1
|
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.
Collapse
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
| |
Collapse
|
2
|
Rossi D, Catallo MR, Pierantozzi E, Sorrentino V. Mutations in proteins involved in E-C coupling and SOCE and congenital myopathies. J Gen Physiol 2022; 154:213407. [PMID: 35980353 PMCID: PMC9391951 DOI: 10.1085/jgp.202213115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 07/15/2022] [Accepted: 07/21/2022] [Indexed: 11/24/2022] Open
Abstract
In skeletal muscle, Ca2+ necessary for muscle contraction is stored and released from the sarcoplasmic reticulum (SR), a specialized form of endoplasmic reticulum through the mechanism known as excitation–contraction (E-C) coupling. Following activation of skeletal muscle contraction by the E-C coupling mechanism, replenishment of intracellular stores requires reuptake of cytosolic Ca2+ into the SR by the activity of SR Ca2+-ATPases, but also Ca2+ entry from the extracellular space, through a mechanism called store-operated calcium entry (SOCE). The fine orchestration of these processes requires several proteins, including Ca2+ channels, Ca2+ sensors, and Ca2+ buffers, as well as the active involvement of mitochondria. Mutations in genes coding for proteins participating in E-C coupling and SOCE are causative of several myopathies characterized by a wide spectrum of clinical phenotypes, a variety of histological features, and alterations in intracellular Ca2+ balance. This review summarizes current knowledge on these myopathies and discusses available knowledge on the pathogenic mechanisms of disease.
Collapse
Affiliation(s)
- Daniela Rossi
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy.,Interdepartmental Program of Molecular Diagnosis and Pathogenetic Mechanisms of Rare Genetic Diseases, Azienda Ospedaliero Universitaria Senese, Siena, Italy
| | - Maria Rosaria Catallo
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Enrico Pierantozzi
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Vincenzo Sorrentino
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy.,Interdepartmental Program of Molecular Diagnosis and Pathogenetic Mechanisms of Rare Genetic Diseases, Azienda Ospedaliero Universitaria Senese, Siena, Italy
| |
Collapse
|
3
|
O'Connor TN, Kallenbach JG, Orciuoli HM, Paris ND, Bachman JF, Johnston CJ, Hernady E, Williams JP, Dirksen RT, Chakkalakal JV. Endurance exercise attenuates juvenile irradiation-induced skeletal muscle functional decline and mitochondrial stress. Skelet Muscle 2022; 12:8. [PMID: 35414122 PMCID: PMC9004104 DOI: 10.1186/s13395-022-00291-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 04/05/2022] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Radiotherapy is commonly used to treat childhood cancers and can have adverse effects on muscle function, but the underlying mechanisms have yet to be fully elucidated. We hypothesized that endurance exercise following radiation treatment would improve skeletal muscle function. METHODS We utilized the Small Animal Radiation Research Platform (SARRP) to irradiate juvenile male mice with a clinically relevant fractionated dose of 3× (every other day over 5 days) 8.2 Gy X-ray irradiation locally from the knee to footpad region of the right hindlimb. Mice were then singly housed for 1 month in cages equipped with either locked or free-spinning voluntary running wheels. Ex vivo muscle contractile function, RT-qPCR analyses, resting cytosolic and sarcoplasmic reticulum (SR) store Ca2+ levels, mitochondrial reactive oxygen species levels (MitoSOX), and immunohistochemical and biochemical analyses of muscle samples were conducted to assess the muscle pathology and the relative therapeutic impact of voluntary wheel running (VWR). RESULTS Irradiation reduced fast-twitch extensor digitorum longus (EDL) muscle-specific force by 27% compared to that of non-irradiated mice, while VWR post-irradiation improved muscle-specific force by 37%. Radiation treatment similarly reduced slow-twitch soleus muscle-specific force by 14% compared to that of non-irradiated mice, while VWR post-irradiation improved specific force by 18%. We assessed intracellular Ca2+ regulation, oxidative stress, and mitochondrial homeostasis as potential mechanisms of radiation-induced pathology and exercise-mediated rescue. We found a significant reduction in resting cytosolic Ca2+ concentration following irradiation in sedentary mice. Intriguingly, however, SR Ca2+ store content was increased in myofibers from irradiated mice post-VWR compared to mice that remained sedentary. We observed a 73% elevation in the overall protein oxidization in muscle post-irradiation, while VWR reduced protein nitrosylation by 35% and mitochondrial reactive oxygen species (ROS) production by 50%. Finally, we found that VWR significantly increased the expression of PGC1α at both the transcript and protein levels, consistent with an exercise-dependent increase in mitochondrial biogenesis. CONCLUSIONS Juvenile irradiation stunted muscle development, disrupted proper Ca2+ handling, damaged mitochondria, and increased oxidative and nitrosative stress, paralleling significant deficits in muscle force production. Exercise mitigated aberrant Ca2+ handling, mitochondrial homeostasis, and increased oxidative and nitrosative stress in a manner that correlated with improved skeletal muscle function after radiation.
Collapse
Affiliation(s)
- Thomas N O'Connor
- Department of Biomedical Genetics, Genetics, Development and Stem Cells Graduate Program, University of Rochester Medical Center, Rochester, NY, USA
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Jacob G Kallenbach
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
- Department of Biomedical Engineering, University of Rochester Medical Center, Rochester, NY, USA
| | - Haley M Orciuoli
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
- Department of Biology, Biological Sciences, University of Rochester, Rochester, NY, USA
| | - Nicole D Paris
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - John F Bachman
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
- Department of Pathology and Laboratory Medicine, Cell Biology of Disease Graduate Program, University of Rochester Medical Center, Rochester, NY, USA
| | - Carl J Johnston
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
| | - Eric Hernady
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, NY, USA
| | - Jacqueline P Williams
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, NY, USA
| | - Robert T Dirksen
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Joe V Chakkalakal
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA.
- Department of Biomedical Engineering, University of Rochester Medical Center, Rochester, NY, USA.
- Department of Orthopaedic Surgery and Cell Biology, Duke University, Durham, NC, USA.
| |
Collapse
|
4
|
Hanna AD, Lee CS, Babcock L, Wang H, Recio J, Hamilton SL. Pathological mechanisms of vacuolar aggregate myopathy arising from a Casq1 mutation. FASEB J 2021; 35:e21349. [PMID: 33786938 DOI: 10.1096/fj.202001653rr] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 12/15/2020] [Accepted: 12/22/2020] [Indexed: 11/11/2022]
Abstract
Mice with a mutation (D244G, DG) in calsequestrin 1 (CASQ1), analogous to a human mutation in CASQ1 associated with a delayed onset human myopathy (vacuolar aggregate myopathy), display a progressive myopathy characterized by decreased activity, decreased ability of fast twitch muscles to generate force and low body weight after one year of age. The DG mutation causes CASQ1 to partially dissociate from the junctional sarcoplasmic reticulum (SR) and accumulate in the endoplasmic reticulum (ER). Decreased junctional CASQ1 reduces SR Ca2+ release. Muscles from older DG mice display ER stress, ER expansion, increased mTOR signaling, inadequate clearance of aggregated proteins by the proteasomes, and elevation of protein aggregates and lysosomes. This study suggests that the myopathy associated with the D244G mutation in CASQ1 is driven by CASQ1 mislocalization, reduced SR Ca2+ release, CASQ1 misfolding/aggregation and ER stress. The subsequent maladaptive increase in protein synthesis and decreased protein aggregate clearance are likely to contribute to disease progression.
