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Mangmool S, Parichatikanond W, Kurose H. Therapeutic Targets for Treatment of Heart Failure: Focus on GRKs and β-Arrestins Affecting βAR Signaling. Front Pharmacol 2018; 9:1336. [PMID: 30538631 PMCID: PMC6277550 DOI: 10.3389/fphar.2018.01336] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 10/30/2018] [Indexed: 12/19/2022] Open
Abstract
Heart failure (HF) is a heart disease that is classified into two main types: HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF). Both types of HF lead to significant risk of mortality and morbidity. Pharmacological treatment with β-adrenergic receptor (βAR) antagonists (also called β-blockers) has been shown to reduce the overall hospitalization and mortality rates and improve the clinical outcomes in HF patients with HFrEF but not HFpEF. Although, the survival rate of patients suffering from HF continues to drop, the management of HF still faces several limitations and discrepancies highlighting the need to develop new treatment strategies. Overstimulation of the sympathetic nervous system is an adaptive neurohormonal response to acute myocardial injury and heart damage, whereas prolonged exposure to catecholamines causes defects in βAR regulation, including a reduction in the amount of βARs and an increase in βAR desensitization due to the upregulation of G protein-coupled receptor kinases (GRKs) in the heart, contributing in turn to the progression of HF. Several studies show that myocardial GRK2 activity and expression are raised in the failing heart. Furthermore, β-arrestins play a pivotal role in βAR desensitization and, interestingly, can mediate their own signal transduction without any G protein-dependent pathway involved. In this review, we provide new insight into the role of GRKs and β-arrestins on how they affect βAR signaling regarding the molecular and cellular pathophysiology of HF. Additionally, we discuss the therapeutic potential of targeting GRKs and β-arrestins for the treatment of HF.
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Affiliation(s)
- Supachoke Mangmool
- Department of Pharmacology, Faculty of Pharmacy, Mahidol University, Bangkok, Thailand
| | | | - Hitoshi Kurose
- Department of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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Grisanti LA, Schumacher SM, Tilley DG, Koch WJ. Designer Approaches for G Protein-Coupled Receptor Modulation for Cardiovascular Disease. JACC Basic Transl Sci 2018; 3:550-562. [PMID: 30175279 PMCID: PMC6115700 DOI: 10.1016/j.jacbts.2017.12.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 12/14/2017] [Indexed: 12/17/2022]
Abstract
The new horizon for cardiac therapy may lie beneath the surface, with the downstream mediators of G protein–coupled receptor (GPCR) activity. Targeted approaches have shown that receptor activation may be biased toward signaling through G proteins or through GPCR kinases (GRKs) and β-arrestins, with divergent functional outcomes. In addition to these canonical roles, numerous noncanonical activities of GRKs and β-arrestins have been demonstrated to modulate GPCR signaling at all levels of receptor activation and regulation. Further, research continues to identify novel GRK/effector and β-arrestin/effector complexes with distinct impacts on cardiac function in the normal heart and the diseased heart. Coupled with the identification of once orphan receptors and endogenous ligands with beneficial cardiovascular effects, this expands the repertoire of GPCR targets. Together, this research highlights the potential for focused therapeutic activation of beneficial pathways, with simultaneous exclusion or inhibition of detrimental signaling, and represents a new wave of therapeutic development.
