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.

特定基因组的空间和时间表达对于复杂的执行至关重要 差异化计划。这项研究的长期目标是机械地定义瞬时转录 出芽酵母减数分裂分化程序的背景。减数分裂标志所需的许多基因 事件在有丝分裂细胞分裂期间受到抑制，但随后在时间发育过程中短暂诱导 波浪分为“早波”、“中波”和“晚波”。 Ume6p 结合“早期”减数分裂基因启动子并介导其 通过招募组蛋白脱乙酰酶（HDAC）和染色质重塑复合物来进行植物抑制。 我们最近发现早期减数分裂基因诱导需要 Cdc20p- 破坏 Ume6p 定向后期促进复合物/环体（APC/C）泛素连接酶。尽管因其在其中的作用而闻名 控制有丝分裂细胞中的 G2 -> M 转变，这是 APC/CCdc20 靶向转录的第一份报告 破坏因素。此外，Ume6p 的破坏仅限于进入减数分裂的细胞，尽管 APC/CCdc20 在有丝分裂细胞分裂期间处于活跃状态（并且存在 Ume6p）。减数分裂诱导剂 Ime1p 提供 触发促进 Ume6p 破坏，从而提出 APC/C 底物选择的新机制 在差异化计划的背景下被重定向。 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 SAGA 的底物。深入研究的乙酰化 核小体的脱乙酰化分别维持染色质处于“开放”和“闭合”构型。 然而，转录因子的乙酰化此前尚未在酵母中得到证实，并且仅被证实。 已描述了哺乳动物系统中的一些反式激活因子。据我们所知，Ume6p 是第一个 发现转录抑制因子被乙酰化。有趣的是，初步结果表明乙酰化的作用 既阻止 Ume6p DNA 结合能力又增强其降解。这些发现提出了一个新的 通过直接抑制 Ume6p 阻遏物功能的 Gcn5p 依赖性转录激活模型。 诱导后，减数分裂基因表达和标志性事件的执行通过 系列检查站系统。初步结果表明 Ume6p 激活后被阻止破坏 DNA 损伤检查点。保护 Ume6p 免遭破坏的机制 检查点激活或其他检查点通路的作用尚不清楚。了解分子 减数分裂诱导后 Ume6p 依赖性抑制得以缓解的机制，以及抑制是如何发生的 为响应检查站路径而重新建立，提出以下目标： 目标1。剖析指导 APC/C 发育重新分配的分子机制。 目标2。确定乙酰化在 Ume6p 活性和调节中的作用。 目标3。识别并表征介导 Ume6p 破坏的减数分裂途径。