Role of Set2 and H3 methylation in chromatin function

描述(由申请人提供)：组蛋白甲基化在染色质的组织和基因转录调控中起着重要作用。我们的长期目标是阐明赖氨酸特异性的组蛋白甲基转移酶如何调节基因表达，并促进细胞发育和疾病。在真核生物中高度保守的一种这样的酶是组蛋白H3赖氨酸36(H3K36)甲基转移酶Set2。我们和其他人已经证明，Set2在转录延伸过程中与RNA聚合酶II结合，并且它在H3K36的甲基化指导组蛋白脱乙酰酶复合体(Rpd3S)的招募，从而抑制不适当的转录起始。虽然Set2的基本功能已经确定，但关于以下几个方面仍然知之甚少：i)Set2酶本身是如何调节的，ii)该酶是否存在其他功能，以及iii)H3K36不同的甲基化状态(ME1、Me2和ME3)及其去甲基化如何促进染色质组织和基因转录。以酿酒酵母为模式生物，我们计划利用生物化学和遗传学的结合来进一步研究Set2和H3K36me在转录调控和其他方面的功能。我们的目标将是解决一些广泛的问题，这些问题将促进我们对组蛋白甲基转移酶和去甲基酶如何调节染色质环境和促进基因表达的理解。这些问题包括：1)Set2如何靶向基因并受翻译后修饰的调节？2)H3K36去甲基化如何促进转录过程？3)不同的H3K36甲基化状态在转录中是否具有不同的生物学活性，以及这个组蛋白‘标记’是否在DNA修复和复制等其他DNA相关活动中发挥作用？这些研究将对该领域产生重大影响，因为我们目前对组蛋白翻译后修饰，特别是H3K36甲基化的了解非常有限。介导H3K36甲基化的酶的失调会导致包括癌症在内的各种人类疾病，这一事实突显了这一点。鉴于哺乳动物细胞中具有多个H3K36甲基化酶的复杂性，酵母具有非凡的能力，可以应用遗传学和生物化学来了解染色质中一个非常重要的组蛋白“标记”的基本功能。 公共卫生相关性：染色质组织、DNA包装及其可及性方面的缺陷是导致人类疾病的主要原因，包括癌症和许多发育缺陷。我们对Set2的研究将揭示转录和修复等基于DNA的活动是如何受到调控的，这将解决这些公共卫生问题的根本原因。

DESCRIPTION (provided by applicant): Histone methylation plays a fundamental role in the organization of chromatin and in the regulation of gene transcription. Our long-term goal is to elucidate how lysine-specific histone methyltransferases regulate gene expression and contribute to cellular development and disease. One such enzyme that is highly conserved in eukaryotes is the histone H3 lysine 36 (H3K36) methyltransferase Set2. We, and others, have shown that Set2 associates with RNA polymerase II during transcription elongation, and that its methylation at H3K36 directs the recruitment of a histone deacetylase complex (Rpd3S) that suppresses inappropriate initiation of transcription. While the basic functions of Set2 have been characterized, little is still known regarding: i) how the Set2 enzyme itself is regulated, ii) whether other functions for this enzyme exist, and iii) how the distinct methylation states of H3K36 (me1, me2, and me3) and their demethylation contribute to chromatin organization and gene transcription. Using Saccharomyces cerevisiae as a model organism, we plan to use a combination of biochemistry and genetics to further address the functions of Set2 and H3K36me in transcriptional regulation and beyond. Our goal will be to address a number of broad questions that will advance our understanding of how histone methyltransferases and demethylases regulate the chromatin environment and contribute to gene expression. These include: 1) How is Set2 targeted to genes and is itself regulated by post- translational modification? 2) How does H3K36 demethylation contribute to the transcription process? 3) Do the different H3K36 methylation states have distinct biological activities in transcription, and does this histone 'mark' function in other DNA- related activities such as DNA repair and replication? These studies will have a significant impact to the field, as our current understanding of histone post-translational modifications, including H3K36 methylation in particular, is very limited. This is underscored by the fact that the dysregulation of enzymes that mediate H3K36 methylation lead to a variety of human diseases including cancer. Given the complexity of having multiple H3K36-methylating enzymes in mammalian cells, yeast affords the exceptional ability to apply genetics and biochemistry to understand the fundamental functions of a highly significant histone 'mark' in chromatin. PUBLIC HEALTH RELEVANCE: Defects in chromatin organization, DNA packaging and its accessibility is a major cause of human disease, including cancer and numerous developmental defects. Our studies on Set2 will reveal how DNA-based activities such as transcription and repair are regulated, which will address the underlying cause of these public health concerns.