The Short Term Effect of Insulin on Proinsulin Gene Expression of HIT-T15 Insulinnoma Cells / 天津医药

ABSTRACT

Objective To investigate the short term effect of insulin on proinsulin gene expression of HIT-T15 insu-linnoma cells(pancreatic isletβ-cell). Methods The HIT-T15 cells were randomly divided into four groups.Blank Con-trol Group (LG)complete medium contain 1.4 mmol/L glucose. Control group (LGC)co-cultured nifedipine with medium in order to restain endogenous insulin release. Experimental group (LINS or HINS) add 0.5 U/L insulin or 5 U/L insulin on top of LGC. After being stimulated for 0, 30, 60, 90, 120 mins, proinsulin (PI) mRNA level were assessed by semi-quantitative RT-PCR. Insulin receptor substrate1 (IRS1) tyrosine phosphorylation was detected by immunocytochemistry. Results (1) Expression of PI was up regulated by both LINS and HINS, and peak at 60 mins. (2) After stimulation for 30 mins, the level of IRS1 tyrosine phosphorylation in the experimental group was significantly higher than control group, and the peak time be-tween LINS and HINS was different. (3) Between group of LG and LGC, the expression of PI mRNA and IRS1 tyrosine phos-phorylation show no difference. Conclusion Short term exogenous insulin stimulation can promote expression of proinsulin genes,which is concentration dependent. The expression and regulation of PI were related with IRS1 signal transduction.