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Inagaki S, Ghirlando R, Vishnivetskiy SA, Homan KT, White JF, Tesmer JJG, Gurevich VV, Grisshammer R. G Protein-Coupled Receptor Kinase 2 (GRK2) and 5 (GRK5) Exhibit Selective Phosphorylation of the Neurotensin Receptor in Vitro. Biochemistry 2015; 54:4320-9. [PMID: 26120872 PMCID: PMC4512254 DOI: 10.1021/acs.biochem.5b00285] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
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G protein-coupled
receptor kinases (GRKs) play an important role
in the desensitization of G protein-mediated signaling of G protein-coupled
receptors (GPCRs). The level of interest in mapping their phosphorylation
sites has increased because recent studies suggest that the differential
pattern of receptor phosphorylation has distinct biological consequences. In vitro phosphorylation experiments using well-controlled
systems are useful for deciphering the complexity of these physiological
reactions and understanding the targeted event. Here, we report on
the phosphorylation of the class A GPCR neurotensin receptor 1 (NTSR1)
by GRKs under defined experimental conditions afforded by nanodisc
technology. Phosphorylation of NTSR1 by GRK2 was agonist-dependent,
whereas phosphorylation by GRK5 occurred in an activation-independent
manner. In addition, the negatively charged lipids in the immediate
vicinity of NTSR1 directly affect phosphorylation by GRKs. Identification
of phosphorylation sites in agonist-activated NTSR1 revealed that
GRK2 and GRK5 target different residues located on the intracellular
receptor elements. GRK2 phosphorylates only the C-terminal Ser residues,
whereas GRK5 phosphorylates Ser and Thr residues located in intracellular
loop 3 and the C-terminus. Interestingly, phosphorylation assays using
a series of NTSR1 mutants show that GRK2 does not require acidic residues
upstream of the phospho-acceptors for site-specific phosphorylation,
in contrast to the β2-adrenergic and μ-opioid
receptors. Differential phosphorylation of GPCRs by GRKs is thought
to encode a particular signaling outcome, and our in vitro study revealed NTSR1 differential phosphorylation by GRK2 and GRK5.
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Affiliation(s)
- Sayaka Inagaki
- †Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, Maryland 20852, United States
| | - Rodolfo Ghirlando
- ‡Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892, United States
| | - Sergey A Vishnivetskiy
- §Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Kristoff T Homan
- ∥Departments of Pharmacology and Biological Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jim F White
- †Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, Maryland 20852, United States
| | - John J G Tesmer
- ∥Departments of Pharmacology and Biological Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Vsevolod V Gurevich
- §Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Reinhard Grisshammer
- †Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, Maryland 20852, United States
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Rinaldi B, Donniacuo M, Sodano L, Gritti G, Martuscelli E, Orlandi A, Rafaniello C, Rossi F, Calzetta L, Capuano A, Matera MG. Effects of chronic treatment with the new ultra-long-acting β2 -adrenoceptor agonist indacaterol alone or in combination with the β1 -adrenoceptor blocker metoprolol on cardiac remodelling. Br J Pharmacol 2015; 172:3627-37. [PMID: 25825265 DOI: 10.1111/bph.13148] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 03/21/2015] [Accepted: 03/26/2015] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND AND PURPOSE The ability of a chronic treatment with indacaterol, a new ultra-long-acting β2 -adrenoceptor agonist, to reverse cardiac remodelling and its effects in combination with metoprolol, a selective β1 -adrenoceptor antagonist, were investigated on myocardial infarction in a rat model of heart failure (HF). EXPERIMENTAL APPROACH We investigated the effects of indacaterol and metoprolol, administered alone or in combination, on myocardial histology, β-adrenoceptor-mediated pathways, markers of remodelling and haemodynamic parameters in a rat model of HF. Five groups of rats were assessed: sham-operated rats; HF rats; HF + indacaterol 0.3 mg·kg(-1) ·day(-1) ; HF + metoprolol 100 mg·kg(-1) ·day(-1) ; HF + metoprolol + indacaterol. All pharmacological treatments continued for 15 weeks. KEY RESULTS Treatment with either indacaterol or metoprolol significantly reduced the infarct size in HF rats. However, the combination of indacaterol and metoprolol reduced the infarct size even further, reduced both BP and heart rate, reversed the decrease in ejection fraction, normalized left ventricular systolic and diastolic internal diameters, normalized the decreased β1 adrenoceptor mRNA expression as well as cardiac cAMP levels and reduced cardiac GPCR kinase 2 expression, compared with the untreated HF group. CONCLUSION AND IMPLICATIONS The results of our study demonstrated an additive interaction between indacaterol and metoprolol in normalizing and reversing cardiac remodelling in our experimental model of HF. The translation of these findings to clinical practice might be of interest, as this combination of drugs could be safer and more effective in patients suffering from HF and COPD.
