Role of an unusual GTPase in DNA damage response and carcinogenesis

项目总结 我们最近发现了一个新的p53促生存信号通路，涉及上调表达。 P53靶基因或DNA损伤检查点基因，这些基因可以影响 依赖P53的DNA损伤中细胞死亡和停滞/衰老之间的平衡 回应。我们已经确定RhoE基因是P53和P53的一个新的转录靶点。 DNA损伤。我们发现DNA损伤会触发肌动蛋白解聚，导致 P53依赖的RhoE激活的应激纤维分解。RhoE是最近添加的 属于小GTP酶超家族，与RhoA、B和C有最强的同源性。 尽管有如此高的同源性，RhoE仍有几个不寻常的特性将其与 其他的Rho蛋白。与其他Rho蛋白不同，RhoE似乎是唯一的Rho家族 对DNA损伤作出转录反应的蛋白质，可导致肌动蛋白应激丢失 纤维。我们假设RhoE蛋白对于携带wtp53的癌细胞的生存是必不可少的。 通过抑制促凋亡蛋白的活性，同时增强细胞周期蛋白的功能 生存蛋白对暴露的DNA损伤的反应。 这项建议的主要目的是了解一个小的GTP酶，RhoE， 作为P53依赖的DNA损伤的新靶基因并翻译我们的基本 了解RhoE在人癌细胞凋亡中的细胞存活功能 包括乳腺癌细胞。尽管RhoE在DNA损伤反应中的生物学作用 途径还没有定义，我们的初步数据表明反式激活 RhoE基因受P53依赖的DNA损伤，其作为肌动蛋白关键组织者的潜在作用 细胞骨架及其在DNA损伤诱导的细胞存活中的特殊作用 我们。越来越多的证据表明，通过Rho蛋白发出的异常信号 与肿瘤发生和癌变的各个步骤密切相关。 在这项应用中，将使用生化和遗传方法的组合来(I) RhoE在P53依赖的细胞结局和DNA损伤中的作用 应激反应；(2)确定和描述RhoE互动伙伴，这将界定 影响RhoE介导的细胞存活和p53依赖的细胞死亡的分子途径 对基因毒性应激的反应；iii)确定ROCK 1是否是 JNK介导的细胞死亡信号；以及(Iv)确定RhoE在DNA损伤中的作用 检验点信号和细胞存活信号在小鼠基因敲除方法中的应用。

PROJECT SUMMARY We have recently identified a novel p53 pro-survival signaling pathway involving upregulation of p53 target genes or DNA damage checkpoint genes, which can influence the balance between cell death and arrest/senescence in a p53 dependent DNA damage response. We have identified the RhoE gene as a novel transcriptional target of p53 and DNA damage. We found that DNA damage triggers actin depolymerization, resulting in stress-fiber disassembly through p53-dependent RhoE activation. RhoE is a recent addition of the small GTPases superfamily and has the strongest homology to RhoA, B, and C. Despite this high homology, RhoE has several unusual properties which distinguish it from the other Rho proteins. Unlike other Rho proteins, RhoE seems to be only Rho family protein transcriptionally responsive to DNA damage that can induce loss of actin stress fibers. We hypothesize that RhoE protein are essential for survival of cancer cells with wtp53 by suppressing the activity of proapoptotic proteins while enhancing the function of prosurvival proteins in response to the exposure of DNA damage. The main goal of this proposal is to understand the unusual roles of a small GTPase, RhoE, as a novel target gene of p53-dependent DNA damage and to translate our basic understanding of the cell survival function of RhoE into apoptosis for human cancer cells including breast cancer cells. Although the biological role of RhoE in DNA damage response pathway has not yet been defined, our preliminary data demonstrating transactivation of the RhoE gene by p53-dependent DNA damage, its potential role as a key organizer of the actin cytoskeleton, and its exceptional role in DNA damage-induced cell survival are intriguing to us. Accumulating evidence suggest that an aberrant signaling through Rho proteins is closely associated with various steps of tumorigenesis and carcinogenesis. In this application, a combination of biochemical and genetic approaches will be used to (i) delineate the functions of RhoE in p53 dependent cellular outcomes and DNA damage stress response; (ii) Identify and characterize RhoE Interacting partners, which will define a molecular pathway that affects RhoE-mediated cell survival and p53-dependent cell death in response to genotoxic stress; iii) determine if ROCK 1 is an essential upstream regulator for JNK-mediated cell death signaling; and (iv) define the role of RhoE in DNA damage checkpoint signaling and cell survival signaling using in mouse knockout approach.