scholarly journals Pathological Mechanism of a Constitutively Active Form of Stromal Interaction Molecule 1 in Skeletal Muscle

Biomolecules ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1064
Author(s):  
Ji Hee Park ◽  
Seung Yeon Jeong ◽  
Jun Hee Choi ◽  
Eun Hui Lee
Keyword(s):  
Skeletal Muscle ◽  
Active Form ◽  
Muscle Stiffness ◽  
Wild Type ◽  
Stromal Interaction Molecule 1 ◽  
Skeletal Myoblasts ◽  
Transmission Electron ◽  
Pathological Mechanism ◽  
Skeletal Myotubes ◽  
Constitutively Active

Stromal interaction molecule 1 (STIM1) is the main protein that, along with Orai1, mediates store-operated Ca2+ entry (SOCE) in skeletal muscle. Abnormal SOCE due to mutations in STIM1 is one of the causes of human skeletal muscle diseases. STIM1-R304Q (a constitutively active form of STIM1) has been found in human patients with skeletal muscle phenotypes such as muscle weakness, myalgia, muscle stiffness, and contracture. However, the pathological mechanism(s) of STIM1-R304Q in skeletal muscle have not been well studied. To examine the pathological mechanism(s) of STIM1-R304Q in skeletal muscle, STIM1-R304Q was expressed in mouse primary skeletal myotubes, and the properties of the skeletal myotubes were examined using single-myotube Ca2+ imaging, transmission electron microscopy (TEM), and biochemical approaches. STIM1-R304Q did not interfere with the terminal differentiation of skeletal myoblasts to myotubes and retained the ability of STIM1 to attenuate dihydropyridine receptor (DHPR) activity. STIM1-R304Q induced hyper-SOCE (that exceeded the SOCE by wild-type STIM1) by affecting both the amplitude and the onset rate of SOCE. Unlike that by wild-type STIM1, hyper-SOCE by STIM1-R304Q contributed to a disturbance in Ca2+ distribution between the cytosol and the sarcoplasmic reticulum (SR) (high Ca2+ in the cytosol and low Ca2+ in the SR). Moreover, the hyper-SOCE and the high cytosolic Ca2+ level induced by STIM1-R304Q involve changes in mitochondrial shape. Therefore, a series of these cellular defects induced by STIM1-R304Q could induce deleterious skeletal muscle phenotypes in human patients carrying STIM1-R304Q.

scholarly journals A muscular hypotonia-associated STIM1 mutant at R429 induces abnormalities in intracellular Ca2+ movement and extracellular Ca2+ entry in skeletal muscle

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jun Hee Choi ◽  
Mei Huang ◽  
Changdo Hyun ◽  
Mi Ri Oh ◽  
Keon Jin Lee ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Initial Rate ◽  
Mitochondrial Fission ◽  
Terminal Differentiation ◽  
Muscular Hypotonia ◽  
Wild Type ◽  
Transmission Electron ◽  
Pathological Mechanism ◽  
Intracellular Ca ◽  
Skeletal Myotubes

AbstractStromal interaction molecule 1 (STIM1) mediates extracellular Ca2+ entry into the cytosol through a store-operated Ca2+ entry (SOCE) mechanism, which is involved in the physiological functions of various tissues, including skeletal muscle. STIM1 is also associated with skeletal muscle diseases, but its pathological mechanisms have not been well addressed. The present study focused on examining the pathological mechanism(s) of a mutant STIM1 (R429C) that causes human muscular hypotonia. R429C was expressed in mouse primary skeletal myotubes, and the properties of the skeletal myotubes were examined using single-cell Ca2+ imaging of myotubes and transmission electron microscopy (TEM) along with biochemical approaches. R429C did not interfere with the terminal differentiation of myoblasts to myotubes. Unlike wild-type STIM1, there was no further increase of SOCE by R429C. R429C bound to endogenous STIM1 and slowed down the initial rate of SOCE that were mediated by endogenous STIM1. Moreover, R429C increased intracellular Ca2+ movement in response to membrane depolarization by eliminating the attenuation on dihydropyridine receptor-ryanodine receptor (DHPR-RyR1) coupling by endogenous STIM1. The cytosolic Ca2+ level was also increased due to the reduction in SR Ca2+ level. In addition, R429C-expressing myotubes showed abnormalities in mitochondrial shape, a significant decrease in ATP levels, and the higher expression levels of mitochondrial fission-mediating proteins. Therefore, serial defects in SOCE, intracellular Ca2+ movement, and cytosolic Ca2+ level along with mitochondrial abnormalities in shape and ATP level could be a pathological mechanism of R429C for human skeletal muscular hypotonia. This study also suggests a novel clue that STIM1 in skeletal muscle could be related to mitochondria via regulating intra and extracellular Ca2+ movements.

