Lymphocyte chemotaxis is a complex process by which cells move within tissues and across barriers such as vascular endothelium usually stimulated chemokines stromal cell-derived factor-1 (CXCL12) acting via G protein-coupled receptors. Because members of this receptor family are regulated (“desensitized”) kinase (GRK)-mediated phosphorylation β-arrestin binding, we examined signaling chemotactic responses in splenocytes derived from knockout mice deficient various β-arrestins GRKs, with the...

Members of the chemokine receptor family CCR5 and CXCR4 have recently been shown to be involved in entry human immunodeficiency virus (HIV) into target cells. Here, we investigated regulation rat basophilic leukemia cells (RBL-2H3) stably transfected with wild type (Wt CXCR4) or a cytoplasmic tail deletion mutant (DeltaCyto CXCR4. The ligand, stromal cell derived factor-1 (SDF-1) stimulated higher G-protein activation, inositol phosphate generation, more sustained calcium elevation...

An intact chemotactic response is vital for leukocyte trafficking and host defense. Opiates are known to exert a number of immunomodulating effects in vitro vivo, we sought determine whether they were capable inhibiting chemokine-induced directional migration human leukocytes, if so, ascertain the mechanism involved. The endogenous opioid met-enkephalin induced monocyte chemotaxis pertussis toxin–sensitive manner. Met-enkephalin, as well morphine, inhibited IL-8–induced neutrophils...

CXCL8 (also known as IL-8) activates CXCR1 and CXCR2 to mediate neutrophil recruitment trigger cytotoxic effect at sites of infection. Under physiological conditions, could exist monomers, dimers, or a mixture monomers dimers. Therefore, both forms interact with different affinities potencies cellular responses. In the present study, we have used "trapped" nonassociating monomer (L25NMe) nondissociating dimer (R26C) investigate their activities for human neutrophils that express receptors...

Abstract The chemokine receptors, CXCR1 and CXCR2, couple to Gαi induce leukocyte recruitment activation at sites of inflammation. Upon by CXCL8, these receptors become phosphorylated, desensitized, internalized. In this study, we investigated the role different G protein-coupled receptor kinases (GRKs) in CXCR1- CXCR2-mediated cellular functions. To that end, short hairpin RNA was used inhibit GRK2, 3, 5, 6 RBL-2H3 cells stably expressing or CXCL8-mediated regulation were assessed....

Abstract The formylpeptide (fMLP) and C5a chemoattractants were previously shown to cross-desensitize each other's ability mobilize Ca2+ in leukocytes but not affect nonchemoattractant Ca(2+)-mobilizing receptors, vice versa. Our data show that all receptors studied underwent homologous desensitization. Interestingly, peptide (fMLP, C5a, IL-8) desensitized responses, had no effect on a purinergic receptor. Lipid chemoattractant (PAF leukotriene B4) also by In the presence of cytochalasin B,...

Abstract IL-8 (or CXCL8) activates the receptors CXCR1 (IL-8RA) and CXCR2 (IL-8RB) to induce chemotaxis in leukocytes, but only mediates cytotoxic cross-regulatory signals. This may be due rapid internalization of CXCR2. To investigate roles intracellular domains receptor regulation, wild-type, chimeric, phosphorylation-deficient, cytoplasmic tail (C-tail) deletion mutants both were expressed RBL-2H3 cells studied for cellular activation, phosphorylation, desensitization, internalization....

To define the regulation of chemoattractant receptors, epitope-tagged human formyl peptide and C5a receptor cDNAs (ET-FR ET-C5aR) were stably expressed in rat basophilic leukemia, RBL-2H3 cells. An antibody (12CA5) specific to ET was used immunoprecipitate ET-FR ET-C5aR. fMLP caused time- dose-dependent phosphorylation their respective receptors. Phosphorylated migrated as a single broad band between 50 70 kDa on SDS-polyacrylamide gel electrophoresis, whereas ET-C5aR exhibited both fast...

