Somasundaram K, Jayaraman G, Williams T, Moran E, Frisch S, Thimmapaya B
Lurie Cancer Center, Northwestern University Medical School, Chicago, IL 60611, USA.
Proc Natl Acad Sci U S A. 1996 Apr 2;93(7):3088-93. doi: 10.1073/pnas.93.7.3088.
Adenovirus E1A 243-amino acid protein can repress a variety of enhancer -linked viral and cellular promoters. This repression is presumed to be mediated by its interaction with and sequestration of p3OO, a transcriptional coactivator. Type IV 72-kDa collagenase is one of the matrix metalloproteases that has been implicated in differentiation, development, angiogenesis, and tumor metastasis. We show here that the cell type-specific transcription factor AP-2 is an important transcription factor for the activation of the type IV 72-kDa collagenase promoter and that adenovirus E1A 243-amino acid protein represses this promoter by targeting AP-2. Glutathione S-transferase-affinity chromatography studies show that the E1A protein interacts with the DNA binding/dimerization region of AP-2 and that the N-terminal amino acids of E1A protein are required for this interaction. Further, E1A deletion mutants which do not bind to p3OO can repress this collagenase promoter as efficiently as the wildtype E1A protein. Because the AP-2 element is present in a variety of viral and cellular enhancers which are repressed by E1A, these studies suggest that E1A protein can repress cellular and viral promoter/enhancers by forming a complex with cellular transcription factors and that this repression mechanism may be independent of its interaction with p3OO.
腺病毒E1A 243个氨基酸的蛋白能抑制多种与增强子相连的病毒和细胞启动子。这种抑制作用据推测是通过其与转录共激活因子p300的相互作用及隔离来介导的。IV型72-kDa胶原酶是基质金属蛋白酶之一，与分化、发育、血管生成及肿瘤转移有关。我们在此表明，细胞类型特异性转录因子AP-2是激活IV型72-kDa胶原酶启动子的重要转录因子，且腺病毒E1A 243个氨基酸的蛋白通过靶向AP-2来抑制该启动子。谷胱甘肽S-转移酶亲和层析研究表明，E1A蛋白与AP-2的DNA结合/二聚化区域相互作用，且这种相互作用需要E1A蛋白的N端氨基酸。此外，不与p300结合的E1A缺失突变体能够像野生型E1A蛋白一样有效地抑制该胶原酶启动子。由于AP-2元件存在于多种被E1A抑制的病毒和细胞增强子中，这些研究提示，E1A蛋白可通过与细胞转录因子形成复合物来抑制细胞和病毒启动子/增强子，且这种抑制机制可能独立于其与p300的相互作用。