Constitutively active calcineurin in skeletal muscle increases endurance performance and mitochondrial respiratory capacity

2010 ◽  
Vol 298 (1) ◽  
pp. E8-E16 ◽  
Author(s):  
Lake Q. Jiang ◽  
Pablo M. Garcia-Roves ◽  
Thais de Castro Barbosa ◽  
Juleen R. Zierath
Keyword(s):  
Skeletal Muscle ◽  
Energy Expenditure ◽  
Transgenic Mice ◽  
Exercise Performance ◽  
Endurance Performance ◽  
Wild Type ◽  
Respiratory Capacity ◽  
Edl Muscle ◽  
Mitochondrial Respiratory ◽  
Constitutively Active

Expression of an activated form of calcineurin in skeletal muscle selectively up-regulates slow-fiber-specific gene expression. Here, we tested the hypothesis that expression of activated calcineurin in skeletal muscle influences body composition, energy homeostasis, and exercise performance. Using transgenic mice expressing activated calcineurin (CnA*) in skeletal muscle (MCK-CnA* transgenic mice), we determined whether skeletal muscle reprogramming by calcineurin activation affects exercise performance and skeletal muscle mitochondrial function. Body weight and extensor digitorum longus (EDL) skeletal muscle weight were reduced 10% in MCK-CnA* mice compared with wild-type littermates. Basal oxygen consumption, food intake, and voluntary exercise behavior were unchanged between MCK-CnA* and wild-type mice. However, when total energy expenditure was normalized by fat-free mass, energy expenditure was increased in MCK-CnA* mice. An endurance performance treadmill running test revealed MCK-CnA* mice are fatigue resistant and run 50% farther before exhaustion. After a standardized exercise bout, glycogen and triglyceride content in EDL muscle was higher in MCK-CnA* vs. wild-type mice. Mitochondrial respiratory capacity was increased 35% in EDL muscle from resting MCK-CnA* mice. In conclusion, our results provide evidence to support the hypothesis that calcineurin activation in skeletal muscle increases mitochondrial oxidative function and energy substrate storage, which contributes to enhanced endurance exercise performance. These adaptive changes occur as a consequence of a lifelong expression of a constitutively active calcineurin and mimic the response to chronic endurance training.

scholarly journals Calmodulin Binding to the 3614–3643 Region of RyR1 Is Not Essential for Excitation–Contraction Coupling in Skeletal Myotubes

2002 ◽  
Vol 120 (3) ◽  
pp. 337-347 ◽  
Author(s):  
Kristen M.S. O'Connell ◽  
Naohiro Yamaguchi ◽  
Gerhard Meissner ◽  
Robert T. Dirksen
Keyword(s):  
Skeletal Muscle ◽  
Similar Degree ◽  
In Vitro Activity ◽  
Wild Type ◽  
Calmodulin Binding ◽  
Ec Coupling ◽  
Skeletal Myotubes ◽  
Sensor Activation

