropyridine receptors in skeletal muscle. Biophys J 2002; 83:3230-44. [PMID: 12496092 PMCID: PMC1302400 DOI: 10.1016/s0006-3495(02)75325-3] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Excitation-contraction (e-c) coupling in muscle relies on the interaction between dihydropyridine receptors (DHPRs) and RyRs within Ca(2+) release units (CRUs). In skeletal muscle this interaction is bidirectional: alpha(1S)DHPRs trigger RyR1 (the skeletal form of the ryanodine receptor) to release Ca(2+) in the absence of Ca(2+) permeation through the DHPR, and RyR1s, in turn, affect the open probability of alpha(1S)DHPRs. alpha(1S)DHPR and RyR1 are linked to each other, organizing alpha(1S)-DHPRs into groups of four, or tetrads. In cardiac muscle, however, alpha(1C)DHPR Ca(2+) current is important for activation of RyR2 (the cardiac isoform of the ryanodine receptor) and alpha(1C)-DHPRs are not organized into tetrads. We expressed RyR1, RyR2, and four different RyR1/RyR2 chimeras (R4: Sk1635-3720, R9: Sk2659-3720, R10: Sk1635-2559, R16: Sk1837-2154) in 1B5 dyspedic myotubes to test their ability to restore skeletal-type e-c coupling and DHPR tetrads. The rank-order for restoring skeletal e-c coupling, indicated by Ca(2+) transients in the absence of extracellular Ca(2+), is RyR1 > R4 > R10 >> R16 > R9 >> RyR2. The rank-order for restoration of DHPR tetrads is RyR1 > R4 = R9 > R10 = R16 >> RyR2. Because the skeletal segment in R9 does not overlap with that in either R10 or R16, our results indicate that multiple regions of RyR1 may interact with alpha(1S)DHPRs and that the regions responsible for tetrad formation do not correspond exactly to the ones required for functional coupling.
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MESH Headings
- Animals
- Caffeine/pharmacology
- Calcium/metabolism
- Calcium Channels/drug effects
- Calcium Channels/physiology
- Calcium Channels/ultrastructure
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/physiology
- Calcium Channels, L-Type/ultrastructure
- Cell Line
- Freeze Fracturing
- Mice
- Microscopy, Electron
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/physiology
- Muscle Fibers, Skeletal/ultrastructure
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/physiology
- Muscle, Skeletal/ultrastructure
- Ryanodine Receptor Calcium Release Channel/drug effects
- Ryanodine Receptor Calcium Release Channel/physiology
- Ryanodine Receptor Calcium Release Channel/ultrastructure
- Structure-Activity Relationship
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Affiliation(s)
- Feliciano Protasi
- Department of Anesthesia Research, Brigham and Women's Hospital, Boston, MA 02115, USA
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45
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Serysheva II, Ludtke SJ, Baker MR, Chiu W, Hamilton SL. Structure of the voltage-gated L-type Ca2+ channel by electron cryomicroscopy. Proc Natl Acad Sci U S A 2002; 99:10370-5. [PMID: 12149473 PMCID: PMC124921 DOI: 10.1073/pnas.162363499] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2002] [Accepted: 06/18/2002] [Indexed: 11/18/2022] Open
Abstract
Voltage-dependent L-type Ca(2+) channels play important functional roles in many excitable cells. We present a three-dimensional structure of an L-type Ca(2+) channel. Electron cryomicroscopy in conjunction with single-particle processing was used to determine a 30-A resolution structure of the channel protein. The asymmetrical channel structure consists of two major regions: a heart-shaped region connected at its widest end with a handle-shaped region. A molecular model is proposed for the arrangement of this skeletal muscle L-type Ca(2+) channel structure with respect to the sarcoplasmic reticulum Ca(2+)-release channel, the physical partner of the L-type channel for signal transduction during the excitation-contraction coupling in muscle.
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Affiliation(s)
- I I Serysheva
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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46
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Pan Z, Yang D, Nagaraj RY, Nosek TA, Nishi M, Takeshima H, Cheng H, Ma J. Dysfunction of store-operated calcium channel in muscle cells lacking mg29. Nat Cell Biol 2002; 4:379-83. [PMID: 11988740 DOI: 10.1038/ncb788] [Citation(s) in RCA: 147] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The store-operated calcium channel (SOC) located in the plasma membrane (PM) mediates capacitative entry of extracellular calcium after depletion of intracellular calcium stores in the endoplasmic or sarcoplasmic reticulum (ER/SR). An intimate interaction between the PM and the ER/SR is essential for the operation of this calcium signalling pathway. Mitsugumin 29 (MG29) is a synaptophysin-family-related protein located in the junction between the PM and SR of skeletal muscle. Here, we identify SOC in skeletal muscle and characterise its regulation by MG29 and the ryanodine receptor (RyR) located in the SR. Targeted deletion of mg29 alters the junctional membrane structure, causes severe dysfunction of SOC and SR calcium homeostasis and increases the susceptibility of muscle to fatigue stimulation. Severe dysfunction of SOC is also identified in muscle cells lacking both type 1 and type 3 RyRs, indicating that SOC activation requires an intact interaction between the PM and the SR, and is linked to conformational changes of RyRs. Whereas defective SOC seems to be inconsequential to short-term excitation-contraction coupling, the slow cumulative calcium entry through SOC is crucial for long-term calcium homeostasis, such that reduced SOC activity exaggerates muscle fatigue under conditions of intensive exercise.
