Glucose transporter expression in skeletal muscle of endurance-trained individuals.
Two recently identified glucose transporters, GLUT8 and GLUT12, are expressed in human skeletal muscle and may be involved in insulin-mediated sugar transport.


OBJECTIVE
The purpose of this study was to measure GLUT8 and GLUT12 mRNA levels in endurance-trained versus sedentary individuals in an effort to determine the effect of repeated days of contractile activity on gene expression.


METHODS
GLUT 4, 8, and 12 mRNA were measured in biopsies from the vastus lateralis using quantitative real-time PCR in endurance-trained (N=16, age=22.0+/-0.9 yr, VO(2 max) (L.min(-1))=4.13+/-0.25) and sedentary (N=15, age=21.3+/-0.8 yr, VO(2 max) (L.min(-1))=3.21+/-0.24) subjects.


RESULTS
GLUT12 mRNA was lower (40+/-14%, P<0.05) in the exercise-trained compared with the sedentary subjects. There was no difference between groups in GLUT8 mRNA content. mRNA of the insulin-sensitive glucose transporter (GLUT4) was 78+/-27% (P<0.05) higher in skeletal muscle from endurance-trained compared with sedentary individuals.


CONCLUSIONS
These findings suggest an isoform-specific effect on the mRNA of the glucose transporters in human skeletal muscle with repeated days of contractile activity.
Seki
Yoshinori
Y
Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Berggren
Jason R
JR
Houmard
Joseph A
JA
Charron
Maureen J
MJ
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D005080:Exercise Test; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics; D051246:Glucose Transport Proteins, Facilitative / Q000032:analysis* / Q000235:genetics; D051275:Glucose Transporter Type 4 / Q000032:analysis / Q000235:genetics; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000032:analysis* / Q000235:genetics; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology*; D020033:Protein Isoforms / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D012420:Running / Q000502:physiology
D001786:Blood Glucose; D051246:Glucose Transport Proteins, Facilitative; D051275:Glucose Transporter Type 4; D007328:Insulin; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; C449579:SLC2A12 protein, human; C495692:SLC2A4 protein, human; C405325:SLC2A8 protein, human