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Visualization of Endogenous Mitophagy Complexes In Situ in Human Pancreatic Beta Cells Utilizing Proximity Ligation Assay
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Visualization of Endogenous Mitophagy Complexes In Situ in Human Pancreatic Beta Cells Utilizing Proximity Ligation Assay

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Autophagy regulates pancreatic beta cell death in response to Pdx1 deficiency and nutrient deprivation

Kei Fujimoto1, Piia T Hanson, Hung Tran

  • 1Division of Endocrinology, Metabolism and Lipid Research, Department of Internal Medicine, Washington University School of Medicine/Barnes-Jewish Hospital, St. Louis, Missouri 63110, USA.

The Journal of Biological Chemistry
|August 6, 2009
PubMed

Insights

Increased autophagy contributes to pancreatic beta cell death in Pdx1 deficiency and nutrient deprivation. Inhibiting autophagy may protect beta cells, suggesting it as a therapeutic target for diabetes.

Area of Science:

  • Cell Biology
  • Endocrinology
  • Metabolic Diseases

Background:

  • Autophagy is a cellular degradation process with implications in various cell death pathways.
  • Pancreatic beta cells are crucial for insulin secretion and maintaining glucose homeostasis.
  • Dysfunction in beta cells is central to the pathogenesis of diabetes mellitus.

Purpose of the Study:

  • To investigate the role of macroautophagy (autophagy) in pancreatic beta cell death.
  • To determine if inhibiting autophagy can protect beta cells from death induced by Pdx1 deficiency or nutrient deprivation.
  • To explore the therapeutic potential of targeting autophagy in diabetes.

Main Methods:

  • Utilized Pdx1(+/-) mice and MIN6 cells to study Pdx1 deficiency-induced beta cell death and autophagy.
  • Employed lentiviral vectors for small hairpin RNA-mediated Pdx1 knockdown in MIN6 cells.
  • Investigated the effects of autophagy inhibition using pharmacological inhibitors and genetic models (Becn1(+/-) mice).
  • Assessed beta cell function, mass, and glucose tolerance under various conditions, including nutrient deprivation and high-fat diet.

Main Results:

  • Increased autophagy was observed in pancreatic islets of Pdx1(+/-) mice and in MIN6 cells with Pdx1 deficiency.
  • Pdx1 deficiency led to MIN6 cell death, preceded by evident autophagy; autophagy inhibition delayed this death.
  • Nutrient deprivation enhanced autophagy in MIN6 cells and islets, and its inhibition partly prevented starvation-induced cell death.
  • In vivo, reduced autophagy (Pdx1(+/-) Becn1(+/-) mice) initially preserved beta cell function and mass on a high-fat diet, but this effect diminished over time.

Conclusions:

  • Enhanced autophagy contributes significantly to pancreatic beta cell death under conditions of Pdx1 deficiency and nutrient/amino acid starvation.
  • Inhibition of autophagy demonstrates a protective effect on beta cells, delaying cell death and preserving function in specific contexts.
  • Autophagy represents a potential therapeutic target for interventions aimed at preventing or mitigating pancreatic beta cell death in diabetes and related metabolic disorders.

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