ETV2 promotes osteogenic differentiation of human dental pulp stem cells through the ERK/MAPK and PI3K-Akt signaling pathways

Background The repair of cranio-maxillofacial bone defects remains a formidable clinical challenge. The Ets variant 2 (ETV2) transcription factor, which belongs to the E26 transformation-specific (ETS) family, has been reported to play a key role in neovascularization. However, the role of ETV2 in the osteogenesis of human dental pulp stem cells (hDPSCs) remains unexplored. Methods Transgenic overexpression of ETV2 was achieved using a lentiviral vector, based on a Dox-inducible system. The effects of Dox-induced overexpression of ETV2 on the osteogenesis of hDPSCs were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR), western blot, immunofluorescence staining, alkaline phosphatase (ALP) staining, and Alizarin Red S (ARS) staining. Additionally, RNA-sequencing (RNA-Seq) analysis was performed to analyze the underlying mechanisms of ETV2-induced osteogenesis. Additionally, the role of ETV2 overexpression in bone formation in vivo was validated by animal studies with a rat calvarial defect model and a nude mice model. Results Our results demonstrated that ETV2 overexpression significantly upregulated the mRNA and protein expression levels of osteogenic markers, markedly enhanced ALP activity, and promoted matrix mineralization of hDPSCs. Moreover, the results of RNA-Seq analysis and western blot showed that the ERK/MAPK and PI3K-Akt signaling pathways were activated upon transgenic overexpression of ETV2. The enhanced osteogenic differentiation of hDPSCs due to ETV2 overexpression was partially reversed by treatment with inhibitors of ERK/MAPK or PI3K-AKT signaling. Furthermore, the results of in vivo studies demonstrated that ETV2 overexpression improved bone healing in a rat calvarial defect model and increased ectopic bone formation in nude mice. Conclusions Collectively, our results indicated that ETV2 overexpression exerted positive effects on the osteogenesis of hDPSCs, at least partially via the ERK/MAPK and PI3K/AKT signaling pathways.

Automated summary

This study demonstrated that overexpression of ETV2 significantly enhanced osteogenic markers expression, ALP activity, and matrix mineralization of hDPSCs. The mechanisms involved ERK/MAPK and PI3K-Akt signaling pathways, which were partially reversed by inhibitors of these pathways. In vivo studies also showed improved bone healing and ectopic bone formation due to ETV2 overexpression in animal models.