Cong X, Doering J, Grange RW, Jiang H. Defective excitation-contraction coupling is partially responsible for impaired contractility in hindlimb muscles of Stac3 knockout mice.
Sci Rep 2016;
6:26194. [PMID:
27184118 PMCID:
PMC4868984 DOI:
10.1038/srep26194]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 04/28/2016] [Indexed: 01/13/2023] Open
Abstract
The Stac3 gene is exclusively expressed in skeletal muscle, and Stac3 knockout is perinatal lethal in mice. Previous data from Stac3-deleted diaphragms indicated that Stac3-deleted skeletal muscle could not contract because of defective excitation-contraction (EC) coupling. In this study, we determined the contractility of Stac3-deleted hindlimb muscle. In response to frequent electrostimulation, Stac3-deleted hindlimb muscle contracted but the maximal tension generated was only 20% of that in control (wild type or heterozygous) muscle (P < 0.05). In response to high [K(+)], caffeine, and 4-chloro-m-cresol (4-CMC), the maximal tensions generated in Stac3-deleted muscle were 29% (P < 0.05), 58% (P = 0.08), and 55% (P < 0.05) of those in control muscle, respectively. In response to 4-CMC or caffeine, over 90% of myotubes formed from control myoblasts contracted, but only 60% of myotubes formed from Stac3-deleted myoblasts contracted (P = 0.05). However, in response to 4-CMC or caffeine, similar increases in intracellular calcium concentration were observed in Stac3-deleted and control myotubes. Gene expression and histological analyses revealed that Stac3-deleted hindlimb muscle contained more slow type-like fibers than control muscle. These data together confirm a critical role of STAC3 in EC coupling but also suggest that STAC3 may have additional functions in skeletal muscle, at least in the hindlimb muscle.
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