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

描述(申请人提供)：microRNA(MiR)调节和蛋白质破坏是细胞网络时空调节中的两个共同主题。这些转录后机制微调蛋白质在细胞内的作用，并在真核生物的多种过程中发挥重要作用，包括致癌信号、细胞周期调节、昼夜节律、病原体反应和细胞规格。MiR和泛素-蛋白酶体机制在真核生物之间都是高度保守的，它们在植物中的研究比其他模型系统有一些显著的优势。例如，植物miRs针对独特的、容易识别的mRNAs，将间接影响的可能性降至最低。这与后生生物系统形成鲜明对比，在该系统中，miR目标预测仍然困难。植物的F-box蛋白的数量也大大增加，F-box蛋白是控制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加工专门化。由于F-box蛋白的特异性还不是很清楚，在模式植物拟南芥中的研究提供了一个独特的机会来研究准确的底物靶向是如何发生的。本建议重点研究拟南芥ULO(异常侧方器官)蛋白的功能和调控，该蛋白是一个包含F-box蛋白的Kelch结构域，由两个miRs(miR394a/b)转录后调节。具体地说，该项目的目的是(1)确定ULO特异的蛋白质降解复合体(ES)的组成，(2)研究ULO的转录和转录后调控，以及(3)确定ULO对器官发生的贡献。这些目标将通过使用生物化学、蛋白质组学、遗传学和微皮肤来实现。ULO为研究高度保守的miR和蛋白酶体介导的调控机制之间的相互作用提供了一个独特的机会，在遗传上易驯化的多细胞生物体中。 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)，这是一种关键的模式生物，也是油菜、西兰花和番木瓜等多种作物的近亲。目的是确定一种名为异常侧翼器官(ULO)的蛋白质在胚胎、叶片和花形成过程中的器官模式中所起的作用。在包括人类在内的许多生物体中都发现了与Ulo相关的蛋白质，而这一大家族的蛋白质在人类疾病的许多方面都可以发挥重要作用，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.