The Structure and Function of Perinucleolar Compartment

描述(由申请人提供)：我们的长期目标是了解PNC的结构和功能及其在恶性肿瘤中的作用。核仁周围区(PNC)是一种定位于核仁周围的非膜结合的多组分核亚结构。我们发现它在体外和体内的恶性转化中都是独一无二的。PNC富含PolIII新合成的RNA和主要参与PolII RNA加工的RNA结合蛋白。我们的初步发现表明，PNC相关的RNA与一些已知的PolII RNA结合蛋白在相同的复合体中。这些新的复合体并不局限于PNC，因为在没有PNC的正常细胞中也可以检测到PTB-MRP RNA相互作用。然而，在癌变过程中，这些复合体的水平或调节可能会发生变化，导致这些复合体在PNC中成核。这些发现导致了我们的工作模型，在该模型中，PNC与新合成的PolIII RNA在恶性肿瘤期间的代谢有关，并且可能代表着新的分子复合体的变化。本提案的目标是通过鉴定和初步表征这些新的RNP来开始检验这一假说，使用RNase MRP RNA(PNC的真正成分之一)作为第一个例子，并开始使用细胞生物学方法解决这些RNP与PNC的功能关联。由于目前对PolIII小非编码RNA的转录后处理和调控知之甚少，因此解决新的RNPs不仅对于理解PNC的结构和功能非常重要，而且还应该揭示一种参与这些功能RNA转录后调控的新机制。

DESCRIPTION (provided by applicant): Our long-term goal is to understand the structure and function of the PNC and its roles in malignancy. The perinucleolar compartment (PNC) is a multicomponent non-membrane bound nuclear substructure that localizes to the nucleolar periphery. We have found it to be unique to malignant transformation both in vitro and in vivo. The PNC is enriched with RNA newly synthesized by pol III and RNA binding proteins primarily implicated in pol II RNA processing. Our preliminary findings show that the PNC-associated RNAs are in the same complexes with some of the known pol II RNA binding proteins. These novel complexes are not restricted to the PNC since PTB-MRP RNA interactions can also be detected in normal cells without PNCs. However, the levels or the regulations of these complexes may change during malignancy, leading to the nucleation of these complexes in the PNC. These findings lead to our working model in which the PNC is associated with and may represent changes in novel molecular complexes that are involved in the metabolism of newly synthesized pol III RNA during malignancy. The goal of this proposal is to begin test this hypothesis by identifying and initially characterizing these novel RNPs, using RNase MRP RNA (one of the bona fide components of the PNC) as the first example, and by beginning to address the functional association of these RNPs with the PNC using cell biological approaches. As little is understood regarding the post-transcriptional processing and regulation of the pol III small non-coding RNAs, the solution of the novel RNPs is not only important for the understanding of PNC structure and function, but should also reveal a novel mechanism involved in the post-transcriptional regulation of these functional RNAs.