Hawker K L, Vass J K, Ozanne B W
Beatson Institute for Cancer Research, CRC Beatson Laboratories, Bearsden, Glasgow, UK.
Oncogene. 1996 Jul 18;13(2):283-92.
Increased AP-1 DNA-binding activity, in the context of TRE-binding, is not a consequence of Fos transformation. In this report we investigate the possibility of a change in binding site preference by vFosAP-1 compared with AP-1 from an untransformed cell. Fos binding sites were immunoselected from random sequence oligonucleotides using a pan Fos anti-serum with nuclear protein from quiescent FBRp75v-fos-transformed (FBR) and normal (208F) rat fibroblasts. The selected oligonucleotides were aligned by computer and a consensus described for the sequences bound by AP-1 from the two cell lines. The vFos binding site is shown to be a consensus TRE, whereas the sequence ACCACATC is described as the cellular Fos protein family consensus. We demonstrate that sequences differing from the TRE consensus can bind AP-1 and direct transcription. AP-1 DNA-binding activity differs between normal and transformed cells with several of the selected oligonucleotides. These sequences also demonstrate differential transcriptional activation between normal and transformed cells. In particular, the 208F consensus has no transcriptional activity in FBR cells. Further, EGF differentially influences the transcriptional activity of the oligonucleotides in 208F and FBR cells. Our results suggest that AP-1 may change its preferred binding site depending on the proteins available at any given time, the sequences flanking a non-consensus TRE or even the environment in which the cell exists. These differences in binding site preference and transcriptional activation may result in the increased transforming ability of the v-fos oncogene compared with the c-fos proto-oncogene and may extend the potential target genes beyond those with an AP-1 consensus binding site.
在TRE结合的情况下，AP-1 DNA结合活性的增加并非Fos转化的结果。在本报告中，我们研究了与未转化细胞中的AP-1相比，vFosAP-1结合位点偏好发生变化的可能性。使用泛Fos抗血清从随机序列寡核苷酸中免疫选择Fos结合位点，该抗血清与来自静止的FBRp75v-fos转化（FBR）和正常（208F）大鼠成纤维细胞的核蛋白结合。通过计算机对所选寡核苷酸进行比对，并描述了两种细胞系中AP-1结合序列的共有序列。vFos结合位点显示为一个共有TRE，而序列ACCACATC被描述为细胞Fos蛋白家族的共有序列。我们证明，与TRE共有序列不同的序列可以结合AP-1并指导转录。正常细胞和转化细胞之间的AP-1 DNA结合活性在几种所选寡核苷酸上存在差异。这些序列在正常细胞和转化细胞之间也表现出不同的转录激活。特别是，208F共有序列在FBR细胞中没有转录活性。此外，表皮生长因子（EGF）对208F和FBR细胞中寡核苷酸的转录活性有不同影响。我们的结果表明，AP-1可能会根据任何给定时间可用的蛋白质、非共有TRE侧翼的序列，甚至细胞所处的环境改变其偏好的结合位点。与c-fos原癌基因相比，v-fos癌基因结合位点偏好和转录激活的这些差异可能导致其转化能力增强，并可能将潜在靶基因扩展到那些具有AP-1共有结合位点之外的基因。
