A continuum model of protrusion of pseudopod in leukocytes.
A continuum model of protrusion of pseudopod in leukocytes.
复制标题
白细胞中伪足突出的连续体模型。
DOI：
10.1016/s0006-3495(88)83047-9
复制
发表时间：
1988
影响因子：
3.4
通讯作者：
Skalak,R
中科院分区：
文献类型：
--
作者：
Zhu,C;Skalak,R
利用人白细胞的形态学、肌动蛋白聚合的生物化学和连续介质力学理论，模拟了白细胞的伪足伸出过程。在该模型中，伪足被认为是一个多孔固体的F-肌动蛋白网络，其孔隙充满了水溶液。G-肌动蛋白被认为是一种“溶质”，在流体相中通过对流和扩散进行运输。伪足生长为肌动蛋白丝在伪足尖端的倒刺末端伸长。延伸的驱动力被假设为由肌动蛋白聚合提供。据推测，肌动蛋白丝的伸长，由聚合反应释放的化学能提供动力，对膜上的反向压力做机械功。这也引起了在伪足尖端的流体相的压降，这是由肌动蛋白聚合所做的功与局部压力状态相关的方程来表示的。沿着伪足的压力梯度根据达西定律驱动流体过滤通过多孔伪足，这又将更多的肌动蛋白单体带到生长尖端。主细胞体作为G-肌动蛋白的储存库。采用修正的一级动力学方程描述聚合反应动力学。伪足的生长速率受调节蛋白的调节。构造了一个基于该机制的一维移动边界问题，并得到了近似解。与实验数据的比较表明，该模型与现有的观察是兼容的。该模型也适用于其他细胞系统的生长，如精子顶体突起的延长。
The morphology of human leukocytes, the biochemistry of actin polymerization, and the theory of continuum mechanics are used to model the pseudopod protrusion process of leukocytes. In the proposed model, the pseudopod is considered as a porous solid of F-actin network, the pores of which are full of aqueous solution. G-actin is considered as a "solute" transported by convection and diffusion in the fluid phase. The pseudopod grows as actin filaments elongate at their barbed ends at the tip of the pseudopod. The driving force of extension is hypothesized as being provided by the actin polymerization. It is assumed that elongation of actin filaments, powered by chemical energy liberated from the polymerization reaction, does mechanical work against opposing pressure on the membrane. This also gives rise to a pressure drop in the fluid phase at the tip of the pseudopod, which is formulated by an equation relating the work done by actin polymerization to the local state of pressure. The pressure gradient along the pseudopod drives the fluid filtration through the porous pseudopod according to Darcy's Law, which in turn brings more actin monomers to the growing tip. The main cell body serves as a reservoir of G-actin. A modified first-order equation is used to describe the kinetics of polymerization. The rate of pseudopod growth is modulated by regulatory proteins. A one-dimensional moving boundary problem based on the proposed mechanism has been constructed and approximate solutions have been obtained. Comparison of the solutions with experimental data shows that the model is compatible with available observations. The model is also applicable to growth of other cellular systems such as elongation of acrosomal process in sperm cells.