FK506 enhances bone morphogenetic protein 9-induced cementoblast differentiation in human cementoblast-lineage cells.

Bone morphogenetic protein 9 (BMP9) has strong osteogenic potential and has emerged as a promising therapeutic target for periodontal wound healing and regeneration. However, although BMP9 induces osteoblastic differentiation, its effects on cementoblasts and potential synergistic interactions with FK506, an immunosuppressive drug, are unknown. This study investigated the combined effects of BMP9 and FK506 treatment on cementoblast differentiation using a human cementoblast-like cell line, HCEM. BMP9 significantly upregulated alkaline phosphatase activity, mineralization, and the expression of mineralized tissue-related genes, including IBSP and SPP1, in HCEM cells, with FK506 co-treatment further enhancing these effects. FK506 also augmented BMP9-induced phosphorylation of SMAD1/5/8, ERK1/2, and p38, as shown by western blotting. Moreover, silencing of FKBP1A, which encodes FK506-binding protein 12 (FKBP12)-a key regulator of BMP signaling-enhanced BMP9 responsiveness, confirming its regulatory role. Neither BMP9 nor FK506 affected cell proliferation. In conclusion, BMP9 induces cementoblast differentiation via SMAD1/5/8, ERK1/2, and p38 pathways in HCEM cells, which are further enhanced through the regulation of FKBP12 by FK506. The combination of BMP9 and FK506 may offer a promising strategy for periodontal wound healing and regeneration, warranting further preclinical and clinical investigations.