title: Sorting nexin 27 protein regulates trafficking of a p21-activated kinase (PAK) interacting exchange factor (β-Pix)-G protein-coupled receptor kinase interacting protein (GIT) complex via a PDZ domain interaction.
abstract: Sorting nexin 27 (SNX27) is a 62-kDa protein localized to early endosomes and known to regulate the intracellular trafficking of ion channels and receptors. In addition to a PX domain, SNX27 is the only sorting family member that contains a PDZ domain. To identify novel SNX27-PDZ binding partners, we performed a proteomic screen in mouse principal kidney cortical collecting duct cells using a GST-SNX27 fusion construct as bait. We found that β-Pix (p21-activated kinase-interactive exchange factor), a guanine nucleotide exchange factor for the Rho family of small GTPases known to regulate cell motility directly interacted with SNX27. The association of β-Pix and SNX27 is specific for β-Pix isoforms terminating in the type-1 PDZ binding motif (ETNL). In the same screen we also identified Git1/2 as a potential SNX27 interacting protein. The interaction between SNX27 and Git1/2 is indirect and mediated by β-Pix. Furthermore, we show recruitment of the β-Pix·Git complex to endosomal sites in a SNX27-dependent manner. Finally, migration assays revealed that depletion of SNX27 from HeLa and mouse principal kidney cortical collecting duct cells significantly decreases cell motility. We propose a model by which SNX27 regulates trafficking of β-Pix to focal adhesions and thereby influences cell motility.
authors.affiliation: Cell Biology and Physiology Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20982, USA.
authors.forename: Julie L
authors.initials: JL
authors.lastname: Valdes
authors.forename: Jingrong
authors.initials: J
authors.lastname: Tang
authors.forename: Mark I
authors.initials: MI
authors.lastname: McDermott
authors.forename: Jean-Cheng
authors.initials: JC
authors.lastname: Kuo
authors.forename: Seth P
authors.initials: SP
authors.lastname: Zimmerman
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Wincovitch
authors.forename: Clare M
authors.initials: CM
authors.lastname: Waterman
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Milgram
authors.forename: Martin P
authors.initials: MP
authors.lastname: Playford
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002465:Cell Movement / Q000502:physiology; D022001:Focal Adhesions / Q000235:genetics / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D041681:NIH 3T3 Cells; D054731:PDZ Domains; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D064067:Rho Guanine Nucleotide Exchange Factors; D058305:Sorting Nexins / Q000235:genetics / Q000378:metabolism*
chemical_list: C576606:ARHGEF7 protein, human; D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; C485647:GIT1 protein, human; C430213:GIT2 protein, human; D020690:GTPase-Activating Proteins; C120766:Git1 protein, mouse; C120767:Git2 protein, mouse; D020662:Guanine Nucleotide Exchange Factors; D036341:Intercellular Signaling Peptides and Proteins; D046912:Multiprotein Complexes; D010750:Phosphoproteins; D064067:Rho Guanine Nucleotide Exchange Factors; C522885:SNX27 protein, human; C500393:Snx27 protein, mouse; D058305:Sorting Nexins