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Cheng H, Guo P, Su T, Jiang C, Zhu Z, Wei W, Zhang L, Wang Q. G protein-coupled receptor kinase type 2 and β-arrestin2: Key players in immune cell functions and inflammation. Cell Signal 2022; 95:110337. [DOI: 10.1016/j.cellsig.2022.110337] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 04/15/2022] [Accepted: 04/15/2022] [Indexed: 02/07/2023]
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2
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Cheng J, Lucas PC, McAllister-Lucas LM. Canonical and Non-Canonical Roles of GRK2 in Lymphocytes. Cells 2021; 10:cells10020307. [PMID: 33546162 PMCID: PMC7913175 DOI: 10.3390/cells10020307] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 12/18/2022] Open
Abstract
G protein-coupled receptor kinase 2 (GRK2) is emerging as a key integrative signaling node in a variety of biological processes ranging from cell growth and proliferation to migration and chemotaxis. As such, GRK2 is now implicated as playing a role in the molecular pathogenesis of a broad group of diseases including heart failure, cancer, depression, neurodegenerative disease, and others. In addition to its long-known canonical role in the phosphorylation and desensitization of G protein-coupled receptors (GPCRs), recent studies have shown that GRK2 also modulates a diverse array of other molecular processes via newly identified GRK2 kinase substrates and via a growing number of protein-protein interaction binding partners. GRK2 belongs to the 7-member GRK family. It is a multidomain protein containing a specific N-terminal region (referred to as αN), followed by a regulator of G protein signaling homology (RH) domain, an AGC (Protein kinase A, G, C serine/threonine kinase family) kinase domain, and a C-terminal pleckstrin homology (PH) domain. GPCRs mediate the activity of many regulators of the immune system such as chemokines and leukotrienes, and thus GRK proteins may play key roles in modulating the lymphocyte response to these factors. As one of the predominant GRK family members expressed in immune cells, GRK2's canonical and noncanonical actions play an especially significant role in normal immune cell function as well as in the development and progression of disorders of the immune system. This review summarizes our current state of knowledge of the roles of GRK2 in lymphocytes. We highlight the diverse functions of GRK2 and discuss how ongoing investigation of GRK2 in lymphocytes may inform the development of new therapies for diseases associated with lymphocyte dysregulation.
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Affiliation(s)
- Jing Cheng
- Division of Hematology-Oncology, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA;
- Correspondence:
| | - Peter C. Lucas
- Divisions of Molecular Genomic Pathology and Experimental Pathology, Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA;
- UPMC Hillman Cancer Center, Pittsburgh, PA 15232, USA
| | - Linda M. McAllister-Lucas
- Division of Hematology-Oncology, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA;
- UPMC Hillman Cancer Center, Pittsburgh, PA 15232, USA
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3
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Penela P, Ribas C, Sánchez-Madrid F, Mayor F. G protein-coupled receptor kinase 2 (GRK2) as a multifunctional signaling hub. Cell Mol Life Sci 2019; 76:4423-4446. [PMID: 31432234 PMCID: PMC6841920 DOI: 10.1007/s00018-019-03274-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 08/06/2019] [Accepted: 08/12/2019] [Indexed: 12/18/2022]
Abstract
Accumulating evidence indicates that G protein-coupled receptor kinase 2 (GRK2) is a versatile protein that acts as a signaling hub by modulating G protein-coupled receptor (GPCR) signaling and also via phosphorylation or scaffolding interactions with an extensive number of non-GPCR cellular partners. GRK2 multifunctionality arises from its multidomain structure and from complex mechanisms of regulation of its expression levels, activity, and localization within the cell, what allows the precise spatio-temporal shaping of GRK2 targets. A better understanding of the GRK2 interactome and its modulation mechanisms is helping to identify the GRK2-interacting proteins and its substrates involved in the participation of this kinase in different cellular processes and pathophysiological contexts.
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Affiliation(s)
- Petronila Penela
- Departamento de Biología Molecular, Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, C/Nicolás Cabrera 1, 28049, Madrid, Spain
- Instituto de Investigación Sanitaria La Princesa, 28006, Madrid, Spain
- CIBER de Enfermedades Cardiovasculares, ISCIII (CIBERCV), 28029, Madrid, Spain
| | - Catalina Ribas
- Departamento de Biología Molecular, Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, C/Nicolás Cabrera 1, 28049, Madrid, Spain
- Instituto de Investigación Sanitaria La Princesa, 28006, Madrid, Spain
- CIBER de Enfermedades Cardiovasculares, ISCIII (CIBERCV), 28029, Madrid, Spain
| | - Francisco Sánchez-Madrid
- Instituto de Investigación Sanitaria La Princesa, 28006, Madrid, Spain
- CIBER de Enfermedades Cardiovasculares, ISCIII (CIBERCV), 28029, Madrid, Spain
- Cell-Cell Communication Laboratory, Vascular Pathophysiology Area, Centro Nacional Investigaciones Cardiovasculares (CNIC), 28029, Madrid, Spain
| | - Federico Mayor
- Departamento de Biología Molecular, Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, C/Nicolás Cabrera 1, 28049, Madrid, Spain.
- Instituto de Investigación Sanitaria La Princesa, 28006, Madrid, Spain.
- CIBER de Enfermedades Cardiovasculares, ISCIII (CIBERCV), 28029, Madrid, Spain.
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Dinkel BA, Kremer KN, Rollins MR, Medlyn MJ, Hedin KE. GRK2 mediates TCR-induced transactivation of CXCR4 and TCR-CXCR4 complex formation that drives PI3Kγ/PREX1 signaling and T cell cytokine secretion. J Biol Chem 2018; 293:14022-14039. [PMID: 30018141 DOI: 10.1074/jbc.ra118.003097] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 07/05/2018] [Indexed: 12/12/2022] Open
Abstract
The immune system includes abundant examples of biologically-relevant cross-regulation of signaling pathways by the T cell antigen receptor (TCR) and the G protein-coupled chemokine receptor, CXCR4. TCR ligation induces transactivation of CXCR4 and TCR-CXCR4 complex formation, permitting the TCR to signal via CXCR4 to activate a phosphatidylinositol 3,4,5-trisphosphate-dependent Rac exchanger 1 protein (PREX1)-dependent signaling pathway that drives robust cytokine secretion by T cells. To understand this receptor heterodimer and its regulation, we characterized the molecular mechanisms required for TCR-mediated TCR-CXCR4 complex formation. We found that the cytoplasmic C-terminal domain of CXCR4 and specifically phosphorylation of Ser-339 within this region were required for TCR-CXCR4 complex formation. Interestingly, siRNA-mediated depletion of G protein-coupled receptor kinase-2 (GRK2) or inhibition by the GRK2-specific inhibitor, paroxetine, inhibited TCR-induced phosphorylation of CXCR4-Ser-339 and TCR-CXCR4 complex formation. Either GRK2 siRNA or paroxetine treatment of human T cells significantly reduced T cell cytokine production. Upstream, TCR-activated tyrosine kinases caused inducible tyrosine phosphorylation of GRK2 and were required for the GRK2-dependent events of CXCR4-Ser-339 phosphorylation and TCR-CXCR4 complex formation. Downstream of TCR-CXCR4 complex formation, we found that GRK2 and phosphatidylinositol 3-kinase γ (PI3Kγ) were required for TCR-stimulated membrane recruitment of PREX1 and for stabilization of cytokine mRNAs and robust cytokine secretion. Together, our results identify a novel role for GRK2 as a target of TCR signaling that is responsible for TCR-induced transactivation of CXCR4 and TCR-CXCR4 complex formation that signals via PI3Kγ/PREX1 to mediate cytokine production. Therapeutic regulation of GRK2 or PI3Kγ may therefore be useful for limiting cytokines produced by T cell malignancies or autoimmune diseases.
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Affiliation(s)
- Brittney A Dinkel
- From the Mayo IMM Ph.D. Training Program, Mayo Clinic Graduate School of Biomedical Sciences, and.,Department of Immunology, Mayo Clinic College of Medicine and Science, Mayo Clinic, Rochester, Minnesota 55905
| | - Kimberly N Kremer
- Department of Immunology, Mayo Clinic College of Medicine and Science, Mayo Clinic, Rochester, Minnesota 55905
| | - Meagan R Rollins
- Department of Immunology, Mayo Clinic College of Medicine and Science, Mayo Clinic, Rochester, Minnesota 55905
| | - Michael J Medlyn
- Department of Immunology, Mayo Clinic College of Medicine and Science, Mayo Clinic, Rochester, Minnesota 55905
| | - Karen E Hedin
- Department of Immunology, Mayo Clinic College of Medicine and Science, Mayo Clinic, Rochester, Minnesota 55905
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Abstract
G protein-coupled receptor kinases (GRKs) are classically known for their role in regulating the activity of the largest known class of membrane receptors, which influence diverse biological processes in every cell type in the human body. As researchers have tried to uncover how this family of kinases, containing only 7 members, achieves selective and coordinated control of receptors, they have uncovered a growing number of noncanonical activities for these kinases. These activities include phosphorylation of nonreceptor targets and kinase-independent molecular interactions. In particular, GRK2, GRK3, and GRK5 are the predominant members expressed in the heart. Their canonical and noncanonical actions within cardiac and other tissues have significant implications for cardiovascular function in healthy animals and for the development and progression of disease. This review summarizes what is currently known regarding the activity of these kinases, and particularly the role of GRK2 and GRK5 in the molecular alterations that occur during heart failure. This review further highlights areas of GRK regulation that remain poorly understood and how they may represent novel targets for therapeutic development.
