Roles of S. pombe SR proteins in spliceosome function and assembly

描述（由申请人提供）：人类中大多数基因表达的一个重要步骤是去除内含子，内含子通过大的动态剪接体复合物从前mRNA中剪接出来。已经表明，人类中的绝大多数遗传性疾病是由内含子的不正确去除引起的。人类SR蛋白是重要的剪接因子，对剪接体的功能和调节至关重要。更具体地说，它们已被证明在剪接体组装以及剪接反应的后续步骤中发挥重要作用。SR蛋白水平的改变已被证明会导致许多人类疾病，如癌症和HIV。鉴于SR家族的9种蛋白质、组织特异性表达水平和可变剪接中的复杂作用，在人类中区分单个SR蛋白的作用已被证明是困难的。为了区分SR蛋白在遗传上易处理的系统中的全基因组作用，将利用单细胞模式生物粟酒裂殖酵母。在S.粟酒酵母有许多内含子，含有与人类相似的特征。鉴于S.在粟酒裂殖酵母中，只有少数内含子被测试依赖于SR蛋白进行最佳剪接。此外，许多已被证明与人SR蛋白相互作用的剪接因子也存在于S。虽然只观察到其中几种相互作用，但目前缺乏全面的分析。利用酵母独有的遗传技术以及从人体实验中改编的生化分析，拟议的研究将确定SR蛋白如何与S.粟酒裂殖酵母（AIM1），以及它们在有效去除该模式生物（AIM2）中存在的许多独特内含子中在全基因组范围内发挥什么作用。此外，拟议的研究将确定SR蛋白如何影响剪接在S。通过分析特定内含子（AIM 3）上的剪接体组装，对SR蛋白如何与S.粟酒裂殖酵母将告知SR蛋白的一般机制和剪接体作为一个整体加工前mRNA的基本过程。

DESCRIPTION (provided by applicant): An essential step in the expression of the majority of genes in humans is the removal of introns, which are spliced out of pre-mRNA by the large and dynamic spliceosome complex. It has been indicated that a significant majority of hereditary disease in humans is caused by the incorrect removal of introns. SR proteins in humans are important splicing factors that have been shown to be essential for spliceosome function and regulation. More specifically, they have been shown to play essential roles in spliceosome assembly as well as later steps of the splicing reaction. Altered levels of SR proteins have been shown to result in many human diseases such as cancer and HIV. Distinguishing the roles of individual SR proteins has proven difficult in humans given the nine-protein SR family, tissue specific expression levels, and complex roles in alternative splicing. In order to distinguish the roles of SR proteins genome-wide in a genetically tractable system, the unicellular model organism Schizosaccharomyces pombe will be utilized. There are only two SR proteins in S. pombe with many introns containing similar characteristics with humans. Given the diverse intron structure of the many introns in S. pombe only a few introns have been tested for reliance on SR proteins for optimal splicing. In addition, many of the splicing factors that have been shown to interact with human SR proteins are also present in S. pombe although only a few of these interactions have been observed and a thorough analysis is currently lacking. Using genetic techniques that are uniquely available to yeast as well as biochemical assays adapted from experiments in humans, proposed studies will determine how SR proteins interact with the spliceosome in S. pombe (AIM1) and what role they play genome-wide in the efficient removal of the many unique introns that are present in this model organism (AIM2). In addition, proposed studies will determine the mechanism of how SR proteins influence splicing in S. pombe by analyzing spliceosome assembly on specific introns (AIM3). The fundamental understanding of how SR proteins function with the diverse set of introns in S. pombe will inform general mechanisms of SR proteins and the essential process of pre-mRNA processing by the spliceosome as a whole.