Early Secretory Events are Required for Seamless Tubulogenesis and Branching Morphogenesis in Drosophila Terminal Cells

Biological tubes serve as conduits through which gas, nutrients and other important fluids are delivered to tissues. Most biological tubes are formed using cellular junctions. However, seamless tubes form without the use of junctions and are found throughout mammalian vasculature. The Drosophila tracheal system is a network of air-filled tubes that delivers oxygen to hypoxic tissues. Within the tracheal system specialized cells called terminal cells branch extensively and form seamless tubes. Vesicle trafficking has been shown to be a major contributor to seamless tube formation, but the identity of membrane being contributed to the tube, and the protein regulators guiding this process, largely remain a mystery. In the present study, we demonstrate that early secretory pathway regulators play a role in both branching morphogenesis and seamless tubulogenesis of the terminal cell