Collapse
Affiliation(s)
- Amy D Hanna
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Chang Seok Lee
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Lyle Babcock
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Hui Wang
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Joseph Recio
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Susan L Hamilton
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| |
Collapse
|
5
|
Michelucci A, Liang C, Protasi F, Dirksen RT. Altered Ca 2+ Handling and Oxidative Stress Underlie Mitochondrial Damage and Skeletal Muscle Dysfunction in Aging and Disease. Metabolites 2021; 11:metabo11070424. [PMID: 34203260 PMCID: PMC8304741 DOI: 10.3390/metabo11070424] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 06/22/2021] [Accepted: 06/24/2021] [Indexed: 12/26/2022] Open
Abstract
Skeletal muscle contraction relies on both high-fidelity calcium (Ca2+) signals and robust capacity for adenosine triphosphate (ATP) generation. Ca2+ release units (CRUs) are highly organized junctions between the terminal cisternae of the sarcoplasmic reticulum (SR) and the transverse tubule (T-tubule). CRUs provide the structural framework for rapid elevations in myoplasmic Ca2+ during excitation-contraction (EC) coupling, the process whereby depolarization of the T-tubule membrane triggers SR Ca2+ release through ryanodine receptor-1 (RyR1) channels. Under conditions of local or global depletion of SR Ca2+ stores, store-operated Ca2+ entry (SOCE) provides an additional source of Ca2+ that originates from the extracellular space. In addition to Ca2+, skeletal muscle also requires ATP to both produce force and to replenish SR Ca2+ stores. Mitochondria are the principal intracellular organelles responsible for ATP production via aerobic respiration. This review provides a broad overview of the literature supporting a role for impaired Ca2+ handling, dysfunctional Ca2+-dependent production of reactive oxygen/nitrogen species (ROS/RNS), and structural/functional alterations in CRUs and mitochondria in the loss of muscle mass, reduction in muscle contractility, and increase in muscle damage in sarcopenia and a wide range of muscle disorders including muscular dystrophy, rhabdomyolysis, central core disease, and disuse atrophy. Understanding the impact of these processes on normal muscle function will provide important insights into potential therapeutic targets designed to prevent or reverse muscle dysfunction during aging and disease.
Collapse
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.)
| |
Collapse
|
6
|
|
7
|
Defective endoplasmic reticulum-mitochondria contacts and bioenergetics in SEPN1-related myopathy. Cell Death Differ 2020; 28:123-138. [PMID: 32661288 PMCID: PMC7853070 DOI: 10.1038/s41418-020-0587-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 06/11/2020] [Accepted: 06/25/2020] [Indexed: 01/19/2023] Open
Abstract
SEPN1-related myopathy (SEPN1-RM) is a muscle disorder due to mutations of the SEPN1 gene, which is characterized by muscle weakness and fatigue leading to scoliosis and life-threatening respiratory failure. Core lesions, focal areas of mitochondria depletion in skeletal muscle fibers, are the most common histopathological lesion. SEPN1-RM underlying mechanisms and the precise role of SEPN1 in muscle remained incompletely understood, hindering the development of biomarkers and therapies for this untreatable disease. To investigate the pathophysiological pathways in SEPN1-RM, we performed metabolic studies, calcium and ATP measurements, super-resolution and electron microscopy on in vivo and in vitro models of SEPN1 deficiency as well as muscle biopsies from SEPN1-RM patients. Mouse models of SEPN1 deficiency showed marked alterations in mitochondrial physiology and energy metabolism, suggesting that SEPN1 controls mitochondrial bioenergetics. Moreover, we found that SEPN1 was enriched at the mitochondria-associated membranes (MAM), and was needed for calcium transients between ER and mitochondria, as well as for the integrity of ER-mitochondria contacts. Consistently, loss of SEPN1 in patients was associated with alterations in body composition which correlated with the severity of muscle weakness, and with impaired ER-mitochondria contacts and low ATP levels. Our results indicate a role of SEPN1 as a novel MAM protein involved in mitochondrial bioenergetics. They also identify a systemic bioenergetic component in SEPN1-RM and establish mitochondria as a novel therapeutic target. This role of SEPN1 contributes to explain the fatigue and core lesions in skeletal muscle as well as the body composition abnormalities identified as part of the SEPN1-RM phenotype. Finally, these results point out to an unrecognized interplay between mitochondrial bioenergetics and ER homeostasis in skeletal muscle. They could therefore pave the way to the identification of biomarkers and therapeutic drugs for SEPN1-RM and for other disorders in which muscle ER-mitochondria cross-talk are impaired.
Collapse
|
8
|
Lawal TA, Wires ES, Terry NL, Dowling JJ, Todd JJ. Preclinical model systems of ryanodine receptor 1-related myopathies and malignant hyperthermia: a comprehensive scoping review of works published 1990-2019. Orphanet J Rare Dis 2020; 15:113. [PMID: 32381029 PMCID: PMC7204063 DOI: 10.1186/s13023-020-01384-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/14/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Pathogenic variations in the gene encoding the skeletal muscle ryanodine receptor (RyR1) are associated with malignant hyperthermia (MH) susceptibility, a life-threatening hypermetabolic condition and RYR1-related myopathies (RYR1-RM), a spectrum of rare neuromuscular disorders. In RYR1-RM, intracellular calcium dysregulation, post-translational modifications, and decreased protein expression lead to a heterogenous clinical presentation including proximal muscle weakness, contractures, scoliosis, respiratory insufficiency, and ophthalmoplegia. Preclinical model systems of RYR1-RM and MH have been developed to better understand underlying pathomechanisms and test potential therapeutics. METHODS We conducted a comprehensive scoping review of scientific literature pertaining to RYR1-RM and MH preclinical model systems in accordance with the PRISMA Scoping Reviews Checklist and the framework proposed by Arksey and O'Malley. Two major electronic databases (PubMed and EMBASE) were searched without language restriction for articles and abstracts published between January 1, 1990 and July 3, 2019. RESULTS Our search yielded 5049 publications from which 262 were included in this review. A majority of variants tested in RYR1 preclinical models were localized to established MH/central core disease (MH/CCD) hot spots. A total of 250 unique RYR1 variations were reported in human/rodent/porcine models with 95% being missense substitutions. The most frequently reported RYR1 variant was R614C/R615C (human/porcine total n = 39), followed by Y523S/Y524S (rabbit/mouse total n = 30), I4898T/I4897T/I4895T (human/rabbit/mouse total n = 20), and R163C/R165C (human/mouse total n = 18). The dyspedic mouse was utilized by 47% of publications in the rodent category and its RyR1-null (1B5) myotubes were transfected in 23% of publications in the cellular model category. In studies of transfected HEK-293 cells, 57% of RYR1 variations affected the RyR1 channel and activation core domain. A total of 15 RYR1 mutant mouse strains were identified of which ten were heterozygous, three were compound heterozygous, and a further two were knockout. Porcine, avian, zebrafish, C. elegans, canine, equine, and drosophila model systems were also reported. CONCLUSIONS Over the past 30 years, there were 262 publications on MH and RYR1-RM preclinical model systems featuring more than 200 unique RYR1 variations tested in a broad range of species. Findings from these studies have set the foundation for therapeutic development for MH and RYR1-RM.
Collapse
Affiliation(s)
- Tokunbor A Lawal
- National Institute of Nursing Research, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Emily S Wires
- National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Nancy L Terry
- National Institutes of Health Library, National Institutes of Health, Bethesda, MD, USA
| | - James J Dowling
- Program for Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Joshua J Todd
- National Institute of Nursing Research, National Institutes of Health, Bethesda, MD, 20892, USA.
| |
Collapse
|
9
|
Boncompagni S, Pozzer D, Viscomi C, Ferreiro A, Zito E. Physical and Functional Cross Talk Between Endo-Sarcoplasmic Reticulum and Mitochondria in Skeletal Muscle. Antioxid Redox Signal 2020; 32:873-883. [PMID: 31825235 DOI: 10.1089/ars.2019.7934] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Significance: The physiological relevance of contacts between the sarcoplasmic reticulum (SR), a specialized domain of the endoplasmic reticulum (ER) in skeletal muscle, and mitochondria is still not clear. Recent Advances: An extensive close proximity of these two organelles is a late developmental event, which suggests that it does not have an essential function. Critical Issues: The intimate association of SR/mitochondria develops during murine postnatal differentiation and the recovery of denervated atrophic muscle, which suggests that this is a highly regulated process with a specific function. Analyses of mouse models for muscle diseases suggest that impaired ER/SR-mitochondrial contacts may be due to ER stress and lead to defective bioenergetics and insulin signaling. Future Directions: Future studies are necessary to identify the molecular determinants weakening insulin signaling upon impairment of ER/mitochondrial contacts in skeletal muscles as well as to analyze the distance between SR/ER and mitochondria in muscle diseases associated with ER stress.
