Exercise-induced Protein Arginine Methyltransferase Expression in Skeletal Muscle
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PURPOSE: This study aimed to determine protein arginine methyltransferase 1 (PRMT1), -4 (also known as coactivator-associated arginine methyltransferase 1 [CARM1]), and -5 expression and function during acute, exercise-induced skeletal muscle remodeling in vivo. METHODS: C57BL/6 mice were assigned to one of three experimental groups: sedentary, acute bout of exercise, or acute exercise followed by 3 h of recovery. Mice in the exercise groups performed a single bout of treadmill running at 15 m·min for 90 min. Hindlimb muscles were collected, and quantitative real-time polymerase chain reaction and Western blotting were used to examine exercise-induced gene expression. RESULTS: The PRMT gene expression and global enzyme activity were muscle-specific, generally being higher (P < 0.05) in slow, oxidative muscle, as compared with faster, more glycolytic tissue. Despite the significant activation of canonical exercise-induced signaling involving AMP-activated protein kinase and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), PRMT expression and activity at the whole muscle level were unchanged. However, subcellular analyses revealed a significant exercise-evoked myonuclear translocation of PRMT1 before the nuclear accumulation of PGC-1α. Acute physical activity also augmented (P < 0.05) the targeted methyltransferase activities of the PRMT in the myonuclear compartment, suggesting that PRMT-mediated histone arginine methylation is part of the early signals that drive muscle plasticity. Finally, basal PGC-1α asymmetric dimethylarginine status, as well as constitutive interactions between PGC-1α and PRMT1 or CARM1 may contribute to the exercise-induced muscle remodeling process. CONCLUSIONS: The present study provides the first evidence that PRMT activity is selectively augmented during the initial activation of exercise-induced skeletal muscle remodeling in vivo. These data support the emergence of PRMTs as important players in the regulation of skeletal muscle plasticity.
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