PKC-zeta mediates insulin effects on glucose transport in cultured preadipocyte-derived human adipocytes

J Clin Endocrinol Metab. 2002 Feb;87(2):716-23. doi: 10.1210/jcem.87.2.8252.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 3T3 Cells
  • Adipocytes / metabolism*
  • Adult
  • Animals
  • Biological Transport / drug effects
  • Cell Line
  • Female
  • Glucose / metabolism*
  • Humans
  • Insulin / pharmacology*
  • Mice
  • Muscle Fibers, Skeletal / metabolism
  • Protein Kinase C / physiology*
  • Stem Cells / metabolism*


  • Insulin
  • protein kinase C zeta
  • Protein Kinase C
  • Glucose