Neutrophils and transfected RBL-2H3 cells were used to investigate the mechanism of cross-regulation human interleukin-8 (IL-8) receptors CXCR1 CXCR2 by chemoattractants. In neutrophils, Ca²⁺ mobilization CXCR2-specific chemokine, growth-related oncogene α (Groα), was desensitized prior exposure chemoattractants<i>N</i>-formylated peptides (fMLP) or a complement cleavage product (C5a). contrast, did not desensitize latter receptors. To this phenomenon, stably expressed in mediated...

Platelet activating factor (PAF) interacts with cell surface receptors to mediate inflammatory responses.

Regulation of the immune response requires cooperation multiple signals in activation effector cells. For example, T cells require emanating from both TCR for antigen (upon recognition MHC/antigenic peptide) and receptors costimulatory molecules (e.g., CD80 CD60) full activation. Here we show that IgE-mediated reactions conjunctiva also signals. Immediate hypersensitivity were inhibited mice deficient macrophage inflammatory protein-1alpha (MIP-1alpha) despite normal numbers tissue mast no...

To define the molecular mechanisms of cross-regulation among chemoattractant receptors, we stably co-expressed, in a rat basophilic leukemia (RBL-2H3) cell line, epitope-tagged receptors for chemoattractants formylmethionylleucylphenylalanine (fMLP), peptide fifth component complement system (C5a), and interleukin-8 (IL-8). All expressed underwent homologous phosphorylation desensitization upon agonist stimulation. When C5a receptor (ET-C5aR) IL-8 (ET-IL-8RA) were cross-phosphorylated by...

Studies of the human m2 (hm2) muscarinic cholinergic receptors (mAChR) have been performed to provide further insights into potential regulation these by isoforms beta-adrenergic receptor kinase (beta ARK). The hm2 mAChR and beta ARK1 ARK2 were individually expressed in, purified from, insect Sf9 cells infected with recombinant baculoviruses. tested as substrates for in vitro using concentrations kinases similar those found intact cells. phosphorylated an agonist-dependent manner 4-5 mol...

Arrestins play an important role in regulating the activity of G protein-coupled receptors rhodopsin and beta 2-adrenergic receptor. Recently, we described expression functional characterization visual arrestin using vitro translation system. Here report beta-arrestin development a direct binding assay to study interaction arrestins with muscarinic cholinergic In translated was found specifically bind purified reconstituted human m2 receptor (hm2 mAChR) agonist- phosphorylation-dependent...

Human leukocyte chemoattractant receptors activate chemotactic and cytotoxic pathways to varying degrees also different G-proteins depending on the receptor cell-type. To determine relationship between G-protein usage biological biochemical responses activated, for chemoattractants formyl peptides (FR), platelet-activating factor (PAFR), leukotriene B4 (BLTR) were transfected into RBL-2H3 cells. Pertussis toxin (Ptx) served as a Gαiinhibitor. These chosen represent spectrum of Gi Ptx had...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRegulation of Human Interleukin-8 Receptor A: Identification a Phosphorylation Site Involved in Modulating FunctionsRicardo M. Richardson, Robert A. DuBose, Hydar Ali, Eric D. Tomhave, Bodduluri Haribabu, and Ralph SnydermanCite this: Biochemistry 1995, 34, 43, 14193–14201Publication Date (Print):October 1, 1995Publication History Published online1 May 2002Published inissue 1 October...

Abstract CXCR2 is a G-protein-coupled receptor (GPCR) that binds the CXC chemokines, CXCL1–3 and CXCL5–8, induces intracellular signals associated with chemotaxis. Many adaptor proteins are actively involved in sequestration, internalization, trafficking of transduction agonist-induced signaling. We have previously shown protein β-arrestin-2 (βarr2) plays crucial role transducing mediated through CXCR2. To further investigate βarr2 on CXCR2-mediated signaling during acute inflammation,...

Abstract Arrestins are adaptor/scaffold proteins that complex with activated and phosphorylated G protein-coupled receptor to terminate protein activation signal transduction. These complexes also mediate downstream signaling, independently of activation. We have previously shown β-arrestin-2 (βarr2) depletion promotes CXCR2-mediated cellular including angiogenesis excisional wound closure. This study was designed investigate the role βarr2 in tumorigenesis using a murine model lung cancer....