MODY Signal Pathway in the Endoplasmic Reticulum Stress and the Role of Nkx6.1 in the Glucolipotoxicity of INS-1-3 Cells

Abstract

Metabolic disturbances induce endoplasmic reticulum stress (ERS) in pancreatic beta cells. This study aims to investigate whether a common pathway exists in the ERS induced by various chemicals, including high levels of glucose and palmitate. ERS in INS-1-3 cells was induced by exposure cells to thapsigargin (TG), tunicamycin (TM) or palmitic acid (PA) +high glucose (HG). Digital gene expression (DGE) profiling technique was used to detect differentially expressed genes. The profile of gene expression was detected by gene oncology (GO) function and pathway enrichment analysis. On the basis of DGE results, Nkx6.1 over-expression was established in INS-1-3 cell lines by lentivirus infection to explore the importance of the findings. Real time reverse transcription polymerase chain reaction (RT-PCR) was used to verify the expression changes of key genes. Cell viability was measured by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. And the apoptosis was detected by flow cytometry. Glucose stimulates insulin secretion (GSIS) was used to measure the INS-1-3 cell function. DGE demonstrated that there were 135, 57 and 74 differentially expressed genes in TM, TG and HG+PA groups, respectively. Genes that were differentially expressed were enriched to endoplasmic reticulum stress, antigen processing and presentation, and protein export pathways, and surprisingly, the maturity onset diabetes of the young (MODY) pathway. Nkx6.1 is a common abnormal-expressed gene in MODY signaling pathway among TM, TG and HG+PA groups. Apoptosis was ameliorated by 45.4% and proliferation was increased by 40.9% in the Nkx6.1 over-expression cells exposed to high level of glucose and palmitate. At the same time, both basal and glucose stimulated insulin secretion increased by 2.09 and 1.82 folds, respectively. ERS changed the expression of MODY pathway genes. Over-expression of Nkx6.1 protected the INS-1-3 cells from glucolipotoxicity. Disclosure Y. Dong: None. Y. Li: None. J. Xiao: None.