The apoptosis inhibitor ARC alleviates the ER stress response to promote β-cell survival

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Wendy M McKimpson1, Jeremy Weinberger, Lech Czerski

  • 1Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA.

Diabetes
|August 31, 2012
PubMed

Insights

Apoptosis repressor with caspase recruitment domain (ARC) protects pancreatic beta cells from death. ARC inhibits apoptosis by suppressing the endoplasmic reticulum stress response, offering a new target for type 2 diabetes therapies.

Area of Science:

  • Endocrinology
  • Cell Biology
  • Molecular Biology

Background:

  • Type 2 diabetes is characterized by insulin resistance and beta-cell failure, leading to insufficient insulin secretion.
  • Beta-cell loss through apoptosis is a critical factor in the progression of type 2 diabetes.
  • Apoptosis repressor with caspase recruitment domain (ARC) is a known inhibitor of apoptosis in various cell types, including neurons and myocytes.

Purpose of the Study:

  • To investigate the role of ARC in pancreatic beta-cell survival and apoptosis.
  • To determine if ARC expression is altered in beta-cells and if it influences apoptosis induced by common beta-cell stressors.
  • To elucidate the mechanism by which ARC might protect beta-cells from apoptosis.

Main Methods:

  • Utilized genetic gain- and loss-of-function approaches in beta-cells.
  • Examined ARC protein abundance in mouse and human pancreatic beta-cells.
  • Assessed the impact of ARC on apoptosis induced by endoplasmic reticulum (ER) stressors (tunicamycin, thapsigargin) and palmitate.
  • Investigated ARC's effect on the ER stress response pathway, including PERK, IRE1α, and CHOP.
  • Studied the interaction between ARC and CHOP in palmitate-induced apoptosis.

Main Results:

  • ARC protein is highly abundant in pancreatic beta-cells (>99.5% in mouse, 73% in human).
  • ARC significantly inhibits beta-cell apoptosis induced by ER stressors and palmitate.
  • ARC suppresses the ER stress response pathway, acting downstream of PERK and IRE1α to reduce CHOP induction.
  • Depletion of ARC exacerbates palmitate-induced beta-cell apoptosis, an effect rescued by CHOP deletion.

Conclusions:

  • ARC is a previously unrecognized inhibitor of apoptosis in pancreatic beta-cells.
  • ARC protects beta-cells by suppressing the ER stress response, specifically CHOP induction.
  • Targeting ARC may represent a novel therapeutic strategy for preserving beta-cell function in type 2 diabetes.

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