SAS GENE FUNCTIONS AND CHROMATIN AND SILENCING

该项目的目标是了解 一个新发现的SAS基因家族 调节和基因组沉默。SAS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蛋白的功能是乙酰化关键的染色质成分。 SAS基因是在酵母中发现的，但序列 同源物，包括人类MOZ和Tip 60，具有重要意义 为了人类健康。MOZ是复发性8 p11中常见的5'端伴侣， 导致急性髓系白血病M4/M5亚型的易位 白血病Tip 60是与HIV-Tat相关的人类基因， 促进Tat依赖性转录水平的增加。 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相关疾病的了解 包括艾滋病和艾滋病相关的恶性肿瘤。酵母SAS分析 功能显示，SAS 2或SAS 3突变体在 转录沉默第三个酵母基因，ESA 1，是必需的， 生存能力由于ESA 1与人类同源物关系最密切， 该提案的大部分内容侧重于分析。条件等位基因， 包括假定的乙酰转移酶结构域中的突变， 确定ESA 1的关键区域。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ESA 1在单个或 细胞周期中的多个点，如果ESA 1功能丧失导致 沉默缺陷，从而潜在地识别遗传位点， 其抑制对于正常的有丝分裂生长是必需的。生化 表征将直接测试SAS基因 通过染色质乙酰化起作用。识别相关 底物和调节剂的活动将寻求通过 生物化学和遗传学方法。确定以下各项限值的试验 酵母和人类SAS基因之间的功能保守性将是 通过确定人类基因是否可以抑制酵母突变体 表型。将进行实验以检验以下假设： SAS活性的错误定位可能会导致疾病， 局部定义的转录调控模式。 结果 这些不同的实验方法应该建立机制， SAS基因的功能，并提出如何破坏这种功能导致 基因组沉默和激活的改变。

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.