Ghrelin Improves Glucolipotoxicity-Induced Pancreatic β-Cellular Dysfunction and Apoptosis by Inhibiting Endoplasmic Reticulum Stress-Induced IRE1/JNK Pathway.

Abstract

Glucose and fatty acid overload-induced glucolipid toxicity of pancreatic β-cells is associated with the development of diabetes. Endoplasmic reticulum stress (ERS) plays an essential role in this process. Ghrelin, a peptide secreted by the pancreas, negatively correlates with oxidative stress. The study aimed to investigate ghrelin's role in glycolipid-induced β-cell dysfunction and its possible mechanism. Mouse insulinoma β-cell, NIT-1 cells, were stimulated with high fat and high glucose to induce glucolipid toxicity. High fat and high glucose-induced NIT-1 cells were treated with acylated ghrelin (AG) or [d-Lys3]-growth hormone releasing peptide (GHRP)-6. Flow cytometry and Cell Counting Kit-8 (CCK-8) assay were performed to assess apoptosis and cell viability. The protein expression related to apoptosis, inositol-requiring kinase 1 (IRE1)/c-Jun N-terminal kinase (JNK) signaling, and ERS were investigated using western blot. Enzyme-linked immunosorbent assay (ELISA) was adopted to examine insulin's synthesis and secretion levels. Ghrelin treatment improved cell viability while inhibiting cell glucolipotoxicity-induced NIT-1 cell apoptosis. Ghrelin can promote the synthesis and secretion of insulin in NIT-1 cells. Mechanistically, ghrelin attenuates ERS and inhibits the IRE1/JNK signaling pathway in NIT-1 cells induced by glucolipotoxicity. Ghrelin improves β-cellular dysfunction induced by glucolipotoxicity by inhibiting the IRE1/JNK pathway induced by ERS. It could be an effective treatment for β-cellular dysfunction.