title: A tetraspanin regulates septate junction formation in Drosophila midgut.
abstract: Septate junctions (SJs) are membrane specializations that restrict the free diffusion of solutes through the paracellular pathway in invertebrate epithelia. In arthropods, two morphologically different types of septate junctions are observed; pleated (pSJs) and smooth (sSJs), which are present in ectodermally and endodermally derived epithelia, respectively. Recent identification of sSJ-specific proteins, Mesh and Ssk, in Drosophila indicates that the molecular compositions of sSJs and pSJs differ. A deficiency screen based on immunolocalization of Mesh identified a tetraspanin family protein, Tsp2A, as a newly discovered protein involved in sSJ formation in Drosophila Tsp2A specifically localizes at sSJs in the midgut and Malpighian tubules. Compromised Tsp2A expression caused by RNAi or the CRISPR/Cas9 system was associated with defects in the ultrastructure of sSJs, changed localization of other sSJ proteins, and impaired barrier function of the midgut. In most Tsp2A mutant cells, Mesh failed to localize to sSJs and was distributed through the cytoplasm. Tsp2A forms a complex with Mesh and Ssk and these proteins are mutually interdependent for their localization. These observations suggest that Tsp2A cooperates with Mesh and Ssk to organize sSJs.
authors: Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki 444-8787, Japan Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki 444-8585, Japan furuse@nips.ac.jp yizumi@nips.ac.jp.
authors: Yasushi
authors: Y
authors: Izumi
authors: Laboratory of Regeneration Biology, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan).
authors: Minako
authors: M
authors: Motoishi
authors: Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki 444-8787, Japan.
authors: Kyoko
authors: K
authors: Furuse
authors: Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki 444-8787, Japan Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki 444-8585, Japan furuse@nips.ac.jp yizumi@nips.ac.jp.
authors: Mikio
authors: M
authors: Furuse
mesh_terms: D000818:Animals; D004064:Digestive System / Q000196:embryology / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D005260:Female; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D059470:Tetraspanins / Q000235:genetics / Q000378:metabolism; D019108:Tight Junctions / Q000235:genetics / Q000378:metabolism*
chemical_list: D029721:Drosophila Proteins; D008565:Membrane Proteins; C577654:Ssk protein, Drosophila; D059470:Tetraspanins; C000613393:Tsp2A protein, Drosophila
keywords: Drosophila; Epithelial cells; Midgut; Smooth septate junction; Tetraspanin