Role of MacroH2A in Estrogen-Regulated Gene Expression

描述（由申请人提供）：为了使雌激素受体（ER）激活基因转录，它必须克服抑制染色质结构。内质网通过招募启动子酶来完成这一过程，这些启动子酶要么共价修饰染色质，要么将其改造成更允许的状态。直到最近，人们才发现并非所有的染色质都是同质的。组蛋白变体取代了基因组特定区域的标准组蛋白对应物。组蛋白变异对基因调控的影响在很大程度上是未知的。然而，初步数据表明，组蛋白变体macroH2A参与乳腺癌细胞中er调控的转录。MacroH2A也与X失活期间发生的转录表观遗传沉默有关。最近，macroH2A与烟酰胺腺嘌呤二核苷酸（NAD+）代谢产物adp -核糖（ADPR）和o -乙酰基adp -核糖（OAADPR）结合。这一发现暗示了macroH2A是两个NAD+依赖途径中令人兴奋的信号事件的靶标：聚（adp -核糖）聚合酶（PARP）合成的聚（adp -核糖）（PAR）链被聚（adp -核糖）糖水解酶（PARC）的翻转和SIRT1对蛋白质的去乙酰化。这些研究的目的是为了更好地了解macroH2A在雌激素靶基因上结合的原因（目的1）和macroH2A在这些基因上结合的影响（目的2）。为此，将使用各种基于生化细胞和生物信息学的方法，包括染色质免疫沉淀（ChIP）， chlp芯片，表达分析，RNAi，蛋白质-蛋白质相互作用测定，酶测定和DMA基序查找算法。雌激素通过内质网传递信号，在性发育和生育等正常生理过程中发挥重要作用。然而，雌激素也会促进乳腺癌的生长和发展，并对心脏病、中风和骨质疏松症有保护作用。因此，了解macroH2A调控内质网靶基因转录的机制将有助于了解这些疾病的进展。

DESCRIPTION (provided by applicant): In order for estrogen receptor (ER) to activate gene transcription it must overcome a repressive chromatin structure. ER does this by recruiting to the promoter enzymes that either covalently modify chromatin or remodel it into a more permissive state. Only recently has it become apparent that all chromatin is not homogenous. Histone variants replace their canonical histone counterparts in specific regions of the genome. The effect of histone variants on gene regulation is largely unknown. However, preliminary data indicates that the histone variant macroH2A is involved in ER-regulated transcription in breast cancer cells. MacroH2A has also been implicated in the epigenetic silencing of transcription that occurs during X inactivation. Recently, macroH2A was shown to bind to the nicotinamide adenine dinucleotide (NAD+) metabolites ADP-ribose (ADPR) and O-acetyl-ADP-ribose (OAADPR). This finding implicates macroH2A as a target of exciting signaling events in two NAD+-dependent pathways: the turnover of poly(ADP-ribose) polymerase (PARP)-synthesized poly(ADP-ribose) (PAR) chains by poly(ADP-ribose) glycohydrolase (PARC) and deacetylation of proteins by SIRT1. The objective of these studies is to achieve a better understanding of both the causes of macroH2A incorporation at estrogen target genes (Aim 1) and effects of macroH2A incorporation at these genes (Aim 2). Toward this end, a variety of biochemical cell-based,and bioinformatic approaches will be used including Chromatin immunoprecipition (ChIP), ChlP-chip, expression analysis, RNAi, protein-protein interaction assays, enzyme assays, and DMA motif finding algorithms. Estrogen signaling through the ER plays important roles in normal physiological processes such as sexual development and fertility. However, estrogen also promotes the growth and progression of breast cancer and has a protective effect from heart disease, stroke and osteoporosis. Therefore, an understanding of the mechanism by which macroH2A regulates the transcription of ER target genes will provide insights into the progression of these diseases.