Myosin light chain kinase and myosin phosphorylation effect frequency-dependent potentiation of skeletal muscle contraction

Gang Zhi, Jeffrey W. Ryder, Jian Huang, Peiguo Ding, Yue Chen, Yingming Zhao, Kristine E. Kamm, James T. Stull

Research output: Contribution to journalArticle

129 Citations (Scopus)

Abstract

Repetitive stimulation potentiates contractile tension of fast-twitch skeletal muscle. We examined the role of myosin regulatory light chain (RLC) phosphorylation in this physiological response by ablating Ca 2+/calmodulin-dependent skeletal muscle myosin light chain kinase (MLCK) gene expression. Western blot and quantitative-PCR showed that MLCK is expressed predominantly in fast-twitch skeletal muscle fibers with insignificant amounts in heart and smooth muscle. In contrast, smooth muscle MLCK had a more ubiquitous tissue distribution, with the greatest expression observed in smooth muscle tissue. Ablation of the MYLK2 gene in mice resulted in loss of skeletal muscle MLCK expression, with no change in smooth muscle MLCK expression. In isolated fast-twitch skeletal muscles from these knockout mice, there was no significant increase in RLC phosphorylation in response to repetitive electrical stimulation. Furthermore, isometric twitch-tension potentiation after a brief tetanus (posttetanic twitch potentiation) or low-frequency twitch potentiation (staircase) was attenuated relative to responses in muscles from wild-type mice. Interestingly, the site of phosphorylation of the small amount of monophosphorylated RLC in the knockout mice was the same site phosphorylated by MLCK, indicating a potential alternative signaling pathway affecting contractile potentiation. Loss of skeletal muscle MLCK expression had no effect on cardiac RLC phosphorylation. These results identify myosin light chain phosphorylation by the dedicated skeletal muscle Ca2+/calmodulin-dependent MLCK as a primary biochemical mechanism for tension potentiation due to repetitive stimulation in fast-twitch skeletal muscle.

Original languageEnglish (US)
Pages (from-to)17519-17524
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume102
Issue number48
DOIs
StatePublished - Nov 29 2005

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Myosin-Light-Chain Kinase
Myosins
Muscle Contraction
Skeletal Muscle
Phosphorylation
Skeletal Muscle Myosins
Smooth Muscle Myosins
Myosin Light Chains
Calmodulin
Light
Knockout Mice
Smooth Muscle
Fast-Twitch Muscle Fibers
Muscles
Skeletal Muscle Fibers
Tetanus
Tissue Distribution
Electric Stimulation
Myocardium
Western Blotting

Keywords

  • Calcium
  • Calmodulin
  • Twitch

ASJC Scopus subject areas

  • Genetics
  • General

Cite this

Myosin light chain kinase and myosin phosphorylation effect frequency-dependent potentiation of skeletal muscle contraction. / Zhi, Gang; Ryder, Jeffrey W.; Huang, Jian; Ding, Peiguo; Chen, Yue; Zhao, Yingming; Kamm, Kristine E.; Stull, James T.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 102, No. 48, 29.11.2005, p. 17519-17524.

Research output: Contribution to journalArticle

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