scholarly journals C1q-mediated chemotaxis by human neutrophils: involvement of gClqR and G-protein signalling mechanisms

1998 ◽  
Vol 330 (1) ◽  
pp. 247-254 ◽  
Author(s):  
E. A. Leonora LEIGH ◽  
Berhane GHEBREHIWET ◽  
P. S. Tim PERERA ◽  
N. Ian BIRD ◽  
Peter STRONG ◽  
...  
Keyword(s):  
Signal Transduction ◽  
G Protein ◽  
Oxidative Burst ◽  
Binding Protein ◽  
Neutrophil Migration ◽  
Human Neutrophils ◽  
Classical Pathway ◽  
Dependent Manner ◽  
Directed Movement ◽  
G Protein Coupled

C1q, the first component of the classical pathway of the complement system, interacts with various cell types and triggers a variety of cell-specific cellular responses, such as oxidative burst, chemotaxis, phagocytosis, etc. Different biological responses are attributed to the interaction of C1q with more than one putative cell-surface C1q receptor/C1q-binding protein. Previously, it has been shown that C1q-mediated oxidative burst by neutrophils is not linked to G-protein-coupled fMet-Leu-Phe-mediated response. In the present study, we have investigated neutrophil migration brought about by C1q and tried to identify the signal-transduction pathways involved in the chemotactic response. We found that C1q stimulated neutrophil migration in a dose-dependent manner, primarily by enhancing chemotaxis (directed movement) rather than chemokinesis (random movement). This C1q-induced chemotaxis could be abolished by an inhibitor of G-proteins (pertussis toxin) and PtdIns(3,4,5)P3 kinase (wortmannin and LY294002). The collagen tail of C1q appeared to mediate chemotaxis. gC1qR, a C1q-binding protein, has recently been reported to participate in C1q-mediated chemotaxis of murine mast cells and human eosinophils. We observed that gC1qR enhanced binding of free C1q to adherent neutrophils and promoted C1q-mediated chemotaxis of neutrophils by nearly seven-fold. Our results suggests C1q-mediated chemotaxis involves gC1qR as well as G-protein-coupled signal-transduction mechanisms operating downstream to neutrophil chemotaxis.

scholarly journals Hematopoietic Stem and Progenitor Cells Manifest Direct Migration Towards Secreted DEK in a CXCR2- and G Protein Signaling-Dependent Manner

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1196-1196
Author(s):  
Maegan L. Capitano ◽  
Yasser Sammour ◽  
Maureen Legendre ◽  
Scott Cooper ◽  
David Markovitz ◽  
...  
Keyword(s):  
Cell Migration ◽  
G Protein ◽  
Pertussis Toxin ◽  
Conflicts Of Interest ◽  
Neutrophil Migration ◽  
Regulation Of Transcription ◽  
Mouse Bone Marrow ◽  
Dependent Manner ◽  
Hematopoietic Stem ◽  
G Protein Coupled