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Bellinger DL, Lorton D. Sympathetic Nerve Hyperactivity in the Spleen: Causal for Nonpathogenic-Driven Chronic Immune-Mediated Inflammatory Diseases (IMIDs)? Int J Mol Sci 2018; 19:ijms19041188. [PMID: 29652832 PMCID: PMC5979464 DOI: 10.3390/ijms19041188] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 04/05/2018] [Accepted: 04/05/2018] [Indexed: 12/21/2022] Open
Abstract
Immune-Mediated Inflammatory Diseases (IMIDs) is a descriptive term coined for an eclectic group of diseases or conditions that share common inflammatory pathways, and for which there is no definitive etiology. IMIDs affect the elderly most severely, with many older individuals having two or more IMIDs. These diseases include, but are not limited to, type-1 diabetes, obesity, hypertension, chronic pulmonary disease, coronary heart disease, inflammatory bowel disease, and autoimmunity, such as rheumatoid arthritis (RA), Sjőgren's syndrome, systemic lupus erythematosus, psoriasis, psoriatic arthritis, and multiple sclerosis. These diseases are ostensibly unrelated mechanistically, but increase in frequency with age and share chronic systemic inflammation, implicating major roles for the spleen. Chronic systemic and regional inflammation underlies the disease manifestations of IMIDs. Regional inflammation and immune dysfunction promotes targeted end organ tissue damage, whereas systemic inflammation increases morbidity and mortality by affecting multiple organ systems. Chronic inflammation and skewed dysregulated cell-mediated immune responses drive many of these age-related medical disorders. IMIDs are commonly autoimmune-mediated or suspected to be autoimmune diseases. Another shared feature is dysregulation of the autonomic nervous system and hypothalamic pituitary adrenal (HPA) axis. Here, we focus on dysautonomia. In many IMIDs, dysautonomia manifests as an imbalance in activity/reactivity of the sympathetic and parasympathetic divisions of the autonomic nervous system (ANS). These major autonomic pathways are essential for allostasis of the immune system, and regulating inflammatory processes and innate and adaptive immunity. Pathology in ANS is a hallmark and causal feature of all IMIDs. Chronic systemic inflammation comorbid with stress pathway dysregulation implicate neural-immune cross-talk in the etiology and pathophysiology of IMIDs. Using a rodent model of inflammatory arthritis as an IMID model, we report disease-specific maladaptive changes in β₂-adrenergic receptor (AR) signaling from protein kinase A (PKA) to mitogen activated protein kinase (MAPK) pathways in the spleen. Beta₂-AR signal "shutdown" in the spleen and switching from PKA to G-coupled protein receptor kinase (GRK) pathways in lymph node cells drives inflammation and disease advancement. Based on these findings and the existing literature in other IMIDs, we present and discuss relevant literature that support the hypothesis that unresolvable immune stimulation from chronic inflammation leads to a maladaptive disease-inducing and perpetuating sympathetic response in an attempt to maintain allostasis. Since the role of sympathetic dysfunction in IMIDs is best studied in RA and rodent models of RA, this IMID is the primary one used to evaluate data relevant to our hypothesis. Here, we review the relevant literature and discuss sympathetic dysfunction as a significant contributor to the pathophysiology of IMIDs, and then discuss a novel target for treatment. Based on our findings in inflammatory arthritis and our understanding of common inflammatory process that are used by the immune system across all IMIDs, novel strategies to restore SNS homeostasis are expected to provide safe, cost-effective approaches to treat IMIDs, lower comorbidities, and increase longevity.
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Affiliation(s)
- Denise L Bellinger
- Department of Pathology and Human Anatomy, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA.
| | - Dianne Lorton
- College of Arts and Sciences, Kent State University, Kent, OH 44304, USA.
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7
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Barnea ER, Kirk D, Todorova K, McElhinney J, Hayrabedyan S, Fernández N. PIF direct immune regulation: Blocks mitogen-activated PBMCs proliferation, promotes TH2/TH1 bias, independent of Ca2+. Immunobiology 2015; 220:865-75. [DOI: 10.1016/j.imbio.2015.01.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 01/19/2015] [Accepted: 01/22/2015] [Indexed: 10/24/2022]
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8
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Mikucki ME, Fisher DT, Matsuzaki J, Skitzki JJ, Gaulin NB, Muhitch JB, Ku AW, Frelinger JG, Odunsi K, Gajewski TF, Luster AD, Evans SS. Non-redundant requirement for CXCR3 signalling during tumoricidal T-cell trafficking across tumour vascular checkpoints. Nat Commun 2015; 6:7458. [PMID: 26109379 PMCID: PMC4605273 DOI: 10.1038/ncomms8458] [Citation(s) in RCA: 329] [Impact Index Per Article: 36.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2015] [Accepted: 05/12/2015] [Indexed: 12/18/2022] Open
Abstract
T-cell trafficking at vascular sites has emerged as a key step in antitumour immunity. Chemokines are credited with guiding the multistep recruitment of CD8(+) T cells across tumour vessels. However, the multiplicity of chemokines within tumours has obscured the contributions of individual chemokine receptor/chemokine pairs to this process. Moreover, recent studies have challenged whether T cells require chemokine receptor signalling at effector sites. Here we investigate the hierarchy of chemokine receptor requirements during T-cell trafficking to murine and human melanoma. These studies reveal a non-redundant role for Gαi-coupled CXCR3 in stabilizing intravascular adhesion and extravasation of adoptively transferred CD8(+) effectors that is indispensable for therapeutic efficacy. In contrast, functional CCR2 and CCR5 on CD8(+) effectors fail to support trafficking despite the presence of intratumoral cognate chemokines. Taken together, these studies identify CXCR3-mediated trafficking at the tumour vascular interface as a critical checkpoint to effective T-cell-based cancer immunotherapy.
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MESH Headings
- Adoptive Transfer
- Animals
- CD8-Positive T-Lymphocytes/physiology
- Cell Movement
- Female
- Gene Expression Regulation
- Melanoma/metabolism
- Melanoma, Experimental/genetics
- Melanoma, Experimental/metabolism
- Mice
- Mice, Knockout
- Mice, Transgenic
- Neoplasms/blood supply
- Ovalbumin/genetics
- Ovalbumin/metabolism
- Receptors, CCR2/genetics
- Receptors, CCR2/metabolism
- Receptors, CCR5/genetics
- Receptors, CCR5/metabolism
- Receptors, CXCR3/genetics
- Receptors, CXCR3/metabolism
- Signal Transduction/physiology
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Affiliation(s)
- ME Mikucki
- Department of Immunology, Roswell Park Cancer Institute, Buffalo, NY
| | - DT Fisher
- Department of Immunology, Roswell Park Cancer Institute, Buffalo, NY
| | - J Matsuzaki
- Center for Immunotherapy, Roswell Park Cancer Institute, Buffalo, NY
| | - JJ Skitzki
- Department of Immunology, Roswell Park Cancer Institute, Buffalo, NY
- Department of Surgical Oncology, Roswell Park Cancer Institute, Buffalo, NY
| | - NB Gaulin
- Department of Immunology, Roswell Park Cancer Institute, Buffalo, NY
| | - JB Muhitch
- Department of Immunology, Roswell Park Cancer Institute, Buffalo, NY
| | - AW Ku
- Department of Immunology, Roswell Park Cancer Institute, Buffalo, NY
| | - JG Frelinger
- Department of Microbiology and Immunology, University of Rochester Medical Center and the Wilmot Cancer Center, Rochester, NY
| | - K Odunsi
- Center for Immunotherapy, Roswell Park Cancer Institute, Buffalo, NY
- Department of Gynecologic Oncology, Roswell Park Cancer Institute, Buffalo, NY
| | - TF Gajewski
- Department of Medicine, University of Chicago
- Department of Pathology, University of Chicago
- Comprehensive Cancer Center and Committee on Immunology, University of Chicago
| | - AD Luster
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy and Immunology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - SS Evans
- Department of Immunology, Roswell Park Cancer Institute, Buffalo, NY
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Sato PY, Chuprun JK, Schwartz M, Koch WJ. The evolving impact of g protein-coupled receptor kinases in cardiac health and disease. Physiol Rev 2015; 95:377-404. [PMID: 25834229 PMCID: PMC4551214 DOI: 10.1152/physrev.00015.2014] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are important regulators of various cellular functions via activation of intracellular signaling events. Active GPCR signaling is shut down by GPCR kinases (GRKs) and subsequent β-arrestin-mediated mechanisms including phosphorylation, internalization, and either receptor degradation or resensitization. The seven-member GRK family varies in their structural composition, cellular localization, function, and mechanism of action (see sect. II). Here, we focus our attention on GRKs in particular canonical and novel roles of the GRKs found in the cardiovascular system (see sects. III and IV). Paramount to overall cardiac function is GPCR-mediated signaling provided by the adrenergic system. Overstimulation of the adrenergic system has been highly implicated in various etiologies of cardiovascular disease including hypertension and heart failure. GRKs acting downstream of heightened adrenergic signaling appear to be key players in cardiac homeostasis and disease progression, and herein we review the current data on GRKs related to cardiac disease and discuss their potential in the development of novel therapeutic strategies in cardiac diseases including heart failure.
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Affiliation(s)
- Priscila Y Sato
- Center for Translational Medicine and Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania; and Advanced Institutes of Convergence Technology, Suwon, South Korea
| | - J Kurt Chuprun
- Center for Translational Medicine and Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania; and Advanced Institutes of Convergence Technology, Suwon, South Korea
| | - Mathew Schwartz
- Center for Translational Medicine and Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania; and Advanced Institutes of Convergence Technology, Suwon, South Korea
| | - Walter J Koch
- Center for Translational Medicine and Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania; and Advanced Institutes of Convergence Technology, Suwon, South Korea
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Ohashi W, Hattori Y. [GRK2 as a potential therapeutic target for septic ARDS]. Nihon Yakurigaku Zasshi 2015; 145:122-8. [PMID: 25765493 DOI: 10.1254/fpj.145.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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11
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Molecular mechanisms underlying β-adrenergic receptor-mediated cross-talk between sympathetic neurons and immune cells. Int J Mol Sci 2015; 16:5635-65. [PMID: 25768345 PMCID: PMC4394497 DOI: 10.3390/ijms16035635] [Citation(s) in RCA: 118] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 02/13/2015] [Accepted: 03/04/2015] [Indexed: 01/01/2023] Open
Abstract
Cross-talk between the sympathetic nervous system (SNS) and immune system is vital for health and well-being. Infection, tissue injury and inflammation raise firing rates of sympathetic nerves, increasing their release of norepinephrine (NE) in lymphoid organs and tissues. NE stimulation of β2-adrenergic receptors (ARs) in immune cells activates the cAMP-protein kinase A (PKA) intracellular signaling pathway, a pathway that interfaces with other signaling pathways that regulate proliferation, differentiation, maturation and effector functions in immune cells. Immune-SNS cross-talk is required to maintain homeostasis under normal conditions, to develop an immune response of appropriate magnitude after injury or immune challenge, and subsequently restore homeostasis. Typically, β2-AR-induced cAMP is immunosuppressive. However, many studies report actions of β2-AR stimulation in immune cells that are inconsistent with typical cAMP-PKA signal transduction. Research during the last decade in non-immune organs, has unveiled novel alternative signaling mechanisms induced by β2-AR activation, such as a signaling switch from cAMP-PKA to mitogen-activated protein kinase (MAPK) pathways. If alternative signaling occurs in immune cells, it may explain inconsistent findings of sympathetic regulation of immune function. Here, we review β2-AR signaling, assess the available evidence for alternative signaling in immune cells, and provide insight into the circumstances necessary for "signal switching" in immune cells.
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12
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Anastasaki C, Gutmann DH. Neuronal NF1/RAS regulation of cyclic AMP requires atypical PKC activation. Hum Mol Genet 2014; 23:6712-21. [PMID: 25070947 DOI: 10.1093/hmg/ddu389] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Neurofibromatosis type 1 (NF1) is a common neurodevelopmental disorder in which affected individuals are prone to learning, attention and behavioral problems. Previous studies in mice and flies have yielded conflicting results regarding the specific effector pathways responsible for NF1 protein (neurofibromin) regulation of neuronal function, with both cyclic AMP (cAMP)- and RAS-dependent mechanisms described. Herein, we leverage a combination of induced pluripotent stem cell-derived NF1 patient neural progenitor cells and Nf1 genetically engineered mice to establish, for the first time, that neurofibromin regulation of cAMP requires RAS activation in human and mouse neurons. However, instead of involving RAS-mediated MEK/AKT signaling, RAS regulation of cAMP homeostasis operates through the activation of atypical protein kinase C zeta, leading to GRK2-driven Gαs inactivation. These findings reveal a novel mechanism by which RAS can regulate cAMP levels in the mammalian brain.
