Differential Effects of Posttranslational Modifications of CXCL8/Interleukin-8 on CXCR1 and CXCR2 Internalization and Signaling Properties.
CXCL8 or interleukin (IL)-8 directs neutrophil migration and activation through interaction with CXCR1 and CXCR2 that belong to the family of G protein-coupled receptors (GPCRs). Naturally occurring posttranslational modifications of the NH₂-terminal region of CXCL8 affect its biological activities, but the underlying molecular mechanisms are only partially understood. Here, we studied the implications of site-specific citrullination and truncation for the signaling potency of CXCL8. Native CXCL8(1-77), citrullinated [Cit5]CXCL8(1-77) and the major natural isoform CXCL8(6-77) were chemically synthesized and tested in internalization assays using human neutrophils. Citrullinated and truncated isoforms showed a moderately enhanced capacity to induce internalization of CXCR1 and CXCR2. Moreover, CXCL8-mediated activation of Gαi-dependent signaling through CXCR1 and CXCR2 was increased upon modification to [Cit5]CXCL8(1-77) or CXCL8(6-77). All CXCL8 variants promoted recruitment of β-arrestins 1 and 2 to CXCR1 and CXCR2. Compared to CXCL8(1-77), CXCL8(6-77) showed an enhanced potency to recruit β-arrestin 2 to both receptors, while for [Cit5]CXCL8(1-77) only the capacity to induce β-arrestin 2 recruitment to CXCR2 was increased. Both modifications had no biasing effect, i.e., did not alter the preference of CXCL8 to activate either Gαi-protein or β-arrestin-dependent signaling through its receptors. Our results support the concept that specific chemokine activities are fine-tuned by posttranslational modifications.
['Vacchini|Alessandro|A|', 'Mortier|Anneleen|A|', 'Proost|Paul|P|0000-0002-0133-5545', 'Locati|Massimo|M|', 'Metzemaekers|Mieke|M|', 'Borroni|Elena Monica|EM|']
D004705:Endocytosis D006801:Humans D016209:Interleukin-8 D009504:Neutrophils D011485:Protein Binding D054730:Protein Interaction Domains and Motifs D011499:Protein Processing, Post-Translational D021381:Protein Transport D023062:Receptors, Interleukin-8A D023063:Receptors, Interleukin-8B D015398:Signal Transduction D000071557:beta-Arrestins
posttranslational modifications CXCL8 G protein-coupled receptor chemokine