Mizuguchi J, Hu C H, Cao Z, Loeb K R, Chung D W, Davie E W
Department of Biochemistry, University of Washington, Seattle 98195-7350, USA.
J Biol Chem. 1995 Nov 24;270(47):28350-6. doi: 10.1074/jbc.270.47.28350.
The 5'-flanking region of the gene coding for the gamma chain of human fibrinogen was characterized for its promoter activity. Reporter gene studies using chloramphenicol acetyltransferase as the indicator along with mutations in the DNA showed that a TATA-like sequence (-20 to -23 base pairs (bp)), a CAAT-like sequence (-54 to -57 bp), and an upstream stimulatory factor (USF) binding site (-66 to -77 bp) constitute a minimal promoter that mediates liver-specific expression of the gene. Electrophoretic gel mobility assays and antibody binding studies confirmed the interaction of USF with the binding site. An IL-6 responsive element with a sequence of CTGGAA located at -301 to -306 bp was shown to be a functional element in the IL-6 response. In contrast to the IL-6 responsive elements in the human alpha- and beta-fibrinogen genes, the element in the gene for the gamma chain of human fibrinogen was unaffected by the presence or elevated levels of the beta or delta isoforms of the CCAAT/enhancer binding proteins. A negative element with sequence homology to several silencer elements was also identified in the region of -348 to -390 bp of the gene for the gamma chain of human fibrinogen. A comparison of the regulatory elements in the genes coding for all three chains in fibrinogen is also presented.
对人纤维蛋白原γ链编码基因的5'侧翼区域进行了启动子活性特征分析。使用氯霉素乙酰转移酶作为指示物的报告基因研究以及DNA中的突变表明，一个类似TATA的序列（-20至-23碱基对（bp））、一个类似CAAT的序列（-54至-57 bp）和一个上游刺激因子（USF）结合位点（-66至-77 bp）构成了一个最小启动子，介导该基因的肝脏特异性表达。电泳凝胶迁移率分析和抗体结合研究证实了USF与结合位点的相互作用。一个位于-301至-306 bp、序列为CTGGAA的白细胞介素-6反应元件被证明是白细胞介素-6反应中的一个功能元件。与人类α-和β-纤维蛋白原基因中的白细胞介素-6反应元件不同，人纤维蛋白原γ链基因中的元件不受CCAAT/增强子结合蛋白β或δ异构体的存在或水平升高的影响。在人纤维蛋白原γ链基因的-348至-390 bp区域还鉴定出了一个与几个沉默子元件具有序列同源性的负元件。还对纤维蛋白原所有三条链编码基因中的调控元件进行了比较。
