Regulation of oxidative enzyme activity and eukaryotic elongation factor 2 in human skeletal muscle: influence of gender and exercise.
OBJECTIVE
To investigate gender-related differences in the responses of oxidative enzymes and eukaryotic elongation factor-2 (eEF2) to exercise.


METHODS
The influence of exercise (90 min, 60%VO(2peak)) on citrate synthase (CS) and beta-hydroxyacyl-CoA dehydrogenase (HAD) activity and mRNA content, together with eEF2 expression and phosphorylation at rest, were assessed in skeletal muscle of untrained (UT) and endurance trained (ET) females and males.


RESULTS
Citrate synthase and HAD mRNA were higher in females than in males (27% and 48%, respectively, P < 0.05) whereas CS and HAD activity did not differ between females and males (NS). In females only, CS activity was enhanced (P < 0.05) by 90 min exercise. Resting CS mRNA content did not differ between UT and ET but, nevertheless, CS activity was 56% higher in ET than in UT volunteers (P < 0.001). HAD mRNA and activity were not influenced by training status (NS). In UT, CS mRNA was enhanced 37% (P < 0.05) by exercise whereas exercise did not change CS mRNA in ET (NS). eEF2 expression was 31% higher (P < 0.05) and eEF2 Thr56 phosphorylation (which leads to translation inhibition) was 24% lower (P < 0.05) in females than in males. eEF2 expression and phosphorylation were unaffected by training status (NS).


CONCLUSIONS
Basal transcriptional, translational, and/or post-translational control of CS and HAD seems to be gender-dependent. Also, gender differences in translation and/or post-translational protein modification of CS occur during exercise. Accordingly, the potential for peptide-chain elongation, based on eEF2 expression and phosphorylation, appears to be higher in females than in males.
Roepstorff
C
C
The Copenhagen Muscle Research Centre, Department of Human Physiology, Institute of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark. croepstorff@ifi.ku.dk
Schjerling
P
P
Vistisen
B
B
Madsen
M
M
Steffensen
C H
CH
Rider
M H
MH
Kiens
B
B
D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000378:metabolism*; D000328:Adult; D002950:Citrate (si)-Synthase / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000502:physiology; D020652:Peptide Elongation Factor 2 / Q000378:metabolism*; D010766:Phosphorylation; D010807:Physical Endurance / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D012737:Sex Factors
D020652:Peptide Elongation Factor 2; D012333:RNA, Messenger; D015094:3-Hydroxyacyl CoA Dehydrogenases; D002950:Citrate (si)-Synthase; D010100:Oxygen