Calmodulin is a ubiquitous Ca2+ binding protein that modulates the in vitro activity of the skeletal muscle ryanodine receptor (RyR1). Residues 3614–3643 of RyR1 comprise the CaM binding domain and mutations within this region result in a loss of both high-affinity Ca2+-bound calmodulin (CaCaM) and Ca2+-free CaM (apoCaM) binding (L3624D) or only CaCaM binding (W3620A). To investigate the functional role of CaM binding to this region of RyR1 in intact skeletal muscle, we compared the ability of RyR1, L3624D, and W3620A to restore excitation–contraction (EC) coupling after expression in RyR1-deficient (dyspedic) myotubes. W3620A-expressing cells responded normally to 10 mM caffeine and 500 μM 4-chloro-m-cresol (4-cmc). Interestingly, L3624D-expressing cells displayed a bimodal response to caffeine, with a large proportion of cells (∼44%) showing a greatly attenuated response to caffeine. However, high and low caffeine-responsive L3624D-expressing myotubes exhibited Ca2+ transients of similar magnitude after activation by 4-cmc (500 μM) and electrical stimulation. Expression of either L3624D or W3620A in dyspedic myotubes restored both L-type Ca2+ currents (retrograde coupling) and voltage-gated SR Ca2+ release (orthograde coupling) to a similar degree as that observed for wild-type RyR1, although L-current density was somewhat larger and activated at more hyperpolarized potentials in W3620A-expressing myotubes. The results indicate that CaM binding to the 3614–3643 region of RyR1 is not essential for voltage sensor activation of RyR1.

scholarly journals Calsequestrin 1 Is an Active Partner of Stromal Interaction Molecule 2 in Skeletal Muscle

Cells ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2821
Author(s):  
Seung Yeon Jeong ◽  
Mi Ri Oh ◽  
Jun Hee Choi ◽  
Jin Seok Woo ◽  
Eun Hui Lee
Keyword(s):  
Skeletal Muscle ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Transmission Electron ◽  
Skeletal Muscle Contraction ◽  
Skeletal Myotubes ◽  
Functional Relevance ◽  
Transient Receptor ◽  
Canonical Type ◽  
Related Proteins

Calsequestrin 1 (CASQ1) in skeletal muscle buffers and senses Ca2+ in the sarcoplasmic reticulum (SR). CASQ1 also regulates store-operated Ca2+ entry (SOCE) by binding to stromal interaction molecule 1 (STIM1). Abnormal SOCE and/or abnormal expression or mutations in CASQ1, STIM1, or STIM2 are associated with human skeletal, cardiac, or smooth muscle diseases. However, the functional relevance of CASQ1 along with STIM2 has not been studied in any tissue, including skeletal muscle. First, in the present study, it was found by biochemical approaches that CASQ1 is bound to STIM2 via its 92 N-terminal amino acids (C1 region). Next, to examine the functional relevance of the CASQ1-STIM2 interaction in skeletal muscle, the full-length wild-type CASQ1 or the C1 region was expressed in mouse primary skeletal myotubes, and the myotubes were examined using single-myotube Ca2+ imaging experiments and transmission electron microscopy observations. The CASQ1-STIM2 interaction via the C1 region decreased SOCE, increased intracellular Ca2+ release for skeletal muscle contraction, and changed intracellular Ca2+ distributions (high Ca2+ in the SR and low Ca2+ in the cytosol were observed). Furthermore, the C1 region itself (which lacks Ca2+-buffering ability but has STIM2-binding ability) decreased the expression of Ca2+-related proteins (canonical-type transient receptor potential cation channel type 6 and calmodulin 1) and induced mitochondrial shape abnormalities. Therefore, in skeletal muscle, CASQ1 plays active roles in Ca2+ movement and distribution by interacting with STIM2 as well as Ca2+ sensing and buffering.

scholarly journals Electromechanical Coupling between Skeletal and Cardiac Muscle

2000 ◽  
Vol 149 (3) ◽  
pp. 731-740 ◽  
Author(s):  
Hans Reinecke ◽  
Glen H. MacDonald ◽  
Stephen D. Hauschka ◽  
Charles E. Murry
Keyword(s):  
Skeletal Muscle ◽  
Gap Junctions ◽  
Cardiac Muscle ◽  
Gap Junction ◽  
Electromechanical Coupling ◽  
Skeletal Myoblasts ◽  
Adult Cardiomyocytes ◽  
Synchronous Contraction ◽  
Skeletal Myotubes

