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Sorting nexin‐25, a novel member of the dopamine receptor signalplex, up‐regulates D 1 and D 2 dopamine receptor expression in HEK293 cells
Author(s) -
Free R Benjamin,
Hazelwood Lisa A,
Spalding Heather N,
Cabrera David M,
Sibley David R
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.21.5.a423-d
Subject(s) - hek 293 cells , internalization , sorting nexin , microbiology and biotechnology , receptor , endosome , g protein coupled receptor , 5 ht5a receptor , enzyme linked receptor , dopamine receptor , transfection , dopamine , intracellular , biology , chemistry , signal transduction , cell culture , neuroscience , biochemistry , genetics
Dopamine receptors (DARs) do not exist as singular independent units within the synaptic membrane, but are part of large macromolecular complexes of interacting proteins. These interacting proteins influence the receptor in a variety of ways. Our current studies employ a co‐immunoprecipitation assay for DARs from transfected cell lines, coupled with mass spectrometry sequencing to identify interacting partners. One protein identified this way was sorting nexin‐25 (SNX25). Mammalian SNXs have been suggested to be involved in intracellular trafficking, internalization, and endosomal recycling or sorting. The physiological role of SNX25 is unknown. Using radioligand binding assays, we found that increasing the expression levels of SNX25 in HEK293 cells increased the amount of D 1 and D 2 receptor expressed. This increase in receptor expression was accompanied by an alteration in the subcellular distribution of the receptors as seen using confocal microscopy (D 1 DAR) and intact cell binding assays (D 2 DAR). SNX25 over‐expression also caused an increase in both D 1 and D 2 receptor‐mediated signaling in HEK293 cells. In contrast, SNX25 over‐expression does not appear to affect D 1 DAR desensitization. Overall, these data suggest that SNX25 regulates the intracellular trafficking of D 1 and D 2 DARs. The mechanisms underlying these effects are being investigated. Supported by The NIH intramural program.