Ligand-Specific Allosteric Modulation by Drugs of Abuse

说明(申请人提供)：尽管作出了持续的努力，但仍缺乏对滥用物质的结构特性与其复杂的生理和行为表型之间的关系的详细了解。精神药物通常以神经细胞膜蛋白为靶点，这些蛋白通过复杂的变构机制被激活。通过这些机制，结构相似的配体可以在共同的蛋白质靶标上诱导出大量不同的生化和生物物理反应。例如，结合相同GPCR的配体可以调节非常不同的信号通路和下游细胞表型；这被称为“功能选择性”，已经在5-HT2A5-羟色胺受体上的滥用致幻药物和D2多巴胺受体上的各种抗精神病药物中观察到。另一类突触信号靶标，神经递质：钠转运体，也是精神刺激剂和抗抑郁药的靶标，每种底物诱导的门控和运输动力学非常不同。最近在生物物理实验(结晶学、单分子FRET)和计算方法(大规模分子动力学模拟和能量计算方法)方面的突破正在产生关于这些滥用药物的分子靶标和络合物的结构和动力学的详细分子信息。综上所述，这些结果表明，针对同一受体(或转运体)的不同药物引起的功能反应的多样性是配体特异性变构调节蛋白质的直接结果，使它们为差异偶联和 信号级联中的相互作用。在此基础上，我建议开发、实施并应用于我实验室研究的滥用药物靶标(5-HT2A和D2受体，以及亮氨酸样神经递质转运体，包括DAT和SERT)一系列新的计算方法，这些方法可以严格分析药物靶标的配体决定的反应。这些新的工具和方法将被用来实现对药物-靶点相互作用、功能选择性以及许多重要的抗精神病药物和滥用药物的作用机制的新视角和理解。我将开发这些技术，重点放在结构-功能关系上，这样结果就可以用一种允许实验探测的方式来表达，例如，通过突变、药理学图谱和结构技术的应用，如单分子FRET。我将提出新的可通过实验验证的假说，并与实验合作者一起设计旨在扩大对此类药物和药物机制的理解的新型实验。

DESCRIPTION (provided by applicant): Despite sustained efforts, a detailed understanding of the relation between structural properties of abused substances and their complex physiological and behavioral phenotypes, is still lacking. Psychotropic drugs often target neuronal membrane proteins that are functionally activated through complicated allosteric mechanisms. Through such mechanisms, structurally similar ligands can induce a large diversity of biochemical and biophysical responses on common protein targets. For example, ligands that bind the same GPCR can modulate very different signaling pathways and downstream cellular phenotypes; this is known as "functional selectivity" and has been observed for hallucinogenic drugs of abuse at the 5-HT2A serotonin receptor and for various antipsychotics at D2 dopamine receptors. Another class of synaptic signaling targets, the neurotransmitter:sodium symporters, are also targeted by psychostimulants and antidepressants, and each substrate induces very different gating and transport dynamics. Recent breakthroughs in biophysical experimentation (crystallography, single molecule FRET) and computational methodology (large scale molecular dynamics simulations and methods for energy calculations) are yielding detailed molecular information about the structures and dynamics of these molecular targets and complexes with drugs of abuse. Combined, these results indicate that the diversity of functional responses induced by different drugs targeting the same receptor (or transporter) is the direct result of ligand-specific allosteric modulation of the proteins, preparing them for differential coupling and interactions in the signaling cascade. On this basis, I propose to develop, implement, and apply to the targets of drugs of abuse studied in my laboratory (the 5-HT2A and D2 receptors, and the LeuT-like neurotranmitter transporters including DAT and SERT) a series of novel computational methods that can analyze rigorously the ligand-determined responses of the drug targets. The novel tools and approaches will be applied to achieve a new perspective and understanding of drug-target interactions, functional selectivity, and the mechanism of action of many important antipsychotics and drugs of abuse. I will develop these techniques with an emphasis on structure-function relationships so that results can be expressed in a manner that allows experimental probing, e.g., with mutagenesis, pharmacological profiling, and the application of structural techniques such as single molecule FRET. I will produce new experimentally testable hypotheses and work with experimental collaborators in the design of new types of experiments aimed at expanding the understanding the mechanisms of such drugs and medications.