title: Syntaxin 16 regulates lumen formation during epithelial morphogenesis.
abstract: The formation and maintenance of cell-cell junctions, both under physiological and pathological conditions, requires the targeting and trafficking of junctional proteins. Proteins of the syntaxin (Stx)-family localize to a variety of subcellular membranes and contribute to intracellular transport of cargo by regulating vesicle fusion events at these sites. Unlike plasma membrane localized Stxs, the roles of endosome- and Golgi-localized stx proteins in epithelial morphogenesis are less understood. Here we show that Stx16- an endosome- and Golgi-localized target-membrane soluble N-ethylmaleimide attachment protein receptor (t-SNARE) that plays a role in membrane trafficking between these compartments - is essential for lumen development. In cultured Madin Darby Canine Kidney (MDCK) cells, Stx16 was selectively upregulated as sparsely plated cells attained confluency. Stx16-depleted confluent monolayers consistently showed lower transepithelial resistance than control monolayers, and failed to maintain endogenous and ectopically expressed E-cadherin at the adherens junctions due to decreased recycling. We further found that whereas cysts formed by MDCK cells cultured in Matrigel have a single hollow lumen, those formed by stx16-depleted counterparts had multiple lumens, due to abnormal orientiation of the mitotic spindle. Finally, a similar role for stx16 function in vivo is indicated by our analysis of pronephric-duct development in zebrafish expressing the claudinB:lynGFP transgene; lack of stx16 function in this structure (in stx16-morphant embryos) led to the development of enlarged, torturous pronephric ducts with more than one lumen. Taken together, our in vitro and in vivo studies establish a role for Stx16 in maintaining the integrity of cell-cell junctions, and thereby in morphogenesis of the kidney epithelial lumen.
authors.affiliation: Department of Anatomy and Cell Biology, University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Jae-Joon
authors.initials: JJ
authors.lastname: Jung
authors.forename: Shivangi M
authors.initials: SM
authors.lastname: Inamdar
authors.forename: Ajit
authors.initials: A
authors.lastname: Tiwari
authors.forename: Ding
authors.initials: D
authors.lastname: Ye
authors.forename: Fang
authors.initials: F
authors.lastname: Lin
authors.forename: Amit
authors.initials: A
authors.lastname: Choudhury
mesh_terms: D000818:Animals; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D002452:Cell Count; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D003094:Collagen; D004285:Dogs; D004338:Drug Combinations; D004625:Embryo, Nonmammalian; D011992:Endosomes / Q000378:metabolism / Q000648:ultrastructure; D018507:Gene Expression Regulation, Developmental; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure; D007365:Intercellular Junctions / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D007668:Kidney / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D007797:Laminin; D061985:Madin Darby Canine Kidney Cells; D021381:Protein Transport; D011509:Proteoglycans; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D008941:Spindle Apparatus / Q000378:metabolism / Q000648:ultrastructure; D051438:Syntaxin 16 / Q000235:genetics / Q000378:metabolism*; D019076:Transgenes; D015027:Zebrafish
chemical_list: D015820:Cadherins; D004338:Drug Combinations; D007797:Laminin; D011509:Proteoglycans; D050600:SNARE Proteins; D051438:Syntaxin 16; C059485:matrigel; D003094:Collagen