Glucocorticoid effects on glucose transport and transporter gene expression in L6 muscle cells.
We questioned whether glucocorticoids alter the known potent effect of serum to increase glucose transport and GLUT-1 expression in cultured L6 myotubes. Myotubes were exposed to serum-free medium for 24h in the presence or absence of 300 nM dexamethasone and subsequently treated for 8h with 10% serum or serum free medium in the continued presence or absence of the glucocorticoid. Dexamethasone did not effect the serum-induced increase in GLUT-1 mRNA. However, dexamethasone increased GLUT-1 mRNA 2-3 fold versus the absence of dexamethasone after serum withdrawal. Dexamethasone also resulted in higher GLUT-1 protein levels and ameliorated the loss of glucose transport activity seen after serum withdrawal.
Sivitz
W I
WI
Department of Internal Medicine, University of Iowa School of Medicine, Iowa City 52246.
Pasley
A M
AM
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002460:Cell Line; D003470:Culture Media; D016895:Culture Media, Serum-Free; D003847:Deoxyglucose / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D015870:Gene Expression / Q000187:drug effects*; D005947:Glucose / Q000378:metabolism*; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D015151:Immunoblotting; D007700:Kinetics; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis* / Q000302:isolation & purification; D009124:Muscle Proteins; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis
D003470:Culture Media; D016895:Culture Media, Serum-Free; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger; D003907:Dexamethasone; D003847:Deoxyglucose; D005947:Glucose