The Effect And Mechanism Of DAXX On Vascular Smooth Muscle Cell Proliferation

Background: PTEN is an important protein in VSMC(vascular smooth muscle cell) proliferation, which mediates the PI3K/AKT signaling pathway. The level of PTEN is regulated by DAXX that promotes nuclear PTEN outflow, but the role of DAXX in VSMC proliferation remains to be further validated.Objective: Aimed to evaluate the critical role of DAXX in inhibiting VSMC proliferation.Methods: VSMC were stably transfected with control vector pcDNA3.1(+)-DAXX, siRNA or siRNA-DAXX, respectively. Western blot and RT-PCR were used to assay the transfection efficiency; MTT was used to detect the cell viability; FCM was used to analyze the VSMC cycle. The protein expression of PTEN, AKT and P-AKT was respectively detected by Western blot, and the expression of PTEN mRNA was assayed by RT-PCR.Results: Western blot and RT-PCR analyses showed that expression of DAXX was dramatically increased compared to the control group, indicating that stable transfection was successfully established. MTT results showed that DAXX inhibited VSMC growth, whereas the siRNA-DAXX promoted cell growth. Compared with the normal control group, flow cytometry found that a larger proportion of cells transfected with the DAXX decreased in the S phase, whereas, an opposite result was observed in cells transfected with the si RNA-DAXX; both RT-PCR and Western blot assays showed that DAXX could increase the expression of PTEN, whereas siRNA-DAXX could inhibit the PTEN expression. Western blot assays also showed that when cells were transfected with pcDNA3.1(+)-DAXX, the expression of P-AKT was significantly decreased; while in the cells transfected with siRNA-DAXX, the expression of P-AKT was increased without any big difference on the level of AKT in both condition.Conclusion: DAXX can inhibit vascular smooth muscle cell proliferation, which is stimulated by 10%FBS,and this maybe related to PTEN/AKT signaling pathway.