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The role of SNARE proteins in trafficking and function of Urea Transporter UT‐A1
Author(s) -
Mistry Abinash C.,
Mallick Rickta,
Klein Janet D.,
Fröhlich Otto,
Weimbs Thomas,
Chen Guangping,
Sands Jeff M.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a906-c
Subject(s) - biology , snap23 , syntaxin , snare complex , microbiology and biotechnology , syntaxin 3 , synaptobrevin , immunoprecipitation , transport protein , membrane protein , exocytosis , biochemistry , membrane , vesicle associated membrane protein 8 , synaptic vesicle , vesicle , gene
Trafficking of the urea transporter UT‐A1 to the plasma membrane is key in vasopressin‐regulated urea transport, but the mechanisms remain unclear. Our experiments show UT‐A1 involvement with several SNARE‐mediated accessory proteins involved in orientation of proteins in the plasma membrane. One group of proteins involved in membrane orientation is the syntaxin family. We recently reported that snapin is important in the interaction of UT‐A1 with syntaxin‐4 and SNAP23 (t‐SNARE). UT‐A1‐MDCK cells with adenoviral‐mediated over‐expression of both snapin and syntaxin‐4, show that the association of UT‐A1 with syntaxin‐4 is enhanced snapin. Over‐expression of syntaxin‐4 alone showed minimal UT‐A1/syntaxin‐4 binding. Confocal microscopy of UT‐A1 and snapin show colocalization in both cytoplasm and plasma membrane. Co‐injection of UT‐A1 with snapin cRNA (2 ug) in Xenopus oocytes increased urea influx. Co‐injection of UT‐A1 with t‐SNARE without snapin, decreased urea influx. These results suggest that snapin promotes the initial docking of UT‐A1 at the plasma membrane to form a SNARE complex. When we treated UT‐A1‐MDCK cells with vasopressin or forskolin, UT‐A1 and snapin were redistributed to the plasma membrane. Collectively, our data support a role for a snapin syntaxin‐4/SNAP23 mediated UT‐A1 docking complex in vasopressin‐regulated trafficking of UT‐A1 in UT‐A1‐MDCK cells. In addition, we verified that the components of the snapin/t‐SNARE/UT‐A1 complex are present in rat inner medulla, suggesting that this mechanism may be physiologically important. Support: NIDDK and AHA