title: β-Arrestin recruitment and G protein signaling by the atypical human chemokine decoy receptor CCX-CKR.
abstract: Chemokine receptors form a large subfamily of G protein-coupled receptors that predominantly activate heterotrimeric Gi proteins and are involved in immune cell migration. CCX-CKR is an atypical chemokine receptor with high affinity for CCL19, CCL21, and CCL25 chemokines, but is not known to activate intracellular signaling pathways. However, CCX-CKR acts as decoy receptor and efficiently internalizes these chemokines, thereby preventing their interaction with other chemokine receptors, like CCR7 and CCR9. Internalization of fluorescently labeled CCL19 correlated with β-arrestin2-GFP translocation. Moreover, recruitment of β-arrestins to CCX-CKR in response to CCL19, CCL21, and CCL25 was demonstrated using enzyme-fragment complementation and bioluminescence resonance energy transfer methods. To unravel why CCX-CKR is unable to activate Gi signaling, CCX-CKR chimeras were constructed by substituting its intracellular loops with the corresponding CCR7 or CCR9 domains. The signaling properties of chimeric CCX-CKR receptors were characterized using a cAMP-responsive element (CRE)-driven reporter gene assay. Unexpectedly, wild type CCX-CKR and a subset of the chimeras induced an increase in CRE activity in response to CCL19, CCL21, and CCL25 in the presence of the Gi inhibitor pertussis toxin. CCX-CKR signaling to CRE required an intact DRY motif. These data suggest that inactive Gi proteins impair CCX-CKR signaling most likely by hindering the interaction of this receptor with pertussis toxin-insensitive G proteins that transduce signaling to CRE. On the other hand, recruitment of the putative signaling scaffold β-arrestin to CCX-CKR in response to chemokines might allow activation of yet to be identified signal transduction pathways.
authors: Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands.
authors: Anne O
authors: AO
authors: Watts
authors: Folkert
authors: F
authors: Verkaar
authors: Miranda M C
authors: MM
authors: van der Lee
authors: Claudia A W
authors: CA
authors: Timmerman
authors: Martien
authors: M
authors: Kuijer
authors: Jody
authors: J
authors: van Offenbeek
authors: Lambertus H C J
authors: LH
authors: van Lith
authors: Martine J
authors: MJ
authors: Smit
authors: Rob
authors: R
authors: Leurs
authors: Guido J R
authors: GJ
authors: Zaman
authors: Henry F
authors: HF
authors: Vischer
mesh_terms: D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D001667:Binding, Competitive / Q000187:drug effects; D015153:Blotting, Western; D016466:CHO Cells; D045744:Cell Line, Tumor; D054415:Chemokine CCL19 / Q000378:metabolism / Q000494:pharmacology; D054421:Chemokine CCL21 / Q000378:metabolism / Q000494:pharmacology; D019742:Chemokines, CC / Q000378:metabolism / Q000494:pharmacology; D006224:Cricetinae; D003412:Cricetulus; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D037342:Pertussis Toxin / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D054388:Receptors, CCR / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D000071557:beta-Arrestins
chemical_list: C408223:ACKR4 protein, human; D019390:Arrestins; C108074:CCL25 protein, human; D054415:Chemokine CCL19; D054421:Chemokine CCL21; D019742:Chemokines, CC; D054388:Receptors, CCR; D000071557:beta-Arrestins; D049452:Green Fluorescent Proteins; D037342:Pertussis Toxin; D019206:GTP-Binding Protein alpha Subunits, Gi-Go