Runx2参与调控Osterix启动子活性及其基因表达(英文)

Runx2 is Involved in Regulating Osterix Promoter Activity and Gene Expression

尽管Runx2和Osterix都是成骨细胞分化途径中关键的转录因子,但是Runx2是否能够调控Osterix,还不为所知.研究发现,在非成骨细胞系,无论是间充质干细胞还是已分化的细胞,以及成骨细胞系中,Runx2都能诱导Osterix的表达.同时Runx2能够上调3.2kb人的Osterix基因启动子活性.进一步实验证明,在这一段启动子中存在Runx2功能性的结合位点.因而,实验结果有力地支持了这样一个假设,即Runx2参与了Osterix基因的表达调控.瞬时转染和荧光素酶双报告分析结果显示,在非成骨细胞中,Osterix明显上调2.3kb的Ⅰ型胶原蛋白启动子活性,但Runx2却不能.这样的差别暗示,在成骨细胞分化过程中位于Runx2下游的转录因子Osterix是刺激Ⅰ型胶原蛋白基因表达所必需的.

Though Runx2 and Osterix are both key transcription factors in the pathway of osteoblast differentiation, whether Runx2 positively regulates Osterix being unknown. It was showed that Runx2 induced the gene expression of Osterix both in the non-osteoblastic cell lines, either pluripotent or differentiated, and in the osteoblastic cell lines. At the same time, the results also indicated that Runx2 up-regulated the activity of the 3.2 kb human Osterix promoter. Further experiments identified a highly conserved and functional Runx2 binding site ＂AGTGGTT＂ within the promoter. Thus the results support the hypothesis that Runx2 is involved in the regulation of the Osterix gene expression. Moreover, the transient transfection and dual-luciferase assay showed Osterix up-regulated the activity of the 2.3 kb type I collagen promoter in the non-osteoblastic cells, but Runx2 did not. This difference implies that Osterix, the down stream transcription factor of Runx2 during osteoblast differentiation, is needed to stimulate the osteoblast-specific gene expression of type Ⅰ collagen.