Department of Periodontology, University of Florida, Gainesville, FL 32610, USA.
Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA.
Bone. 2023 May;170:116709. doi: 10.1016/j.bone.2023.116709. Epub 2023 Mar 1.
FBXO11 is the substrate-recognition component of a ubiquitin ligase complex called SKP1-cullin-F-boxes. The role of FBXO11 in bone development is unexplored. In this study, we reported a novel mechanism of how bone development is regulated by FBXO11. FBXO11 gene knockdown by lentiviral transduction in mouse pre-osteoblast MC3T3-E1 cells leads to reduced osteogenic differentiation, while overexpressing FBXO11 accelerates their osteogenic differentiation in vitro. Furthermore, we generated two osteoblastic-specific FBXO11 conditional knockout mouse models, Col1a1-ERT2-FBXO11KO and Bglap2-FBXO11KO mice. In both conditional FBXO11KO mouse models, we found FBXO11 deficiency inhibits normal bone growth, in which the osteogenic activity in FBXO11cKO mice is reduced, while osteoclastic activity is not significantly changed. Mechanistically, we found FBXO11 deficiency leads to Snail1 protein accumulation in osteoblasts, leading to suppression of osteogenic activity and inhibition of bone matrix mineralization. FBXO11 knockdown in MC3T3-E1 cells reduced Snail1 protein ubiquitination and increased Snail1 protein accumulation in the cells, which eventually inhibited osteogenic differentiation. In conclusion, FBXO11 deficiency in osteoblasts inhibits bone formation through Snail1 accumulation, inhibiting osteogenic activity and bone mineralization.
FBXO11 是一种称为 SKP1-cullin-F-boxes 的泛素连接酶复合物的底物识别组件。FBXO11 在骨骼发育中的作用尚未被探索。在这项研究中，我们报道了 FBXO11 调节骨骼发育的新机制。通过慢病毒转导在小鼠前成骨细胞 MC3T3-E1 细胞中敲低 FBXO11 基因导致成骨分化减少，而过表达 FBXO11 则加速其体外成骨分化。此外，我们生成了两种成骨细胞特异性 FBXO11 条件性敲除小鼠模型，Col1a1-ERT2-FBXO11KO 和 Bglap2-FBXO11KO 小鼠。在这两种条件性 FBXO11KO 小鼠模型中，我们发现 FBXO11 缺失抑制正常骨生长，其中 FBXO11cKO 小鼠的成骨活性降低，而破骨活性没有明显变化。在机制上，我们发现 FBXO11 缺失导致成骨细胞中 Snail1 蛋白积累，从而抑制成骨活性和骨基质矿化。在 MC3T3-E1 细胞中敲低 FBXO11 减少了 Snail1 蛋白的泛素化，并增加了细胞中 Snail1 蛋白的积累，最终抑制了成骨分化。总之，成骨细胞中 FBXO11 的缺失通过 Snail1 积累抑制骨形成，抑制成骨活性和骨矿化。
