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是组织协调运动的必要条件。果蝇气管网络是由管状外胚层上皮的分支、迁移和融合形成的。气管尖端细胞位于即将融合的每个分支的末端。尖端细胞扩展丝状足来寻找目标，然后改变细胞形状，使其成为一个无缝的环，以允许通过管腔。细胞粘附分子DE-cadherin是气管形成所必需的，它在接触部位聚集形成一个环，标志着管腔进入的位置，这对融合是必不可少的。de -钙粘蛋白在一个分支亚群的尖端细胞中的表达依赖于蜗牛，一个锌指基因在所有尖端细胞中表达。这种蜗牛突变的尖端细胞不能相互粘附，而是通过延长丝状足继续寻找替代靶标。我们提出的证据表明，蜗牛正调节de -钙粘蛋白基因的转录，猎枪。DE-cadherin的过表达修复了蜗牛突变体中一个融合点的缺陷，证明了DE-cadherin在目标识别中的重要作用，并确定了蜗牛在气管形态发生中是细胞粘附和运动的关键调节剂。这些研究证明，气管系统是研究细胞形态发生过程中运动和粘附的理想系统。为了便于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.