Kimura Akatsuki, Onami Shuichi
Computational and Experimental Systems Biology Group, RIKEN Genomic Sciences Center, Tsurumi, Yokohama 230-0045, Japan.
J Cell Biol. 2007 Dec 31;179(7):1347-54. doi: 10.1083/jcb.200706005. Epub 2007 Dec 24.
Centrosome positioning is actively regulated by forces acting on microtubules radiating from the centrosomes. Two mechanisms, center-directed and polarized cortical pulling, are major contributors to the successive centering and posteriorly displacing migrations of the centrosomes in single-cell-stage Caenorhabditis elegans. In this study, we analyze the spatial distribution of the forces acting on the centrosomes to examine the mechanism that switches centrosomal migration from centering to displacing. We clarify the spatial distribution of the forces using image processing to measure the micrometer-scale movements of the centrosomes. The changes in distribution show that polarized cortical pulling functions during centering migration. The polarized cortical pulling force directed posteriorly is repressed predominantly in the lateral regions during centering migration and is derepressed during posteriorly displacing migration. Computer simulations show that this local repression of cortical pulling force is sufficient for switching between centering and displacing migration. Local regulation of cortical pulling might be a mechanism conserved for the precise temporal regulation of centrosomal dynamic positioning.
中心体定位受到作用于从中心体辐射出的微管上的力的积极调控。两种机制，即中心定向和极化皮质牵拉，是单细胞期秀丽隐杆线虫中心体连续居中及向后移位迁移的主要促成因素。在本研究中，我们分析作用于中心体的力的空间分布，以研究将中心体迁移从居中转换为移位的机制。我们利用图像处理来测量中心体的微米级运动，从而阐明力的空间分布。分布的变化表明，极化皮质牵拉在居中迁移过程中发挥作用。在居中迁移期间，向后定向的极化皮质牵拉主要在侧面区域受到抑制，而在向后移位迁移期间解除抑制。计算机模拟表明，皮质牵拉的这种局部抑制足以在居中迁移和移位迁移之间进行转换。皮质牵拉的局部调控可能是一种保守机制，用于精确的时间调控中心体的动态定位。