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Affiliation(s)
- Corina Anastasaki
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - David H Gutmann
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
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13
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Daniele S, Trincavelli ML, Fumagalli M, Zappelli E, Lecca D, Bonfanti E, Campiglia P, Abbracchio MP, Martini C. Does GRK–β arrestin machinery work as a “switch on” for GPR17-mediated activation of intracellular signaling pathways? Cell Signal 2014; 26:1310-25. [DOI: 10.1016/j.cellsig.2014.02.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 02/27/2014] [Accepted: 02/27/2014] [Indexed: 12/13/2022]
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14
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Kickler K, Maltby K, Ni Choileain S, Stephen J, Wright S, Hafler DA, Jabbour HN, Astier AL. Prostaglandin E2 affects T cell responses through modulation of CD46 expression. THE JOURNAL OF IMMUNOLOGY 2012; 188:5303-10. [PMID: 22544928 DOI: 10.4049/jimmunol.1103090] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The ubiquitous protein CD46, a regulator of complement activity, promotes T cell activation and differentiation toward a regulatory Tr1-like phenotype. The CD46-mediated differentiation pathway is defective in several chronic inflammatory diseases, underlying the importance of CD46 in controlling T cell function and the need to understand its regulatory mechanisms. Using an RNA interference-based screening approach in primary T cells, we have identified that two members of the G protein-coupled receptor kinases were involved in regulating CD46 expression at the surface of activated cells. We have investigated the role of PGE(2), which binds to the E-prostanoid family of G protein-coupled receptors through four subtypes of receptors called EP 1-4, in the regulation of CD46 expression and function. Conflicting roles of PGE(2) in T cell functions have been reported, and the reasons for these apparent discrepancies are not well understood. We show that addition of PGE(2) strongly downregulates CD46 expression in activated T cells. Moreover, PGE(2) differentially affects T cell activation, cytokine production, and phenotype depending on the activation signals received by the T cells. This was correlated with a distinct pattern of the PGE(2) receptors expressed, with EP4 being preferentially induced by CD46 activation. Indeed, addition of an EP4 antagonist could reverse the effects observed on cytokine production after CD46 costimulation. These data demonstrate a novel role of the PGE(2)-EP4 axis in CD46 functions, which might at least partly explain the diverse roles of PGE(2) in T cell functions.
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Affiliation(s)
- Karoline Kickler
- Centre for Inflammation Research, University of Edinburgh, Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom
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15
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Migration of Th1 lymphocytes is regulated by CD152 (CTLA-4)-mediated signaling via PI3 kinase-dependent Akt activation. PLoS One 2012; 7:e31391. [PMID: 22412835 PMCID: PMC3295805 DOI: 10.1371/journal.pone.0031391] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 01/06/2012] [Indexed: 11/20/2022] Open
Abstract
Efficient adaptive immune responses require the localization of T lymphocytes in secondary lymphoid organs and inflamed tissues. To achieve correct localization of T lymphocytes, the migration of these cells is initiated and directed by adhesion molecules and chemokines. It has recently been shown that the inhibitory surface molecule CD152 (CTLA-4) initiates Th cell migration, but the molecular mechanism underlying this effect remains to be elucidated. Using CD4 T lymphocytes derived from OVA-specific TCR transgenic CD152-deficient and CD152-competent mice, we demonstrate that chemokine-triggered signal transduction is differentially regulated by CD152 via phosphoinositide 3-kinase (PI3K)-dependent activation of protein kinase B (PKB/Akt). In the presence of CD152 signaling, the chemoattractant CCL4 selectively induces the full activation of Akt via phosphorylation at threonine 308 and serine 473 in pro-inflammatory Th lymphocytes expressing the cognate chemokine receptor CCR5. Akt signals lead to cytoskeleton rearrangements, which are indispensable for migration. Therefore, this novel Akt-modulating function of CD152 signals affecting T cell migration demonstrates that boosting CD152 or its down-stream signal transduction could aid therapies aimed at sensitizing T lymphocytes for optimal migration, thus contributing to a precise and effective immune response.
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16
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Neural pathways in allergic inflammation. J Allergy (Cairo) 2011; 2010:491928. [PMID: 21331366 PMCID: PMC3038426 DOI: 10.1155/2010/491928] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2010] [Revised: 11/30/2010] [Accepted: 12/08/2010] [Indexed: 12/20/2022] Open
Abstract
Allergy is on the rise worldwide. Asthma, food allergy, dermatitis, and systemic anaphylaxis are amongst the most common allergic diseases. The association between allergy and altered behavior patterns has long been recognized. The molecular and cellular pathways in the bidirectional interactions of nervous and immune systems are now starting to be elucidated. In this paper, we outline the consequences of allergic diseases, especially food allergy and asthma, on behavior and neural activity and on the neural modulation of allergic responses.
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Patial S, Saini Y, Parvataneni S, Appledorn DM, Dorn GW, Lapres JJ, Amalfitano A, Senagore P, Parameswaran N. Myeloid-specific GPCR kinase-2 negatively regulates NF-κB1p105-ERK pathway and limits endotoxemic shock in mice. J Cell Physiol 2011; 226:627-37. [PMID: 20717897 DOI: 10.1002/jcp.22384] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
G-protein-coupled receptor kinase 2 (GRK2) is a member of a kinase family originally discovered for its role in the phosphorylation and desensitization of G-protein-coupled receptors. It is expressed in high levels in myeloid cells and its levels are altered in many inflammatory disorders including sepsis. To address the physiological role of myeloid cell-specific GRK2 in inflammation, we generated mice bearing GRK2 deletion in myeloid cells (GRK2▵mye). GRK2▵mye mice exhibited exaggerated inflammatory cytokine/chemokine production, and organ injury in response to lipopolysaccharide (LPS, a TLR4 ligand) when compared to wild-type littermates (GRK2fl/fl). Consistent with this, peritoneal macrophages from GRK2▵mye mice showed enhanced inflammatory cytokine levels when stimulated with LPS. Our results further identify TLR4-induced NF-κB1p105-ERK pathway to be selectively regulated by GRK2. LPS-induced activation of NF-κB1p105-MEK-ERK pathway is significantly enhanced in the GRK2▵mye macrophages compared to GRK2fl/fl cells and importantly, inhibition of the p105 and ERK pathways in the GRK2▵mye macrophages, limits the enhanced production of LPS-induced cytokines/chemokines. Taken together, our studies reveal previously undescribed negative regulatory role for GRK2 in TLR4-induced p105-ERK pathway as well as in the consequent inflammatory cytokine/chemokine production and endotoxemia in mice.
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Affiliation(s)
- Sonika Patial
- Department of Physiology and Division of Pathology, Michigan State University, East Lansing, Michigan 48824, USA
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Agüero J, Almenar L, D'Ocon P, Oliver E, Montó F, Rueda J, Vicente D, Martínez-Dolz L, Salvador A. Myocardial and peripheral lymphocytic transcriptomic dissociation of beta-adrenoceptors and G protein-coupled receptor kinases in heart transplantation. J Heart Lung Transplant 2009; 28:1166-71. [PMID: 19782607 DOI: 10.1016/j.healun.2009.06.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2009] [Revised: 06/06/2009] [Accepted: 06/06/2009] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND The genetic expression of adrenergic receptors plays an important pathophysiologic role in heart failure. G protein-coupled receptor kinases (GRKs) desensitize the beta-receptor to catecholaminergic stimulation. It has been suggested that their mRNA expression in peripheral lymphocytes could mirror the changes in their myocardial expression in the failing heart, but this relationship between the myocyte and lymphocyte has not been studied in heart transplantation (HT). The objective of this study was to analyze adrenergic receptor and GRK mRNA expression in myocardium and lymphocytes and their correlation. METHODS Twenty-three HT patients without evidence of acute rejection or echocardiographic dysfunction were assessed. Myocardial biopsy samples and peripheral blood lymphocytes were obtained, and alpha(1)- and beta-adrenoceptor subtype and GRK subtype mRNA was analyzed using reverse transcript-polymerase chain reaction (RT-PCR). RESULTS Mean age was 45 +/- 15 years, with a median of time since HT of 205 (351) days. In biopsies, the beta(1)/beta(2)-adrenoceptor ratio was 57%/42%, and GRK5 was the most commonly expressed, followed by GRK2. In lymphocytes, the beta(1)/beta(2) ratio was 3%/96%, whereas GRK2 mRNA expression was greater than that of other subtypes. There was no correlation between myocardial and lymphocyte parameters. There were no correlations with clinical variables, but lymphocyte beta(2) and GRK2 were increased with time since HT. CONCLUSIONS In the transplanted heart, there is no correlation between mRNA expression of adrenoceptors and GRKs in myocardium and peripheral lymphocytes. With time since transplant, mRNA expression of lymphocyte but not myocardial beta(2)-adrenoceptor and GRK2 increases. Therefore, this dissociation between myocardial and lymphocyte mRNA expression limits the potential use of peripheral blood samples for diagnosis of graft dysfunction.
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Affiliation(s)
- Jaime Agüero
- Heart Failure and Transplant Unit, Department of Cardiology, La Fe University Hospital, Plaza Mestre Vicente Ballester 2-13, Valencia, Spain.
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Granulocyte chemotaxis and disease expression are differentially regulated by GRK subtype in an acute inflammatory arthritis model (K/BxN). Clin Immunol 2008; 129:115-22. [PMID: 18662895 DOI: 10.1016/j.clim.2008.06.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Revised: 05/24/2008] [Accepted: 06/09/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVE Chemokine receptors are G-protein coupled receptors (GPCRs) phosphorylated by G-protein receptor kinases (GRKs) after ligand-mediated activation. We hypothesized that GRK subtypes differentially regulate granulocyte chemotaxis and clinical disease expression in the K/BxN model. METHODS Clinical, histologic, and cytokine responses in GRK6-/-, GRK5-/-, GRK2+/-, and wildtype mice were evaluated using K/BxN serum transfer. Granulocyte chemotaxis was analyzed by transendothelial migration assays. RESULTS Both GRK6-/- and GRK2+/- mice had increased arthritis disease severity (p<0.001); whereas GRK5-/- was not different from controls. Acute weight loss was enhanced in GRK6-/- and GRK2+/- mice (p<0.001, days 3-10). However, GRK6-/- mice uniquely had more weight loss (>10%), elevated serum IL-6, and enhanced migration toward LTB4 and C5a in vitro. CONCLUSIONS GRK6 and -2, but not GRK5, are involved in the pathogenesis of acute arthritis in the K/BxN model. In particular, GRK6 may dampen inflammatory responses by regulating granulocyte trafficking toward chemoattractants.