Collapse
Affiliation(s)
- Simona Boncompagni
- CeSI-Met-Center for Research on Ageing and Translational Medicine, University G. d' Annunzio, Chieti, Italy.,DNICS-Department of Neuroscience, Imaging and Clinical Sciences, University G. d' Annunzio, Chieti, Italy
| | - Diego Pozzer
- Istituto di Ricerche Farmacologiche Mario Negri-IRCCS, Milan, Italy
| | - Carlo Viscomi
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Ana Ferreiro
- Unit of Functional and Adaptive Biology, BFA, Pathophysiology of Striated Muscles Laboratory, University Paris Diderot/CNRS, Sorbonne Paris Cité, Paris, France.,AP-HP, Centre de Référence Maladies Neuromusculaires Paris-Est, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Ester Zito
- Istituto di Ricerche Farmacologiche Mario Negri-IRCCS, Milan, Italy
| |
Collapse
|
10
|
Fusto A, Moyle LA, Gilbert PM, Pegoraro E. Cored in the act: the use of models to understand core myopathies. Dis Model Mech 2019; 12:dmm041368. [PMID: 31874912 PMCID: PMC6955215 DOI: 10.1242/dmm.041368] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The core myopathies are a group of congenital myopathies with variable clinical expression - ranging from early-onset skeletal-muscle weakness to later-onset disease of variable severity - that are identified by characteristic 'core-like' lesions in myofibers and the presence of hypothonia and slowly or rather non-progressive muscle weakness. The genetic causes are diverse; central core disease is most often caused by mutations in ryanodine receptor 1 (RYR1), whereas multi-minicore disease is linked to pathogenic variants of several genes, including selenoprotein N (SELENON), RYR1 and titin (TTN). Understanding the mechanisms that drive core development and muscle weakness remains challenging due to the diversity of the excitation-contraction coupling (ECC) proteins involved and the differential effects of mutations across proteins. Because of this, the use of representative models expressing a mature ECC apparatus is crucial. Animal models have facilitated the identification of disease progression mechanisms for some mutations and have provided evidence to help explain genotype-phenotype correlations. However, many unanswered questions remain about the common and divergent pathological mechanisms that drive disease progression, and these mechanisms need to be understood in order to identify therapeutic targets. Several new transgenic animals have been described recently, expanding the spectrum of core myopathy models, including mice with patient-specific mutations. Furthermore, recent developments in 3D tissue engineering are expected to enable the study of core myopathy disease progression and the effects of potential therapeutic interventions in the context of human cells. In this Review, we summarize the current landscape of core myopathy models, and assess the hurdles and opportunities of future modeling strategies.
Collapse
Affiliation(s)
- Aurora Fusto
- Department of Neuroscience, University of Padua, Padua 35128, Italy
| | - Louise A Moyle
- Donnelly Centre, University of Toronto, Toronto, ON M5S3E1, Canada
- Institute of Biomaterials and Biochemical Engineering, University of Toronto, Toronto, ON M5S3G9, Canada
| | - Penney M Gilbert
- Donnelly Centre, University of Toronto, Toronto, ON M5S3E1, Canada
- Institute of Biomaterials and Biochemical Engineering, University of Toronto, Toronto, ON M5S3G9, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S3G5, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON M5S1A8, Canada
| | - Elena Pegoraro
- Department of Neuroscience, University of Padua, Padua 35128, Italy
| |
Collapse
|
11
|
Suman M, Sharpe JA, Bentham RB, Kotiadis VN, Menegollo M, Pignataro V, Molgó J, Muntoni F, Duchen MR, Pegoraro E, Szabadkai G. Inositol trisphosphate receptor-mediated Ca2+ signalling stimulates mitochondrial function and gene expression in core myopathy patients. Hum Mol Genet 2019; 27:2367-2382. [PMID: 29701772 PMCID: PMC6005141 DOI: 10.1093/hmg/ddy149] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 04/16/2018] [Indexed: 12/19/2022] Open
Abstract
Core myopathies are a group of childhood muscle disorders caused by mutations of the ryanodine receptor (RyR1), the Ca2+ release channel of the sarcoplasmic reticulum. These mutations have previously been associated with elevated inositol trisphosphate receptor (IP3R) levels in skeletal muscle myotubes derived from patients. However, the functional relevance and the relationship of IP3R mediated Ca2+ signalling with the pathophysiology of the disease is unclear. It has also been suggested that mitochondrial dysfunction underlies the development of central and diffuse multi-mini-cores, devoid of mitochondrial activity, which is a key pathological consequence of RyR1 mutations. Here we used muscle biopsies of central core and multi-minicore disease patients with RyR1 mutations, as well as cellular and in vivo mouse models of the disease to characterize global cellular and mitochondrial Ca2+ signalling, mitochondrial function and gene expression associated with the disease. We show that RyR1 mutations that lead to the depletion of the channel are associated with increased IP3-mediated nuclear and mitochondrial Ca2+ signals and increased mitochondrial activity. Moreover, western blot and microarray analysis indicated enhanced mitochondrial biogenesis at the transcriptional and protein levels and was reflected in increased mitochondrial DNA content. The phenotype was recapitulated by RYR1 silencing in mouse cellular myotube models. Altogether, these data indicate that remodelling of skeletal muscle Ca2+ signalling following loss of functional RyR1 mediates bioenergetic adaptation.
Collapse
Affiliation(s)
- Matteo Suman
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy.,Neuromuscular Unit, Department of Neuroscience, University of Padova, 35131 Padua, Italy
| | - Jenny A Sharpe
- Department of Cell and Developmental Biology, Consortium for Mitochondrial Research, University College London, London WC1E 6BT, UK
| | - Robert B Bentham
- Department of Cell and Developmental Biology, Consortium for Mitochondrial Research, University College London, London WC1E 6BT, UK.,The Francis Crick Institute, London NW1 1AT, UK
| | - Vassilios N Kotiadis
- Department of Cell and Developmental Biology, Consortium for Mitochondrial Research, University College London, London WC1E 6BT, UK
| | - Michela Menegollo
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Viviana Pignataro
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Jordi Molgó
- Commissariat à l'Energie Atomique et aux Énergies Alternatives (CEA), Institut des Sciences du Vivant Frédéric Joliot, Université Paris-Saclay, Service d'Ingénierie Moléculaire des Protéines, Gif-sur-Yvette 91191, France.,Institut des Neurosciences Paris-Saclay, UMR 9197, Centre National de la Recherche Scientifique (CNRS)/Université Paris-Sud, Gif-sur-Yvette 91198, France
| | - Francesco Muntoni
- University College London, Great Ormond Street Institute of Child Health Dubowitz Neuromuscular Centre and Medical Research Council (MRC) Centre for Neuromuscular Diseases, London WC1N 1EH, UK
| | - Michael R Duchen
- Department of Cell and Developmental Biology, Consortium for Mitochondrial Research, University College London, London WC1E 6BT, UK
| | - Elena Pegoraro
- Neuromuscular Unit, Department of Neuroscience, University of Padova, 35131 Padua, Italy
| | - Gyorgy Szabadkai
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy.,Department of Cell and Developmental Biology, Consortium for Mitochondrial Research, University College London, London WC1E 6BT, UK.,The Francis Crick Institute, London NW1 1AT, UK
| |
Collapse
|
12
|
Lavorato M, Loro E, Debattisti V, Khurana TS, Franzini-Armstrong C. Elongated mitochondrial constrictions and fission in muscle fatigue. J Cell Sci 2018; 131:jcs221028. [PMID: 30404834 PMCID: PMC6288074 DOI: 10.1242/jcs.221028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 10/30/2018] [Indexed: 12/24/2022] Open
Abstract
Mitochondria respond to stress and undergo fusion and fission at variable rates, depending on cell status. To understand mitochondrial behavior during muscle fatigue, we investigated mitochondrial ultrastructure and expression levels of a fission- and stress-related protein in fast-twitch muscle fibers of mice subjected to fatigue testing. Mice were subjected to running at increasing speed until exhaustion at 45 min-1 h. In further experiments, high-intensity muscle stimulation through the sciatic nerve simulated the forced treadmill exercise. We detected a rare phenotype characterized by elongated mitochondrial constrictions (EMCs) connecting two separate segments of the original organelles. EMCs are rare in resting muscles and their frequency increases, albeit still at low levels, in stimulated muscles. The constrictions are accompanied by elevated phosphorylation of Drp1 (Dnm1l) at Ser 616, indicating an increased translocation of Drp1 to the mitochondrial membrane. This is indicative of a mitochondrial stress response, perhaps leading to or facilitating a long-lasting fission event. A close apposition of sarcoplasmic reticulum (SR) to the constricted areas, detected using both transmission and scanning electron microscopy, is highly suggestive of SR involvement in inducing mitochondrial constrictions.