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Affiliation(s)
- Barbara Rinaldi
- Centre of Excellence for Cardiovascular Diseases, Second University of Naples, Naples, Italy.,Regional Centre for Pharmacovigilance and Pharmacoepidemiology, Department of Experimental Medicine, Section of Pharmacology L. Donatelli, Second University of Naples, Naples, Italy
| | - Maria Donniacuo
- Centre of Excellence for Cardiovascular Diseases, Second University of Naples, Naples, Italy
| | - Loredana Sodano
- Centre of Excellence for Cardiovascular Diseases, Second University of Naples, Naples, Italy
| | - Giulia Gritti
- Centre of Excellence for Cardiovascular Diseases, Second University of Naples, Naples, Italy
| | - Eugenio Martuscelli
- Department of Systems Medicine, University of Rome 'Tor Vergata', Rome, Italy
| | - Augusto Orlandi
- Anatomic Pathology, Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Rome, Italy
| | - Concetta Rafaniello
- Centre of Excellence for Cardiovascular Diseases, Second University of Naples, Naples, Italy.,Regional Centre for Pharmacovigilance and Pharmacoepidemiology, Department of Experimental Medicine, Section of Pharmacology L. Donatelli, Second University of Naples, Naples, Italy
| | - Francesco Rossi
- Centre of Excellence for Cardiovascular Diseases, Second University of Naples, Naples, Italy.,Regional Centre for Pharmacovigilance and Pharmacoepidemiology, Department of Experimental Medicine, Section of Pharmacology L. Donatelli, Second University of Naples, Naples, Italy
| | - Luigino Calzetta
- Department of Systems Medicine, University of Rome 'Tor Vergata', Rome, Italy
| | - Annalisa Capuano
- Centre of Excellence for Cardiovascular Diseases, Second University of Naples, Naples, Italy.,Regional Centre for Pharmacovigilance and Pharmacoepidemiology, Department of Experimental Medicine, Section of Pharmacology L. Donatelli, Second University of Naples, Naples, Italy
| | - Maria Gabriella Matera
- Centre of Excellence for Cardiovascular Diseases, Second University of Naples, Naples, Italy
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3
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Rinaldi B, Capuano A, Gritti G, Donniacuo M, Scotto Di Vettimo A, Sodano L, Rafaniello C, Rossi F, Matera MG. Effects of chronic administration of β-blockers on airway responsiveness in a murine model of heart failure. Pulm Pharmacol Ther 2014; 28:109-13. [PMID: 24769100 DOI: 10.1016/j.pupt.2014.04.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 03/29/2014] [Accepted: 04/11/2014] [Indexed: 12/21/2022]
Abstract
Lung function abnormalities, both at rest and during exercise, are frequently observed in patients with chronic heart failure (HF), also in absence of respiratory disease. It has been documented that, in HF, chronic adrenergic stimulation down-regulates β-adrenoceptors (β-ARs) and modifies airway relaxant responses. This study was designed to investigate in an animal model of HF whether a treatment with a β-AR blocker, metoprolol, could modify the altered airway hyperresponsiveness. In rats, randomly assigned to 3 experimental groups sham-operated rats (SH), rats with HF induced by left anterior descending coronaric occlusion (HF n = 10), and rats treated with metoprolol 100 mg/kg/die (MET = 10), HF was evaluated after 10 weeks and resulted in increases in plasma norepinephrine and epinephrine and left ventricular end diastolic pressure. β2-ARs and G-protein-βAR2-kinase (GRK2) mRNA levels were determined by real time reverse transcriptase PCR. Carbachol-precontracted isolated tracheal rings were used to functionally assess airway smooth muscle relaxation. In pulmonary tissues, β2-AR mRNA level was significantly decreased in HF groups (-48.73 ± 5.18%, P < 0.01); in the same groups the GRK2 mRNA-levels