CLONING & CHARACTERIZING THE XP VARIANT MUTATOR GENE(S)

描述：细胞来自患有着色性干皮病的个体 (XP)在核苷酸切除修复（NER）的不同方面有缺陷 除了XP变异（XP-V）个体外， 正常NER。 对于XP-V最普遍接受的假设是， 由于聚合酶相关基因的缺陷， 病变旁路。 首席研究员希望克隆XP-V基因 以便更好地理解这种缺陷的分子基础。 证据 与遗传学的机制有关， 在干皮病中发现的日光诱发皮肤癌的易感性 色素变性（XP-V）患者，这些患者出现以下临床特征 经典XP患者仍具有正常的切除修复。 他们的细胞 在复制紫外线损伤的DNA时异常缓慢，并且对 紫外线诱导的突变 数据显示，这种极端 超变性反映了一种有缺陷的、容易出错的复制复合体， 产生了异常的紫外线诱导突变谱。 不仅 在完整的细胞中复制异常容易出错，但这也是真的 用无细胞提取物体外复制辐照过的模板 来自XP-V细胞。 它们代表了唯一已知的人类细胞的例子， 不是由有缺陷的DNA引起的有缺陷的易错复制复合体 修复. 因此，他们提供了一个机会，调查机制， 正常细胞用来确保高保真的DNA复制。 提出要 同时使用两种方法来克隆负责 XP-V细胞的异常特征，然后表征该基因 鉴定及其蛋白质产物。

DESCRIPTION: Cells from individuals with the disease Xeroderma pigmentosum (XP) are defective in different facets of nucleotide excision repair (NER) with the exception of XP-variant (XP-V) individuals, which appear to have normal NER. The most commonly accepted hypothesis for XP-V is that it is due to a defect in a polymerase-related gene that leads to error-prone bypass of lesions. The principal investigator wishes to clone the XP-V gene in order to better understand the molecular basis of this defect. Evidence is presented bearing on the mechanism(s) responsible for the genetic predisposition to sunlight-induced skin cancer found in xeroderma pigmentosum variant (XP-V) patients, who develop clinical features of classical XP patients yet have normal excision repair. Their cells are abnormally slow in replicating UV-damaged DNA and are extremely sensitive to UV-induced mutations. Data has been obtained that suggest that this extreme hypermutability reflects a defective, error-prone replication complex that yields an abnormal spectrum of UV-induced mutations. Not only is replication in the intact cells abnormally error-prone but this is also true for in vitro replication of an irradiated template by cell-free extracts from XP-V cells. They represent the only known example of human cells with a defective error-prone replication complex not resulting from defective DNA repair. Thus, they offer an opportunity to investigate the mechanisms normal cells use to insure high-fidelity DNA replication. It is proposed to use two approaches simultaneously to clone the gene(s) responsible for the abnormal characteristics of XP-V cells and then to characterize the gene identified and its protein product.