1
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Zhong R, Rua MT, Wei-LaPierre L. Targeting mitochondrial Ca 2+ uptake for the treatment of amyotrophic lateral sclerosis. J Physiol 2024; 602:1519-1549. [PMID: 38010626 PMCID: PMC11032238 DOI: 10.1113/jp284143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 10/31/2023] [Indexed: 11/29/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a rare adult-onset neurodegenerative disease characterized by progressive motor neuron (MN) loss, muscle denervation and paralysis. Over the past several decades, researchers have made tremendous efforts to understand the pathogenic mechanisms underpinning ALS, with much yet to be resolved. ALS is described as a non-cell autonomous condition with pathology detected in both MNs and non-neuronal cells, such as glial cells and skeletal muscle. Studies in ALS patient and animal models reveal ubiquitous abnormalities in mitochondrial structure and function, and disturbance of intracellular calcium homeostasis in various tissue types, suggesting a pivotal role of aberrant mitochondrial calcium uptake and dysfunctional calcium signalling cascades in ALS pathogenesis. Calcium signalling and mitochondrial dysfunction are intricately related to the manifestation of cell death contributing to MN loss and skeletal muscle dysfunction. In this review, we discuss the potential contribution of intracellular calcium signalling, particularly mitochondrial calcium uptake, in ALS pathogenesis. Functional consequences of excessive mitochondrial calcium uptake and possible therapeutic strategies targeting mitochondrial calcium uptake or the mitochondrial calcium uniporter, the main channel mediating mitochondrial calcium influx, are also discussed.
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Affiliation(s)
- Renjia Zhong
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, 32611
- Department of Emergency Medicine, the First Affiliated Hospital of China Medical University, Shenyang, Liaoning, China, 110001
| | - Michael T. Rua
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, 32611
| | - Lan Wei-LaPierre
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, 32611
- Myology Institute, University of Florida, Gainesville, FL 32611
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2
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Nuzhnyi EP, Arestova AS, Rossokhin AV, Protopopova AO, Abramycheva NY, Suponeva NA, Illarioshkin SN. Case report: A novel CACNA1S mutation associated with hypokalemic periodic paralysis. Front Neurol 2023; 14:1267426. [PMID: 37840943 PMCID: PMC10570449 DOI: 10.3389/fneur.2023.1267426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 09/14/2023] [Indexed: 10/17/2023] Open
Abstract
Background Hypokalemic periodic paralysis (HypoKPP) is a rare neuromuscular genetic disorder causing recurrent episodes of flaccid paralysis. Most cases are associated with CACNA1S mutation, causing defect of calcium channel and subsequent impairment of muscle functions. Due to defined management approaches early diagnosis is crucial for promptly treatment and prevention new attacks. Materials and methods We report a case of HypoKPP associated with previously unreported mutation in CACNA1S gene (p.R900M). Molecular modeling of CaV1.1 was applied to evaluate its pathogenicity. Results As a patient referred between attacks neurological status, laboratory and neurophysiological examination were unremarkable. Molecular modeling predicted that the p.R900M mutation affects the process of calcium channels activation. Conclusion Novel CACNA1S mutation, associated with HypoKPP was identified. Monte-Carlo energy minimization of the CaV1.1 model supported the association of this mutation with this disease.
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Szentesi P, Dienes B, Kutchukian C, Czirjak T, Buj-Bello A, Jacquemond V, Csernoch L. Disrupted T-tubular network accounts for asynchronous calcium release in MTM1-deficient skeletal muscle. J Physiol 2023; 601:99-121. [PMID: 36408764 PMCID: PMC10107287 DOI: 10.1113/jp283650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 11/14/2022] [Indexed: 11/22/2022] Open
Abstract
In mammalian skeletal muscle, the propagation of surface membrane depolarization into the interior of the muscle fibre along the transverse (T) tubular network is essential for the synchronized release of calcium from the sarcoplasmic reticulum (SR) via ryanodine receptors (RyRs) in response to the conformational change in the voltage-sensor dihydropyridine receptors. Deficiency in 3-phosphoinositide phosphatase myotubularin (MTM1) has been reported to disrupt T-tubules, resulting in impaired SR calcium release. Here confocal calcium transients recorded in muscle fibres of MTM1-deficient mice were compared with the results from a model where propagation of the depolarization along the T-tubules was modelled mathematically with disruptions in the network assumed to modify the access and transmembrane resistance as well as the capacitance. If, in simulations, T-tubules were assumed to be partially or completely inaccessible to the depolarization and RyRs at these points to be prime for calcium-induced calcium release, all the features of measured SR calcium release could be reproduced. We conclude that the inappropriate propagation of the depolarization into the fibre interior is the initial critical cause of severely impaired SR calcium release in MTM1 deficiency, while the Ca2+ -triggered opening of RyRs provides an alleviating support to the diseased process. KEY POINTS: Myotubular myopathy is a fatal disease due to genetic deficiency in the phosphoinositide phosphatase MTM1. Although the causes are known and corresponding gene therapy strategies are being developed, there is no mechanistic understanding of the disease-associated muscle function failure. Resolving this issue is of primary interest not only for a fundamental understanding of how MTM1 is critical for healthy muscle function, but also for establishing the related cellular mechanisms most primarily or stringently affected by the disease, which are thus of potential interest as therapy targets. The mathematical modelling approach used in the present work proves that the disease-associated alteration of the plasma membrane invagination network is sufficient to explain the dysfunctions of excitation-contraction coupling, providing the first integrated quantitative framework that explains the associated contraction failure.
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Affiliation(s)
- Peter Szentesi
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Beatrix Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Candice Kutchukian
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR-5261, INSERM U-1315, Institut NeuroMyoGène, Lyon, France
| | - Tamas Czirjak
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Ana Buj-Bello
- Genethon, Evry, France.,Université Paris-Saclay, Evry, France
| | - Vincent Jacquemond
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR-5261, INSERM U-1315, Institut NeuroMyoGène, Lyon, France
| | - László Csernoch
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,ELRN-UD Cell Physiology Research Group, Debrecen, Hungary
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4
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Michelucci A, Pietrangelo L, Rastelli G, Protasi F, Dirksen RT, Boncompagni S. Constitutive assembly of Ca2+ entry units in soleus muscle from calsequestrin knockout mice. J Gen Physiol 2022; 154:213542. [PMID: 36222861 PMCID: PMC9565155 DOI: 10.1085/jgp.202213114] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 07/05/2022] [Accepted: 07/27/2022] [Indexed: 12/25/2022] Open
Abstract
Calcium (Ca2+) entry units (CEUs) are junctions within the I band of the sarcomere between stacks of sarcoplasmic reticulum (SR) cisternae and extensions of the transverse (T)-tubule. CEUs contain STIM1 and Orai1 proteins, the molecular machinery of store-operated Ca2+ entry (SOCE). In extensor digitorum longus (EDL) fibers of wild-type (WT) mice, CEUs transiently assemble during acute exercise and disassemble several hours thereafter. By contrast, calsequestrin-1 (CASQ1) ablation induces a compensatory constitutive assembly of CEUs in EDL fibers, resulting in enhanced constitutive and maximum SOCE that counteracts SR Ca2+ depletion during repetitive activity. However, whether CEUs form in slow-twitch fibers, which express both the skeletal CASQ1 and the cardiac CASQ2 isoforms, is unknown. Herein, we compared the structure and function of soleus muscles from WT and knockout mice that lack either CASQ1 (CASQ1-null) or both CASQs (dCASQ-null). Ultrastructural analyses showed that SR/T-tubule junctions at the I band, virtually identical to CEUs in EDL muscle, were present and more frequent in CASQ1-null than WT mice, with dCASQ-null exhibiting the highest incidence. The greater incidence of CEUs in soleus from dCASQ-null mice correlated with increased specific force production during repetitive, high-frequency stimulation, which depended on Ca2+ entry. Consistent with this, Orai1 expression was significantly increased in soleus of CASQ1-null mice, but even more in dCASQ-null mice, compared with WT. Together, these results strengthen the concept that CEU assembly strongly depends on CASQ expression and provides an alternative source of Ca2+ needed to refill SR Ca2+ stores to maintain specific force production during sustained muscle activity.
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Affiliation(s)
- Antonio Michelucci
- Center for Advanced Studies and Technology, University G. d'Annunzio of Chieti-Pescara, Chieti, Italy.,Department of Chemistry, Biology, and Biotechnology, University of Perugia, Perugia, 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
| | - Giorgia Rastelli
- Center for Advanced Studies and Technology, University G. d'Annunzio of Chieti-Pescara, Chieti, Italy
| | - 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
| | - Robert T Dirksen
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester, Rochester, NY
| | - Simona Boncompagni
- 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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5
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Savalli N, Angelini M, Steccanella F, Wier J, Wu F, Quinonez M, DiFranco M, Neely A, Cannon SC, Olcese R. The distinct role of the four voltage sensors of the skeletal CaV1.1 channel in voltage-dependent activation. J Gen Physiol 2021; 153:212652. [PMID: 34546289 PMCID: PMC8460119 DOI: 10.1085/jgp.202112915] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 08/22/2021] [Indexed: 11/30/2022] Open
Abstract
Initiation of skeletal muscle contraction is triggered by rapid activation of RYR1 channels in response to sarcolemmal depolarization. RYR1 is intracellular and has no voltage-sensing structures, but it is coupled with the voltage-sensing apparatus of CaV1.1 channels to inherit voltage sensitivity. Using an opto-electrophysiological approach, we resolved the excitation-driven molecular events controlling both CaV1.1 and RYR1 activations, reported as fluorescence changes. We discovered that each of the four human CaV1.1 voltage-sensing domains (VSDs) exhibits unique biophysical properties: VSD-I time-dependent properties were similar to ionic current activation kinetics, suggesting a critical role of this voltage sensor in CaV1.1 activation; VSD-II, VSD-III, and VSD-IV displayed faster activation, compatible with kinetics of sarcoplasmic reticulum Ca2+ release. The prominent role of VSD-I in governing CaV1.1 activation was also confirmed using a naturally occurring, charge-neutralizing mutation in VSD-I (R174W). This mutation abolished CaV1.1 current at physiological membrane potentials by impairing VSD-I activation without affecting the other VSDs. Using a structurally relevant allosteric model of CaV activation, which accounted for both time- and voltage-dependent properties of CaV1.1, to predict VSD-pore coupling energies, we found that VSD-I contributed the most energy (~75 meV or ∼3 kT) toward the stabilization of the open states of the channel, with smaller (VSD-IV) or negligible (VSDs II and III) energetic contribution from the other voltage sensors (<25 meV or ∼1 kT). This study settles the longstanding question of how CaV1.1, a slowly activating channel, can trigger RYR1 rapid activation, and reveals a new mechanism for voltage-dependent activation in ion channels, whereby pore opening of human CaV1.1 channels is primarily driven by the activation of one voltage sensor, a mechanism distinct from that of all other voltage-gated channels.
