Expression of snRNA genes

描述(申请人提供)：我们使用人类SnRNA基因来研究基本的转录机制。出于许多原因，它们代表了用于这一目的的极好的模式系统。首先，SnRNA基因包含两种类型的启动子，一种由RNA聚合酶(PolII)识别，另一种由PolIII识别。PolII和PolIII的启动子在结构上非常相似，确实它们招募了几个共同的转录因子。因此，在两种类型的启动子上组装的起始复合体的任何差异都可能与确定RNA聚合酶的特异性有关。其次，这些推动者相对简单。POLII的核心SnRNA启动子，如U1启动子，只由一个基本元件组成，即近端序列元件或PSE，它招募一种称为SNAPc的多亚基因子。核心的polIII单链RNA启动子，如U6启动子，包含一个PSE和一个TATA盒，它招募TATA盒结合蛋白TBP。PolII和III的SnRNA启动子都包含一个激活转录的末端序列元件或DSE，并包含一个招募POU结构域蛋白Oct-1的八聚体序列和一个招募锌指蛋白Staf(ZNF143)的所谓SPH位点。第三，我们最近确定了一组从PolIII SnRNA启动子转录所需的和充分的定义明确的因子。对这个基本的polIII转录机制的鉴定使我们能够研究它是如何被调控的，实际上我们已经证明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。对这一基本的Pol11转录机制的鉴定使我们能够研究它是如何被调控的。我们建议1)继续研究U6转录的机制，包括SNAPc的结构，U6转录起始复合体的组装，以及OCT-1对该起始复合体组装的影响；2)表征ZNF143和OCT-1如何协同激活染色质模板中的U6转录；以及3)确定CK2如何以及何时调控人类U6启动子的PolIII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招募PolIll的，以及在细胞生长和增殖过程中，复合体的组装和活性如何受到OCT-1和ZNF143等激活剂以及CK2等激酶的调节。

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.