POLYCOMB-GROUP GENES AND GENE REGULATION

多细胞生物的发展需要特定的命运 被分配给细胞，这些细胞“记住”这些指令 通过许多周期的细胞分裂。一个有据可查的例子 涉及果蝇触角的转录调控 (Ant-C)和双胸腺(BX-C)基因复合体。最初的模式是 Ant-C和BX-C的表达受转录因子控制 是由分段基因编码的。然而，在这些之后不久， 模式被建立，分割基因的产物是 降级了。ANT-C和BX-C转录活性的维持和 然后，镇压就成了各自的责任 三胸蛋白(Trx-G)和多梳蛋白(Pc-G)。的同系物 Trx-G和Pc-G基因已在多种生物体中被发现 一些基因的突变与肿瘤的发生有关。我们的长期合作 目的是了解Pc-G和Pc-G的分子机制 Trx-G维持靶基因的转录状态。这个 本提案中描述的实验旨在更好地定义 ZEST增强子Pc-G蛋白的分子活性[E(Z)].在……里面 除了其在Pc-G介导的抑制中的作用外，E(Z)还可能 参与Trx-G介导的激活。E(Z)蛋白已被证明 与另外两种Pc-G蛋白相互作用，以及另一种共享的蛋白质 与作为组成部分的人类蛋白质的广泛序列相似性 压抑情结。初步证据表明，几种TRX- G蛋白也是潜在的E(Z)结合伙伴。所有这些都是 将使用酵母双杂交、体外结合、 和免疫共沉淀试验。它们在体内的功能 特定的蛋白质-蛋白质关系将通过基因 携带特异性E(Z)点突变的转基因分析 打乱了各自的互动。E(Z)的体内相关性 这些蛋白质和其他蛋白质也将通过表征 胚胎提取物中含有天然E(Z)的络合物。

The development of multicellular organisms requires that specific fates be assigned to cells and that cells "memorize" these instructions through many cycles of cell division. A well documented example involves the transcriptional regulation of the Drosophila Antennapedia (ANT-C) and bithorax (BX-C) gene complexes. The initial patterns of ANT-C and BX-C expression are controlled by transcription factors that are encoded by the segmentation genes. However, shortly after these patterns are established, the products of the segmentation genes are degraded. Maintenance of ANT-C and BX-C transcriptional activity and repression then becomes the respective responsibilities of the trithorax-group (trx-G) and Polycomb-group (Pc-G) proteins. Homologs of trx-G and Pc-G genes have been identified in a wide variety of organisms and mutations in some are associated with oncogenesis. Our long-term goal is to understand the molecular mechanisms by which the Pc-G and trx-G maintain the transcriptional states of target genes. The experiments described in this proposal are designed to better define the molecular activities of one Pc-G protein, Enhancer of zeste [E(z)]. In addition to its role in Pc-G mediated repression, E(z) may also participate in trx-G-mediated activation. E(z) protein has been shown to interact two other Pc-G proteins, and another protein that shares extensive sequence similarity with a human protein that is a component of repression complexes. Preliminary evidence suggests that several trx- G proteins are also potential E(z) binding partners. All of these interactions will be analyzed using yeast two-hybrid, in vitro binding, and co-immunoprecipitation assays. The in vivo functions of these specific protein-protein relationships will be defined through genetic analysis of E(z) transgenes bearing point mutations that specifically disrupt the respective interactions. The in vivo associations of E(z) with these and other proteins also will be examined by characterizing native E(z)-containing complexes from embryo extracts.