Gender Differences in Stress Protein and Actin Expression in Murine Skeletal Muscle Following Downhill Running

Prianka Patel
Smith College

Stress proteins serve many homeostatic roles in cellular protein metabolism such as intracellular protein transport, protein renaturation and protein folding. Yet little is known about these chaperones in vivo. We have studied the protein expression of both the stress proteins HSP60 and HSP90 and the contractile protein actin in the biceps brachii muscle following a single bout of downhill running in exercise naïve male and female mice. The mice ran downhill at a decline (-15º) at 25 m min-1 for 15 minutes. This was there first and only exercise bout ever. Biceps were excised at various time points following the exercise, extracted for total protein, separated on SDS-polyacrylamide gels, immunoblotted and probed with monoclonal antibodies to the stress proteins and actin. The resulting blots were analyzed quantitatively. Significant changes are defined as p < 0.05 relative to control (-1 hr). One significant increase was observed in the males, HSP60 at 1 week, whereas the females exhibited significant elevations in both HSP60 and HSP90 at 12 hours following the exercise. For actin, however, no significant change in expression was observed in the females, whereas in the males a significant increase was seen immediately post-exercise followed by decreases at 3, 6, 12 and 72 hours post-exercise. The stress protein and actin expression responses following exercise differ between the genders. Generally, females had earlier and smaller stress protein responses than males, whereas females exhibited no actin response while males dramatically decreased their actin content.