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This Article Full Text Full Text (PDF) All Versions of this Article: 104/5/1476    most recent 00708.2007v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Kosek, D. J. Articles by Bamman, M. M. PubMed PubMed Citation Articles by Kosek, D. J. Articles by Bamman, M. M.

Modulation of the dystrophin-associated protein complex in response to resistance training in young and older men

Department of Physiology and Biophysics, The University of Alabama at Birmingham, and Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Birmingham, Alabama

Submitted 1 July 2007 ; accepted in final form 20 March 2008

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), ₁-syntrophin (increased 16% by T3, P < 0.05), -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 (Ser¹⁴¹⁷) 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.

muscle hypertrophy; mechanotransduction; caveolin-3; ₁-syntrophin; p38 mitogen-activated protein kinase