Characterization of a microRNA regulated F-box protein in Arabidopsis development

描述（由申请人提供）：微小RNA（miR）调控和蛋白质破坏是细胞网络时空调控中的两个常见主题。这些转录后机制微调细胞内的蛋白质作用，并在真核生物的多种过程中发挥重要作用，包括致癌信号，细胞周期调控，昼夜节律，病原体反应和细胞特化。miR和泛素-蛋白酶体机制在真核生物中高度保守，它们在植物中的研究与其他模式系统相比具有一些显著的优势。例如，植物miR靶向独特的、容易识别的mRNA，从而最大限度地减少间接影响的可能性。这与其中miR靶标预测仍然困难的后生动物系统形成对比。植物也有大量的F-box蛋白，这些分子控制着蛋白质降解的主要途径。这种扩增可能有助于增加这些蛋白质的细胞类型和过程专业化。由于F-box蛋白的特异性还没有很好地理解，在模式植物拟南芥中的研究提供了一个独特的机会，以检查如何准确的底物靶向发生。 本论文主要研究拟南芥ULO（UNUSUAL LATERAL ORGANS）蛋白的功能和调控。ULO蛋白是一种含有Kelch结构域的F-box蛋白，在转录后受到两个miR（miR 394 a/B）的调控。具体而言，本项目旨在（1）确定ULO特异性蛋白质降解复合物的组成，（2）检查ULO的转录和转录后控制，以及（3）确定ULO对器官发生的贡献。这些目标将通过采用生物化学，蛋白质组学，遗传学和显微镜来实现。ULO提供了一个独特的机会来研究在遗传上易处理的多细胞生物体中高度保守的miR和蛋白酶体介导的调控机制之间的相互作用。 公共卫生相关性：这项研究的重点是植物发育，并利用拟南芥（鼠耳水芹），这是一个关键的模式生物和许多作物物种，如油菜，花椰菜和木瓜的近亲。目的是确定一种蛋白质，不寻常的横向器官（ULO），在胚胎，叶和花形成期间的器官模式中的作用。ULO相关蛋白存在于包括人类在内的许多生物体中，这个蛋白质大家族在人类疾病的许多方面发挥重要作用，包括癌症和糖尿病。

DESCRIPTION (provided by applicant): MicroRNA (miR) regulation and protein destruction are two common themes in spatiotemporal regulation of cellular networks. These post-transcriptional mechanisms fine tune protein action within cells and play important roles in diverse processes among eukaryotes including oncogenic signaling, cell cycle regulation, circadian rhythms, pathogen response and cell specification. Both the miR and ubiquitin- proteasome machineries are highly conserved between eukaryotes, and their study in plants has some marked advantages over other model systems. For instance, plant miRs target unique, easily identifiable mRNAs, minimizing the possibility of indirect effects. This is in contrast to metozoan systems where miR target prediction is still difficult. Plants also have a greatly expanded number of F-box proteins, molecules controlling a major route of protein degradation. This expansion may have contributed to increased cell type and process specialization for these proteins. As the specificity of F-box proteins is not well understood, studies in the model plant Arabidopsis provide a unique opportunity to examine how accurate substrate targeting occurs. This proposal is focused on the function and regulation of the Arabidopsis ULO (UNUSUAL LATERAL ORGANS) protein, a Kelch domain containing F-box protein that is post-transcriptionally regulated by two miRs (miR394a/b). Specifically, this project aims to (1) determine the composition of ULO-specific protein degradation complex(es), (2) examine the transcriptional and post-transcriptional control of ULO, and (3) determine the contribution of ULO to organogenesis. These goals will be accomplished by employing biochemistry, proteomics, genetics, and microscropy. ULO provides a unique opportunity to study the interplay between the deeply conserved miR- and proteasome-mediated regulatory mechanisms in a genetically tractable, multicellular organism. PUBLIC HEALTH RELEVANCE: This research is focused on plant development and utilizes Arabidopsis thaliana (mouse-ear cress), which is a key model organism and a close relative of numerous crop species such as canola, broccoli and papaya. The goal is to determine the role of a protein, UNUSUAL LATERAL ORGANS (ULO), in organ patterning during embryo, leaf and flower formation. ULO-related proteins are found in many organisms, including humans, and this large family of proteins can play important roles in many aspect of human disease, including cancer and diabetes.