were significantly enhanced (+222.50 ± 6.13%, P < 0.001); in lung deriving from MET groups the levels of mRNA were significantly increased (+339.86 ± 11.26%, P < 0.001), while the GRK2 mRNA-levels unchanged (-59.02 ± 3.97%, P < 0.001), when compared to SH groups. Relaxation of tracheal strips in response to salbutamol was significantly reduced in HF groups; in tracheal rings, deriving from MET groups, the relaxant effects of salbutamol were significantly enhanced (SH, Emax: 34.87 ± 2.98%, pD2: 7.45 ± 0.27; HF, Emax: 34.87 ± 2.98%, pD2: 7.45 ± 0.27; MET, Emax: 85.43 ± 6.80%, pD2: 6.95 ± 0.59, P < 0.001). In HF, the down-regulation of pulmonary β-ARs results in a significant attenuation of airway relaxation. These effects have been reversed by a treatment with metoprolol, suggesting a potential role of β-AR blockers in the treatment of patients suffering from HF and chronic obstructive airway diseases.
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Affiliation(s)
- B Rinaldi
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy; Regional Centre for Pharmacovigilance and Pharmacoepidemiology, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - A Capuano
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy; Regional Centre for Pharmacovigilance and Pharmacoepidemiology, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - G Gritti
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - M Donniacuo
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - A Scotto Di Vettimo
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - L Sodano
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - C Rafaniello
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy; Regional Centre for Pharmacovigilance and Pharmacoepidemiology, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - F Rossi
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy; Regional Centre for Pharmacovigilance and Pharmacoepidemiology, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - M G Matera
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy.
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Abstract
G-protein-coupled receptors (GPCRs) are the primary interaction partners for arrestins. The visual arrestins, arrestin1 and arrestin4, physiologically bind to only very few receptors, i.e., rhodopsin and the color opsins, respectively. In contrast, the ubiquitously expressed nonvisual variants β-arrestin1 and 2 bind to a large number of receptors in a fairly nonspecific manner. This binding requires two triggers, agonist activation and receptor phosphorylation by a G-protein-coupled receptor kinase (GRK). These two triggers are mediated by two different regions of the arrestins, the "phosphorylation sensor" in the core of the protein and a less well-defined "activation sensor." Binding appears to occur mostly in a 1:1 stoichiometry, involving the N-terminal domain of GPCRs, but in addition a second GPCR may loosely bind to the C-terminal domain when active receptors are abundant.Arrestin binding initially uncouples GPCRs from their G-proteins. It stabilizes receptors in an active conformation and also induces a conformational change in the arrestins that involves a rotation of the two domains relative to each other plus changes in the polar core. This conformational change appears to permit the interaction with further downstream proteins. The latter interaction, demonstrated mostly for β-arrestins, triggers receptor internalization as well as a number of nonclassical signaling pathways.Open questions concern the exact stoichiometry of the interaction, possible specificity with regard to the type of agonist and of GRK involved, selective regulation of downstream signaling (=biased signaling), and the options to use these mechanisms as therapeutic targets.
