Muscle LIM protein plays both structural and functional roles in skeletal muscle.

Barash IA, Mathew L, Lahey M, Greaser ML, Lieber RL.

Am J Physiol Cell Physiol., 2005 289: C1312-C20.

Abstract:

Muscle LIM protein (MLP) has been suggested to be an important mediator of mechanical stress in cardiac tissue, but the role that it plays in skeletal muscle remains unclear. Previous studies showed that it was dramatically upregulated in fast-to-slow fiber type transformation and also after eccentric contraction-induced muscle injury (EC). The functional consequences of this upregulation, if any, are unclear. Here we examine the skeletal muscle phenotype of MLP knockout (MLPKO) mice, in terms of their response to ECs. The data suggest that, while the MLPKO mice recover completely after EC-induced injury, torque production lags behind heterozygous littermates in the early stages of the recovery process. This lag is accompanied by decreased expression of the muscle regulatory factor MyoD, suggesting that MLP may influence gene expression. In addition, there is evidence of type 1 fiber atrophy and a shorter resting sarcomere length in the MLPKO mice, but no significant differences in fiber type distribution. In summary, MLP appears to play a subtle role in the maintenance of normal muscle characteristics and in the early events of the recovery process of skeletal muscle to injury, serving both structural and gene regulatory roles.

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