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Affiliation(s)
- Nicoletta Savalli
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA
| | - Marina Angelini
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA
| | - Federica Steccanella
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA
| | - Julian Wier
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA
| | - Fenfen Wu
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA
| | - Marbella Quinonez
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA
| | - Marino DiFranco
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA
| | - Alan Neely
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA.,Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Stephen C Cannon
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA
| | - Riccardo Olcese
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA.,Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA
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6
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A novel RyR1-selective inhibitor prevents and rescues sudden death in mouse models of malignant hyperthermia and heat stroke. Nat Commun 2021; 12:4293. [PMID: 34257294 PMCID: PMC8277899 DOI: 10.1038/s41467-021-24644-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 06/29/2021] [Indexed: 12/03/2022] Open
Abstract
Mutations in the type 1 ryanodine receptor (RyR1), a Ca2+ release channel in skeletal muscle, hyperactivate the channel to cause malignant hyperthermia (MH) and are implicated in severe heat stroke. Dantrolene, the only approved drug for MH, has the disadvantages of having very poor water solubility and long plasma half-life. We show here that an oxolinic acid-derivative RyR1-selective inhibitor, 6,7-(methylenedioxy)-1-octyl-4-quinolone-3-carboxylic acid (Compound 1, Cpd1), effectively prevents and treats MH and heat stroke in several mouse models relevant to MH. Cpd1 reduces resting intracellular Ca2+, inhibits halothane- and isoflurane-induced Ca2+ release, suppresses caffeine-induced contracture in skeletal muscle, reduces sarcolemmal cation influx, and prevents or reverses the fulminant MH crisis induced by isoflurane anesthesia and rescues animals from heat stroke caused by environmental heat stress. Notably, Cpd1 has great advantages of better water solubility and rapid clearance in vivo over dantrolene. Cpd1 has the potential to be a promising candidate for effective treatment of patients carrying RyR1 mutations. Mutations in ryanodine receptor 1 (RyR1), a Ca2+ release channel in skeletal muscle, cause malignant hyperthermia (MH) and are involved in heat stroke. Here, the authors show that an oxolinic acid-derivative RyR1 inhibitor effectively prevents and treats MH and heat stroke in various MH mouse models.
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7
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Michelucci A, Liang C, Protasi F, Dirksen RT. Altered Ca 2+ Handling and Oxidative Stress Underlie Mitochondrial Damage and Skeletal Muscle Dysfunction in Aging and Disease. Metabolites 2021; 11:metabo11070424. [PMID: 34203260 PMCID: PMC8304741 DOI: 10.3390/metabo11070424] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 06/22/2021] [Accepted: 06/24/2021] [Indexed: 12/26/2022] Open
Abstract
Skeletal muscle contraction relies on both high-fidelity calcium (Ca2+) signals and robust capacity for adenosine triphosphate (ATP) generation. Ca2+ release units (CRUs) are highly organized junctions between the terminal cisternae of the sarcoplasmic reticulum (SR) and the transverse tubule (T-tubule). CRUs provide the structural framework for rapid elevations in myoplasmic Ca2+ during excitation-contraction (EC) coupling, the process whereby depolarization of the T-tubule membrane triggers SR Ca2+ release through ryanodine receptor-1 (RyR1) channels. Under conditions of local or global depletion of SR Ca2+ stores, store-operated Ca2+ entry (SOCE) provides an additional source of Ca2+ that originates from the extracellular space. In addition to Ca2+, skeletal muscle also requires ATP to both produce force and to replenish SR Ca2+ stores. Mitochondria are the principal intracellular organelles responsible for ATP production via aerobic respiration. This review provides a broad overview of the literature supporting a role for impaired Ca2+ handling, dysfunctional Ca2+-dependent production of reactive oxygen/nitrogen species (ROS/RNS), and structural/functional alterations in CRUs and mitochondria in the loss of muscle mass, reduction in muscle contractility, and increase in muscle damage in sarcopenia and a wide range of muscle disorders including muscular dystrophy, rhabdomyolysis, central core disease, and disuse atrophy. Understanding the impact of these processes on normal muscle function will provide important insights into potential therapeutic targets designed to prevent or reverse muscle dysfunction during aging and disease.
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Affiliation(s)
- Antonio Michelucci
- DNICS, Department of Neuroscience, Imaging, and Clinical Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
- Correspondence:
| | - Chen Liang
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, NY 14642, USA; (C.L.); (R.T.D.)
| | - Feliciano Protasi
- CAST, Center for Advanced Studies and Technology, DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy;
| | - Robert T. Dirksen
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, NY 14642, USA; (C.L.); (R.T.D.)
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8
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Choi JH, Jeong SY, Oh MR, Allen PD, Lee EH. TRPCs: Influential Mediators in Skeletal Muscle. Cells 2020; 9:cells9040850. [PMID: 32244622 PMCID: PMC7226745 DOI: 10.3390/cells9040850] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 03/31/2020] [Accepted: 03/31/2020] [Indexed: 02/07/2023] Open
Abstract
Ca2+ itself or Ca2+-dependent signaling pathways play fundamental roles in various cellular processes from cell growth to death. The most representative example can be found in skeletal muscle cells where a well-timed and adequate supply of Ca2+ is required for coordinated Ca2+-dependent skeletal muscle functions, such as the interactions of contractile proteins during contraction. Intracellular Ca2+ movements between the cytosol and sarcoplasmic reticulum (SR) are strictly regulated to maintain the appropriate Ca2+ supply in skeletal muscle cells. Added to intracellular Ca2+ movements, the contribution of extracellular Ca2+ entry to skeletal muscle functions and its significance have been continuously studied since the early 1990s. Here, studies on the roles of channel proteins that mediate extracellular Ca2+ entry into skeletal muscle cells using skeletal myoblasts, myotubes, fibers, tissue, or skeletal muscle-originated cell lines are reviewed with special attention to the proposed functions of transient receptor potential canonical proteins (TRPCs) as store-operated Ca2+ entry (SOCE) channels under normal conditions and the potential abnormal properties of TRPCs in muscle diseases such as Duchenne muscular dystrophy (DMD).
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Affiliation(s)
- Jun Hee Choi
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
- Department of Biomedicine & Health Sciences, Graduate School, The Catholic University of Korea, Seoul 06591, Korea
| | - Seung Yeon Jeong
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
- Department of Biomedicine & Health Sciences, Graduate School, The Catholic University of Korea, Seoul 06591, Korea
| | - Mi Ri Oh
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
- Department of Biomedicine & Health Sciences, Graduate School, The Catholic University of Korea, Seoul 06591, Korea
| | - Paul D. Allen
- Leeds Institute of Biomedical & Clinical Sciences, St. James’s University Hospital, University of Leeds, Leeds LS97TF, UK
| | - Eun Hui Lee
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
- Department of Biomedicine & Health Sciences, Graduate School, The Catholic University of Korea, Seoul 06591, Korea
- Correspondence: ; Tel.: +82-2-2258-7279
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Mohamed Thangal SN, Donelan JM. Scaling of inertial delays in terrestrial mammals. PLoS One 2020; 15:e0217188. [PMID: 32017765 PMCID: PMC6999919 DOI: 10.1371/journal.pone.0217188] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 01/12/2020] [Indexed: 11/18/2022] Open
Abstract
As part of its response to a perturbation, an animal often needs to reposition its body. Inertia acts to oppose the corrective motion, delaying the completion of the movement-we refer to this elapsed time as inertial delay. As animal size increases, muscle moment arms also increase, but muscles are proportionally weaker, and limb inertia is proportionally larger. Consequently, the scaling of inertial delays is complex. Our intent is to determine how quickly different sized animals can produce corrective movements when their muscles act at their force capacity, relative to the time within which those movements need to be performed. Here, we quantify inertial delay using two biomechanical models representing common scenarios in animal locomotion: a distributed mass pendulum approximating swing limb repositioning (swing task), and an inverted pendulum approximating whole body posture recovery (posture task). We parameterized the anatomical, muscular, and inertial properties of these models using literature scaling relationships, then determined inertial delay for each task across a large range of movement magnitudes and the full range of terrestrial mammal sizes. We found that inertial delays scaled with an average of M0.28 in the swing task and M0.35 in the posture task across movement magnitudes-larger animals require more absolute time to perform the same movement as small animals. The time available to complete a movement also increases with animal size, but less steeply. Consequently, inertial delays comprise a greater fraction of swing duration and other characteristic movement times in larger animals. We also compared inertial delays to the other component delays within the stimulus-response pathway. As movement magnitude increased, inertial delays exceeded these sensorimotor delays, and this occurred for smaller movements in larger animals. Inertial delays appear to be a challenge for motor control, particularly for bigger movements in larger animals.
