Zhou Liming, Ogata Yorimasa
Department of Periodontology, Nihon University School of Dentistry at Matsudo, Matsudo, Japan.
J Oral Sci. 2013 Mar;55(1):63-70. doi: 10.2334/josnusd.55.63.
Fibroblast growth factor 2 (FGF2), a member of the FGF family, positively regulates bone formation and osteoblast differentiation. Bone sialoprotein (BSP) is highly expressed during early bone formation and may play a role in primary mineralization of bone. In the present study, FGF2 (10 ng/mL) was found to increase the levels of Runx2 and BSP mRNA at 3 and 12 h in human osteoblast-like Saos2 cells. Transient transfection assays were performed using chimeric constructs of the human BSP gene promoter ligated with a luciferase reporter gene. FGF2 (10 ng/mL, 12 h) induced the luciferase activities of the -84LUC and -927LUC constructs in Saos2 cells. The results of gel shift assays showed that FGF2 (10 ng/mL) increased the binding of nuclear protein to the FGF2 response element (FRE) and the activator protein 1 (AP1) binding site. Antibodies against Dlx5, Msx2, Runx2 and Smad1 blocked FRE-protein complex formation, and antibodies against CREB1, c-Jun and Fra2 interrupted AP1-protein complex formation. These results indicate that FGF2 increases BSP transcription by targeting the FRE and AP1 elements in the proximal promoter of the human BSP gene. Moreover, the transcription factors Dlx5, Msx2, Runx2, Smad1, CREB1, c-Jun and Fra2 could be key regulators of the effects of FGF2 on human BSP transcription.
成纤维细胞生长因子2（FGF2）是FGF家族的成员之一，对骨形成和成骨细胞分化起正向调节作用。骨唾液酸蛋白（BSP）在早期骨形成过程中高表达，可能在骨的初级矿化中发挥作用。在本研究中，发现FGF2（10 ng/mL）可在3小时和12小时时增加人成骨样Saos2细胞中Runx2和BSP mRNA的水平。使用与人BSP基因启动子连接的荧光素酶报告基因的嵌合构建体进行瞬时转染实验。FGF2（10 ng/mL，12小时）诱导了Saos2细胞中-84LUC和-927LUC构建体的荧光素酶活性。凝胶迁移实验结果表明，FGF2（10 ng/mL）增加了核蛋白与FGF2反应元件（FRE）和激活蛋白1（AP1）结合位点的结合。针对Dlx5、Msx2、Runx2和Smad1的抗体可阻断FRE-蛋白复合物的形成，针对CREB1、c-Jun和Fra2的抗体可阻断AP1-蛋白复合物的形成。这些结果表明，FGF2通过靶向人BSP基因近端启动子中的FRE和AP1元件来增加BSP转录。此外，转录因子Dlx5、Msx2、Runx2、Smad1、CREB1、c-Jun和Fra2可能是FGF2对人BSP转录作用的关键调节因子。
