Targeted Library Synthesis and Screening: Allosteric Modulators of Transporters

描述(由申请人提供)：通过与生物靶标上的变构位点结合来调节受体功能的配体的发现，已经成为一种很有前途的新方法，用于寻找具有显著治疗优势的药物，而不是充当正构配体的药物。这类变构调节剂目前正在G蛋白偶联受体领域进行深入研究。在中枢神经系统的膜结合靶标中，生物胺转运体，尤其是多巴胺转运体(DAT)，在滥用兴奋剂成瘾和许多精神疾病中发挥着关键作用。尽管作为DAT的变构调节剂的配体已经引起了相当大的兴趣，但到目前为止，这种DAT的变构调节剂的发现仍然是难以捉摸的。我们最近发现了一系列类药物小分子之间的变构调节作用，这代表着在寻找DAT的变构配体方面取得了重大突破。对这些配体的研究表明，它们部分抑制DAT结合、[~3H]DA摄取和D-苯丙胺诱导的DA释放。此外，对这些化合物的几个类似物的评价揭示了同系物之间出现的构效关系(SAR)趋势，从而为进一步研究DAT功能的变构调节剂奠定了基础。我们的目标是寻求这些初步的线索，以确定具有更好的效力和良好的物理化学性质的配体，用于作为体外和体内工具来研究变构调节DAT功能对健康和疾病的生物学后果。我们在R21阶段的具体目标包括迭代设计、采购、合成和评估重点化合物文库，以快速确定一组适合在R33阶段进行体内研究的配体。将利用SAR分析和QSAR模型开发来寻求基于配体结构的方法，以合理设计新的重点文库。选择有希望的配体将与5-羟色胺转运体(SERT)和去甲肾上腺素转运体(NET)进行比较，以确定它们的转运体靶标选择性。我们的期望是，到两年的R21阶段结束时，我们将确定一组具有足够效力、有效性和选择性的化合物，以便在下一阶段进行进一步研究。R33阶段要实现的具体目标包括：(A)针对一组靶点分析化合物，(B)测定全身生物利用度和脑渗透特性，以及(C)设计和合成放射性标记，作为表征新结合部位的工具。设想的候选分子体内研究包括(I)大鼠的微透析实验(Ii)大鼠的运动研究和(Iii)化合物单独或与可卡因结合的效果的测定(1)大鼠和猴子的辨别试验，(2)大鼠的颅内自我刺激试验，以及(3)猴子的自我给药研究。这些研究应该揭示DAT的变构配体作为药物滥用和精神障碍的治疗药物的潜力。

DESCRIPTION (provided by applicant): Discovery of ligands that modulate receptor function by binding to allosteric sites on biological targets has emerged as a promising new approach for finding drugs possessing significant therapeutic advantages over drugs that act as orthosteric ligands. Such allosteric modulators are currently being explored in-depth in the field of G-protein-coupled receptors. Among the membrane bound targets in the central nervous system, the biogenic amine transporters in general, and the dopamine (DA) transporter (DAT) in particular, play a key role in addiction to stimulant drugs of abuse and in a number of psychiatric illnesses. Although ligands that are allosteric modulators of DAT have been of considerable interest, discovery of such allosteric modulators of DAT has hitherto remained elusive. Our recent discovery of allosteric modulatory effects among a series of drug-like small molecules represents a significant breakthrough in the search for allosteric ligands of DAT. Studies with these ligands have shown that they partially inhibit DAT binding, [3H]DA uptake, and D- amphetamine induced DA release. Moreover, evaluation of a few analogues of these compounds has revealed emerging structure-activity relationship (SAR) trends among the congeners, thus setting the stage for further research on allosteric modulators of DAT function. Our goals are to pursue these initial leads to identify ligands with improved potency and endowed with favorable physicochemical properties for their use as in vitro and in vivo tools to study the biological consequences of allosteric modulation of DAT function in health and disease. Our specific aims in the R21 phase include iterative design, procurement and synthesis and evaluation of focused libraries of compounds to rapidly identify a set of ligands suitable for in vivo studies in the R33 phase. SAR analysis and QSAR model development will be utilized to pursue ligand-structure based approaches for the rational design of new focused libraries. Selected promising ligands will be evaluated against serotonin transporter (SERT) and norepinephrine transporter (NET) to ascertain their transporter target selectivity. Our expectations are that by the end of the two year R21 phase we will have identified a select set of compounds with sufficient potency, efficacy and selectivity for further studies to be performed in the next phase. The specific aims to be pursued in the R33 phase include (a) profiling the compounds against a panel of targets, (b) determination of systemic bioavailability and brain penetration properties, and (c) design and synthesis of radiolabels to serve as tools for characterizing the novel binding site. Envisioned in vivo studies with candidate molecules include (i) microdialysis experiments in rats (ii) locomotor studies in rats and (iii) determination of the effects of the compounds alone or in combination with cocaine in (1) discrimination assays in rats and monkeys, (2) intracranial self-stimulation assays in rats, and (3) self-administration studies in monkeys. These studies should reveal the potential of the allosteric ligands of DAT as treatment agents for substance abuse and psychiatric disorders.