Felts S J, Stoflet E S, Eggers C T, Getz M J
Department of Biochemistry and Molecular Biology, Mayo Clinic/Foundation, Rochester, Minnesota 55905, USA.
Biochemistry. 1995 Sep 26;34(38):12355-62. doi: 10.1021/bi00038a032.
Serum stimulation of quiescent mouse fibroblasts results in transcriptional activation of tissue factor (TF), the cellular initiator of the protease cascade leading to blood coagulation. In this study, we demonstrate that two AP-1 DNA-binding elements located 200-220 bp upstream of the transcription start site are both necessary and sufficient to confer serum inducibility to the TF gene promoter in fibroblasts. Analysis of AP-1 DNA-binding complexes indicates that the predominant form of AP-1 activity in quiescent cells consists of an unidentified Fos-related protein and JunD. While c-Fos is notably absent from these preexisting complexes, serum stimulation results in the rapid entry of c-Fos into the TF AP-1 DNA-binding complexes. A similar induction of c-Fos DNA-binding activity occurs in cells treated with recombinant growth factors such as platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF). Importantly, overexpression of JunD and c-Fos abrogates the requirement for serum in the stimulation of TF promoter activity in fibroblasts. Together, these data indicate that the entry of c-Fos into heterodimeric AP-1 DNA-binding complexes with JunD is a key event underlying serum-stimulated transcription of the TF gene in fibroblasts.
血清刺激静止的小鼠成纤维细胞会导致组织因子（TF）的转录激活，TF是启动蛋白酶级联反应导致血液凝固的细胞因子。在本研究中，我们证明位于转录起始位点上游200 - 220 bp处的两个AP - 1 DNA结合元件对于赋予成纤维细胞中TF基因启动子血清诱导性而言既是必需的也是充分的。对AP - 1 DNA结合复合物的分析表明，静止细胞中AP - 1活性的主要形式由一种未鉴定的Fos相关蛋白和JunD组成。虽然这些预先存在的复合物中明显不存在c - Fos，但血清刺激会导致c - Fos迅速进入TF AP - 1 DNA结合复合物。在用重组生长因子如血小板衍生生长因子（PDGF）和成纤维细胞生长因子（FGF）处理的细胞中也会发生类似的c - Fos DNA结合活性诱导。重要的是，JunD和c - Fos的过表达消除了成纤维细胞中血清对刺激TF启动子活性的需求。总之，这些数据表明c - Fos与JunD进入异二聚体AP - 1 DNA结合复合物是成纤维细胞中血清刺激TF基因转录的关键事件。
