title: Control of CXCR2 activity through its ubiquitination on K327 residue.
abstract: BACKGROUND
  The interleukin-8 chemokine (IL-8) G-protein coupled receptor CXCR2 governs pro-inflammatory and pro-angiogenic responses in leukocytes and endothelial cells. At a molecular standpoint, CXCR2 is widely reported to operate through calcium flux, phosphoinoisitide 3 kinase (PI3K) and mitogen-activated protein kinase (MAPK). While CXCR2 trafficking is suspected to be intertwined with its signaling, the exact mechanism is not fully elucidated.
  
  
  RESULTS
  Here, we identified the lysine 327 within the CXCR2 C-terminal tail as a key residue for ubiquitination, internalization, and signaling. First, the substitution to an arginine of K327 mutation was associated with a reduction in CXCR2 poly-ubiquitination. While WT CXCR2 was rapidly internalized following IL-8 administration, K327R mutant remained at the plasma membrane. Finally, K327R mutant failed to promote the recruitment of β-arrestin2, as estimated by imagery and bioluminescence resonance transfer. As a consequence, the activation of intracellular signaling, including both early events such as ERK phosphorylation and the increase in calcium flux, and the latter activation of the AP1 and NF-κB transcription factors, was blunted.
  
  
  CONCLUSIONS
  Overall, our results demonstrate that CXCR2 ubiquitination on K327 residue modulates agonist-activated CXCR2 cell sorting and intracellular signaling. Thus, the inhibition of K327 ubiquitination might emerge as an effective mean to curb exacerbated CXCR2 signaling in several pathological conditions, such as inflammatory diseases and cancer.
authors.forename: Héloise M
authors.initials: HM
authors.lastname: Leclair
authors.forename: Sonia M
authors.initials: SM
authors.lastname: Dubois
authors.forename: Sandy
authors.initials: S
authors.lastname: Azzi
authors.forename: Julie
authors.initials: J
authors.lastname: Dwyer
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bidère
authors.affiliation: CNRS, UMR8104, 22 rue Mechain, Paris, 75014, France. Julie.gavard@inserm.fr.
authors.forename: Julie
authors.initials: J
authors.lastname: Gavard
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D057809:HEK293 Cells; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D008239:Lysine / Q000032:analysis* / Q000378:metabolism; D008969:Molecular Sequence Data; D021381:Protein Transport; D023063:Receptors, Interleukin-8B / Q000737:chemistry / Q000378:metabolism*; D016415:Sequence Alignment; D015398:Signal Transduction; D054875:Ubiquitination
chemical_list: D016209:Interleukin-8; D023063:Receptors, Interleukin-8B; D008239:Lysine