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Balabanian K, Levoye A, Klemm L, Lagane B, Hermine O, Harriague J, Baleux F, Arenzana-Seisdedos F, Bachelerie F. Leukocyte analysis from WHIM syndrome patients reveals a pivotal role for GRK3 in CXCR4 signaling. J Clin Invest 2008; 118:1074-84. [PMID: 18274673 DOI: 10.1172/jci33187] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Accepted: 12/19/2007] [Indexed: 01/17/2023] Open
Abstract
Leukocytes from individuals with warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome, a rare immunodeficiency, and bearing a wild-type CXCR4 ORF (WHIM(WT)) display impaired CXCR4 internalization and desensitization upon exposure to CXCL12. The resulting enhanced CXCR4-dependent responses, including chemotaxis, probably impair leukocyte trafficking and account for the immunohematologic clinical manifestations of WHIM syndrome. We provided here evidence that GPCR kinase-3 (GRK3) specifically regulates CXCL12-promoted internalization and desensitization of CXCR4. GRK3-silenced control cells displayed altered CXCR4 attenuation and enhanced chemotaxis, as did WHIM(WT) cells. These findings identified GRK3 as a negative regulator of CXCL12-induced chemotaxis and as a candidate responsible for CXCR4 dysfunction in WHIM(WT) leukocytes. Consistent with this, we showed that GRK3 overexpression in both leukocytes and skin fibroblasts from 2 unrelated WHIM(WT) patients restored CXCL12-induced internalization and desensitization of CXCR4 and normalized chemotaxis. Moreover, we found in cells derived from one patient a profound and selective decrease in GRK3 products that probably resulted from defective mRNA synthesis. Taken together, these results have revealed a pivotal role for GRK3 in regulating CXCR4 attenuation and have provided a mechanistic link between the GRK3 pathway and the CXCR4-related WHIM(WT) disorder.
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Differences in motilin receptor desensitization after stimulation with motilin or motilides are due to alternative receptor trafficking. Biochem Pharmacol 2007; 75:1115-28. [PMID: 18096134 DOI: 10.1016/j.bcp.2007.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Revised: 11/09/2007] [Accepted: 11/09/2007] [Indexed: 12/31/2022]
Abstract
BACKGROUNDS & AIMS The motilin receptor (MTLR) is an important therapeutic target for treatment of hypomotility disorders. The negative outcome in clinical trials with the motilin agonist, ABT-229, indicated that desensitization may limit the therapeutic usefulness of motilides. We therefore compared the mechanisms involved in the intracellular trafficking of the MTLR after stimulation with motilin, erythromycin-A (EM-A) or ABT-229. METHODS Desensitization was studied by measuring changes in Ca2+ rises and by receptor binding studies in CHO cells co-expressing the Ca2+ indicator apoaequorin and the MTLR, C-terminally tagged with EGFP. Receptor phosphorylation was studied by immunoprecipitation. MTLR-EGFP trafficking to organelles and translocation of beta-arrestins were visualized by fluorescence microscopy. RESULTS Agonist-induced desensitization of the MTLR was due to receptor internalization with potencies (p-int50) in the order of: ABT-229 (8.3)>motilin (7.86)>EM-A (4.77) but with no differences in the internalization kinetics (t(1/2): approximately 25 min). The percentage cell surface receptor loss was more profound after exposure to ABT-229 (88+/-1%) than to motilin (63+/-10%) or EM-A (34+/-2%). For motilin and EM-A MTLR phosphorylation probably occurs via G protein-coupled receptor kinases while for ABT-229 phosphorylation was also protein kinase C dependent. All agonists translocated cytosolic beta-arrestin-2 with greater affinity to the plasma membrane than beta-arrestin-1. After internalization the MTLR co-localized with transferrin but not with cathepsin D. After stimulation with motilin and EM-A the t(1/2) for MTLR resensitization was 3h and 1h, respectively but amounted 26h for ABT-229. CONCLUSION Our results suggest that the resensitization kinetics determine the desensitization properties of the motilin agonists.
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DeFord-Watts LM, Young JA, Pitcher LA, van Oers NSC. The membrane-proximal portion of CD3 epsilon associates with the serine/threonine kinase GRK2. J Biol Chem 2007; 282:16126-34. [PMID: 17420248 DOI: 10.1074/jbc.m609418200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The activation of protein kinases is one of the primary mechanisms whereby T cell receptors (TCR) propagate intracellular signals. To date, the majority of kinases known to be involved in the early stages of TCR signaling are protein-tyrosine kinases such as Lck, Fyn, and ZAP-70. Here we report a constitutive association between the TCR and a serine/threonine kinase, which was mediated through the membrane-proximal portion of CD3 epsilon. Mass spectrometry analysis of CD3 epsilon-associated proteins identified G protein-coupled receptor kinase 2 (GRK2) as a candidate Ser/Thr kinase. Transient transfection assays and Western blot analysis verified the ability of GRK2 to interact with the cytoplasmic domain of CD3 epsilon within a cell. These findings are consistent with recent reports demonstrating the ability of certain G protein-coupled receptors (GPCR) and G proteins to physically associate with the alpha/beta TCR. Because GRK2 is primarily involved in arresting GPCR signals, its interaction with CD3 epsilon may provide a novel means whereby the TCR can negatively regulate signals generated through GPCRs.
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Affiliation(s)
- Laura M DeFord-Watts
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9093, USA
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Abstract
Heterotrimeric G protein-coupled receptors (GPCRs) are found on the surface of all cells of multicellular organisms and are major mediators of intercellular communication. More than 800 distinct GPCRs are present in the human genome, and individual receptor subtypes respond to hormones, neurotransmitters, chemokines, odorants, or tastants. GPCRs represent the most widely targeted pharmacological protein class. Because drugs that target GPCRs often engage receptor regulatory mechanisms that limit drug effectiveness, particularly in chronic treatment, there is great interest in understanding how GPCRs are regulated, as a basis for designing therapeutic drugs that evade this regulation. The major GPCR regulatory pathway involves phosphorylation of activated receptors by G protein-coupled receptor kinases (GRKs), followed by binding of arrestin proteins, which prevent receptors from activating downstream heterotrimeric G protein pathways while allowing activation of arrestin-dependent signaling pathways. Although the general mechanisms of GRK-arrestin regulation have been well explored in model cell systems and with purified proteins, much less is known about the role of GRK-arrestin regulation of receptors in physiological and pathophysiological settings. This review focuses on the physiological functions and potential pathophysiological roles of GRKs and arrestins in human disorders as well as on recent studies using knockout and transgenic mice to explore the role of GRK-arrestin regulation of GPCRs in vivo.
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Affiliation(s)
- Richard T Premont
- Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
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Wu H, Wei W, Song L, Zhang L, Chen Y, Hu X. Paeoniflorin induced immune tolerance of mesenteric lymph node lymphocytes via enhancing beta 2-adrenergic receptor desensitization in rats with adjuvant arthritis. Int Immunopharmacol 2007; 7:662-73. [PMID: 17386414 DOI: 10.1016/j.intimp.2007.01.019] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Revised: 01/21/2007] [Accepted: 01/22/2007] [Indexed: 12/28/2022]
Abstract
Paeoniflorin (Pae), a monoterpene glucoside, is one of the main bioactive components of total glucosides of paeony (TGP) extracted from the root of Paeonia lactiflora. TGP has anti-inflammatory and immunoregulatory effects. In this study, we investigated the effects of Pae on inflammatory and immune responses to the mesenteric lymph node (MLN) lymphocytes and the mechanisms by which Pae regulates beta 2-adrenergic receptor (beta 2-AR) signal transduction in adjuvant arthritis (AA) rats. The onset of secondary arthritis in rats appeared around day 14 after injection of Freund's complete adjuvant (FCA). Remarkable secondary inflammatory response and lymphocytes proliferation were observed in AA rats, along with the decrease of anti-inflammatory cytokines interleukin (IL)-4 and transforming growth factor-beta 1 (TGF-beta 1) of MLN lymphocytes, and the increase of pro-inflammatory cytokine IL-2. The administration of Pae (50, 100 mg kg(-1), days 17-24) significantly diminished the secondary hind paw swelling and arthritis scores, reversed the changes of cytokines as discussed above, and further decreased the lowered proliferation of MLN lymphocytes in AA rats. In vitro, Pae restored the previously increased level of cAMP of MLN lymphocytes at the concentrations of 12.5, 62.5 and 312.5 mg l(-1). Meanwhile, Pae increased protein expressions of beta 2-AR and GRK2, and decreased that of beta-arrestin 1, 2 of MLN lymphocytes in AA rats. These results suggested that Pae might induce the Th1 cells immune tolerance, which then shift to Th2, Th3 cells mediated activities to take effect the anti-inflammatory and immunoregulatory effects. The mechanisms of Pae on beta 2-AR desensitization and beta 2-AR-AC-cAMP transmembrane signal transduction of MLN lymphocytes play crucial roles in pathogenesis of this disease.
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Affiliation(s)
- Hong Wu
- Institute of Clinical Pharmacology, Anhui Medical University, Key Laboratory of Antiinflammatory-immunopharmacology in Anhui Province, Key Laboratory of Research & Development of Chinese Medicine in Anhui Province, Hefei 230032, Anhui Province, China
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Salim S, Standifer KM, Eikenburg DC. Extracellular signal-regulated kinase 1/2-mediated transcriptional regulation of G-protein-coupled receptor kinase 3 expression in neuronal cells. J Pharmacol Exp Ther 2007; 321:51-9. [PMID: 17255468 DOI: 10.1124/jpet.106.116921] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Relatively small changes in G-protein-coupled receptor kinase (GRK) 3 expression (approximately 2-fold) profoundly affect alpha2-adrenergic receptor (AR) function and preferentially regulate neuronal alpha2A- and alpha2B-AR signaling. In the present study, we provide evidence that epinephrine (EPI)-induced up-regulation of GRK3 protein expression in two neuronal cell lines, BE(2)-C cells (endogenously express alpha2A- and beta2AR) and BN17 cells [endogenously express alpha2B (NG108) and transfected to express beta2-AR] is due in part to increased GRK3 gene expression. In both cell lines, the increase in GRK3 transcription occurred via an extracellular signal-regulated kinase (ERK) 1/2-dependent mechanism because the increase in GRK3 mRNA is eliminated in the presence of the mitogen-activated protein kinase/ERK kinase 1/2 inhibitor, U0126 [1,4-diamino-2,3-dicyano-1,4-bis (2-amino phenylthiobutadiene)]. EPI-induced GRK3 mRNA up-regulation also is prevented in the presence of propranolol or phentolamine. Moreover, GRK3 mRNA did not increase in response to EPI treatment in NG108 cells (endogenously express alpha2B-AR with no beta2-AR). Both these results suggest that simultaneous activation of alpha2- and beta2-AR by EPI is required for the ERK1/2-dependent increase in GRK3 mRNA. The EPI-induced increase in GRK3 mRNA was unaffected in the presence of the protein kinase C inhibitor, chelerythrine chloride. Finally, EPI treatment resulted in increased nuclear translocation and accumulation of the transcription factors, Sp-1 and Ap-2, in BE(2)-C cells. Taken together, our results demonstrate the involvement of the ERK1/2 pathway in selective up-regulation of GRK3 mRNA expression, possibly via activation of Sp-1 and Ap-2 transcription factors in neuronal cells.
