Pancreatic β‑cell apoptosis in type 2 diabetes is related to post‑translational modifications of p53 (Review).

Abstract

Pancreatic β‑cells are the only cells that synthesize insulin to regulate blood glucose levels. Various conditions can affect the mass of pancreatic β‑cells and decrease insulin levels. Diabetes mellitus is a disease characterized by insulin resistance and chronic hyperglycemia, mainly due to the loss of pancreatic β‑cells caused by an increase in the rate of apoptosis. Additionally, hyperglycemia has a toxic effect on β‑cells. Although the precise mechanism of glucotoxicity is not fully understood, several mechanisms have been proposed. The most prominent changes are increases in reactive oxygen species, the loss of mitochondrial membrane potential and the activation of the intrinsic pathway of apoptosis due to p53. The present review analyzed the location of p53 in the cytoplasm, mitochondria and nucleus in terms of post‑translational modifications, including phosphorylation, O‑GlcNAcylation and poly‑ADP‑ribosylation, under hyperglycemic conditions. These modifications protect p53 from degradation by the proteasome and, in turn, enable it to regulate the intrinsic pathway of apoptosis through the regulation of anti‑apoptotic and pro‑apoptotic elements. Degradation of p53 occurs in the proteasome and depends on its ubiquitination by Mdm2. Understanding the mechanisms that activate the death of pancreatic β‑cells will allow the proposal of treatment alternatives to prevent the decrease in pancreatic β‑cells.