Collapse
Affiliation(s)
- Manuela Lavorato
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Genetics, Children's Hospital of Philadelphia, PA 19104, USA
| | - Emanuele Loro
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Valentina Debattisti
- MitoCare Center, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Tejvir S Khurana
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Clara Franzini-Armstrong
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| |
Collapse
|
13
|
A chemical chaperone improves muscle function in mice with a RyR1 mutation. Nat Commun 2017; 8:14659. [PMID: 28337975 PMCID: PMC5376670 DOI: 10.1038/ncomms14659] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 01/20/2017] [Indexed: 12/28/2022] Open
Abstract
Mutations in the RYR1 gene cause severe myopathies. Mice with an I4895T mutation in the type 1 ryanodine receptor/Ca2+ release channel (RyR1) display muscle weakness and atrophy, but the underlying mechanisms are unclear. Here we show that the I4895T mutation in RyR1 decreases the amplitude of the sarcoplasmic reticulum (SR) Ca2+ transient, resting cytosolic Ca2+ levels, muscle triadin content and calsequestrin (CSQ) localization to the junctional SR, and increases endoplasmic reticulum (ER) stress/unfolded protein response (UPR) and mitochondrial ROS production. Treatment of mice carrying the I4895T mutation with a chemical chaperone, sodium 4-phenylbutyrate (4PBA), reduces ER stress/UPR and improves muscle function, but does not restore SR Ca2+ transients in I4895T fibres to wild type levels, suggesting that decreased SR Ca2+ release is not the major driver of the myopathy. These findings suggest that 4PBA, an FDA-approved drug, has potential as a therapeutic intervention for RyR1 myopathies that are associated with ER stress. Mutations in the RyR1 channel cause core myopathies. Here the authors show that ER stress and the unfolded protein response underlie the pathology caused by a common RyR1 channel mutation, and show that treatment with a chemical chaperone restores muscle function in mice.
Collapse
|
14
|
Pietrangelo L, D'Incecco A, Ainbinder A, Michelucci A, Kern H, Dirksen RT, Boncompagni S, Protasi F. Age-dependent uncoupling of mitochondria from Ca2⁺ release units in skeletal muscle. Oncotarget 2016; 6:35358-71. [PMID: 26485763 PMCID: PMC4742110 DOI: 10.18632/oncotarget.6139] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 09/22/2015] [Indexed: 12/03/2022] Open
Abstract
Calcium release units (CRUs) and mitochondria control myoplasmic [Ca2+] levels and ATP production in muscle, respectively. We recently reported that these two organelles are structurally connected by tethers, which promote proximity and proper Ca2+ signaling. Here we show that disposition, ultrastructure, and density of CRUs and mitochondria and their reciprocal association are compromised in muscle from aged mice. Specifically, the density of CRUs and mitochondria is decreased in muscle fibers from aged (>24 months) vs. adult (3-12 months), with an increased percentage of mitochondria being damaged and misplaced from their normal triadic position. A significant reduction in tether (13.8±0.4 vs. 5.5±0.3 tethers/100μm2) and CRU-mitochondrial pair density (37.4±0.8 vs. 27.0±0.7 pairs/100μm2) was also observed in aged mice. In addition, myoplasmic Ca2+ transient (1.68±0.08 vs 1.37±0.03) and mitochondrial Ca2+ uptake (9.6±0.050 vs 6.58±0.54) during repetitive high frequency tetanic stimulation were significantly decreased. Finally oxidative stress, assessed from levels of 3-nitrotyrosine (3-NT), Cu/Zn superoxide-dismutase (SOD1) and Mn superoxide dismutase (SOD2) expression, were significantly increased in aged mice. The reduced association between CRUs and mitochondria with aging may contribute to impaired cross-talk between the two organelles, possibly resulting in reduced efficiency in activity-dependent ATP production and, thus, to age-dependent decline of skeletal muscle performance.
Collapse
Affiliation(s)
- Laura Pietrangelo
- CeSI - Center for Research on Aging & DNICS, Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio, Chieti, Italy
| | - Alessandra D'Incecco
- CeSI - Center for Research on Aging & DNICS, Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio, Chieti, Italy
| | - Alina Ainbinder
- Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Antonio Michelucci
- CeSI - Center for Research on Aging & DNICS, Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio, Chieti, Italy
| | - Helmut Kern
- Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation & Institute of Physical Medicine and Rehabilitation, Wilhelminenspital, Vienna, Austria
| | - Robert T Dirksen
- Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Simona Boncompagni
- CeSI - Center for Research on Aging & DNICS, Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio, Chieti, Italy
| | - Feliciano Protasi
- CeSI - Center for Research on Aging & DNICS, Department of Neuroscience, Imaging and Clinical Sciences, University G. d'Annunzio, Chieti, Italy
| |
Collapse
|
15
|
Lavorato M, Gupta PK, Hopkins PM, Franzini-Armstrong C. Skeletal Muscle Microalterations in Patients Carrying Malignant Hyperthermia-Related Mutations of the e-c Coupling Machinery. Eur J Transl Myol 2016; 26:6105. [PMID: 28078069 PMCID: PMC5220216 DOI: 10.4081/ejtm.2016.6105] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
We have compared the ultrastructure of skeletal muscle biopsies from patients that have survived a [Malignant Hyperthermia, MH] episode and siblings that test positive for MH susceptibility with those from siblings that tested negatives. The aim is to establish whether life long exposure to the MH-related mutation effects may result in subtle abnormalities even in the absence of active episodes and/or clinically detectable deficiencies. Although a specific ultrastructural signature for MH mutants cannot be demonstrated, an MH related pattern of minor alterations does exist. These include the tendency for micro damage to the contractile apparatus and a higher than normal level of mitochondrial abnormalities.
