Mechanisms of kinetic stabilization by the drugs paclitaxel and vinblastine.
Mechanisms of kinetic stabilization by the drugs paclitaxel and vinblastine.
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DOI：
10.1091/mbc.e16-08-0567
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发表时间：
2017-05-01
影响因子：
3.3
通讯作者：
Odde DJ
中科院分区：
文献类型：
--
作者：
Castle BT;McCubbin S;Prahl LS;Bernens JN;Sept D;Odde DJ
以微管动力学为靶点的化疗药物促进了动力学稳定的普遍表型。综合计算模型和荧光显微镜确定了导致动力学稳定的基本动力学和热力学机制，特别是通过药物紫杉醇和长春花碱。微管靶向剂(MTA)被广泛用作生物探针和化疗药物，直接与微管蛋白亚基结合，在动力学上稳定微管，抑制动态不稳定的特征自组装过程。然而，动力学稳定的分子水平机制尚不清楚，动力学不稳定及其被MTA消除的基本热力学和动力学要求尚未确定。在这里，我们将微管组装的计算模型与纳米尺度的荧光显微镜测量相结合，以确定组装促进剂MTAS紫杉醇和拆解促进剂长春花碱对动力学稳定的动力学和热力学基础。我们在活细胞中发现了两种不同的动力学稳定模式，一种是真正抑制长春花碱的开关动力学，另一种是紫杉醇的“伪”动力学稳定，几乎消除了GTP-和GDP-微管蛋白热力学状态之间的能量差异。通过任何一种机制，两种MTA的主要作用都是在没有坚固的GTP帽的情况下有效地稳定微管以防止解体。
Chemotherapeutic agents that target microtubule dynamics promote a universal phenotype of kinetic stabilization. Integrated computational modeling and fluorescence microscopy identify the fundamental kinetic and thermodynamic mechanisms that result in kinetic stabilization, specifically by the drugs paclitaxel and vinblastine. Microtubule-targeting agents (MTAs), widely used as biological probes and chemotherapeutic drugs, bind directly to tubulin subunits and “kinetically stabilize” microtubules, suppressing the characteristic self-assembly process of dynamic instability. However, the molecular-level mechanisms of kinetic stabilization are unclear, and the fundamental thermodynamic and kinetic requirements for dynamic instability and its elimination by MTAs have yet to be defined. Here we integrate a computational model for microtubule assembly with nanometer-scale fluorescence microscopy measurements to identify the kinetic and thermodynamic basis of kinetic stabilization by the MTAs paclitaxel, an assembly promoter, and vinblastine, a disassembly promoter. We identify two distinct modes of kinetic stabilization in live cells, one that truly suppresses on-off kinetics, characteristic of vinblastine, and the other a “pseudo” kinetic stabilization, characteristic of paclitaxel, that nearly eliminates the energy difference between the GTP- and GDP-tubulin thermodynamic states. By either mechanism, the main effect of both MTAs is to effectively stabilize the microtubule against disassembly in the absence of a robust GTP cap.