Abstract: Abstract: Objective To investigate the role of signal transducers and activators of transcription 1 (STAT1) on osteoblast differentiation of human periodontal ligament cells and the underlying mechanism. Methods Primary human periodontal ligament cells were isolated and cultured by enzyme-digestion method. Lipopolysaccharide (LPS) was used to stimulate human periodontal ligament cells. The osteoblast differentiation of human periodontal ligament cells was induced by osteogenetic differentiation medium. STAT1 overexpression or gene silencing was achieved by transfection of STAT1 overexpression vectors or small interfering RNA (siRNA), respectively. Osteoblast differentiation was detected by alkaline phosphatase (ALP) assay kit and Alizarin red S staining. The mRNA expression levels of STAT1, collagen type Iα1 (ColA1) and osteopontin (OPN) were detected by real-time quantitative PCR analysis. The protein expression levels of STAT1 and runt-related transcription factor 2 (Runx2) were detected by Western blot analysis. Results LPS stimulation significantly upregulated the expression of STAT1. Overexpression of STAT1 significantly inhibited the ALP activity, bone matrix mineralization, nuclear translocation of Runx2 and the expression of ColA1and OPN. In contrast, STAT1 gene silencing markedly increased the ALP activity, bone matrix mineralization, nuclear translocation of Runx2 and the expression of ColA1and OPN. Conclusions STAT1 gene silencing promotes osteoblast differentiation of human periodontal ligament cells through increasing the nuclear translocation of Runx2.

Key words: signal transducers and activators of transcription 1, human periodontal ligament cells, osteoblast differentiation