DEVELOPMENTAL ROLE OF XERODERMA PIGMENTOSUM RELATED GENE

着色性干皮病（XP）和Crockayne综合征（CS）是人类 特征在于对UV光的敏感性增加的疾病， 一系列的发育和神经异常 此外，XP 患者显示出患皮肤癌的高倾向性。 细胞中 在核苷酸切除修复（NER）中有缺陷，并且 属于多个互补组，代表不同的基因， 的路径。 进一步的工作表明， 这些NER基因中的一些作为转录的组分具有双重作用， 因子TFIIH。 这些基因产物参与转录 开始解释XP突变的多效性效应。 然而，在这方面， 尽管这些蛋白质在转录中起直接作用， 与XP相关的异常通常是有限的。 这表明 这些蛋白质可能参与特定的发育决策。 这些 重要的发展进程仍有待确定。 我们建议使用多细胞黏菌，盘基网柄霉， 研究XP和CS相关的特定发育和细胞作用 基因. 虽然相对简单，但网骨藻具有许多 高等真核生物的发育过程。 它的易用性， 导致了它在细胞和 分子水平。 分子生物学技术，包括用于 同源基因破坏，是非常发达的，允许容易的构建 研究特定的突变体。 表型可以使用 广泛的现有技术、探针和抗体。 我们已经鉴定并研究了Dictyosterebellum repE基因，该基因编码一种 与人UV-DDB（UV损伤的DNA）同源的预测产物 结合）蛋白，UV-DDB蛋白在一些患有 XPE 预测的repE蛋白编码一个假定的亮氨酸拉链基序 和相关的碱性区域。 我们已经制造了repE基因破坏突变体， 它们在发育过程中有一个独特的缺陷。 变异细胞被阻断了 在聚集和形成多细胞集合体中。 有趣的是， 突变细胞可以表达所有测试的早期发育基因， 获得正常聚集细胞的细胞形态。 然而，晚 发育基因不表达。 这些数据表明， 基因作为一种特殊的发育开关， 发展 我们提出的目的是分析这方面的具体方面， 发育作用包括：1）repE的发育调节作用; 2)repE基因产物的蛋白质和DNA相互作用;以及3） 生物化学和细胞生物学缺陷负责的表型 repE突变体 我们还鉴定了XPB和XPD基因的网骨藻同源物 在人类身上有很多发育缺陷。 我们建议 克隆并破坏这些基因， 研究了 总的来说，我们的数据表明，网骨藻是有用的， 阐明XP和CS的特定发育和细胞作用 基因.

Xeroderma pigmentosum (XP) and Crockayne's syndrome (CS) are human disorders that are characterized by increased sensitivity to UV light and a range of developmental and neurological abnormalities. In addition, XP patients show a high predisposition to skin cancer. Cells from patients with both diseases are defective in nucleotide excision repair (NER), and fall into multiple complementation groups that represent different genes of the NER pathway. Additional work has demonstrated that the products of some of these NER genes have dual roles as components of the transcription factor TFIIH. The involvement of these gene products in transcription begins to explain the pleiotropic effects of the XP mutations. However, even though these proteins play a direct role in transcription, the abnormalities associated with XP are generally limited. This suggests that these proteins may be involved in specific developmental decisions. These important developmental processes remain to be identified. We propose to use the multicellular slime mold, Dictyostelium discoideum to study the specific developmental and cellular roles of XP and CS related genes. Although relatively simple, Dictyostelium shares many of the developmental processes of higher eucaryotes. Its ease of study has resulted in a detailed picture of its development at both the cellular and molecular levels. Molecular biology techniques, including those for homologous gene disruption, are well developed allowing facile construction and study of specific mutants. Phenotypes can be studied in detail using a wide range of existing techniques, probes and antibodies. We have identified and studied the Dictyostelium repE gene which encodes a predicted product that is homologous to the human UV-DDB (UV-damaged DNA binding) protein, The UV-DDB protein is absent from some patients with XPE. The predicted repE protein encodes a putative leucine-zipper motif and an associated basic region. We have made repE gene disruption mutants, and they have a unique defect in development. The mutant cells are blocked in aggregation and formation of multicellular assemblies. Interestingly, the mutant cells can express all the early developmental genes tested and acquire the cellular morphology of normal aggregating cells. However, late developmental genes are not expressed. These data suggest that the repE gene acts as a specific developmental switch linking early and late development. We propose aims to analyze specific aspects of this developmental role including; 1) the developmental regulation of repE; 2) the protein and DNA interactions of the repE gene product; and 3) the biochemical and cell biological defects responsible for the phenotype of the repE mutants. We have also identified the Dictyostelium homologs of the XPB and XPD genes which have a variety of developmental defects in humans. We propose to clone and disrupt these genes so that their developmental roles can be studied. Overall, our data indicate that Dictyostelium is useful in elucidating the specific developmental and cellular roles of XP and CS genes.