SNRNP MEDIATORS OF VERTEBRATE GENE EXPRESSION

脊椎动物中的10种小核核糖核蛋白 核质有助于前信使RNA的成熟，如 拼接或3‘端成形机械的部件。相比之下， 大约200个小核仁RNP(SnoRNP)直接 切割和特定的核苷酸修饰，将前- 核糖体RNA(RRNA)转化为成熟的18S、5.8S和28S rRNA。其他内容 SNRNP(定位未知)直接修饰其他 单链RNA。它们的功能、作用机制和生物发生 SnRNPs和snoRNPs将主要使用Hela在体外进行研究 萃取物和非洲爪哇卵母细胞。针对U1、U2、U4/U6和U5 snRNP 在主要的剪接体中，可光激活的核苷酸将是 被引入到小分子RNA中，以分析它们在 拼接。修饰核苷酸在这些单链RNA中的精确功能 将被鉴定并研究它们的生物起源，特别是通过 确定有多少是由其他SnRNA指南指导的。对于新的 特征性的，低丰度AT-AC剪接体，既有其显著的 与主要剪接体的差异及其原因 在进化中的维持将被探索。AT-AC剪接体组装将 被解剖以询问为什么U11/U12 SnRNP作为一个复合体 发现AT-AC特定的外显子增强子是否存在。对智能网的分析 体内Pre-mRNA群体将确定AT-AC内含子是否被移除 是限速的。两种选择性剪接的必要性(AT-AC 而不是去除主要内含子) 将调查果蝇的发育及其调控。这个 形成组蛋白mRNAs 3‘末端的机械将被解剖 通过对蛋白质(S)的表征，可以沿着 单链前信使核糖核酸和通过研究是否切割 因子与聚腺苷酸化所需的因子相同。SnoRNPs 直接rRNA2‘-O-甲基化将被提纯以表征 甲基酶和使用snoRNA-rRNA的体外甲基化反应 嵌合体将被开发出来。核苷酸类似干扰作图 (NIAM)将被用来确定重要的RNA决定因素。 引导基因甲基化的snoRNP之间可能的协调 将对28岁的特定社区进行调查。来说明为什么所有 SnoRNA宿主基因是5‘顶端基因，是5’顶端序列的核心角色 这可能有助于释放内含子编码的snoRNAs 被追寻。SNRNPs和SnRNPs的生物发生和功能的扰动 SnoRNPs是某些人类疾病的决定因素，可能还会导致衰老。

Ten small nuclear ribonucleoproteins (snRNPs) in the vertebrate nucleoplasm contribute to the maturation of pre-messenger RNAs as components of the splicing or 3'-end formation machinery. In contrast, approximately two hundred small nucleolar RNPs (snoRNPs) direct cleavages and specific nucleotide modifications, converting the pre- ribosomal RNA (rRNA) into mature 18S, 5.8S and 28S rRNAs. Additional snRNPs (of unknown localization) direct the modification of other snRNAs. The functions, mechanisms of action and biogenesis of these snRNPs and snoRNPs will be investigated using primarily Hela in vitro extracts and the Xenopus oocyte. For the U1, U2, U4/U6 and U5 snRNPs of the major spliceosome, photoactivatable nucleotides will be introduced into the snRNAs to analyze their molecular contacts during splicing. The precise functions of modified nucleotides in these snRNAs will be identified and their biogenesis investigated, particularly by establishing how many are directed by other snRNA guides. For the newly characterized, low-abundance AT-AC spliceosome, both its salient differences compared to the major spliceosome and why it has been maintained in evolution will be probed. AT-AC spliceosome assembly will be dissected to ask why the U11/U12 snRNP acts as a complex and to discover whether AT-AC specific exonic enhancers exist. Analyses of in vivo pre-mRNA populations will establish whether AT-AC intron removal is rate-limiting. Both the necessity for alternative splicing (AT-AC versus major intron removal) of the prospero gene transcript during Drosophila development and its regulation will be investigated. The machinery that fashions the 3' ends of histone mRNAs will be dissected by characterizing the protein(s) that allow measurement along the single-stranded pre-mRNA and by investigating whether the cleavage factor is the same as that required for polyadenylation. SnoRNPs that direct rRNA 2'-O-methylation will be purified to characterize the methylase and an in vitro methylation reaction employing snoRNA-rRNA chimeras will be developed. Nucleotide analog interference mapping (NIAM) will be used to identify the important RNA determinants. Possible coordination between snoRNPs that guide methylation of a particular neighborhood of 28S will be probed. To illuminate why all snoRNA host genes are 5' TOP genes, a nuclear role for 5' TOP sequences that might contribute to the release of intron-encoded snoRNAs will be sought. Perturbations in the biogenesis and functioning of snRNPs and snoRNPs are determinants in certain human diseases and perhaps aging.