CHARACTERIZATION OF TGF-BETA PROMOTERS

现在已经描述了五种不同的转化生长因子-β亚型。其中三个 它们被称为转化生长因子-β1、2和3，在哺乳动物细胞中表达。这个 编码重叠蛋白的三个不同基因的意义 活性可能在于每个基因在不同条件下的差异表达 不同的生理条件。已经有确凿的证据表明 体外和体外对转化生长因子-β基因表达的差异性调控 活着。这个项目的目的是深入了解分子 哺乳动物中转化生长因子-β基因转录调控机制的研究 通过克隆和随后分析该基因的启动子区域 转化生长因子-β1、2和3的基因：启动子序列调控 已经证实，转化生长因子-β1的表达含有AP-1位点，该位点 结合Jun/Fos二聚体。通过对转染物活性的评价 转化生长因子-β1启动子这些区域的嵌合结构与 编码氯霉素乙酰转移酶的细菌基因，这些AP-1 有多个位点直接参与了转化生长因子-β的表达调控 转化生长因子-β本身，通过佛波酯和税务反式激活蛋白 人类逆转录病毒HTLV-I。最近，我们还克隆并完成了 人类5‘侧翼区的初步表征 转化生长因子-B2和转化生长因子-B3基因。转化生长因子-β2和3基因的调控区 与转化生长因子-β1基因显著不同的是，它们各自 在转录起始点的上游含有TATAA盒 并且每个都含有Cre或环状AMP反应元件，它们似乎 通过Forskolin介导这些基因的转录激活。现在时 研究的目的是将这些影响与

Five different isoforms of TGF-Beta have now been described. Three of these, called TGF-Betas 1, 2, and 3, are expressed in mammalian cells. The significance of three distinct genes encoding proteins of overlapping activity might lie in the differential expression of each gene under different physiological conditions. There is already substantial evidence of differential control of TGF-Beta gene expression both in vitro and in vivo. The purpose of this project is to gain insight into the molecular mechanisms of transcriptional control of TGF-Beta expression in mammalian cells by cloning and subsequent analysis of the promoter regions of the genes for TGF-Betas 1, 2, and 3. The promoter sequences regulating expression of,TGF-Beta1 have been demonstrated to contain AP-1 sites which bind the Jun/Fos dimer. By assessment of the activity of transfected chimeric constructs of these regions of the TGF-Beta1 promoter linked to the bacterial gene encoding chloramphenicol acetyltransferase, these AP-1 sites have been directly implicated in regulation of TGF-Beta expression by TGF-Beta itself, by phorbol ester, and by the Tax transactivating protein of the human retrovirus HTLV-I. Recently, we have also cloned and completed a preliminary characterization of the 5' flanking regions of the human TGF-B2 and TGF-B3 genes. The regulatory regions of the TGF-B2 and 3 genes differ significantly from that of the TGF-Beta1 gene in that they each contain TATAA boxes immediately upstream of the transcriptional start sites and each contain CRE or cyclic AMP response elements which appear to mediate transcriptional activation of these genes by forskolin. Present studies are aimed at correlating these effects on