AP1 binding site is another target of FGF2 regulation of bone sialoprotein gene transcription

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• 作者：Hideki Takai ; Shouta Araki ; Masaru Mezawa ; Dong-Soon Kim ; Xinyue Li ; Li Yang ; Zhengyang Li ; Zhitao Wang ; Youhei Nakayama ; Yorimasa Ogata
• 关键词：Activator protein 1 ; Bone sialoprotein ; Fibroblast growth factor 2 ; FGF2 response element ; Glucocorticoid response element ; Transcription
• 刊名：Gene
• 出版年：2008
• 出版时间：29 February 2008
• 年：2008
• 卷：410
• 期：1
• 页码：97-104
• 全文大小：780 K

文摘

Bone sialoprotein (BSP) is an early marker of osteoblast differentiation. We previously reported that fibroblast growth factor 2 (FGF2) regulates BSP gene transcription via FGF2 response element (FRE) in the proximal promoter of rat BSP gene. We here report that activator protein 1 (AP1) binding site overlapping with glucocorticoid response element (GRE) AP1/GRE in the rat BSP gene promoter is another target of FGF2. Using the osteoblastic cell line ROS17/2.8, we determined that BSP mRNA levels increased by 10 ng/ml FGF2 at 6 and 12 h. Runx2 protein levels increased by FGF2 (10 ng/ml) at 3 h. Treatment of ROS17/2.8 cells with FGF2 (10 ng/ml, 12 h) increased luciferase activities of constructs including − 116 to + 60 and − 938 to + 60 of the rat BSP gene promoter. Effects of FGF2 abrogated in constructs included 2 bp mutations in the FRE and AP1/GRE elements. Luciferase activities induced by FGF2 were blocked by tyrosine kinase inhibitor herbimycin A, src-tyrosine kinase inhibitor PP1 and MAP kinase kinase inhibitor U0126. Gel shift analyses showed that FGF2 increased binding of FRE and AP1/GRE elements. Notably, the AP1/GRE-protein complexes were supershifted by Smad1 and c-Fos antibodies, c-Jun and Dlx5 antibodies disrupted the complexes formation, on the other hand AP1/GRE-protein complexes did not change by Runx2 antibody. These studies demonstrate that FGF2 stimulates BSP gene transcription by targeting the FRE and AP1/GRE elements in the rat BSP gene promoter.