EXCISION REPAIR OF UV RADIATION-INDUCED DNA DAMAGE

描述：紫外光照射细胞的生物学效应 包括死亡、突变和肿瘤转化。DNA是 紫外线照射的生物相关目标，导致 环丁烷嘧啶二聚体(CPDS)和(6-4)的形成 摄影产品(6-4PPS)。CPDS和6-4 PPS已被证明具有细胞毒性， 在细胞和动物模型系统中具有诱变性和致癌性，并且很容易 暴露在阳光下后在人体皮肤细胞中形成。皮肤癌， 在人类中最常见的癌症，主要与 长期暴露在太阳辐射下。大多数的基础和 皮肤鳞状细胞癌包含P53肿瘤突变 抑制基因，是由CPDS和6-4 PPS引起的类型。一个 对慢性阻塞性肺疾病修复的成分和生化的认识 真核生物中的6-4PPS应该为机制提供重要的见解 紫外线致癌的证据。裂解酵母，裂殖酵母庞贝提供 一种诱人的生物化学和遗传真核DNA修复模型系统 其特征包括丰富的酶细胞来源 纯化和鉴定，相对简单的遗传 可分离性，以及一种可切割的庞贝链球菌内切酶的特征 特别识别CPD和6-4 PPS，并直接进行5‘切开 在这些紫外线照相产品的位置。我们有生物学的和遗传的 有证据表明，这种酶，S.pombe DNA内切酶(SPDE)，代表 我们拥有的另一种DNA切除修复系统的第一步 被称为SPDE依赖的DNA修复(SDR)途径。现在看来， 类似SDR的途径也存在于其他生物体中。的目标是 拟议的研究将用显著的 重点放在SPDE上。生物化学与分子生物学的结合 将采取办法提供关于特别提款权和特别提款权的直接信息。 路径。主要目标将是(1)完成提纯和 对SPDE进行详细的酶学鉴定；(2)鉴定和鉴定 鉴定编码SPDE的基因；(3)鉴定和鉴定其他 SDR途径的组成部分；以及(4)筛选候选 生物体，包括人类，进行类似SPDE的活动来确定 SDR途径的物种分布。在这些文件中获得的信息 研究应该大大增加我们对真核细胞的了解。 逆转致癌紫外线照相产品的机械。

DESCRIPTION: The biological effects of UV light irradiation of cells include death, mutation and neoplastic transformation. DNA is the biologically relevant target of UV light exposure, resulting in the formation of primarily cyclobutane pyrimidine dimers (CPDs) and (6-4) photoproducts (6-4 PPs). CPDs and 6-4 PPs have been shown to be cytotoxic, mutagenic, and carcinogenic in cell and animal model systems and are readily formed in human skin cells following exposure to sunlight. Skin cancer, the most frequently occurring cancer in humans, is primarily associated with chronic exposure to solar radiation. The majority of both basal and squamous cell carcinomas of the skin contain mutations in the p53 tumor suppressor gene and are of the type caused by CPDs and 6-4 PPs. An understanding of the components and biochemistry of the repair of CPDs and 6-4 PPS in eukaryotes should provide important insights into the mechanisms of UV carcinogenesis. The fission yeast, Schizosaccharomyces pombe provides an attractive biochemical and genetic eukaryotic DNA repair model system with features that include an abundant source of cells for enzyme purification and characterization, relatively straightforward genetic dissectability, and the characterizing a S. pombe endonuclease that specifically recognizes both CPDs and 6-4 PPs and makes direct 5'incisions at the sites of these UV photoproducts. We have biological and genetic evidence that this enzyme, S. pombe DNA endonuclease (SPDE), represents the initial step of an alternative DNA excision repair system which we have termed the SPDE-dependent DNA repair (SDR) pathway. It now appears that SDR-like pathways are also present in other organisms. The goal of the proposed research will be to characterize the SDR pathway with a significant focus on SPDE. A combination of biochemical and molecular biological approaches will be taken to provide direct information on SPDE and the SDR pathway. The major objectives will be to (1) complete the purification and conduct a detailed enzymological characterization of SPDE; (2) identify and characterize the gene encoding SPDE; (3) identify and characterize other components of the SDR pathway; and (4) screen a selection of candidate organisms, including humans, for a SPDE-like activity to determine the species distribution of the SDR pathway. The information obtained in these studies should greatly increase our understanding of the eukaryotic cellular machinery that reverses carcinogenic UV photoproducts.