CAREER: Core Promoter-Selective Transcription by RNA Polymerase II

真核蛋白质编码基因的差异转录调控是在多个水平上调控的，涉及调控DNA序列和核心启动子DNA元件的组合作用。核心启动子是包含基因转录起始点的最小DNA区域，该区域被普遍存在的基础/一般转录机制识别，并足以在体外指导RNA聚合酶II的特异性转录起始。相比之下，调控DNA序列位于距离核心启动子不同的距离，并被各种序列特异性的DNA结合转录调控因子识别，这些转录调控因子可以是组织特异性的或发育调节的，并影响核心启动子上基础转录机制的招募或活性。因此，核心启动子和相关的基础转录机制是转录调控信号的最终靶标。值得注意的是，核心启动子的结构不仅影响启动子的基本活性，而且影响其对特定增强子和转录调节因子的选择性反应。然而，核心启动子对基因选择性转录调控的作用尚不清楚。各种核心启动子DNA元件已被鉴定，包括TATA盒、启动子、DPE和其他。除了塔塔盒子之外，其他元素的功能仍然没有得到很好的描述。令人惊讶的是，最近对果蝇和人类的分析显示，大多数蛋白质编码基因都缺乏TATA框。尽管对含有TATA盒的基因的转录启动和调控机制已经了解很多，但对于更大类别的TATA缺失基因的转录启动的基本机制和机制仍然知之甚少。Martinez博士之前的工作表明，在没有TATA的核心启动子中，存在特定于核心启动子的基本因子和特定转录启动的替代途径。该项目的具体研究目标是(I)从非TATA启动子中提纯和鉴定启动子功能和启动子依赖转录所必需的核心启动子特异的基本因子，以及(Ii)在体外和人类细胞中表征这些核心启动子特异的基本因子的分子功能。通过这个项目的教育部分(分子生物学、转录和染色质的本科生和研究生课程，以及开发一门新的本科实验室课程，重点是基因调控、染色质和细胞信号研究)，生物化学和分子生物学的本科生、研究生和博士后教育和培训将得到加强。将强调少数族裔学生在加州大学河滨分校的参与。马丁内斯博士实验室的少数族裔本科生一直在参加包括加州少数族裔参与科学联盟(CAMP)计划在内的各种“少数族裔准入计划”。

Differential transcription regulation of eukaryotic protein-coding genes is controlled at multiple levels and involves the combinatorial function of regulatory DNA sequences and core promoter DNA elements. The core promoter is the minimal DNA region encompassing the transcription start site of a gene that is recognized by the ubiquitous basal/general transcription machinery and is sufficient to direct specific transcription initiation by RNA polymerase II in vitro. In contrast, regulatory DNA sequences are located at varying distances from the core promoter and are recognized by a variety of sequence-specific DNA-binding transcription regulators, which can be tissue-specific or developmentally regulated and influence the recruitment or activity of the basal transcription machinery at the core promoter. Thus, the core promoter and the associated basal transcription machinery are the ultimate targets of transcription regulatory signals. Significantly, the structure of the core promoter influences not only the basal activity of a promoter but also its selective response to specific enhancers and transcription regulators. How core promoters contribute to gene-selective transcription regulation is however unclear. Various core promoter DNA elements including the TATA box, the initiator, the DPE, and others have been identified. With the exception of the TATA box, the functions of the other elements are still poorly characterized. Surprisingly, recent analyses in Drosophila and humans have revealed that most protein-coding genes lack a TATA box. Although much has been learned about the mechanisms of transcription initiation and regulation of TATA box-containing genes, the basal machinery and the mechanisms of transcription initiation at the larger class of TATA-less genes remain poorly understood. Previous work by Dr. Martinez has indicated the existence of core promoter-specific basal factors and alternative pathways for specific transcription initiation at TATA-less core promoters. The specific research goals of this CAREER project are (i) to purify and identify the core promoter-specific basal factors that are essential for initiator function and initiator-dependent transcription from TATA-less promoters and (ii) to characterize the molecular functions of these core promoter-specific basal factors in vitro and in human cells. Through the educational component of this project (undergraduate and graduate courses in molecular biology, transcription and chromatin, and the development of a new undergraduate laboratory course focused on research in gene regulation, chromatin, and cell signaling), undergraduate, graduate and postdoctoral education and training in biochemistry and molecular biology will be enhanced. Participation of minority students at the University of California-Riverside will be emphasized. Undergraduate minority students in Dr. Martinez's laboratory have been participating in various "minority access programs" including the California Alliance for Minority Participation in Science (CAMP) program.