肌动球蛋白收缩性旋转细胞核
Actomyosin contractility rotates the cell nucleus
摘要：
真核细胞的细胞核在活跃的细胞骨架细丝中发挥作用，但其对这些细丝所携带的应力的反应在很大程度上未被探索。我们在这里报告的结果的平移和旋转动力学的单个成纤维细胞的细胞核的研究，与细胞迁移的影响，通过电镀到纤连蛋白涂层的微制造模式抑制。使用相同面积但不同形状和/或纵横比的图案来研究细胞几何形状对动力学的影响。在圆形、正方形和等边三角形上，原子核进行持续的旋转运动，而在相同面积的高纵横比矩形上，它只来回运动。圆形和三角形分别表示最大和最小的角速度。我们表明，我们的观察可以理解，通过流体动力学的方法，在该方法中，核被视为一个高度粘性的夹杂物居住在一个较低的粘性流体的可定向丝赋予主动应力。通过引入低浓度的blebbistatin选择性地降低肌动蛋白收缩性，显著降低了细胞核角运动的速度和持续时间。肌动蛋白的延时成像揭示了细胞核周围的相关流体动力学流动，其轮廓和大小与我们的理论方法的结果一致。因此，连贯的细胞内流动和随之而来的核旋转似乎是一种普遍的性质，细胞必须通过特定的机制来平衡，以维持核内稳态。
英文摘要：
The nucleus of the eukaryotic cell functions amidst active cytoskeletal filaments, but its response to the stresses carried by these filaments is largely unexplored. We report here the results of studies of the translational and rotational dynamics of the nuclei of single fibroblast cells, with the effects of cell migration suppressed by plating onto fibronectin-coated micro-fabricated patterns. Patterns of the same area but different shapes and/or aspect ratio were used to study the effect of cell geometry on the dynamics. On circles, squares and equilateral triangles, the nucleus undergoes persistent rotational motion, while on high-aspect-ratio rectangles of the same area it moves only back and forth. The circle and the triangle showed respectively the largest and the smallest angular speed. We show that our observations can be understood through a hydrodynamic approach in which the nucleus is treated as a highly viscous inclusion residing in a less viscous fluid of orientable filaments endowed with active stresses. Lowering actin contractility selectively by introducing blebbistatin at low concentrations drastically reduced the speed and persistence time of the angular motion of the nucleus. Time-lapse imaging of actin revealed a correlated hydrodynamic flow around the nucleus, with profile and magnitude consistent with the results of our theoretical approach. Coherent intracellular flows and consequent nuclear rotation thus appear to be a generic property that cells must balance by specific mechanisms in order to maintain nuclear homeostasis.
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