转录因子Osterix对成骨细胞Col1a1基因的反式激活作用

Trans-activation of Col1a1 Promoter by Osterix During Osteocyte Differentiation

Osterix(Osx)是一种具有锌指结构的转录因子,对骨形成十分重要.但到目前为止,直接接受Osterix调控的靶基因尚不清楚.用骨形态发生蛋白2(bone morphogenetic protein 2,BMP2)诱导原代培养小鼠成骨细胞的骨分化,定量RT-PCR检测Ⅰ型胶原蛋白(collagen Ⅰ a1,Col1a1)与Osx的转录水平.结果发现,二者的转录时相具有相同的变化模式.为了确定二者之间的关系,采用腺病毒表达系统在原代成骨细胞中过表达Osx.数据表明,Osx能够明显上调Col1a1的转录水平.用EMSA(electromobility shift assay)检测这些过表达Osx基因的成骨细胞核抽提物,迁移条带的出现表明,Osx能够直接与Col1a1的启动子相结合.结果提示,在原代培养的成骨细胞中,Osterix通过直接与启动子相结合,调控Col1a1基因的转录.

Osterix （Osx） is a zinc-finger-containing transcription factor playing an important role in osteogenesis, but controlling down target genes of Osx remain to be unclear. Bone morphogenetic protein 2 （BMP 2） was used to induce osteocyte differentiation of primarily cultured mouse osteoblasts, transcriptional level of Coil α 1 and Osx were determined by quantitative RT-PCR. As a result, the time course of the transcriptional level of these two genes shared the same pattern. To determine their relationship, Osx was overexpressed in the primary osteoblasts by using adenovirus system. The data showed that Osx could upregnlated the transcription level of Col 1 α 1 significantly. Nuclear extracts of the osteoblast, in wich Osx was overexpressed, were analyzed by electromobility shift assay （EMSA）, the presence of the shift band demonstrated the binding of Osx to the promoter of Col 1 α 1. Our results suggest that, in the primarily cultured mouse osteoblasts, Osx directly regulated the transcription of Col 1 α 1 through binding to its promoter.