REGULATION OF POLYADENYLATION--THE U1A/U1 SNRNP PARADIGM

真核细胞前信使核糖核酸的转录后调控 (剪接、多聚腺苷、编辑等)是一个重要的控制点 在真核生物中的基因表达。我们最近发现了一种新的形式 基因调控，其中U1a蛋白是U1SnRNP的一个组成部分 参与前信使核糖核酸剪接，负向自动调节自身的生产 通过结合和抑制其自身的前-mRNA的多腺苷基化(38- 41)。U1a和U1a前体信使核糖核酸的复合体结合并阻断 多聚酶(PAP)的活性，该酶催化加成 波利亚尾巴。U1A型自动调节系统是此类系统中的第一个例子。AS 作为最初提案的一部分，我们描述了另一个系统，在该系统中 U1单链RNA相关的70K蛋白也通过抑制多聚腺苷酸化 居住在人民行动党。然而，与U1a的情况不同，70K抑制PAP，而 通过U1 SnRNP复合体间接与前mRNA结合， 与前信使核糖核酸碱基配对。令人惊讶的是，即使U1a存在 在U1的SnRNP复合体中，PAP抑制活性完全位于 70K蛋白。多聚腺苷化抑制基序的发现 在U1a和70K中都是保守的，并在其他蛋白质中发现 通过抑制PAP来调节多聚腺苷的作用将更加广泛。 比之前想象的要好。 本方案的框架是以U1a和70K为例 实现以下目标的基础：1)确定如何 PAP的普遍抑制是通过发现一种调节机制 附加示例，2)表征顺式和交易序列 基序以定义能够控制基因的蛋白质家族 通过抑制PAP的表达，以及3)确定该类型的PF是否 调控可以用来控制外源基因的表达 活着。这一建议的实现将促进基本知识的发展 并表明其调控的普遍性。 U1单链RNA相关蛋白的多聚腺苷酸化。通过阐明 这两种剪接相关蛋白的分子机制 控制多聚腺苷酸化机制，我们将提供对 剪接和聚腺苷酸化之间的竞争，在许多情况下形成 如何管理前mRNAs的交替处理的基础。

Post-transcriptional regulation of the processing of eukaryotic pre-mRNA (splicing, polyadenylation, editing, etc...) is an important control point in gene expression in eukaryotes. We recently discovered a novel form of gene regulation where the U1A protein, a component of the U1 snRNP involved in pre-mRNA splicing, negatively autoregulates its own production by binding to and inhibiting the polyadenylation of its own pre-mRNA (38- 41). The complex between U1A and the U1A pre-mRNA binds to and blocks the activity of polyA polymerase (PAP), the enzyme which catalyzes addition of the polyA tail. U1A autoregulation is the first example of its kind. As part of the original proposal we characterized another system in which the U1 snRNA-associated 70K protein inhabits polyadenylation by also inhabiting PAP. Unlike the case of U1A, however, 70K inhibits PAP while being indirectly bound to the pre-mRNA through the U1 snRNP complex which is base-paired to the pre-mRNA. Surprisingly, even though U1A is present in the U1 snRNP complex, the PAP-inhibitory activity resides entirely with the 70K protein. The discovery that the polyadenylation inhibitory motifs in both U1A and 70K are conserved and are found in other proteins suggests that polyadenylation regulation via PAP inhibition will be more widespread than previously thought. The framework for this proposal is to use the examples of U1A and 70K as a basis to achieve the following goals which are: 1) to determine how prevalent inhibition of PAP is as a regulatory mechanism by finding additional examples, 2) to characterize the cis- and transacting sequence motifs in order to define a family of proteins able to control gene expression via inhibition of PAP, and 3) to determine whether this type pf regulation can be used to control expression of heterologous genes in vivo. The achievement of this proposal will advance fundamental knowledge of pre-mRNA processing and indicate the generality of regulation of polyadenylation by U1 snRNA-associated proteins. By elucidating the molecular mechanisms by which these two splicing-associated proteins control the polyadenylation machinery, we will provide insight into the competition between splicing and polyadenylation that in many cases forms the basis for how alterative processing of pre-mRNAs is governed.