Protein kinase B/Akt prevents fatty acid-induced apoptosis in pancreatic beta-cells (INS-1)

J Biol Chem. 2002 Dec 20;277(51):49676-84. doi: 10.1074/jbc.M208756200. Epub 2002 Oct 21.


Free fatty acids (FFA) have been reported to reduce pancreatic beta-cell mitogenesis and to increase apoptosis. Here we show that the FFA, oleic acid, increased apoptosis 16-fold in the pancreatic beta-cell line, INS-1, over a 18-h period as assessed by Hoechst 33342/propidium iodide staining and caspase-3 and -9 activation, with negligible necrosis. A parallel analysis of the phosphorylation activation of protein kinase B (PKB) showed this was reduced in the presence of FFA that correlated with the incidence of apoptosis. At stimulatory 15 mm glucose and/or in the added presence of insulin-like growth factor 1, FFA-induced beta-cell apoptosis was lessened compared with that at a basal 5 mm glucose. However, most strikingly, adenoviral mediated expression of a constitutively active PKB, but not a "kinase-dead" PKB variant, essentially prevented FFA-induced beta-cell apoptosis under all glucose/insulin-like growth factor 1 conditions. Further analysis of pro-apoptotic downstream targets of PKB, implicated a role for PKB-mediated phosphorylation inhibition of glycogen synthase kinase-3alpha/beta and the forkhead transcription factor, FoxO1, in protection of FFA-induced beta-cell apoptosis. In addition, down-regulation of the pro-apoptotic tumor suppressor protein, p53, via PKB-mediated phosphorylation of MDM2 might also play a role in partially protecting beta-cells from FFA-induced apoptosis. Adenoviral mediated expression of wild type p53 potentiated FFA-induced beta-cell apoptosis, whereas expression of a dominant negative p53 partly inhibited beta-cell apoptosis by approximately 50%. Hence, these data demonstrate that PKB activation plays an important role in promoting pancreatic beta-cell survival in part via inhibition of the pro-apoptotic proteins glycogen synthase kinase-3alpha/beta, FoxO1, and p53. This, in turn, provides novel insight into the mechanisms involved in FFA-induced beta-cell apoptosis.

Publication types

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

MeSH terms

  • Adenoviridae / genetics
  • Animals
  • Apoptosis*
  • Caspase 3
  • Caspase 9
  • Caspases / metabolism
  • Cell Survival
  • Dose-Response Relationship, Drug
  • Down-Regulation
  • Enzyme Activation
  • Fatty Acids / pharmacology*
  • Forkhead Box Protein O1
  • Forkhead Transcription Factors
  • Glucose / metabolism
  • Glucose / pharmacology
  • Immunoblotting
  • Insulin-Like Growth Factor I / metabolism
  • Islets of Langerhans / pathology*
  • Necrosis
  • Phosphorylation
  • Protein Binding
  • Protein Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-akt
  • Rats
  • Signal Transduction
  • Transcription Factors / metabolism
  • Tumor Suppressor Protein p53 / metabolism


  • Fatty Acids
  • Forkhead Box Protein O1
  • Forkhead Transcription Factors
  • Foxo1 protein, mouse
  • Proto-Oncogene Proteins
  • Transcription Factors
  • Tumor Suppressor Protein p53
  • Insulin-Like Growth Factor I
  • Akt1 protein, rat
  • Protein Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Casp3 protein, mouse
  • Casp3 protein, rat
  • Casp9 protein, mouse
  • Casp9 protein, rat
  • Caspase 3
  • Caspase 9
  • Caspases
  • Glucose