Genome maintenance by the mouse Hus1 checkpoint gene

描述（申请人提供）：小鼠HUS1突变点基因的基因组维持 癌症的产生是由于生长调节基因突变的连续积累。因此，保护基因组完整性在肿瘤抑制中起着关键作用。基因组的维持部分是通过细胞周期检查点来实现的，细胞周期检查点通过调节细胞周期进程、凋亡和DNA修复来防止基因组损伤的积累。在哺乳动物中，蛋白质Atr、Hus1和Chk1组成了一个检查点通路，该通路响应特定的DNA损伤以及DNA复制停滞。该提案中描述的研究的长期目标是确定这种依赖于Hus1的检查点途径如何维持基因组稳定性并有助于正常发育和肿瘤抑制。在本提案的目的之一，我们将确定在原代小鼠细胞中DNA损伤信号和细胞周期检查点对Husl的需求。在目标二中，我们将确定成年小鼠中的Husl失活是否促进肿瘤发生并损害组织特异性DNA损伤反应。这些目标将使用一种新的系统来实现，该系统用于调节Hus1的失活，该系统绕过了小鼠胚胎发育期间对这一重要途径的需求。虽然Hus1依赖性检查点机制的完全失活导致严重的基因组不稳定性，但其他证据表明，该途径的部分缺陷可能导致发育缺陷并促进肿瘤形成。在第三个目标中，我们将利用一种新的亚型Hus1等位基因，该等位基因表达的Hus1水平大大降低，以测试Hus 1依赖性检查点通路的部分损伤是否会导致培养细胞和小鼠的基因组不稳定性和遗传毒性应激反应的改变。总之，拟议的研究将揭示一个关键的哺乳动物检查点途径如何在整个细胞周期中运作，并将定义这种检查点机制在肿瘤抑制和体内基因组维持中的作用。

DESCRIPTION (provided by applicant): GENOME MAINTENANCE BY THE MOUSE HUS1 CHECKPOINT GENE Cancers arise due to the sequential accumulation of mutations in growth regulatory genes. The safeguarding of genomic integrity therefore plays a critical role in tumor suppression. Genome maintenance is achieved in part through cell cycle checkpoints, which prevent the accumulation of genome damage by regulating cell cycle progression, apoptosis, and DNA repair. In mammals, the proteins Atr, Hus1, and Chk1 comprise a checkpoint pathway that responds to specific DNA lesions as well as DNA replication arrest. The long-term goal of the research described in this proposal is to determine how this Hus1-dependent checkpoint pathway maintains genomic stability and contributes to normal development and tumor suppression. In aim one of this proposal, we will identify requirements for Husl in DNA damage signaling and cell cycle checkpoints in primary mouse cells. In aim two, we will establish whether Husl inactivation in adult mice promotes tumorigenesis and impairs tissue-specific DNA damage responses. These objectives will be accomplished using a new system for the regulated inactivation of Hus1 that bypasses the requirement for this essential pathway during murine embryonic development. While complete inactivation of the Hus1-dependent checkpoint mechanism leads to severe genomic instability, additional evidence suggests that a partial deficiency in this pathway can cause developmental defects and promote tumor formation. In aim three, we will utilize a novel hypomorphic Hus1 allele that expresses greatly reduced levels of Hus1 to test whether partial impairment of the Hus 1-dependent checkpoint pathway causes genomic instability and altered genotoxic stress responses in cultured cells and mice. Together, the proposed studies will reveal how a key mammalian checkpoint pathway operates throughout the cell cycle and additionally will define the roles of this checkpoint mechanism in tumor suppression and in vivo genome maintenance.