Cell Cycle Checkpoint in Response to DNA Damage

细胞周期检查点确保从一个复制细胞周期到下一个复制细胞周期的基因组的完整性。在 在基因组发生灾难性损伤的情况下，多细胞真核生物的细胞可以经历凋亡， _合理地将它们从细胞群中消除，并降低遗传繁殖的风险 不稳定的细胞。或者，细胞可以通过经历细胞的短暂停滞来对DNA损伤作出反应 这与它们暴露于DNA损伤剂的生存能力相关。此响应 需要DNA损伤检查点途径;如果受到突变或药物治疗的影响，细胞将进入 “nitosiswith damaged受损DNA and die死亡.裂变酵母是一个非常有价值的系统， 以及表征DNA损伤检查点的组分。事实上，现在已知的许多蛋白质 在哺乳动物细胞中的检查点途径中起作用的基因仅基于其序列被鉴定 与酵母中在遗传和功能上鉴定的蛋白质同源。显然， 利用经典遗传学的力量鉴定酵母中的蛋白质是一种有效和富有成效的方法， 识别并深入了解哺乳动物对应物的功能。本文中描述的实验 该提案将继续研究蛋白激酶Chkl，Chkl是真核生物检查点的关键调节因子。 细胞此外，我们将集中在一个新的裂变酵母蛋白，Mscl。MSC共享结构域 与哺乳动物RbBP 2同源，RbBP 2是一种通过结合肿瘤抑制因子的能力而鉴定的蛋白质 3蛋白Rb和PLU-1，在乳腺癌细胞中上调的基因的产物。Mscl是 因为它可以补偿Chkl功能的丧失。Mscl蛋白似乎在 或染色质的组蛋白修饰，用于基因组稳定性和DNA损伤后的存活。实验 本提案中所描述的目的是剖析Mscl蛋白在裂殖酵母中的作用， 来理解人类同源基因的功能。

Cell cycle checkpoints ensure the integrity of the genome from one replicative cell cycle to the next. In the event of catastrophic damage to the genome, cells of multicellular eukaryotes can undergo apoptosis, _resumably to eliminate them from the cell population and reduce the risk of propagating genetically Jnstable cells. Alternatively, cells may respond to DNA damage by undergoing a transient arrest of the cell =ycle, which correlates with their ability to survive exposure to DNA damaging agents. This response requires the DNA damage checkpoint pathway; if compromised by mutation or drug treatment, cells will enter "nitosiswith damaged DNA and die. The fission yeast has been an extremely valuable system for identifying and characterizing components of the DNA damage checkpoint. Indeed, many proteins that are now known to function in the checkpoint pathway in mammalian cells were identified solely based on their sequence homology to proteins that were identified genetically and functionally in yeast. Thus, it is clear that the identification of proteins in yeast using the power of classical genetics is a valid and productive means of identifying and gaining insight into the function of mammalian counterparts. Experiments described in this proposal will continue to investigate the protein kinase, Chkl, a key regulator of the checkpoint in eukaryotic cells. In addition, we will focus on a novel fission yeast protein, Mscl. Mscl shares structural domain homology with mammalian RbBP2, a protein identified by virtue of its ability to bind the tumor suppressor 3rotein Rb and with PLU-1, the product of a gene that is up regulated in breast cancer cells. Mscl was ',loned because it can compensate for the loss of function Chkl. The Mscl protein appears to be important or histone modifications of chromatin, for genomic stability and for survival after DNA damage. Experiments described in this proposal aim to dissect the role of the Mscl protein in fission yeast, to lay the groundwork for understanding the functions of the human homologues.