Structural mechanism and function of endogenous ligands targeting orphan NR4A receptors

 描述(申请人提供)：核受体(NR)转录因子的NR4A亚类(Nurr1、Nur77和NOR-1)在哺乳动物的许多方面的发育、调节和维持中起重要作用 生理学。NR4A在中枢神经系统(CNS)中尤其丰富，并发挥着关键作用 在大脑发育和维护方面。针对NR4A活性的治疗药物可能在 治疗帕金森氏症(困扰美国100万人)和精神分裂症(折磨3 美国有100万人)。NR4A在骨骼肌、脂肪、心血管、 肾和肝组织，包括炎症疾病组织中的异常表达，表明NR4A调节剂可用于治疗炎症、关节炎、癌症和代谢状况(营养不良) 爱滋病， 肥胖、糖尿病和心血管疾病)。然而，探索配基和毒品的努力- 由于NR4A被归类为“孤儿”受体，它们的发育受到了严重的阻碍。 到目前为止，还没有发现内源性(天然的)NR4A配体，人们认为NR4A 独立于结合配体的功能。这种“孤儿”分类在一定程度上是基于一块水晶 ApoNurr1的结构，这表明Nurr1在非孤儿NRS用来结合内源配体的保守配体结合口袋区域缺乏物理空间。虽然apoNurr1晶体 结构显示了一个折叠的配体结合口袋，核磁共振研究表明这个区域是动态的 µS-毫秒时间刻度，暗示有扩展的能力。我们的初步工作使用了一系列结构和 功能研究表明，Nurr1可以在其可能的LBP中结合内源性配体，并且 内源性配体可以影响Nurr1的功能。我们的数据还表明，Nurr1和Nur77可能有 内源性配体的不同特异性。详细阐述了内切酶的结构机制和功能。 靶向NR4A的基因配体将证明这些孤儿受体确实是配体 调控并授权他人使用这些天然的化学工具来探索NR4A在体内的功能。我们提出了一种结合结构生物学和生化、生物物理和细胞分析的多学科方法来确定配体的特异性、结构和功能效应以及细胞 内源性配体靶向NR4A的结果。这些研究的结果将证明NR4A是骨配体结合受体。由于具有已知内源性配体的NRs是目前FDA批准的大量药物(2006年估计为13%)的靶标，这一知识将刺激针对帕金森氏症、精神分裂症和其他人类健康状况的NR4A药物靶向策略的开发。

 DESCRIPTION (provided by applicant): The NR4A subclass of nuclear receptor (NR) transcription factors (Nurr1, Nur77 and NOR-1) have essential roles in the development, regulation and maintenance of many aspects of mammalian physiology. NR4As are especially abundant in the central nervous system (CNS) and play critical roles in brain development and maintenance. Therapeutics targeting NR4A activity may hold utility in treatment of Parkinson's disease (afflicts 1 million people in the US) and schizophrenia (afflicts >3 million people in the US). The NR4As are also expressed in skeletal muscle, adipose, cardiovascular, kidney and liver tissues, including aberrant expression in inflamed disease tissues, suggesting utility forNR4A modulators to treat inflammation, arthritis, cancer, and metabolic conditions (dysli idemia, obesity, diabetes and cardiovascular disease). However, efforts to probe the ligandability and drugga- bility of the NR4As have been significantly stunted because they are classified as "orphan" receptors. Thus far, no endogenous (natural) NR4A ligands have been discovered, and it is believed the NR4As function independent of binding ligand. This "orphan" classification was made in part based on a crystal structure of apoNurr1, which indicates Nurr1 lacks physical space within the conserved ligand biding pocket region used by nonorphan NRs to bind endogenous ligands. Although the apoNurr1 crystal structure shows a collapsed ligandbinding pocket, NMR studies indicate this region is dynamic on the µs-ms timescale, suggesting the ability to expand. Our preliminary work using an array of structural and functional approaches shows that Nurr1 can bind an endogenous ligand in its putative LBP and that endogenous ligands can affect Nurr1 function. Our data also indicate that Nurr1 and Nur77 may have different specificities for endogenous ligands. Detailing the structural mechanism and function of endo- genous ligands targeting the NR4As will demonstrate these orphan receptors are indeed ligand regulated and empower others to use these natural chemical tools to explore NR4A function in vivo. We propose a multidisciplinary approach combining structural biology with biochemical, biophysical and cellular assays to determine the ligand specificity, structural and functional effects, and cellula outcomes of endogenous ligands targeting the NR4As. Outcomes from these studies would demonstrate that the NR4As are bone fide ligand-binding receptors. Because NRs with known endogenous ligands are targets of significant number of current FDA approved drugs (estimated at 13% in 2006), this knowledge will stimulate the development of NR4A drug targeting strategies for Parkinson's disease, schizophrenia, and other human health conditions.