Skeletal myoblasts form grafts of mature muscle in injured hearts, and these grafts contract when exogenously stimulated. It is not known, however, whether cardiac muscle can form electromechanical junctions with skeletal muscle and induce its synchronous contraction. Here, we report that undifferentiated rat skeletal myoblasts expressed N-cadherin and connexin43, major adhesion and gap junction proteins of the intercalated disk, yet both proteins were markedly downregulated after differentiation into myo-tubes. Similarly, differentiated skeletal muscle grafts in injured hearts had no detectable N-cadherin or connexin43; hence, electromechanical coupling did not occur after in vivo grafting. In contrast, when neonatal or adult cardiomyocytes were cocultured with skeletal muscle, ∼10% of the skeletal myotubes contracted in synchrony with adjacent cardiomyocytes. Isoproterenol increased myotube contraction rates by 25% in coculture without affecting myotubes in monoculture, indicating the cardiomyocytes were the pacemakers. The gap junction inhibitor heptanol aborted myotube contractions but left spontaneous contractions of individual cardiomyocytes intact, suggesting myotubes were activated via gap junctions. Confocal microscopy revealed the expression of cadherin and connexin43 at junctions between myotubes and neonatal or adult cardiomyocytes in vitro. After microinjection, myotubes transferred dye to neonatal cardiomyocytes via gap junctions. Calcium imaging revealed synchronous calcium transients in cardiomyocytes and myotubes. Thus, cardiomyocytes can form electromechanical junctions with some skeletal myotubes in coculture and induce their synchronous contraction via gap junctions. Although the mechanism remains to be determined, if similar junctions could be induced in vivo, they might be sufficient to make skeletal muscle grafts beat synchronously with host myocardium.

Increased IGFR activity and glucose transport in cultured skeletal muscle from insulin receptor null mice

2001 ◽  
Vol 281 (1) ◽  
pp. E16-E24 ◽  
Author(s):  
Liat Shefi-Friedman ◽  
Efrat Wertheimer ◽  
Shlomzion Shen ◽  
Asia Bak ◽  
Domenico Accili ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Growth Factor ◽  
Insulin Receptor ◽  
Glucose Transport ◽  
Contractile Activity ◽  
Primary Cultures ◽  
Insulin Like Growth Factor ◽  
Wild Type ◽  
Igf I ◽  
Skeletal Myotubes

We have studied the role of the insulin receptor (IR) in metabolic and growth-promoting effects of insulin on primary cultures of skeletal muscle derived from the limb muscle of IR null mice. Cultures of IR null skeletal muscle displayed normal morphology and spontaneous contractile activity. Expression of muscle-differentiating proteins was slightly reduced in myoblasts and myotubes of the IR null skeletal muscle cells, whereas that of the Na+/K+ pump appeared to be unchanged. Insulin-like growth factor receptor (IGFR) expression was higher in myoblasts from IR knockout (IRKO) than from IR wild-type (IRWT) mice but was essentially unchanged in myotubes. Expression of the GLUT-1 and GLUT-4 transporters appeared to be higher in IRKO than in IRWT myoblasts and was significantly greater in myotubes from IRKO than from IRWT cultures. Consistent with GLUT expression, both basal and insulin or insulin-like growth factor I (IGF-I)-stimulated glucose uptakes were higher in IR null skeletal myotubes than in wild-type skeletal myotubes. Interestingly, autophosphorylation of IGFR induced by insulin and IGF-I was markedly increased in IR null skeletal myotubes. These results indicate that, in the absence of IR, there is a compensatory increase in basal as well as in insulin- and IGF-I-induced glucose transport, the former being mediated via increased activation of the IGF-I receptor.

Enhanced calcium cycling and contractile function in transgenic hearts expressing constitutively active Gαo* protein

2008 ◽  
Vol 294 (3) ◽  
pp. H1335-H1347 ◽  
Author(s):  
Ming Zhu ◽  
Agnieszka A. Gach ◽  
GongXin Liu ◽  
Xiaomei Xu ◽  
Chee Chew Lim ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Ryanodine Receptor ◽  
Protein Phosphatase ◽  
Contractile Function ◽  
Active Form ◽  
Protein Phosphatase 1 ◽  
Wild Type ◽  
Specific Expression ◽  
Constitutively Active