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Affiliation(s)
- Samina Salim
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204-5037, USA
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Hansen JL, Theilade J, Aplin M, Sheikh SP. Role of G-protein-coupled receptor kinase 2 in the heart--do regulatory mechanisms open novel therapeutic perspectives? Trends Cardiovasc Med 2006; 16:169-77. [PMID: 16781951 DOI: 10.1016/j.tcm.2006.03.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 03/03/2006] [Accepted: 03/09/2006] [Indexed: 01/08/2023]
Abstract
G-protein-coupled receptor kinase (GRK) 2 regulates a plethora of cellular processes, including cardiac expression and function of key seven-transmembrane receptors (7TM receptors) such as the beta-adrenergic and angiotensin receptors (Penela P, Murga C, Ribas C, et al.: 2006. Mechanisms of regulation of G-protein-coupled receptor kinases [GRKs] and cardiovascular disease. Cardiovasc Res 69:46-56, Rockman HA, Koch WJ, Lefkowitz RJ: 2002. Seven-transmembrane-spanning receptors and heart function. Nature 415:206-212). Interestingly, these two G-protein-coupled receptor systems are targeted by modern heart failure treatment including beta-adrenergic blockers, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers. Although GRK2 is ubiquitously expressed, its particular importance in the heart has been demonstrated by interesting phenotypes of genetically altered mice that suggest GRK2 inhibition can ameliorate heart failure. In essence, this work suggests GRK2 could be an endogenous receptor blocker targeting both the beta-adrenergic and angiotensin receptors in the heart. This notion immediately suggests it is important to understand the molecular mechanisms that regulate GRK2 activity in the heart. In this review, we provide a detailed presentation of the tight regulation of GRK2 expression levels and protein activity, and we discuss the cardiovascular GRK2 functions and possible therapeutic perspectives.
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Affiliation(s)
- Jakob Lerche Hansen
- Laboratory of Molecular and Cellular Cardiology, H:S Rigshospitalet 9312, Department of Medicine B, University of Copenhagen, Juliane Mariesvej 20, DK-2100 Copenhagen, Denmark
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Premont RT. Once and future signaling: G protein-coupled receptor kinase control of neuronal sensitivity. Neuromolecular Med 2005; 7:129-47. [PMID: 16052042 DOI: 10.1385/nmm:7:1-2:129] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2005] [Accepted: 03/02/2005] [Indexed: 12/22/2022]
Abstract
G protein-coupled receptors (GPCRs) are the most numerous class of cell surface receptor, and substances acting through GPCRs mediate many critical signaling events and physiological processes. GPCR sensitivity and signaling is dynamic, responding rapidly to adjust to changes in the ambient level of stimulation of target cells. One important mediator of such receptor sensitivity is the family of GPCR kinases (GRKs). Like heterotrimeric G proteins, GRKs recognize agonist-bound, activated receptors, and this recognition promotes catalytic activation of GRKs, resulting in the preferential phosphorylation of activated receptors. GRK-phosphorylated receptors are then targeted by arrestin proteins, which bind to phosphorylated receptors. Arrestin-bound receptors are uncoupled from heterotrimeric G proteins, resulting in decreased sensitivity to further receptor stimulation (desensitization). Arrestin-bound receptors are also accelerated into internalization pathways and linked to distinct arrestin-mediated signaling pathways. GRKs thus serve as gatekeepers for receptors, terminating some signaling pathways and initiating others. One major outstanding question concerning GRKs understanding the mechanisms by which any particular receptor subtype (of the 800 or so in the body) is regulated by a specific GRK(s), and the consequences of this specificity. An understanding of this regulatory specificity could allow targeting of GRK function to ameliorate diseases involving GPCR dysregulation.
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Affiliation(s)
- Richard T Premont
- Liver Center, Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
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Boterman M, Smits SRJG, Meurs H, Zaagsma J. Protein kinase C potentiates homologous desensitization of the beta2-adrenoceptor in bovine tracheal smooth muscle. Eur J Pharmacol 2005; 529:151-6. [PMID: 16324695 DOI: 10.1016/j.ejphar.2005.10.064] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 10/27/2005] [Accepted: 10/28/2005] [Indexed: 10/25/2022]
Abstract
Preincubation (30 min) of bovine tracheal smooth muscle with various concentrations (0.1, 1 and 10 microM) of fenoterol decreased isoprenaline-induced maximal relaxation (E(max)) of methacholine-contracted preparations in a concentration dependent fashion, indicating desensitization of the beta(2)-adrenoceptor. Preincubation with 1 microM of the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA) caused a small but significant decrease in isoprenaline-induced E(max), indicating activated PKC-mediated heterologous beta(2)-adrenoceptor desensitization. To investigate the capacity of activated PKC to regulate homologous desensitization, we incubated the smooth muscle strips with the combination of both 1 microM PMA and 1 microM fenoterol. This combined treatment synergistically decreased the isoprenaline-induced maximal relaxation, as compared to the individual effects of PMA and fenoterol alone, indicating a common pathway for heterologous and homologous desensitization. Moreover, the specific PKC-inhibitor 2-[1-(3-dimethylaminopropyl)-1H-indol-3-yl]-3-(1H-indol-3-yl) maleimide (GF 109203X) markedly increased the potency and E(max) of isoprenaline for all conditions used, including control conditions, and the synergistic effects of PMA and fenoterol were completely prevented. In conclusion, the present study demonstrates that homologous desensitization of the beta(2)-adrenergic receptor can be enhanced by PKC activation. For the first time we have provided evidence that this concept is functionally operative in airway smooth muscle, and it may explain the reduced bronchodilator response to beta(2)-adrenoceptor agonists in patients with asthma during a severe exacerbation.
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Affiliation(s)
- Mark Boterman
- Department of Molecular Pharmacology, University Centre for Pharmacy, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands.
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Leineweber K, Schwiebert C, Büscher R, Michel MC. Is cyclic AMP formation desensitized in patients with end-stage renal failure? ACTA ACUST UNITED AC 2005; 25:25-32. [PMID: 15659151 DOI: 10.1111/j.1474-8673.2004.00329.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1 Cyclic AMP formation has consistently been reported to be desensitized in various tissues including heart of animal models of end-stage renal failure (ESRF). In contrast, reports on desensitization of cAMP formation in ESRF patients remain contradictory. Whether this discrepancy results from a difference between human ESRF and its animal models or from the use of circulating blood cells in the human and various solid tissues in the animal studies, remains unclear. Therefore, we performed three studies with heart and platelets of ESRF patients undergoing haemodialysis or continuous ambulatory peritoneal dialysis and age- and gender-matched controls with normal renal function (n = 11-13 each). 2 In platelets from haemodialysis patients adenylyl cyclase activity in response to receptor-dependent and -independent agonists was reduced by approximately 30%, and this could be explained by an alteration at the level of adenylyl cyclase itself. However, no such desensitization was seen in platelets from peritoneal dialysis patients. 3 In hearts from ESRF patients undergoing haemodialysis, beta-adrenoceptor density and subtype distribution, cAMP formation in response to the beta-adrenoceptor agonist isoprenaline or various receptor-independent stimuli, were very similar to those in control patients but activity of G-protein-coupled receptor kinase was increased by approximately 20%. 4 We conclude that conflicting reports on the desensitization of cAMP formation between ESRF patients and ESRF animal models are not explained by the use of solid tissues in animal studies vs. circulating blood cells in patient studies. Rather desensitization of cAMP formation seems to be a less consistent feature of human ESRF than of its animal models.
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Affiliation(s)
- K Leineweber
- Department of Pathophysiology, University of Essen, Essen, Germany
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Jiménez-Sainz MC, Murga C, Kavelaars A, Jurado-Pueyo M, Krakstad BF, Heijnen CJ, Mayor F, Aragay AM. G protein-coupled receptor kinase 2 negatively regulates chemokine signaling at a level downstream from G protein subunits. Mol Biol Cell 2005; 17:25-31. [PMID: 16221891 PMCID: PMC1345643 DOI: 10.1091/mbc.e05-05-0399] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The G protein-coupled receptor kinase 2 (GRK2) phosphorylates and desensitizes ligand-activated G protein-coupled-receptors. Here, evidence is shown for a novel role of GRK2 in regulating chemokine-mediated signals. The presence of increased levels of GRK2 in human embryonic kidney (HEK) 293 cells produced a significant reduction of the extracellular signal-regulated kinase (ERK) response to CCL2. This effect is independent of its role in receptor phosphorylation because the kinase-deficient mutant GRK2K220R was able to reduce this response, and ERK activation by CCR2BIX, a phosphorylation-defective receptor mutant, was also inhibited by GRK2. Constructs containing the Galpha(q)-binding RGS-like RH domain of GRK2 or its Gbetagamma-binding domain could not reproduce the inhibition, thus revealing that GRK2 acts downstream of G proteins. Interestingly, chemokine-driven mitogen-activated protein kinase kinase (MEK) stimulation is not affected in cells overexpressing GRK2 or GRK2K220R or in splenocytes from heterozygous GRK2 mice, where reduced kinase levels correlate with enhanced ERK activation by chemokines. We find GRK2 and MEK in the same multimolecular complex, thus suggesting a mechanism for GRK2 regulation of ERK activity that involves a direct or coordinate interaction with MEK. These results suggest an important role for GRK2 in the control of chemokine induction of ERK activation at the level of the MEK-ERK interface.
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Affiliation(s)
- M Carmen Jiménez-Sainz
- Departamento de Biología Molecular and Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049 Madrid, Spain
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Bhatt R, Bhatt S, Hameed M, Rameshwar P, Siegel A. Amygdaloid kindled seizures can induce functional and pathological changes in thymus of rat: role of the sympathetic nervous system. Neurobiol Dis 2005; 21:127-37. [PMID: 16084731 DOI: 10.1016/j.nbd.2005.06.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2005] [Revised: 06/03/2005] [Accepted: 06/15/2005] [Indexed: 12/15/2022] Open
Abstract
The present study sought to determine the effects of long-term kindled seizures of the basal amygdala upon immune function in rat, utilizing the thymus, as a principal target for study. Histopathology from kindled Sprague-Dawley rats revealed the presence of epithelial cell thymoma in 70% of these rats. The results revealed an increased rate of apoptosis and proliferation in thymic epithelial cells. Analysis of thymocytes indicated a decrease in the ratio of CD4 to CD8 positive T cells and reduced proliferative response to T-cell mitogens. To determine whether these effects were mediated through the sympathetic nervous system, animals were treated with guanethidine, which blocked the development of epithelial cell thymomas, while mifepristone treatment, employed to determine the possible role of the hypothalamic-pituitary axis, was ineffective in attenuating thymoma development. Thus, the present study demonstrated that functional and pathological changes in the thymus during kindled seizures are mediated through the sympathetic nervous system.
