Studies of P-glycoprotein and drug interactions

 描述（由申请方提供）：P-糖蛋白（Pgp）是一种高度动态的ATP结合盒（ABC）膜转运蛋白，可将多种分子流出细胞。它是药物在肠、肝、肾和脑中吸收、分布和排泄的主要决定因素，也是某些癌症、HIV和中枢神经系统（CNS）疾病中成功化疗的障碍。据估计，大约一半的上市药物是Pgp的转运底物或抑制剂，候选药物的Pgp敏感性评价已成为制药行业开发新疗法的重要步骤。然而，Pgp结合分子表现出复杂的活性，充当ATP酶刺激剂、抑制剂、转运底物或非转运配体。尽管进行了广泛的研究，我们仍然有非常有限的了解复杂的和多特异性的Pgp-药物相互作用有关的Pgp的运输，抑制和逃避的机制。本研究旨在（1）确定配体的结构和化学性质如何影响其与Pgp的相互作用，（2）表征Pgp如何在不同类别的配体结合后发生反应，以及（3）合理化化学合成以修饰现有药物以逃避Pgp转运。我们将使用综合化学，结构和功能的方法来解决这些目标，这是基于文献中的几个主要进展，我们最近取得了Pgp结构测定和配体相互作用。首先，我们建议进行一个全面的结构-活性关系的研究，在一个集中的图书馆配体轴承共同的支架。我们将使用一系列功能测定，包括ATP酶活性，详细的药物结合和竞争，基于细胞的运输和耐药性测定，以及结构表征来评估这些化合物。其次，我们将使用几种互补的生物物理技术，包括X射线晶体学，单粒子电子显微镜（EM），和亮度共振能量转移（LRET），用于确定Pgp/配体复合物的结构，构象分布和构象变化的动力学。通过EM和LRET表征Pgp构象，以及筛选新的配体、洗涤剂和脂质，以及稳定Pgp（和某些构象）的新结构，将促进更高分辨率（< 3.0 μ m）的结构研究，这是迄今为止Pgp尚未解决的关键障碍。第三，我们将修改几个Pgp药物底物的位置，已确定没有减少药物的效力，因此，重点是在Pgp相互作用的变化。通过相关的三个目标的研究，我们将实现一个详细的和基本的了解多特异性Pgp-药物相互作用，这将有深远的影响，药物发现鉴于Pgp的药理学和临床意义，许多现有的和研究药物是敏感的Pgp外排。

 DESCRIPTION (provided by applicant): P-glycoprotein (Pgp) is a highly dynamic ATP-binding cassette (ABC) membrane transporter that effluxes a diversity of molecules out of cells. It is a major determinant of drug absorption, distribution, and excretion in intestines, liver, kidney and brain, and also an impediment to successful chemotherapy in some cancers, HIV and central nervous system (CNS) diseases. About half of marketed drugs are estimated to be transport substrates or inhibitors of Pgp, and the evaluation of Pgp susceptibility of drug candidates has become an important step in the development of new therapeutics in the pharmaceutical industry. However, Pgp binding molecules exhibit complex activities, acting as ATPase stimulators, inhibitors, transport substrates, or non- transportable ligands. Despite extensive studies, we still have very limited understanding of the mechanisms for the complex and polyspecific Pgp-drug interactions pertaining to Pgp transport, inhibition and evasion. This study aims to (1) define how structural and chemical properties of a ligand affect its interactions with Pgp, (2) characterize how Pgp reacts upon the binding of different classes of ligands, and (3) rationalize chemical synthesis to modify existing drugs to evade Pgp transport. We will use an integrative chemistry, structural and functional approach to tackle these aims, which is based on several major advances in the literature and that we have most recently made on Pgp structural determination and ligand interactions. First, we propose to conduct a thorough structure-activity relationship study within a focused library of ligands bearing common scaffolds. We will use a battery of functional assays, including ATPase activity, detailed drug binding and competition, cell-based transport, and drug resistance assays, as well as structural characterizations to evaluate these compounds. Second, we will use several complementary biophysical techniques, including X- ray crystallography, single particle electron microscopy (EM), and luminance resonance energy transfer (LRET), for the determination of Pgp/ligand complex structures, conformational distributions, and the kinetics of conformational changes. The characterization of Pgp conformations by EM and LRET, together with the screen of novel ligands, detergents and lipids, as well as new constructs to stabilize Pgp (and certain conformations), will facilitate higher resolution (< 3.0 Å) structural studies, a critical barrier that has eluded Pgp thus far. Third, we will modify several Pgp drug substrates on positions that have been identified without diminution of drug potency, thus with a focus on resulting changes in Pgp interactions. By the related three aim studies we will achieve a detailed and fundamental understanding of polyspecific Pgp-drug interactions, which will have a far- reaching impact on drug discovery given the pharmacological and clinical significance of Pgp and that many current and investigational drugs are susceptible to Pgp efflux.