title: Cellular distribution of innexin 1 and 2 gap junctional channel proteins in epithelia of the Drosophila embryo.
abstract: Invertebrate gap junctions are composed of Innexin channel proteins that are structurally and functionally analogous to the connexins in vertebrates. In situ hybridization experiments have shown that most of the eight known innexin genes in Drosophila are expressed in a complex and overlapping temporal and spatial profile, with several members showing high levels of expression in developing epithelia of the embryo. To further study the cellular roles of Innexins, we have generated antibodies against Innexins 1 and 2 and studied their protein distribution in the developing embryo. We find that both Innexins are co-expressed in a number of epithelial tissues including the epidermis, the gut and the salivary glands. On the cellular level, we find both proteins localized to the membranes of epithelial cells. Immunohistochemical analysis using cell polarity markers indicates that Innexin 1 is predominantly localized to the baso-lateral domain of epithelial cells, basal to septate junctions. In contrast, we find a variable positioning of Innexin 2 along the apico-basal axis of epithelial cells depending on the type of tissue and organ. Our findings suggest that the distribution of Innexin channel proteins to specific membrane domains of epithelial cells is regulated by tissue specific factors during the development of epithelia in the fly embryo.
authors.affiliation: Institut für Molekulare Physiologie und Entwicklungsbiologie der Universität Bonn, Bonn, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Bauer
authors.forename: Julia
authors.initials: J
authors.lastname: Martini
authors.forename: Corinna
authors.initials: C
authors.lastname: Lehmann
authors.forename: Michael
authors.initials: M
authors.lastname: Hoch
mesh_terms: D000818:Animals; D016764:Cell Polarity / Q000502:physiology*; D017630:Connexins / Q000378:metabolism*; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000378:metabolism; D004817:Epidermis / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism*; D017629:Gap Junctions / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D007413:Intestinal Mucosa / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D008854:Microscopy, Electron; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D012469:Salivary Glands / Q000378:metabolism
chemical_list: D017630:Connexins; D029721:Drosophila Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C120024:inx2 protein, Drosophila; C079326:ogre protein, Drosophila