PDTC Prevents The Decrease Of Insulin Gene Expression Induced By Elevated Glucose Concentrations In INS-1 Cell

OBJECTIVETo study the impact of elevated glucose on the expression of insulin gene and insulin transcript factors PDX-1 and MafA; and to clarify the mechanism of the protection of PDTC(an inhibitor of NF-κB) on glucotoxicity.METHODSINS-1 cells were cultured in RPM1-1640 media containing 11.1 mmol/L glucose. Cells were then cultured for 48 hours in medias containing 4.0 mmol/L glucose, 16.7 mmol/L glucose, 16.7 mmol/L glucose + 50umol/L PDTC respectively. The mRNA levels of insulin, PDX-1 and MafA were determined by real-time PCR.RESULTSINS-1 cells incubated in 16.7 mmol/L glucose for 48h decreased 64.9%(P<0.05) in insulin mRNA levels compared with INS-1 cells incubated in 4.0 mmol/L glucose; PDX-1 mRNA levels decreased 82.3%(P<0.01); MafA mRNA levels decreased 80.9%(P<0.01). INS-1 cells incubated in 16.7 mmol/L glucose + 50umol/L PDTC for 48h yielded up to a 6.67-fold(P<0.05)increase in insulin mRNA levels compared with INS-1 cells incubated in 16.7 mmol/L glucose; PDX-1 mRNA levels increased 7.52 fold(P<0.05); MafA mRNA levels increased 5.70 fold(P<0.01). There was no difference between cells incubated in 4.0mmol/L glucose and 16.7 mmol/L glucose + 50umol/L PDTC (P>0.05).CONCLUSIONThese data suggested that elevation in glucose concentrations leds to a decrease in insulin and insulin transcript factors PDX-1 and MafA mRNA levels in INS-1 cells. PDTC, an inhibitor of NF-κB, could attenuate these impact of elevated glucose. We concluded that elevated glucose(glucotoxicity) can reduce the expression of insulin gene transcript factors PDX-1 and MafA through activating NF-κB, and then decrease the expression of insulin.