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Affiliation(s)
- Rekha Bhatt
- Department of Neurology and Neurosciences, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA
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33
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Vroon A, Kavelaars A, Limmroth V, Lombardi MS, Goebel MU, Van Dam AM, Caron MG, Schedlowski M, Heijnen CJ. G protein-coupled receptor kinase 2 in multiple sclerosis and experimental autoimmune encephalomyelitis. THE JOURNAL OF IMMUNOLOGY 2005; 174:4400-6. [PMID: 15778405 DOI: 10.4049/jimmunol.174.7.4400] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Many modulators of inflammation, including chemokines, neuropeptides, and neurotransmitters signal via G protein-coupled receptors (GPCR). GPCR kinases (GRK) can phosphorylate agonist-activated GPCR thereby promoting receptor desensitization. Here we describe that in leukocytes from patients with active relapsing-remitting multiple sclerosis (MS) or with secondary progressive MS, GRK2 levels are significantly reduced. Unexpectedly, cells from patients during remission express even lower levels of GRK2. The level of GRK2 in leukocytes of patients after stroke, a neurological disorder with paralysis but without an autoimmune component, was similar to GRK2 levels in cells from healthy individuals. In addition, we demonstrate that the course of recombinant myelin oligodendrocyte glycoprotein (1-125)-induced experimental autoimmune encephalomyelitis (EAE), an animal model for MS, is markedly different in GRK2(+/-) mice that express 50% of the GRK2 protein in comparison with wild-type mice. Onset of EAE was significantly advanced by 5 days in GRK2(+/-) mice. The earlier onset of EAE was associated with increased early infiltration of the CNS by T cells and macrophages. Although disease scores in the first phase of EAE were similar in both groups, GRK2(+/-) animals did not develop relapses, whereas wild-type animals did. The absence of relapses in GRK2(+/-) mice was associated with a marked reduction in inflammatory infiltrates in the CNS. Recombinant myelin oligodendrocyte glycoprotein-induced T cell proliferation and cytokine production were normal in GRK2(+/-) animals. We conclude that down-regulation of GRK2 expression may have important consequences for the onset and progression of MS.
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Affiliation(s)
- Anne Vroon
- Laboratory for Psychoneuroimmunology, University Medical Center Utrecht, Utrecht, The Netherlands
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34
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Klecha AJ, Barreiro Arcos ML, Genaro AM, Gorelik G, Silberman DM, Caro R, Cremaschi GA. Different mitogen-mediated Beta-adrenergic receptor modulation in murine T lymphocytes depending on the thyroid status. Neuroimmunomodulation 2005; 12:92-9. [PMID: 15785111 DOI: 10.1159/000083581] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2003] [Accepted: 05/25/2004] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE The aim of this work was to analyze beta-adrenergic receptor (betaAR) regulation of T-lymphocyte proliferation in mice according to different thyroid hormone statuses. METHODS T cells from eu-, hypo- (by propylthiouracil treatment) and hyperthyroid (by thyroxine, T4 administration) mice were purified and specific radioligand binding assays were performed. The effects of the beta-agonist isoproterenol (ISO) on intracellular levels of cyclic AMP (cAMP) were determined. Mitogen-induced T-cell proliferation was measured by [(3)H]-thymidine incorporation. Finally, protein kinase C (PKC) activity in cytosol and membrane fractions were determined using radiolabelled enzymatic substrates. RESULTS Adecrease or a non-significant increase in betaAR number was found on T lymphocytes from hypo- and hyperthyroid mice compared to euthyroid controls. ISO stimulation of cAMP levels was lower in hypothyroid and higher in hyperthyroid T lymphocytes compared to controls. T-selective mitogen-induced proliferation was increased in T4-treated animals, but decreased in hypothyroid mice. During the peak of proliferation, downregulation of betaAR was observed in all animals. However, a higher or a lower decrease was observed in hyper- and hypothyroid T cells, respectively. In parallel, a higher translocation of PKC activity was observed in hyperthyroid cells, and a lower one was found in hypothyroid lymphocytes with respect to controls. CONCLUSIONS These results indicate that intracellular signals triggered by mitogen activation, namely PKC, would be related to differential betaAR downregulation in T lymphocytes depending on the thyroid hormone status, contributing to the distinct proliferative responses found in hypo- or hyperthyroidism compared to the euthyroid state.
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Affiliation(s)
- Alicia Juana Klecha
- Laboratorio de Radioisótopos, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
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35
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Giorelli M, Livrea P, Trojano M. Post-receptorial mechanisms underlie functional disregulation of beta2-adrenergic receptors in lymphocytes from Multiple Sclerosis patients. J Neuroimmunol 2004; 155:143-9. [PMID: 15342205 DOI: 10.1016/j.jneuroim.2004.05.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2003] [Revised: 05/24/2004] [Accepted: 05/24/2004] [Indexed: 01/17/2023]
Abstract
Increased density of beta2-adrenergic receptors has been demonstrated on peripheral blood mononuclear cells (PBMCs) from Multiple Sclerosis (MS) patients. In this study we found that isoproterenol reduces T-cell proliferation and IFNgamma secretion in PBMCs cultures from healthy controls and IFNbeta-treated but not untreated MS patients. Reduced expression levels of G protein coupled receptor kinase (GRK)2/3 (p < 0.05) and increased isoproterenol-induced cAMP accumulation (p < 0.0001) were found in PBMCs from all MS patients. Dibutyryl cAMP reduced the proliferation of PBMCs from all subgroups but in a slighter manner in untreated MS patients. We conclude that signalling through beta2-adrenergic receptors is chronically up-regulated but functionally uncoupled to immunoregulatory functions of lymphocytes from MS patients. Disregulation downstream the cAMP-associated signalling may underlie such a phenomenon.
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Affiliation(s)
- Maurizio Giorelli
- Department of Neurologic and Psychiatric Sciences, University of Bari, I-70124 Bari, Italy.
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36
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Penela P, Ribas C, Mayor F. Mechanisms of regulation of the expression and function of G protein-coupled receptor kinases. Cell Signal 2004; 15:973-81. [PMID: 14499340 DOI: 10.1016/s0898-6568(03)00099-8] [Citation(s) in RCA: 204] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
G protein-coupled receptor kinases (GRKs) are key modulators of G protein-coupled receptor signalling. Increasing evidence points to the occurrence of complex mechanisms able to modulate the subcellular localization, activity and expression levels of GRKs, revealing new functional interactions of these kinases with different cellular proteins and transduction cascades. GRK activity and subcellular targeting is tightly regulated by interaction with receptor domains, G protein subunits, lipids, anchoring proteins, caveolin and calcium-sensing proteins. In addition, GRK phosphorylation by several other kinases has recently been shown to modulate its functionality, thus putting forward new feedback mechanisms connecting different signalling pathways to G protein-coupled receptors (GPCR) regulation. On the other hand, the mechanisms governing GRK expression at both transcriptional and protein stability levels are just beginning to be unveiled. Namely, GRK2 has been shown to be rapidly degraded by the proteasome pathway in a process dependent on beta-arrestin and c-Src function, and also to be proteolyzed by m-calpain. A better knowledge of GRK regulatory mechanisms would contribute to greater understanding of GRK physiological function and also its reported alterations in different pathological situations, such as congestive heart failure, hypertension or inflammation.
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Affiliation(s)
- Petronila Penela
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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37
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Vroon A, Heijnen CJ, Lombardi MS, Cobelens PM, Mayor F, Caron MG, Kavelaars A. Reduced GRK2 level in T cells potentiates chemotaxis and signaling in response to CCL4. J Leukoc Biol 2004; 75:901-9. [PMID: 14761932 DOI: 10.1189/jlb.0403136] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Chemokine receptors belong to the family of G-protein-coupled receptors (GPCR). Phosphorylation of GPCR by GPCR kinases (GRKs) is considered to play an important role in desensitization of these receptors. We have recently shown in patients with rheumatoid arthritis that the level of GRK2 in lymphocytes is reduced by approximately 50%. However, the physiological relevance of reduced GRK2 levels in lymphocytes is not known. Here, we investigated whether reduced GRK2 expression changes the chemotactic response of T cells to the chemokines CCL3, CCL4, and CCL5. Activated T cells from GRK2+/- mice, which have a 50% reduction in GRK2 protein levels, showed a significant 40% increase in chemotaxis toward the CCR5 ligand CCL4. In addition, chemotaxis toward the CCR1 and CCR5 ligands CCL3 and CCL5 was also increased. Binding of CCL4 to activated T cells from GRK2+/- and wild-type (WT) mice was similar, but agonist-induced CCR5 phosphorylation was attenuated in GRK2+/- cells. Moreover, the calcium response and phosphorylation of protein kinase B and extracellular-regulated kinase in response to CCL4 were significantly increased in GRK2+/- T cells, showing that signaling is increased when the level of GRK2 is reduced. GRK2+/- and WT cells do become refractory to restimulation with CCL4. In conclusion, a 50% decrease in T cell GRK2 expression results in increased responsiveness to CCL3, CCL4, and CCL5, suggesting that the 50% reduction in lymphocyte GRK2 level as observed during inflammation can have functional consequences for the response of these cells to chemokines.
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Affiliation(s)
- Anne Vroon
- Laboratory for Psychoneuroimmunology, University Medical Center Utrecht, The Netherlands
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38
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Moynihan J, Kruszewska B, Madden K, Callahan T. Sympathetic nervous system regulation of immunity. J Neuroimmunol 2004; 147:87-90. [PMID: 14741434 DOI: 10.1016/j.jneuroim.2003.10.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Jan Moynihan
- The Center for Psychoneuroimmunology Research, University of Rochester Medical Center, 300 Crittenden Boulevard, Rochester, NY 14642, USA.