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Affiliation(s)
| | - J. Maxwell Donelan
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
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10
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Molecular determinants of homo- and heteromeric interactions of Junctophilin-1 at triads in adult skeletal muscle fibers. Proc Natl Acad Sci U S A 2019; 116:15716-15724. [PMID: 31315980 DOI: 10.1073/pnas.1820980116] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In adult skeletal muscles, 2 junctophilin isoforms (JPH1 and JPH2) tether the sarcoplasmic reticulum (SR) to transverse tubule (T-tubule) membranes, generating stable membrane contact sites known as triads. JPHs are anchored to the membrane of the SR by a C-terminal transmembrane domain (TMD) and bind the T-tubule membrane through their cytosolic N-terminal region, which contains 8 lipid-binding (MORN) motifs. By combining expression of GFP-JPH1 deletion mutants in skeletal muscle fibers with in vitro biochemical experiments, we investigated the molecular determinants of JPH1 recruitment at triads in adult skeletal muscle fibers. We found that MORN motifs bind PI(4,5)P2 in the sarcolemma, but do not mediate the selective localization of JPH1 at the T-tubule compartment of triads. On the contrary, fusion proteins containing only the TMD of JPH1 were able to localize at the junctional SR compartment of the triad. Bimolecular fluorescence complementation experiments indicated that the TMD of JPH1 can form dimers, suggesting that the observed localization at triads may result from dimerization with the TMDs of resident JPH1. A second domain, capable of mediating homo- and heterodimeric interactions between JPH1 and JPH2 was identified in the cytosolic region. FRAP experiments revealed that removal of either one of these 2 domains in JPH1 decreases the association of the resulting mutant proteins with triads. Altogether, these results suggest that the ability to establish homo- and heterodimeric interactions with resident JPHs may support the recruitment and stability of newly synthesized JPHs at triads in adult skeletal muscle fibers.
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11
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Ca 2+-induced sarcoplasmic reticulum Ca 2+ release in myotubularin-deficient muscle fibers. Cell Calcium 2019; 80:91-100. [PMID: 30999217 DOI: 10.1016/j.ceca.2019.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 03/27/2019] [Accepted: 04/08/2019] [Indexed: 11/23/2022]
Abstract
Skeletal muscle deficiency in the 3-phosphoinositide (PtdInsP) phosphatase myotubularin (MTM1) causes myotubular myopathy which is associated with severe depression of voltage-activated sarcoplasmic reticulum Ca2+ release through ryanodine receptors. In the present study we aimed at further understanding how Ca2+ release is altered in MTM1-deficient muscle fibers, at rest and during activation. While in wild-type muscle fibers, SR Ca2+ release exhibits fast stereotyped kinetics of activation and decay throughout the voltage range of activation, Ca2+ release in MTM1-deficient muscle fibers exhibits slow and unconventional kinetics at intermediate voltages, suggestive of partial loss of the normal control of ryanodine receptor Ca2+ channel activity. In addition, the diseased muscle fibers at rest exhibit spontaneous elementary Ca2+ release events at a frequency 30 times greater than that of control fibers. Eighty percent of the events have spatiotemporal properties of archetypal Ca2+ sparks while the rest take either the form of lower amplitude, longer duration Ca2+ release events or of a combination thereof. The events occur at preferred locations in the fibers, indicating spatially uneven distribution of the parameters determining spontaneous ryanodine receptor 1 opening. Spatially large Ca2+ release sources were obviously involved in some of these events, suggesting that opening of ryanodine receptors in one cluster can activate opening of ryanodine receptors in a neighboring one. Overall results demonstrate that opening of Ca2+-activated ryanodine receptors is promoted both at rest and during excitation-contraction coupling in MTM1-deficient muscle fibers. Because access to this activation mode is denied to ryanodine receptors in healthy skeletal muscle, this may play an important role in the associated disease situation.
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12
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Niu J, Yang W, Yue DT, Inoue T, Ben-Johny M. Duplex signaling by CaM and Stac3 enhances Ca V1.1 function and provides insights into congenital myopathy. J Gen Physiol 2018; 150:1145-1161. [PMID: 29950399 PMCID: PMC6080896 DOI: 10.1085/jgp.201812005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 03/23/2018] [Accepted: 05/11/2018] [Indexed: 01/24/2023] Open
Abstract
CaV1.1 is essential for skeletal muscle excitation-contraction coupling. Its functional expression is tuned by numerous regulatory proteins, yet underlying modulatory mechanisms remain ambiguous as CaV1.1 fails to function in heterologous systems. In this study, by dissecting channel trafficking versus gating, we evaluated the requirements for functional CaV1.1 in heterologous systems. Although coexpression of the auxiliary β subunit is sufficient for surface-membrane localization, this baseline trafficking is weak, and channels elicit a diminished open probability. The regulatory proteins calmodulin and stac3 independently enhance channel trafficking and gating via their interaction with the CaV1.1 carboxy terminus. Myopathic stac3 mutations weaken channel binding and diminish trafficking. Our findings demonstrate that multiple regulatory proteins orchestrate CaV1.1 function via duplex mechanisms. Our work also furnishes insights into the pathophysiology of stac3-associated congenital myopathy and reveals novel avenues for pharmacological intervention.
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Affiliation(s)
- Jacqueline Niu
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD
| | - Wanjun Yang
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD
| | | | - Takanari Inoue
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD
- Center for Cell Dynamics, Institute for Basic Biomedical Sciences, Johns Hopkins University, Baltimore, MD
| | - Manu Ben-Johny
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY
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Avila-Medina J, Mayoral-Gonzalez I, Dominguez-Rodriguez A, Gallardo-Castillo I, Ribas J, Ordoñez A, Rosado JA, Smani T. The Complex Role of Store Operated Calcium Entry Pathways and Related Proteins in the Function of Cardiac, Skeletal and Vascular Smooth Muscle Cells. Front Physiol 2018; 9:257. [PMID: 29618985 PMCID: PMC5872157 DOI: 10.3389/fphys.2018.00257] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 03/06/2018] [Indexed: 12/11/2022] Open
Abstract
Cardiac, skeletal, and smooth muscle cells shared the common feature of contraction in response to different stimuli. Agonist-induced muscle's contraction is triggered by a cytosolic free Ca2+ concentration increase due to a rapid Ca2+ release from intracellular stores and a transmembrane Ca2+ influx, mainly through L-type Ca2+ channels. Compelling evidences have demonstrated that Ca2+ might also enter through other cationic channels such as Store-Operated Ca2+ Channels (SOCCs), involved in several physiological functions and pathological conditions. The opening of SOCCs is regulated by the filling state of the intracellular Ca2+ store, the sarcoplasmic reticulum, which communicates to the plasma membrane channels through the Stromal Interaction Molecule 1/2 (STIM1/2) protein. In muscle cells, SOCCs can be mainly non-selective cation channels formed by Orai1 and other members of the Transient Receptor Potential-Canonical (TRPC) channels family, as well as highly selective Ca2+ Release-Activated Ca2+ (CRAC) channels, formed exclusively by subunits of Orai proteins likely organized in macromolecular complexes. This review summarizes the current knowledge of the complex role of Store Operated Calcium Entry (SOCE) pathways and related proteins in the function of cardiac, skeletal, and vascular smooth muscle cells.
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Affiliation(s)
- Javier Avila-Medina
- Department of Medical Physiology and Biophysics, University of Seville, Sevilla, Spain.,Institute of Biomedicine of Seville, University Hospital of Virgen del Rocío, CSIC, University of Seville, Sevilla, Spain.,CIBERCV, Madrid, Spain
| | | | - Alejandro Dominguez-Rodriguez
- Department of Medical Physiology and Biophysics, University of Seville, Sevilla, Spain.,Institute of Biomedicine of Seville, University Hospital of Virgen del Rocío, CSIC, University of Seville, Sevilla, Spain.,CIBERCV, Madrid, Spain
| | | | - Juan Ribas
- Department of Medical Physiology and Biophysics, University of Seville, Sevilla, Spain
| | - Antonio Ordoñez
- CIBERCV, Madrid, Spain.,Department of Surgery, University of Seville, Sevilla, Spain
| | - Juan A Rosado
- Cell Physiology Research Group, Department of Physiology, Institute of Molecular Pathology Biomarkers, University of Extremadura, Cáceres, Spain
| | - Tarik Smani
- Department of Medical Physiology and Biophysics, University of Seville, Sevilla, Spain.,Institute of Biomedicine of Seville, University Hospital of Virgen del Rocío, CSIC, University of Seville, Sevilla, Spain.,CIBERCV, Madrid, Spain
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14
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Kutchukian C, Szentesi P, Allard B, Trochet D, Beuvin M, Berthier C, Tourneur Y, Guicheney P, Csernoch L, Bitoun M, Jacquemond V. Impaired excitation-contraction coupling in muscle fibres from the dynamin2 R465W mouse model of centronuclear myopathy. J Physiol 2017; 595:7369-7382. [PMID: 29071728 DOI: 10.1113/jp274990] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 10/20/2017] [Indexed: 01/25/2023] Open
Abstract
KEY POINTS Dynamin 2 is a ubiquitously expressed protein involved in membrane trafficking processes. Mutations in the gene encoding dynamin 2 are responsible for a congenital myopathy associated with centrally located nuclei in the muscle fibres. Using muscle fibres from a mouse model of the most common mutation responsible for this disease in humans, we tested whether altered Ca2+ signalling and excitation-contraction coupling contribute to muscle weakness. The plasma membrane network that carries the electrical excitation is moderately perturbed in the diseased muscle fibres. The excitation-activated Ca2+ input fluxes across both the plasma membrane and the membrane of the sarcoplasmic reticulum are defective in the diseased fibres, which probably contributes to muscle weakness in patients. ABSTRACT Mutations in the gene encoding dynamin 2 (DNM2) are responsible for autosomal dominant centronuclear myopathy (AD-CNM). We studied the functional properties of Ca2+ signalling and excitation-contraction (EC) coupling in muscle fibres isolated from a knock-in (KI) mouse model of the disease, using confocal imaging and the voltage clamp technique. The transverse-tubule network organization appeared to be unaltered in the diseased fibres, although its density was reduced by ∼10% compared to that in control fibres. The density of Ca2+ current through CaV1.1 channels and the rate of voltage-activated sarcoplasmic reticulum Ca2+ release were reduced by ∼60% and 30%, respectively, in KI vs. control fibres. In addition, Ca2+ release in the KI fibres reached its peak value 10-50 ms later than in control ones. Activation of Ca2+ transients along the longitudinal axis of the fibres was more heterogeneous in the KI than in the control fibres, with the difference being exacerbated at intermediate membrane voltages. KI fibres exhibited spontaneous Ca2+ release events that were almost absent from control fibres. Overall, the results of the present study demonstrate that Ca2+ signalling and EC coupling exhibit a number of dysfunctions likely contributing to muscle weakness in DNM2-related AD-CNM.
