Gliotactin, a novel marker of tricellular junctions, is necessary for septate junction development in Drosophila.
Septate junctions (SJs), similar to tight junctions, function as transepithelial permeability barriers. Gliotactin (Gli) is a cholinesterase-like molecule that is necessary for blood-nerve barrier integrity, and may, therefore, contribute to SJ development or function. To address this hypothesis, we analyzed Gli expression and the Gli mutant phenotype in Drosophila epithelia. In Gli mutants, localization of SJ markers neurexin-IV, discs large, and coracle are disrupted. Furthermore, SJ barrier function is lost as determined by dye permeability assays. These data suggest that Gli is necessary for SJ formation. Surprisingly, Gli distribution only colocalizes with other SJ markers at tricellular junctions, suggesting that Gli has a unique function in SJ development. Ultrastructural analysis of Gli mutants supports this notion. In contrast to other SJ mutants in which septa are missing, septa are present in Gli mutants, but the junction has an immature morphology. We propose a model, whereby Gli acts at tricellular junctions to bind, anchor, or compact SJ strands apically during SJ development.
Schulte
Joost
J
Dept. of Zoology, University of British Columbia, Vancouver, Canada.
Tepass
Ulrich
U
Auld
Vanessa J
VJ
D000818:Animals; D030801:Animals, Genetically Modified; D015415:Biomarkers; D015816:Cell Adhesion Molecules, Neuronal / Q000172:deficiency / Q000235:genetics; D002450:Cell Communication / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D002463:Cell Membrane Permeability / Q000235:genetics; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology* / Q000378:metabolism / Q000648:ultrastructure; D004817:Epidermis / Q000002:abnormalities / Q000378:metabolism / Q000648:ultrastructure; D004848:Epithelium / Q000002:abnormalities* / Q000378:metabolism / Q000648:ultrastructure; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D007365:Intercellular Junctions / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D008854:Microscopy, Electron; D023421:Models, Animal; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism
D015415:Biomarkers; D015816:Cell Adhesion Molecules, Neuronal; D029721:Drosophila Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C491321:Nrx protein, Drosophila; C094064:gliotactin; C093438:neuroligin 1