TRANSCRIPTION STIMULATION BY ADENOVIRUS E1A PROTEIN

腺病毒E1 A蛋白直接参与致癌转化， 腺病毒。 它是一种具有结构和功能的核蛋白， 与重要的人类癌基因c-myc的产物同源。 表达 E1 A蛋白的表达对基因的转录有很大的刺激作用 通过转染或病毒感染引入哺乳动物细胞。 的 E1 A蛋白功能的分子机制尚不清楚。 最近我们 在确定转录诱导机制方面取得了突破 E1 A蛋白 我们发现E1 A蛋白的表达极大地刺激了 由RNA聚合酶III转录的基因的转录以及RNA 聚合酶II。 具有重要的现实意义，这增加了 在体内观察到的转录活性也在体外观察到， 从腺病毒感染和转化的细胞制备的提取物。 这是 这是E1 A蛋白首次诱导转录活性的增加， 已经在体外观察到。 它开启了酶学，蛋白质 分馏和纯化研究，这应该是非常翔实的。 初步结果表明，E1 A蛋白在体外不刺激 直接转录。 相反，它在体内的表达导致了 所需的限制性转录因子的活性增加， RNA聚合酶III前起始复合物TF IIIC的形成。 我们 我建议继续进行这些酶学研究，以证实这种表达 的E1 A蛋白确实增加TF IIIC活性，如果确实如此， 它的机制。 TF IIIC的功能测定增加 由于E1 A表达，或者如果TF的翻译后修饰 诱导IIIC，从而增加其比活性。 基于这些 结果，我们还建议，以确定E1 A蛋白的影响， RNA转录所需转录因子的活性 聚合酶II。 这些研究可能表明E1 A的生物化学活性 蛋白质，因此是核转化蛋白。

Adenovirus E1A protein is directly involved in oncogenic transformation by adenovirus. It is a nuclear protein with structural and functional homology to the product of the important human oncogene c-myc. Expression of E1A protein results in a great stimulation of the transcription of genes introduced into mammalian cells by transfection or viral infection. The molecular mechanism of E1A protein function is not known. Recently we have made a breakthrough in determining the mechanism of transcription induction by E1A protein. We found that expression of E1A protein greatly stimulates the transcription of genes transcribed by RNA polymerase III as well as RNA polymerase II. Of great practical significance, this increased transcriptional activity observed in vivo is also observed in vitro with extracts prepared from adenovirus infected and transformed cells. This is the first time an E1A protein-induced increase in transcriptional activity has been observed in vitro. It opens the door to enzymological, protein fractionation and purification studies which should be very informative. Preliminary results indicate that E1A protein does not stimulate in vitro transcription directly. Rather, its expression in vivo leads to an increase in the activity of the limiting transcription factor required for the formation of RNA polymerase III pre-initiation complexes, TF IIIC. We propose to continue these enzymological studies to confirm that expression of E1A protein does increase TF IIIC activity, and if it does, to determine the mechanism by which it does. Functional assays for TF IIIC is increased as a result of E1A expression, or if post-translational modifications of TF IIIC are induced which increase its specific activity. Based on these results, we also propose to determine the affect of E1A protein on the activity of transcription factors required for transcription by RNA polymerase II. These studies may suggest a biochemical activity for E1A protein, and hence for a nuclear transforming protein.