Ligand-Specific Allosteric Modulation by Drugs of Abuse

描述（由申请人提供）：尽管持续的努力，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，仍然缺乏。精神药物通常靶向通过复杂的变构机制功能性激活的神经元膜蛋白。通过这样的机制，结构相似的配体可以诱导对共同蛋白质靶标的大量多样性的生物化学和生物物理响应。例如，结合相同GPCR的配体可以调节非常不同的信号传导途径和下游细胞表型;这被称为“功能选择性”，并且已经在5-HT 2A血清素受体上观察到致幻药物滥用，并且在D2多巴胺受体上观察到各种抗精神病药物。另一类突触信号靶点，神经递质：钠共转运体，也是精神兴奋剂和抗抑郁药的靶点，每种底物诱导非常不同的门控和转运动力学。最近在生物物理实验（晶体学，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）的突破正在产生详细的分子信息的结构和动力学这些分子靶标和复合物的滥用药物。结合起来，这些结果表明，由靶向相同受体（或转运蛋白）的不同药物诱导的功能反应的多样性是蛋白质的配体特异性变构调节的直接结果，使它们为差异偶联和结合做好准备。 信号级联中的相互作用。在此基础上，我建议开发，实施，并应用于在我的实验室研究的药物滥用的目标（5-HT 2A和D2受体，和LeuT样神经递质转运蛋白，包括DAT和SERT）一系列新的计算方法，可以严格分析配体确定的药物靶点的反应。新的工具和方法将被应用于实现一个新的角度和药物靶点相互作用，功能选择性，以及许多重要的抗精神病药物和药物滥用的作用机制的理解。我将开发这些技术，强调结构-功能关系，以便结果可以以允许实验探测的方式表达，例如，通过诱变、药理学分析和结构技术如单分子FRET的应用。我将提出新的实验可验证的假设，并与实验合作者一起设计新型实验，旨在扩大对此类药物和药物机制的理解。

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.