Membrane Dynamics During Epithelial Tube Fusion

We study how tubular networks develop from initially separate units. In the vascular system separate endothelial sprouts fuse to build tubular bridges (anastomoses). Despite the fundamental role of this process in organogenesis and pathology, the mechanisms that govern epithelial tube fusion are not well understood. Tube fusion events resembling vascular anastomosis formation also occur during development of the tracheal system. Tube fusion involves directed migration of cells towards the fusion point, formation of a new cell-cell junction, and finally the connection of adjacent tubes. We aim to understand the mechanism of membrane fusion during the connection of tracheal tubes. We use in vivo cell labeling techniques combined with high-resolution light and electron microscopy to define the intermediates of the fusion process at the cellular and ultrastructural level. To identify new components of the underlying cellular machinery, we characterize fusion-defective mutants, which we isolated in genetic screens (Caviglia and Luschnig 20143. Answering basic questions about lumen formation and conversion of cellular topology in the Drosophila tracheal tube fusion model can provide a conceptual framework to help elucidate similar processes, such as vascular anastomosis and pronephric duct fusion, in more complex vertebrate systems.