Ponticos Markella, Abraham David, Alexakis Catherine, Lu Qi-Long, Black Carol, Partridge Terence, Bou-Gharios George
Muscle Cell Biology Group, MRC Clinical Science Centre, Imperial College, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.
Matrix Biol. 2004 Feb;22(8):619-28. doi: 10.1016/j.matbio.2003.12.002.
An enhancer region in the type I collagen alpha 2 chain (pro-Col1a2) promoter has been previously identified approximately -17 kb away from the transcription start site. This upstream region termed the far-upstream-enhancer contains three DNAse I hypersensitive sites and has been shown to be conserved between mouse and human genes. In this study, we used transgenic mice harbouring the complete promotor sequence of the pro-Col1a2 gene up to -17 kb to examine the role of this enhancer in the expression and regulation of the collagen gene during development and in adult tissues pre and post injury. By careful histological mapping of the collagen type I endogenous gene distribution with that of the transgene driven by the mouse far upstream enhancer, we are able to show that in early days of collagen expression, E8.5-9.5, the endogenous gene preceded transgene expression. However, by E11.5 the overall pattern becomes synchronous with a few exceptions. In adult tissue, both endogenous and transgene expression are attenuated and both are reactivated in parallel in various organs by physical injury or fibrogenic cytokine injection. These findings suggest that the enhancer is central to the activation of the collagen type I and that mice harbouring this enhancer/reporter provide a useful model to follow collagen gene transcription activity and for investigating cellular activity in tissue fibrosis.
I型胶原蛋白α2链（前胶原1α2）启动子中的一个增强子区域先前已被确定，距离转录起始位点约-17 kb。这个上游区域被称为远上游增强子，包含三个脱氧核糖核酸酶I超敏位点，并且已被证明在小鼠和人类基因之间是保守的。在本研究中，我们使用了携带前胶原1α2基因完整启动子序列直至-17 kb的转基因小鼠，以研究该增强子在发育过程中以及成年组织损伤前后胶原蛋白基因表达和调控中的作用。通过仔细的组织学定位I型胶原蛋白内源基因的分布以及由小鼠远上游增强子驱动的转基因的分布，我们能够表明在胶原蛋白表达的早期，即E8.5-9.5，内源基因的表达先于转基因。然而，到E11.5时，总体模式除了少数例外变得同步。在成年组织中，内源基因和转基因的表达均减弱，并且在受到物理损伤或注射促纤维化细胞因子后，二者在各个器官中均同时重新激活。这些发现表明，该增强子对于I型胶原蛋白的激活至关重要，并且携带该增强子/报告基因的小鼠为追踪胶原蛋白基因转录活性以及研究组织纤维化中的细胞活性提供了一个有用的模型。
