Hu Sujie, Chen Sisi, Zeng Haozu, Ruan Xinyi, Lin Xinyi, Vlashi Rexhina, Zhou Chenhe, Wang Haidong, Chen Guiqian
Department of Biopharmacy, College of Life Science and Medicine, Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
Department of Orthopedic Surgery, the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou City, Zhejiang Province, PR China.
Dev Biol. 2023 Sep;501:81-91. doi: 10.1016/j.ydbio.2023.06.015. Epub 2023 Jun 22.
The skull is a fundamental bone that protects the development of brain and consists of several bony elements, such as the frontal and parietal bones. Frontal bone exhibited superior in osteogenic potential and regeneration of cranial defects compared to parietal bone. However, how this regional difference is regulated remains largely unknown. In this study, we identified an Ap-2β transcriptional factor with a higher expression in frontal bone, but its molecular function in osteoblasts needs to be elucidated. We found that Ap-2β knockdown in preosteoblasts leads to reduced proliferation, increased cell death and impaired differentiation. Through RNA-seq analysis, we found that Ap-2β influences multiple signaling pathways including the Wnt pathway, and overexpression of Ap-2β showed increased nuclear β-catenin and its target genes expressions in osteoblasts. Pharmacological activation of Wnt/β-catenin signaling using LiCl treatment cannot rescue the reduced luciferase activities of the β-catenin/TCF/LEF reporter in Ap-2β knockdown preosteoblasts. Besides, transient expression of Ap-2β via the lentivirus system could sufficiently rescue the inferior osteogenic potential in parietal osteoblasts, while Ap-2β knockdown in frontal osteoblasts resulted in reduced osteoblast activity, reduced active β-catenin and target genes expressions. Taken together, our data demonstrated that Ap-2β modulates osteoblast proliferation and differentiation through the regulation of Wnt/β-catenin signaling pathway and plays an important role in regulating regional osteogenic potential in frontal and parietal bone.
颅骨是保护大脑发育的基础骨骼，由多个骨成分组成，如额骨和顶骨。与顶骨相比，额骨在成骨潜力和颅骨缺损修复方面表现更优。然而，这种区域差异是如何被调控的，目前仍 largely未知。在本研究中，我们鉴定出一种在额骨中高表达的Ap-2β转录因子，但其在成骨细胞中的分子功能尚待阐明。我们发现，前成骨细胞中Ap-2β基因敲低会导致增殖减少、细胞死亡增加和分化受损。通过RNA测序分析，我们发现Ap-2β影响包括Wnt信号通路在内的多个信号通路，且在成骨细胞中过表达Ap-2β会使核内β-连环蛋白及其靶基因表达增加。用氯化锂处理对Wnt/β-连环蛋白信号通路进行药理学激活，无法挽救Ap-2β基因敲低的前成骨细胞中β-连环蛋白/TCF/LEF报告基因的荧光素酶活性降低的情况。此外，通过慢病毒系统瞬时表达Ap-2β能够充分挽救顶骨成骨细胞较差的成骨潜力，而额骨成骨细胞中Ap-2β基因敲低则导致成骨细胞活性降低、活性β-连环蛋白及其靶基因表达减少。综上所述，我们的数据表明，Ap-2β通过调控Wnt/β-连环蛋白信号通路调节成骨细胞的增殖和分化，并在调节额骨和顶骨的区域成骨潜力中发挥重要作用。
