Semaphorin 4D Enhances Angiogenic Potential and Suppresses Osteo-/Odontogenic Differentiation of Human Dental Pulp Stem Cells

摘要

Introduction: To investigate the roles of semaphorin 4D (Sema4D)/plexin-B1 signaling on the angiogenic potential and osteo-/odontogenic differentiation of human dental pulp stem cells (DPSCs) and to uncover the corresponding molecular mechanisms. Methods: DPSCs were treated with Sema4D (10 mu g/mL) for different time durations. Osteo-/odontogenic differentiation was assessed by quantifying alkaline phosphatase activity, mineralized nodule formation, and osteo-/odontogenic gene (ALP, Col1A1, esti, RUNX2, and DSPP) and protein (Col1A1 and DSPP) expression. Involvement of the Sema4D/plexin-B1 signaling pathway was analyzed by Western blot analysis. Additionally, angiogenic gene and protein expression was assessed by reverse transcription polymerase chain reaction and enzyme linked immunosorbent assay. In vitro endothelial tube formation assay on Matrigel (BD Biosciences, San Jose, CA) was performed to evaluate the angiogenic inductive potential of the Sema4D-treated DPSCs conditioned medium. Results were analyzed using 1-way analysis of variance and the Student t test. Results: Sema4D significantly inhibited ALP activity and mineralized nodule formation of DPSCs. Furthermore, Sema4Dtreated DPSCS displayed marked down -regulation in the expression of osteo-/odontogenic genes (ALP; Col1A1, BSP, RUNX2, and DSPP) as well. as proteins (Col1A1 and DSPP). Elevated levels of plexin-B1 and downstream RhoA protein expression together with phosphorylated plexin-B1 confirmed the involvement of Sema4D/plexin-B1 signaling. Protein expression of ErbB2 was up-regulated, and Met was slightly down regulated. Furthermore, Sema4D-treated DPSCs exhibited enhanced expression of vascular endothelial growth factor at both the messenger RNA and protein level. Accordingly, the conditioned medium of Sema4D-treated DPSCs promoted the formation of vessel-like structures as shown by the Matrigel assay. Conclusions: Sema4D markedly enhances the angiogenic potential but suppresses osteo-/odontogenic differentiation of DPSCs. Sema4D/plexin-B signaling was activated via the RhoA-mediated pathway.