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Affiliation(s)
- Martin J Lohse
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Straße 9, 97078, Würzburg, Germany,
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5
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Schutzer WE, Xue H, Reed J, Oyama T, Beard DR, Anderson S, Mader SL. Age-related β-adrenergic receptor-mediated vasorelaxation is changed by altering G protein receptor kinase 2 expression. Vascul Pharmacol 2011; 55:178-88. [PMID: 21951806 DOI: 10.1016/j.vph.2011.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 08/18/2011] [Accepted: 09/08/2011] [Indexed: 11/26/2022]
Abstract
Beta-adrenergic receptor- (β-AR) mediated vasorelaxation declines with age. This change is likely related to receptor desensitization, rather than down regulation. One kinase responsible for desensitization is G protein receptor kinase 2 (GRK2). We have shown that GRK expression and activity increases with age in Fischer 344 rat aorta. In this study we validated that carotid arteries have similar age-related changes in the β-AR signaling axis as aorta. This finding allowed use of in vivo infection and delivery of two adenovirus vectors to carotid arteries of 2-month-old (2M) and 12-month-old (12M) male Fischer 344 rats. Adeno-GRK2 was used to overexpress GRK2, and adeno-β-ARK-ct was used to inhibit GRK2 function. Following a five-day infection, vessels were collected and ex vivo tissue bath was used to evaluate vasoreactivity. We used KCl contracted segments, and determined that overexpression of GRK2 significantly impaired isoproterenol (ISO)-mediated vasorelaxation in both age groups. Maximum relaxation (MAX) to ISO in vessels from 2M decreased from 44% to 21%. MAX to ISO in vessels from 12M decreased from 12% to 6%. Sensitivity (ED₅₀) in vessels from 2M and 12M was also impaired 57%, and 30% respectively. We also determined that expression of adeno-β-ARK-ct significantly improved ISO-mediated vasorelaxation in both age groups. MAX in vessels from 2M increased from 44% to 58%. MAX in vessels from 12M increased from 15% to 69%. ED₅₀ in vessels from 2M and 12M was also improved 46%, and 50% respectively. These findings further implicate age-related increases in GRK2 expression as an important regulator of the age-related decline in β-AR-mediated vasorelaxation.
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Affiliation(s)
- William E Schutzer
- Portland VA Medical Center, Research Service, 3710 SW US Veterans Hospital Rd., Portland, OR 97239, United States
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6
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Gądek-Michalska A, Bugajski J. Interleukin-1 (IL-1) in stress-induced activation of limbic-hypothalamic-pituitary adrenal axis. Pharmacol Rep 2010; 62:969-82. [DOI: 10.1016/s1734-1140(10)70359-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Revised: 10/26/2010] [Indexed: 01/07/2023]
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Klenk C, Vetter T, Zürn A, Vilardaga JP, Friedman PA, Wang B, Lohse MJ. Formation of a ternary complex among NHERF1, beta-arrestin, and parathyroid hormone receptor. J Biol Chem 2010; 285:30355-62. [PMID: 20656684 DOI: 10.1074/jbc.m110.114900] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
β-Arrestins are crucial regulators of G-protein coupled receptor (GPCR) signaling, desensitization, and internalization. Despite the long-standing paradigm that agonist-promoted receptor phosphorylation is required for β-arrestin2 recruitment, emerging evidence suggests that phosphorylation-independent mechanisms play a role in β-arrestin2 recruitment by GPCRs. Several PDZ proteins are known to interact with GPCRs and serve as cytosolic adaptors to modulate receptor signaling and trafficking. Na(+)/H(+) exchange regulatory factors (NHERFs) exert a major role in GPCR signaling. By combining imaging and biochemical and biophysical methods we investigated the interplay among NHERF1, β-arrestin2, and the parathyroid hormone receptor type 1 (PTHR). We show that NHERF1 and β-arrestin2 can independently bind to the PTHR and form a ternary complex in cultured human embryonic kidney cells and Chinese hamster ovary cells. Although NHERF1 interacts constitutively with the PTHR, β-arrestin2 binding is promoted by receptor activation. NHERF1 interacts directly with β-arrestin2 without using the PTHR as an interface. Fluorescence resonance energy transfer studies revealed that the kinetics of PTHR and β-arrestin2 interactions were modulated by NHERF1. These findings suggest a model in which NHERF1 may serve as an adaptor, bringing β-arrestin2 into close proximity to the PTHR, thereby facilitating β-arrestin2 recruitment after receptor activation.