In contrast to the other heterotrimeric GTP-binding proteins (G proteins) Gs and Gi, the functional role of Go is still poorly defined. To investigate the role of Gαo in the heart, we generated transgenic mice with cardiac-specific expression of a constitutively active form of Gαo1* (Gαo*), the predominant Gαo isoform in the heart. Gαo expression was increased 3- to 15-fold in mice from 5 independent lines, all of which had a normal life span and no gross cardiac morphological abnormalities. We demonstrate enhanced contractile function in Gαo* transgenic mice in vivo, along with increased L-type Ca2+ channel current density, calcium transients, and cell shortening in ventricular Gαo*-expressing myocytes compared with wild-type controls. These changes were evident at baseline and maintained after isoproterenol stimulation. Expression levels of all major Ca2+ handling proteins were largely unchanged, except for a modest reduction in Na+/Ca2+ exchanger in transgenic ventricles. In contrast, phosphorylation of the ryanodine receptor and phospholamban at known PKA sites was increased 1.6- and 1.9-fold, respectively, in Gαo* ventricles. Density and affinity of β-adrenoceptors, cAMP levels, and PKA activity were comparable in Gαo* and wild-type myocytes, but protein phosphatase 1 activity was reduced upon Gαo* expression, particularly in the vicinity of the ryanodine receptor. We conclude that Gαo* exerts a positive effect on Ca2+ cycling and contractile function. Alterations in protein phosphatase 1 activity rather than PKA-mediated phosphorylation might be involved in hyperphosphorylation of key Ca2+ handling proteins in hearts with constitutive Gαo activation.

Blood vessel formation in the tissue-engineered bone with the constitutively active form of HIF-1α mediated BMSCs

Biomaterials ◽  
2012 ◽  
Vol 33 (7) ◽  
pp. 2097-2108 ◽  
Author(s):  
Duohong Zou ◽  
Zhiyuan Zhang ◽  
Jiacai He ◽  
Kai Zhang ◽  
Dongxia Ye ◽  
...  
Keyword(s):  
Blood Vessel ◽  
Active Form ◽  
Blood Vessel Formation ◽  
Vessel Formation ◽  
Constitutively Active

scholarly journals Adhesive multiplicity in the interaction of embryonic fibroblasts and myoblasts with extracellular matrices.

1984 ◽  
Vol 99 (4) ◽  
pp. 1398-1404 ◽  
Author(s):  
C Decker ◽  
R Greggs ◽  
K Duggan ◽  
J Stubbs ◽  
A Horwitz
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Cardiac Fibroblasts ◽  
Cell Types ◽  
Extracellular Matrices ◽  
Common Denominator ◽  
Cell Matrix ◽  
Skeletal Myoblasts ◽  
A Cell ◽  
Cell Matrix Adhesion

Neff et al. (1982, J. Cell Biol., 95:654-666) have described a monoclonal antibody, CSAT, directed against a cell surface antigen that participates in the adhesion of skeletal muscle to extracellular matrices. We used the same antibody to compare and parse the determinants of adhesion and morphology on myogenic and fibrogenic cells. We report here that the antigen is present on skeletal and cardiac muscle and on tendon, skeletal, dermal, and cardiac fibroblasts; however, its contribution to their morphology and adhesion is different. The antibody produces large alterations in the morphology and adhesion of skeletal myoblasts and tendon fibroblasts; in contrast, its effects on the cardiac fibroblasts are not readily detected. The effects of CSAT on the other cell types, i.e., dermal and skeletal fibroblasts, cardiac muscle, 5-bromodeoxyuridine-treated skeletal muscle, lie between these extremes. The effects of CSAT on the skeletal myoblasts depends on the calcium concentration in the growth medium and on the culture age. We interpret these differential responses to CSAT as revealing differences in the adhesion of the various cells to extracellular matrices. This interpretation is supported by parallel studies using quantitative assays of cell-matrix adhesion. The likely origin of these adhesive differences is the progressive display of different kinds of adhesion-related molecules and their organizational complexes on increasingly adhesive cells. The antigen to which CSAT is directed is present on all of the above cells and thus appears to be a lowest common denominator of their adhesion to extracellular matrices.

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