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Activated PKR inhibits pancreatic β-cell proliferation through sumoylation-dependent stabilization of P53

Ying Song1, XiaoMeng Wan2, LiLi Gao2

  • 1Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, PR China.

Molecular Immunology
|October 9, 2015
PubMed

Insights

Double-stranded RNA-dependent protein kinase (PKR) activation in pancreatic cells inhibits proliferation by stabilizing P53. This occurs via a ceramide/PKR/Ubc9 pathway, crucial for type 2 diabetes development.

Area of Science:

  • Molecular Biology
  • Endocrinology
  • Cell Biology

Background:

  • Double-stranded RNA-dependent protein kinase (PKR) is implicated in type 2 diabetes, affecting insulin resistance and pancreatic beta-cell proliferation.
  • Activated PKR inhibits beta-cell proliferation, partly via P53 accumulation, but the precise mechanism is unclear.

Purpose of the Study:

  • To elucidate the molecular mechanisms by which PKR activation leads to P53 upregulation in pancreatic beta-cells.
  • To investigate the role of sumoylation and ceramide signaling in PKR-mediated P53 stabilization.

Main Methods:

  • Activation of PKR in beta-cells using a novel compound (BEPP).
  • Analysis of P53 and Ubc9 interactions and sumoylation.
  • Investigating the role of ceramide in PKR activation triggered by glucolipotoxicity and TNFα.

Main Results:

  • PKR activation by BEPP in beta-cells upregulates P53 through sumoylation-dependent stability.
  • Activated PKR interacts with Ubc9, a key enzyme in sumoylation.
  • Ceramide signaling is essential for PKR activation by glucolipotoxicity/TNFα and subsequent P53 stabilization.

Conclusions:

  • Glucolipotoxicity and pro-inflammatory cytokines promote P53 sumoylation-dependent stability via the ceramide/PKR/Ubc9 pathway.
  • This pathway contributes to pancreatic beta-cell proliferation inhibition in type 2 diabetes.
  • The findings reveal a novel mechanism linking cellular stress to beta-cell dysfunction in diabetes.
Keywords:
CeramideP53PKRPancreatic β-cellProliferationSumoylation

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