ITGA1 promotes osteogenic differentiation of human periodontal ligament stem cells via FAK-mediated PI3K–Akt activation

Background Human periodontal ligament stem cells (hPDLSCs) possess promising potential for bone regeneration; however, the regulation of their osteogenic differentiation remains incompletely understood. Integrin α1 (ITGA1) has been implicated in multiple cellular processes, but its role in hPDLSC osteogenesis requires further investigation. Methods ITGA1 was overexpressed in hPDLSCs using an adenoviral vector, and osteogenic differentiation was evaluated by alkaline phosphatase (ALP) staining and gene expression analysis. Loss-of-function experiments were performed using ITGA1 knockdown. Data-independent acquisition (DIA) proteomics, protein–protein interaction (PPI) analysis, immunoprecipitation–mass spectrometry (IP–MS), and co-immunoprecipitation (Co-IP) were employed to explore the underlying mechanisms. Functional validation was performed using gene silencing and pharmacological inhibition, and in vivo efficacy was assessed in a rat mandibular bone defect model. Results Overexpression of ITGA1 enhanced osteogenic differentiation, while its knockdown produced the opposite effect. Proteomic analysis identified multiple differentially expressed proteins, including integrin family members, suggesting potential functional specificity. ITGA5 knockdown did not impair ITGA1-mediated osteogenesis. PPI and Co-IP analyses supported an interaction between ITGA1 and focal adhesion kinase (FAK). Inhibition of FAK or PI3K–Akt signalling reduced the pro-osteogenic effects of ITGA1. In vivo, transplantation of ITGA1-overexpressing hPDLSCs promoted bone regeneration in rat mandibular defects. Conclusions Activation of the FAK/PI3K–Akt signalling pathway contributes to the promoting effect of ITGA1 on osteogenic differentiation of hPDLSCs. These findings provide insight into integrin-mediated regulation of hPDLSC osteogenesis and may inform future strategies for bone regeneration.