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39
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Leineweber K, Klapproth S, Beilfuss A, Silber RE, Heusch G, Philipp T, Brodde OE. Unchanged G-protein-coupled receptor kinase activity in the aging human heart. J Am Coll Cardiol 2003; 42:1487-92. [PMID: 14563597 DOI: 10.1016/s0735-1097(03)01063-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES We sought to find out whether G-protein-coupled receptor kinase (GRK) activity is also increased in the aging human heart. BACKGROUND In the aging and failing human heart, cardiac beta-adrenoceptors (beta-AR) are desensitized. In heart failure (HF), an increase in cardiac GRK activity considerably contributes to this beta-AR desensitization. METHODS We assessed GRK activity (by in vitro rhodopsin phosphorylation) in the right atria (RA) from 16 children (mean age 9 +/- 2 years) and 17 elderly patients (mean age 67 +/- 2 years) without apparent HF and in the RA from four patients with end-stage HF.Cytosolic and membranous GRK activities in the RA from children were not significantly different from those in elderly patients; in contrast, cytosolic and membranous GRK activities in the RA from patients with end-stage HF were significantly increased. CONCLUSIONS In contrast to the failing human heart, in the aging human heart, GRK activity is not increased. Thus, GRK activity appears to not play an important role in beta-AR desensitization in the aging human heart.
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Affiliation(s)
- Kirsten Leineweber
- Departments of Pathophysiology and Nephrology, University of Essen School of Medicine, Essen, Germany
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40
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Leineweber K, Seyfarth T, Abraham G, Gerbershagen HP, Heinroth-Hoffmann I, Pönicke K, Brodde OE. Cardiac beta-adrenoceptor changes in monocrotaline-treated rats: differences between membrane preparations from whole ventricles and isolated ventricular cardiomyocytes. J Cardiovasc Pharmacol 2003; 41:333-42. [PMID: 12605011 DOI: 10.1097/00005344-200303000-00001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In monocrotaline (MCT)-treated rats the beta-adrenoceptor-G-protein-adenylyl cyclase system-determined in crude membrane preparations from whole ventricular tissue-was desensitized not only in right (RV) but also in left ventricles (LV). This study aimed to assess the specific contribution of cardiomyocytes to these beta-adrenoceptor changes. Six-week-old male Wistar rats were treated with 60 mg/kg body weight MCT intraperitoneally; within 4-6 weeks, rats developed marked RV hypertrophy. Cardiomyocytes were isolated from RVs and LVs. In RV cardiomyocytes of MCT-treated rats, beta-adrenoceptor density was significantly reduced whereas it was unaltered in LV cardiomyocytes. Reduction of RV cardiomyocyte beta-adrenoceptors was due to a selective beta(1)-adrenoceptor reduction. Isoprenaline (100 microM)-induced cAMP increase was significantly reduced in RV but not in LV cardiomyocytes of MCT-treated rats. G protein-coupled receptor kinase activity was increased in RV but not in LV cardiomyocytes. alpha(1)-Adrenoceptor density and noradrenaline-induced increase in inositol phosphate formation were significantly reduced only in RV but not in LV cardiomyocytes from MCT-treated rats. It is concluded that in cardiomyocytes of MCT-treated rats, cardiac beta-adrenoceptors and alpha -adrenoceptors are chamber-specifically desensitized only in the RV. Thus, changes in cardiac beta-adrenoceptors determined in membrane preparations from whole tissue homogenates do not correctly reflect changes occurring in cardiomyocytes.
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Affiliation(s)
- Kirsten Leineweber
- Institute of Pharmacology, Martin-Luther-University of Halle-Wittenberg, Halle, Germany
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41
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Sanders VM, Kohm AP. Sympathetic nervous system interaction with the immune system. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2003; 52:17-41. [PMID: 12498099 DOI: 10.1016/s0074-7742(02)52004-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Virginia M Sanders
- Department of Molecular Virology, Immunology, and Medical Genetics, Ohio State University, Columbus, Ohio 43210, USA
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42
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Affiliation(s)
- Kelley S Madden
- Department of Psychiatry, Center for Psychoneuroimmunology Research, University of Rochester School of Medicine and Dentistry, NY 14642, USA.
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43
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Leineweber K, Brandt K, Wludyka B, Beilfuss A, Pönicke K, Heinroth-Hoffmann I, Brodde OE. Ventricular hypertrophy plus neurohumoral activation is necessary to alter the cardiac beta-adrenoceptor system in experimental heart failure. Circ Res 2002; 91:1056-62. [PMID: 12456492 DOI: 10.1161/01.res.0000045088.59360.b7] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Treatment of rats with monocrotaline (MCT) leads to pulmonary hypertension, right ventricular (RV) hypertrophy, and finally to RV heart failure. This is associated with characteristic changes in right ventricular beta-adrenoceptors (beta-AR), neuronal noradrenaline transporter (NAT) density and activity (uptake1), and G protein-coupled receptor kinase (GRK) activity. This study aimed to find out factors that determine beta-AR, uptake1, and GRK changes. Thus, 6-week-old rats were treated with 50 mg/kg MCT subcutaneous or 0.9% saline. Within 13 to 19 days after MCT application (group A), RV weight (222+/-6 versus 147+/-5 mg) and RV/left ventricular (LV) weight ratio (0.42+/-0.01 versus 0.29+/-0.01) were significantly increased, whereas plasma noradrenaline, RV beta-AR density, RV NAT density and activity, and RV GRK activity were not significantly altered. Twenty-one to twenty-eight days after MCT (group B), however, not only RV weight (316+/-4 versus 148+/-2 mg) and RV/LV weight ratio (0.61+/-0.01 versus 0.3+/-0.01) were markedly increased but also plasma noradrenaline (645+/-63 versus 278+/-18 pg/mL); now, RV beta-AR density (13.4+/-1.3 versus 26.5+/-1.1 fmol/mg protein), RV NAT density (50.9+/-11.3 versus 79.6+/-2.9 fmol/mg protein), and RV NAT activity (65.4+/-7.4 versus 111.8+/-15.9 pmol [3H]-NA/mg tissue slices/15 min) were significantly decreased and RV-membrane GRK activity (100+/-15 versus 67+/-6 [32P]-rhodopsin in cpm) significantly increased. LV parameters of MCT-treated rats were only marginally different from control LV. We conclude that in MCT-treated rats ventricular hypertrophy per se is not sufficient to cause characteristic alterations in the myocardial beta-AR system often seen in heart failure; only if ventricular hypertrophy is associated with neurohumoral activation beta-ARs are downregulated and GRK activity is increased.
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MESH Headings
- Animals
- Binding, Competitive/drug effects
- Binding, Competitive/physiology
- Cell Membrane/chemistry
- Cell Membrane/metabolism
- Disease Models, Animal
- Eye Proteins
- Fluoxetine/analogs & derivatives
- Fluoxetine/pharmacokinetics
- G-Protein-Coupled Receptor Kinase 1
- Heart Failure/chemically induced
- Heart Failure/complications
- Heart Failure/physiopathology
- Hypertension, Pulmonary/chemically induced
- Hypertension, Pulmonary/complications
- Hypertrophy, Right Ventricular/chemically induced
- Hypertrophy, Right Ventricular/complications
- Hypertrophy, Right Ventricular/physiopathology
- Male
- Monocrotaline
- Myocardium/metabolism
- Norepinephrine/blood
- Norepinephrine/pharmacokinetics
- Norepinephrine Plasma Membrane Transport Proteins
- Organ Size/drug effects
- Protein Kinases/metabolism
- Rats
- Rats, Wistar
- Receptors, Adrenergic, beta/metabolism
- Receptors, Neurotransmitter/metabolism
- Rhodopsin/pharmacokinetics
- Symporters/analysis
- Symporters/metabolism
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Affiliation(s)
- Kirsten Leineweber
- Institute of Pharmacology, Martin-Luther-University of Halle-Wittenberg, Halle, Germany
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44
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Dautzenberg FM, Wille S, Braun S, Hauger RL. GRK3 regulation during CRF- and urocortin-induced CRF1 receptor desensitization. Biochem Biophys Res Commun 2002; 298:303-8. [PMID: 12413940 DOI: 10.1016/s0006-291x(02)02463-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The EC(50) values for concentration-dependent stimulation of cAMP accumulation by CRF (1.3nM) and urocortin (1.0nM) were equivalent in human retinoblastoma Y79 cells. The time course and magnitude of CRF- and urocortin-induced CRF(1) receptor desensitization were similar. A significant 3-fold increase in GRK3, but not GRK2, mRNA levels accompanied the emergence of CRF(1) receptor desensitization in Y79 cells exposed to CRF. In preliminary experiments, retinoblastoma GRK3 protein expression became upregulated during a 48-h CRF exposure. Neither GRK3 nor GRK2 expression increased in Y79 cells exposed to urocortin for 10 min to 48 h. We hypothesize that GRK3 upregulation may be a cellular negative feedback process directed at maximizing CRF(1) receptor desensitization by heightening GRK3 phosphorylating capacity during prolonged exposure to high CRF. Regulation of GRK expression associated with urocortin- and CRF-induced CRF(1) receptor desensitization appears to differ, despite a similar level of signaling via the cAMP-protein kinase A pathway.
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Affiliation(s)
- Frank M Dautzenberg
- Pharma Division, Preclinical Research, F-Hoffmann-La Roche AG, CH-4070 Basel, Switzerland.
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45
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Thakker DR, Standifer KM. Induction of G protein-coupled receptor kinases 2 and 3 contributes to the cross-talk between mu and ORL1 receptors following prolonged agonist exposure. Neuropharmacology 2002; 43:979-90. [PMID: 12423667 DOI: 10.1016/s0028-3908(02)00145-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The molecular mechanism(s) underlying cross-tolerance between mu and opioid receptor-like 1 (ORL1) receptor agonists were investigated using two human neuroblastoma cell lines endogenously expressing these receptors and G protein-coupled receptor kinases (GRKs). Prolonged (24 h) activation of the mu receptor desensitized both mu and ORL1 receptor-mediated inhibition of forskolin-stimulated cAMP accumulation and upregulated GRK2 levels in SH-SY5Y and BE(2)-C cells. Prolonged ORL1 activation increased GRK2 levels and desensitized both receptors in SH-SY5Y cells. Upregulation of GRK2 correlated with increases in levels of transcription factors Sp1 or AP-2. PD98059, an upstream inhibitor of extracellular signal-regulated kinases 1 and 2 (ERK1/2), reversed all these events. Pretreatment with orphanin FQ/nociceptin (OFQ/N) also upregulated GRK3 levels in both cell lines, and desensitized both receptors in BE(2)-C cells. Protein kinase C (PKC), but not ERK1/2, inhibition blocked OFQ/N-mediated GRK3 induction and mu and ORL1 receptor desensitization in BE(2)-C cells. Antisense DNA treatment confirmed the involvement of GRK2/3 in mu and ORL1 desensitization. Here, we demonstrate for the first time a role for ERK1/2-mediated GRK2 induction in the development of tolerance to mu agonists, as well as cross-tolerance to OFQ/N. We also demonstrate that chronic OFQ/N-mediated desensitization of ORL1 and mu receptors occurs via cell-specific pathways, involving ERK1/2-dependent GRK2, or PKC-dependent and ERK1/2-independent GRK3 induction.
