aDepartment of Mechanical Engineering and Maryland NanoCenter, University of Maryland, 2181 Glenn L. Martin Hall, College Park, MD 20742, USA
来源
2008-6-20 15:17:00
J. Biomech. :构建活细胞微管皱曲力学模型
细胞的力学性质很大程度上由细胞骨架决定，细胞骨架是由微管、中间丝和肌动蛋白丝这三种主要的蛋白丝构成的自组织网状结构。作为最坚硬的细胞骨架丝，在活细胞内微管承受压力，以平衡细胞骨架内的拉力来维系细胞形状。
实验室中经常发现在活细胞内，受压的微管皱曲为短波长的形状。与之相比较，孤立的体外微管则皱曲成单一的长波长弧形。体外微管的关键皱曲力要比活细胞条件下低两个数量级。为解释这个差别，马里兰大学学者Teng Li构建了一个活细胞的微管皱曲力学模型。运用该模型研究了周围细丝网状结构和胞质溶胶对微管皱曲的作用。研究结果显示，皱曲波长由微管和周围弹性细丝网状结构的共同作用决定，皱曲的增长率由粘性胞质溶胶决定。考虑皱曲的微管的非线性变形，皱曲振幅可以通过动力学约束方程决定。
这个模型通过微管的皱曲波长、增长率和振幅定量地把微管弯曲强度、周围细丝网状结构的弹性和胞质溶胶的粘性连接起来。模型所预测的短波长皱曲行为与实验结果吻合较好，这一结果为设计统一标准的实验仪器来测量活细胞条件下亚细胞结构的各种关键力学参数奠定了基础。
相关论文发表在爱思唯尔期刊《生物力学杂志》（Journal of Biomechanics）上。（科学新闻杂志 牛文鑫/编译）
生物谷推荐原始出处：
A mechanics model of microtubule buckling in living cells
Teng Li
, a, 
Accepted 5 March 2008.
Available online 22 April 2008.
Abstract
As the most rigid cytoskeletal filaments, microtubules bear compressive forces in living cells, balancing the tensile forces within the cytoskeleton to maintain the cell shape. It is often observed that, in living cells, microtubules under compression severely buckle into short wavelengths. By contrast, when compressed, isolated microtubules in vitro buckle into single long-wavelength arcs. The critical buckling force of the microtubules in vitro is two orders of magnitude lower than that of the microtubules in living cells. To explain this discrepancy, we describe a mechanics model of microtubule buckling in living cells. The model investigates the effect of the surrounding filament network and the cytosol on the microtubule buckling. The results show that, while the buckling wavelength is set by the interplay between the microtubules and the elastic surrounding filament network, the buckling growth rate is set by the viscous cytosol. By considering the nonlinear deformation of the buckled microtubule, the buckling amplitude can be determined at the kinetically constrained equilibrium. The model quantitatively correlates the microtubule bending rigidity, the surrounding filament network elasticity, and the cytosol viscosity with the buckling wavelength, the buckling growth rate, and the buckling amplitude of the microtubules. Such results shed light on designing a unified experimental protocol to measure various critical mechanical properties of subcellular structures in living cells.
Keywords: Microtubule; Buckling; Cytoskeleton; Mechanics modeling
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