Molecular models to characterize actions of calcium sensitizing drugs

项目概要/摘要 心力衰竭是当今社会的一个紧迫问题。正性肌力药是需要在 治疗由于左心室收缩功能障碍引起的心力衰竭。目前使用的许多药物 (such作为β-肾上腺素能激动剂和磷酸二酯酶III抑制剂）长期无效 因为它们有严重的副作用钙增敏剂是一种有趣的替代品 候选药物，如果它们可以引起正性肌力作用而没有相关的副作用。一 钙增敏药物的可能靶点是心肌肌钙蛋白（cTn），一种钙依赖性开关， 激活和失活肌丝，导致收缩和松弛。心肌肌钙蛋白 由三个亚基组成：cTnC、cTnI和cTnT。越来越多的常规计算方法， 用于研究cTn。然而，仍然迫切需要开发新颖且更精确的方法。 这些工具扩大了对控制心脏收缩的分子过程的理解， 靶向药物发现研究。该提案的主要目的是开发新的 预测和调节cTnC内钙致敏的计算方法。结果 从计算方法的进步将得到实验验证和实验 结果将推动进一步的方法改进。拟议的研究分为三个结构 主要阶段。我们将使用计算机辅助药物设计研究，以发现和实验验证新的 钙增敏剂（目标I），然后开发计算模型，以了解 cTn中的分子过程是观察到的敏化效应的基础，直接反馈给 实验（目标二和三）。方法开发工作将侧重于克服两个主要障碍 心肌细胞收缩的计算模型所面临的问题。首先，我们将开发新的 准确预测钙与cTnC结合亲和力的方法（Aim II）。基于强 根据初步数据，我们假设这需要可极化的力场，没有这些力场，Ca 2 + 结合在分子动力学（MD）模拟中没有被充分地建模并且被过度简化。 其次，我们将预测药物打开cTnC-cTnI界面的程度（Aim III）。基于 根据初步数据，我们的假设是，微秒MD模拟和新的方法， 需要确定药物结合构象中疏水片的开放程度。 从计算方法的进步的结果将得到实验验证和实验 结果将推动进一步的方法改进，并提高我们最初的药物发现命中率。

Project Summary / Abstract Heart failure is a pressing problem in today’s society. Positive inotropic agents are needed in the treatment of heart failure due to left ventricular systolic dysfunction. Many of the currently used drugs (such as β-adrenergic agonists and phosphodiesterase III inhibitors) are ineffective in the long-term since they are plagued with severe side effects. Calcium sensitizing agents are interesting alternative drug candidates if they can cause a positive inotropic effect without associated side effects. One possible target for calcium sensitizing drugs is cardiac troponin (cTn), a Ca2+-dependent switch, activating and deactivating the myofilament leading to contraction and relaxation. Cardiac cTn consists of three subunits: cTnC, cTnI and cTnT. Increasingly routine computational methods are used to study cTn. However, there remains a critical need for development of novel and more precise tools that expand understanding of molecular processes governing heart contraction in order to guide targeted drug discovery studies. The main objective of this proposal is to develop novel computational methods to predict and modulate calcium sensitization within cTnC. Results from computational method advances will be verified experimentally and the experimental results will drive additional method refinement. The proposed research is structured into three main stages. We will use computer-aided drug design studies to find and experimentally verify novel calcium sensitizing agents (Aim I) and then develop computational models to understand the molecular processes in cTn that underlie the observed sensitizing effect with direct feedback to experiments (Aims II and III). Method development work will focus on overcoming two main hurdles faced by current computational models of cardiomyocyte contraction. Firstly, we will develop new methodology to accurately predict calcium binding affinities to cTnC (Aim II). Based on strong preliminary data, we hypothesize that this requires polarizable force fields, without which Ca2+ binding is not adequately modeled and oversimplified in molecular dynamics (MD) simulations. Secondly, we will predict the degree to which drugs open up the cTnC-cTnI interface (Aim III). Based on preliminary data, our hypothesis is that microsecond MD simulations and new methodology are needed to determine the opening degree of the hydrophobic patch in drug-bound conformations. Results from computational method advances will be verified experimentally and the experimental results will drive additional method refinement and improve our initial drug discovery hits.