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Affiliation(s)
- Christoph Klenk
- Institute of Pharmacology and Toxicology, University of Würzburg, 97078 Würzburg, Germany
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8
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Reiner S, Ziegler N, Leon C, Lorenz K, von Hayn K, Gachet C, Lohse MJ, Hoffmann C. beta-Arrestin-2 interaction and internalization of the human P2Y1 receptor are dependent on C-terminal phosphorylation sites. Mol Pharmacol 2009; 76:1162-71. [PMID: 19741005 DOI: 10.1124/mol.109.060467] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The nucleotide receptor P2Y(1) regulates a variety of physiological processes and is involved in platelet aggregation. Using human P2Y(1)-receptors C-terminally fused with a fluorescent protein, we studied the role of potential receptor phosphorylation sites in receptor internalization and beta-arrestin-2 translocation by means of confocal microscopy. Three receptor constructs were generated that lacked potential phosphorylation sites in the third intracellular loop, the proximal C terminus, or the distal C terminus. The corresponding receptor constructs were expressed in human embryonic kidney (HEK)-293 cells and stimulated with 100 muM ADP. Rapid receptor internalization was observed for the wild-type receptor and from those constructs mutated in the third intracellular loop and the proximal C terminus. However, the construct lacking phosphorylation sites at the distal C terminus did not show receptor internalization upon stimulation. The microscopic data were validated by HA-tagged receptor constructs using a cell surface enzyme-linked immunosorbent assay. P2Y(1)-receptor stimulated beta-arrestin-2-yellow fluorescent protein (YFP) translocation followed the same pattern as receptor internalization. Hence, no beta-arrestin-2-YFP translocation was observed when the distal C-terminal phosphorylation sites were mutated. Individual mutations indicate that residues Ser352 and Thr358 are essential for receptor internalization and beta-arrestin-2-YFP translocation. In contrast, protein kinase C (PKC)-mediated receptor desensitization was not affected by mutation of potential phosphorylation sites in the distal C terminus but was prevented by mutation of potential phosphorylation sites in the proximal C terminus. P2Y(1)-receptor internalization in HEK-293 cells was not blocked by inhibitors of PKC and calmodulin-dependent protein kinase. Thus, we conclude that P2Y(1)-receptor desensitization and internalization are mediated by different phosphorylation sites and kinases.
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Affiliation(s)
- Susanne Reiner
- Department of Pharmacology and Toxicology, University of Wuerzburg, Versbacher Str. 9, 97078 Wuerzburg, Germany
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9
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Kong KC, Gandhi U, Martin TJ, Anz CB, Yan H, Misior AM, Pascual RM, Deshpande DA, Penn RB. Endogenous Gs-coupled receptors in smooth muscle exhibit differential susceptibility to GRK2/3-mediated desensitization. Biochemistry 2008; 47:9279-88. [PMID: 18690720 PMCID: PMC2947145 DOI: 10.1021/bi801056w] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Although G protein-coupled receptor (GPCR) kinases (GRKs) have been shown to mediate desensitization of numerous GPCRs in studies using cellular expression systems, their function under physiological conditions is less well understood. In the current study, we employed various strategies to assess the effect of inhibiting endogenous GRK2/3 on signaling and function of endogenously expressed G s-coupled receptors in human airway smooth muscle (ASM) cells. GRK2/3 inhibition by expression of a Gbetagamma sequestrant, a GRK2/3 dominant-negative mutant, or siRNA-mediated knockdown increased intracellular cAMP accumulation mediated via beta-agonist stimulation of the beta-2-adrenergic receptor (beta 2AR). Conversely, neither 5'-( N-ethylcarboxamido)-adenosine (NECA; activating the A2b adenosine receptor) nor prostaglandin E2 (PGE 2; activating EP2 or EP4 receptors)-stimulated cAMP was significantly increased by GRK2/3 inhibition. Selective knockdown using siRNA suggested the majority of PGE 2-stimulated cAMP in ASM was mediated by the EP2 receptor. Although a minor role for EP3 receptors in influencing PGE 2-mediated cAMP was determined, the GRK2/3-resistant nature of EP2 receptor signaling in ASM was confirmed using the EP2-selective agonist butaprost. Somewhat surprisingly, GRK2/3 inhibition did not augment the inhibitory effect of the beta-agonist on mitogen-stimulated increases in ASM growth. These findings demonstrate that with respect to G s-coupled receptors in ASM, GRK2/3 selectively attenuates beta 2AR signaling, yet relief of GRK2/3-dependent beta 2AR desensitization does not influence at least one important physiological function of the receptor.
