p38 mitogen-activated protein kinase and mitogen-activated protein kinase-activated protein kinase 2 (MK2) signaling in atrophic and hypertrophic denervated mouse skeletal muscle.
Kim Evertsson, Ann-Kristin Fjällström, Marlene Norrby, Sven Tågerud
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引用次数: 8
Abstract
Background: p38 mitogen-activated protein kinase has been implicated in both skeletal muscle atrophy and hypertrophy. T317 phosphorylation of the p38 substrate mitogen-activated protein kinase-activated protein kinase 2 (MK2) correlates with muscle weight in atrophic and hypertrophic denervated muscle and may influence the nuclear and cytoplasmic distribution of p38 and/or MK2. The present study investigates expression and phosphorylation of p38, MK2 and related proteins in cytosolic and nuclear fractions from atrophic and hypertrophic 6-days denervated skeletal muscles compared to innervated controls.
Methods: Expression and phosphorylation of p38, MK2, Hsp25 (heat shock protein25rodent/27human, Hsp25/27) and Hsp70 protein expression were studied semi-quantitatively using Western blots with separated nuclear and cytosolic fractions from innervated and denervated hypertrophic hemidiaphragm and atrophic anterior tibial muscles. Unfractionated innervated and denervated atrophic pooled gastrocnemius and soleus muscles were also studied.
Results: No support was obtained for a differential nuclear/cytosolic localization of p38 or MK2 in denervated hypertrophic and atrophic muscle. The differential effect of denervation on T317 phosphorylation of MK2 in denervated hypertrophic and atrophic muscle was not reflected in p38 phosphorylation nor in the phosphorylation of the MK2 substrate Hsp25. Hsp25 phosphorylation increased 3-30-fold in all denervated muscles studied. The expression of Hsp70 increased 3-5-fold only in denervated hypertrophic muscles.
Conclusions: The study confirms a differential response of MK2 T317 phosphorylation in denervated hypertrophic and atrophic muscles and suggests that Hsp70 may be important for this. Increased Hsp25 phosphorylation in all denervated muscles studied indicates a role for factors other than MK2 in the regulation of this phosphorylation.
期刊介绍：
Journal of Molecular Signaling is an open access, peer-reviewed online journal that encompasses all aspects of molecular signaling. Molecular signaling is an exponentially growing field that encompasses different molecular aspects of cell signaling underlying normal and pathological conditions. Specifically, the research area of the journal is on the normal or aberrant molecular mechanisms involving receptors, G-proteins, kinases, phosphatases, and transcription factors in regulating cell proliferation, differentiation, apoptosis, and oncogenesis in mammalian cells. This area also covers the genetic and epigenetic changes that modulate the signaling properties of cells and the resultant physiological conditions.
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