The transcription factor B-cell lymphoma (BCL)-6 modulates pancreatic {beta}-cell inflammatory responses

Endocrinology. 2011 Feb;152(2):447-56. doi: 10.1210/en.2010-0790. Epub 2010 Dec 29.

Abstract

Type 1 diabetes is a chronic autoimmune disease with a strong inflammatory component. We have previously shown that expression of the transcriptional repressor B-cell lymphoma (BCL)-6 is very low in pancreatic β-cells, which may favor prolonged proinflammatory responses after exposure to the cytokines IL-1β and interferon γ. Here we investigated whether cytokine-induced inflammation and apoptosis can be prevented in β-cells by BCL-6 expression using plasmid, prolactin, and adenoviral approaches. The induction of mild or abundant BCL-6 expression in β-cells by prolactin or an adenoviral BCL-6 expression construct, respectively, reduced cytokine-induced inflammatory responses in a dose-dependent manner through inhibition of nuclear factor-κB activation. BCL-6 decreased Fas and inducible nitric oxide synthase expression and nitric oxide production, but it inhibited the expression of the antiapoptotic proteins Bcl-2 and JunB while increasing the expression of the proapoptotic death protein 5. The net result of these opposite effects was an augmentation of β-cell apoptosis. In conclusion, BCL-6 expression tones down the unrestrained cytokine-induced proinflammatory response of β-cells but it also favors gene networks leading to apoptosis. This suggests that cytokine-induced proinflammatory and proapoptotic signals can be dissociated in β-cells. Further understanding of these pathways may open new possibilities to improve β-cell survival in early type 1 diabetes or after transplantation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Blotting, Western
  • Cell Line
  • Cell Survival / drug effects
  • Cell Survival / genetics
  • Colforsin / pharmacology
  • Cytokines / pharmacology
  • Exenatide
  • Fluorescent Antibody Technique
  • Insulin-Secreting Cells / cytology
  • Insulin-Secreting Cells / drug effects
  • Insulin-Secreting Cells / immunology*
  • Insulin-Secreting Cells / metabolism*
  • Male
  • NF-kappa B / genetics
  • Nitric Oxide Synthase Type II / genetics
  • Peptides / pharmacology
  • Polymerase Chain Reaction
  • Prolactin / pharmacology
  • Proto-Oncogene Proteins c-bcl-6 / genetics
  • Proto-Oncogene Proteins c-bcl-6 / metabolism*
  • Rats
  • Rats, Wistar
  • Venoms / pharmacology
  • fas Receptor / genetics

Substances

  • Cytokines
  • NF-kappa B
  • Peptides
  • Proto-Oncogene Proteins c-bcl-6
  • Venoms
  • fas Receptor
  • Colforsin
  • Prolactin
  • Exenatide
  • Nitric Oxide Synthase Type II