Posttranscriptional control of meristem development

描述(申请人提供)：茎顶端分生组织是生于枝条顶端的细胞簇，其中含有少量的“干细胞”，作为生长和发育新细胞的来源。ArgAerte(AGO)家族蛋白参与多种生物的干细胞功能，包括果蝇和拟南芥。拟南芥的针头和ArgAerte基因是维持顶端分生组织的活性所必需的相关基因。PNH/AGO活性降低导致顶端分生组织被顶生叶所取代。相反，异位针头会导致额外的生长。AGO基因家族的成员似乎参与了各种RNA介导的过程。它们的特异性被认为是通过涉及microRNAs(长度约22bp的小RNAs)的机制来调节的。我们已经确定了两个与顶端发育有关的基因，它们的翻译可能受到PNH/AGO的调控，并将进行实验，以了解PNH/AGO调控这些基因翻译的机制。我们将通过将DNA芯片分析应用于多聚体图谱来识别PNH/AGO控制的其他靶点。我们将通过我们开发的抑制子/增强子筛选来识别PNH/AGO遗传途径的其他成分。我们还将探索显性PHB突变破坏调控miRNA结合的可能性。显性PHB突变导致PHB基因的异位基因积累增加和甲基化减少(顺式)。我们将尝试确定负责调节PHB的AGO样基因。最后，我们将进行实验，以确定PNH和AGO功能相互之间的不同程度，以及哪些基因或蛋白质序列对这种特异性负责。

DESCRIPTION (provided by applicant): Shoot apical meristems are clusters of cells borne at the tips of branches that contain a small number of "stem cells" that act as the source of new cells for growth and development. The ARGONAUTE (AGO) family of proteins is involved in stem cell function in organisms as diverse as Drosophila and Arabidopsis.The Arabidopsis PINHEAD and ARGONAUTE genes are related genes whose activity is required for maintenance of the shoot apical meristem. Lowering of PNH/AGO activity results in the shoot apical meristem being replaced by a terminal leaf. Conversely, ectopic PINHEAD leads to extra growth. Members of the AGO gene family appear to be involved in a variety of RNA-mediated processes. Their specificity is thought to be mediated through a mechanism involving microRNAs (small RNAs about 22 bp in length). We have identified two genes involved in development at the shoot apex whose translation is likely regulated by PNH/AGO and will carry out experiments to understand the mechanism by which PNH/AGO regulate the translation of these genes. We will identify additional targets of PNH/AGO control by applying DNA chip analysis to polysome profiles. We will identify other components of the PNH/AGO genetic pathway through a suppressor/enhancer screen we have developed. We will also explore the possibility that dominant PHB mutations disrupt binding of a regulatory miRNA. Dominant PHB mutations cause increased and ectopic mRNA accumulation and decreased methylation (in cis) of the PHB gene. We will attempt to identify the AGO-like gene responsible for regulating PHB. Finally, we will perform experiments to determine to what degree PNH and AGO functions differ from one another and what gene or protein sequences are responsible for this specificity.