Nano- to microscale dynamics of P-selectin detachment from leukocyte interfaces. I. Membrane separation from the cytoskeleton
Nano- to microscale dynamics of P-selectin detachment from leukocyte interfaces. I. Membrane separation from the cytoskeleton
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DOI：
10.1529/biophysj.104.051698
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发表时间：
2005-03-01
影响因子：
3.4
通讯作者：
Kinoshita, K
中科院分区：
文献类型：
--
作者：
Evans, E;Heinrich, V;Kinoshita, K
我们已经使用了一个生物膜力探针装饰与P-选择素形成点附件与PSGL-1受体对人中性粒细胞（PMN）在含钙介质中，然后量化的力所经历的附件在收缩过程中的PMN在固定的速度。从第一次接触到最终脱离，典型的力历史表现出以下事件顺序：i）PMN表面的初始线性弹性位移，ii）突然交叉到粘塑性流动，其标志着膜与内部细胞骨架分离和膜系链的开始，以及iii）通常通过P-选择素的一个陡峭步骤从探针尖端最终脱离：PSGL-1解离。在这第一篇文章我，我们专注于最初的弹性响应和终止膜分离的细胞骨架，启动系链形成。在240 pN/s至38，000 pN/s的弹性范围内，对加载速率（力/时间）下的膜松解力进行定量，我们发现力分布与弱键动力学有限失效理论吻合良好。发现膜解结合的动力学速率作为拉力的指数函数增加，其特征在于力的e倍尺度为17 pN，指前因子或表观无应力脱离速率类似于1/s。在配套文章II中介绍了系链生长后的膜解绑事件的流变特性。
We have used a biomembrane force probe decorated with P-selectin to form point attachments with PSGL-1 receptors on a human neutrophil (PMN) in a calcium-containing medium and then to quantify the forces experienced by the attachment during retraction of the PMN at fixed speed. From first touch to final detachment, the typical force history exhibited the following sequence of events: i), an initial linear-elastic displacement of the PMN surface, ii), an abrupt crossover to viscoplastic flow that signaled membrane separation from the interior cytoskeleton and the beginning of a membrane tether, and iii), the final detachment from the probe tip by usually one precipitous step of P-selectin: PSGL-1 dissociation. In this first article I, we focus on the initial elastic response and its termination by membrane separation from the cytoskeleton, initiating tether formation. Quantifying membrane unbinding forces for rates of loading ( force/time) in the elastic regime from 240 pN/s to 38,000 pN/s, we discovered that the force distributions agreed well with the theory for kinetically limited failure of a weak bond. The kinetic rate for membrane unbinding was found to increase as an exponential function of the pulling force, characterized by an e-fold scale in force of; 17 pN and a preexponential factor, or apparent unstressed off rate, of similar to1/s. The rheological properties of tether growth subsequent to the membrane unbinding events are presented in a companion article II.