Conserved mechanisms of Ras regulation of evolutionary related transcription factors, Ets1 and Pointed P2
Conserved mechanisms of Ras regulation of evolutionary related transcription factors, Ets1 and Pointed P2
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Ras 调控进化相关转录因子 Ets1 和 Pointed P2 的保守机制
作者：
C. Wasylyk;A. Bradford;A. Gutierrez;B. Wasylyk
RAS癌基因介导的细胞转化是由ETS基因家族成员介导的。为了分析调控机制，我们研究了RAS表达对几种ETS因子的激活作用。我们发现，Ha-RAS的表达强烈激活了F9 EC细胞中的Ets1p68和p54亚型以及Ets2。我们已经将Ets1 p68的RAS反应元件映射到两个结构域，RI+II和RIII。在RI+II中，苏氨酸82突变为丙氨酸使Ras的激活和MAP激酶的磷酸化都失效。苏氨酸82是在果蝇定点P2中保守的序列的一部分，P2是一种ETS蛋白，已被证明在果蝇细胞中介导RAS信号。我们扩展了这些进化相关蛋白质的比较，表明在哺乳动物细胞中，指向的P2被RAS激活，同源苏氨酸的突变取消激活。此外，我们还表明，定点P2类似于Ets1，因为它在Ets DNA结合域附近的相似位置上有保守的序列，负向地自动调节DNA结合。这些结果表明，果蝇和脊椎动物Ets1是进化相关的蛋白质，在MAP激酶下游具有显着保守的RAS调节机制。
Cell transformation by the Ras oncogene is mediated by members of the ets gene family. To analyse the mechanisms of regulation, we have studied activation of several ets factors by Ras expression. We show that expression of Ha-Ras strongly activates the Ets1 p68 and p54 isoforms and Ets2 in F9 EC cells. We have mapped the Ras responsive elements of Ets1 p68 to two domains, RI+II and RIII. Mutation of threonine 82 to alanine in RI+II abolishes both Ras activation and phosphorylation by MAP kinase. Threonine 82 is part of a sequence that is conserved in Drosophila Pointed P2, an ets protein that has been shown both genetically and biochemically to mediate Ras signalling in Drosophila cells. We extend the comparison of these evolutionary related proteins by showing that Pointed P2 is activated by Ras in mammalian cells and mutation of the homologous threonine abolishes activation. Furthermore, we show that Pointed P2 resembles Ets1, in that it has conserved sequences in a similar position adjacent to the ets DNA binding domain that negatively auto-regulates DNA binding. These results go towards showing that the Drosophila Pointed and vertebrate Ets1 are evolutionary related proteins that have remarkably conserved Ras regulatory mechanisms downstream from MAP kinase.