HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 292/5/C1681    most recent 00466.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Shi, H. Articles by Gerrard, D. E. Search for Related Content PubMed PubMed Citation Articles by Shi, H. Articles by Gerrard, D. E.

MUSCLE CELL BIOLOGY AND CELL MOTILITY

Extracellular signal-regulated kinase pathway is differentially involved in -agonist-induced hypertrophy in slow and fast muscles

¹Department of Animal Sciences and ²Department of Basic Medical Sciences, Purdue University, West Lafayette, Indiana

Submitted 30 August 2006 ; accepted in final form 24 November 2006

The molecular mechanisms controlling -adrenergic receptor agonist (BA)-induced skeletal muscle hypertrophy are not well known. We presently report that BA exerts a distinct muscle- and muscle fiber type-specific hypertrophy. Moreover, we have shown that pharmacologically or genetically attenuating extracellular signal-regulated kinase (ERK) signaling in muscle fibers resulted in decreases (P < 0.05) in fast but not slow fiber type-specific reporter gene expressions in response to BA exposure in vitro and in vivo. Consistent with these data, forced expression of MAPK phosphatase 1, a nuclear protein that dephosphorylates ERK1/2, in fast-twitch skeletal muscle ablated (P < 0.05) the hypertrophic effects of BA feeding (clenbuterol, 20 parts per million in water) in vivo. Further analysis has shown that BA-induced phosphorylation and activation of ERK occurred to a greater (P < 0.05) extent in fast myofibers than in slow myofibers. Analysis of the basal level of ERK activity in slow and fast muscles revealed that ERK1/2 is activated to a greater extent in fast- than in slow-twitch muscles. These data indicate that ERK signaling is differentially involved in BA-induced hypertrophy in slow and fast skeletal muscles, suggesting that the increased abundance of phospho-ERK1/2 and ERK activity found in fast-twitch myofibers, compared with their slow-twitch counterparts, may account, at least in part, for the fiber type-specific hypertrophy induced by BA stimulation. These data suggest that fast myofibers are pivotal in the adaptation of muscle to environmental cues and that the mechanism underlying this change is partially mediated by the MAPK signaling cascade.

muscle fiber type; mitogen-activated protein kinase signaling pathways; mechanism

This article has been cited by other articles:

				V. Ljubicic and D. A. Hood Kinase-specific responsiveness to incremental contractile activity in skeletal muscle with low and high mitochondrial content Am J Physiol Endocrinol Metab, July 1, 2008; 295(1): E195 - E204. [Abstract] [Full Text] [PDF]

				M. J. Drummond, H. C. Dreyer, B. Pennings, C. S. Fry, S. Dhanani, E. L. Dillon, M. Sheffield-Moore, E. Volpi, and B. B. Rasmussen Skeletal muscle protein anabolic response to resistance exercise and essential amino acids is delayed with aging J Appl Physiol, May 1, 2008; 104(5): 1452 - 1461. [Abstract] [Full Text] [PDF]