INS-1 세포에서 소포체스트레스에 대한 만성 고농도 포도당의 효과

Background: The highly developed endoplasmic reticulum (ER) structure is one of the characteristic features of pancreatic B-cells. Recent study showed that ER stress causes B-cell dysfunction. However, little is known about the effects of high glucose concentration on induction of ER stress in pancreatic B-cells. Therefore, this study was designed to evaluate whether exposure of high glucose concentration in rat insulinoma cell line, INS-1 cell induces ER stress and whether ER stress decreases insulin gene expression. Methods: The effect of 30 mM glucose on insulin expression and secretion in INS-1 cells was evaluated by Northern blot analysis and glucose-stimulated insulin secretion (GSIS). Cell viability was evaluated by XTT assay. The effect of 30 mM glucose on phosphorylation of eIF2 a and CHOP expression, which are markers of ER stress were evaluated by Western blot analysis. RT-PCR analysis was performed to determine whether high glucose concentration induces XBP-1 splicing. To investigate whether ER stress decreases insulin gene expression, the effect of tunicamycin on insulin mRNA expression was evaluated by Northern blot analysis. Results: The prolonged exposure of INS-1 cells with the 30 mM glucose concentration decreased insulin mRNA expression in a time dependent manner and impaired GSIS while did not influence on cell viability. 30 mM glucose increased phosphorylation of eIF2 a, XBP-1 splicing and CHOP expression in INS-1 cells. Tunicamycin-treated INS-1 increased XBP-1 splicing and decreased insulin mRNA expression in a dose dependent manner. Conclusion: This study showed that prolonged exposure of INS-1 with high glucose concentration induces ER stress and ER stress decreases insulin gene expression. Further studies about underlying molecular mechanism by which ER stress induces B-cell dysfunction are needed. mechanism by which ER stress induces B-cell dysfunction are needed.