SAS GENE FUNCTIONS AND CHROMATIN AND SILENCING

拟议项目的目标是了解 染色质介导转录中新发现的SAS基因家族 调控和基因组沉默。由SA共享的序列签名 已知具有乙酰转移酶活性的蛋白质和酶表明 SAS蛋白通过乙酰化关键的染色质成分发挥作用。 在酵母菌中发现了SAS基因，但序列 包括人类MoZ和Tip60在内的同源物具有重大意义 为了人类健康。MOZ是复发性8p11中常见的5‘伴侣 导致M4/M5亚型急性髓系白血病的易位 白血病。Tip60是一种与HIV-TAT相关的人类基因 促进依赖于TAT的转录水平的提高。 因此，了解SAS功能中最保守的元素可能会导致 增加对白血病和艾滋病毒相关疾病的认识 包括艾滋病和艾滋病相关的恶性肿瘤。酵母菌SAS的分析 功能显示SAS2或SAS3突变体在 转录沉默。第三种酵母菌基因esa1是 生存能力。因为ESA1与人类同源物关系最密切， 该提案的大部分内容都集中在其分析上。条件等位基因， 包括假定的乙酰转移酶区域的突变，将 确定ESA的关键区1.条件等位基因分析 将促进拟议的遗传和细胞生物学解剖 ESA 1。将确定是否需要在单个或 细胞周期中的多个点，如果ESA1功能的丧失导致 到沉默缺陷，从而潜在地识别遗传基因座 它的抑制对于正常的有丝分裂生长是必不可少的。生化 表征将直接检验SAS基因的假设 通过染色质乙酰化起作用。相关人员的识别 将通过寻找活动的底物和调节器 生物化学和遗传方法。确定限值的测试 酵母和人类SAS基因之间的功能保守将是 通过确定人类基因是否可以抑制酵母突变来实现 表型。我们将进行实验来检验这一假设 SAS活性的错误定位可能通过改变导致疾病 转录调控的局部定义模式。结果来自 这些不同的实验方法应该建立起 SAS基因的功能，并提示该功能的中断如何导致 基因组沉默和激活的变化。

The proposed project's goals are to understand the function of the newly identified SAS gene family in chromatin-mediated transcriptional regulation and genomic silencing. A sequence signature shared by Sas proteins and enzymes known to have acetyltransferase activity suggests that the Sas proteins function by acetylating key chromatin components. SAS genes were discovered in the yeast Saccharomyces, but sequence homologs including human MOZ and Tip60, have significant implications for human health. MOZ is the common 5' partner in recurrent 8p11 translocations that lead to the M4/M5 subtype of acute myeloid leukemia. Tip60 is a human gene associated with HIV-Tat that facilitates increased levels of Tat-dependent transcription. Understanding the most conserved elements of SAS function may thus lead to increased understanding of leukemia and HIV related disease including AIDS and AIDS-related malignancies. Analysis of yeast SAS function revealed that SAS2 or SAS3 mutants are defective in transcriptional silencing. The third yeast gene, ESA1, is essential for viability. Because ESA1 is most closely related to the human homologs, much of the proposal focuses on its analysis. Conditional alleles, including mutations in the putative acetyltransferase domain, will identify critical regions of ESA 1. Analysis of conditional alleles will facilitate the proposed genetic and cell biological dissection of ESA 1. It will be determined if ESA 1 is required at a single or multiple points in the cell cycle and if loss of ESA1 function leads to silencing defects, thereby potentially identifying genetic loci whose repression is essential for normal mitotic growth. Biochemical characterization will test directly the hypothesis that SAS genes function through chromatin acetylation. Identification of relevant substrates and regulators of activity will be sought through biochemical and genetic approaches. Tests to determine limits of functional conservation between yeast and human SAS genes will be performed by determining if human genes can suppress yeast mutant phenotypes. Experiments will be performed to test the hypothesis that mis-localization of SAS activity may lead to disease by altering locally defined patterns of transcriptional regulation. Results from these diverse experimental approaches should establish mechanisms of SAS gene function and suggest how disruption of this function leads to alterations in genomic silencing and activation.