Collapse
Affiliation(s)
- Manuela Lavorato
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine , Philadelphia PA, USA
| | - Pawan K Gupta
- Malignant Hyperthermia Unit, Leeds Institute of Biomedical and Clinical Sciences, St James's University Hospital , Leeds, UK
| | - Philip M Hopkins
- Malignant Hyperthermia Unit, Leeds Institute of Biomedical and Clinical Sciences, St James's University Hospital , Leeds, UK
| | - Clara Franzini-Armstrong
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine , Philadelphia PA, USA
| |
Collapse
|
16
|
Perni S, Close M, Franzini-Armstrong C. Design Principles of Reptilian Muscles: Calcium Cycling Strategies. Anat Rec (Hoboken) 2015; 299:352-60. [PMID: 26663776 DOI: 10.1002/ar.23302] [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: 07/03/2015] [Revised: 10/08/2015] [Accepted: 10/29/2015] [Indexed: 11/07/2022]
Abstract
The ultrastructure of the sarcoplasmic reticulum (SR) in skeletal muscles was compared among different reptile species (watersnake, boa constrictor, lizard, and turtle) and a mammal (mouse). Morphometric analysis demonstrates a pattern of increasing calsequestrin (CASQ) content in the lumen of SR from turtle to lizard, watersnake, and boa constrictor, and this content is in all cases higher than in mouse. In all reptiles sampled except turtle, CASQ is not confined to the junctional sarcoplasmic reticulum (jSR) cisternae as it is in other species. It instead fills the entire longitudinal (free) SR (fSR) regions, and in the extreme case of snakes, the shape of the SR is modified around the extra CASQ. We suggest that high CASQ content may represent an ATP-saving adaptation that permits relatively low metabolic rates during prolonged periods of fasting and inactivity, particularly in watersnake and boa constrictor.
Collapse
Affiliation(s)
- Stefano Perni
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Matthew Close
- Department of Biological Sciences, Williams Annex., Lehigh University, Bethlehem, Pennsylvania
| | - Clara Franzini-Armstrong
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, Pennsylvania
| |
Collapse
|
17
|
Kern H, Jakubiec-Puka A, Carraro U. Editorial: The EJTM Special "Mobility in Elderly". Eur J Transl Myol 2015; 25:208-13. [PMID: 26913158 PMCID: PMC4748983 DOI: 10.4081/ejtm.2015.5412] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Not available.
Collapse
|
18
|
Lavorato M, Huang TQ, Iyer VR, Perni S, Meissner G, Franzini-Armstrong C. Dyad content is reduced in cardiac myocytes of mice with impaired calmodulin regulation of RyR2. J Muscle Res Cell Motil 2015; 36:205-14. [DOI: 10.1007/s10974-015-9405-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 01/24/2015] [Indexed: 11/27/2022]
|
19
|
Hanson MG, Wilde JJ, Moreno RL, Minic AD, Niswander L. Potassium dependent rescue of a myopathy with core-like structures in mouse. eLife 2015; 4. [PMID: 25564733 PMCID: PMC4309926 DOI: 10.7554/elife.02923] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 01/07/2015] [Indexed: 01/24/2023] Open
Abstract
Myopathies decrease muscle functionality. Mutations in ryanodine receptor 1 (RyR1) are often associated with myopathies with microscopic core-like structures in the muscle fiber. In this study, we identify a mouse RyR1 model in which heterozygous animals display clinical and pathological hallmarks of myopathy with core-like structures. The RyR1 mutation decreases sensitivity to activated calcium release and myoplasmic calcium levels, subsequently affecting mitochondrial calcium and ATP production. Mutant muscle shows a persistent potassium leak and disrupted expression of regulators of potassium homeostasis. Inhibition of KATP channels or increasing interstitial potassium by diet or FDA-approved drugs can reverse the muscle weakness, fatigue-like physiology and pathology. We identify regulators of potassium homeostasis as biomarkers of disease that may reveal therapeutic targets in human patients with myopathy of central core disease (CCD). Altogether, our results suggest that amelioration of potassium leaks through potassium homeostasis mechanisms may minimize muscle damage of myopathies due to certain RyR1 mutations.
Collapse
Affiliation(s)
- M Gartz Hanson
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, United States
| | - Jonathan J Wilde
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, United States
| | - Rosa L Moreno
- Department of Physiology, University of Colorado, Anschutz Medical Campus, Aurora, United States
| | - Angela D Minic
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, United States
| | - Lee Niswander
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, United States
| |
Collapse
|
20
|
The disorders of the calcium release unit of skeletal muscles: what have we learned from mouse models? J Muscle Res Cell Motil 2014; 36:61-9. [PMID: 25424378 DOI: 10.1007/s10974-014-9396-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 10/29/2014] [Indexed: 01/01/2023]
Abstract
Calcium storage, release, and reuptake are essential for normal physiological function of muscle. Several human skeletal muscle disorders can arise from dysfunction in the control and coordination of these three critical processes. The release from the Sarcoplasmic Reticulum stores (SR) is handled by a multiprotein complex called Calcium Release Unit and composed of DiHydroPyridine Receptor or DHPR, Ryanodine Receptor or RYR, Calsequestrin or CASQ, junctin, Triadin, Junctophilin and Mitsugumin 29. Malignant hyperthermia (MH), Central Core Disease (CCD), Exertional/environmental Heat Stroke (EHS) and Multiminicore disease (MmD) are inherited disorders of calcium homeostasis in skeletal muscles directly related to mutations of genes coding for proteins of the CRU, primarily ryanodine receptor (RYR1). To understand the pathophysiology of MH and CCD, four murine lines carrying point mutations of human RYR1 have been developed: Y524S, R163C, I4898T and T4826I. Mice carrying those mutations show a phenotype with the traits of MH and/or CCD. Interestingly, also ablation of skeletal muscle calsequestrin (CASQ1) leads to a phenotype with MH-like lethal episodes in response to halothane and heat stress and development of central cores. In this review, we aim to describe the murine lines with RYR mutations or CASQ ablation, which show a phenotype similar to human MH or CCD, to underline their specific phenotypes and their differences and to discuss their contribution to the understanding of the pathophysiology of the disorders and the development of therapeutic strategies.
Collapse
|
21
|
Editors T. CIR-Myo News: Proceedings of the 2014 Spring Padua Muscle Days: Terme Euganee and Padova (Italy), April 3-5, 2014. Eur J Transl Myol 2014; 24:3299. [PMID: 26913130 PMCID: PMC4749006 DOI: 10.4081/ejtm.2014.3299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Not available.
Collapse
|
22
|
Carraro U, Coletti D, Kern H. The Ejtm Specials "The Long-Term Denervated Muscle". Eur J Transl Myol 2014; 24:3292. [PMID: 26913124 PMCID: PMC4749000 DOI: 10.4081/ejtm.2014.3292] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
|
23
|
Perni S, Close M, Franzini-Armstrong C. Novel details of calsequestrin gel conformation in situ. J Biol Chem 2013; 288:31358-62. [PMID: 24025332 DOI: 10.1074/jbc.m113.507749] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calsequestrin (CASQ) is the major component of the sarcoplasmic reticulum (SR) lumen in skeletal and cardiac muscles. This calcium-binding protein localizes to the junctional SR (jSR) cisternae, where it is responsible for the storage of large amounts of Ca(2+), whereas it is usually absent, at least in its polymerized form, in the free SR. The retention of CASQ inside the jSR is due partly to its association with other jSR proteins, such as junctin and triadin, and partly to its ability to polymerize, in a high Ca(2+) environment, into an intricate gel that holds the protein in place. In this work, we shed some light on the still poorly described in situ structure of polymerized CASQ using detailed EM images from thin sections, with and without tilting, and from deep-etched rotary-shadowed replicas. The latter directly illustrate the fundamental network nature of polymerized CASQ, revealing repeated nodal points connecting short segments of the linear polymer.
