Role of HSP27 regulating RhoA in bladder smooth muscle remodeling in rats after bladder outlet obstruction

Abstract

Objective To explore the role and underlying mechanism of heat shock protein 27 (HSP27) in bladder smooth muscle remodeling after bladder outlet obstruction (BOO). Methods Rat BOO model was established by urethral orifice hyaluronic acid injection, and the rats from the control group were given the injection of same amount of normal saline. In 4 weeks after model establishment, the bladder wall tissues of BOO and control group were observed by HE staining. The expression of HSP27 and RhoA was detected by Western blotting in both groups. Cultured human bladder smooth muscle cells (BSMCs) were transfected with lentiviral vectors expressing either HSP27 or HSP27-shRNA (shHSP27). Western blotting was used to detect the expression of HSP27, phosphorylated HSP27, RhoA, G-actin and F-actin. Phalloidin fluorescence staining of F-actin was performed in overexpression and control group to observe actin filaments in BSMCs. Results HE staining showed evident bladder smooth muscle hypertrophy in BOO group in 4 weeks after hyaluronic acid injection, indicating the successful establishment of rat BOO model. The expression levels of HSP27 and RhoA were increased significantly compared to those in the control group (P < 0.05). BMSC cell models of HSP27 overexpression and knockdown were successfully established. The Results of Western blotting showed increased expression of HSP27, phosphorylated HSP27 and RhoA in HSP27 overexpression cells (P < 0.05), and decreased expression of these protein in shHSP27 cells (P < 0.05). Also, the F-actin/G-actin ratio was elevated in HSP27 overexpression cells (P < 0.05) and an opposite result was seen in the shHSP27 cells (P < 0.05). Phalloidin fluorescence staining showed there were less actin filaments in shHSP27 cells than the control and HSP27 overexpression cells, and more actin filaments in abnormal arrangement were observed in the overexpression cells than the control cells. Conclusion HSP27 can affect the structure of actin by regulating RhoA, and may play a critical role in bladder smooth muscle remodeling after BOO in rats.

Keywords

• bladder outlet obstruction
• smooth muscle remodeling
• hsp27
• rhoa