Hosler B A, Rogers M B, Kozak C A, Gudas L J
Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115.
Mol Cell Biol. 1993 May;13(5):2919-28. doi: 10.1128/mcb.13.5.2919-2928.1993.
The message for the zinc finger gene Rex-1 (Zfp-42) is expressed in undifferentiated murine F9 teratocarcinoma cells and embryonic stem cells. Expression of Rex-1 is reduced at the transcriptional level when F9 cells are induced by the addition of retinoic acid (RA) to differentiate. We have isolated genomic DNA for the Rex-1 gene (Zfp-42), characterized the gene's structure, and mapped the gene to mouse chromosome 8. Promoter elements contributing to the regulation of the Rex-1 promoter in F9 cells have been identified. A region required for Rex-1 promoter activity in F9 stem cells contains an octamer motif (ATTTGCAT) which is a binding site for octamer transcription factor members of the POU domain family of DNA-binding proteins. Rex-1 reporter plasmids including this octamer site also exhibited reduced expression in F9 cells treated with RA. Thus, the octamer motif is a regulatory element required for the activity of the Rex-1 promoter in F9 stem cells, and this motif contributes to the negative regulation by RA of the transcription of the Rex-1 gene. As an initial confirmation of the in vivo relevance of the isolated fragment, a larger Rex-1 promoter fragment, also containing the octamer site, was able to promote expression of the bacterial lacZ gene in mouse embryos at the morula stage.
锌指基因Rex-1（Zfp-42）的信使核糖核酸在未分化的小鼠F9畸胎瘤细胞和胚胎干细胞中表达。当通过添加视黄酸（RA）诱导F9细胞分化时，Rex-1的表达在转录水平上降低。我们已经分离出Rex-1基因（Zfp-42）的基因组DNA，对该基因的结构进行了表征，并将该基因定位到小鼠8号染色体上。已经确定了在F9细胞中有助于调节Rex-1启动子的启动子元件。F9干细胞中Rex-1启动子活性所需的区域包含一个八聚体基序（ATTTGCAT），它是DNA结合蛋白POU结构域家族的八聚体转录因子成员的结合位点。包含这个八聚体位点的Rex-1报告质粒在用RA处理的F9细胞中也表现出表达降低。因此，八聚体基序是F9干细胞中Rex-1启动子活性所需的调节元件，并且该基序有助于RA对Rex-1基因转录的负调控。作为对分离片段体内相关性的初步证实，一个更大的也包含八聚体位点的Rex-1启动子片段能够在桑椹胚阶段的小鼠胚胎中促进细菌lacZ基因的表达。
