Expression profile of plakin cross-linking proteins in short-term denervated mouse hindlimb skeletal muscle

Abstract

Purpose:

Skeletal muscle atrophy linked to neuromuscular inactivity is a complex phenomenon involving widespread alteration of muscle structure and function. Plakin cross-linking proteins are important structural elements that are expressed in skeletal muscles, which require resistance to mechanical stress. The plakin proteins most prevalent in skeletal muscles are plectin, dystonin, and microtubule-actin cross-linking factor (MACF). The expression profile of plakin cross-linking proteins in skeletal muscles during atrophy is poorly understood. We therefore investigated the expression profile of plectin, dystonin, and MACF in mouse hindlimb muscles undergoing denervation-induced atrophy.

Materials and methods:

Quantitative polymerase chain reaction and Western blotting were performed to assess plakin mRNA and protein expression in mouse gastrocnemius muscles that were denervated for 1 day, 3 days, 7 days, and 14 days. The left hindlimb muscles were denervated by severing the left sciatic nerve, and the contralateral limb muscles served as sham control muscles. The mRNA expression of myogenin and acetylcholinesterase was measured in parallel and served as controls.

Results:

As expected, myogenin mRNA expression was substantially induced in denervated muscles (13-fold induction), whereas acetylcholinesterase expression was significantly and progressively suppressed (90% reduction) in denervated skeletal muscles. In comparison, we found that plectin and dystonin mRNA expression were progressively reduced by ~50% at day 14 denervation time point, but the protein levels remained relatively constant. On the other hand, MACF expression was upregulated approximately threefold by day 7 denervation at both the mRNA and protein levels.

Conclusion:

This study suggests that plakins may be of potential importance in the baseline preservation of the skeletal muscle structure following short-term denervation-induced atrophy. These results shed light on the gene expression profile of the skeletal muscle plakins during short-term denervation-induced atrophy.

Keywords::

• dystonin
• plectin
• MACF
• muscle atrophy

Acknowledgments

The authors would like to thank Paul Michael for his technical assistance. The current article includes work based on PB’s Masters of Human Kinetics thesis submitted while he was a graduate student at Laurentian University.

Disclosure

The authors report no conflicts of interest in this work.