DEK, a nuclear DNA-binding protein implicated in the regulation of transcription, chromatin architecture, and mRNA processing, is secreted by macrophages and acts as a proinflammatory molecule (Mor-Vanknin et al., 2006, Mol. Cell. Bio., 26: 9484). Recombinant (r)DEK functions as a chemotactic factor attracting neutrophils, CD8+ T lymphocytes and natural killer cells. Few cytokines/growth modulating proteins are known to be chemoattractants for hematopoietic stem (HSC) and progenitor (HPC) cells; stromal cell-derived factor-1 (SDF-1/CXCL12) being the most potent known protein with this capability. To test whether rDEK can serve as a chemotactic agent, transwell assays were performed utilizing lineage negative mouse bone marrow (BM) cells with neutrophils (Ly6G+ cells) as a positive control. Both SDF-1 and DEK induced directed migration of Lin-Sca1+cKit+ (LSK) BM cells at a dose of 100ng/mL, as determined by flow cytometry of input and migrated cells, with no significant migration occurring towards 100ng/mL of IL-8 or MIP-2. All four cytokines induced migration of Ly6G+ neutrophils. After examining the ability of LSK cells to migrate towards various doses of rDEK (0-200ng/mL), it was determined that LSK cells can migrate towards rDEK in a dose dependent manner with maximum chemoattraction potential (~20%) occurring at a dose of DEK equal to or greater than 50ng/mL. A checkerboard assay using LSK cells was performed to determine whether rDEK acted more as a chemotactic (directed cell movement) or a chemokinetic (random migration) agent. Checkerboard analysis demonstrated that DEK acted as a chemotactic molecule. Upon our recent discovery and report that the DEK protein has a Glu-Leu-Arg (ELR) motif, similar to that of CXC chemokines such as IL-8 and binds to the chemokine receptor CXCR2 to regulate hematopoiesis (Capitano et al., 2019, J.C.I. 130: 2555-2570), we hypothesized that DEK may manifest its chemotactic actions through CXCR2, known previously to only bind and mediate the actions of the chemokines IL-8 and MIP-2. To examine this, we first confirmed expression of CXCR2 on the surface of HSC and HPC. Next, to determine if LSK migration towards DEK is dependent upon its ability to signal through CXCR2, LSK cells were pretreated with a neutralizing monoclonal antibody for CXCR2 immediately prior to being placed in a transwell chemotaxis assay utilizing 100ng/mL of rDEK in the bottom chamber. Neutralizing anti-CXCR2 antibodies inhibited migration of both LSK and Ly6G+ cells toward DEK; however, if LSK cells were pretreated with an isotype control or a neutralizing antibody towards CXCR4, migration towards DEK still occurred. To confirm that the neutralizing CXCR2 antibody did not inhibit migration in a non-specific manner, transwell assays were performed examining LSK cell migration towards SDF-1, IL-8, and MIP-2. LSK cells were still able to migrate towards SDF-1 except when CXCR4 was neutralized. No migration of LSK cells was observed when IL-8 or MIP-2 was utilized. When Ly6G+ neutrophils were used, CXCR2 neutralizing antibodies blocked migration of the Ly6G+ neutrophils towards DEK, IL-8 and MIP-2. Neutralizing CXCR4 only blocked Ly6G+ neutrophil migration towards SDF-1. CXCR2 is a G protein-coupled receptor and this interaction can be blocked using pertussis toxin which prevents G proteins from interacting with G protein-coupled receptors thus interfering with receptor signaling. Pretreatment of LSK cells with pertussis toxin significantly inhibited the migration of LSK cells towards DEK and SDF-1. To determine if DEK and SDF-1 could inhibit one another, checkboard assays were performed where either different concentrations of DEK was used in the top well and different concentrations of SDF-1 was used on the bottom. Starting at 100ng/mL, DEK in the top well inhibited LSK cell migration towards SDF-1. However, when SDF-1 was in the top well, regardless of the SDF-1 dose, SDF-1 always inhibited LSK cell migration towards DEK. These data suggest that DEK acts as a chemotactic agent for HSC and HPC in vitro but is not as strong of a signaling protein for migration when competing against SDF-1. Thus, DEK may be involved as a compensatory chemotactic agent for HSCs and HPCs, especially under certain inflammatory conditions and when SDF-1 signaling is reduced. Disclosures No relevant conflicts of interest to declare.

scholarly journals The small GTP-binding protein, Rhes, regulates signal transduction from G protein-coupled receptors

Oncogene ◽  
2004 ◽  
Vol 23 (2) ◽  
pp. 559-568 ◽  
Author(s):  
Pierfrancesco Vargiu ◽  
Ricardo De Abajo ◽  
Juan Antonio Garcia-Ranea ◽  
Alfonso Valencia ◽  
Pilar Santisteban ◽  
...  
Keyword(s):  
Signal Transduction ◽  
G Protein ◽  
Binding Protein ◽  
G Protein Coupled Receptors ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
G Protein Coupled

scholarly journals The G Protein-Coupled Receptor Kinases (GRKs) in Chemokine Receptor-Mediated Immune Cell Migration: From Molecular Cues to Physiopathology

Cells ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 75
Author(s):  
Marta Laganà ◽  
Géraldine Schlecht-Louf ◽  
Françoise Bachelerie
Keyword(s):  
G Protein ◽  
Chemokine Receptor ◽  
Immune Cell ◽  
Neutrophil Migration ◽  
G Protein Coupled Receptor ◽  
Receptor Kinases ◽  
Immune Cell Migration ◽  
And Migration ◽  
G Protein Coupled ◽  
Gpcr Desensitization

Although G protein-coupled receptor kinases (GRKs) have long been known to regulate G protein-coupled receptor (GPCR) desensitization, their more recently characterized functions as scaffolds and signalling adapters underscore that this small family of proteins governs a larger array of physiological functions than originally suspected. This review explores how GRKs contribute to the complex signalling networks involved in the migration of immune cells along chemokine gradients sensed by cell surface GPCRs. We outline emerging evidence indicating that the coordinated docking of several GRKs on an active chemokine receptor determines a specific receptor phosphorylation barcode that will translate into distinct signalling and migration outcomes. The guidance cues for neutrophil migration are emphasized based on several alterations affecting GRKs or GPCRs reported to be involved in pathological conditions.

scholarly journals Every Detail Matters. That Is, How the Interaction between Gα Proteins and Membrane Affects Their Function

Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 222
Author(s):  
Agnieszka Polit ◽  
Paweł Mystek ◽  
Ewa Błasiak
Keyword(s):  
Signal Transduction ◽  
G Protein ◽  
G Proteins ◽  
Lipid Membranes ◽  
Signaling Proteins ◽  
Heterotrimeric G Proteins ◽  
Membrane Attachment ◽  
The Individual ◽  
Multicellular Organisms ◽  
G Protein Coupled

In highly organized multicellular organisms such as humans, the functions of an individual cell are dependent on signal transduction through G protein-coupled receptors (GPCRs) and subsequently heterotrimeric G proteins. As most of the elements belonging to the signal transduction system are bound to lipid membranes, researchers are showing increasing interest in studying the accompanying protein–lipid interactions, which have been demonstrated to not only provide the environment but also regulate proper and efficient signal transduction. The mode of interaction between the cell membrane and G proteins is well known. Despite this, the recognition mechanisms at the molecular level and how the individual G protein-membrane attachment signals are interrelated in the process of the complex control of membrane targeting of G proteins remain unelucidated. This review focuses on the mechanisms by which mammalian Gα subunits of G proteins interact with lipids and the factors responsible for the specificity of membrane association. We summarize recent data on how these signaling proteins are precisely targeted to a specific site in the membrane region by introducing well-defined modifications as well as through the presence of polybasic regions within these proteins and interactions with other components of the heterocomplex.