Collapse
Affiliation(s)
- Stefano Perni
- From the Department of Cell Developmental Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6058 and
| | | | | |
Collapse
|
24
|
Pietrangelo T, Perni S, Di Tano G, Fanò-Illic G, Franzini-Armstrong C. A method for the ultrastructural preservation of tiny percutaneous needle biopsy material from skeletal muscle. Int J Mol Med 2013; 32:965-70. [PMID: 23900509 PMCID: PMC3812242 DOI: 10.3892/ijmm.2013.1454] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 06/06/2013] [Indexed: 12/01/2022] Open
Abstract
Skeletal muscle biopsies require transecting the muscle fibers resulting, in structural damage near the cut ends. Classically, the optimal ultrastructural preservation has been obtained by the use of relatively large biopsies in which the tissue fibers are restrained by ligating to a suitable retaining support prior to excision, and by examining regions at some distance from the cut ends. However, these methods require invasive surgical procedures. In the present study, we present and substantiate an alternative approach that allows for the excellent ultrastructural preservation of needle biopsy samples, even the very small samples obtained through tiny percutaneous needle biopsy (TPNB). TPNB represents an advantage, relative to standard muscle biopsy techniques and to other needle biopsies currently in use, as in addition to not requiring a skin incision, it leaves no scars in the muscle and requires an extremely brief recovery period. It is most appropriate for obtaining repeated samples in horizontal studies, e.g., in order to follow changes with athletic training and/or aging in a single individual and for studies of sarcopenic muscles in elderly patients. Due to the small size of the sample, TPNB may present limited usefulness for classical pathology diagnostics. However, it offers the major advantage of allowing multiple samples within a single session and this may be useful under specific circumstances.
Collapse
Affiliation(s)
- Tiziana Pietrangelo
- Department of Neuroscience and Imaging, Section of Physiology and Physiopathology, G. d'Annunzio University of Chieti-Pescara and Clinical Research Center of G. d'Annunzio Foundation, Chieti I-66100, Italy
| | | | | | | | | |
Collapse
|
25
|
Lefebvre R, Legrand C, Groom L, Dirksen RT, Jacquemond V. Ca2+ release in muscle fibers expressing R4892W and G4896V type 1 ryanodine receptor disease mutants. PLoS One 2013; 8:e54042. [PMID: 23308296 PMCID: PMC3538700 DOI: 10.1371/journal.pone.0054042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 12/05/2012] [Indexed: 12/17/2022] Open
Abstract
The large and rapidly increasing number of potentially pathological mutants in the type 1 ryanodine receptor (RyR1) prompts the need to characterize their effects on voltage-activated sarcoplasmic reticulum (SR) Ca2+ release in skeletal muscle. Here we evaluated the function of the R4892W and G4896V RyR1 mutants, both associated with central core disease (CCD) in humans, in myotubes and in adult muscle fibers. For both mutants expressed in RyR1-null (dyspedic) myotubes, voltage-gated Ca2+ release was absent following homotypic expression and only partially restored following heterotypic expression with wild-type (WT) RyR1. In muscle fibers from adult WT mice, both mutants were expressed in restricted regions of the fibers with a pattern consistent with triadic localization. Voltage-clamp-activated confocal Ca2+ signals showed that fiber regions endowed with G4896V-RyR1s exhibited an ∼30% reduction in the peak rate of SR Ca2+ release, with no significant change in SR Ca2+ content. Immunostaining revealed no associated change in the expression of either α1S subunit (Cav1.1) of the dihydropyridine receptor (DHPR) or type 1 sarco(endo)plasmic reticulum Ca2+ ATPase (SERCA1), indicating that the reduced Ca2+ release resulted from defective RyR1 function. Interestingly, in spite of robust localized junctional expression, the R4892W mutant did not affect SR Ca2+ release in adult muscle fibers, consistent with a low functional penetrance of this particular CCD-associated mutant.
Collapse
Affiliation(s)
- Romain Lefebvre
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, CNRS UMR 5534 – Université Lyon 1, Villeurbanne, France
| | - Claude Legrand
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, CNRS UMR 5534 – Université Lyon 1, Villeurbanne, France
| | - Linda Groom
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Robert T. Dirksen
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Vincent Jacquemond
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, CNRS UMR 5534 – Université Lyon 1, Villeurbanne, France
- * E-mail:
| |
Collapse
|
26
|
Allele-specific gene silencing in two mouse models of autosomal dominant skeletal myopathy. PLoS One 2012; 7:e49757. [PMID: 23152933 PMCID: PMC3495761 DOI: 10.1371/journal.pone.0049757] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 10/17/2012] [Indexed: 12/16/2022] Open
Abstract
We explored the potential of mutant allele-specific gene silencing (ASGS) in providing therapeutic benefit in two established mouse models of the autosomal dominantly-inherited muscle disorders, Malignant Hyperthermia (MH) and Central Core Disease (CCD). Candidate ASGS siRNAs were designed and validated for efficacy and specificity on ryanodine receptor (RyR1) cDNA mini-constructs expressed in HEK293 cells using RT-PCR- and confocal microscopy-based assays. In vivo delivery of the most efficacious identified siRNAs into flexor digitorum brevis (FDB) muscles was achieved by injection/electroporation of footpads of 4–6 month old heterozygous Ryr1Y524S/+ (YS/+) and Ryr1I4895T/+ (IT/+) knock-in mice, established mouse models of MH with cores and CCD, respectively. Treatment of IT/+ mice resulted in a modest rescue of deficits in the maximum rate (∼38% rescue) and magnitude (∼78%) of ligand-induced Ca2+ release that occurred in the absence of a change in the magnitude of electrically-evoked Ca2+ release. Compared to the difference between the caffeine sensitivity of Ca2+ release in FDB fibers from YS/+ and WT mice treated with SCR siRNA (EC50: 1.1 mM versus 4.4 mM, respectively), caffeine sensitivity was normalized in FDB fibers from YS/+ mice following 2 (EC50: 2.8 mM) and 4 week (EC50: 6.6 mM) treatment with YS allele-specific siRNA. Moreover, the temperature-dependent increase in resting Ca2+ observed in FDB fibers from YS/+ mice was normalized to WT levels after 2 weeks of treatment with YS allele-specific siRNA. As determined by quantitative real time PCR, the degree of functional rescue in YS/+ and IT/+ mice correlated well with the relative increase in fractional WT allele expression.
Collapse
|
27
|
Klein A, Lillis S, Munteanu I, Scoto M, Zhou H, Quinlivan R, Straub V, Manzur AY, Roper H, Jeannet PY, Rakowicz W, Jones DH, Jensen UB, Wraige E, Trump N, Schara U, Lochmuller H, Sarkozy A, Kingston H, Norwood F, Damian M, Kirschner J, Longman C, Roberts M, Auer-Grumbach M, Hughes I, Bushby K, Sewry C, Robb S, Abbs S, Jungbluth H, Muntoni F. Clinical and genetic findings in a large cohort of patients with ryanodine receptor 1 gene-associated myopathies. Hum Mutat 2012; 33:981-8. [PMID: 22473935 DOI: 10.1002/humu.22056] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 02/07/2012] [Indexed: 11/12/2022]
Abstract
Ryanodine receptor 1 (RYR1) mutations are a common cause of congenital myopathies associated with both dominant and recessive inheritance. Histopathological findings frequently feature central cores or multi-minicores, more rarely, type 1 predominance/uniformity, fiber-type disproportion, increased internal nucleation, and fatty and connective tissue. We describe 71 families, 35 associated with dominant RYR1 mutations and 36 with recessive inheritance. Five of the dominant mutations and 35 of the 55 recessive mutations have not been previously reported. Dominant mutations, typically missense, were frequently located in recognized mutational hotspot regions, while recessive mutations were distributed throughout the entire coding sequence. Recessive mutations included nonsense and splice mutations expected to result in reduced RyR1 protein. There was wide clinical variability. As a group, dominant mutations were associated with milder phenotypes; patients with recessive inheritance had earlier onset, more weakness, and functional limitations. Extraocular and bulbar muscle involvement was almost exclusively observed in the recessive group. In conclusion, our study reports a large number of novel RYR1 mutations and indicates that recessive variants are at least as frequent as the dominant ones. Assigning pathogenicity to novel mutations is often difficult, and interpretation of genetic results in the context of clinical, histological, and muscle magnetic resonance imaging findings is essential.