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Affiliation(s)
- Candice Kutchukian
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR-5310, INSERM U-1217, Institut NeuroMyoGène, Villeurbanne, France
| | - Peter Szentesi
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Bruno Allard
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR-5310, INSERM U-1217, Institut NeuroMyoGène, Villeurbanne, France
| | - Delphine Trochet
- Research Center for Myology, UPMC Univ Paris 06 and INSERM UMR_S974, Institute of Myology, Paris, France
| | - Maud Beuvin
- Research Center for Myology, UPMC Univ Paris 06 and INSERM UMR_S974, Institute of Myology, Paris, France
| | - Christine Berthier
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR-5310, INSERM U-1217, Institut NeuroMyoGène, Villeurbanne, France
| | - Yves Tourneur
- CarMeN, INSERM U1060, Faculté de Médecine Lyon Sud, Oullins, France.,UFPE Dept Nutrição, Av. Prof. Moraes Rego, Cidade Universitária, Recife, Brazil
| | - Pascale Guicheney
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMR_S1166, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France
| | - Laszlo Csernoch
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Marc Bitoun
- Research Center for Myology, UPMC Univ Paris 06 and INSERM UMR_S974, Institute of Myology, Paris, France
| | - Vincent Jacquemond
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR-5310, INSERM U-1217, Institut NeuroMyoGène, Villeurbanne, France
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15
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Barker RG, Horvath D, van der Poel C, Murphy RM. Benefits of Prenatal Taurine Supplementation in Preventing the Onset of Acute Damage in the Mdx Mouse. PLOS CURRENTS 2017; 9:ecurrents.md.9a3e357a0154d01050b591601cbd4fdb. [PMID: 29188135 PMCID: PMC5693597 DOI: 10.1371/currents.md.9a3e357a0154d01050b591601cbd4fdb] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
INTRODUCTION Duchenne Muscular Dystrophy (DMD) is a debilitating muscle wasting disorder with no cure. Safer supplements and therapies are needed to improve the severity of symptoms, as severe side effects are associated with the only effective treatment, corticosteroids. The amino acid taurine has shown promise in ameliorating dystrophic symptoms in mdx mice, an animal model of DMD, however little work is in 21-28 (d)ay animals, the period of natural peak damage. METHODS This study compares the effect of prenatal taurine supplementation on tibialis anterior (TA) in situ contractile function, histopathological characteristics and the abundance of Ca2+-handling as well as pathologically relevant proteins in non-exercised mdx mice at 28 and 70 d. RESULTS Supplementation elevated TA taurine content by 25% (p<0.05), ameliorated in situ specific force by 60% (p<0.05) and improved histological characteristics in 28 d mdx mice; however no benefit was seen in 70 d mice, where background pathology was initially stable. Age specific effects in SERCA1, calsequestrin 1 (CSQ1), CSQ2, utrophin and myogenin protein abundances were seen between both 28 and 70 d mdx and mdx taurine-supplemented mice. DISCUSSION Considering these findings and that taurine is a relatively cost effective, readily accessible and side effect free dietary supplement, we propose further investigation into taurine supplementation during pregnancy in a protective capacity, reminiscent of folate in the prevention of spinal bifida.
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Affiliation(s)
- Robert G Barker
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Melbourne, Victoria, Australia
| | - Deanna Horvath
- Department of Physiology, Anatomy, and Microbiology, La Trobe University, Melbourne, Victoria, Australia
| | - Chris van der Poel
- Department of Physiology, Anatomy, and Microbiology, La Trobe University, Melbourne, Victoria, Australia
| | - Robyn M Murphy
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Melbourne, Victoria, Australia
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16
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Phosphatidylinositol 3-kinase inhibition restores Ca2+ release defects and prolongs survival in myotubularin-deficient mice. Proc Natl Acad Sci U S A 2016; 113:14432-14437. [PMID: 27911767 DOI: 10.1073/pnas.1604099113] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Mutations in the gene encoding the phosphoinositide 3-phosphatase myotubularin (MTM1) are responsible for a pediatric disease of skeletal muscle named myotubular myopathy (XLMTM). Muscle fibers from MTM1-deficient mice present defects in excitation-contraction (EC) coupling likely responsible for the disease-associated fatal muscle weakness. However, the mechanism leading to EC coupling failure remains unclear. During normal skeletal muscle EC coupling, transverse (t) tubule depolarization triggers sarcoplasmic reticulum (SR) Ca2+ release through ryanodine receptor channels gated by conformational coupling with the t-tubule voltage-sensing dihydropyridine receptors. We report that MTM1 deficiency is associated with a 60% depression of global SR Ca2+ release over the full range of voltage sensitivity of EC coupling. SR Ca2+ release in the diseased fibers is also slower than in normal fibers, or delayed following voltage activation, consistent with the contribution of Ca2+-gated ryanodine receptors to EC coupling. In addition, we found that SR Ca2+ release is spatially heterogeneous within myotubularin-deficient muscle fibers, with focally defective areas recapitulating the global alterations. Importantly, we found that pharmacological inhibition of phosphatidylinositol 3-kinase (PtdIns 3-kinase) activity rescues the Ca2+ release defects in isolated muscle fibers and increases the lifespan and mobility of XLMTM mice, providing proof of concept for the use of PtdIns 3-kinase inhibitors in myotubular myopathy and suggesting that unbalanced PtdIns 3-kinase activity plays a critical role in the pathological process.
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17
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Sheu SY, Schlag EW, Yang DY. A model for ultra-fast charge transport in membrane proteins. Phys Chem Chem Phys 2016; 17:23088-94. [PMID: 26274051 DOI: 10.1039/c5cp01442e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Isolated proteins have recently been observed to transport charge and reactivity over very long distances with extraordinary rates and near perfect efficiencies in spite of their site. This is not the case if the peptide is in water, where the efficiency of charge hopping to the next site is reduced to approximately 2%. Here, water is not an ideal solvent for charge transport. The issue at hand is how to explain such enormous charge transfer quenching in water compared to another typical medium, namely lipid. We performed molecular dynamics simulations to computationally substantiate the novel long-distance charge transfer yield of the polypeptides in lipids. This is characterized by the charge transfer persistent-distance decay constant and not by the rate, which is seldom, if ever, measured and hence not directly addressed here. This model can encompass an extremely wide range of yields over very long distances in peptides in various media. The calculations here demonstrate the good charge transport efficiency in lipids in contrast to the poor efficiency in water. The protein charge transport also exhibits a very strong anisotropic effect in lipids. The peptide secondary structure effect of charge transfer in membranes is analyzed in contrast to that in water. These results suggest that this model can be useful for the prediction of charge transfer efficiency in various environments of interest and indicate that the charge transfer is highly efficient in membrane proteins.
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Affiliation(s)
- Sheh-Yi Sheu
- Department of Life Sciences and Institute of Genome Sciences, and Institute of Biomedical Informatics, National Yang-Ming University, Taipei 112, Taiwan.
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18
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Affiliation(s)
- Bernhard E Flucher
- Section of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria
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19
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Phosphoinositides in Ca(2+) signaling and excitation-contraction coupling in skeletal muscle: an old player and newcomers. J Muscle Res Cell Motil 2015; 36:491-9. [PMID: 26377756 DOI: 10.1007/s10974-015-9422-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 09/09/2015] [Indexed: 10/23/2022]
Abstract
Since the postulate, 30 years ago, that phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P 2) as the precursor of inositol 1,4,5-trisphosphate (Ins(1,4,5)P 3) would be critical for skeletal muscle excitation-contraction (EC) coupling, the issue of whether phosphoinositides (PtdInsPs) may have something to do with Ca(2+) signaling in muscle raised limited interest, if any. In recent years however, the PtdInsP world has expanded considerably with new functions for PtdIns(4,5)P 2 but also with functions for the other members of the PtdInsP family. In this context, the discovery that genetic deficiency in a PtdInsP phosphatase has dramatic consequences on Ca(2+) homeostasis in skeletal muscle came unanticipated and opened up new perspectives in regards to how PtdInsPs modulate muscle Ca(2+) signaling under normal and disease conditions. This review intends to make an update of the established, the questioned, and the unknown regarding the role of PtdInsPs in skeletal muscle Ca(2+) homeostasis and EC coupling, with very specific emphasis given to Ca(2+) signals in differentiated skeletal muscle fibers.