Caffeine does not inhibit substance P-evoked intracellular Ca2+ mobilization in rat salivary acinar cells

1999 ◽  
Vol 276 (4) ◽  
pp. C915-C922 ◽  
Author(s):  
J. T. Seo ◽  
H. Sugiya ◽  
S. I. Lee ◽  
M. C. Steward ◽  
A. C. Elliott
Keyword(s):  
Signal Transduction ◽  
Substance P ◽  
G Protein ◽  
Acinar Cells ◽  
Inhibitory Effect ◽  
Structural Motif ◽  
Stimulus Response ◽  
Inhibit Substance ◽  
Prior Application ◽  
G Protein Coupled

We used the Ca2+-sensitive fluorescent dye fura 2, together with measurements of intracellulard- myo-inositol 1,4,5-trisphosphate [Ins(1,4,5) P 3], to assess the inhibitory effects of caffeine on signal transduction via G protein-coupled receptor pathways in isolated rat mandibular salivary acinar cells. ACh, norepinephrine (NE), and substance P (SP) all evoked substantial increases in the intracellular free Ca2+ concentration ([Ca2+]i). Responses to ACh and NE were markedly inhibited by prior application of 20 mM caffeine. The inhibitory effect of caffeine was not reproduced by phosphodiesterase inhibition with IBMX or addition of cell-permeant dibutyryl cAMP. In contrast to the ACh and NE responses, the [Ca2+]iresponse to SP was unaffected by caffeine. Despite this, SP and ACh appeared to mobilize Ca2+ from a common intracellular pool. Measurements of agonist-induced changes in Ins(1,4,5) P 3levels confirmed that caffeine inhibited the stimulus-response coupling pathway at a point before Ins(1,4,5) P 3generation. Caffeine did not, however, inhibit [Ca2+]iresponses evoked by direct activation of G proteins with 40 mM F−. These data show that caffeine inhibits G protein-coupled signal transduction in these cells at some element that is common to the muscarinic and α-adrenergic signaling pathways but is not shared by the SP signaling pathway. We suggest that this element might be a specific structural motif on the G protein-coupled muscarinic and α-adrenergic receptors.

scholarly journals Opiates Transdeactivate Chemokine Receptors: δ and μ Opiate Receptor–mediated Heterologous Desensitization

1998 ◽  
Vol 188 (2) ◽  
pp. 317-325 ◽  
Author(s):  
M.C. Grimm ◽  
A. Ben-Baruch ◽  
D.D. Taub ◽  
O.M.Z. Howard ◽  
J.H. Resau ◽  
...  
Keyword(s):  
G Protein ◽  
Host Defense ◽  
Chemokine Receptors ◽  
Opiate Receptors ◽  
Calcium Flux ◽  
Human Neutrophils ◽  
Endogenous Opioid ◽  
Opiate Abuse ◽  
Heterologous Desensitization ◽  
G Protein Coupled

An intact chemotactic response is vital for leukocyte trafficking and host defense. Opiates are known to exert a number of immunomodulating effects in vitro and in vivo, and we sought to determine whether they were capable of inhibiting chemokine-induced directional migration of human leukocytes, and if so, to ascertain the mechanism involved. The endogenous opioid met-enkephalin induced monocyte chemotaxis in a pertussis toxin–sensitive manner. Met-enkephalin, as well as morphine, inhibited IL-8–induced chemotaxis of human neutrophils and macrophage inflammatory protein (MIP)-1α, regulated upon activation, normal T expressed and secreted (RANTES), and monocyte chemoattractant protein 1, but not MIP-1β–induced chemotaxis of human monocytes. This inhibition of chemotaxis was mediated by δ and μ but not κ G protein–coupled opiate receptors. Calcium flux induced by chemokines was unaffected by met-enkephalin pretreatment. Unlike other opiate-induced changes in leukocyte function, the inhibition of chemotaxis was not mediated by nitric oxide. Opiates induced phosphorylation of the chemokine receptors CXCR1 and CXCR2, but neither induced internalization of chemokine receptors nor perturbed chemokine binding. Thus, inhibition of chemokine-induced chemotaxis by opiates is due to heterologous desensitization through phosphorylation of chemokine receptors. This may contribute to the defects in host defense seen with opiate abuse and has important implications for immunomodulation induced by several endogenous neuropeptides which act through G protein–coupled receptors.

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