Collapse
Affiliation(s)
- Andrea Klein
- Paediatric Neurology, University Children's Hospital Zurich, Zurich, Switzerland
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Boncompagni S, Protasi F, Franzini-Armstrong C. Sequential stages in the age-dependent gradual formation and accumulation of tubular aggregates in fast twitch muscle fibers: SERCA and calsequestrin involvement. AGE (DORDRECHT, NETHERLANDS) 2012; 34:27-41. [PMID: 21318331 PMCID: PMC3260353 DOI: 10.1007/s11357-011-9211-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 01/24/2011] [Indexed: 05/30/2023]
Abstract
Tubular aggregates (TAs), ordered arrays of elongated sarcoplasmic reticulum (SR) tubules, are present in skeletal muscle from patients with myopathies and are also experimentally induced by extreme anoxia. In wild-type mice TAs develop in a clear age-, sex- (male), and fiber type- (fast twitch) dependence. However, the events preceding the appearance of TAs have not been explored. We investigated the sequential stages leading to the initial appearance and maturation of TAs in EDL from male mice. TAs' formation requires two temporally distinct steps that operate via different mechanisms. Initially (before 1 year of age), the SR Ca(2+) binding protein calsequestrin (CASQ) accumulates specifically at the I band level causing swelling of free SR cisternae. In the second stage, the enlarged SR sacs at the I band level extend into multiple, longitudinally oriented tubules with a full complement of sarco(endo)plasmic reticulum Ca(2+) ATPases (SERCA) in the membrane and CASQ in the lumen. Tubules gradually acquire a regular cylindrical shape and uniform size apparently in concert with partial crystallization of SERCA. Multiple, small TAs associate to form fewer mature TAs of very large size. Interestingly, in fibers from CASQ1-knockout mice abnormal aggregates of SR tubules have different conformation and never develop into ordered aggregates of straight cylinders, possibly due to lack of CASQ accumulation. We conclude that TAs do not arise abruptly but are the final result of a gradually changing SR architecture and we suggest that the crystalline ATPase within the aggregates may be inactive.
Collapse
Affiliation(s)
- Simona Boncompagni
- IIM-Interuniversitary Institute of Myology, DNI-Department of Neuroscience and Imaging, CeSI-Centro Scienze dell'Invecchiamento, Università degli Studi G. d'Annunzio, 66013, Chieti, Italy.
| | | | | |
Collapse
|
29
|
Type 1 ryanodine receptor knock-in mutation causing central core disease of skeletal muscle also displays a neuronal phenotype. Proc Natl Acad Sci U S A 2011; 109:610-5. [PMID: 22203976 DOI: 10.1073/pnas.1115111108] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The type 1 ryanodine receptor (RyR1) is expressed widely in the brain, with high levels in the cerebellum, hippocampus, and hypothalamus. We have shown that L-type Ca(2+) channels in terminals of hypothalamic magnocellular neurons are coupled to RyRs, as they are in skeletal muscle, allowing voltage-induced Ca(2+) release (VICaR) from internal Ca(2+) stores without Ca(2+) influx. Here we demonstrate that RyR1 plays a role in VICaR in nerve terminals. Furthermore, in heterozygotes from the Ryr1(I4895T/WT) (IT/+) mouse line, carrying a knock-in mutation corresponding to one that causes a severe form of human central core disease, VICaR is absent, demonstrating that type 1 RyR mediates VICaR and that these mice have a neuronal phenotype. The absence of VICaR was shown in two ways: first, depolarization in the absence of Ca(2+) influx elicited Ca(2+)syntillas (scintilla, spark, in a nerve terminal, a SYNaptic structure) in WT, but not in mutant terminals; second, in the presence of extracellular Ca(2+), IT/+ terminals showed a twofold decrease in global Ca(2+) transients, with no change in plasmalemmal Ca(2+) current. From these studies we draw two conclusions: (i) RyR1 plays a role in VICaR in hypothalamic nerve terminals; and (ii) a neuronal alteration accompanies the myopathy in IT/+ mice, and, possibly in humans carrying the corresponding RyR1 mutation.
Collapse
|
30
|
Yuen B, Boncompagni S, Feng W, Yang T, Lopez JR, Matthaei KI, Goth SR, Protasi F, Franzini-Armstrong C, Allen PD, Pessah IN. Mice expressing T4826I-RYR1 are viable but exhibit sex- and genotype-dependent susceptibility to malignant hyperthermia and muscle damage. FASEB J 2011; 26:1311-22. [PMID: 22131268 DOI: 10.1096/fj.11-197582] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Mutation T4825I in the type 1 ryanodine receptor (RYR1(T4825I/+)) confers human malignant hyperthermia susceptibility (MHS). We report a knock-in mouse line that expresses the isogenetic mutation T4826I. Heterozygous RYR1(T4826I/+) (Het) or homozygous RYR1(T4826I/T4826I) (Hom) mice are fully viable under typical rearing conditions but exhibit genotype- and sex-dependent susceptibility to environmental conditions that trigger MH. Hom mice maintain higher core temperatures than WT in the home cage, have chronically elevated myoplasmic[Ca(2+)](rest), and present muscle damage in soleus with a strong sex bias. Mice subjected to heat stress in an enclosed 37°C chamber fail to trigger MH regardless of genotype, whereas heat stress at 41°C invariably triggers fulminant MH in Hom, but not Het, mice within 20 min. WT and Het female mice fail to maintain euthermic body temperature when placed atop a bed whose surface is 37°C during halothane anesthesia (1.75%) and have no hyperthermic response, whereas 100% Hom mice of either sex and 17% of the Het males develop fulminant MH. WT mice placed on a 41°C bed maintain body temperature while being administered halothane, and 40% of the Het females and 100% of the Het males develop fulminant MH within 40 min. Myopathic alterations in soleus were apparent by 12 mo, including abnormally distributed and enlarged mitochondria, deeply infolded sarcolemma, and frequent Z-line streaming regions, which were more severe in males. These data demonstrate that an MHS mutation within the S4-S5 cytoplasmic linker of RYR1 confers genotype- and sex-dependent susceptibility to pharmacological and environmental stressors that trigger fulminant MH and promote myopathy.
Collapse
Affiliation(s)
- Benjamin Yuen
- Department of Veterinary Molecular Biosciences, University of California, Davis, California, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Lefebvre R, Legrand C, González-Rodríguez E, Groom L, Dirksen RT, Jacquemond V. Defects in Ca2+ release associated with local expression of pathological ryanodine receptors in mouse muscle fibres. J Physiol 2011; 589:5361-82. [PMID: 21969454 DOI: 10.1113/jphysiol.2011.216408] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Mutations of the gene encoding the type 1 ryanodine receptor (RyR1) are associated with skeletal muscle disorders including malignant hyperthermia susceptibility (MHS) and central core disease (CCD). We used in vivo expression of EGFP-RyR1 constructs in fully differentiated mouse muscle fibres to characterize the function of several RyR1 mutants. Wild-type and Y523S, R615C, R2163H and I4897T mutants of RyR1 were separately expressed and found to be present within restricted regions of fibres with a pattern consistent with triadic localization. Confocal measurements of voltage-clamp-activated myoplasmic Ca(2+) transients demonstrated alterations of sarcoplasmic reticulum (SR) Ca(2+) release spatially correlated with the presence of exogenous RyR1s. The Y523S, R615C and R2163H RyR1 MHS-related mutants were associated with enhanced peak Ca(2+) release for low and moderate levels of depolarization, whereas the I4897T CCD mutant produced a chronic reduction of peak SR Ca(2+) release. For example, peak Ca(2+) release in response to a depolarization to -20 mV in regions of fibres expressing Y523S and I4897T was 2.0 ± 0.3 (n = 9) and 0.46 ± 0.1 (n = 5) times the corresponding value in adjacent, non-expressing regions of the same fibre, respectively. Interestingly no significant change in the estimated total amount of Ca(2+) released at the end of large depolarizing pulses was observed for any of the mutant RyR1 channels. Overall, results are consistent with an 'inherent' increase in RyR1 sensitivity to activation by the voltage sensor for the MHS-related RyR1 mutants and a partial failure of voltage-gated release for the CCD-related I4897T mutant, that occur with no sign of change in SR Ca(2+) content. Furthermore, the results indicate that RyR1 channel density is tightly regulated even under the present conditions of forced exogenous expression.
