ANKRD1 activates the Wnt signaling pathway by modulating CAV3 expression and thus promotes BMSC osteogenic differentiation and bone formation in ovariectomized mice.

Bone marrow-derived mesenchymal stem cells (BMSCs) are considered promising materials for treating bone diseases such as osteoporosis (OP). This research explored the functions and molecular mechanism of ankyrin repeat domain 1 (ANKRD1) in BMSC osteogenesis. An OP model in mice was established by bilateral ovariectomy. Manipulation of ANKRD1 expression in BMSCs or femurs was achieved by lentivirus infection. Increased ANKRD1 expression was observed in BMSCs during osteogenic induction. Silencing of ANKRD1 impaired the osteogenesis of BMSCs, as shown by the decreased alkaline phosphatase (ALP) activity, osteogenic gene (Runx2, Col1a1, Bglap, and Spp1) expression, and mineralized formation. ANKRD1-mediated promotion of osteogenesis was also reproduced in mouse MC3T3-E1 preosteoblastic cells. Activation of Wnt/β-catenin signaling, a well-known osteogenic stimulus, was also impaired in ANKRD1-silenced BMSCs. Overexpression of ANKRD1 resulted in the opposite effects on osteogenesis and Wnt/β-catenin signaling. Mechanistic studies revealed that ANKRD1 modulated caveolin-3 (CAV3) expression by reducing CAV3 ubiquitination, and the knockdown of CAV3 impaired the functions of ANKRD1. Additionally, a very low level of ANKRD1 was observed in the BMSCs from OP mice. Rescue of ANKRD1 significantly restored osteogenic differentiation and Wnt signaling activation in BMSCs from ovariectomized mice. The results of micro-CT, H&E staining, and IHC staining showed that ANKRD1 also promoted bone formation and Wnt activation and ameliorated pathological alterations in the femurs of OP mice. Collectively, this study demonstrated that ANKRD1 plays an important role in regulating the osteogenic differentiation of BMSCs and is a promising target for the treatment of OP and other bone diseases.