DEVELOPMENTAL ROLE OF XERODERMA PIGMENTOSUM RELATED GENE

色素性干皮病(XP)和克罗肯综合征(CS)是人类 疾病的特征是对紫外线的敏感性增加和 一系列发育和神经异常。此外，XP 病人表现出患皮肤癌的高易感性。来自患者的细胞 这两种疾病在核苷酸切除修复(NER)中都有缺陷，以及 分成代表不同基因的多个互补组 NER途径。更多的工作已经证明， 其中一些NER基因具有双重作用，作为转录的组成部分 TFIIH因素。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， 尽管这些蛋白质在转录过程中起着直接作用，但 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定。这些 重要的发展过程仍有待确定。 我们建议使用多细胞黏菌盘基网柄菌来 研究XP和CS相关的特定发育和细胞角色 基因。虽然相对简单，但网柄柄菌有许多共同之处 高等真核生物的发育过程。它的易学性使它 导致了它在细胞和细胞上发展的详细画面 分子水平。分子生物学技术，包括那些 同源基因破坏，发展得很好，使构建变得容易 以及对特定突变体的研究。表型可以用以下方法详细研究 广泛的现有技术、探针和抗体。 我们已经鉴定和研究了DictyostelialepE基因，它编码一个 与人UV-DDB(紫外线损伤DNA)同源的预测产物 结合)蛋白，UV-DDB蛋白在某些患者中缺失 XPE。该蛋白编码一个可能的亮氨酸拉链基序。 以及相关联的基本区域。我们已经使RepE基因中断突变， 而且他们在发展方面有一个独特的缺陷。突变的细胞被阻断了 聚集和形成多细胞集合体。有趣的是， 突变细胞可以表达所有测试的早期发育基因和 获得正常聚集细胞的细胞形态。然而，很晚了 发育基因不表达。这些数据表明，RepE 基因是连接早期和晚期的特定发育开关 发展。我们建议旨在分析这一点的具体方面 发育作用包括：1)RepE的发育调节； 2)RepE基因产物的蛋白质和DNA相互作用；以及3) 生化和细胞生物学缺陷导致的表型 Repe突变体。 我们还鉴定了XPB和XPD基因的Dictyostoma同源物 它们在人类身上有各种各样的发育缺陷。我们建议 克隆和破坏这些基因，以便它们的发育作用可以 学习。总体而言，我们的数据表明，网柄苔藓在 阐明XP和CS在发育和细胞中的特殊作用 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.