Department of Cell and Developmental Biology
Medical Subject Headings
Animals; Blotting, Western; Carrier Proteins; Mice; Mice, Inbred C57BL; Mice, Inbred mdx; Mice, Knockout; Microscopy, Electron; Muscle Contraction; Muscle Fibers, Fast-Twitch; Muscle Fibers, Slow-Twitch; Muscle, Skeletal; Myocardium; Promoter Regions, Genetic; Protein Isoforms; Sarcomeres
Cell Biology | Cellular and Molecular Physiology
Myosin binding protein-C (MyBP-C) exists in three major isoforms: slow skeletal, fast skeletal, and cardiac. While cardiac MyBP-C (cMyBP-C) expression is restricted to the heart in the adult, it is transiently expressed in neonatal stages of some skeletal muscles. However, it is unclear whether this expression is necessary for the proper development and function of skeletal muscle. Our aim was to determine whether the absence of cMyBP-C alters the structure, function, or MyBP-C isoform expression in adult skeletal muscle using a cMyBP-C null mouse model (cMyBP-C((t/t))). Slow MyBP-C was expressed in both slow and fast skeletal muscles, whereas fast MyBP-C was mostly restricted to fast skeletal muscles. Expression of these isoforms was unaffected in skeletal muscle from cMyBP-C((t/t)) mice. Slow and fast skeletal muscles in cMyBP-C((t/t)) mice showed no histological or ultrastructural changes in comparison to the wild-type control. In addition, slow muscle twitch, tetanus tension, and susceptibility to injury were all similar to the wild-type controls. Interestingly, fMyBP-C expression was significantly increased in the cMyBP-C((t/t)) hearts undergoing severe dilated cardiomyopathy, though this does not seem to prevent dysfunction. Additionally, expression of both slow and fast isoforms was increased in myopathic skeletal muscles. Our data demonstrate that i) MyBP-C isoforms are differentially regulated in both cardiac and skeletal muscles, ii) cMyBP-C is dispensable for the development of skeletal muscle with no functional or structural consequences in the adult myocyte, and iii) skeletal isoforms can transcomplement in the heart in the absence of cMyBP-C.
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Citation: Lin B, Govindan S, Lee K, Zhao P, Han R, Runte KE, Craig R, Palmer BM, Sadayappan S. Cardiac myosin binding protein-C plays no regulatory role in skeletal muscle structure and function. PLoS One. 2013 Jul 31;8(7):e69671. doi:10.1371/journal.pone.0069671. Link to article on publisher's site