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20
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Berthier C, Kutchukian C, Bouvard C, Okamura Y, Jacquemond V. Depression of voltage-activated Ca2+ release in skeletal muscle by activation of a voltage-sensing phosphatase. J Gen Physiol 2015; 145:315-30. [PMID: 25825170 PMCID: PMC4380211 DOI: 10.1085/jgp.201411309] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 03/05/2015] [Indexed: 12/30/2022] Open
Abstract
Phosphoinositides act as signaling molecules in numerous cellular transduction processes, and phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) regulates the function of several types of plasma membrane ion channels. We investigated the potential role of PtdIns(4,5)P2 in Ca(2+) homeostasis and excitation-contraction (E-C) coupling of mouse muscle fibers using in vivo expression of the voltage-sensing phosphatases (VSPs) Ciona intestinalis VSP (Ci-VSP) or Danio rerio VSP (Dr-VSP). Confocal images of enhanced green fluorescent protein-tagged Dr-VSP revealed a banded pattern consistent with VSP localization within the transverse tubule membrane. Rhod-2 Ca(2+) transients generated by 0.5-s-long voltage-clamp depolarizing pulses sufficient to elicit Ca(2+) release from the sarcoplasmic reticulum (SR) but below the range at which VSPs are activated were unaffected by the presence of the VSPs. However, in Ci-VSP-expressing fibers challenged by 5-s-long depolarizing pulses, the Ca(2+) level late in the pulse (3 s after initiation) was significantly lower at 120 mV than at 20 mV. Furthermore, Ci-VSP-expressing fibers showed a reversible depression of Ca(2+) release during trains, with the peak Ca(2+) transient being reduced by ∼30% after the application of 10 200-ms-long pulses to 100 mV. A similar depression was observed in Dr-VSP-expressing fibers. Cav1.1 Ca(2+) channel-mediated current was unaffected by Ci-VSP activation. In fibers expressing Ci-VSP and a pleckstrin homology domain fused with monomeric red fluorescent protein (PLCδ1PH-mRFP), depolarizing pulses elicited transient changes in mRFP fluorescence consistent with release of transverse tubule-bound PLCδ1PH domain into the cytosol; the voltage sensitivity of these changes was consistent with that of Ci-VSP activation, and recovery occurred with a time constant in the 10-s range. Our results indicate that the PtdIns(4,5)P2 level is tightly maintained in the transverse tubule membrane of the muscle fibers, and that VSP-induced depletion of PtdIns(4,5)P2 impairs voltage-activated Ca(2+) release from the SR. Because Ca(2+) release is thought to be independent from InsP3 signaling, the effect likely results from an interaction between PtdIns(4,5)P2 and a protein partner of the E-C coupling machinery.
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Affiliation(s)
- Christine Berthier
- Centre National de la Recherche Scientifique UMR 5534, Université Lyon 1, Centre de Génétique et de Physiologie Moléculaire et Cellulaire, 69100 Villeurbanne, France
| | - Candice Kutchukian
- Centre National de la Recherche Scientifique UMR 5534, Université Lyon 1, Centre de Génétique et de Physiologie Moléculaire et Cellulaire, 69100 Villeurbanne, France
| | - Clément Bouvard
- Centre National de la Recherche Scientifique UMR 5534, Université Lyon 1, Centre de Génétique et de Physiologie Moléculaire et Cellulaire, 69100 Villeurbanne, France
| | - Yasushi Okamura
- Laboratory of Integrative Physiology, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Vincent Jacquemond
- Centre National de la Recherche Scientifique UMR 5534, Université Lyon 1, Centre de Génétique et de Physiologie Moléculaire et Cellulaire, 69100 Villeurbanne, France
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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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Zhang M, Zhao J, Yang H, Liu P, Bu Y. 310-Helical Peptide Acting as a Dual Relay for Charge-Hopping Transfer in Proteins. J Phys Chem B 2013; 117:6385-93. [DOI: 10.1021/jp4012526] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Meng Zhang
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, PR China
| | - Jing Zhao
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, PR China
| | - Hongfang Yang
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, PR China
| | - Ping Liu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, PR China
| | - Yuxiang Bu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, PR China
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Evolving concepts on the age-related changes in "muscle quality". J Cachexia Sarcopenia Muscle 2012; 3:95-109. [PMID: 22476917 PMCID: PMC3374023 DOI: 10.1007/s13539-011-0054-2] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 12/26/2011] [Indexed: 01/06/2023] Open
Abstract
The deterioration of skeletal muscle with advancing age has long been anecdotally recognized and has been of scientific interest for more than 150 years. Over the past several decades, the scientific and medical communities have recognized that skeletal muscle dysfunction (e.g., muscle weakness, poor muscle coordination, etc.) is a debilitating and life-threatening condition in the elderly. For example, the age-associated loss of muscle strength is highly associated with both mortality and physical disability. It is well-accepted that voluntary muscle force production is not solely dependent upon muscle size, but rather results from a combination of neurologic and skeletal muscle factors, and that biologic properties of both of these systems are altered with aging. Accordingly, numerous scientists and clinicians have used the term "muscle quality" to describe the relationship between voluntary muscle strength and muscle size. In this review article, we discuss the age-associated changes in the neuromuscular system-starting at the level of the brain and proceeding down to the subcellular level of individual muscle fibers-that are potentially influential in the etiology of dynapenia (age-related loss of muscle strength and power).
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Li W, Zhang Z, Yang H, Wu X, Liu J, Bu Y. Trapping of excess electrons at the microhydrated protonated amino groups in proteins. J Chem Phys 2012; 136:105101. [DOI: 10.1063/1.3685606] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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25
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Dystrobrevin controls neurotransmitter release and muscle Ca(2+) transients by localizing BK channels in Caenorhabditis elegans. J Neurosci 2012; 31:17338-47. [PMID: 22131396 DOI: 10.1523/jneurosci.3638-11.2011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Dystrobrevin is a major component of a dystrophin-associated protein complex. It is widely expressed in mammalian tissues, including the nervous system, in which it is localized to the presynaptic nerve terminal with unknown function. In a genetic screen for suppressors of a lethargic phenotype caused by a gain-of-function isoform of SLO-1 in Caenorhabditis elegans, we isolated multiple loss-of-function (lf) mutants of the dystrobrevin gene dyb-1.dyb-1(lf) phenocopied slo-1(lf), causing increased neurotransmitter release at the neuromuscular junction, increased frequency of Ca(2+) transients in body-wall muscle, and abnormal locomotion behavior. Neuron- and muscle-specific rescue experiments suggest that DYB-1 is required for SLO-1 function in both neurons and muscle cells. DYB-1 colocalized with SLO-1 at presynaptic sites in neurons and dense body regions in muscle cells, and dyb-1(lf) caused SLO-1 mislocalization in both types of cells without altering SLO-1 protein level. The neuronal phenotypes of dyb-1(lf) were partially rescued by mouse α-dystrobrevin-1. These observations revealed novel functions of the BK channel in regulating muscle Ca(2+) transients and of dystrobrevin in controlling neurotransmitter release and muscle Ca(2+) transients by localizing the BK channel.
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Lacava C, Sgaragli G, Fusi F. 3,5-Di-t-Butylcatechol as a Ryanodine Receptor Agonist in Rat Intact Skeletal Muscle Fibers. Drug Dev Res 2012. [DOI: 10.1002/ddr.21003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Caterina Lacava
- Dipartimento di Neuroscienze; Università degli Studi di Siena; Siena; Italy
| | | | - Fabio Fusi
- Dipartimento di Neuroscienze; Università degli Studi di Siena; Siena; Italy
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27
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Golini L, Chouabe C, Berthier C, Cusimano V, Fornaro M, Bonvallet R, Formoso L, Giacomello E, Jacquemond V, Sorrentino V. Junctophilin 1 and 2 proteins interact with the L-type Ca2+ channel dihydropyridine receptors (DHPRs) in skeletal muscle. J Biol Chem 2011; 286:43717-43725. [PMID: 22020936 DOI: 10.1074/jbc.m111.292755] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Junctophilins (JPs) anchor the endo/sarcoplasmic reticulum to the plasma membrane, thus contributing to the assembly of junctional membrane complexes in striated muscles and neurons. Recent studies have shown that JPs may be also involved in regulating Ca2+ homeostasis. Here, we report that in skeletal muscle, JP1 and JP2 are part of a complex that, in addition to ryanodine receptor 1 (RyR1), includes caveolin 3 and the dihydropyridine receptor (DHPR). The interaction between JPs and DHPR was mediated by a region encompassing amino acids 230-369 and amino acids 216-399 in JP1 and JP2, respectively. Immunofluorescence studies revealed that the pattern of DHPR and RyR signals in C2C12 cells knocked down for JP1 and JP2 was rather diffused and characterized by smaller puncta in contrast to that observed in control cells. Functional experiments revealed that down-regulation of JPs in differentiated C2C12 cells resulted in a reduction of intramembrane charge movement and the L-type Ca2+ current accompanied by a reduced number of DHPRs at the plasma membrane, whereas there was no substantial alteration in Ca2+ release from the sterol regulatory element-binding protein. Altogether, these results suggest that JP1 and JP2 can facilitate the assembly of DHPR with other proteins of the excitation-contraction coupling machinery.
