[Oxidative damage to the endoplasmic reticulum stress pathway of apoptosis-related molecules expression in MIN6 cell]

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Oxidative stress is implicated in pancreatic beta-cell dysfunction.
• Endoplasmic reticulum (ER) stress is a key cellular response to various insults, including oxidative damage.
• The JNK signaling pathway plays a critical role in mediating apoptosis.

Purpose of the Study:

• To investigate the role of oxidative damage induced by tert-butyl hydrogen peroxide (t-BHP) in pancreatic islet beta-cell apoptosis.
• To elucidate the involvement of the ER stress-JNK pathway in t-BHP-induced beta-cell apoptosis in vitro.
• To analyze the expression of apoptosis-related molecules within this pathway.

Main Methods:

• Mouse insulinoma (MIN6) cells were treated with varying concentrations (0-400 μmol/L) and durations (0-8 h) of t-BHP to induce apoptosis.
• Cell viability was assessed using CCK-8 assay.
• Apoptosis rates were determined by flow cytometry (Annexin-V-FITC-PI staining).
• Caspase-3 activity was measured using a commercial assay kit.
• Western blotting was employed to detect the expression of ER stress markers (IRE1α) and apoptosis pathway proteins (JNK, P-JNK, Caspase-3).

Main Results:

• t-BHP exposure significantly reduced MIN6 cell viability in a dose-dependent manner.
• Caspase-3 activity was significantly altered at t-BHP concentrations ≥ 25 μmol/L and exposure times ≥ 1 hour.
• Increased t-BHP concentration and prolonged exposure led to significantly elevated expression of ER stress protein IRE1α, phosphorylated JNK (P-JNK), and active Caspase-3.

Conclusions:

• t-BHP induces oxidative damage, leading to endoplasmic reticulum stress and apoptosis in MIN6 cells.
• The observed apoptosis is mediated through the ER stress-JNK signaling pathway.
• The expression of molecules involved in ER stress and apoptosis is modulated in a dose- and time-dependent manner by t-BHP exposure.