Posttranscriptional control of meristem development

描述（由申请人提供）：茎尖分生组织是生长在树枝顶端的细胞簇，含有少量“干细胞”，作为生长和发育的新细胞来源。ARGONATE（AGO）蛋白家族参与果蝇和拟南芥等多种生物体的干细胞功能，拟南芥的PINHEAD和ARGONATE基因是维持茎顶端分生组织所必需的相关基因。PNH/AGO活性降低导致茎顶端分生组织被顶生叶取代。相反，异位针头导致额外的增长。AGO基因家族的成员似乎参与多种RNA介导的过程。它们的特异性被认为是通过涉及microRNA（长度约22 bp的小RNA）的机制介导的。我们已经确定了两个基因参与发展的茎尖，其翻译可能是由PNH/AGO调节，并将进行实验，以了解PNH/AGO调节这些基因的翻译的机制。我们将通过DNA芯片分析多核糖体谱来确定PNH/AGO控制的其他靶点。我们将通过我们开发的抑制/增强筛选来鉴定PNH/AGO遗传途径的其他组分。我们还将探讨显性的PHB突变破坏调节性miRNA结合的可能性。显性的PHB突变导致增加和异位的mRNA积累和减少甲基化（顺式）的PHB基因。我们将试图确定AGO样基因负责调节聚羟基丁酸酯。最后，我们将进行实验，以确定PNH和AGO功能在多大程度上彼此不同，以及哪些基因或蛋白质序列负责这种特异性。

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.