DOMAIN ORGANIZATION OF DNA REPAIR IN HUMAN CELLS

通过核苷酸切除修复(NER)，生物体移除受损的 核苷酸，如紫外线诱导的环丁烷嘧啶二聚体。 NER有两个子途径：全球基因组修复和转录 耦合修复(TCR)。有证据表明，TCR更有效率， 很早就发生了。显然，RNA聚合酶停留在受损的DNA和 转录阻断损伤的转录链的表达 基因被移除了。虽然关于GGR和TCR的基因控制已知很多， 人们对它们的细胞定位知之甚少。调查人员将 5-碘脱氧尿苷(IDU)标记人成纤维细胞修复补片 GGR(着色性干皮病)或TCR(Cockayne病)存在缺陷 综合征)，以确定DNA合成的焦点位置。脉冲标记法 将进行实验，以确定和列举早期和晚期的焦点 修复合成。使用不同的胸苷类似物，研究人员预计 绘制修复的早期和晚期区域并将它们与染色体联系起来 基因密度高和低的区域。他们还将分析亲属 修复灶与间期核的分布和共定位 GGR和TCR的蛋白质诊断。预计这些细胞学上的 方法将补充对NER和NER的基本生化理解 为人类细胞中GGR和TCR的调控提供新的见解。

Through nucleotide excision repair (NER), an organism removes the damaged nucleotides e.g. UV-induced cyclobutane pyrimidine dimers from its genome. There are two sub-pathways of NER; global genome repair (GGR) and transcription coupled repair (TCR). There is some evidence that TCR is more efficient and occurs early. Apparently, RNA polymerase stops at the damaged DNA and the transcription blocking lesion from the transcribed strands of the expressed gene is removed. While much is known about the genetic control of GGR and TCR, very little is known about their cellular localization. The investigators will use 5-iododeoxyuridine (IdU) labeling of repair patches in human fibroblasts with deficiencies either in GGR (Xeroderma Pigmentosa-C) or in TCR (Cockayne's syndrome) to determine the focal sites of DNA synthesis. Pulse-labeling experiments will be done to identify and enumerate the early and late foci of repair synthesis. Using different thymidine analogs, the investigators expect to map the early and late domains of repair and to relate these to chromosomal regions of high and low gene density. They will also analyze the relative distribution and co-localization in interphase nuclei of repair foci and proteins diagnostic of GGR and TCR. It is anticipated that these cytological approaches will complement the basic biochemical understanding of NER and provide new insights into the regulation of GGR and TCR in human cells.