Function of snRNP particles in pre-mRNA splicing

snRNP颗粒在mRNA前体剪接中的功能

• 批准号: 6866579
• 负责人: Brian C. Rymond
• 金额: $ 27.41万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-07-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6866579
• 关键词: RNA splicing; fungal genetics; intermolecular interaction; introns; microarray technology; molecular assembly /self assembly; nucleic acid sequence; precursor mRNA; protein structure function; small nuclear ribonucleoproteins; spliceosomes; yeasts

DESCRIPTION (provided by applicant): The pre-mRNA transcripts of most mammalian genes contain multiple introns that must be precisely removed before the mRNA can be used in protein synthesis. For many genes, this pre-mRNA splicing reaction is regulated by developmental or environmental signals. Errors in the splicing pathway can have devastating health consequences and account for approximately 15% of all known human genetic disorders. The diagnosis and treatment of splicing-related disorders will profit by a better understanding of the cellular rules governing intron removal. The pre-mRNA splicing enzyme, or spliceosome, is a large ribonucleoprotein complex composed of over 70 proteins and 5 small nuclear RNAs. A widely cited model of spliceosome assembly, activation, and disassembly (or the spliceosome cycle) has evolved from the results of in vitro experimentation conducted over the last 15 years. The modulation of splicing efficiency and alterative splice site selection often can be explained by changes in spliceosome assembly observed in the presence or absence of specific regulator proteins (or cis-acting elements). The recent isolation from yeast of a U2,U5,U6 ribonucleoprotein (RNP) complex reminiscent of a late stage or post-catalytic spliceosome supports this spliceosome cycle model. In contrast, the identification of what appears to be a fully assembled but pre-mRNA-free "penta-snRNP" spliceosome from yeast raises the question of whether spliceosome disassembly actually occurs in vivo. We will address this apparent discrepancy by tests of two hypotheses. First, that a spliceosome cycle occurs within cells and progresses through a series of splicing factor-dependent assembly and disassembly steps. Second, that the Clf1p assembly factor facilitates integration of the prespliceosome with the U4/U6.U5 tri-snRNP particle through branchpoint reorganization that includes the recruitment of RNA export factors. This work will provide new experimental tools for the analysis of RNA processing and generate conceptual frameworks from which to view spliceosome assembly and the integration of the pre-mRNA splicing and RNA export pathways in living cells.

描述（由申请人提供）：大多数哺乳动物基因的前mRNA转录物含有多个内含子，在mRNA可用于蛋白质合成之前必须精确去除内含子。对于许多基因，这种前mRNA剪接反应受发育或环境信号的调节。剪接途径中的错误可能会对健康造成破坏性后果，约占所有已知人类遗传疾病的15%。剪接相关疾病的诊断和治疗将受益于更好地了解内含子去除的细胞规则。前mRNA剪接酶或剪接体是由70多种蛋白质和5种小的核RNA组成的大的核糖核蛋白复合物。一个被广泛引用的剪接体组装、激活和拆卸（或剪接体循环）模型已经从过去15年进行的体外实验的结果发展而来。剪接效率和可变剪接位点选择的调节通常可以通过在存在或不存在特定调节蛋白（或顺式作用元件）的情况下观察到的剪接体组装的变化来解释。最近从酵母中分离出的U2，U 5，U6核糖核蛋白（RNP）复合物使人联想到晚期或后催化剪接体，支持这种剪接体循环模型。相比之下，从酵母中鉴定出似乎完全组装但不含前mRNA的“penta-snRNP”剪接体，这引发了剪接体解体是否真的在体内发生的问题。我们将通过两个假设的检验来解决这个明显的差异。首先，剪接体循环发生在细胞内，并通过一系列剪接因子依赖的组装和拆卸步骤进行。第二，Clf 1 p组装因子通过分支点重组促进前剪接体与U4/U6.U5 tri-snRNP颗粒的整合，包括RNA输出因子的募集。这项工作将为RNA加工的分析提供新的实验工具，并产生概念框架，从该框架中查看剪接体组装和前mRNA剪接和RNA输出途径在活细胞中的整合。