title: Filamin A interaction with the CXCR4 third intracellular loop regulates endocytosis and signaling of WT and WHIM-like receptors.
abstract: Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is a rare congenital immunodeficiency often caused by mutations in the last 10 to 19 C-terminal amino acids of CXCR4. These mutations impair CXCR4 internalization and increase responsiveness to CXCL12. The CXCR4 C-terminal domain (C-tail) also has a binding site for the actin-binding protein filamin A (FLNA); it is not known whether FLNA binds to WHIM CXCR4 mutants or whether this interaction is implicated in the hyperfunction of these receptors. Here we show that, in addition to interacting with the CXCR4 C-tail, FLNA interacted with a region in the receptor third intracellular loop (ICL3) spanning amino acids 238 to 246. This interaction involved specific FLNA repeats and was sensitive to Rho kinase inhibition. Deletion of the 238-246 motif accelerated CXCL12-induced wild-type (WT) receptor endocytosis but enabled CXCL12-mediated endocytosis and normalized signaling by the WHIM-associated receptor CXCR4(R334X). CXCL12 stimulation triggered CXCR4(R334X) internalization in FLNA-deficient M2 cells but not in the FLNA-expressing M2 subclone A7; this suggests a role for FLNA in stabilization of WHIM-like CXCR4 at the cell surface. FLNA increased β-arrestin2 binding to CXCR4(R334X) in vivo, which provides a molecular basis for FLNA-mediated hyperactivation of WHIM receptor signaling. We propose that FLNA interaction with ICL3 is central for endocytosis and signaling of WT and WHIM-like CXCR4 receptors.
authors.affiliation: Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Madrid, Spain; and.
authors.forename: Concepción
authors.initials: C
authors.lastname: Gómez-Moutón
authors.affiliation: Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Madrid, Spain; and.
authors.forename: Thierry
authors.initials: T
authors.lastname: Fischer
authors.affiliation: Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Madrid, Spain; and.
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Peregil
authors.affiliation: Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Madrid, Spain; and.
authors.forename: Sonia
authors.initials: S
authors.lastname: Jiménez-Baranda
authors.affiliation: Translational Medicine Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Stossel
authors.affiliation: Translational Medicine Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Nakamura
authors.affiliation: Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Madrid, Spain; and.
authors.forename: Santos
authors.initials: S
authors.lastname: Mañes
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D045744:Cell Line, Tumor; D004705:Endocytosis / Q000235:genetics*; D064448:Filamins / Q000737:chemistry / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007153:Immunologic Deficiency Syndromes / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D000081207:Primary Immunodeficiency Diseases; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs / Q000235:genetics; D019718:Receptors, CXCR4 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D014860:Warts / Q000235:genetics* / Q000378:metabolism
chemical_list: C527276:CXCR4 protein, human; D064448:Filamins; D019718:Receptors, CXCR4