SPECIFICITY OF HISTONE ACETYLTRANSFERASE ENZYMES FROM ARABIDOPSIS THALIANA

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 Pikaard实验室利用遗传学、生物化学和分子生物学技术研究基因被激活和抑制的方式。我们目前的研究项目集中在基因沉默和染色质蛋白和小RNA（siRNA）在这些表观遗传现象中发挥的作用。 本研究以植物为对象，其中拟南芥为重点。 非活性rRNA基因通过染色质修饰而沉默。rRNA基因沉默涉及DNA甲基化和组蛋白修饰的协同变化，我们提出了一个模型，其中DNA和组蛋白修饰在一个自我加强的循环途径中彼此上游。Pikaard小组希望确定参与这种抑制循环的染色质修饰活动，使用RNA干扰来敲低靶基因的表达。迄今为止，在筛选中已经鉴定了两种组蛋白去乙酰化酶、一种DNA甲基转移酶和几种甲基胞嘧啶结合蛋白。我们正在利用各种遗传学、细胞遗传学和生物化学方法来了解这些染色质修饰活动的作用机制，并了解它们的作用是如何交织在一起构成表观遗传开关的

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The Pikaard lab studies the ways genes are activated and repressed, using techniques of genetics, biochemistry and molecular biology. Our current research projects are focused on gene silencing and the role that chromatin proteins and small RNAs (siRNAs) play in these epigenetic phenomena. the research focuses on plants, the important one for this project is Arabidopsis thaliana. Inactive rRNA genes are silenced via chromatin modifications. rRNA gene silencing involves concerted changes in both DNA methylation and histone modification and we have proposed a model whereby DNA and histone modifications are each upstream of one another in a self-reinforcing, circular pathway. The Pikaard group wishes to identify the chromatin modifying activities involved in this repression cycle, using RNA-interference to knock down the expression of targeted genes. Two histone deacetylases, one DNA methyltransferase and several methylcytosine binding proteins have been identified in the screens thus far. We are making use of a variety of genetic, cytogenetic and biochemical approaches in order to understand the mechanism(s) of action of these chromatin modifying activities and to understand how their actions are intertwined to comprise an epigenetic on-off switch