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Affiliation(s)
- Lucia Golini
- Molecular Medicine Section, Department of Neuroscience, and Interuniversity Institute of Myology, University of Siena, 53100 Siena, Italy
| | - Christophe Chouabe
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, Université Lyon 1, UMR CNRS 5534, 69622 Villeurbanne cedex, France
| | - Christine Berthier
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, Université Lyon 1, UMR CNRS 5534, 69622 Villeurbanne cedex, France
| | - Vincenza Cusimano
- Molecular Medicine Section, Department of Neuroscience, and Interuniversity Institute of Myology, University of Siena, 53100 Siena, Italy
| | - Mara Fornaro
- Molecular Medicine Section, Department of Neuroscience, and Interuniversity Institute of Myology, University of Siena, 53100 Siena, Italy
| | - Robert Bonvallet
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, Université Lyon 1, UMR CNRS 5534, 69622 Villeurbanne cedex, France
| | - Luca Formoso
- Molecular Medicine Section, Department of Neuroscience, and Interuniversity Institute of Myology, University of Siena, 53100 Siena, Italy
| | - Emiliana Giacomello
- Molecular Medicine Section, Department of Neuroscience, and Interuniversity Institute of Myology, University of Siena, 53100 Siena, Italy
| | - Vincent Jacquemond
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, Université Lyon 1, UMR CNRS 5534, 69622 Villeurbanne cedex, France
| | - Vincenzo Sorrentino
- Molecular Medicine Section, Department of Neuroscience, and Interuniversity Institute of Myology, University of Siena, 53100 Siena, Italy.
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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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Stiber JA, Rosenberg PB. The role of store-operated calcium influx in skeletal muscle signaling. Cell Calcium 2010; 49:341-9. [PMID: 21176846 DOI: 10.1016/j.ceca.2010.11.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 11/29/2010] [Indexed: 11/29/2022]
Abstract
In cardiac and skeletal muscle Ca(2+) release from intracellular stores triggers actomyosin cross-bridge formation and the generation of contractile force. In the face of large fluctuations of intracellular calcium ([Ca(2+)](i)) that occur with contractile activity, myocytes are able to sense and respond to changes in workload and patterns of activation through calcium signaling pathways which modulate gene expression and cellular metabolism. Store-operated calcium influx has emerged as a mechanism by which calcium signaling pathways are activated in order to respond to the changing demands of the myocyte. Abnormalities of store-operated calcium influx may contribute to maladaptive muscle remodeling in multiple disease states. The importance of store-operated calcium influx in muscle is confirmed in mice lacking STIM1 which die perinatally and in patients with mutations on STIM1 or Orai1 who exhibit a myopathy exhibited by hypotonia. In this review, we consider the role of store-operated Ca(2+) entry into skeletal muscle as a critical mediator of Ca(2+) dependent gene expression and how alterations in Ca(2+) influx may influence muscle development and disease.
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Affiliation(s)
- Jonathan A Stiber
- Department of Medicine, Duke University Medical Center, Durham, NC 27710, United States
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30
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Quiñonez M, González F, Morgado-Valle C, DiFranco M. Effects of membrane depolarization and changes in extracellular [K(+)] on the Ca (2+) transients of fast skeletal muscle fibers. Implications for muscle fatigue. J Muscle Res Cell Motil 2010; 31:13-33. [PMID: 20049631 PMCID: PMC2908756 DOI: 10.1007/s10974-009-9195-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 12/11/2009] [Indexed: 12/02/2022]
Abstract
Repetitive activation of skeletal muscle fibers leads to a reduced transmembrane K+ gradient. The resulting membrane depolarization has been proposed to play a major role in the onset of muscle fatigue. Nevertheless, raising the extracellular K+ (\documentclass[12pt]{minimal}
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\begin{document}$$ [ {\text{K}}^{ + } ]_{\text{o}} $$\end{document}) to 10 mM potentiates twitch force of rested amphibian and mammalian fibers. We used a double Vaseline gap method to simultaneously record action potentials (AP) and Ca2+ transients from rested frog fibers activated by single and tetanic stimulation (10 pulses, 100 Hz) at various \documentclass[12pt]{minimal}
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\begin{document}$$ [ {\text{K}}^{ + } ]_{\text{o}} $$\end{document} and membrane potentials. Depolarization resulting from current injection or raised \documentclass[12pt]{minimal}
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\begin{document}$$ [ {\text{K}}^{ + } ]_{\text{o}} $$\end{document} produced an increase in the resting [Ca2+]. Ca2+ transients elicited by single stimulation were potentiated by depolarization from −80 to −60 mV but markedly depressed by further depolarization. Potentiation was inversely correlated with a reduction in the amplitude, overshoot and duration of APs. Similar effects were found for the Ca2+ transients elicited by the first pulse of 100 Hz trains. Depression or block of Ca2+ transient in response to the 2nd to 10th pulses of 100 Hz trains was observed at smaller depolarizations as compared to that seen when using single stimulation. Changes in Ca2+ transients along the trains were associated with impaired or abortive APs. Raising \documentclass[12pt]{minimal}
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\begin{document}$$ [ {\text{K}}^{ + } ]_{\text{o}} $$\end{document} to 10 mM potentiated Ca2+ transients elicited by single and tetanic stimulation, while raising \documentclass[12pt]{minimal}
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\begin{document}$$ [ {\text{K}}^{ + } ]_{\text{o}} $$\end{document} to 15 mM markedly depressed both responses. The effects of 10 mM \documentclass[12pt]{minimal}
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\begin{document}$$ {\text{K}}_{\text{o}}^{ + } $$\end{document} on Ca2+ transients, but not those of 15 mM \documentclass[12pt]{minimal}
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\begin{document}$$ {\text{K}}_{\text{o}}^{ + } $$\end{document}, could be fully reversed by hyperpolarization. The results suggests that the force potentiating effects of 10 mM \documentclass[12pt]{minimal}
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\begin{document}$$ {\text{K}}_{\text{o}}^{ + } $$\end{document} might be mediated by depolarization dependent changes in resting [Ca2+] and Ca2+ release, and that additional mechanisms might be involved in the effects of 15 mM \documentclass[12pt]{minimal}
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\begin{document}$$ {\text{K}}_{\text{o}}^{ + } $$\end{document} on force generation.
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Affiliation(s)
- Marbella Quiñonez
- Laboratorio de Fisiología y Biofisíca del Músculo, IBE, UCV, Caracas, Venezuela.
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31
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Dai S, Hall DD, Hell JW. Supramolecular assemblies and localized regulation of voltage-gated ion channels. Physiol Rev 2009; 89:411-52. [PMID: 19342611 DOI: 10.1152/physrev.00029.2007] [Citation(s) in RCA: 264] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
This review addresses the localized regulation of voltage-gated ion channels by phosphorylation. Comprehensive data on channel regulation by associated protein kinases, phosphatases, and related regulatory proteins are mainly available for voltage-gated Ca2+ channels, which form the main focus of this review. Other voltage-gated ion channels and especially Kv7.1-3 (KCNQ1-3), the large- and small-conductance Ca2+-activated K+ channels BK and SK2, and the inward-rectifying K+ channels Kir3 have also been studied to quite some extent and will be included. Regulation of the L-type Ca2+ channel Cav1.2 by PKA has been studied most thoroughly as it underlies the cardiac fight-or-flight response. A prototypical Cav1.2 signaling complex containing the beta2 adrenergic receptor, the heterotrimeric G protein Gs, adenylyl cyclase, and PKA has been identified that supports highly localized via cAMP. The type 2 ryanodine receptor as well as AMPA- and NMDA-type glutamate receptors are in close proximity to Cav1.2 in cardiomyocytes and neurons, respectively, yet independently anchor PKA, CaMKII, and the serine/threonine phosphatases PP1, PP2A, and PP2B, as is discussed in detail. Descriptions of the structural and functional aspects of the interactions of PKA, PKC, CaMKII, Src, and various phosphatases with Cav1.2 will include comparisons with analogous interactions with other channels such as the ryanodine receptor or ionotropic glutamate receptors. Regulation of Na+ and K+ channel phosphorylation complexes will be discussed in separate papers. This review is thus intended for readers interested in ion channel regulation or in localization of kinases, phosphatases, and their upstream regulators.
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Affiliation(s)
- Shuiping Dai
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242-1109, USA
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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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33
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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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34
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Schlag EW, Sheu SY, Yang DY, Selzle HL, Lin SH. Distal charge transport in peptides. Angew Chem Int Ed Engl 2007; 46:3196-210. [PMID: 17372995 DOI: 10.1002/anie.200601623] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Biological systems often transport charges and reactive processes over substantial distances. Traditional models of chemical kinetics generally do not describe such extreme distal processes. In this Review, an atomistic model for a distal transport of information, which was specifically developed for peptides, is considered. Chemical reactivity is taken as the result of distal effects based on two-step bifunctional kinetics involving unique, very rapid motional properties of peptides in the subpicosecond regime. The bifunctional model suggests highly efficient transport of charge and reactivity in an isolated peptide over a substantial distance; conversely, a very low efficiency in a water environment was found. The model suggests ultrafast transport of charge and reactivity over substantial molecular distances in a peptide environment. Many such domains can be active in a protein.
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Affiliation(s)
- Edward W Schlag
- Institut für Physikalische und Theoretische Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany.
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35
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Schlag E, Sheu SY, Yang DY, Selzle H, Lin S. Distaler Ladungstransport in Peptiden. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200601623] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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36
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Csernoch L. Sparks and embers of skeletal muscle: the exciting events of contractile activation. Pflugers Arch 2007; 454:869-78. [PMID: 17342530 DOI: 10.1007/s00424-007-0244-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Accepted: 02/21/2007] [Indexed: 11/26/2022]
Abstract
Intracellular calcium concentration ([Ca(2+)](i)) is a key player in a wide range of cellular functions from long-term effects that determine the fate of the cell to immediate responses as secretion and motility. To initiate contraction, calcium ions in skeletal muscle are released into the myoplasm through the calcium channels, the ryanodine receptors, of the sarcoplasmic reticulum. The opening of these channels give rise to localised increases in [Ca(2+)](i), originally termed calcium sparks, that fuse and generate the global calcium transient. Whereas calcium sparks in amphibians are abundant and stereotyped, events in mammalian skeletal muscle are scarce and morphologically diverse. This review compares the different forms of calcium release events, occurring spontaneously or evoked by a depolarising pulse, observed in the different classes of vertebrates. It then addresses the questions whether or not these events can be considered as elementary and how the global calcium transient can be reconstructed from them.
