摘要
贴壁细胞的形状和弹性(硬度)与细胞骨架网络的形态以及纤维的交联方式密切相关.而细胞骨架网络的形态和组成与细胞中的二型肌球蛋白的活动,尤其是肌球蛋白组装成的肌球蛋白粗丝(minifilament)的活动有关.细胞通过与其外部环境的机械传感(mechanosensing)来调节二型肌球蛋白的活动和肌球蛋白粗丝的相互作用,从而实现对细胞骨架网络重组(remodeling)的控制.当前对活体细胞内二型肌球蛋白的研究从实验测量到理论模型的建立之间还有不小距离,主要是因为直接测量会对细胞结构和生理活动产生影响,而间接测量不能得到肌球蛋白在细胞内活动的准确数据.因此本文提出利用新的免疫荧光显微图像分析技术,例如免疫荧光蛋白图像追踪和局部图像相关函数分析技术,分析He La细胞体内肌球蛋白在细胞骨架网络中的动态分布,总结出肌球蛋白主导的细胞骨架和张力纤维组装与分解过程中的基本动力学规律.图像分析结果说明:肌球蛋白纤维在细胞骨架网络构建过程中依次动态处于组装与分解状态,通过其粗丝相对旋转对齐与收缩产生张力以维持纤维束稳定,并形成有不同肌球蛋白和粘着斑数量与分布形态的三类稳定性肌动球蛋白网络,其稳定性和收缩力大小呈正相关、与所结合肌球蛋白数量密度成正比.
The morphology and elasticity of adhered cells is closely related to the structure of the cytoskeletal meshwork and the way that actomyosin fibers interact with each other to form the network, which is mediated by the activity of myosin Ⅱ Therefore the interaction between minifilaments （assembled by non-muscle myosinⅡ ） is important to the cell-level cytoskeletal remodeling through mechanosensing. However, at present it is still difficult to precisely obtain the experimental data of myosin Ⅱin vivo because the invasive measurement would disturb the cellular local structure and physiological activities, and the non-invasive measurement couldn＇t provide information about myosin Ⅱ activity accurately. In this paper, we developed and applied new images analysis methods, such as protein fluorescent image tracking and image correlation spectroscopy, to quantify the kinetics of disassembly and reassembly of actomyosin networks and compared them to studies by other groups. This analysis suggested the following processes contribute to the assembly of cortical actomyosin and stress fibers： random myosin mini-filament assembly and disassembly along the cortex; myosin mini-filament aligning and contraction; stabilization of cortical myosin upon increasing contractile tension. We found that the number of myosin I1 and focal adhesions are very important to the formation and stability of the type I, Ⅱ and Ⅱactomyosin network in HeLa cells, and the activity of myosin Ⅱ, which determines the dynamics of the actomyosin network reorganization, can be quantified through STICS （spatial temporal image correlation spectroscopy）. The formation of type I, Ⅱ, and Ⅱ actomyosin networks was explained through a mechanical model by adjusting the parameters of myosin Ⅱ activities and number density. The STICS method used in this study can be applied to evaluate the activity of other proteins in live cells.
出处
《生物化学与生物物理进展》
SCIE
CAS
CSCD
北大核心
2016年第3期244-255,共12页
Progress In Biochemistry and Biophysics
基金
国家自然科学基金(41501441
61572368)
中央高校基本科研业务费专项资金(410500028)资助项目~~
