Clathrin regulates centrosome positioning by promoting acto-myosin cortical tension in C. elegans embryos
Clathrin regulates centrosome positioning by promoting acto-myosin cortical tension in C. elegans embryos
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DOI：
10.1242/dev.107508
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发表时间：
2014-07
期刊：
影响因子：
4.6
通讯作者：
Zoltán Spiró;K. Thyagarajan;A. De Simone;Sylvain Träger;K. Afshar;P. Gönczy
中科院分区：
文献类型：
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作者：
Zoltán Spiró;K. Thyagarajan;A. De Simone;Sylvain Träger;K. Afshar;P. Gönczy
中心体和纺锤体定位的调节对于空间细胞分裂控制至关重要。事实证明，单细胞秀丽隐杆线虫胚胎对于剖析后生动物中中心体和纺锤体定位的机制很有吸引力。先前的研究表明，这些过程依赖于位于细胞皮层的进化上保守的力发生器复合体。该复合物锚定了运动蛋白动力蛋白，从而允许对来自微管组织中心（MTOC）的星体微管施加皮质拉力。在这里，我们报道网格蛋白重链 CHC-1 负向调节单细胞秀丽隐杆线虫胚胎间期作用于中心体和有丝分裂期间作用于纺锤体极的拉力。我们建立了胞质分裂/细胞凋亡/RNA 结合蛋白 CAR-1 的类似作用，并发现需要 CAR-1 来维持适当的 CHC-1 水平。我们证明 CHC-1 对于皮质肌动球蛋白网络的正常组织和完整的皮质张力是必需的。此外，我们确定，CHC-1耗尽的胚胎的中心体定位表型通过稳定肌动球蛋白网络而得到缓解。相反，我们证明，在其他野生型胚胎中，肌动球蛋白网络的轻微扰动会导致类似于 chc-1(RNAi) 胚胎中的过度中心体运动。我们开发了一个二维计算模型来模拟皮质刚性相关的拉力，该模型概括了实验数据，并进一步证明了在中等皮质刚性值下会产生过度的中心体运动。总的来说，我们的研究结果使我们提出网格蛋白通过促进肌动球蛋白皮质张力在中心体定位中发挥关键作用。
Regulation of centrosome and spindle positioning is crucial for spatial cell division control. The one-cell Caenorhabditis elegans embryo has proven attractive for dissecting the mechanisms underlying centrosome and spindle positioning in a metazoan organism. Previous work revealed that these processes rely on an evolutionarily conserved force generator complex located at the cell cortex. This complex anchors the motor protein dynein, thus allowing cortical pulling forces to be exerted on astral microtubules emanating from microtubule organizing centers (MTOCs). Here, we report that the clathrin heavy chain CHC-1 negatively regulates pulling forces acting on centrosomes during interphase and on spindle poles during mitosis in one-cell C. elegans embryos. We establish a similar role for the cytokinesis/apoptosis/RNA-binding protein CAR-1 and uncover that CAR-1 is needed to maintain proper levels of CHC-1. We demonstrate that CHC-1 is necessary for normal organization of the cortical acto-myosin network and for full cortical tension. Furthermore, we establish that the centrosome positioning phenotype of embryos depleted of CHC-1 is alleviated by stabilizing the acto-myosin network. Conversely, we demonstrate that slight perturbations of the acto-myosin network in otherwise wild-type embryos results in excess centrosome movements resembling those in chc-1(RNAi) embryos. We developed a 2D computational model to simulate cortical rigidity-dependent pulling forces, which recapitulates the experimental data and further demonstrates that excess centrosome movements are produced at medium cortical rigidity values. Overall, our findings lead us to propose that clathrin plays a critical role in centrosome positioning by promoting acto-myosin cortical tension.