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Affiliation(s)
- Kok Choi Kong
- Department of Internal Medicine and Center for Human Genomics, Wake Forest University Health Sciences, Winston-Salem, North Carolina 27157
| | - Uma Gandhi
- Department of Internal Medicine and Center for Human Genomics, Wake Forest University Health Sciences, Winston-Salem, North Carolina 27157
| | - T. J. Martin
- Department of Internal Medicine and Center for Human Genomics, Wake Forest University Health Sciences, Winston-Salem, North Carolina 27157
| | - Candace B. Anz
- Department of Internal Medicine and Center for Human Genomics, Wake Forest University Health Sciences, Winston-Salem, North Carolina 27157
| | - Huandong Yan
- Department of Internal Medicine and Center for Human Genomics, Wake Forest University Health Sciences, Winston-Salem, North Carolina 27157
| | - Anna M. Misior
- Department of Internal Medicine and Center for Human Genomics, Wake Forest University Health Sciences, Winston-Salem, North Carolina 27157
| | - Rodolfo M. Pascual
- Department of Internal Medicine and Center for Human Genomics, Wake Forest University Health Sciences, Winston-Salem, North Carolina 27157
| | - Deepak A. Deshpande
- Department of Internal Medicine and Center for Human Genomics, Wake Forest University Health Sciences, Winston-Salem, North Carolina 27157
| | - Raymond B. Penn
- Department of Internal Medicine and Center for Human Genomics, Wake Forest University Health Sciences, Winston-Salem, North Carolina 27157
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Xin W, Tran TM, Richter W, Clark RB, Rich TC. Roles of GRK and PDE4 activities in the regulation of beta2 adrenergic signaling. ACTA ACUST UNITED AC 2008; 131:349-64. [PMID: 18347080 PMCID: PMC2279169 DOI: 10.1085/jgp.200709881] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
An important focus in cell biology is understanding how different feedback mechanisms regulate G protein-coupled receptor systems. Toward this end we investigated the regulation of endogenous beta(2) adrenergic receptors (beta2ARs) and phosphodiesterases (PDEs) by measuring cAMP signals in single HEK-293 cells. We monitored cAMP signals using genetically encoded cyclic nucleotide-gated (CNG) channels. This high resolution approach allowed us to make several observations. (a) Exposure of cells to 1 muM isoproterenol triggered transient increases in cAMP levels near the plasma membrane. Pretreatment of cells with 10 muM rolipram, a PDE4 inhibitor, prevented the decline in the isoproterenol-induced cAMP signals. (b) 1 muM isoproterenol triggered a sustained, twofold increase in phosphodiesterase type 4 (PDE4) activity. (c) The decline in isoproterenol-dependent cAMP levels was not significantly altered by including 20 nM PKI, a PKA inhibitor, or 3 muM 59-74E, a GRK inhibitor, in the pipette solution; however, the decline in the cAMP levels was prevented when both PKI and 59-74E were included in the pipette solution. (d) After an initial 5-min stimulation with isoproterenol and a 5-min washout, little or no recovery of the signal was observed during a second 5-min stimulation with isoproterenol. (e) The amplitude of the signal in response to the second isoproterenol stimulation was not altered when PKI was included in the pipette solution, but was significantly increased when 59-74E was included. Taken together, these data indicate that either GRK-mediated desensitization of beta2ARs or PKA-mediated stimulation of PDE4 activity is sufficient to cause declines in cAMP signals. In addition, the data indicate that GRK-mediated desensitization is primarily responsible for a sustained suppression of beta2AR signaling. To better understand the interplay between receptor desensitization and PDE4 activity in controlling cAMP signals, we developed a mathematical model of this system. Simulations of cAMP signals using this model are consistent with the experimental data and demonstrate the importance of receptor levels, receptor desensitization, basal adenylyl cyclase activity, and regulation of PDE activity in controlling cAMP signals, and hence, on the overall sensitivity of the system.
