Autophagy plays a protective role in endoplasmic reticulum stress-mediated pancreatic β cell death

Autophagy. 2012 Dec;8(12):1757-68. doi: 10.4161/auto.21994. Epub 2012 Sep 5.

Abstract

There is a growing evidence of the role of autophagy in pancreatic β cell homeostasis. During development of type 2 diabetes, β cells are required to supply the increased demand of insulin. In such a stage, β cells have to address high ER stress conditions that could lead to abnormal insulin secretion, and ultimately, β cell death and overt diabetes. In this study, we used insulin secretion-deficient β cells derived from fetal mice. These cells present an increased accumulation of polyubiquitinated protein aggregates and LC3B-positive puncta, when compared with insulinoma-derived β cell lines. We found that insulin secretion deficiency renders these cells hypersensitive to endoplasmic reticulum (ER) stress-mediated cell death. Chemical or shRNA-mediated inhibition of autophagy increased β cell death under ER stress. On the other hand, rapamycin treatment increased both autophagy and cell survival under ER stress. Insulin secretion-deficient β cells showed a marked reduction of the antiapoptotic protein BCL2, together with increased BAX expression and ERN1 hyperactivation upon ER stress induction. These results showed how insulin secretion deficiency in β cells may be contributing to ER stress-mediated cell death, and in this regard, we showed how the autophagic response plays a prosurvival role.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagy* / drug effects
  • Cell Line
  • Cell Lineage / drug effects
  • Cytoprotection* / drug effects
  • Endoplasmic Reticulum Stress* / drug effects
  • HEK293 Cells
  • Humans
  • Insulin / metabolism
  • Insulin Secretion
  • Insulin-Secreting Cells / metabolism
  • Insulin-Secreting Cells / pathology*
  • Insulin-Secreting Cells / ultrastructure
  • Mechanistic Target of Rapamycin Complex 1
  • Mice
  • Multiprotein Complexes
  • Protein Structure, Quaternary
  • Proteins / metabolism
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Sirolimus / pharmacology
  • TOR Serine-Threonine Kinases
  • Unfolded Protein Response / drug effects

Substances

  • Insulin
  • Multiprotein Complexes
  • Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Mechanistic Target of Rapamycin Complex 1
  • TOR Serine-Threonine Kinases
  • Sirolimus