Wang Nan, Liu Wei, Tan Tao, Dong Chao-Qun, Lin Duan-Yang, Zhao Jun, Yu Chang, Luo Xiao-Ji
Department of Orthopedics, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China.
Department of Orthopedics, The Affiliated Children's Hospital of Chongqing Medical University, Chongqing 400014, P.R. China.
Oncotarget. 2017 Nov 30;8(65):109661-109674. doi: 10.18632/oncotarget.22763. eCollection 2017 Dec 12.
Although interaction between BMP and Notch signaling has been demonstrated to be crucial for osteogenic differentiation of mesenchymal stem cells (MSCs), the precise molecular mechanism remains unknown. Here, we show that Notch intracellular domain (NICD) overexpression inhibits BMP9-induced C3H10T1/2 cell osteogenesis and . Our results show that activated Notch signaling results in down-regulation of Runx2 and early osteogenesis differentiation factors, without affecting p-Smad1/5/8 expression, and that blocking Notch signaling with DAPT (N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester) significantly increases p-Smad1/5/8 expression. Interestingly, Notch signaling also regulates the cell cycle by increasing PCNA (proliferation cell nuclear antigen) and CyclinD1 expression. Furthermore, similar results were obtained by ectopic bone formation and histological analyses, indicating that Notch signaling activation significantly inhibits BMP9-induced MSC osteogenic, cartilage and adipogenic differentiation. Moreover, we are the first to show that Notch regulates by suppressing JunB synthesis and that the negative effect of Notch is partially reversed by treatment with the JunB activator TPA (12-O-tetradeca-noylphorbol-13-acetate). Our findings demonstrate that Notch signaling significantly enhances cell proliferation but inhibits MSC osteogenic differentiation induced by BMP9 via JunB protein suppression rather than by BMP/Smad signaling regulation.
尽管已证明骨形态发生蛋白（BMP）与Notch信号之间的相互作用对于间充质干细胞（MSC）的成骨分化至关重要，但其精确的分子机制仍不清楚。在此，我们表明Notch细胞内结构域（NICD）过表达抑制BMP9诱导的C3H10T1/2细胞成骨 。我们的结果表明，激活的Notch信号导致Runx2和早期成骨分化因子的下调，而不影响p-Smad1/5/8的表达，并且用DAPT（N-[N-(3,5-二氟苯乙酰基)-L-丙氨酰基]-S-苯甘氨酸叔丁酯）阻断Notch信号会显著增加p-Smad1/5/8的表达。有趣的是，Notch信号还通过增加增殖细胞核抗原（PCNA）和细胞周期蛋白D1的表达来调节细胞周期。此外，通过异位骨形成和组织学分析也获得了类似的结果，表明Notch信号激活显著抑制BMP9诱导的MSC成骨、软骨和脂肪生成分化。此外，我们首次表明Notch通过抑制JunB合成来进行调节，并且Notch的负面影响可通过用JunB激活剂佛波酯（TPA，12-O-十四烷酰佛波醇-13-乙酸酯）处理而部分逆转。我们的研究结果表明，Notch信号显著增强细胞增殖，但通过抑制JunB蛋白而非通过调节BMP/Smad信号来抑制BMP9诱导的MSC成骨分化。