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Affiliation(s)
- Wenkuan Xin
- Department of Pharmacology, College of Medicine and Center for Lung Biology, University of South Alabama, Mobile, AL 36688, USA
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11
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Tran TM, Jorgensen R, Clark RB. Phosphorylation of the beta2-adrenergic receptor in plasma membranes by intrinsic GRK5. Biochemistry 2007; 46:14438-49. [PMID: 18034461 DOI: 10.1021/bi700922h] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Characterization of the GRKs participating in the phosphorylation of the beta2-adrenergic receptor (beta2AR) have in part been limited by the lack of a simple cell-free assay with membrane-bound beta2AR and GRKs. We describe here a cell-free assay for GRK phosphorylation of the beta2AR in a postnuclear 600g fraction and washed membranes by intrinsic GRK activity using the GRK phosphosite-specific antibody that recognizes pS(355,356). Treatment of these cell-free preparations with 1.0 microM isoproterenol (ISO) caused a rapid maximal 10-15-fold increase in GRK site phosphorylation of the beta2AR (t1/2 = 1 min) with an EC50 for ISO stimulation of approximately 80 nM. Extensively washed plasma membrane fractions retained the 10-15-fold ISO stimulation of GRK site phosphorylation and GRK5 levels while being depleted of GRK2 and GRK6. Stimulation of GRK site phosphorylation by a range of partial agonists correlated well with their intrinsic efficacy for stimulation of adenylyl cyclase. GRK phosphorylation of the beta2AR in the washed membrane fraction caused minimal desensitization of ISO stimulation of adenylyl cyclase activity. Association of GRK5 with the beta2AR in intact cells was demonstrated by a high level of basal BRET2 using beta2AR-Rluc and GRK5-GFP2 that was not diminished by agonist stimulation. BRET2 between the beta2AR-Rluc and GFP2-betaarrestin 2 was increased by agonist, whereas BRET2 between the beta2AR and GRK2-GFP2 was not significant. On the basis of the level of GRK5-mediated phosphorylation we observe in isolated membrane fractions and co-localization of the beta2AR and GRK5, we conclude that GRK5 plays a distinctive role in the phosphorylation of the beta2AR.
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Affiliation(s)
- Tuan M Tran
- The University of Texas Health Science Center Houston, P.O Box 20708, Houston, Texas 77225, USA
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Schutzer WE, Xue H, Reed JF, Mader SL. Effect of age on vascular beta2-adrenergic receptor desensitization is not mediated by the receptor coupling to Galphai proteins. J Gerontol A Biol Sci Med Sci 2006; 61:899-906. [PMID: 16960020 DOI: 10.1093/gerona/61.9.899] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Beta-adrenergic receptor (beta-AR)-mediated vasorelaxation declines with age. In the vasculature, beta2-AR undergoes protein kinase A-mediated desensitization that causes a switch in the G protein coupled to beta2-AR; Galphai links instead of Galphas. We exposed Fischer 344 rat aortae of increasing age to a desensitizing dose of isoproterenol, and determined its effect on beta2-AR-mediated vasorelaxation. Desensitization decreased beta2-AR-mediated vasorelaxation in young aortae only. Subsequently, we used pertussis toxin to block Galphai to determine whether changes in beta2-AR/G protein coupling occurred. Galphai inhibition did not reverse desensitization or the age-related change, but there appears to be a population of beta2-AR linked to Galphai, as pertussis toxin treatment improved beta2-AR-mediated vasorelaxation in aortae from animals of all ages. These findings suggest aortic beta2-AR in older animals may be maximally desensitized, which would explain impaired vasorelaxation. Our results also imply that protein kinase A-mediated beta2-AR desensitization may not be responsible for the age-related decline.
