Fura-2 imaging of spontaneous and electrically induced oscillations of intracellular free Ca2+ in rat myotubes

Grouselle, Michel; Koenig, Jeanine; Lascombe, M. L.; Chapron, Jacqueline; Méléard, Philippe; Georgescauld, D.

doi:10.1007/bf00370450

Cited by 32 publications

(29 citation statements)

References 51 publications

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“…In some species, including mouse, the maturation of the E-C coupling mechanism proceeds even in the absence of the nerve (29,39,40). In contrast, in human muscle cells, the nerve plays a critical role in the subcellular distribution and expression of L-type Ca 2ϩ channels and RyRs, in the formation of striated junctions, and in the establishment of the E-C coupling mechanism (14).…”

Section: Discussionmentioning

confidence: 99%

Neural agrin controls maturation of the excitation-contraction coupling mechanism in human myotubes developing in vitro

Bandi¹,

Jevsek²,

Marš³

et al. 2008

American Journal of Physiology-Cell Physiology

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The aim of this study was to elucidate the mechanisms responsible for the effects of innervation on the maturation of excitation-contraction coupling apparatus in human skeletal muscle. For this purpose, we compared the establishment of the excitation-contraction coupling mechanism in myotubes differentiated in four different experimental paradigms: 1) aneurally cultured, 2) cocultured with fetal rat spinal cord explants, 3) aneurally cultured in medium conditioned by cocultures, and 4) aneurally cultured in medium supplemented with purified recombinant chick neural agrin. Ca(2+) imaging indicated that coculturing human muscle cells with rat spinal cord explants increased the fraction of cells showing a functional excitation-contraction coupling mechanism. The effect of spinal cord explants was mimicked by treatment with medium conditioned by cocultures or by addition of 1 nM of recombinant neural agrin to the medium. The treatment with neural agrin increased the number of human muscle cells in which functional ryanodine receptors (RyRs) and dihydropyridine-sensitive L-type Ca(2+) channels were detectable. Our data are consistent with the hypothesis that agrin, released from neurons, controls the maturation of the excitation-contraction coupling mechanism and that this effect is due to modulation of both RyRs and L-type Ca(2+) channels. Thus, a novel role for neural agrin in skeletal muscle maturation is proposed.

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Section: Discussionmentioning

confidence: 99%

Neural agrin controls maturation of the excitation-contraction coupling mechanism in human myotubes developing in vitro

Bandi¹,

Jevsek²,

Marš³

et al. 2008

American Journal of Physiology-Cell Physiology

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“…(Fong et al, 1990;Grassi et al, 1994;Bakker et al, 1997). The r e s t i n g [Ca2+]i of cultured primary rat myotubes (Grouselle et al, 1991;Cognard et al, 1993;Jaimovich and Rojas, 1994) is higher than that of L 6 muscle cells, which is independent of the composition of the differentiation medium. The responses of [Ca2+]i on addition of acetylcholine, a high concentration of KC1, or caffeine to the perfusion fluid establish the presence of a functional excitation-contraction coupling in C2C12 myotubes (Grassi et al, 1994), as has been observed in cultured mouse and human muscle ceils (Benders et al, 1997a(Benders et al, , 1997bSteeghs et al, 1997).…”

Section: Hs Ubementioning

confidence: 94%

Differentiation markers of mouse C2C12 and rat L6 myogenic cell lines and the effect of the differentiation medium

Portier

Benders

Oosterhof

et al. 1999

In Vitro Cell.Dev.Biol.-Animal

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The differentiation grade of cells in culture is dependent on the composition of the culture medium. Two commonly used myogenic cell lines, mouse C2C12 and rat L6, usually differentiate at a low concentration of horse serum. In this study we compared the effect of horse serum with a medium containing a low percentage of Ultroser G and rat brain extract. The maturation grade was evaluated on the basis of various biochemical, (immuno)histochemical and cell-physiological parameters. Substitution of horse serum by Ultroser G and rat brain extract during the differentiation phase resulted in a higher maturation grade of the myotubes of both cell lines, on the basis of creatine kinase activity and the diameter of the myotubes. In addition, the C2C12 myotubes display cross-striation, contain a higher percentage of creatine kinase muscle-specific isoenzyme MM, show a ninefold increase in acetylcholine receptor (AChR) clusters, form a continuous basement membrane, and have a lower resting cytosolic Ca2+ concentration. L6 myotubes show a fivefold increase in AChR clusters and a twofold increase in the expression of the mRNA of the epsilon-subunit of AChR.C2C12 cells show spontaneous contraction and response of cytosolic Ca2+ to various stimulants in contrast to L6 cells which do not. These studies established that the Ultroser G/brain extract medium leads to a higher differentiation grade of both cell lines, but parameters appropriate for use as differentiation markers appear to differ between both cell lines.

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“…On the other hand, skeletal muscle cells develop excitability and contractile properties during the first stages of myogenesis. This phenotype has been associated to the onset of voltage-dependent channel protein expression (sodium and calcium channels) and to the maturation of the excitation-contraction apparatus (7)(8)(9). At more advanced developmental stages, muscle activity is controlled by motor innervation (10).…”

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confidence: 99%

Transforming Growth Factor β (TGF-β) Signaling Is Regulated by Electrical Activity in Skeletal Muscle Cells

Ugarte¹,

Brandan

2006

Journal of Biological Chemistry

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Transforming growth factor (TGF-␤) is involved in several cellular processes such as cell proliferation, differentiation, and apoptosis. At the cell surface, TGF-␤ binds to serine-threonine kinase transmembrane receptors (type II and type I) to initiate Smad-dependent intracellular signaling cascades. During the early stages of skeletal muscle differentiation, myotubes start to evoke spontaneous electrical activity in association with contractions that arise following the maturation of the excitation-contraction apparatus. In this work, we report that TGF-␤-dependent signaling is regulated by electrical activity in developing rat primary myotubes, as determined by Smad2 phosphorylation, Smad4 nuclear translocation, and p3TPLux reporter activity. This electrical activity-dependent regulation is associated with changes in TGF-␤ type I receptor (T␤RI) levels, correlated with changes in transducing receptors at the cell membrane (measured through radiolabeling binding assays). The inhibition of electrical activity with tetrodotoxin, a voltage-dependent sodium channel blocker, increases T␤RI levels via a transcription-dependent mechanism. In contrast, the promotion of electrical activity in myotube cultures, induced by the upregulation of voltage-dependent sodium channels or by direct stimulation with extracellular electrodes, causes T␤RI levels to decrease. Similar results were obtained in denervated adult muscles, suggesting that electrical activity-dependent regulation of T␤RI also occurs in vivo. Additional results suggest that this activitydependent regulation is mediated by myogenin. Altogether, these findings support the possibility for a novel regulatory mechanism acting on TGF-␤ signaling cascade in skeletal muscle cells.

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Fura-2 imaging of spontaneous and electrically induced oscillations of intracellular free Ca2+ in rat myotubes

Cited by 32 publications

References 51 publications

Neural agrin controls maturation of the excitation-contraction coupling mechanism in human myotubes developing in vitro

Neural agrin controls maturation of the excitation-contraction coupling mechanism in human myotubes developing in vitro

Differentiation markers of mouse C2C12 and rat L6 myogenic cell lines and the effect of the differentiation medium

Transforming Growth Factor β (TGF-β) Signaling Is Regulated by Electrical Activity in Skeletal Muscle Cells

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