Germain S, Bonnet F, Fuchs S, Philippe J, Corvol P, Pinet F
INSERM Unit 36, Collège de France, Paris.
J Hypertens. 1999 Jul;17(7):899-905. doi: 10.1097/00004872-199917070-00005.
A silencer within the renin first intron (intron A) was identified using Calu-6 cells, a pulmonary carcinoma cell line which produced renin. In the present study, a dissection of the first intron was performed to determine precisely the cis-regulatory elements involved in the silencer transcriptional effects.
Intron A was completely sequenced to characterize potential binding sites for known transcription factors. Partial portions of intron A were subcloned upstream the 892 bp of the renin promoter and transfected in different models of renin-producing cells: primary culture of human chorionic cells, human Calu-6 cells and mouse As4.1 cells.
There is significant DNA homology (67%) between the 3' and 5' ends of the human and rat renin first intron. Several transcription factor binding sites identified in human first intron, but not in rat intron, do not contribute to the reported silencer activity. Transfections of renin/ luciferase constructs containing partial portions of first intron inserted upstream of the 892 bp in both renin-producing cells do not allow the precise characterization of cis-elements involved in the silencer effect.
The silencer located renin intron A is cell specific. The integrity of the human first intron seems necessary for its repressor activity on renin proximal promoter in renin-producing cells.
利用产生肾素的肺癌细胞系Calu-6细胞，鉴定出肾素第一内含子（内含子A）内的一个沉默子。在本研究中，对第一内含子进行剖析，以精确确定参与沉默子转录效应的顺式调控元件。
对内含子A进行全序列测序，以表征已知转录因子的潜在结合位点。将内含子A的部分片段亚克隆到肾素启动子892 bp的上游，并转染到不同的产生肾素的细胞模型中：人绒毛膜细胞原代培养物、人Calu-6细胞和小鼠As4.1细胞。
人和大鼠肾素第一内含子的3'端和5'端之间存在显著的DNA同源性（67%）。在人第一内含子中鉴定出的几个转录因子结合位点，但在大鼠内含子中未鉴定出，对报道的沉默子活性没有贡献。在两种产生肾素的细胞中，将含有插入到892 bp上游的第一内含子部分片段的肾素/荧光素酶构建体进行转染，无法精确表征参与沉默子效应的顺式元件。
位于肾素内含子A的沉默子具有细胞特异性。人第一内含子的完整性似乎是其在产生肾素的细胞中对肾素近端启动子产生抑制活性所必需的。