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Barthet G, Gaven F, Framery B, Shinjo K, Nakamura T, Claeysen S, Bockaert J, Dumuis A. Uncoupling and endocytosis of 5-hydroxytryptamine 4 receptors. Distinct molecular events with different GRK2 requirements. J Biol Chem 2005; 280:27924-34. [PMID: 15919661 DOI: 10.1074/jbc.m502272200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The 5-hydroxytryptamine type 4 receptors (5-HT4Rs) are involved in memory, cognition, feeding, respiratory control, and gastrointestinal motility through activation of a G(s)/cAMP pathway. We have shown that 5-HT4R undergoes rapid and profound homologous uncoupling in neurons. However, no significant uncoupling was observed in COS-7 or HEK293 cells, which expressed either no or a weak concentration of GRK2, respectively. High expression of GRK2 in neurons is likely to be the reason for this difference because overexpression of GRK2 in COS-7 and HEK293 cells reproduced rapid and profound uncoupling of 5-HT4R. We have also shown, for the first time, that GRK2 requirements for uncoupling and endocytosis were very different. Indeed, beta-arrestin/dynamin-dependent endocytosis was observed in HEK293 cells without any need of GRK2 overexpression. In addition to this difference, uncoupling and beta-arrestin/dynamin-dependent endocytosis were mediated through distinct mechanisms. Neither uncoupling nor beta-arrestin/dynamin-dependent endocytosis required the serine and threonine residues localized within the specific C-terminal domains of the 5-HT4R splice variants. In contrast, a cluster of serines and threonines, common to all variants, was an absolute requirement for beta-arrestin/dynamin-dependent receptor endocytosis, but not for receptor uncoupling. Furthermore, beta-arrestin/dynamin-dependent endocytosis and uncoupling were dependent on and independent of GRK2 kinase activity, respectively. These results clearly demonstrate that the uncoupling and endocytosis of 5-HT4R require different GRK2 concentrations and involve distinct molecular events.
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MESH Headings
- Alternative Splicing
- Amino Acid Sequence
- Animals
- Arrestins/metabolism
- COS Cells
- Cell Line
- Culture Media, Serum-Free/pharmacology
- Cyclic AMP/metabolism
- Cyclic AMP-Dependent Protein Kinases/chemistry
- Cyclic AMP-Dependent Protein Kinases/physiology
- DNA, Complementary/metabolism
- Dose-Response Relationship, Drug
- Dynamins/metabolism
- Endocytosis
- Enzyme-Linked Immunosorbent Assay
- Genes, Dominant
- Humans
- Immunoblotting
- Mice
- Microscopy, Confocal
- Microscopy, Fluorescence
- Molecular Sequence Data
- Neurons/metabolism
- Plasmids/metabolism
- Protein Binding
- Protein Conformation
- Protein Structure, Tertiary
- RNA/chemistry
- RNA/metabolism
- RNA, Messenger/metabolism
- Receptors, Serotonin, 5-HT4/chemistry
- Reverse Transcriptase Polymerase Chain Reaction
- Serine/chemistry
- Threonine/chemistry
- Time Factors
- Transfection
- beta-Adrenergic Receptor Kinases
- beta-Arrestins
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