PML Regulated HIF1AN Ubiquitination and Activated PI3K/AKT Pathway to Promote Bone Marrow Mesenchymal Stem Cells Osteogenic Differentiation.

Osteoporosis (OP) is a metabolic disease caused by osteogenesis and bone resorption disorders. Promyelocytic leukemia protein (PML) was a vital regulator of cellular functions. However, the function of PML in OP remains unknown. Our research aimed to illustrate the molecular mechanism of PML in bone marrow mesenchymal stem cells (BMSCs) osteogenic differentiation. The BMSCs were identified by using flow cytometry analysis. The osteoblast differentiation ability of BMSCs was assessed through using alkaline phosphatase and Alizarin red S stainings. The relationship between hypoxia-inducible factor-1α (HIF1α) and superoxide dismutase 3 (SOD3) were confirmed by using chromatin immunoprecipitation and dual-luciferase reporter assays. The binding association between PML and hypoxia-inducible factor 1α inhibitor (HIF1AN) proteins was verified by using co-immunoprecipitation assay and immunofluorescence staining. Western blot was used for protein detection. PML was up-regulated in osteogenic differentiation of BMSCs. Functionally, PML negatively regulated HIF1AN expression by enhancing HIF1AN ubiquitination degradation. PML knockdown or HIF1AN up-regulation suppressed the osteogenic differentiation of BMSCs. Furthermore, HIF1α directly bound to the SOD3 promoter region. PML or SOD3 overexpression remarkably promoted the BMSCs osteoblast differentiation under osteogenic medium, which was reversed by LY294002. PML acts as a significant regulator in the BMSCs osteogenic differentiation by regulating the HIF1AN/HIF1α/SOD3 axis and phosphatidylinositol 3 kinase/protein kinase B pathway.