Anderson G M, Shaw A R, Shafer J A
Department of Biological Chemistry, Merck Research Laboratories, West Point, Pennsylvania 19486.
J Biol Chem. 1993 Oct 25;268(30):22650-5.
A high level of plasma fibrinogen has been shown to be an important risk factor for myocardial infarction and stroke. Thus, we were prompted to investigate regulation of human fibrinogen biosynthesis, a process wherein expression of the B beta-chain of fibrinogen appears to be rate-limiting for fibrinogen secretion. Using electrophoretic mobility shift assays with synthetic probes representing portions of the human B beta-fibrinogen promoter, we have defined several elements that bind distinct classes of transcription factors present in human hepatoma cell nuclear extracts. The contribution of each element to promoter activity was demonstrated in transfection experiments using promoter-chloramphenicol acetyltransferase constructs and human hepatoma cells. Our observations indicate that two distinct sequence elements are required for maximal induction of transcription by interleukin-6. One of these sequences is an IL-6-RE core element similar to that reported for the rat alpha 2-macroglobulin promoter and the other is a binding site for the C/EBP family of transcription factors. We also report two additional elements, one negative- and one positive-acting, that bind novel sequence-specific factors.
高水平的血浆纤维蛋白原已被证明是心肌梗死和中风的重要危险因素。因此，我们着手研究人纤维蛋白原生物合成的调控，在这个过程中，纤维蛋白原Bβ链的表达似乎是纤维蛋白原分泌的限速步骤。通过使用代表人类Bβ-纤维蛋白原启动子部分的合成探针进行电泳迁移率变动分析，我们确定了几个与人类肝癌细胞核提取物中存在的不同类别的转录因子结合的元件。在使用启动子-氯霉素乙酰转移酶构建体和人类肝癌细胞的转染实验中，证明了每个元件对启动子活性的贡献。我们的观察结果表明，白细胞介素-6最大程度诱导转录需要两个不同的序列元件。其中一个序列是类似于大鼠α2-巨球蛋白启动子所报道的IL-6-RE核心元件，另一个是转录因子C/EBP家族的结合位点。我们还报告了另外两个元件，一个起负作用，一个起正作用，它们与新的序列特异性因子结合。
