CHARACTERIZATION OF TGF-BETA PROMOTERS

现在已经描述了TGF-β的五种不同亚型。三 这些称为TGF-Betas 1、2和3，在哺乳动物细胞中表达。的 三个不同的基因编码的蛋白质重叠的意义 活性可能存在于每个基因在不同条件下的差异表达中。 不同的生理条件。已经有大量证据表明 TGF-β基因表达的差异控制，在体外和体内， vivo.这个项目的目的是深入了解分子 哺乳动物TGF-β表达的转录调控机制 通过克隆和随后分析的启动子区的细胞， TGF-β 1、2和3的基因。启动子序列调节 TGF-β 1的表达已被证明含有AP-1位点， 结合Jun/Fos二聚体。通过评估转染的细胞的活性， TGF-β 1启动子的这些区域的嵌合构建体连接到 编码氯霉素乙酰转移酶的细菌基因，这些AP-1 这些位点直接参与TGF-β表达的调节， TGF-β本身，通过佛波酯，并通过Tax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 对人源性大肠杆菌的5'侧翼区进行了初步表征， TGF-β 2和TGF-β 3基因。TGF-β 2和3基因的调控区 与TGF-β 1基因的显著不同之处在于它们各自 含有紧邻转录起始位点上游的TATAA盒 并且每个都含有CRE或环AMP反应元件， 通过毛喉素介导这些基因的转录激活。本 研究旨在将这些影响与

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