REGULATED POLYADENYLATION OF MESSENGER RNA

描述：（改编自申请人摘要）本研究者 以前的研究表明，从非洲爪蟾白蛋白mRNA分离， 细胞质或细胞核部分具有异常短且离散的17个残基 poly（A）尾。随后在一个类似的短poly（A）尾上鉴定出一个类似的短poly（A）尾。 许多其他的mRNA在转录后受到调节， 类似于白蛋白mRNA，并证明短poly（A）尾是 未加工的核白蛋白前RNA的特征。短poly（A）尾导致 由于多聚腺苷酸限制性元件（PLE）的存在， 白蛋白基因基于数据的搜索已经确定了数百个基因与PLE 类似的元素，该调查员演示了PLE的功能 在编码HIV-EP 2/Schnurri 2的基因中，锌指转录因子 激活HIV-1前病毒的转录。整体 结果表明，至少有两类多聚腺苷酸化的mRNA; 那些以200+ poly（A）尾离开细胞核的，以及那些离开细胞核的， 核具有离散的，<20 nt的poly（A）尾。本提案的总体目标是 是确定负责调节poly（A）尾的分子机制 长度，并确定这一进程对 具有短聚腺苷酸尾的mRNA的代谢和翻译。具体目标 因此，本项目的目的是：1）识别和表征核PLE 结合蛋白（PLE-BP）; 2）确定功能的相互作用， 为了阐明PLE和PLE-BP调节PLE-BP的机制， poly（A）尾长;和3）确定以下的功能后果： 限制聚（A）在mRNA从细胞中输出时少于20个核苷酸。 细胞核，对稳定和不稳定的mRNA的周转，以及对 翻译.

DESCRIPTION: (Adapted from the applicant's abstract) This investigator previously showed that Xenopus albumin mRNA isolated from either the cytoplasmic or nuclear fractions has an unusually short and discrete 17 residue poly(A) tail. A similarly short poly(A) tail was subsequently identified on a number of other mRNAs that were post-transcriptionally regulated in a manner similar to the albumin mRNA and demonstrated that the short poly(A) tail was feature of unprocessed nuclear albumin pre-RNA. The short poly(A) tail results from the presence of a poly(A)-limiting element (PLE) in the terminal exon of the albumin gene. A data based search has identified hundreds of genes with PLE like elements and this investigator demonstrated the functionality of the PLE in the gene encoding the HIV-EP2/Schnurri 2, a zinc finger transcription factor that activates transcription of the integrated HIV-1 provirus. The overall results suggest that there are at least two categories of polyadenylated mRNAs; those that exit the nucleus with a 200+ poly(A) tail, and those that exit the nucleus with a discrete, <20 nt poly(A) tail. The overall goal of this proposal is to define the molecular mechanism responsible for regulating poly(A) tail length, and to define the functional consequences of this process on the metabolism and translation of mRNAs with short poly(A) tails. The specific aims of this project therefore seek to 1) identify and characterize the nuclear PLE binding protein (PLE-BP); 2) to determine the functional interactions of the PLE-BP in order to elucidate the mechanisms by which PLE and PLE-BP regulate poly(A) tail length; and 3) to determine the functional consequences of limiting poly(A) to less than 20 nucleotides on export of mRNA from the nucleus, on the turnover of both stable and unstable mRNAs, as well as on translation.