POLYCOMB-GROUP GENES AND GENE REGULATION

果蝇zeste [E（z）]基因座的增强子 在发育过程中基因抑制的多个例子中。 第一 确定为zeste 1-白色（z-w）的主要功能增益调节剂 在相互作用中，突变的E（z）等位基因也产生同源异型转化。 E（z）+活性的降低导致z-w抑制， 的片段身份基因的相互作用和异位表达 双胸基因复合体。 后一种效应定义了E（z） 作为Polycomb基因组的一员。 母亲和 合子产生的E（z）+活性是正确调节 片段身份基因在胚胎和成虫发育过程中。 完成 合子产生E（z）活性的缺乏导致细胞的阻塞 幼虫成神经细胞增殖和染色体断裂 organization. 因此，似乎E（z）+的还原干扰了 许多基因抑制的例子，它的完全缺失阻止了 细胞增殖并破坏染色体组织。 因此，我们认为， 通过对E（z）蛋白活性的分子和生化分析， 基因调控和更高级的染色质组织之间的联系可能是 阐明。 这项工作的长期目标是了解 E（z）产物的分子机制，以及其他 多梳组基因，执行其遗传定义的功能。 的 这项建议的具体目标是采用多方面的办法， 包括遗传学、分子学、免疫学和生物化学工具，以（1） 确定E（z）蛋白的亚细胞和细胞内定位 整个生物体，（2）阐明其分子机制， 抑制转录，和（3）剖析E（z）的功能结构域， 蛋白 所采取的方法包括（1）使用特异性抗体 对于E（z）蛋白，以确定其定位，（2）使用这些相同的 抗体，以检查潜在的体外和体内相互作用， E（z）蛋白，两者都具有已被鉴定的调控DNA序列， 作为E（z）活性的靶标，以及与其他基因的产物， 在遗传学上已经显示出与E（z）相互作用，以及（3）DNA序列 现有突变E（z）等位基因的分析，以及体外构建 基因的改变形式，然后将在体外表达， 引入果蝇生殖系，并在体外和体内进行测定。 体内活性。 基因表达的失调已经被 与许多疾病有关，包括各种癌症。 从长远 更好地理解基因调控的机制 而高阶染色体组织的潜在作用将是 这对理解和治疗这些疾病至关重要。

The Enhancer of zeste [E(z)] locus of Drosophila melanogaster is implicated in multiple examples of gene repression during development. First identified as dominant gain-of-function modifiers of the zeste1-white (z-w) interaction, mutant E(z) alleles also produce homeotic transformations. Reduction of E(z)+ activity leads to both suppression of the z-w interaction and ectopic expression of segment identity genes of the Antennapedia and bithorax gene complexes. This latter effect defines E(z) as a member of the Polycomb-group of genes. Both maternally and zygotically produced E(z)+ activity is required to correctly regulate the segment identity genes during embryonic and imaginal development. Complete lack of zygotically produced E(z) activity results in blockage of cell proliferation in larval neuroblasts, and disruption of chromosome organization. Thus, it seems that reduction of E(z)+ interferes with multiple examples of gene repression, and that its complete absence blocks cell proliferation and disrupts chromosome organization. Therefore, through molecular and biochemical analysis of E(z) protein activity, a link between gene regulation and higher order chromatin organization may be elucidated. The long term goal of this work is to gain an understanding of the molecular mechanisms by which the E(z) product, and those of other Polycomb-group genes, carry out their genetically defined functions. The specific aims of this proposal are to utilize a multifaceted approach including genetic, molecular, immunological and biochemical tools to (1) determine the localization of the E(z) protein, both subcellular and within the whole organism, (2) elucidate the molecular mechanism(s) by which it represses transcription, and (3) dissect the functional domains of the E(z) protein. The approaches to be taken include (1) use of antibodies specific for the E(z) protein to determine its localization, (2) use of these same antibodies to examine potential in vitro and in vivo interactions of the E(z) protein both with regulatory DNA sequences that have been identified as targets for E(z) activity, and with the products of other genes that have been genetically shown to interact with E(z), and (3) DNA sequence analysis of existing mutant E(z) alleles, and in vitro construction of altered forms of the gene, which will then be both expressed in vitro and introduced into the Drosophila germ line and assayed for in vitro and in vivo activities, respectively. Misregulation of gene expression has been implicated in a number of diseases, including various cancers. In the long term, a better understanding of the mechanisms by which genes are regulated and the potential role of higher order chromosome organization will be crucial to understanding and treating such diseases.