Modulation of the dystrophin-associated protein complex in response to resistance training in young and older men.
The dystrophin-associated protein complex (DAPC) is a scaffold of proteins linking the intracellular cytoskeleton with the extracellular matrix that is integral to structural stability and integrity, signaling and mechanotransduction, and force transmission. We hypothesized that the expression of DAPC component proteins would be altered by resistance loading during progressive resistance training (PRT)-mediated myofiber hypertrophy, and we investigated whether aging influenced these changes. Seventeen young (27 yr) and 13 older (65 yr) men completed 16 wk of PRT with muscle biopsies at baseline (T1), 24 h after bout 1 (T2), and 24 h after the final bout at week 16 (T3). Myofiber hypertrophy in the young (type I 31%, P < 0.005; type II 40%, P < 0.001) far exceeded hypertrophy in the old (type II only, 19.5%, P < 0.05). PRT altered protein expression for caveolin-3 (decreased 24% by T3, P < 0.01), alpha(1)-syntrophin (increased 16% by T3, P < 0.05), alpha-dystrobrevin (fell 23% from T2 to T3, P < 0.01), and dystrophin [rose acutely (30% by T2, P < 0.05) and returned to baseline by T3]. The phosphorylation state of membrane neuronal nitric oxide synthase (Ser(1417)) decreased 70% (P < 0.005) by T3, particularly in the old (81%), whereas p38 MAPK phosphorylation increased twofold by T3 in the old (P < 0.01). We conclude that component proteins of the DAPC are modulated by PRT, which may serve to improve both structural and signaling functions during load-mediated myofiber hypertrophy. The blunted hypertrophic adaptation seen in old vs. young men may have resulted from overstress, as suggested by marked p38 MAPK activation in old men only.
Kosek
David J
DJ
Department of Physiology and Biophysics, Core Muscle Research Laboratory, University of Alabama at Birmingham, 1530 3rd Avenue South, Birmingham, AL 35294-0005, USA.
Bamman
Marcas M
MM
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001642:Bicycling / Q000502:physiology; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000096:biosynthesis; D051244:Caveolin 3 / Q000096:biosynthesis; D048429:Cell Size; D003080:Cold Temperature; D049029:Dystrophin-Associated Proteins / Q000096:biosynthesis / Q000502:physiology*; D006801:Humans; D049449:Luminescence; D008297:Male; D040542:Mechanotransduction, Cellular / Q000502:physiology; D008565:Membrane Proteins / Q000096:biosynthesis; D008875:Middle Aged; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology; D048052:Mitogen-Activated Protein Kinase 3 / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000502:physiology / Q000648:ultrastructure; D009124:Muscle Proteins / Q000096:biosynthesis; D018482:Muscle, Skeletal / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism; D010809:Physical Fitness / Q000502:physiology*; D013312:Stress, Physiological / Q000503:physiopathology; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology
D002135:Calcium-Binding Proteins; D051244:Caveolin 3; D049029:Dystrophin-Associated Proteins; D008565:Membrane Proteins; D009124:Muscle Proteins; C098885:dystrobrevin; C091825:syntrophin alpha1; D052248:Nitric Oxide Synthase Type I; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases