Mechanisms of Transient Transcription in Yeast

酵母瞬时转录机制

• 批准号: 8323555
• 负责人: RANDY S STRICH
• 金额: $ 14.98万
• 依托单位: UNIV OF MED/DENT NJ-SCH OSTEOPATHIC MED
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8323555
• 关键词: Acetylation; Binding; Biochemical Genetics; Biological Assay; Cell division; Cells; Chromatin; Chromatin Remodeling Factor; Chromosome Segregation; Complex; Coupled; DNA Binding; DNA Damage; DNA Maintenance; DNA damage checkpoint; Deacetylation; Defect; Development; Embryo; Event; Failure; G2/M Transition; Gcn5p; Gene Expression; Genes; Genetic Transcription; Goals; Histone Deacetylase; In Vitro; Lead; Ligase; Mediating; Meiosis; Meiotic Recombination; Mitotic; Modeling; Modification; Molecular; Monitor; Nucleosomes; Pathway interactions; Play; Proteins; Recruitment Activity; Regulation; Reporting; Repression; Role; SAGA; Saccharomycetales; Series; Signal Transduction; System; Testing; Time; Trans-Activators; Transcription Repressor/Corepressor; Transcriptional Activation; Yeasts; anaphase-promoting complex; gene induction; histone acetyltransferase; in vivo; prevent; programs; promoter; research study; response; transcription factor; ubiquitin ligase

The spatial and temporal expression of specific gene sets is critical for the execution of complex differentiation programs. The long-term goal of this study is to mechanistically define transient transcription in the context of the budding yeast meiotic differentiation program. Many genes required for the meiotic landmark events are repressed during mitotic cell division but then transiently induced during development in temporal waves termed "early", "middle" and "late". Ume6p binds "early" meiotic gene promoters and mediates their vegetative repression by recruiting both histone deacetylase (HDAC) and chromatin remodeling complexes. We have recently discovered that early meiotic gene induction requires Ume6p destruction by the Cdc20p- directed anaphase promoting complex/cyclosome (APC/C) ubiquitin ligase. Although well known for its role in controlling the G2 -> M transition in mitotic cells, this is the first report that APC/CCdc20 targets a transcription factor for destruction. In addition, Ume6p destruction is restricted to cells entering meiosis, even though APC/CCdc20 is active (and Ume6p is present) during mitotic cell division. The meiotic inducer Ime1p provides a trigger to promote Ume6p destruction thus suggesting a new mechanism by which APC/C substrate selection is redirected within the context of a differentiation program. While searching for potential meiosis-specific destruction signals, we discovered that Ume6p is a substrate of the Gcn5p histone acetyltransferase (HAT) complex called SAGA. The well-studied acetylation and deacetylation of nucleosomes maintains chromatin in "open" and "closed" configurations, respectively. However, the acetylation of transcription factors has not been demonstrated previously in yeast and has only been described for a few transactivators in mammalian systems. To our knowledge, Ume6p is the first transcriptional repressor found to be acetylated. Interestingly, preliminary results point to a role for acetylation in both preventing Ume6p DNA binding ability and enhancing its degradation. These findings suggest a new model for Gcn5p-dependent transcriptional activation through direct inhibition of Ume6p repressor function. Following induction, meiotic gene expression and the execution of landmark events are coupled by a series of checkpoint systems. Preliminary results indicate that Ume6p destruction is prevented upon activation of the DNA damage checkpoint. The mechanism by which Ume6p is protected from destruction following checkpoint activation, or the role of additional checkpoint pathways, is unknown. To understand the molecular mechanisms by which Ume6p-dependent repression is relieved upon meiotic induction, and how repression is reestablished in response to checkpoint pathways, the following aims are proposed: Aim1. Dissect the molecular mechanisms directing developmental re-tasking of the APC/C. Aim2. Determine the role that acetylation plays in Ume6p activity and regulation. Aim3. Identify and characterize the meiotic pathways that mediate Ume6p destruction.

特定基因集的空间和时间表达对于复杂的执行至关重要 分化计划。这项研究的长期目标是机械地定义瞬态转录 发芽的酵母减少分化计划的背景。减数分裂地标所需的许多基因 事件在有丝分裂细胞分裂期间被抑制，但随后在时间上发育过程中暂时诱导 波浪称为“早期”，“中间”和“晚”。 UME6P绑定“早期”减数分裂基因启动子并介导其 通过募集组蛋白脱乙酰基酶（HDAC）和染色质重塑络合物来抑制营养抑制。 我们最近发现，早期的减数分裂基因诱导需要CDC20P-的UME6P破坏 定向后期促进复合体/循环体（APC/C）泛素连接酶。尽管以其在 控制有丝分裂细胞中的G2-> M转变，这是APC/CCDC20靶向转录的第一个报告 破坏因素。此外，即使 有丝分裂细胞分裂期间，APC/CCDC20活性（并且存在UME6P）。减数分裂诱导剂IME1P提供了 触发促进UME6P销毁 在差异程序的上下文中重定向。 在寻找潜在的减数分裂特异性破坏信号时，我们发现UME6P是一个 GCN5P组蛋白乙酰转移酶（HAT）复合物的底物称为SAGA。研究良好的乙酰化 核小体的脱乙酰化分别在“开放”和“封闭”构型中保持染色质。 但是，转录因子的乙酰化以前尚未在酵母中证明，仅具有 描述了哺乳动物系统中的一些反式激活剂。据我们所知，UME6P是第一个 转录阻遏物被发现是乙酰化的。有趣的是，初步结果表明乙酰化的作用 两者都可以防止UME6P DNA结合能力和增强其降解。这些发现暗示了一个新的 通过直接抑制UME6P抑制器函数，依赖GCN5P的转录激活的模型。 诱导后，减数分裂基因的表达和地标事件的执行是由 一系列检查点系统。初步结果表明激活后阻止UME6P破坏 DNA损伤检查点的。 UME6P免受破坏的机制 检查点激活或其他检查点途径的作用是未知的。了解分子 通过减数分裂诱导及其抑制作用的抑制作用以及如何抑制的机制 为了响应检查点途径而重新建立，提出了以下目的： AIM1。解剖指导APC/C的发育重新任务的分子机制。 AIM2。确定乙酰化在UME6P活性和调节中起作用的作用。 AIM3。识别并表征介导UME6P破坏的减数分裂途径。