van Impel Andreas, Schumacher Sabine, Draga Margarethe, Herz Hans-Martin, Grosshans Jörg, Müller H Arno J
Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee, UK.
Development. 2009 Mar;136(5):813-22. doi: 10.1242/dev.026203. Epub 2009 Feb 11.
The Drosophila guanine nucleotide exchange factor Pebble (Pbl) is essential for cytokinesis and cell migration during gastrulation. In dividing cells, Pbl promotes Rho1 activation at the cell cortex, leading to formation of the contractile actin-myosin ring. The role of Pbl in fibroblast growth factor-triggered mesoderm spreading during gastrulation is less well understood and its targets and subcellular localization are unknown. To address these issues we performed a domain-function study in the embryo. We show that Pbl is localized to the nucleus and the cell cortex in migrating mesoderm cells and found that, in addition to the PH domain, the conserved C-terminal tail of the protein is crucial for cortical localization. Moreover, we show that the Rac pathway plays an essential role during mesoderm migration. Genetic and biochemical interactions indicate that during mesoderm migration, Pbl functions by activating a Rac-dependent pathway. Furthermore, gain-of-function and rescue experiments suggest an important regulatory role of the C-terminal tail of Pbl for the selective activation of Rho1-versus Rac-dependent pathways.
果蝇鸟嘌呤核苷酸交换因子Pebble(Pbl)在原肠胚形成期间的胞质分裂和细胞迁移过程中至关重要。在分裂细胞中,Pbl促进细胞皮质处的Rho1激活,导致收缩性肌动蛋白-肌球蛋白环的形成。Pbl在原肠胚形成期间成纤维细胞生长因子触发的中胚层扩展中的作用尚不太清楚,其靶点和亚细胞定位也未知。为了解决这些问题,我们在胚胎中进行了一项结构域功能研究。我们发现Pbl定位于迁移的中胚层细胞的细胞核和细胞皮质,并发现除了PH结构域外,该蛋白保守的C末端尾巴对于皮质定位至关重要。此外,我们表明Rac途径在中胚层迁移过程中起着至关重要的作用。遗传和生化相互作用表明,在中胚层迁移过程中,Pbl通过激活Rac依赖性途径发挥作用。此外,功能获得和拯救实验表明Pbl的C末端尾巴对于Rho1与Rac依赖性途径的选择性激活具有重要的调节作用。