Exendin-4 protects oxidative stress-induced β-cell apoptosis through reduced JNK and GSK3β activity

Area of Science:

• Endocrinology
• Molecular Biology
• Diabetes Research

Background:

• Chronic hyperglycemia in type 2 diabetes causes oxidative stress, leading to beta-cell apoptosis and loss of function.
• Glucagon-like peptide-1 (GLP-1) is known to preserve beta-cell mass and insulin secretion, but its precise anti-apoptotic mechanisms are unclear.

Purpose of the Study:

• To investigate the protective mechanisms of GLP-1 against oxidative stress-induced apoptosis in pancreatic beta cells.
• To elucidate how GLP-1 receptor agonists modulate key signaling pathways involved in beta-cell survival.

Main Methods:

• Beta-cell lines and human islets were subjected to oxidative stress using hydrogen peroxide (H2O2).
• Pretreatment with Exendin-4 (Ex-4), a GLP-1 receptor agonist, was employed.
• Flow cytometry was used to quantify apoptosis.
• Western blotting assessed the activation of GSK3β, JNK phosphorylation, and caspase-9/-3.
• Insulin2 mRNA expression and insulin secretion were measured.

Main Results:

• Ex-4 pretreatment significantly reduced oxidative stress-induced beta-cell apoptosis by 41.7%.
• Ex-4 treatment decreased the activation of GSK3β, JNK phosphorylation, and caspase-9/-3.
• Ex-4 administration restored insulin2 mRNA expression in beta-cell lines and insulin secretion in human islets.

Conclusions:

• Exendin-4, a GLP-1 receptor agonist, effectively protects pancreatic beta cells from oxidative stress-induced apoptosis.
• The protective effect is mediated by inhibiting the JNK and GSK3β signaling pathways.
• These findings highlight GLP-1's potential therapeutic role in preserving beta-cell function in diabetes.