Protein kinase B is expressed in pancreatic beta cells and activated upon stimulation with insulin-like growth factor I

Biochem Biophys Res Commun. 1998 Sep 8;250(1):181-6. doi: 10.1006/bbrc.1998.9166.

Abstract

Protein kinase B (PKB) is involved in signaling to a multitude of important cellular events and is activated by insulin and growth factors, including insulin-like growth factor I (IGF-I). We show here expression of PKB in pancreatic islets and in the beta cell lines HIT-T15, INS-1, and RINm5F. Expression of PKB mRNA and the presence of PKB isoforms (alpha, beta, and gamma) were assessed by Northern blot analysis and RT-PCR, respectively. Antibodies recognizing different parts of PKB isoforms were employed to demonstrate PKB protein expression by immunoblot analysis. By use of immunohistochemistry in rat and mouse pancreatic tissue sections, PKB was localized to predominantly beta cells. Regulation of PKB was examined in INS-1 and RINm5F cells; upon stimulation with IGF-I (5-10 min), PKB was phosphorylated and activated (approximately 3-fold) by a wortmannin-sensitive mechanism, indicating involvement of phosphatidylinositol-3 kinase. The possible participation of PKB in signal transduction pathways modulating cAMP-dependent insulin secretion and in proliferation of beta cells is discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Enzyme Activation
  • Immunohistochemistry
  • Insulin-Like Growth Factor I / pharmacology*
  • Islets of Langerhans / drug effects*
  • Islets of Langerhans / enzymology
  • Mice
  • Protein-Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-akt
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction
  • Tumor Cells, Cultured

Substances

  • Proto-Oncogene Proteins
  • RNA, Messenger
  • Insulin-Like Growth Factor I
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt