Study On The Mechanism Of Pancreatic Microvascular Endothelial Cell Apoptosis Induced By Glycolipid Toxicity

Objective To investigate the effect of hyperglycemia on the apoptosis and proliferation of islet endothelial cell line (MS-1),and the protective effect and possible mechanism of GLP-1analogues on the endoplasmic reticulum stress pathway of apoptosis.Methods MS-1cells were treated with different concentrations of glucose (5.6mmol/L、25mmol/L and33.6mmol/L)and harvested at the indicated time (12h and24h). Then cells were pretreated with Exendin-4(100nmol/L)prior to treated with hyperglycemia.The apoptosis of each group was detected by FACS, cell proliferation was tested using3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT);GRP78、CHOP、caspase-3、caspase-12mRNA expression were examined by reverse transcription and polymerase chain reaction assay (RT-PCR), and the protein expression of GRP78、CHOP were examined by Western blot. The statistical significance was determined by Student’s t-test and one-way ANOVA.Results After treated with hyperglycemia for12h and24h, the apoptosis rate was obviously higher in25mmol/L and33.6mmol/L group than in5.6mmol/L group (p<0.05),while cell proliferation was significantly lower in25mmol/L and33.6mmol/L group than that in5.6mmol/L group (p<0.05); the mRNA level of CHOP、caspase-3、caspase-12mRNA and the protein level of CHOP were increased in a dose-dependent manner(p<0.05); the mRNA and protein level of GRP78were increased after treated with hyperglycemia for12h,and then decreased at24h (p<0.05). After pretreated with Exendin-4,the percentage of MS-1cell viability was greatly improved(p<0.05).Furthermore,the present study showed that Exendin-4patently inhibited endoplasmic reticulum stress. Conclusions Hyperglycemia significantly promotes MS-1cells apoptosis in a dose and time-dependent manner,and hyperglycemia induced apoptosis in MS-1cells through endoplasmic reticulum stress pathway.Our results also suggest that Exendin-4pretects against endoplasmic reticulum stress induced apoptosis with ERS and the apoptosis-related signaling. Objective To investigate the effect of palmitinic acid on the apoptosis and proliferation of islet endothelial cell line (MS-1),and the protective effect and possible mechanism of N-acetyl-L-cysteine(NAC) on the endoplasmic reticulum stress pathway of apoptosis.Methods MS-1cells were divided into4groups and were treated respectively with bovine serum albumin(BSA)、pahnitinic acid(1mmol/L)、NAC(10umol/L) and palmitinic acid for12h after NAC pretreated for30min. The apoptosis of each group was detected by FACS, cell proliferation was tested using3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT);GRP78、 CHOP%Xbp-1、caspase-3、caspase-12mRNA expression were examined by reverse transcription and polymerase chain reaction assay (RT-PCR), and the protein expression of GRP78、CHOP were examined by Western blot. The statistical significance was determined by Student’s t-test and one-way ANOVA.Results Compared with BSA, palmitinic acid significantly induced apoptosis while decreased cell viability(p<0.05); the mRNA level of GRP78、CHOP、Xbp-1、 caspase-3、caspase-12and the protein level of GRP78、CHOP were increased (p<0.05). Compared with palmitinic acid,NAC pretreated increased cell viability (p<0.05) and inhibited apoptosis(p<0.05). The mRNA level of GRP78、CHOP、 Xbp-1、caspase-3、caspase-12and the protein level of GRP78、CHOP were decreased by NAC(p<0.05).Conclusions NAC protects MS-1cells from palmitinic acid induced cell apoptosis, which may be mediated by inhibition of endoplasmic reticulum stress.