The transcription factor SREBP-1c is instrumental in the development of beta-cell dysfunction

J Biol Chem. 2003 May 9;278(19):16622-9. doi: 10.1074/jbc.M212488200. Epub 2003 Feb 24.

Abstract

Accumulation of lipids in non-adipose tissues is often associated with Type 2 diabetes and its complications. Elevated expression of the lipogenic transcription factor, sterol regulatory element binding protein-1c (SREBP-1c), has been demonstrated in islets and liver of diabetic animals. To elucidate the molecular mechanisms underlying SREBP-1c-induced beta-cell dysfunction, we employed the Tet-On inducible system to achieve tightly controlled and conditional expression of the nuclear active form of SREBP-1c (naSREBP-1c) in INS-1 cells. Controlled expression of naSREBP-1c induced massive accumulation of lipid droplets and blunted nutrient-stimulated insulin secretion in INS-1 cells. K(+)-evoked insulin exocytosis was unaltered. Quantification of the gene expression profile in this INS-1 stable clone revealed that naSREBP-1c induced beta-cell dysfunction by targeting multiple genes dedicated to carbohydrate metabolism, lipid biosynthesis, cell growth, and apoptosis. naSREBP-1c elicits cell growth-arrest and eventually apoptosis. We also found that the SREBP-1c processing in beta-cells was irresponsive to acute stimulation of glucose and insulin, which was distinct from that in lipogenic tissues. However, 2-day exposure to these agents promoted SREBP-1c processing. Therefore, the SREBP-1c maturation could be implicated in the pathogenesis of beta-cell glucolipotoxicity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CCAAT-Enhancer-Binding Proteins / biosynthesis*
  • CCAAT-Enhancer-Binding Proteins / physiology
  • Clone Cells
  • DNA-Binding Proteins / biosynthesis*
  • DNA-Binding Proteins / physiology
  • Diabetes Mellitus, Type 2 / etiology
  • Diabetes Mellitus, Type 2 / metabolism
  • Gene Expression Regulation / drug effects
  • Gene Expression Regulation / physiology
  • Glucose / metabolism
  • Glucose / pharmacology
  • Hypoglycemic Agents / pharmacology
  • Insulin / metabolism
  • Insulin / pharmacology
  • Islets of Langerhans / metabolism
  • Islets of Langerhans / physiopathology*
  • Protein Processing, Post-Translational / drug effects
  • Protein Processing, Post-Translational / physiology*
  • Rats
  • Sterol Regulatory Element Binding Protein 1
  • Transcription Factors / physiology

Substances

  • CCAAT-Enhancer-Binding Proteins
  • DNA-Binding Proteins
  • Hypoglycemic Agents
  • Insulin
  • Srebf1 protein, rat
  • Sterol Regulatory Element Binding Protein 1
  • Transcription Factors
  • Glucose