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Affiliation(s)
- László Csernoch
- Department of Physiology, RCMM, MHSC, University of Debrecen, P.O. Box 22, Debrecen, 4012, Hungary.
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37
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Copello JA, Zima AV, Diaz-Sylvester PL, Fill M, Blatter LA. Ca2+ entry-independent effects of L-type Ca2+ channel modulators on Ca2+ sparks in ventricular myocytes. Am J Physiol Cell Physiol 2007; 292:C2129-40. [PMID: 17314267 PMCID: PMC2094215 DOI: 10.1152/ajpcell.00437.2006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During the cardiac action potential, Ca(2+) entry through dyhidropyridine receptor L-type Ca(2+) channels (DHPRs) activates ryanodine receptors (RyRs) Ca(2+)-release channels, resulting in massive Ca(2+) mobilization from the sarcoplasmic reticulum (SR). This global Ca(2+) release arises from spatiotemporal summation of many localized elementary Ca(2+)-release events, Ca(2+) sparks. We tested whether DHPRs modulate Ca(2+)sparks in a Ca(2+) entry-independent manner. Negative modulation by DHPR of RyRs via physical interactions is accepted in resting skeletal muscle but remains controversial in the heart. Ca(2+) sparks were studied in cat cardiac myocytes permeabilized with saponin or internally perfused via a patch pipette. Bathing and pipette solutions contained low Ca(2+) (100 nM). Under these conditions, Ca(2+) sparks were detected with a stable frequency of 3-5 sparks.s(-1).100 microm(-1). The DHPR blockers nifedipine, nimodipine, FS-2, and calciseptine decreased spark frequency, whereas the DHPR agonists Bay-K8644 and FPL-64176 increased it. None of these agents altered the spatiotemporal characteristics of Ca(2+) sparks. The DHPR modulators were also without effect on SR Ca(2+) load (caffeine-induced Ca(2+) transients) or sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) activity (Ca(2+) loading rates of isolated SR microsomes) and did not change cardiac RyR channel gating (planar lipid bilayer experiments). In summary, DHPR modulators affected spark frequency in the absence of DHPR-mediated Ca(2+) entry. This action could not be attributed to a direct action of DHPR modulators on SERCA or RyRs. Our results suggest that the activity of RyR Ca(2+)-release units in ventricular myocytes is modulated by Ca(2+) entry-independent conformational changes in neighboring DHPRs.
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Affiliation(s)
- Julio A Copello
- Dept. of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL 62794-9629, USA.
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38
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Nasledov GA, Katina IE, Zhitnikova YV. Changes in the functioning of the electromechanical connection during tetanic contraction. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2007; 37:153-9. [PMID: 17187207 DOI: 10.1007/s11055-007-0163-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Indexed: 11/26/2022]
Abstract
The functioning of the electromechanical connection during tetanic contraction in frog skeletal muscle was studied. Analysis using caffeine, calcium-free medium, the ryanodine receptor blocker dantrolene, and the Ca-ATPase inhibitor thapsigargin showed that the initial increase in tetanus, as in twitch contractions, did not require the presence of calcium ions in the surrounding medium, which is in agreement with published data. Contraction was accompanied by activation of potential-dependent release of calcium from the sarcoplasmic reticulum. In contrast, the secondary rise phase and/or the duration of the tetanus plateau were critically dependent on the present of Ca2+ in the surrounding medium. Given that contraction in this situation was inhibited by dantrolene, activation of prolonged contraction was also mediated by calcium released from the sarcoplasmic reticulum, though ryanodine receptors were now activated not by changes in the membrane potential but by the influx of external calcium. Thus, external calcium plays a significant role in the formation of prolonged contractile responses, providing for longer-lasting maintenance of power in contracted muscles.
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Affiliation(s)
- G A Nasledov
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 44 M. Torez Prospekt, 194223, St. Petersburg, Russia
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Seo IR, Moh S, Lee E, Meissner G, Kim D. Aldolase potentiates DIDS activation of the ryanodine receptor in rabbit skeletal sarcoplasmic reticulum. Biochem J 2006; 399:325-33. [PMID: 16817780 PMCID: PMC1609923 DOI: 10.1042/bj20060701] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
DIDS (4,4'-di-isothiocyanostilbene-2,2'-disulfonate), an anion channel blocker, triggers Ca2+ release from skeletal muscle SR (sarcoplasmic reticulum). The present study characterized the effects of DIDS on rabbit skeletal single Ca2+-release channel/RyR1 (ryanodine receptor type 1) incorporated into a planar lipid bilayer. When junctional SR vesicles were used for channel incorporation (native RyR1), DIDS increased the mean P(o) (open probability) of RyR1 without affecting unitary conductance when Cs+ was used as the charge carrier. Lifetime analysis of single RyR1 activities showed that 10 microM DIDS induced reversible long-lived open events (P(o)=0.451+/-0.038) in the presence of 10 microM Ca2+, due mainly to a new third component for both open and closed time constants. However, when purified RyR1 was examined in the same condition, 10 microM DIDS became considerably less potent (P(o)=0.206+/-0.025), although the caffeine response was similar between native and purified RyR1. Hence we postulated that a DIDS-binding protein, essential for the DIDS sensitivity of RyR1, was lost during RyR1 purification. DIDS-affinity column chromatography of solubilized junctional SR, and MALDI-TOF (matrix-assisted laser-desorption ionization-time-of-flight) MS analysis of the affinity-column-associated proteins, identified four major DIDS-binding proteins in the SR fraction. Among them, aldolase was the only protein that greatly potentiated DIDS sensitivity. The association between RyR1 and aldolase was further confirmed by co-immunoprecipitation and aldolase-affinity batch-column chromatography. Taken together, we conclude that aldolase is physically associated with RyR1 and could confer a considerable potentiation of the DIDS effect on RyR1.
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Affiliation(s)
- In-Ra Seo
- *Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Korea
| | - Sang Hyun Moh
- *Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Korea
| | - Eun Hui Lee
- †Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Gerhard Meissner
- ‡Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, U.S.A
| | - Do Han Kim
- *Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Korea
- To whom correspondence should be addressed (email )
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Weisleder N, Brotto M, Komazaki S, Pan Z, Zhao X, Nosek T, Parness J, Takeshima H, Ma J. Muscle aging is associated with compromised Ca2+ spark signaling and segregated intracellular Ca2+ release. ACTA ACUST UNITED AC 2006; 174:639-45. [PMID: 16943181 PMCID: PMC2064307 DOI: 10.1083/jcb.200604166] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Reduced homeostatic capacity for intracellular Ca2+ ([Ca2+]i) movement may underlie the progression of sarcopenia and contractile dysfunction during muscle aging. We report two alterations to Ca2+ homeostasis in skeletal muscle that are associated with aging. Ca2+ sparks, which are the elemental units of Ca2+ release from sarcoplasmic reticulum, are silent under resting conditions in young muscle, yet activate in a dynamic manner upon deformation of membrane structures. The dynamic nature of Ca2+ sparks appears to be lost in aged skeletal muscle. Using repetitive voltage stimulation on isolated muscle preparations, we identify a segregated [Ca2+]i reserve that uncouples from the normal excitation-contraction process in aged skeletal muscle. Similar phenotypes are observed in adolescent muscle null for a synaptophysin-family protein named mitsugumin-29 (MG29) that is involved in maintenance of muscle membrane ultrastructure and Ca2+ signaling. This finding, coupled with decreased expression of MG29 in aged skeletal muscle, suggests that MG29 expression is important in maintaining skeletal muscle Ca2+ homeostasis during aging.
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Affiliation(s)
- Noah Weisleder
- Department of Physiology and Biophysics, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
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Katina IE, Nasledov GA. Influence of ryanodine receptor agonist and antagonist on development of potassium contracture in phasic (twitch) and tonic fibers of frog skeletal muscle. Biophysics (Nagoya-shi) 2006. [DOI: 10.1134/s0006350906050216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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42
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Sobol KV, Belostotskaya GB, Nesterov VP, Nasledov GA. Adrenergic and cholinergic activation of calcium signals in cultured postnatal skeletal myocytes of the rat. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2006; 406:27-31. [PMID: 16572806 DOI: 10.1134/s001249660601008x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- K V Sobol
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, pr. Morisa Toreza 44, St. Petersburg, 194223 Russia
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43
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Livneh A, Cohen R, Atlas D. A novel molecular inactivation determinant of voltage-gated CaV1.2 L-type Ca2+ channel. Neuroscience 2006; 139:1275-87. [PMID: 16533566 DOI: 10.1016/j.neuroscience.2006.01.028] [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: 07/07/2005] [Revised: 01/26/2006] [Accepted: 01/26/2006] [Indexed: 11/16/2022]
Abstract
The inactivation of voltage-gated L-type Ca(2+) channels (Ca(V)1) regulates Ca(2+) entry and controls intracellular Ca(2+) levels that are essential for cellular activity. The molecular entities implicated in L-channel (Ca(V)1.2) inactivation are not fully identified. Here we show for the first time the functional impact of one of the two highly conserved clusters of six negatively charged glutamates and aspartate (802-807; poly ED motif) at the II-III loop of the alpha 1 subunits of rabbit of Ca(v)1.2, alpha(1)1.2 and alpha(1)1.2 DeltaN60-Delta1733) on voltage-dependent inactivation. Mutation of the poly ED motif to alanine or glutamine/asparagine greatly enhanced voltage-dependent inactivation, shifting the voltage dependence to negative potentials by >50 mV and conferring a neuronal like inactivation kinetics onto Ca(V)1.2. The large shift in the midpoint of inactivation of the steady-state inactivation kinetics was observed also in Ca(2+) or Ba(2+) and was not altered by the beta2A subunit. Missing from the fast inactivating neuronal P/Q (Ca(V)2.1)-, N (Ca(V)2.2)- or R (Ca(V)2.3)-type channels and modulating Ca(V)1.2 inactivation kinetics, the poly ED motif is likely to be a specific L-type Ca(2+) channels inactivating domain. Our results fit a model in which the poly ED either by itself or as part of a larger inactivating motif acts as Ca(V)1.2 specific built-in "stopper." In this model, Ca(V)1 accomplishes a large Ca(2+) influx during depolarization, possibly by the poly ED hindering occlusion at the pore. Furthermore, the selective designed poly ED perhaps clarifies major inactivation differences between L- and non-L-type calcium channels.
