Control of Transcriptional Attenuation of Stress-induced Genes in Yeast

酵母中应激诱导基因转录减弱的控制

• 批准号: 8339240
• 负责人: DAVID E. LEVIN
• 金额: $ 31.1万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-23 至 2016-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8339240
• 关键词: Antifungal Agents; Attenuated; Cell Survival; Cell Wall; Cells; Code; Complex; DNA-Directed RNA Polymerase; Development; Drug Delivery Systems; Elongation Factor; Environment; Failure; Gene Expression; Gene Silencing; Gene Targeting; Genes; Genetic Transcription; Goals; Hand; Human; Link; MAP Kinase Gene; MAPK7 gene; Mediating; Mitogen-Activated Protein Kinases; Modeling; Mutate; Orthologous Gene; Pharmaceutical Preparations; Phosphotransferases; Physiological; Polymerase; Process; Protein Kinase; RNA Polymerase II; Recruitment Activity; Role; Saccharomyces cerevisiae; Series; Signal Pathway; Signal Transduction; Stress; System; Testing; Therapeutic; Transcription Initiation; Transcription Process; Transcriptional Activation; Transcriptional Regulation; Yeasts; attenuation; base; extracellular; gene function; genetic selection; histone modification; novel; novel strategies; premature; promoter; response; small molecule; termination factor; transcription factor; transcription termination

DESCRIPTION (provided by applicant): Cell survival depends on the ability to respond to stress signals from the extracellular environment. Diverse stress signals induce the expression of specific genes that function in the physiologic response to the stress. In the absence of stress, expression of many of these genes is maintained at a minimal level. We have found in the yeast S. cerevisiae, a model eukaryotic system, that the basal expression of many stress-induced genes is minimized by a novel mechanism - premature transcriptional termination, or transcriptional attenuation. Genes induced by cell wall stress require the MAP kinase Mpk1 to carry out two separate steps in the transcription process, neither of which requires its protein kinase activity. The first is to recruit a transcription factor to promoters of target genes. The second involves blocking attenuation, which occurs within the promoter-proximal region of target genes under non-inducing conditions. Attenuation is mediated by the Sen1 termination complex and is blocked by the translocation of Mpk1 to the elongating RNA polymerase (Pol II). Under inducing conditions, gene expression depends upon the relief of attenuation. For Mpk1-induced genes, this happens through the association of Mpk1 with the elongation factor Paf1, which blocks the recruitment of the Sen1 complex to Pol II. This interaction is conserved in the human ortholog of Mpk1, ERK5, suggesting that regulated transcriptional attenuation operates in humans. Based on our preliminary findings, we propose that a wide variety of stress-induced genes are silenced by transcriptional attenuation under non-inducing conditions and that a constellation of transcription factors are likely to relieve attenuation under inducing conditions through interactions with the Paf1C (a complex containing Paf1). The long-term objective of this project is to provide a novel approach to blocking the expression of specific genes, or groups of genes, by inhibiting relief of transcriptional attenuation. We propose to elucidate the mechanisms that regulate transcriptional attenuation and the degree to which various stresses use similar or different attenuation-relief factors to regulate a variety of target genes. One immediate goal will be to determine if other MAP kinases that respond to different signals also function as attenuation-relief factors. Another project will identify non-MAP kinase attenuation- relief factors that allow the induction of a variety of stress-induced genes we have found to be under attenuation control. A third goal will be to understand the role of the Paf1C in the recruitment of the Sen1 termination complex to Pol II. Overall, these studies will yield a mechanistic understanding of regulated transcriptional attenuation and reveal the ubiquity of the process in yeast, which will inform subsequent studies on human cells. PUBLIC HEALTH RELEVANCE: We have discovered a novel mechanism for the control of eukaryotic gene expression - premature transcriptional termination, or transcriptional attenuation. The long-range goal of this project is to provide a novel approach to blocking the expression of specific genes, or groups of genes, by stimulating transcriptional attenuation. We envision the development of small molecule drugs that result in gene silencing by constitutive attenuation, which may be applied to novel anti- fungal therapies, and may extend to therapeutic human gene silencing.

描述（由申请人提供）：细胞存活取决于对细胞外环境的应力信号响应的能力。各种应力信号诱导特定基因的表达，这些基因在对应激的生理反应中起作用。在没有压力的情况下，许多这些基因的表达保持在最低水平。我们已经在模型真核系统的酵母菌中发现，许多应力诱导的基因的基础表达通过一种新型的机制 - 过早的转录终止或转录衰减来最小化。细胞壁应激诱导的基因要求MAP激酶MPK1在转录过程中执行两个单独的步骤，这两种都不需要其蛋白激酶活性。首先是将转录因子募集到靶基因的启动子。第二个涉及阻塞衰减，该衰减发生在非诱导条件下靶基因的启动子促销区域内。衰减是由SEN1终止复合物介导的，并被MPK1转移到伸长的RNA聚合酶（POL II）所阻断。在诱导条件下，基因表达取决于衰减的缓解。对于MPK1诱导的基因，这是通过MPK1与伸长因子PAF1的关联而发生的，该因子PAF1阻止了SEN1复合体向POL II的募集。这种相互作用是在MPK1 ERK5的人类直系同源物中保守的，这表明调节的转录衰减在人类中起作用。根据我们的初步发现，我们建议在非诱导条件下转录衰减会使多种应激诱导的基因沉默，并且转录因子的星座可能通过与PAF1C相互作用（一种含有PAF1的复合物）来缓解诱导条件下的衰减。该项目的长期目标是通过抑制转录衰减的缓解来阻止特定基因或基因组的表达。我们建议阐明调节转录衰减的机制以及各种应力使用相似或不同的浮雕因子来调节各种靶基因的程度。一个直接的目标是确定其他对不同信号响应的MAP激酶是否也起浮雕因素的作用。另一个项目将识别非图激酶衰减 - 救济因素，这些因素允许诱导我们发现的各种压力诱导的基因。第三个目标是了解PAF1C在招募Pol II的SEN1终止综合体中的作用。总体而言，这些研究将对受调节的转录衰减产生机械理解，并揭示该过程在酵母中的无处不在，这将为后来的人类细胞研究提供信息。 公共卫生相关性：我们发现了一种控制真核基因表达的新机制 - 过早的转录终止或转录衰减。该项目的远程目标是通过刺激转录衰减来阻止特定基因或基因组的表达的新方法。我们设想了小分子药物的开发，这些药物通过本构衰减导致基因沉默，该药物可以应用于新型的抗真菌疗法，并可能延伸到治疗性人类基因沉默。