Targeted Library Synthesis and Screening: Allosteric Modulators of Transporters

描述（由申请人提供）：发现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已经成为一种有希望的新方法，用于寻找比作为正构配体的药物具有显着治疗优势的药物。这种变构调节剂目前在g蛋白偶联受体领域正在深入探索。在中枢神经系统的膜结合靶点中，生物胺转运体，特别是多巴胺转运体，在兴奋剂滥用成瘾和许多精神疾病中起着关键作用。尽管作为DAT变构调节剂的配体已经引起了相当大的兴趣，但迄今为止，这种DAT变构调节剂的发现仍然难以捉摸。我们最近在一系列类似药物的小分子中发现了变构调节作用，这在寻找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，它们部分抑制了DAT结合、[3H]DA摄取和D-安非他明诱导的DA释放。此外，对这些化合物的一些类似物的评价揭示了同系物之间新出现的构效关系（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。我们的目标是探索这些初步线索，以确定具有更高效力的配体，并赋予其良好的物理化学性质，作为体外和体内工具，研究健康和疾病中DAT功能变构调节的生物学后果。我们在R21期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R33期体内研究的配体。SAR分析和QSAR模型开发将用于追求基于配体结构的方法，以合理设计新的重点库。选择的有希望的配体将对血清素转运体（SERT）和去甲肾上腺素转运体（NET）进行评估，以确定它们的转运靶选择性。我们的期望是，在两年的R21期结束时，我们将确定一组具有足够效力、疗效和选择性的化合物，以便在下一阶段进行进一步的研究。R33阶段的具体目标包括(a)针对一组靶标分析化合物，(b)确定系统生物利用度和脑渗透特性，以及(c)设计和合成放射性标签，作为表征新结合位点的工具。设想候选分子的体内研究包括(i)大鼠微透析实验（ii）大鼠运动研究（iii）确定化合物单独或与可卡因联合使用的效果(1)大鼠和猴子的辨别试验，(2)大鼠颅内自我刺激试验，(3)猴子的自我给药研究。这些研究揭示了DAT变构配体作为药物滥用和精神疾病治疗药物的潜力。

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.