Inhibition of protein kinase CbetaII increases glucose uptake in 3T3-L1 adipocytes through elevated expression of glucose transporter 1 at the plasma membrane.
The mechanism via which diacylglycerol-sensitive protein kinase Cs (PKCs) stimulate glucose transport in insulin-sensitive tissues is poorly defined. Phorbol esters, such as phorbol-12-myristate-13-acetate (PMA), are potent activators of conventional and novel PKCs. Addition of PMA increases the rate of glucose uptake in many different cell systems. We attempted to investigate the mechanism via which PMA stimulates glucose transport in 3T3-L1 adipocytes in more detail. We observed a good correlation between the rate of disappearance of PKCbetaII during prolonged PMA treatment and the increase in glucose uptake. Moreover, inhibition of PKCbetaII with a specific myristoylated PKCbetaC2-4 peptide inhibitor significantly increased the rate of glucose transport. Western blot analysis demonstrated that both PMA treatment and incubation with the myristoylated PKCbetaC2-4 pseudosubstrate resulted in more glucose transporter (GLUT)-1 but not GLUT-4 at the plasma membrane. To our knowledge, we are the first to demonstrate that inactivation of PKC, most likely PKCbetaII, elevates glucose uptake in 3T3-L1 adipocytes. The observation that PKCbetaII influences the rate of glucose uptake through manipulation of GLUT-1 expression levels at the plasma membrane might reveal a yet unidentified regulatory mechanism involved in glucose homeostasis.
Bosch
Remko R
RR
Department of Chemical Endocrinology, University Medical Centre, 6500 HB Nijmegen, The Netherlands. R.Bosch@ace.umcn.nl
Bazuine
Merlijn
M
Wake
Michelle M
MM
Span
Paul N
PN
Olthaar
André J
AJ
Schürmann
Annette
A
Maassen
J Antonie
JA
Hermus
Ad R M M
AR
Willems
Peter H G M
PH
Sweep
C G J
CG
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000493:pharmacokinetics*; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D051379:Mice; D018716:Molecular Mimicry; D009004:Monosaccharide Transport Proteins / Q000187:drug effects / Q000378:metabolism*; D009124:Muscle Proteins; D009842:Oligopeptides / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000378:metabolism; D064546:Protein Kinase C beta; D019311:Staurosporine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004791:Enzyme Inhibitors; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007211:Indoles; D007527:Isoenzymes; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D009842:Oligopeptides; D010455:Peptides; C495678:Slc2a1 protein, mouse; C495693:Slc2a4 protein, mouse; C487010:myristoyl-seryl-leucyl-asparagyl-prolyl-glutamyl-tryptophyl-asparagyl-glutamyl-threonine; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D019311:Staurosporine; D005947:Glucose; D013755:Tetradecanoylphorbol Acetate; C064758:Ro 31-8220