Expression of snRNA genes

描述（由申请人提供）：我们使用人类snRNA基因来研究转录的基本机制。出于一些原因，它们代表了一个很好的模型系统。首先，snRNA基因包含两种类型的启动子，一种由RNA聚合酶（pol） II识别，另一种由pol III识别。pol II和III启动子在结构上非常相似它们确实招募了几种常见的转录因子。因此，在两种启动子上组装的起始复合物的任何差异都可能与RNA聚合酶特异性的测定有关。其次，这些启动子相对简单。核心pol II snRNA启动子（如U1启动子）仅由一个基本元件（近端序列元件或PSE）组成，该元件招募一个称为SNAPc的多亚基因子。核心pol III snRNA启动子如U6启动子包含PSE和TATA box，其募集TATA box结合蛋白TBP。pol II和III snRNA启动子都含有一个激活转录的远端序列元件或DSE，并包含一个募集POU结构域蛋白Oct-1的八聚体序列和一个募集锌指蛋白stf （ZNF143）的SPH位点。第三，我们最近确定了一组定义明确的因子，这些因子是pol III snRNA启动子转录所必需的。这种基础的pol III转录机制的鉴定使我们能够研究它是如何被调节的，事实上我们已经证明CK2可以通过磷酸化该机制中的不同靶点来激活和抑制转录。这种基础的pol - ll转录机制的鉴定使我们能够研究它是如何被调节的。我们建议1)继续表征U6转录的机制，包括SNAPc的结构，U6转录起始复合物的组装，以及Oct-1对该起始复合物组装的影响；2)表征ZNF143和Oct-1如何协同激活来自染色质模板的U6转录；3)确定CK2如何以及何时调控来自人类U6启动子的pol III转录。总之，这些实验将揭示U6转录复合体是如何组装和特异性募集pol -1的，以及在细胞生长和增殖过程中，该复合体的组装和活性是如何受到Oct-1和ZNF143等激活因子以及CK2等激酶的调节的。

DESCRIPTION (provided by applicant): We use the human snRNA genes to study fundamental mechanisms of transcription. They represent an excellent model system for this purpose for a number of reasons. First, snRNA genes contain two types of promoters, one type recognized by RNA polymerase (pol) II and one type recognized by pol III. The pol II and III promoters are very similar in structure and indeed they recruit several common transcription factors. Thus, any difference in the initiation complexes assembled on the two types of promoters is likely to be relevant for the determination of RNA polymerase specificity. Second, these promoters are relatively simple. The core pol II snRNA promoters such as the U1 promoter consist of just one essential element, the proximal sequence element or PSE, which recruits a multisubunit factor called SNAPc. The core pol III snRNA promoters such as the U6 promoter contain a PSE as well as a TATA box, which recruits the TATA box binding protein TBP. Both the pol II and III snRNA promoters contain a distal sequence element or DSE, which activates transcription and contains an octamer sequence that recruits the POU domain protein Oct-1 and a so-called SPH site that recruits the zinc finger protein Staf(ZNF143). Third, we have recently identified a set of well-defined factors required and sufficient for transcription from a pol III snRNA promoter. The identification of this basal pol III transcription machinery allows us to study how it is regulated, and indeed we have shown that CK2 can both activate and repress transcription by phosphorylating different targets within this machinery. The identification of this basal pol lll transcription machinery allows us to study how it is regulated. We propose to 1) continue characterizing the mechanisms of U6 transcription including the architecture of SNAPc, the assembly of the U6 transcription initiation complex, and the impact of Oct-1 on the assembly of this initiation complex; 2) characterize how ZNF143 and Oct-1 cooperate to activate U6 transcription from chromatin templates; and 3) determine how and when CK2 regulates pol III transcription from the human U6 promoter. Together, these experiments will reveal how the U6 transcription complex assembles and specifically recruits pol Ill, and how the assembly and activity of the complex is regulated by activators such as Oct-1 and ZNF143, and by kinases such as CK2, during cell growth and proliferation.