Polarity and Morphogenesis Team, Institut Jacques Monod, CNRS UMR 7592, Université Paris-Diderot, Sorbonne sParis Cité, Paris Cedex 75205, France.
Polarity, Division and Morphogenesis Team, Institut Curie, CNRS UMR 3215, INSERM U934, 26 rue d'Ulm, Paris Cedex 05 75248, France.
Nat Commun. 2017 Apr 27;8:15168. doi: 10.1038/ncomms15168.
Controlling nucleus localization is crucial for a variety of cellular functions. In the Drosophila oocyte, nuclear asymmetric positioning is essential for the reorganization of the microtubule (MT) network that controls the polarized transport of axis determinants. A combination of quantitative three-dimensional live imaging and laser ablation-mediated force analysis reveal that nuclear positioning is ensured with an unexpected level of robustness. We show that the nucleus is pushed to the oocyte antero-dorsal cortex by MTs and that its migration can proceed through distinct tracks. Centrosome-associated MTs favour one migratory route. In addition, the MT-associated protein Mud/NuMA that is asymmetrically localized in an Asp-dependent manner at the nuclear envelope hemisphere where MT nucleation is higher promotes a separate route. Our results demonstrate that centrosomes do not provide an obligatory driving force for nuclear movement, but together with Mud, contribute to the mechanisms that ensure the robustness of asymmetric nuclear positioning.
控制核定位对于各种细胞功能至关重要。在果蝇卵母细胞中，核不对称定位对于微管（MT）网络的重组至关重要，该网络控制着轴决定因素的极化运输。定量三维活体成像和激光消融介导的力分析的结合表明，核定位具有出人意料的稳健性。我们表明，核被 MT 推向卵母细胞的前背皮质，并且其迁移可以通过不同的轨迹进行。中心体相关的 MT 有利于一条迁移途径。此外，MT 相关蛋白 Mud/NuMA 以依赖 Asp 的方式在核被膜的半球中不对称定位，该位置的 MT 成核率更高，从而促进了另一条途径。我们的结果表明，中心体不会为核运动提供必需的驱动力，但与 Mud 一起，有助于确保不对称核定位稳健性的机制。
