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.

Simvastatin induces cell cycle arrest and inhibits proliferation of bladder cancer cells via PPARγ signalling pathway

“…Those effects could mediate important cell functions, dramatically alter cell morphology and loss the cell-to-cell tight junction. Accumulating evidences suggested EMT was involved in cancer invasion and metastasis5051. The association of Cytokeratin and Vimentin was also reported in the genesis of transitional cell carcinoma of urinary bladder patients, and therefore could be a helpful marker in the early diagnosis of transitional bladder carcinoma46.…”

Zebrafish pronephros tubulogenesis and epithelial identity maintenance are reliant on the polarity proteins Prkc iota and zeta

“…The zebrafish has emerged as a valuable model for ongoing basic and translational kidney research based on the conservation of nephrons composition between zebrafish and mammalian nephrons (Poureetezadi, et al, 2013; Marra, et al, 2014). The attributes of the zebrafish embryo pronephros, in particular, have provided a novel opportunity for in vivo analysis of tubulogenesis processes (Mitra, et al, 2012; Jung, et al, 2013) and investigation of the mechanisms involved in the morphogenesis of tubular epithelial cells, such as collective cell migration (Vasilyev, et al, 2009). Our study adds to this work by providing the first spatiotemporal characterization of tubulogenesis in the zebrafish pronephros.…”

Endosomal and Phagosomal SNAREs

“…The Qa-SNARE Stx16 locates at the Golgi apparatus (88,155,239,282) and in membrane domains (107) at recycling endosomes (39,155). Stx16 has also been detected at phagosomes by proteomics (Ref.…”