Asiedu C K, Scotto L, Assoian R K, Ehrlich M
Department of Biochemistry SL43, Tulane Medical School, New Orleans, LA 70112.
Biochim Biophys Acta. 1994 Sep 13;1219(1):55-63. doi: 10.1016/0167-4781(94)90246-1.
Transcription of the human gene encoding transforming growth factor beta 1 (TGF-beta 1), which is a key regulator of cell growth and differentiation, is inducible by phorbol esters. DNA sequences resembling phorbol ester response elements (TREs) are present upstream and downstream of this gene. TREs are recognized by proteins from the AP-1 family of transcription factors. We examined a 16 basepair (bp) sequence downstream of the TGF-beta 1 gene that contains three putative TREs. This sequence had been shown to stimulate reporter gene expression from a downstream location in response to phorbol ester treatment. Electrophoretic mobility shift assays suggest that minor proteins from the related AP-1 and CREB families of transcription factors bind to the overlapping TREs within the 16 bp element. A site beginning at the end of this 16 bp element matches the consensus sequence of a DNA-binding protein called MDBP and was shown to bind to this protein. When the intact MDBP site was present in a reporter gene construct in addition to the TREs, the phorbol ester-induced stimulation of reporter gene expression was no longer observed. This suggests that MDBP can counteract the stimulation of transcription by AP-1/CREB-like proteins binding to this downstream enhancer element.
编码转化生长因子β1（TGF-β1）的人类基因的转录可被佛波酯诱导，TGF-β1是细胞生长和分化的关键调节因子。该基因的上游和下游存在类似于佛波酯反应元件（TREs）的DNA序列。TREs可被转录因子AP-1家族的蛋白质识别。我们研究了TGF-β1基因下游一个16碱基对（bp）的序列，该序列包含三个假定的TREs。已证明该序列在佛波酯处理后可从下游位置刺激报告基因表达。电泳迁移率变动分析表明，转录因子相关AP-1和CREB家族的次要蛋白质与16 bp元件内重叠的TREs结合。该16 bp元件末端开始的一个位点与一种名为MDBP的DNA结合蛋白的共有序列匹配，并被证明可与该蛋白结合。当完整的MDBP位点除TREs外还存在于报告基因构建体中时，不再观察到佛波酯诱导的报告基因表达刺激。这表明MDBP可抵消AP-1/CREB样蛋白与该下游增强子元件结合对转录的刺激作用。