Collapse
Affiliation(s)
- Romain Lefebvre
- CNRS UMR 5534, Université Lyon 1, Centre de Génétique et de Physiologie Moléculaire et Cellulaire, Villeurbanne, France
| | | | | | | | | | | |
Collapse
|
32
|
Differential effect of calsequestrin ablation on structure and function of fast and slow skeletal muscle fibers. J Biomed Biotechnol 2011; 2011:634075. [PMID: 21941434 PMCID: PMC3173739 DOI: 10.1155/2011/634075] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Accepted: 07/12/2011] [Indexed: 12/02/2022] Open
Abstract
We compared structure and function of EDL and Soleus muscles in adult (4–6 m) mice lacking both Calsequestrin (CASQ) isoforms, the main SR Ca2+-binding proteins. Lack of CASQ induced ultrastructural alterations in ~30% of Soleus fibers, but not in EDL. Twitch time parameters were prolonged in both muscles, although tension was not reduced. However, when stimulated for 2 sec at 100 hz, Soleus was able to sustain contraction, while in EDL active tension declined by 70–80%. The results presented in this paper unmask a differential effect of CASQ1&2 ablation in fast versus slow fibers. CASQ is essential in EDL to provide large amount of Ca2+ released from the SR during tetanic stimulation. In contrast, Soleus deals much better with lack of CASQ because slow fibers require lower Ca2+ amounts and slower cycling to function properly. Nevertheless, Soleus suffers more severe structural damage, possibly because SR Ca2+ leak is more pronounced.
Collapse
|
33
|
Increased muscle stress-sensitivity induced by selenoprotein N inactivation in mouse: a mammalian model for SEPN1-related myopathy. PLoS One 2011; 6:e23094. [PMID: 21858002 PMCID: PMC3152547 DOI: 10.1371/journal.pone.0023094] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 07/12/2011] [Indexed: 11/24/2022] Open
Abstract
Selenium is an essential trace element and selenoprotein N (SelN) was the first selenium-containing protein shown to be directly involved in human inherited diseases. Mutations in the SEPN1 gene, encoding SelN, cause a group of muscular disorders characterized by predominant affection of axial muscles. SelN has been shown to participate in calcium and redox homeostasis, but its pathophysiological role in skeletal muscle remains largely unknown. To address SelN function in vivo, we generated a Sepn1-null mouse model by gene targeting. The Sepn1−/− mice had normal growth and lifespan, and were macroscopically indistinguishable from wild-type littermates. Only minor defects were observed in muscle morphology and contractile properties in SelN-deficient mice in basal conditions. However, when subjected to challenging physical exercise and stress conditions (forced swimming test), Sepn1−/− mice developed an obvious phenotype, characterized by limited motility and body rigidity during the swimming session, as well as a progressive curvature of the spine and predominant alteration of paravertebral muscles. This induced phenotype recapitulates the distribution of muscle involvement in patients with SEPN1-Related Myopathy, hence positioning this new animal model as a valuable tool to dissect the role of SelN in muscle function and to characterize the pathophysiological process.
Collapse
|
34
|
Capes EM, Loaiza R, Valdivia HH. Ryanodine receptors. Skelet Muscle 2011; 1:18. [PMID: 21798098 PMCID: PMC3156641 DOI: 10.1186/2044-5040-1-18] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 05/04/2011] [Indexed: 12/31/2022] Open
Abstract
Excitation-contraction coupling involves the faithful conversion of electrical stimuli to mechanical shortening in striated muscle cells, enabled by the ubiquitous second messenger, calcium. Crucial to this process are ryanodine receptors (RyRs), the sentinels of massive intracellular calcium stores contained within the sarcoplasmic reticulum. In response to sarcolemmal depolarization, RyRs release calcium into the cytosol, facilitating mobilization of the myofilaments and enabling cell contraction. In order for the cells to relax, calcium must be rapidly resequestered or extruded from the cytosol. The sustainability of this cycle is crucially dependent upon precise regulation of RyRs by numerous cytosolic metabolites and by proteins within the lumen of the sarcoplasmic reticulum and those directly associated with the receptors in a macromolecular complex. In addition to providing the majority of the calcium necessary for contraction of cardiac and skeletal muscle, RyRs act as molecular switchboards that integrate a multitude of cytosolic signals such as dynamic and steady calcium fluctuations, β-adrenergic stimulation (phosphorylation), nitrosylation and metabolic states, and transduce these signals to the channel pore to release appropriate amounts of calcium. Indeed, dysregulation of calcium release via RyRs is associated with life-threatening diseases in both skeletal and cardiac muscle. In this paper, we briefly review some of the most outstanding structural and functional attributes of RyRs and their mechanism of regulation. Further, we address pathogenic RyR dysfunction implicated in cardiovascular disease and skeletal myopathies.
Collapse
Affiliation(s)
- E Michelle Capes
- Department of Cellular and Regenerative Biology, University of Wisconsin Medical School, Madison, WI 53711, USA.
| | | | | |
Collapse
|
35
|
Loy RE, Orynbayev M, Xu L, Andronache Z, Apostol S, Zvaritch E, MacLennan DH, Meissner G, Melzer W, Dirksen RT. Muscle weakness in Ryr1I4895T/WT knock-in mice as a result of reduced ryanodine receptor Ca2+ ion permeation and release from the sarcoplasmic reticulum. ACTA ACUST UNITED AC 2010; 137:43-57. [PMID: 21149547 PMCID: PMC3010056 DOI: 10.1085/jgp.201010523] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The type 1 isoform of the ryanodine receptor (RYR1) is the Ca(2+) release channel of the sarcoplasmic reticulum (SR) that is activated during skeletal muscle excitation-contraction (EC) coupling. Mutations in the RYR1 gene cause several rare inherited skeletal muscle disorders, including malignant hyperthermia and central core disease (CCD). The human RYR1(I4898T) mutation is one of the most common CCD mutations. To elucidate the mechanism by which RYR1 function is altered by this mutation, we characterized in vivo muscle strength, EC coupling, SR Ca(2+) content, and RYR1 Ca(2+) release channel function using adult heterozygous Ryr1(I4895T/+) knock-in mice (IT/+). Compared with age-matched wild-type (WT) mice, IT/+ mice exhibited significantly reduced upper body and grip strength. In spite of normal total SR Ca(2+) content, both electrically evoked and 4-chloro-m-cresol-induced Ca(2+) release were significantly reduced and slowed in single intact flexor digitorum brevis fibers isolated from 4-6-mo-old IT/+ mice. The sensitivity of the SR Ca(2+) release mechanism to activation was not enhanced in fibers of IT/+ mice. Single-channel measurements of purified recombinant channels incorporated in planar lipid bilayers revealed that Ca(2+) permeation was abolished for homotetrameric IT channels and significantly reduced for heterotetrameric WT:IT channels. Collectively, these findings indicate that in vivo muscle weakness observed in IT/+ knock-in mice arises from a reduction in the magnitude and rate of RYR1 Ca(2+) release during EC coupling that results from the mutation producing a dominant-negative suppression of RYR1 channel Ca(2+) ion permeation.
Collapse
Affiliation(s)
- Ryan E Loy
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|