PKC-zeta mediates insulin effects on glucose transport in cultured preadipocyte-derived human adipocytes.
Insulin-stimulated glucose transport is impaired in the early phases of type 2 diabetes mellitus. Studies in rodent cells suggest that atypical PKC (aPKC) isoforms (zeta, lamda, and iota) and PKB, and their upstream activators, PI3K and 3-phosphoinositide-dependent protein kinase-1 (PDK-1), play important roles in insulin-stimulated glucose transport. However, there is no information on requirements for aPKCs, PKB, or PDK-1 during insulin action in human cell types. Presently, by using preadipocyte-derived adipocytes, we were able to employ adenoviral gene transfer methods to critically examine these requirements in a human cell type. These adipocytes were found to contain PKC-zeta, rather than PKC-lamda/iota, as their major aPKC. Expression of kinase-inactive forms of PDK-1, PKC-zeta, and PKC-lamda (which functions interchangeably with PKC-zeta) as well as chemical inhibitors of PI 3-kinase and PKC-zeta/lamda, wortmannin and the cell-permeable myristoylated PKC-zeta pseudosubstrate, respectively, effectively inhibited insulin-stimulated glucose transport. In contrast, expression of a kinase-inactive, activation-resistant, triple alanine mutant form of PKB-alpha had little or no effect, and expression of wild-type and constitutively active PKC-zeta or PKC-lamda increased glucose transport. Our findings provide convincing evidence that aPKCs and upstream activators, PI 3-kinase and PDK-1, play important roles in insulin-stimulated glucose transport in preadipocyte-derived human adipocytes.
Bandyopadhyay
Gautam
G
J. A. Haley Veterans' Hospital Research Service and Department of Internal Medicine, University of South Florida College of Medicine, Tampa, Florida 33612, USA. rfarese@com1.med.usf.edu
Sajan
Mini P
MP
Kanoh
Yoshinori
Y
Standaert
Mary L
ML
Quon
Michael J
MJ
Lea-Currie
Rene
R
Sen
Anindita
A
Farese
Robert V
RV
D016475:3T3 Cells; D017667:Adipocytes / Q000378:metabolism*; D000328:Adult; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002460:Cell Line; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D011493:Protein Kinase C / Q000502:physiology*; D013234:Stem Cells / Q000378:metabolism*; D000099221:Protein Kinase C zeta
D005947:Glucose; D007328:Insulin; D011493:Protein Kinase C; D000099221:Protein Kinase C zeta