|Institution:||University of Iceland|
|Full text PDF:||http://hdl.handle.net/1946/20263|
Drosophila larval tracheal terminal cells are highly branched cells with subcellular tubes for gas transport running through their branches. As they grow rapidly over a few days they produce a large quantity of membrane for delivery to both the outer plasma membrane and the plasma membrane making up the subcellular tube. We have found that two proteins involved in membrane vesicle trafficking, Rab8 and tango1, first identified in a small-scale RNAi screen and a MARCM screen, play important roles in terminal cell development. The depletion of Rab8, a small GTPase involved in trans-Golgi network-to-plasma membrane trafficking, results in reduced number of branching points and abnormal tube morphology as a result of reduced membrane delivery to the basolateral membrane. The depletion of Tango1, a transmembrane protein required for the loading of collagen into vesicles at the endoplasmic reticulum exit sites, in terminal cells results in reduced number of branching points, as well as defective luminal air-filling in a collagen-independent manner. Additionally, we show that Drosophila Tango1 is required for the delivery of multiple transmembrane and secreted proteins from the ER, suggesting a more general role for Drosophila Tango1 in trafficking of molecules from ER to Golgi than its mammalian counterpart. For the discovery of genes involved in terminal cell development a quantitative evaluation of defects is important. Therefore, we designed an unbiased quantitative scheme analyzing cellular morphology of terminal cells using imaging and automated quantification. An unbiased quantitative approach allows for comparison of wild type and genetically modified terminal cells. As many genes identified in terminal cell development are conserved in mammals, these studies can shed a light on analogous pathways.