IRF1 regulates apoptosis and osteogenic differentiation of bone marrow mesenchymal stem cells and ameliorates osteoporosis by activating the PI3K/AKT signaling pathway

BACKGROUND: Bone marrow mesenchymal stem cells (BMSCs) are a critical cell type for stem cell-based bone regenerative therapy. Promoting osteogenic differentiation of BMSCs is important for the promotion of bone formation. Interferon regulatory factor 1 (IRF1) was discovered as an essential factor in immune responses and the differentiation of several cell lines. Nevertheless, the potential of IRF1 as a therapeutic target for the modulation of BMSCs in the context of bone regeneration strategies remains unexplored. Here, we investigated the role of IRF1 in BMSC fate determination and demonstrated IRF1 as a promising target for osteoporosis. METHODS: Irf1-overexpressing and Irf1-knockdown murine BMSCs (mBMSCs) were established by plasmid and lentivirus transfection, and the expression efficiency was verified. The role of IRF1 in regulating the proliferation, migration, apoptosis, and osteogenic differentiation of mBMSCs in vitro was investigated using gain- and loss-of-function experiments. In addition, Irf1-overexpressing mBMSCs were implanted subcutaneously with scaffold material into the backs of nude mice to evaluate the ectopic osteogenesis capability in vivo. Irf1-overexpressing mBMSCs were injected into the tail vein of ovariectomized and aging-related osteoporosis mouse models to evaluate their therapeutic effects. In addition, the underlying mechanisms were explored by RNA sequencing and validated through real-time reverse transcription-polymerase chain reaction (RT-PCR) and western blotting (WB) analysis. RESULTS: Overexpression of Irf1 promoted the proliferation, migration, and osteogenic differentiation of mBMSCs, and suppressed apoptosis in vitro, while Irf1 knockdown had the opposite effects. Irf1-overexpressing mBMSCs also promoted ectopic bone formation and alleviated osteoporosis compared to controls in vivo. IRF1 may regulate the fate of mBMSCs through activation of the PI3K/AKT signaling pathway. CONCLUSION: This study suggested that overexpression of Irf1 promotes osteogenic differentiation of BMSCs and has a therapeutic effect on osteoporosis. IRF1 could play dual roles as a biomarker for bone formation and a potential target for osteoporosis treatment.