Determining the function and mechanism of the MALAT1 long non-coding RNA in co-transcriptional splicing

项目摘要 许多长链非编码RNA（lncRNA）已被证明是突变或异常表达的 在人类癌症中。其中最常见的是一种称为转移相关肺的lncRNA 腺癌转录本1（MALAT 1）。MALAT 1代表了一个理想的模型来研究的作用， lncRNA在驱动癌症中的作用，因为它的过表达与基因组中剪接的错误调节有关。 肺腺癌、乳腺癌、胰腺癌、结肠癌、前列腺癌和肝细胞癌。第二、 在动物模型中的研究表明，MALAT 1作为一种致癌基因， 肿瘤和转移。尽管MALAT 1作为许多癌症的关键驱动因素具有明显的重要性， MALAT 1在正常细胞条件下的功能作用是未知的。 哺乳动物中的剪接主要通过共转录机制发生， 剪接因子在RNA聚合酶转录时被募集到新生的前mRNA中 二.虽然很明显，RNA聚合酶II（RNA PolII）的C-末端结构域（CTD）是必需的， 对于有效的剪接，剪接因子如何被共转录募集并与RNA PolII相互作用 不明最近，我们的研究小组发现，MALAT 1定位于大多数人的基因组DNA， 活跃转录RNA PolII基因，并且这种定位发生在转录依赖的 方式此外，已知MALAT 1定位于核斑点，即一个核隔室， 富含剪接因子。基于这些结果，我们假设MALAT 1可能作为 难以捉摸的分子连接RNA PolII和剪接机制，这是需要有效的合作， 哺乳动物前体mRNA的转录募集和剪接。 我假设MALAT 1作为RNA聚合酶II和RNA聚合酶之间的分子支架， 剪接机器以协调共转录剪接。本提案的目标1将描述 直接结合MALAT 1以协调共转录剪接的因子。目标2将确定是否 MALAT 1表达与剪接缺陷直接相关。最后，在目标3中， MALAT 1丰度和癌症将被探索。综合起来，这些结果将提供 对转录和剪接的变革性理解，它们如何在细胞中协调， 这些过程是如何通过MALAT 1（一种单一的lncRNA）被破坏以驱动癌症的。

PROJECT SUMMARY Many long non-coding RNAs (lncRNAs) have been shown to be mutated or aberrantly expressed in human cancers. One of the most common is a lncRNA called metastasis-associated lung adenocarcinoma transcript 1 (MALAT1). MALAT1 represents an ideal model to study the role of lncRNAs in driving cancer because its overexpression is associated with mis-regulation of splicing in lung adenocarcinoma, breast, pancreatic, colon, prostate and hepatocellular carcinomas. Second, studies in animal models have shown that MALAT1 acts as an oncogene and promotes aggressive tumors and metastasis. Despite the clear importance of MALAT1 as a critical driver of many cancers, the functional role of MALAT1 in normal cellular conditions is unknown. Splicing in mammals occurs through a predominantly co-transcriptional mechanism such that splicing factors are recruited to nascent pre-mRNAs as they are being transcribed by RNA Polymerase II. Although it is clear that the C-terminal domain (CTD) of RNA Polymerase II (RNA PolII) is required for efficient splicing, how splicing factors are recruited co-transcriptionally and interact with RNA PolII is unknown. Recently, our group showed that MALAT1 localizes to the genomic DNA of the majority of actively transcribed RNA PolII genes and that this localization occurs in a transcriptionally dependent manner. Additionally, MALAT1 is known to localize to nuclear speckles, a nuclear compartment that is enriched for splicing factors. Based on these results, we hypothesized that MALAT1 might act as the elusive molecular link connecting RNA PolII and the splicing machinery that is required for efficient co- transcriptional recruitment and splicing of mammalian pre-mRNA. I hypothesize that MALAT1 acts as a molecular scaffold between RNA Polymerase II and splicing machinery to coordinate co-transcriptional splicing. Aim 1 of this proposal will characterize factors that directly bind to MALAT1 to coordinate co-transcriptional splicing. Aim 2 will identify if MALAT1 expression is directly linked to splicing defects. Finally, in Aim 3, the relationship between MALAT1 abundance and cancer will be explored. Taken together, these results would provide a transformative understanding of transcription and splicing, how they are coordinated in the cell, and how these processes might be disrupted through MALAT1 – a single lncRNA – to drive cancer.