title: Role of the C terminus of the interleukin 8 receptor in signal transduction and internalization.
abstract: Interleukin 8 (IL-8) is a potent neutrophil chemoattractant and activator. Two IL-8 receptor subtypes, A and B, are expressed in neutrophils. In this work, we analyzed the role of the C terminus domain of the IL-8 receptor on the signal transduction and receptor internalization mechanisms. The IL-8 receptor A was tagged with an epitope corresponding to the monoclonal antibody 1D4 to monitor the localization of the IL-8 receptor. We demonstrated IL-8-dependent receptor internalization by monitoring the density of surface 125I-labeled IL-8 binding sites and by immunofluorescence microscopy. Truncation of the last 27 amino acids of the IL-8 receptor A severely impaired the IL-8-induced internalization of the receptor. Of importance was the observation that binding of IL-8 to receptors A and B triggered a dramatically faster rate of internalization of receptor B than receptor A, suggesting that the heterologous C termini among receptor subtypes modulate the rate of internalization of IL-8 receptors. However, substitution of the C terminus of the receptor subtype A for the C terminus of receptor B reduced the internalization rate of receptor A. Furthermore, we found that the rate of internalization of IL-8 receptor B triggered by IL-8 was faster than the one induced by the IL-8-related peptide, melanoma growth stimulatory activity. Studies with human neutrophils pretreated with 100 nM IL-8 for 5 min revealed a positive and a negative calcium response mediated by receptors A and B, respectively. In contrast, neutrophils pretreated with melanoma growth stimulatory activity showed positive calcium responses to both receptors A and B. These data suggest that the neutrophil responses mediated by IL-8 are modulated by the rate of internalization of receptors.
authors.affiliation: Department of Physiology and Biophysics, Sealy Center for Molecular Science, University of Texas Medical Branch, Galveston, Texas 77555, USA.
authors.forename: G N
authors.initials: GN
authors.lastname: Prado
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
authors.forename: N
authors.initials: N
authors.lastname: Wilkinson
authors.forename: B
authors.initials: B
authors.lastname: Cousins
authors.forename: J
authors.initials: J
authors.lastname: Navarro
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D001483:Base Sequence; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D054360:Chemokine CXCL1; D019743:Chemokines, CXC; D002630:Chemotactic Factors / Q000494:pharmacology; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary; D000939:Epitopes / Q000276:immunology; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D016209:Interleukin-8 / Q000378:metabolism / Q000494:pharmacology; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D011869:Radioligand Assay; D018123:Receptors, Interleukin / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D023062:Receptors, Interleukin-8A; D015398:Signal Transduction
chemical_list: D015703:Antigens, CD; C475829:CXCL1 protein, human; D054360:Chemokine CXCL1; D019743:Chemokines, CXC; D002630:Chemotactic Factors; D018076:DNA, Complementary; D000939:Epitopes; D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D016209:Interleukin-8; D018123:Receptors, Interleukin; D023062:Receptors, Interleukin-8A; D002118:Calcium