Signaling network of Mec1 in DNA damage response

描述(申请人提供)：对DNA损伤的反应由检查点途径控制，从酵母到人类都是保守的。申请人的长期目标是界定与DMA损坏检查点有关的ATR及其同系物的功能和监管。MEC1在萌芽酵母中编码ATR同源物。ATR和Mec1蛋白被认为是损伤感受器。我们已经证明了Mec1与Ddc2相互作用，并与DNA损伤部位相关。我们的初步结果表明，Mec1在与DMA损伤部位相关联后被激活。 检查点调节因子在哺乳动物中包括BRCA1、53BP1和MDC1，在芽殖酵母中包括Rad9。像哺乳动物的介体一样，Rad9定位于DNA损伤的部位。哺乳动物Chk2激酶及其芽生酵母同系物Rad53是信号转导分子。磷酸化的Rad9与Rad53相互作用，这种Rad9-Rad53的相互作用与Rad53的激活有关。我们已经证明，Mec1使Rad9磷酸化，并促进Rad9与DNA损伤部位的联系。DNA损伤检查点通路本身也有助于损伤修复。DNA聚合酶C参与DNA合成，绕过DNA损伤。芽殖酵母中的DNA聚合酶ZetA由Rev3和Rev7蛋白组成。我们的初步研究表明，Mec1使Rev7磷酸化，并控制其与DNA损伤部位的关联。通过这些观察，我们建议确定Mec1-Ddc2复合体在DNA损伤位点(Aim1)的激活机制，揭示磷酸化的Rad9在DNA损伤位点(AIM2)的功能，并确定在Rev3-Rev7 DNA聚合酶(Aim3)的相遇依赖的磷酸化中的作用(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，而染色体不稳定会导致高等真核生物中的癌症。因此，更好地了解DNA损伤检查点应该可以防止癌细胞的发展。

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.