Time Course of Proteolytic, Cytokine, and Myostatin Gene Expression After Acute

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J Appl Physiol. 2007 Sep 6

Time Course of Proteolytic, Cytokine, and Myostatin Gene Expression

After Acute Exercise in Human Skeletal Muscle.

Louis ES, Raue U, Yang Y, Jemiolo B, Trappe SW.

Human Performance Laboratory, Ball State University, Muncie,

Indiana, United States.

The aim of this study was to examine the time course induction of

select proteolytic (MuRF-1, atrogin-1, FOXO3A, calpain-1, calpain-

2), myostatin, and cytokine (IL -6, -8, -15 and TNFalpha) mRNA after

an acute bout of resistance (RE) or run (RUN) exercise.

Six experienced RE (25 +/- 4 yr, 74 +/- 14 kg, 1.71 +/- 0.11 m) and

six RUN (25 +/- 4 yr, 72 +/- 5 kg, 1.81 +/- 0.07 m) subjects had

muscle biopsies from the vastus lateralis (RE) or gastrocnemius

(RUN) before, immediately after, and 1, 2, 4, 8, 12, and 24 h post

exercise. RE increased (p<0.05) mRNA expression of MuRF-1 early (3.5-

fold, 1-4 h), followed by a decrease in atrogin-1 (3.3-fold) and

FOXO3A (1.7-fold) 8-12 h post exercise.

Myostatin mRNA decreased (6.3-fold; p<0.05) from 1-24 h post

exercise, while IL-6, IL-8 and TNFalpha mRNA was elevated 2-12 h.

RUN increased (p<0.05) MuRF-1 (3.6-fold), atrogin-1 (1.6-fold) and

FOXO3A (1.9-fold) 1-4 h post exercise. Myostatin was suppressed (3.6-

fold; p<0.05) 8-12 h post RUN. The cytokines exhibited a biphasic

response, with immediate elevation (p<0.05) of IL-6, IL-8, and

TNFalpha, followed by a second elevation (p<0.05) 2-24 h post

exercise.

In general, the timing of the gene induction indicated early

elevation of proteolytic genes, followed by prolonged elevation of

cytokines and suppression of myostatin. These data provide basic

information for the timing of human muscle biopsy samples for gene

expression studies involving exercise. Furthermore, this information

suggests a greater induction of proteolytic genes following RUN as

compared to RE. Key words: MuRF-1, atrogin-1, Exercise.