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Affiliation(s)
- Zui Pan
- Department of Physiology and Biophysics, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway NJ 08854, USA
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47
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O'Reilly FM, Robert M, Jona I, Szegedi C, Albrieux M, Geib S, De Waard M, Villaz M, Ronjat M. FKBP12 modulation of the binding of the skeletal ryanodine receptor onto the II-III loop of the dihydropyridine receptor. Biophys J 2002; 82:145-55. [PMID: 11751303 PMCID: PMC1302456 DOI: 10.1016/s0006-3495(02)75381-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In skeletal muscle, excitation-contraction coupling involves a functional interaction between the ryanodine receptor (RyR) and the dihydropyridine receptor (DHPR). The domain corresponding to Thr(671)-Leu(690) of the II-III loop of the skeletal DHPR alpha(1)-subunit is able to regulate RyR properties and calcium release from sarcoplasmic reticulum, whereas the domain corresponding to Glu(724)-Pro(760) antagonizes this effect. Two peptides, covering these sequences (peptide A(Sk) and C(Sk), respectively) were immobilized on polystyrene beads. We demonstrate that peptide A(Sk) binds to the skeletal isoform of RyR (RyR1) whereas peptide C(Sk) does not. Using surface plasmon resonance detection, we show that 1) domain Thr(671)-Leu(690) is the only sequence of the II-III loop binding with RyR1 and 2) the interaction of peptide A(Sk) with RyR1 is not modulated by Ca(2+) (pCa 9-2) nor by Mg(2+) (up to 10 mM). In contrast, this interaction is strongly potentiated by the immunophilin FKBP12 (EC(50) = 10 nM) and inhibited by both rapamycin (IC(50) = 5 nM) and FK506. Peptide A(Sk) induces a 300% increase of the opening probability of the RyR1 incorporated in lipid bilayer. Removal of FKBP12 from RyR1 completely abolishes this effect of domain A(Sk) on RyR1 channel behavior. These results demonstrate a direct interaction of the RyR1 with the discrete domain of skeletal DHPR alpha(1)-subunit corresponding to Thr(671)-Leu(690) and show that the association of FKBP12 with RyR1 specifically modulates this interaction.
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Affiliation(s)
- Fiona M O'Reilly
- Laboratoire Canaux Ioniques et Signalisation, Département de Biologie Moléculaire et Structurale, CEA-Grenoble, F-38054 Grenoble, France
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48
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Yang D, Pan Z, Takeshima H, Wu C, Nagaraj RY, Ma J, Cheng H. RyR3 amplifies RyR1-mediated Ca(2+)-induced Ca(2+) release in neonatal mammalian skeletal muscle. J Biol Chem 2001; 276:40210-4. [PMID: 11500519 DOI: 10.1074/jbc.m106944200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The neonatal mammalian skeletal muscle contains both type 1 and type 3 ryanodine receptors (RyR1 and RyR3) located in the sarcoplasmic reticulum membrane. An allosteric interaction between RyR1 and dihydropyridine receptors located in the plasma membrane mediates voltage-induced Ca(2+) release (VICR) from the sarcoplasmic reticulum. RyR3, which disappears in adult muscle, is not involved in VICR, and the role of the transiently expressed RyR3 remains elusive. Here we demonstrate that RyR1 participates in both VICR and Ca(2+)-induced Ca(2+) release (CICR) and that RyR3 amplifies RyR1-mediated CICR in neonatal skeletal muscle. Confocal measurements of intracellular Ca(2+) in primary cultured mouse skeletal myotubes reveal active sites of Ca(2+) release caused by peripheral coupling between dihydropyridine receptors and RyR1. In myotubes lacking RyR3, the peripheral VICR component is unaffected, and RyR1s alone are able to support inward CICR propagation in most cells at an average speed of approximately 190 microm/s. With the co-presence of RyR1 and RyR3 in wild-type cells, unmitigated radial CICR propagates at 2,440 microm/s. Because neonatal skeletal muscle lacks a well developed transverse tubule system, the RyR3 reinforcement of CICR seems to ensure a robust, uniform, and synchronous activation of Ca(2+) release throughout the cell body. Such functional interplay between RyR1 and RyR3 can serve important roles in Ca(2+) signaling of cell differentiation and muscle contraction.
