Effect of c-Src kinase on the expression of occludin during the inflammation process mediated by lipopolysaccharide

Objective To investigate the effect of c-Src kinase on the expression of the tight junction protein occludin during lipopolysaccharides (LPS) treatment on mouse lung epithelial-12(MLE-12) cells. Methods The cultured MLE-12 cells were randomly divided into 3 groups: control group (group C), LPS group (group L), LPS+c-Src kinase inhibitor (PP2) group (group L+P). In group L, MLE-12 cells were treated with LPS (10 mg/L) for 1, 3, 6 h, respectively. In group L+P, MLE-12 cells were treated with c-Src kinase inhibitor PP2 (100 μmol/L) for 30 min then LPS (10 mg/L) for 6h. Non-treatment was given in group C. The expression of occludin was determined in MLE-12 cells using Western blot and immunofluorescence. Results In our study, we found that compared with group C, the expression of occludin of group L was significantly down-regulated at 6 h (P<0.05) and c-Src was up-regulated (P<0.05). The expression of occludin was significantly up-regulated in group L+P (P<0.05) at 6 h compared with group L. Immunofluorescence showed that occludin which distributed in cytomembrane could be affected by LPS, and PP2 could alleviate the effect of LPS. And the level of occludin was increased after treated with PP2 in group L+P. Conclusions LPS leads to decreasing of the expression of occludin in MLE-12 cells, with c-Src involved in the process. Key words: c-Src kinase; Lipopolysaccharide; Tight Junctions; Occludin