Effect of silencing HDAC9 on the proliferation and differentiation of periodontal ligament stem cells

Objective To investigate the effect of silencing histone deacetylase 9 (HDAC9) expression on the proliferation and osteogenic differentiation of periodontal ligament stem cells (PDLSCs). Methods PDLSCs were isolated, cultured and identified in vitro. An siRNA construct specific for HDAC9 was transfected into PDLSCs (siHDAC9 group), and a nontargeting siRNA was used as a control (siNC group). The interference effect was determined by qRT-PCR. The cell cycle progression of PDLSCs was detected using flow cytometry. The proliferation activity of PDLSCs was detected via CCK-8 assay. Western blotting was used to detect the protein expression of proliferating cell nuclear antigen (PCNA). The mRNA expression of runt-related transcription factor 2 (RUNX2) and alkaline phosphatase (ALP) was investigated by qRT-PCR. The protein expression of RUNX2 was detected by western blotting. In addition, the formation of mineralized nodules was assessed by alizarin red staining. Results Compared with that in the siNC group, the mRNA expression of HDAC9 in the siHDAC9 group was lower (P < 0.01). Moreover, compared with those in the siNC group, the proliferation index (P<0.01), proliferation activity (P<0.05) and protein expression of PCNA (P<0.01) in the siHDAC9 group were all increased. Compared with the siNC group, the siHDAC9 group exhibited higher mRNA expression of RUNX2 and ALP (P < 0.05), and the protein expression of RUNX2 showed the same results (P < 0.01). The results of alizarin red staining showed that compared to the siNC group, the siHDAC9 group formed more mineralized nodules. Conclusion Silencing HDAC9 expression can promote the proliferation and osteogenic differentiation of PDLSCs