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Affiliation(s)
- A Livneh
- Department of Biological Chemistry, The Silverman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
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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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Kobayashi S, Yamamoto T, Parness J, Ikemoto N. Antibody probe study of Ca2+ channel regulation by interdomain interaction within the ryanodine receptor. Biochem J 2004; 380:561-9. [PMID: 15027895 PMCID: PMC1224195 DOI: 10.1042/bj20040112] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2004] [Revised: 02/26/2004] [Accepted: 03/18/2004] [Indexed: 11/17/2022]
Abstract
N-terminal and central domains of ryanodine receptor 1 (RyR1), where many reported malignant hyperthermia (MH) mutations are localized, represent putative channel regulatory domains. Recent domain peptide (DP) probe studies led us to the hypothesis that these domains interact to stabilize the closed state of channel (zipping), while weakening of domain-domain interactions (unzipping) by mutation de-stabilizes the channel, making it leaky to Ca2+ or sensitive to the agonists of RyR1. As shown previously, DP1 (N-terminal domain peptide) and DP4 (central domain peptide) produced MH-like channel activation/sensitization effects, presumably by peptide binding to sites critical to stabilizing domain-domain interactions and resultant loss of conformational constraints. Here we report that polyclonal anti-DP1 and anti-DP4 antibodies also produce MH-like channel activation and sensitization effects as evidenced by about 4-fold enhancement of high affinity [3H]ryanodine binding to RyR1 and by a significant left-shift of the concentration-dependence of activation of sarcoplasmic reticulum Ca2+ release by polylysine. Fluorescence quenching experiments demonstrate that the accessibility of a DP4-directed, conformationally sensitive fluorescence probe linked to the RyR1 N-terminal domain is increased in the presence of domain-specific antibodies, consistent with the view that these antibodies produce unzipping of interacting domains that are of hindered accessibility to the surrounding aqueous environment. Our results suggest that domain-specific antibody binding induces a conformational change resulting in channel activation, and are consistent with the hypothesis that interacting N-terminal and central domains are intimately involved in the regulation of RyR1 channel function.
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46
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Lee EH, Rho SH, Kwon SJ, Eom SH, Allen PD, Kim DH. N-terminal region of FKBP12 is essential for binding to the skeletal ryanodine receptor. J Biol Chem 2004; 279:26481-8. [PMID: 15033987 DOI: 10.1074/jbc.m309574200] [Citation(s) in RCA: 34] [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
It is known that the two types of FK506-binding proteins FKBP12 and FKBP12.6 are tightly associated with the skeletal (RyR1) and cardiac ryanodine receptors (RyR2), respectively, and their interactions are important for channel functions of the RyR. In the case of cardiac muscle, three amino acid residues (Gln-31, Asn-32, and Phe-59) of FKBP12.6 could be essential for the selective binding to RyR2 (Xin, H. B., Rogers, K., Qi, Y., Kanematsu, T., and Fleischer, S. (1999) J. Biol. Chem. 274, 15315-15319). In this study to identify amino acid residues of FKBP12 that are important for the selective binding to RyR1, we mutated 9 amino acid residues of FKBP12 that differ from the counterparts of FKBP12.6 (Q3E, R18A, E31Q, D32N, M49R, R57A, W59F, H94A, and K105A), and we examined binding properties of these mutants to RyR1 by in vitro binding assay by using glutathione S-transferase-fused proteins of the mutants and Triton X-100-solubilized, FKBP12-depleted rabbit skeletal sarcoplasmic reticulum vesicles. Among the nine mutants tested, only Q3E and R18A lost their selective binding ability to RyR1. Furthermore, co-immunoprecipitation of RyR1 with 33 various mutants for the 9 positions produced by introducing different size, charge, and hydrophobicity revealed that an integration of the hydrogen bonds by the irreplaceable Gln-3 and the hydrophobic interactions by the residues Arg-18 and Met-49 could be a possible mechanism for the binding of FKBP12 to RyR1. Therefore, these results suggest that the N-terminal regions of FKBP12 (Gln-3 and Arg-18) and Met-49 are essential and unique for binding of FKBP12 to RyR1 in skeletal muscle.
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Affiliation(s)
- Eun Hui Lee
- Department of Life Science, Kwangju Institute of Science and Technology, Gwangju 500-712 Korea
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Marobbio CMT, Agrimi G, Lasorsa FM, Palmieri F. Identification and functional reconstitution of yeast mitochondrial carrier for S-adenosylmethionine. EMBO J 2004; 22:5975-82. [PMID: 14609944 PMCID: PMC275433 DOI: 10.1093/emboj/cdg574] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The genome of Saccharomyces cerevisiae contains 35 members of the mitochondrial carrier protein family, most of which have not yet been functionally identified. Here the identification of the mitochondrial carrier for S-adenosylmethionine (SAM) Sam5p is described. The corresponding gene has been overexpressed in bacteria and the protein has been reconstituted into phospholipid vesicles and identified by its transport properties. In confirmation of its identity, (i) the Sam5p-GFP protein was found to be targeted to mitochondria; (ii) the cells lacking the gene for this carrier showed auxotrophy for biotin (which is synthesized in the mitochondria by the SAM-requiring Bio2p) on fermentable carbon sources and a petite phenotype on non-fermentable substrates; and (iii) both phenotypes of the knock-out mutant were overcome by expressing the cytosolic SAM synthetase (Sam1p) inside the mitochondria.
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Affiliation(s)
- C M T Marobbio
- Department of Pharmaco-Biology, Laboratory of Biochemistry and Molecular Biology, University of Bari, Bari, Italy
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48
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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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Tada T, Ohmori M, Iida H. Molecular dissection of the hydrophobic segments H3 and H4 of the yeast Ca2+ channel component Mid1. J Biol Chem 2003; 278:9647-54. [PMID: 12514173 DOI: 10.1074/jbc.m206993200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Saccharomyces cerevisiae MID1 gene product, Mid1, is composed of 548 amino acid residues, has four relatively hydrophobic segments named H1-H4, and functions as a Ca(2+)-permeable, stretch-activated channel when expressed in mammalian cells. In some conditions Mid1 cooperates with Cch1, a yeast homolog of the alpha1 subunit of mammalian voltage-gated channels. To identify the important regions or amino acid residues necessary for Mid1 function, we employed in vitro site-directed mutagenesis on H3 and H4 of Mid1 and expressed the resulting mutant genes in a mid1 null mutant to examine whether the mutant gene products are functional or not in vivo. Mutant Mid1 proteins lacking the whole H3 or H4 segment, H3De or H4De, did not complement the lethality and low Ca(2+) accumulation activity of the mid1 mutant, although their localization and contents appeared to be normal, indicating that H3 and H4 are required for Mid1 function itself. Single amino acid exchange experiments on individual amino acid residues of H3 and H4 showed that 10 of 20 residues in H3 and 14 of 23 residues in H4 were important for the normal function of Mid1. In particular, we found four severe loss-of-function mutations, D341E, F356S, C373D, and C373R, and two interesting mutations leading to a high level of Ca(2+) accumulation with a slightly low complementing activity, G342A and Y355A. The importance of these amino acid residues will be discussed.
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Affiliation(s)
- Tomoko Tada
- Department of Biology, Tokyo Gakugei University, Tokyo 184-8501, Japan
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Abstract
The ryanodine receptors (RyRs) are a family of Ca2+ release channels found on intracellular Ca2+ storage/release organelles. The RyR channels are ubiquitously expressed in many types of cells and participate in a variety of important Ca2+ signaling phenomena (neurotransmission, secretion, etc.). In striated muscle, the RyR channels represent the primary pathway for Ca2+ release during the excitation-contraction coupling process. In general, the signals that activate the RyR channels are known (e.g., sarcolemmal Ca2+ influx or depolarization), but the specific mechanisms involved are still being debated. The signals that modulate and/or turn off the RyR channels remain ambiguous and the mechanisms involved unclear. Over the last decade, studies of RyR-mediated Ca2+ release have taken many forms and have steadily advanced our knowledge. This robust field, however, is not without controversial ideas and contradictory results. Controversies surrounding the complex Ca2+ regulation of single RyR channels receive particular attention here. In addition, a large body of information is synthesized into a focused perspective of single RyR channel function. The present status of the single RyR channel field and its likely future directions are also discussed.
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Affiliation(s)
- Michael Fill
- Department of Physiology, Loyola University Chicago, Maywood, Illinois 60153, USA
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