Small Proteins and Renal Urea Transport Regulation

描述(由申请人提供)：尿素在尿液浓缩机制中起着关键作用，因此在水平衡的调节中起着关键作用。虽然第一个UT在1993年被克隆并取得了重大进展，但UT-A1在细胞中调控的分子机制仍然不清楚。我们最近发现了一些辅助蛋白，它们可能在UT-A1的成熟、运输、回收和降解中发挥关键调节作用。目前应用的总体目标是研究蛋白质-蛋白质相互作用如何调节细胞中的UT-A1活性。我们对一组小分子量蛋白质特别感兴趣，如小窝蛋白-1和14-3-3蛋白质。我们的初步数据表明，这些蛋白质可以物理上与UT-A1相互作用。我们选择这三个候选者是因为他们代表了三种蛋白质，它们在不同的步骤以不同的机制调节UT-A1。了解这些相互作用是解剖UT-A1细胞内转运、膜转运以及回收/降解过程的关键一步，这些过程都有助于在生理和病理条件下尿素在肾脏中的转运。我们的研究不仅将为我们理解UT-A1细胞调控(贩运、回收和降解)提供新的见解，也将为整个转运蛋白研究领域提供新的见解。我们的长期项目目标是与傅海安博士和埃默里化学生物学药物发现中心合作，筛选和开发这些蛋白(最初的14-3-3)在体内可能影响UT-A1功能的小分子调节剂，为高血压、充血性心力衰竭、肝硬变和肾病综合征等全身液体超载疾病提供潜在的治疗干预措施。

DESCRIPTION (provided by applicant): Urea plays a critical role in the urinary concentrating mechanism and therefore in the regulation of water balance. Although the first UT was cloned in 1993 and significant progress was achieved, the molecular mechanisms for UT-A1 regulation in cells are still unclear. We recently identified a number of accessory proteins which might play critical regulatory roles in UT-A1 maturation, trafficking, recycling and degradation. The overall goal of the current application is to investigate how the protein- protein interaction regulates UT-A1 activity in cells. We are particularly interested in a group of small molecular weight proteins, such as caveolin-1 and 14-3-3 proteins. Our preliminary data show that these proteins can physically interact with UT-A1. We choose these three candidates since they represent three kinds of proteins that regulate UT-A1 at different steps with different mechanisms. Understanding these interactions is a critical step in dissecting the processes of UT-A1 intracellular translocation, membrane trafficking, as well as retrieval/degradation that all contribute to the urea transport in kidney under physiological and pathological conditions. Our study will not only provide us new insights to understand UT-A1 cellular regulation (trafficking, recycling and degradation) but also provide new insights in the entire transporter research field. In collaboration with Dr. Haian Fu and the Emory Chemical Biology Drug Discovery Center, our long-term project aim is to screen and develop small-molecule modulators of these proteins (first 14- 3-3) that could affect UT-A1 function in vivo for potential therapeutic interventions for the diseases with total body fluid overload such as hypertension, congestive heart failure, cirrhosis, and nephrotic syndrome.