Couturier Lydie, Mazouni Khalil, Bernard Fred, Besson Charlotte, Reynaud Elodie, Schweisguth François
Institut Pasteur, Department of Developmental and Stem Cell Biology, F-75015 Paris, France.
CNRS, UMR3738, F-75015 Paris, France.
Biol Open. 2017 Dec 15;6(12):1851-1860. doi: 10.1242/bio.026641.
In epithelia, mitotic cells round up and push against their neighbors to divide. Mitotic rounding results from increased assembly of F-actin and cortical recruitment of Myosin II, leading to increased cortical stability. Whether this process is developmentally regulated is not well known. Here, we examined the regulation of cortical stability in Sensory Organ Precursor cells (SOPs) in the pupal notum. SOPs differed in apical shape and actomyosin dynamics from their epidermal neighbors prior to division, and appeared to have a more rigid cortex at mitosis. We identified RhoGEF3 as an actin regulator expressed at higher levels in SOPs, and showed that RhoGEF3 had GTPase Exchange Factor (GEF) activity for Cdc42. Additionally, RhoGEF3 genetically interacted with both Cdc42 and Rac1 when overexpressed in the fly eye. Using a null mutation generated by CRISPR-mediated homologous recombination, we showed using live imaging that the gene, despite being dispensable for normal development, contributed to cortical stability in dividing SOPs. We therefore suggest that cortical stability is developmentally regulated in dividing SOPs of the fly notum.
在上皮细胞中，有丝分裂细胞会变圆并挤压相邻细胞以进行分裂。有丝分裂变圆是由F-肌动蛋白组装增加和肌球蛋白II皮层募集增加导致的，从而增强了皮层稳定性。这个过程是否受发育调控尚不清楚。在这里，我们研究了蛹期背板感觉器官前体细胞（SOPs）中皮层稳定性的调控。SOPs在分裂前顶端形状和肌动蛋白-肌球蛋白动力学与其表皮邻居不同，并且在有丝分裂时似乎具有更刚性的皮层。我们鉴定出RhoGEF3是一种在SOPs中表达水平较高的肌动蛋白调节剂，并表明RhoGEF3对Cdc42具有鸟苷酸交换因子（GEF）活性。此外，当在果蝇眼睛中过表达时，RhoGEF3与Cdc42和Rac1都发生遗传相互作用。使用CRISPR介导的同源重组产生的无效突变，我们通过实时成像表明，该基因尽管对正常发育不是必需的，但对分裂的SOPs中的皮层稳定性有贡献。因此，我们认为果蝇背板分裂的SOPs中的皮层稳定性受发育调控。