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Affiliation(s)
- D Yang
- Laboratory of Cardiovascular Science, Gerontology Research Center, NIA National Institutes of Health, Baltimore, MD 21224, USA
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49
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Ursu D, Sebille S, Dietze B, Freise D, Flockerzi V, Melzer W. Excitation-contraction coupling in skeletal muscle of a mouse lacking the dihydropyridine receptor subunit gamma1. J Physiol 2001; 533:367-77. [PMID: 11389198 PMCID: PMC2278637 DOI: 10.1111/j.1469-7793.2001.0367a.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
1. In skeletal muscle, dihydropyridine (DHP) receptors control both Ca(2+) entry (L-type current) and internal Ca(2+) release in a voltage-dependent manner. Here we investigated the question of whether elimination of the skeletal muscle-specific DHP receptor subunit gamma1 affects excitation-contraction (E-C) coupling. We studied intracellular Ca(2+) release and force production in muscle preparations of a mouse deficient in the gamma1 subunit (gamma-/-). 2. The rate of internal Ca(2+) release at large depolarization (+20 mV) was determined in voltage-clamped primary-cultured myotubes derived from satellite cells of adult mice by analysing fura-2 fluorescence signals and estimating the concentration of free and bound Ca(2+). On average, gamma-/- cells showed an increase in release of about one-third of the control value and no alterations in the time course. 3. Voltage of half-maximal activation (V(1/2)) and voltage sensitivity (k) were not significantly different in gamma-/- myotubes, either for internal Ca(2+) release activation or for the simultaneously measured L-type Ca(2+) conductance. The same was true for maximal Ca(2+) inward current and conductance. 4. Contractions evoked by electrical stimuli were recorded in isolated extensor digitorum longus (EDL; fast, glycolytic) and soleus (slow, oxidative) muscles under normal conditions and during fatigue induced by repetitive tetanic stimulation. Neither time course nor amplitudes of twitches and tetani nor force-frequency relations showed significant alterations in the gamma1-deficient muscles. 5. In conclusion, the overall results show that the gamma1 subunit is not essential for voltage-controlled Ca(2+) release and force production.
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MESH Headings
- Action Potentials/physiology
- Animals
- Calcium/metabolism
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Cells, Cultured
- Ion Channel Gating/physiology
- Mice
- Mice, Mutant Strains
- Muscle Contraction/physiology
- Muscle Fatigue/physiology
- Muscle Fibers, Fast-Twitch/cytology
- Muscle Fibers, Fast-Twitch/physiology
- Muscle Fibers, Slow-Twitch/cytology
- Muscle Fibers, Slow-Twitch/physiology
- Muscle, Skeletal/cytology
- Muscle, Skeletal/physiology
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Affiliation(s)
- D Ursu
- Universität Ulm, Abteilung für Angewandte Physiologie, Albert-Einstein-Allee 11, D-89069 Ulm, Germany
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50
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Protasi F, Takekura H, Wang Y, Chen SR, Meissner G, Allen PD, Franzini-Armstrong C. RYR1 and RYR3 have different roles in the assembly of calcium release units of skeletal muscle. Biophys J 2000; 79:2494-508. [PMID: 11053125 PMCID: PMC1301133 DOI: 10.1016/s0006-3495(00)76491-5] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Calcium release units (CRUs) are junctions between the sarcoplasmic reticulum (SR) and exterior membranes that mediates excitation contraction (e-c) coupling in muscle cells. In skeletal muscle CRUs contain two isoforms of the sarcoplasmic reticulum Ca(2+)release channel: ryanodine receptors type 1 and type 3 (RyR1 and RyR3). 1B5s are a mouse skeletal muscle cell line that carries a null mutation for RyR1 and does not express either RyR1 or RyR3. These cells develop dyspedic SR/exterior membrane junctions (i.e., dyspedic calcium release units, dCRUs) that contain dihydropyridine receptors (DHPRs) and triadin, two essential components of CRUs, but no RyRs (or feet). Lack of RyRs in turn affects the disposition of DHPRs, which is normally dictated by a linkage to RyR subunits. In the dCRUs of 1B5 cells, DHPRs are neither grouped into tetrads nor aligned in two orthogonal directions. We have explored the structural role of RyR3 in the assembly of CRUs in 1B5 cells independently expressing either RyR1 or RyR3. Either isoform colocalizes with DHPRs and triadin at the cell periphery. Electron microscopy shows that expression of either isoform results in CRUs containing arrays of feet, indicating the ability of both isoforms to be targeted to dCRUs and to assemble in ordered arrays in the absence of the other. However, a significant difference between RyR1- and RyR3-rescued junctions is revealed by freeze fracture. While cells transfected with RyR1 show restoration of DHPR tetrads and DHPR orthogonal alignment indicative of a link to RyRs, those transfected with RyR3 do not. This indicates that RyR3 fails to link to DHPRs in a specific manner. This morphological evidence supports the hypothesis that activation of RyR3 in skeletal muscle cells must be indirect and provides the basis for failure of e-c coupling in muscle cells containing RyR3 but lacking RyR1 (see the accompanying report, ).
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Affiliation(s)
- F Protasi
- Department of Anesthesia Research, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
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