Chromatin Mechanisms of Neuronal Maturation

神经元成熟的染色质机制

• 批准号: 9333597
• 负责人: Anne Elizabeth West
• 金额: $ 44.06万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-05-01 至 2022-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9333597
• 关键词: ARHGEF5 gene; Address; Adult; Autistic Disorder; Biological Models; Brain; Cells; Cerebellum; ChIP-seq; Chromatin; Chromatin Structure; Clustered Regularly Interspaced Short Palindromic Repeats; Cues; Cytoplasmic Granules; Data; Development; Distal; Enhancers; Enzymes; Event; Foundations; Gene Activation; Gene Expression; Genes; Genetic Transcription; Genomic DNA; Genomics; Goals; Histone H3; Histones; Impairment; Intellectual functioning disability; Kinetics; Knock-out; Lysine; Mediating; Methods; Modification; Molecular; Mus; Mutation; Neurodevelopmental Disorder; Neuronal Differentiation; Neurons; Phase; Phosphorylation; Play; Population; Process; Proteins; Recruitment Activity; Regulation; Regulator Genes; Regulatory Element; Repression; Role; Sensory; Synapses; Testing; Time; Transcriptional Activation; Transcriptional Regulation; Variant; base; cell type; critical period; demethylation; derepression; epigenetic regulation; experimental study; gene induction; gene product; histone methyltransferase; in vivo; insight; knock-down; mRNA Expression; mouse model; neuronal circuitry; postnatal; programs; promoter; relating to nervous system; selective expression; synaptic function

Neuronal differentiation requires the precise orchestration of gene expression programs. Temporal control of transcription is particularly important in maturing postmitotic neurons of the postnatal brain because these cells need to express gene products that refine neuronal function and circuitry during specific critical periods of brain development. Epigenetic regulation of chromatin structure is known to play a role in establishing cell-type specific programs of gene expression during early stages of cell fate determination, but the chromatin mechanisms that regulate gene expression during terminal phases of differentiation remain to be fully understood. The goal of this proposal is to identify chromatin mechanisms that coordinate the induction of genes in maturing neurons of the CNS. To discover these chromatin mechanisms of neuronal differentiation, and to determine how these mechanisms are regulated across multiple stages of neuronal maturation, we have characterized chromatin accessibility, enhancer activation, and gene expression in differentiating cerebellar granule neurons (CGNs) of the postnatal mouse in vivo. We have observed that thousands of regulatory elements show chromatin accessibility changes as CGNs differentiate, and we have verified that many of these differentially accessible regions function as developmental stage-specific enhancers of neuronal genes. Furthermore our data identify a specific group of the genes selectively expressed in mature CGNs of the cerebellum that are associated with repressive histone H3 lysine 27 trimethylation (H3K27me3) at early postmitotic stages of CGN differentiation yet lose this mark as CGNs mature. Consistent with a role for active histone demethylation in the induction of these genes, we find that at least a subset of these genes show increased H3K27me3 and reduced mRNA expression in CGNs lacking the H3K27 demethylase Kdm6b. The overarching hypothesis of this proposal is that the molecular regulators of H3K27me3 dynamics in postmitotic neurons play a key role in timing neuronal maturation. To address this hypothesis we propose the following Specific Aims: 1) To characterize the dynamic demethylation of H3K27 in postmitotic neurons maturing in vivo, 2) To determine the role of the H3K27 demethylase Kdm6b in neuronal maturation, and 3) To identify enhancer mechanisms of transcriptional derepression in maturing neurons. Together these studies will identify the molecular mechanisms that mediate the gene-specific loss of H3K27me3 in maturing CGNs, and they will directly test the importance of the developmental derepression of H3K27me3-silenced genes for functional neuronal maturation.

神经元分化需要基因表达程序的精确编排。时间控制 转录在成熟的产后大脑的有丝分裂后神经元中尤其重要，因为这些细胞 需要表达在大脑特定关键时期内提高神经元功能和电路的基因产物 发展。已知染色质结构的表观遗传调节在建立细胞类型中起作用 在细胞命运测定的早期阶段，基因表达的特定程序，但是染色质 调节基因表达在分化末端相期间基因表达的机制仍然是完全的 理解。该提案的目的是确定染色质机制，以协调诱导的诱导 中枢神经系统成熟神经元中的基因。为了发现这些神经元分化的染色质机制， 并确定如何在神经元成熟的多个阶段调节这些机制，我们 已经表征了染色质的可及性，增强子的激活和基因表达 体内产后小鼠的小脑颗粒神经元（CGNS）。我们观察到成千上万 调节元素显示CGN分化时染色质的可及性的变化，我们已经证实了这一点 这些差异可访问的区域中有许多是神经元的发育阶段特异性增强子 基因。此外，我们的数据确定了在成熟的CGN中选择性表达的一组特定基因 与抑制性组蛋白H3赖氨酸27三甲基化（H3K27me3）相关的小脑 CGN分化的有丝分裂后阶段，但随着CGN的成熟而失去了这一标记。与主动角色一致 组蛋白脱甲基在这些基因的诱导中，我们发现这些基因的至少一个子集显示 H3K27me3增加并降低缺乏H3K27脱甲基酶KDM6B的CGN中的mRNA表达。这 该提议的总体假设是H3K27me3动力学的分子调节剂 有丝分裂后神经元在定时神经元成熟中起关键作用。为了解决这一假设，我们提出了 以下具体目的：1）表征有丝分裂后神经元中H3K27的动态脱甲基化 在体内成熟，2）确定H3K27脱甲基酶KDM6B在神经元成熟中的作用，而3） 确定成熟神经元中转录消除的增强机制。这些研究将共同 确定介导成熟CGN中H3K27me3基因特异性损失的分子机制，并且 他们将直接测试H3K27ME3脱毛基因的发育压缩的重要性 功能性神经元成熟。