Sensory axons induce epithelial lipid microdomain remodeling and determine the distribution of junctions in the epidermis.

Epithelial cell properties are determined by the polarized distribution of membrane lipids, the cytoskeleton, and adhesive junctions. Epithelia are often profusely innervated, but little work has addressed how neurites affect epithelial organization. We previously found that basal keratinocytes in the zebrafish epidermis enclose axons in ensheathment channels sealed by autotypic junctions.

Developmental Neurobiology: It Takes Nrg to Separate Dendrites.

The development of sensory receptive fields requires the coordinated spatial patterning of neurites from multiple sensory neuron subtypes. A new study identifies a role for neuron-skin cell interactions in preventing the bundling of dendritic arbors from distinct neurons.

The regulation of cell size and branch complexity in the terminal cells of the Drosophila tracheal system.

The terminal cells of the larval Drosophila tracheal system extend dozens of branched cellular processes, most of which become hollow intracellular tubes that support gas exchange with internal tissues. Previously, we undertook a forward genetic mosaic screen to uncover the pathways regulating terminal cell size, morphogenesis, and the generation and maintenance of new intracellular tubes. Our initial work identified several mutations affecting terminal cell size and branch number, and suggested that branch complexity and cell size are typically coupled but could be genetically separated.

An Ichor-dependent apical extracellular matrix regulates seamless tube shape and integrity.

During sprouting angiogenesis in the vertebrate vascular system, and primary branching in the Drosophila tracheal system, specialized tip cells direct branch outgrowth and network formation. When tip cells lumenize, they form subcellular (seamless) tubes. How these seamless tubes are made, shaped and maintained remains poorly understood.

FoxA transcription factor Fork head maintains the intestinal stem/progenitor cell identities in Drosophila.

Understanding how somatic stem cells respond to tissue needs is important, since aberrant somatic stem cell behaviors may lead to tissue degeneration or tumorigenesis. Here, from an in vivo RNAi screen targeting transcription factors that regulate intestinal regeneration, we uncovered a requirement for the Drosophila FoxA transcription factor Fork head (Fkh) in the maintenance of intestinal stem/progenitor cell identities. FoxA/Fkh maintains the expressions of stem/progenitor cell markers and is required for stem cell proliferation during intestinal homeostasis and regeneration.

Seamless tube shape is constrained by endocytosis-dependent regulation of active Moesin.

Most tubes have seams (intercellular or autocellular junctions that seal membranes together into a tube), but "seamless" tubes also exist. In Drosophila, stellate-shaped tracheal terminal cells make seamless tubes, with single branches running through each of dozens of cellular extensions. We find that mutations in braided impair terminal cell branching and cause formation of seamless tube cysts.