Transcriptional Repression by Maf1 in Yeast

描述（由申请人提供）：rRNA和tRNA的合成通过肿瘤抑制因子（例如p53和Rb）和癌基因（例如c-myc）的功能与细胞分裂密切相关。这些蛋白质的转化形式直接靶向RNA聚合酶（pols）I和III并通过RNA聚合酶（pols）I和III沿着重要细胞周期调节因子的表达上调转录。Maf 1蛋白是一种独特的转录调节因子，其在人类细胞中的性质与p53和Rb相似。人Maf 1是一种候选肿瘤抑制因子，负调控所有三种核RNA聚合酶的转录。Maf 1如何实现其对转录的影响尚不清楚，并且由于蛋白质不包含任何已知功能的基序而变得复杂。In S. Maf 1是通过RNA聚合酶III抑制转录所必需的，并且其功能是整合来自协调调节核糖体和tRNA合成的多种营养和应激信号通路的响应。这些途径，就像Maf 1本身一样，并没有很好的定义。Maf 1在酵母中pol III转录抑制中的普遍需求为理解调节核糖体和tRNA合成的途径和机制以及这种新型信号整合剂的生化功能提供了非常有价值的模型。因此，本研究的长期目标是了解Maf 1的结构/功能关系，其与调控靶点的相互作用以及其与上游信号分子的相互作用，这些信号分子通过翻译后机制影响Maf 1依赖的转录抑制。这些目标将通过明确定义的体外系统中的生化研究和通过应用磷酸肽鉴定的创新方法来实现。此外，强大的全基因组和系统的遗传和生物化学方法将被用来确定蛋白激酶和其他分子参与信号抑制Maf 1。最后，通过对Maf 1三维结构的测定，进一步了解Maf 1的功能和调控。 公共卫生相关性：Maf 1是一种潜在的肿瘤抑制因子，在哺乳动物细胞中负调节所有三种核RNA聚合酶的转录。在酵母中，Maf 1是RNA聚合酶III转录抑制的重要介质，并整合了协调调节核糖体和tRNA合成的多种营养和应激信号通路的反应。我们对Maf 1的遗传、生化和结构研究将增强对可能影响癌症生物学的基本细胞过程的理解。

DESCRIPTION (provided by applicant): The synthesis of rRNAs and tRNAs is intimately linked with cell division through the function of tumor suppressors (e.g. p53 and Rb) and oncogenes (e.g. c-myc). The transforming forms of these proteins directly target and up-regulate transcription by RNA polymerases (pols) I and III along with the expression of important cell cycle regulators. The Maf1 protein is a unique regulator of transcription whose properties in human cells are similar to p53 and Rb. Human Maf1 is a candidate tumor suppressor that negatively regulates transcription by all three nuclear RNA polymerases. How Maf1 achieves its effects on transcription is not understood and is complicated by the fact that the protein does not contain any motifs of known function. In S. cerevisiae, Maf1 is essential for repressing transcription by RNA polymerase III and functions to integrate the responses from multiple nutritional and stress signaling pathways that coordinately regulate ribosome and tRNA synthesis. These pathways, like Maf1 itself, are not well defined. The universal requirement for Maf1 in pol III transcriptional repression in yeast provides an extraordinarily valuable model for understanding the pathways and mechanisms regulating ribosome and tRNA synthesis and the biochemical function of this novel signal integrator. Accordingly, the long-term goal of this research is to understand Maf1 structure/function relationships, its interactions with regulatory targets and its interactions with upstream signaling molecules that operate via posttranslational mechanisms to affect Maf1-dependent transcriptional repression. These aims will be achieved through biochemical studies in well-defined in vitro systems and through the application of an innovative method for phosphopeptide identification. In addition, powerful genome-wide and systematic genetic and biochemical approaches will be used to identify protein kinases and other molecules involved in signaling repression by Maf1. Finally, our understanding of the function and regulation of Maf1 will be advanced by the determination its three-dimensional structure. PUBLIC HEALTH RELEVANCE: Maf1 is a potential tumor suppressor that negatively regulates transcription by all three nuclear RNA polymerase in mammalian cells. In yeast, Maf1 is an essential mediator of transcriptional repression by RNA polymerase III and integrates the responses from multiple nutritional and stress signaling pathways that coordinately regulate ribosome and tRNA synthesis. Our genetic, biochemical and structural studies on on Maf1 will enhance understanding of fundamental cellular processes that are likely to impact cancer biology.