Modulation of Unfolded Protein Response Restores Survival and Function of β-Cells Exposed to the Endocrine Disruptor Bisphenol A

Abstract

Diabetes is a metabolic disease that currently affects nearly half a billion people worldwide. β-cells dysfunction is one of the main causes of diabetes. Exposure to endocrine-disrupting chemicals is correlated with increased diabetes incidence. We hypothesized that treatment with bisphenol A (BPA) induces endoplasmic reticulum (ER) stress that activates the unfolded protein response (UPR), leading to impaired function of the β-cells, which over time, can cause diabetes. In this study, we aimed to evaluate UPR pathways activation under BPA treatment in β-cells and possible recovery of ER homeostasis. MIN6 cells (mouse insulinoma cell line) and isolated pancreatic islets from NOR (non-obese diabetes resistant) mice were treated with BPA. We analyzed the impact of BPA on β-cell viability, the architecture of the early secretory pathway, the synthesis and processing of insulin and the activation of UPR sensors and effectors. We found that the addition of the chemical chaperone TUDCA rescues the deleterious effects of BPA, resulting in improved viability, morphology and function of the β-cells. In conclusion, we propose that modulators of UPR can be used as therapeutic interventions targeted towards regaining β-cells homeostasis.

Keywords

• unfolded protein response
• diabetes
• endocrine disruptor
• bisphenol A
• insulin granules