Cdc42-dependent endocytosis pathway in the regulation of Na+ /H+ exchanger 3 (NHE3) expression on rotavirus-infected Caco-2 cells

Objective To observe the effects and regulatory mechanism of rotavirus infection on the expression and bioactivity of Na+ /H+ exchanger 3 (NHE3) on Caco-2 cells. Methods A cell model of Caco-2 cells expressing NHE3 was constructed. Four groups were set up, which were control (CTL) group, rotavirus(RV) infection group, Cdc42 inhibitor (Pirl-1) group and Pirl-1+ RV group. Bioactivity and expression of NHE3 on the surface of Caco-2 cells were determined by BCECF-AM and biotinylation method, respectively. Expression of Cdc42 protein was measured by Western blot. Co-immunoprecipitation was performed to detect the interaction between NHE3 and Cdc42. Results Compared with the CTL group, RV infection significantly inhibited the bioactivity and expression of NHE3 on Caco-2 cells. These inhibitory effects were antagonized by Pirl-1. Moreover, RV infection enhanced the expression of Cdc42 protein and promoted the interaction between NHE3 and Cdc42, which were also antagonized by Pirl-1. Conclusion RV infection might regulate the expression and bioactivity of NHE3 through Cdc42-dependent endocytosis pathway. Key words: Rotavirus; Na+ /H+ exchanger 3; Cdc42-dependent endocytosis pathway