Dorsman J C, Hagmeyer B M, Veenstra J, Elfferich P, Nabben N, Zantema A, van der Eb A J
Department of Medical Biochemistry, Sylvius Laboratory, Leiden, The Netherlands.
J Virol. 1995 May;69(5):2962-7. doi: 10.1128/JVI.69.5.2962-2967.1995.
The transforming E1A 12S and E1A 13S proteins of human adenovirus type 5 (Ad5) contain two and three conserved regions, respectively. In the present study, the contribution of sequences in the nonconserved N-terminal region of the E1A proteins to morphological transformation and to down-regulation of a number of mitogen-inducible genes was investigated. As described previously, transformation of NRK cells (an established normal rat kidney cell line) results in denser cell growth and a cuboidal cellular morphology. None of the cells expressing N-terminally mutated E1A proteins, however, show these transformed properties, which suggests an important role for sequences in that domain. The decrease in cyclin D1 levels requires exactly the same sequences. The ability to transform NRK cells and to reduce cyclin D1 levels does not correlate with the presence in the E1A proteins of binding domains for p300, CBP, p107, pRb, cyclin A, or cdk2. In contrast, down-regulation of expression of the JE gene in NRK cells and repression of transcription of the collagenase gene in human HeLa cells does correlate with the presence in the E1A proteins of an intact binding domain for p300 and CBP. The results suggest that the N-terminal domain of the E1A proteins can repress expression of cellular genes by at least two different mechanisms.
人5型腺病毒（Ad5）的转化型E1A 12S和E1A 13S蛋白分别含有两个和三个保守区域。在本研究中，研究了E1A蛋白非保守N端区域的序列对形态转化以及对一些丝裂原诱导基因下调的作用。如先前所述，NRK细胞（一种已建立的正常大鼠肾细胞系）的转化导致细胞生长更密集和呈现立方形细胞形态。然而，表达N端突变E1A蛋白的细胞均未表现出这些转化特性，这表明该结构域中的序列具有重要作用。细胞周期蛋白D1水平的降低需要完全相同的序列。转化NRK细胞和降低细胞周期蛋白D1水平的能力与E1A蛋白中是否存在p300、CBP、p107、pRb、细胞周期蛋白A或cdk2的结合结构域无关。相反，NRK细胞中JE基因表达的下调以及人HeLa细胞中胶原酶基因转录的抑制与E1A蛋白中存在完整的p300和CBP结合结构域相关。结果表明，E1A蛋白的N端结构域可通过至少两种不同机制抑制细胞基因的表达。
