RNA PROCESSING AND NUCLEAR RIBONUCLEOPROTEIN

对真核基因的作用机制及其调控的认识 表达对于更大的调控目标至关重要 这些过程是在患病的细胞状态下进行的。可操作的控制 在转录后核阶段的前信使RNA是 正在研究中。在此期间，前信使核糖核酸转录本被打包 与hnRNP和SnRNP组成的核糖核蛋白复合体 它成为剪接和聚腺苷酸化反应的底物； 然后它们作为成熟的mRNAs从细胞核输出，用于 在细胞质中的翻译。A/B hnRNP蛋白与 在整个过程中，这些文本都与 RNA共转录，它们一直伴随着它，直到它转变之后 核孔。有许多有启发性的证据表明，A/B HnRNP蛋白可能在RNA包装中发挥重要作用， 加工和出口，尽管体内的确凿证据已经证明 很难获得。在中国建立了一个非常有利的制度 果蝇黑腹果蝇将允许联合 遗传学/细胞学/超微结构方法研究卵巢癌 这些蛋白质在生物体中的功能。最近使用 获得在两个主要A/B hnRNP都有零突变的果蝇 蛋白质基因，(当胚胎晚期死亡时 纯合子)，将进行RNA转录、加工的检测 当蛋白质水平降到所需的 正常功能。这些分析将是超微结构的(米勒染色质 传播)、细胞学和表型。苍蝇将被确定为 有一个有条件表达的hnRNA蛋白基因，所以这些检测 可以在感兴趣的其他组织和发育阶段进行。 在关于这些蛋白质的大量可用生化数据的指导下， 表达特定突变蛋白的基因将被引入野生环境 苍蝇。在这种背景下，他们将被检测是否有可能 对RNA加工和出口的跨显性效应及其 与多烯上转录位点结合的特定模式 染色体。然后它们将被杂交到双重突变苍蝇中 并检测它们拯救生存能力的能力。这两者结合在一起 将一种强大的体内试验方法用于特定蛋白质的作用 在RNA识别、处理和出口方面的领域，将提供 A/B hnRNP蛋白在生活中功能的关键测试 有机体。

An understanding of the mechanisms and controls of eukaryotic gene expression is of critical importance to the larger goal of regulating these processess in diseased cell states. The controls that are operative on pre-messenger RNA at the post-transcriptional nuclear stage are being studied. During this period, pre-mRNA transcripts are packaged with hnRNP and snRNP components into a ribonucleoprotein complex which becomes the substrate for splicing and polyadenylation reactions; they are then exported from the nucleus as mature mRNAs for translation in the cytoplasm. The A/B hnRNP proteins are associated with these transcripts throughout the entire process--they bind to the RNA co-transcriptionally and they remain with it until after it transits the nuclear pore. There is much suggestive evidence that the A/B hnRNP proteins may play important roles in RNA packaging, processing and export, although definitive in vivo evidence has proven difficult to obtain. A very favorable system has been established in Drosophila melanogaster which will allow a combined genetic/cytological/ultrastructural approach to investigation of the function of these proteins in a living organism. Using recently obtained flies that have null mutations in both of the major A/B hnRNP protein genes, (and which are late embryonic lethals when homozygous), assays will be done of RNA transcription, processing and mRNA export as the protein levels fall below that required for normal function. These assays will be ultrastructural (Miller chromatin spreading), cytological and phenotypic. Flies will be established that have a conditionally expressed hnRNA protein gene so that these assays can be done in other tissues and developmental stages of interest. Guided by a wealth of available biochemical data on these proteins, genes expressing specific mutant proteins will be introduced into wild flies. In this background, they will be assayed for possible transdominant effects on RNA processing and export and for their specific patterns of binding to sites of transcription on polytene chromosomes. They will then be crossed into the double mutant flies and assayed for their ability to rescue viability. This combined approach will be a powerful in vivo test of the role of specific protein domains in RNA recognition, processing and export and will provide a critical test of the function of A/B hnRNP proteins in a living organism.