Thompson M J, Roe M W, Malik R K, Blackshear P J
Howard Hughes Medical Institute Laboratory, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.
J Biol Chem. 1994 Aug 19;269(33):21127-35.
Rapid, transient induction of c-fos transcription follows treatment of cells with insulin and other growth factors. This is mediated through the serum response element (SRE), which binds the serum response factor (SRF), as well as accessory factors such as p62 ternary complex factor. Using a gel shift assay we found that formation of the ternary complex increased transiently within 2 min of insulin or phorbol ester treatment of several insulin-sensitive cell lines. However, mutations that prevented formation of this ternary complex did not inhibit insulin- or phorbol ester-stimulated induction of c-fos transcription in these cell lines. We also identified a novel SRF-containing multiprotein complex that forms on the SRE within 2 min following insulin, phorbol ester, or other growth factor treatment. Formation of this novel complex, called band 3, occurred rapidly and transiently, with a time course parallel to the induction of c-fos transcription. Band 3 also formed with gamma-actin and zif268/3 SRE probes. Methylation and carboxy ethylation interference analysis, as well as extensive SRE mutagenesis, suggest that only the SRF directly contacts the SRE in forming band 3. Formation of this novel complex appears to involve protein-protein interactions between SRF and other nuclear protein(s) that may play a role in growth factor stimulation of c-fos transcription.
用胰岛素和其他生长因子处理细胞后，c-fos转录会迅速、短暂地被诱导。这是通过血清反应元件（SRE）介导的，该元件与血清反应因子（SRF）以及诸如p62三元复合因子等辅助因子结合。使用凝胶迁移试验，我们发现，在对几种胰岛素敏感细胞系进行胰岛素或佛波酯处理后的2分钟内，三元复合物的形成会短暂增加。然而，阻止这种三元复合物形成的突变并没有抑制这些细胞系中胰岛素或佛波酯刺激的c-fos转录诱导。我们还鉴定出一种新型的含SRF多蛋白复合物，它在胰岛素、佛波酯或其他生长因子处理后的2分钟内在SRE上形成。这种称为条带3的新型复合物的形成迅速且短暂，其时间进程与c-fos转录的诱导平行。条带3也能与γ-肌动蛋白和zif268/3 SRE探针形成。甲基化和羧基乙基化干扰分析以及广泛的SRE诱变表明，在形成条带3时只有SRF直接与SRE接触。这种新型复合物的形成似乎涉及SRF与其他核蛋白之间的蛋白质-蛋白质相互作用，这些核蛋白可能在生长因子对c-fos转录的刺激中发挥作用。
