[Over-expression of thioredoxin-interacting protein promotes apoptosis of MIN6 cells via activating p38MAPK pathway].

Objective To investigate the effect of thioredoxin interacting protein (TXNIP) over-expression on the apoptosis of MIN6 β-cells and the mechanism involved. Methods Lentivirus carrying TXNIP gene was used to infect MIN6 β-cells in logarithmic growth phase, and the infection efficiency was evaluated by fluorescence microscope and Western blotting. Then MIN6 β-cells were divided into three groups: control group, empty lentivirus vector (LV-GFP) group and TXNIP over-expression (LV-GFP-TXNIP) group. CCK-8 assay was used to detect cell proliferation. AnnexinV-FITC/PI double staining was utilized to measure the apoptosis of MIN6 cells. Western blotting was applied to detect the expressions of TXNIP protein, TRX, Bax, Bcl2, cleaved caspase-3 (c-caspase-3), p38 mitogen-activated protein kinase (p38MAPK), phospho-p38MAPK (p-p38MAPK) proteins in the MIN6 β-cells before and after treated with p38MAPK inhibitor SP169316. Results At 72 hours after the infection, the infection rate reached (87.10±2.30)% and (92.21±0.54)% in LV-GFP group and LV-GFP-TXNIP group, respectively, suggesting that lentivirus-mediated TXNIP over-expression was desirable. Compared with control group and LV-GFP group, the cell viability markedly decreased, and cell apoptosis, Bax/Bcl2 ratio, expression of c-caspased-3 and p38MAPK phosphorylation significantly increased in LV-GFP-TXNIP group. However, both the Bax/Bcl2 ratio and c-caspase-3 protein expression in LV-GFP-TXNIP group were obviously reduced after treated with p38MAPK inhibitor. Conclusion TXNIP over-expression might promote the apoptosis of MIN6 cells via activating the p38 MAPK pathway.