Effect And Mechanism Of Thyroid Hormone On Insulin Resistance Of Islet ? Cells

Objective1.To investigate the effect of free triiodothyronine?FT3?on the insulin resistance of mouse pancreatic islet?-cell?MIN6?cell line by detected the expression of insulin signaling pathway protein in mouse islet?cells.2.To explore the role of endoplasmic reticulum stress induced by high FT3 in insulin resistance of MIN6 cells.Method1.The mouse islet??MIN6?cell was cultured and seeded in the six-hole plate in vitro.When cultured the cells to a degree of fusion of 80%,divided the cells into experimental group?high FT3?and control group?normal FT3?,endoplasmic reticulum stress inhibitor group?high FT3+4-PBA?,insulin resistance inhibitor group?high FT3+sodium vanadate?,experimental group with 20 pg/ml FT3,control group with 5 pg/ml FT3,Inhibitor group was 20pg/ml FT3+1mmol/L4-PBA and 20pg/ml FT3+5umol/L sodium vanadate.After intervention of MIN6 cells for 48 hours,used western blot to detect IRS-1^Ser307?Phosphorylation site of Ser307?,Akt and other insulin signaling pathway proteins and endoplasmic reticulum stress-related proteins such as PERK,IRE1,ATF6,and GRP78,and expression levels of endoplasmic reticulum-specific apoptotic proteins such as CHOP and caspase12.Then compared the expression differences among the control group,the experimental group and inhibitor group;2.Used Enzyme linked immunosorbent assay?Elisa?to detect and compare the insulin concentration in the supernatants of each group.Result1.The expression of IRS-1^Ser307er307 in the high FT3 group was significantly higher than that in the normal FT3 group,and the expression level of Akt was significantly lower than that of the normal FT3 group.Pairing t test showed p<0.05,the difference was statistically significant.In the supernatant insulin assay,the insulin concentration in the supernatant of the high FT3 group was significantly lower than that in the normal FT3group,and the paired t-test yielded P<0.05,with a statistically significant difference.After the insulin resistance inhibitor sodium vanadate was added,the expression of IRS-1^Ser307er307 in the high FT3+sodium vanadate group was significantly lower than that in the high FT3 group,and the expression level of Akt was significantly higher than that in the high FT3 group,and the paired t-test had P<0.05,which has statistical significance.In the supernatant insulin assay,the insulin concentration in the supernatant of the high FT3+sodium vanadate group was significantly higher than that in the high FT3 group,and the paired t-test had P<0.05,which was statistically significant.2.The expressions of endoplasmic reticulum stress-related proteins such as PERK,IRE1,ATF6,and GRP78 in the high FT3 group were significantly higher than those in the normal FT3 group,and the paired t-test had P<0.05,the difference was statistically significant.After added endoplasmic reticulum stress inhibitor 4-PBA,the expression of endoplasmic reticulum stress-related proteins such as PERK,IRE1,ATF6,and GRP78in the high FT3+4-PBA group was significantly lower than that in the high FT3 group,and the pairing t test showed p<0.05,the difference was statistically significant.After the endoplasmic reticulum stress inhibitor 4-PBA was added,the expression of IRS-1^Ser307er307 in the high FT3+4-PBA group was significantly lower than that in the high FT3 group,and the expression level of Akt was significantly higher than that in the high FT3 group.The paired t-test showed P<0.05,the difference was statistically significant.After the endoplasmic reticulum stress inhibitor was added,the insulin concentration in the supernatant of the high FT3+4-PBA group was significantly higher than that in the high FT3 group,and the paired t-test had P<0.05,with a statistically significant difference.3.The expression of apoptosis-related proteins such as CHOP and caspase12 in the high FT3 group was significantly higher than that in the normal FT3 group,and the paired t-test had P<0.05.The difference was statistically significant.After endoplasmic reticulum stress inhibitors were added,the expression of apoptosis-related proteins such as CHOP and caspase12 in the high FT3+4-PBA group was significantly lower than that in the high FT3 group,and the paired t-test had P<0.05,which was statistically significant.Conclusion1.High FT3 induces up-regulation of insulin signaling protein IRS-1^Ser307expression in MIN6 cells,Akt expression is downregulated,and inhibit the secretion of insulin in MIN6 cells,that high FT3 may cause islet?cell insulin resistance.2.High FT3 can increase the expression of endoplasmic reticulum related proteins such as PERK,IRE1,ATF6 and GRP78 in MIN6 cells.After endoplasmic reticulum stress inhibitors are added,endoplasmic reticulum associated proteins such as PERK,IRE1,ATF6 and GRP78 are increased.The expression of insulin signal pathway protein(IRS-1^Ser307)is down-regulated and the insulin secretion is up-regulated.That is,high FT3 may induce endoplasmic reticulum stress and induce insulin resistance in islet cells through endoplasmic reticulum stress pathway.3.High FT3 can induce up-regulation of apoptosis-related proteins such as CHOP,Caspase12 in MIN6 cells,and promote apoptosis in MIN6 cells by up-regulation of endoplasmic reticulum stress-specific apoptotic protein CHOP,Caspase12,and participate in insulin resistance of islet?cells.