Cell Division and Neurogenesis, IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France; Sorbonne Universités, UPMC Université Paris 06, IFD, 4 Place Jussieu, 75252 Paris, France.
Laboratoire Physico-Chimie, Institut Curie, PSL Research University, CNRS, UPMC Université Paris 06, 75005 Paris, France.
Curr Biol. 2017 Aug 21;27(16):2452-2464.e8. doi: 10.1016/j.cub.2017.06.055. Epub 2017 Aug 10.
Oriented cell divisions are controlled by a conserved molecular cascade involving Gαi, LGN, and NuMA. We developed a new cellular model of oriented cell divisions combining micropatterning and localized recruitment of Gαi and performed an RNAi screen for regulators acting downstream of Gαi. Remarkably, this screen revealed a unique subset of dynein regulators as being essential for spindle orientation, shedding light on a core regulatory aspect of oriented divisions. We further analyze the involvement of one novel regulator, the actin-capping protein CAPZB. Mechanistically, we show that CAPZB controls spindle orientation independently of its classical role in the actin cytoskeleton by regulating the assembly, stability, and motor activity of the dynein/dynactin complex at the cell cortex, as well as the dynamics of mitotic microtubules. Finally, we show that CAPZB controls planar divisions in vivo in the developing neuroepithelium. This demonstrates the power of this in cellulo model of oriented cell divisions to uncover new genes required in spindle orientation in vertebrates.
定向细胞分裂由涉及 Gαi、LGN 和 NuMA 的保守分子级联控制。我们开发了一种新的定向细胞分裂的细胞模型，结合微图案化和 Gαi 的局部募集，并进行了 RNAi 筛选，以寻找 Gαi 下游的作用调节剂。值得注意的是，该筛选揭示了作为纺锤体定向所必需的独特的动力蛋白调节剂亚组，为定向分裂的核心调节方面提供了线索。我们进一步分析了一种新型调节剂，肌动蛋白加帽蛋白 CAPZB 的参与。从机制上讲，我们表明 CAPZB 通过调节细胞皮层处的动力蛋白/动力蛋白复合物的组装、稳定性和马达活性以及有丝分裂微管的动力学，独立于其在肌动蛋白细胞骨架中的经典作用来控制纺锤体定向。最后，我们表明 CAPZB 在发育中的神经上皮中控制体内的平面分裂。这证明了这种定向细胞分裂的细胞内模型在揭示脊椎动物纺锤体定向所需的新基因方面的强大功能。
