Genetic and Molecular Definition of Histone Modifying Enzyme Functions

了解组蛋白修饰是如何调节的， 了解正常和非正常细胞中的染色质组织和基因调控机制， 疾病状态。我们研究的总体目标是解决这个具有挑战性的问题，使用 遗传和分子方法来确定哪些组蛋白修饰酶，并通过扩展， 其中组蛋白修饰控制特定的基因表达程序， contexts.我们的工作主要集中在Gcn 5组蛋白乙酰转移酶（HAT）和Gcn 5组蛋白乙酰转移酶（HAT）上。 USP22组蛋白去泛素化酶（DUB），这两种酶都是一种大的多蛋白的组分 被称为佐贺。Gcn5、USP 22和其他佐贺组分涉及 人类疾病，包括癌症和神经变性，但分子机制 这些影响的根本原因尚不清楚。在过去的20年里，我们创造了一个新颖的工具包， Gcn 5和USP 22突变小鼠和细胞的基因组，包括无效等位基因、条件性（floxed）等位基因，以及 点突变等位基因（在Gcn5 HAT结构域、Gcn5布罗莫结构域或USP 22 DUB中 域），影响这些酶的活性。我们对Gcn 5突变的研究揭示了关键的 深入了解这种HAT在发育过程中的转录和非转录功能， 最近，他们揭示了Gcn 5和Myc功能之间的重要联系， 正常的干细胞和癌症。我们的USP22突变小鼠揭示，这种DUB也是至关重要的， 胚胎存活，但通过不同的途径比GCN 5损失的影响。尽管 尽管取得了这些进展，但仍然存在许多重大的知识空白。我们只能看到一部分 在哺乳动物细胞中哪些转录程序需要Gcn 5。此外，GCN 5现在已知 是第二个组蛋白修饰复合物ATAC的一部分，但我们不知道Gcn5是如何被激活的。 在这些复合物之间分配或它们在发育或疾病中的相对作用。我们也 对USP 22和佐贺DUB模块在特定环境中的作用不完全了解 组织，如小脑，这是特别相关的，因为特定的组成部分， 佐贺DUB模块与使人衰弱的神经退行性疾病，脊髓小脑 共济失调7型（SCA7）。这个MIRA将为我们提供稳定和灵活的资金，以继续我们的遗传， 生物化学和分子研究来解决这些至关重要的问题。从长远 因此，Gcn 5和USP 22正常功能的定义将为以下研究提供分子基础： 为这些因子被错误调节的疾病开发新的治疗选择。

Understanding how histone modifications are regulated is fundamentally important for understanding mechanisms of chromatin organization and gene regulation in both normal and disease states. The overall goal of our research is to address this challenging question, using genetic and molecular approaches to define which histone modifying enzymes, and by extension, which histone modifications, govern specific gene expression programs in particular biological contexts. Our work is focused largely on the Gcn5 histone acetyltransferase (HAT) and the USP22 histone deubiquitylase (DUB), which are both components of a large multiprotein assembly termed SAGA. Gcn5, USP22 and other SAGA components have been implicated in human maladies, including cancer and neurodegeneration, but the molecular mechanisms underlying such effects are not known. Over the past 20 years, we have created a novel toolkit of Gcn5 and USP22 mutant mice and cells, including null alleles, conditional (floxed) alleles, and point mutated alleles (in the Gcn5 HAT domain, the Gcn5 bromodomain, or the USP22 DUB domain) that affect the activity of these enzymes. Our studies of Gcn5 mutations revealed key insights to both transcriptional and non-transcriptional functions for this HAT during development, and most recently, they revealed important connections between Gcn5 and Myc functions both in normal stem cells and in cancer. Our USP22 mutant mice revealed that this DUB is also critical for embryo survival, but through different pathways than those affected by Gcn5 loss. Despite these advances, many significant gaps in knowledge still remain. We have only a partial view of which transcription programs require Gcn5 in mammalian cells. Moreover, Gcn5 is now known to be part of a second histone modifying complex called ATAC, but we do not know how Gcn5 is apportioned between these complexes or their relative roles in development or disease. We also have an incomplete understanding of the roles of USP22 and the SAGA DUB module in specific tissues such as the cerebellum, which is especially relevant since specific components of the SAGA DUB module are linked to a debilitating neurodegenerative disease, spinal cerebellar ataxia type 7 (SCA7). This MIRA will provide us stable and flexible funding to continue our genetic, biochemical, and molecular studies to address these critically important questions. In the longer term, definition of the normal functions of Gcn5 and USP22 will provide molecular foundations for development of new therapeutic options for diseases in which these factors are mis-regulated.