TULANE CANCER GENETICS COBRE: ATR KINASE AND UV-INDUCED CELL CYCLE CHECKPOINTS

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。细胞周期检查点是真核细胞对DNA损伤剂如电离辐射（IR）和紫外线辐射（UV）做出最佳反应的机制之一。这些细胞周期进程的控制者可能增强了遗传稳定性并限制了生物体中的肿瘤发生。表征这些信号通路中的生化步骤将有助于提高我们对以下方面的理解：1)正常细胞周期控制；2) DNA损伤后细胞转化的机制。虽然红外诱导的细胞周期检查点已被广泛研究，但对紫外线诱导的细胞周期阻滞知之甚少。我们的长期目标是阐明控制紫外线诱导的细胞周期检查点的信号转导途径。我们的初步观察表明，ATM-RAD3相关激酶ATR是紫外线诱导的s期和G2/M检查点所必需的。ATR是磷脂酰肌醇激酶相关蛋白家族的一员，对于DNA损伤或复制阻滞的存在和激活细胞周期检查点至关重要。由于大多数DNA损伤诱导的信号通路由调节细胞周期进程的激酶依赖性信号级联组成，我们推断ATR通过其下游靶点的磷酸化在紫外线诱导的细胞周期检查点的激活中起核心作用。我们提出了三个具体的目的来剖析ATR在紫外线诱导的周期检查点中的作用。在Specific Aim 1中，我们将研究BRCA1、NBS1和SMC1是否参与ATR依赖性s期阻滞，以及ATR是否磷酸化这些蛋白以促进阻滞。在Specific Aim 2中，我们将研究ATR激酶和p38 MAP激酶在紫外线诱导的G2阻滞中的生化联系。在具体的Aim 3中，我们将研究RAD 17是否是一种DNA损伤传感器，用于招募ATR来调节检查点。这些研究将为ATR激酶的作用和机制提供新的见解，并在此过程中阐明环境DNA损伤后细胞周期控制的机制。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Cell cycle checkpoints are among the mechanisms developed by eukaryotic cells to optimally respond to DNA damage agents, such as ionizing radiation (IR) and ultraviolet radiation (UV). These controllers of cell cycle progression presumably enhance genetic stability and limit tumorigenesis in the organism. Characterization of the biochemical steps in these signaling pathways will help improve our understanding of: 1) normal cell cycle control; and 2) mechanisms of cellular transformation following DNA damage. While IR-induced cell cycle checkpoints have been extensively studied, less is known about UV-induced cell cycle arrest. Our long term goal is to elucidate the signal transduction pathways that control UV-induced cell cycle checkpoints. Our preliminary observations suggest that the ATM-RAD3 related kinase, ATR, is required for UV-induced S-phase and G2/M checkpoints. ATR is a member of the phosphatidylinositol kinase related protein family that is essential for signaling the presence of DNA damage or replication blocks and activating cell cycle checkpoints. Since most of the DNA damage-induced signaling pathways consist of kinase-dependent signaling cascades that regulate cell cycle progression, we reason that ATR plays a central role in activation of UV-induced cell cycle checkpoints through phosphorylation of its downstream targets. We propose three specific aims to dissect the role of ATR in UV-induced cycle checkpoints. In Specific Aim 1, we will investigate whether BRCA1, NBS1 and SMC1 are involved in ATR-dependent S-phase arrest, and whether ATR phosphorylates these proteins to facilitate the arrest. In Specific Aim 2, we will investigate the biochemical linkage of ATR kinase and p38 MAP kinase in UV-induced G2 arrest. In specific Aim 3, we will investigate whether RAD 17 is a DNA damage sensor for recruiting ATR to regulate the checkpoints. These studies will provide novel insights into the roles and mechanisms of the ATR kinase and, in the process, should shed light on mechanisms involved in cell cycle control after environmental DNA damage.