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FoxO1 protects against pancreatic beta cell failure through NeuroD and MafA induction

Yukari Ido Kitamura1, Tadahiro Kitamura, Jan-Philipp Kruse

  • 1Naomi Berrie Diabetes Center, Department of Medicine, Columbia University, New York, New York 10032, USA.

Cell Metabolism
|September 13, 2005
PubMed

Insights

Forkhead protein FoxO1 protects pancreatic beta cells from diabetes-induced oxidative stress. It forms a complex that activates key insulin gene transcription factors, preventing cell failure.

Area of Science:

  • Cell biology
  • Endocrinology
  • Molecular biology

Background:

  • Diabetes mellitus leads to pancreatic beta cell dysfunction and failure.
  • Hyperglycemia induces oxidative stress, termed 'glucose toxicity,' damaging beta cells.
  • Forkhead box protein O1 (FoxO1) is a key regulator of cellular stress responses.

Purpose of the Study:

  • To elucidate the protective mechanism of FoxO1 against hyperglycemia-induced oxidative stress in pancreatic beta cells.
  • To identify the molecular interactions and pathways regulated by FoxO1 in beta cell survival.
  • To investigate the role of FoxO1 acetylation in its stability and function.

Main Methods:

  • Utilized acetylation-defective and acetylation-mimicking FoxO1 mutants.
  • Investigated protein complex formation involving FoxO1, Pml, and Sirt1.
  • Assessed the impact of hyperglycemia on MafA expression in vivo.
  • Employed transgenic expression of constitutively nuclear FoxO1 in beta cells.

Main Results:

  • FoxO1 forms a complex with Pml and Sirt1, activating NeuroD and MafA transcription factors.
  • Acetylation of FoxO1 targets it to Pml, preventing its degradation.
  • Hyperglycemia suppresses MafA expression in vivo.
  • Transgenic FoxO1 expression prevents MafA inhibition and beta cell damage.

Conclusions:

  • FoxO1 protects beta cells against glucose toxicity via a Pml/Sirt1 complex that enhances insulin gene transcription.
  • FoxO1 acetylation is crucial for its stability and protective function.
  • This pathway links glucose signaling to beta cell protection from oxidative damage.

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