Posttranscriptional control of meristem development

描述（由申请人提供）：茎尖分生组织是枝尖上的细胞群，其中含有少量的“干细胞”，作为生长发育的新细胞的来源。ARGONAUTE （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PINHEAD基因和ARGONAUTE基因是维持茎尖分生组织所需的相关基因。PNH/AGO活性降低导致茎尖分生组织被顶叶取代。相反，异位的针头会导致额外的生长。AGO基因家族的成员似乎参与了多种rna介导的过程。它们的特异性被认为是通过一种涉及microRNAs（长度约为22 bp的小rna）的机制介导的。我们已经确定了两个参与茎尖发育的基因，它们的翻译可能受到PNH/AGO的调节，并将进行实验来了解PNH/AGO调节这些基因翻译的机制。我们将通过应用DNA芯片分析多聚体图谱来确定PNH/AGO控制的其他目标。我们将通过我们开发的抑制子/增强子筛选来确定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基因的甲基化（顺式）增加和异位积累和减少。我们将尝试鉴定负责调控PHB的ago样基因。最后，我们将进行实验，以确定PNH和AGO的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.