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MESH Headings
- Analysis of Variance
- Cell Membrane/metabolism
- Cyclic AMP/metabolism
- Cyclic AMP-Dependent Protein Kinases/biosynthesis
- Cyclic AMP-Dependent Protein Kinases/physiology
- Dose-Response Relationship, Drug
- Drug Interactions
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Enzyme Inhibitors/pharmacology
- Flavonoids/pharmacology
- G-Protein-Coupled Receptor Kinase 3
- Humans
- Mitogen-Activated Protein Kinases/physiology
- Morphine/agonists
- Morphine/pharmacology
- Neuroblastoma
- Oligodeoxyribonucleotides, Antisense/pharmacology
- Opioid Peptides/pharmacology
- Protein Serine-Threonine Kinases/biosynthesis
- Protein Serine-Threonine Kinases/physiology
- Receptor Cross-Talk/physiology
- Receptors, Opioid/agonists
- Receptors, Opioid/physiology
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/physiology
- Transcription Factors/drug effects
- Transcription Factors/metabolism
- Tumor Cells, Cultured
- beta-Adrenergic Receptor Kinases
- Nociceptin Receptor
- Nociceptin
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Affiliation(s)
- D R Thakker
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, TX 77204-5037, USA
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46
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Giorelli M, De Blasi A, Defazio G, Avolio C, Iacovelli L, Livrea P, Trojano M. Differential regulation of membrane bound and soluble ICAM 1 in human endothelium and blood mononuclear cells: effects of interferon beta-1a. CELL COMMUNICATION & ADHESION 2002; 9:259-72. [PMID: 12745437 DOI: 10.1080/15419060216305] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The membrane-associated Intercellular Adhesion Molecule 1 (mICAM 1) is fundamental for adhesion of leukocytes to endothelial cells. A soluble form of ICAM 1 (sICAM 1) exists in the human serum, and is seen as marker of disease activity in patients suffering from Multiple Sclerosis (MS). High levels of sICAM 1 have been detected in MS patients benefiting from interferon beta (IFNbeta) treatment, but little is known on the molecular origins of sICAM 1. This study investigated the interrelationship and the mechanisms of production of sICAM 1 and mICAM 1 in human endothelium (Human Umbilical Vein Endothelial Cells, HUVECs) and mononuclear leukocytes (MNL) upon stimulation with IFNbeta-1a and other inducers. We found that the expression of mICAM 1 and the release of sICAM 1 are differentially regulated in both these cytotypes. HUVECs and MNL express specific mRNA for both mICAM 1 and sICAM 1, and modification of the content of each of these transcripts results in regulation of both the ICAM 1 isoforms. We show that IFNbeta-1a is strong regulator of the ICAM 1 RNA splicing machinery. Effect of IFNbeta-1a over expression of the ICAM 1 isoforms might have a relevant immunomoregulatory role in Multiple Sclerosis.
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Affiliation(s)
- Maurizio Giorelli
- Department of Neurologic and Psychiatric Sciences, University of Bari, Bari, Italy.
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47
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Mandyam CD, Thakker DR, Christensen JL, Standifer KM. Orphanin FQ/nociceptin-mediated desensitization of opioid receptor-like 1 receptor and mu opioid receptors involves protein kinase C: a molecular mechanism for heterologous cross-talk. J Pharmacol Exp Ther 2002; 302:502-9. [PMID: 12130708 DOI: 10.1124/jpet.102.033159] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Morphine tolerance in vivo is reduced following blockade of the orphanin FQ/nociceptin (OFQ/N)/opioid receptor-like 1 (ORL1) receptor system, suggesting that OFQ/N contributes to the development of morphine tolerance. We previously reported that a 60-min activation of ORL1 receptors natively expressed in BE(2)-C cells desensitized both mu and ORL1 receptor-mediated inhibition of cAMP. Investigating the mechanism(s) of OFQ/N-mediated mu and ORL1 receptor cross-talk, we found that pretreatment with the protein kinase C inhibitor, chelerythrine chloride (1 microM), blocked OFQ/N-mediated homologous desensitization of ORL1 and heterologous desensitization of mu opioid receptors. Furthermore, depletion of PKC by 12-O-tetradecanoylphorbol-13-acetate exposure (48 h, 1 microM) also prevented OFQ/N-mediated mu and ORL1 desensitization. OFQ/N pretreatment resulted in translocation of PKC-alpha, G protein-coupled receptor kinase 2 (GRK2) and GRK3 from the cytosol to the membrane, and this translocation was also blocked by chelerythrine. Reduction of GRK2 and GRK3 levels by antisense, but not sense DNA treatment blocks ORL1 and mu receptor desensitization. This suggests that PKC-alpha is required for GRK2 and GRK3 translocation to the membrane, where GRK can inactivate ORL1 and mu opioid receptors upon rechallenge with the appropriate agonist. Our results demonstrate for the first time the involvement of conventional PKC isozymes in OFQ/N-induced mu-ORL1 cross-talk, and represent a possible mechanism for OFQ/N-induced anti-opioid actions.
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MESH Headings
- Alkaloids
- Benzophenanthridines
- Cell Membrane/metabolism
- Cyclic AMP/metabolism
- Cyclic AMP-Dependent Protein Kinases/genetics
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacokinetics
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Enzyme Inhibitors/pharmacology
- G-Protein-Coupled Receptor Kinase 3
- Humans
- Neuroblastoma
- Oligodeoxyribonucleotides, Antisense/pharmacology
- Opioid Peptides/pharmacology
- Phenanthridines/pharmacology
- Protein Kinase C/antagonists & inhibitors
- Protein Serine-Threonine Kinases/genetics
- Receptor Cross-Talk/physiology
- Receptors, Opioid/drug effects
- Receptors, Opioid/physiology
- Receptors, Opioid, mu/drug effects
- Receptors, Opioid, mu/physiology
- Tetradecanoylphorbol Acetate/pharmacology
- Tumor Cells, Cultured
- beta-Adrenergic Receptor Kinases
- Nociceptin Receptor
- Nociceptin
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Affiliation(s)
- Chitra D Mandyam
- Department of Pharmacological and Pharmaceutical Sciences, 521 Building Science and Research 2, University of Houston, Houston, TX 77204-5037, USA
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48
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Lombardi MS, Kavelaars A, Penela P, Scholtens EJ, Roccio M, Schmidt RE, Schedlowski M, Mayor F, Heijnen CJ. Oxidative stress decreases G protein-coupled receptor kinase 2 in lymphocytes via a calpain-dependent mechanism. Mol Pharmacol 2002; 62:379-88. [PMID: 12130691 DOI: 10.1124/mol.62.2.379] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
G protein-coupled receptor kinase (GRK) 2 plays a crucial role in regulating the extent of desensitization and resensitization of G protein-coupled receptors (GPCRs). We have shown that the expression level of GRK2 in lymphocytes decreases during inflammatory diseases such as arthritis. Reactive oxygen species play an important role in a variety of inflammatory conditions, including arthritis. We demonstrate herein that oxidative stress, induced by exposure of lymphocytes to H(2)O(2), results in a 50% reduction in GRK2 protein levels and GRK activity with no changes in mRNA expression. Treatment of lymphocytes with the tyrosine kinase inhibitor genistein partially reverses the effect of H(2)O(2) on GRK2 levels, although we did not detect direct tyrosine phosphorylation of GRK2. Inhibition of the nonproteasomal protease calpain by calpeptin can prevent the H(2)O(2)-induced GRK2 decrease. In vitro experiments confirm that GRK2 is partially digested by m-calpain in a calcium-dependent way. Functionally, H(2)O(2)-induced decrease in GRK2 levels is associated with an ~70% decrease in agonist-induced beta(2)-adrenergic receptor sequestration. We describe oxidative stress as a novel mechanism for regulation of the intracellular level of GRK2 during inflammatory processes. Moreover, our data demonstrate that oxidative stress may change the functioning of GPCRs via calpain-dependent regulation of GRK2 levels.
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Affiliation(s)
- Maria Stella Lombardi
- Department of Immunology, Laboratory of Psychoneuroimmunology, University Medical Center, Utrecht, The Netherlands
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49
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Giorelli M, Livrea P, Defazio G, Iacovelli L, Capobianco L, Picascia A, Sallese M, Martino D, Aniello MS, Trojano M, De Blasi A. Interferon beta-1a counteracts effects of activation on the expression of G-protein-coupled receptor kinases 2 and 3, beta-arrestin-1, and regulators of G-protein signalling 2 and 16 in human mononuclear leukocytes. Cell Signal 2002; 14:673-8. [PMID: 12020767 DOI: 10.1016/s0898-6568(02)00011-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Activation regulates the responsiveness of G-protein-coupled receptors (GPCRs) on T cells, and modifications in the activity of GPCRs characterize lymphocytes from some immune disorders such as multiple sclerosis (MS) and rheumatoid arthritis (RA). Some lines of evidence suggest that such an effect is connected with the altered expression of some GPCRs regulatory proteins. Herein we demonstrate that phitoemagglutinin (PHA)-induced activation leads to differential expression of G-protein-coupled receptor kinase (GRK) 2, GRK3, beta-arrestin-1, regulators of G-protein signalling (RGS) 2, and RGS16 and decreases responsiveness of mononuclear leukocytes (MNL) to the beta-adrenergic agonist isoproterenol. Interferon beta-1a (IFN beta-1a), which is known to ameliorate the course of MS, counteracts the activation-induced effects on the expression of these GPCR regulatory proteins in MNL. Furthermore, IFN beta-1a quenches the effects of PHA on the isoproterenol-induced accumulation of cyclic AMP (cAMP). We suggest that regulation of GPCRs responsiveness may be a relevant property of IFN beta-1a in MS.
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Affiliation(s)
- Maurizio Giorelli
- Department of Neurologic and Psychiatric Sciences, University of Bari, I-70124 Bari, Italy.
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50
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Theilade J, Lerche Hansen J, Haunsø S, Sheikh SP. Extracellular signal-regulated kinases control expression of G protein-coupled receptor kinase 2 (GRK2). FEBS Lett 2002; 518:195-9. [PMID: 11997045 DOI: 10.1016/s0014-5793(02)02701-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
G protein-coupled receptor kinase 2 (GRK2) phosphorylates G protein-coupled receptors resulting in uncoupling from G proteins. Receptors modulate GRK2 expression, however the mechanistic basis for this effect is largely unknown. Here we report a novel mechanism by which receptors use the extracellular signal-regulated kinase (ERK) cascade to regulate GRK2 cellular levels. ERK activation by receptor stimulation elevated endogenous GRK2 while antagonist treatment decreased cellular GRK2. Activating ERK by overexpressing constitutive active MEK-1 or Ras elevated GRK2 protein levels while blocking ERK using PD98059 or dominant negative Ras abolished this effect. These data suggest ERK is a critical regulator of GRK2 levels.
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Affiliation(s)
- Juliane Theilade
- Laboratory for Molecular Cardiology and Department of Medicine B, Rigshospitalet 9312, University of Copenhagen, Juliane Mariesvej 20, DK-2100, Copenhagen, Denmark
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