Single cell analyzes of cell behavior In Drosophila tracheal morphogenesis

在动物形态发生过程中，细胞运动和粘附的协调对于组织的协调运动是必不可少的。果蝇的气管网络是由管状外胚层上皮细胞分支、迁移和融合而形成的。气管尖端细胞位于每个将要融合的分支的末端。尖端细胞延伸丝状伪足以寻找目标，随后将其细胞形状改变为无缝环以允许管腔通过。细胞粘附分子DE-钙粘蛋白是气管形成所需的，并在接触部位积聚形成标记管腔进入部位的环，并且对于融合是必不可少的。DE-钙粘蛋白的表达在尖端细胞的分支的一个子集是依赖于蜗牛，锌指基因表达在所有尖端细胞。这种蜗牛突变体尖端细胞未能相互粘附，并继续通过延伸长丝状伪足寻找替代靶点。我们目前的证据表明蜗牛积极调节DE-钙粘蛋白基因的转录，鸟枪。DE-cadherin的过表达弥补了田螺突变体中一个融合点的缺陷，证明DE-cadherin在靶标识别中的重要作用，并确定田螺是气管形态发生中细胞粘附和运动的关键调节因子，这些研究证明气管系统是研究细胞形态发生中细胞运动和粘附的理想系统。为了促进活体动物气管形成的研究，我们开发了GFP表达载体，使我们能够观察活体胚胎中气管细胞的迁移。

Coordination of cell motility and adhesion is essential for concerted movement of tissues during animal morphogenesis. The Drosophila tracheal network is formed by branching, migration and fusion of tubular ectodermal epithelia. The tracheal tip cell is located at the end of each branch that are going to fuse. Tip cells extend filopodia to search for targets and later change their cell shape to that of a seamless ring to allow passage of lumen. The cell adhesion molecule DE-cadherin is required for tracheal formation, and accumulates at the site of contact to form a ring that marks the site of lumen entry, and is essential for the fusion. DE-cadherin expression in tip cells of a subset of branches is dependent on escargot, a zinc finger gene expressed in all tip cells. Such escargot mutant tip cells failed to adhere to each other and continued to search for alternative targets by extending long filopodia. We present evidence indicating escargot positively regulates transcription of the DE-cadherin gene, shotgun. Overexpression of DE-cadherin rescued the defect in one of the fusion points in escargot mutants, demonstrating an essential role of DE-cadherin in target recognition and identifying escargot as a key regulator of cell adhesion and motility in tracheal morphogenesis.These studies has proven that tracheal system is ideal for study of cell motility and adhesion during morphogenesis. To facilitate the study of tracheal formation in live animals, we have developed gfp expression vector that enabled us to observe tracheal cell migration in living embryos.