Small RNP Mediators of Gene Expression

描述（由申请人提供）：信使RNA生物发生的核步骤由小核核糖核蛋白（snRNP）协调，snRNP是两个剪接体和组蛋白mRNA 3 '端加工机制作用的核心参与者。其他类型的snRNP引导核仁中的核糖体RNA（snoRNP）或卡哈尔体中的剪接体snRNA（scaRNP）的核苷酸修饰。一类新的微小RNP，microRNP，在细胞核中经历早期的生物合成步骤，但在细胞质中发挥作用，以调节mRNA靶点的翻译。snRNP，scaRNP和microRNP的作用和生物发生的机制将进行研究，重点是使用哺乳动物细胞，非洲爪蟾卵母细胞，以及果蝇和酵母细胞的潜在分子相互作用。这些小RNP及其成分如何促进基因表达步骤的耦合是一个中心焦点，包括用于执行各种过程的共同组件之间的协同作用。对于盒C/D scaRNP，我们将阐明负责其Cajal体定位的信号和因子，这使得它们能够对剪接体snRNA起作用。我们将研究选择性剪接，包括选择使用主要（U2型）或次要（U12型）剪接体在果蝇的前mRNA。我们将完成RNA功能组的分析，并阐明与剪接体组分的相互作用，剪接体组分对于在外显子-外显子连接点上游新剪接的mRNA上沉积称为外显子连接复合物（EJC）的多蛋白复合物至关重要。我们将研究EJC核心组件的替代角色我们将鉴定在组蛋白前体mRNA的3 '末端切割中起作用的切割/多聚腺苷酸化因子CPSF的亚基，U 7 snRNP如何募集切割/多聚腺苷酸化因子的子集，以及结合U2 snRNP组分的保守RNA元件如何刺激组蛋白mRNA 3 '端成熟。我们将研究如何microRNP组件，如AGO 2和FXR 1发挥抑制与刺激作用的翻译取决于细胞生长条件，以及microRNA初级转录的加工是否发生在离散的核质位点。这些研究将阐明各种人类疾病的过程，可以追溯到小RNP生物发生，功能和协会的扰动。

DESCRIPTION (provided by applicant): The nuclear steps of messenger RNA biogenesis are orchestrated by small nuclear ribonucleoproteins (snRNPs), which are central players in the action of two spliceosomes and the histone mRNA 3'-end processing machinery. Other classes of snRNPs guide the nucleotide modification of ribosomal RNAs in the nucleolus (snoRNPs) or of spliceosomal snRNAs in Cajal bodies (scaRNPs). A novel class of tiny RNPs, microRNPs, undergoes early biogenesis steps in the nucleus but functions in the cytoplasm to regulate the translation of mRNA targets. The mechanisms of action and biogenesis of snRNPs, scaRNPs and microRNPs will be investigated with an emphasis on the underlying molecular interactions using mammalian cells, the Xenopus oocyte, as well as Drosophila and yeast cells. How these small RNPs and their constituents contribute to the coupling of steps in gene expression is a central focus, including the synergies between and common components used to execute various processes. For box C/D scaRNPs, we will elucidate the signals and factors responsible for their Cajal body localization, which enables their action on spliceosomal snRNAs. We will investigate alternative splicing involving a choice between use of the major (U2-type) or minor (U12-type) spliceosome in the Drosophila prospero pre-mRNA. We will complete analyses of RNA functional groups and elucidate interactions with spliceosome components that are essential for the deposition of a multiprotein complex called the exon junction complex (EJC) on newly spliced mRNA upstream of exon-exon junctions. We will investigate alternative roles of a core component of the EJC (elF4AIII), which we have discovered can functionally replace its yeast homolog, Fall p. We will identify the subunit of the cleavage/polyadenylation factor CPSF that acts in 3'-end cleavage of histone pre- mRNAs, how the U7 snRNP recruits a subset of cleavage/polyadenylation factors, and how a conserved RNA element that binds U2 snRNP components stimulates histone mRNA 3'-end maturation. We will investigate how microRNP components such as AGO2 and FXR1 play repressive versus stimulatory roles in translation depending on cell growth conditions, and whether the processing of microRNA primary transcripts occurs in discrete nucleoplasmic loci. These studies will illuminate a variety of human disease processes that can be traced to perturbations in small RNP biogenesis, functions and associations.