Signaling network of Mec1 in DNA damage response

描述（由申请人提供）：对DNA损伤的反应由检查点途径控制，该途径从酵母到人都是保守的。申请人的长期目标是确定ATR及其同源物的功能和调节，其涉及DMA损伤检查点。MEC 1在芽殖酵母中编码ATR同源物。ATR和Mec 1蛋白被认为是损伤传感器。我们已经证明，Mec 1与Ddc 2相互作用，并与DNA损伤位点相关。我们的初步结果表明，Mec 1成为激活后，与DMA损伤的网站。 检查点介质包括哺乳动物中的BRCA 1、53 BP 1和MDC 1以及芽殖酵母中的Rad 9。像哺乳动物介质一样，Rad 9定位于DNA损伤的位点。哺乳动物Chk 2激酶及其芽殖酵母同源物Rad 53是信号转导子。磷酸化的Rad 9与Rad 53相互作用，并且这种Rad 9-Rad 53相互作用涉及Rad 53活化。我们已经表明，Mec 1磷酸化Rad 9，并促进Rad 9与DNA损伤位点的关联。DNA损伤检查点途径也有助于损伤修复本身。DNA聚合酶C参与DNA合成以绕过DNA损伤。DNA聚合酶zeta由芽殖酵母中的Rev 3和Rev 7蛋白组成。我们的初步研究表明，Mec 1磷酸化Rev 7，并控制其与DNA损伤位点的关联。根据这些观察，我们提出确定Mec 1-Ddc 2复合物在DNA损伤位点（Aim 1）的活化机制，以揭示磷酸化的Rad 9在DNA损伤位点（Aim 2）的功能，并确定Rev 3-Rev 7 DNA聚合酶的Meet依赖性磷酸化中的作用（Aim 3）。检查点反应的失败被认为是染色体不稳定的主要原因，这导致高等真核生物中的癌症。因此，更好地了解DNA损伤检查点应该使我们能够预防癌细胞的发展。

DESCRIPTION (provided by applicant): The responses to DNA damage are controlled by checkpoint pathways, which are conserved from yeast to human. The applicant's long-term aim is to define the function and regulation of ATR and its homologs which are involved with DMA damage checkpoints. MEC1 encodes an ATR homolog in budding yeast. ATR and Mec1 proteins are considered as damage sensor. We have shown that Mec1 interacts with Ddc2, and associates with sites of DNA damage. Our preliminary results suggest that Mec1 becomes activated after association with the site of DMA damage. Checkpoint mediators include BRCA1, 53BP1 and MDC1 in mammals and Rad9 in budding yeast. Like the mammalian mediators, Rad9 localizes to sites of DNA damage. Mammalian Chk2 kinase and its budding yeast homolog Rad53 are signal transducers. Phosphorylated Rad9 interacts with Rad53, and this Rad9-Rad53 interaction is implicated in Rad53 activation. We have shown that Mec1 phosphorylates Rad9 and promotes Rad9 association with sites of DNA damage. The DNA damage checkpoint pathway also contributes to damage repair itself. DNA polymerase C, is involved in DNA synthesis to bypass DNA damage. DNA polymerase zeta consists of Rev3 and Rev7 proteins in budding yeast. Our preliminary studies suggest that Mec1 phosphorylates Rev7 and controls its association with sites of DNA damage. From these observations, we propose to determine the mechanism of activation of the Mec1-Ddc2 complex at sites of DNA damage (Aim1), to uncover functions of phosphorylated Rad9 at sites of DNA damage (Aim2), and determine roles in Meet -dependent phosphorylation of the Rev3-Rev7 DNA polymerase (Aim 3). The failure of the checkpoint response has been implicated as a major cause of chromosomal instability, which leads to cancer in higher eukaryotes. A better understanding of DNA damage checkpoint thus should allow us to prevent the development of cancer cells.