Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, NY 10029, USA.
Mol Biol Cell. 2011 Dec;22(23):4513-26. doi: 10.1091/mbc.E11-04-0305. Epub 2011 Oct 5.
Patterning of the Drosophila pupal eye is characterized by precise cell movements. In this paper, we demonstrate that these movements require an Arf regulatory cycle that connects surface receptors to actin-based movement. dArf6 activity-regulated by the Arf GTPase-activating proteins (ArfGAPs) dAsap and dArfGAP3 and the Arf GTP exchange factors Schizo and dPsd-promoted large cellular extensions; time-lapse microscopy indicated that these extensions presage cell rearrangements into correct epithelial niches. During this process, the Drosophila eye also requires interactions between surface Neph1/nephrin adhesion receptors Roughest and Hibris, which bind the adaptor protein Cindr (CD2AP). We provide evidence that Cindr forms a physical complex with dArfGAP3 and dAsap. Our data suggest this interaction sequesters ArfGAP function to liberate active dArf6 elsewhere in the cell. We propose that a Neph1/nephrin-Cindr/ArfGAP complex accumulates to limit local Arf6 activity and stabilize adherens junctions. Our model therefore links surface adhesion via an Arf6 regulatory cascade to dynamic modeling of the cytoskeleton, accounting for precise cell movements that organize the functional retinal field. Further, we demonstrate a similar relationship between the mammalian Cindr orthologue CD2AP and Arf6 activity in cell motility assays. We propose that this Cindr/CD2AP-mediated regulation of Arf6 is a widely used mechanism in emerging epithelia.
果蝇蛹期眼睛的模式形成以精确的细胞运动为特征。在本文中，我们证明这些运动需要一个 Arf 调节循环，将表面受体与肌动蛋白为基础的运动连接起来。dArf6 的活性受 Arf GTPase 激活蛋白（ArfGAPs）dAsap 和 dArfGAP3 的调节，以及 Arf GTP 交换因子 Schizo 和 dPsd 促进的大细胞延伸；延时显微镜表明，这些延伸预示着细胞重新排列到正确的上皮龛位。在此过程中，果蝇眼还需要表面 Neph1/nephrin 粘附受体 Roughest 和 Hibris 之间的相互作用，它们结合衔接蛋白 Cindr（CD2AP）。我们提供的证据表明，Cindr 与 dArfGAP3 和 dAsap 形成物理复合物。我们的数据表明，这种相互作用将 ArfGAP 功能隔离出来，从而在细胞的其他部位释放出活性 dArf6。我们提出，Neph1/nephrin-Cindr/ArfGAP 复合物的积累限制了局部 Arf6 活性，并稳定了黏着连接。因此，我们的模型通过 Arf6 调节级联将表面粘附与细胞骨架的动态建模联系起来，解释了组织功能视网膜区域的精确细胞运动。此外，我们在细胞迁移测定中证明了哺乳动物 Cindr 同源物 CD2AP 和 Arf6 活性之间存在类似的关系。我们提出，这种 Cindr/CD2AP 介导的 Arf6 调节是新兴上皮中广泛使用的机制。
