Department of Microbiology & Immunology, The University of Western Ontario, London Regional Cancer Centre, Ontario, Canada.
J Virol. 2013 Sep;87(18):10348-55. doi: 10.1128/JVI.00786-13. Epub 2013 Jul 17.
Human adenovirus E1A makes extensive connections with the cellular protein interaction network. By doing so, E1A can manipulate many cellular programs, including cell cycle progression. Through these reprogramming events, E1A functions as a growth-promoting oncogene and has been used extensively to investigate mechanisms contributing to oncogenesis. Nevertheless, it remains unclear how the C-terminal region of E1A contributes to oncogenic transformation. Although this region is required for transformation in cooperation with E1B, it paradoxically suppresses transformation in cooperation with activated Ras. Previous analysis has suggested that the interaction of E1A with CtBP plays a pivotal role in both activities. However, some C-terminal mutants of E1A retain CtBP binding and yet exhibit defects in transformation, suggesting that other targets of this region are also necessary. To explore the roles of these additional factors, we performed an extensive mutational analysis of the C terminus of E1A. We identified key residues that are specifically required for binding all known targets of the C terminus of E1A. We further tested each mutant for the ability to both localize to the nucleus and transform primary rat cells in cooperation with E1B-55K or Ras. Interaction of E1A with importin α3/Qip1, dual-specificity tyrosine-regulated kinase 1A (DYRK1A), HAN11, and CtBP influenced transformation with E1B-55K. Interestingly, the interaction of E1A with DYRK1A and HAN11 appeared to play a role in suppression of transformation by activated Ras whereas interaction with CtBP was not necessary. This unexpected result suggests a need for revision of current models and provides new insight into transformation by the C terminus of E1A.
人腺病毒 E1A 与细胞蛋白相互作用网络建立了广泛的联系。通过这种方式，E1A 可以操纵许多细胞程序，包括细胞周期进程。通过这些重编程事件，E1A 作为促进生长的致癌基因发挥作用，并被广泛用于研究导致致癌的机制。然而，E1A 的 C 端区域如何促进致癌转化仍不清楚。尽管该区域与 E1B 合作是转化所必需的，但它与激活的 Ras 合作却抑制了转化。先前的分析表明，E1A 与 CtBP 的相互作用在这两种活性中都起着关键作用。然而，E1A 的一些 C 端突变体保留了与 CtBP 的结合，但在转化中存在缺陷，这表明该区域的其他靶标也是必需的。为了探讨这些额外因素的作用，我们对 E1A 的 C 端进行了广泛的突变分析。我们确定了关键残基，这些残基专门用于结合 E1A C 端的所有已知靶标。我们进一步测试了每个突变体与 E1B-55K 或 Ras 合作定位到核内和转化原代大鼠细胞的能力。E1A 与输入蛋白 α3/Qip1、双特异性酪氨酸调节激酶 1A（DYRK1A）、HAN11 和 CtBP 的相互作用影响了与 E1B-55K 的转化。有趣的是，E1A 与 DYRK1A 和 HAN11 的相互作用似乎在抑制激活的 Ras 转化中发挥作用，而与 CtBP 的相互作用不是必需的。这一意外结果表明需要对当前模型进行修订，并为 E1A 的 C 端转化提供了新的见解。