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Key Words
- AR, adrenergic receptor
- AT1R, angiotensin II type 1A receptor
- CRF, corticotropin-releasing factor
- EGFR, epidermal growth factor receptor
- ERK1/2, extracellular signal-regulated kinase
- G protein–coupled receptor kinases
- G protein–coupled receptors
- GPCR, G protein–coupled receptor
- GRK, G protein–coupled receptor kinase
- HF, heart failure
- ICL, intracellular loop
- PI3K, phosphoinositide 3-kinase
- SERCA2a, sarco(endo)plasmic reticulum Ca2+-ATPase
- SII, [Sar(1), Ile (4), Ile(8)]-angiotensin II
- biased ligands
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Affiliation(s)
- Laurel A Grisanti
- Center for Translational Medicine and Department of Pharmacology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania.,Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
| | - Sarah M Schumacher
- Center for Translational Medicine and Department of Pharmacology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania.,Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | - Douglas G Tilley
- Center for Translational Medicine and Department of Pharmacology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Walter J Koch
- Center for Translational Medicine and Department of Pharmacology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
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3
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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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Gurevich EV, Gainetdinov RR, Gurevich VV. G protein-coupled receptor kinases as regulators of dopamine receptor functions. Pharmacol Res 2016; 111:1-16. [PMID: 27178731 DOI: 10.1016/j.phrs.2016.05.010] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 05/03/2016] [Accepted: 05/06/2016] [Indexed: 02/08/2023]
Abstract
Actions of the neurotransmitter dopamine in the brain are mediated by dopamine receptors that belong to the superfamily of G protein-coupled receptors (GPCRs). Mammals have five dopamine receptor subtypes, D1 through D5. D1 and D5 couple to Gs/olf and activate adenylyl cyclase, whereas D2, D3, and D4 couple to Gi/o and inhibit it. Most GPCRs upon activation by an agonist are phosphorylated by GPCR kinases (GRKs). The GRK phosphorylation makes receptors high-affinity binding partners for arrestin proteins. Arrestin binding to active phosphorylated receptors stops further G protein activation and promotes receptor internalization, recycling or degradation, thereby regulating their signaling and trafficking. Four non- visual GRKs are expressed in striatal neurons. Here we describe known effects of individual GRKs on dopamine receptors in cell culture and in the two in vivo models of dopamine-mediated signaling: behavioral response to psychostimulants and L-DOPA- induced dyskinesia. Dyskinesia, associated with dopamine super-sensitivity of striatal neurons, is a debilitating side effect of L-DOPA therapy in Parkinson's disease. In vivo, GRK subtypes show greater receptor specificity than in vitro or in cultured cells. Overexpression, knockdown, and knockout of individual GRKs, particularly GRK2 and GRK6, have differential effects on signaling of dopamine receptor subtypes in the brain. Furthermore, deletion of GRK isoforms in select striatal neuronal types differentially affects psychostimulant-induced behaviors. In addition, anti-dyskinetic effect of GRK3 does not require its kinase activity: it is mediated by the binding of its RGS-like domain to Gαq/11, which suppresses Gq/11 signaling. The data demonstrate that the dopamine signaling in defined neuronal types in vivo is regulated by specific and finely orchestrated actions of GRK isoforms.
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Affiliation(s)
- Eugenia V Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37221, USA.
| | - Raul R Gainetdinov
- Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, 199034, Russia; Skolkovo Institute of Science and Technology, Skolkovo, 143025, Moscow, Russia
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Abstract
G-protein-coupled receptor kinases (GRKs) are serine/threonine protein kinases originally discovered for their role in G-protein-coupled receptor (GPCR) phosphorylation. Recent studies have demonstrated a much broader function for this kinase family including phosphorylation of cytosolic substrates involved in cell signaling pathways stimulated by GPCRs, as well as by non-GPCRs. In addition, GRKs modulate signaling via phosphorylation-independent functions. Because of these various biochemical functions, GRKs have been shown to affect critical physiological and pathophysiological processes, and thus are considered as drug targets in diseases such as heart failure. Role of GRKs in inflammation and inflammatory diseases is an evolving area of research and several studies including work from our lab in the recent years have demonstrated critical role of GRKs in the immune system. In this review, we discuss the classical and the newly emerging functions of GRKs in the immune system and their role in inflammation and disease processes.
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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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Ahmed MR, Bychkov E, Kook S, Zurkovsky L, Dalby KN, Gurevich EV. Overexpression of GRK6 rescues L-DOPA-induced signaling abnormalities in the dopamine-depleted striatum of hemiparkinsonian rats. Exp Neurol 2015; 266:42-54. [PMID: 25687550 DOI: 10.1016/j.expneurol.2015.02.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 01/26/2015] [Accepted: 02/05/2015] [Indexed: 12/26/2022]
Abstract
l-DOPA therapy in Parkinson's disease often results in side effects such as l-DOPA-induced dyskinesia (LID). Our previous studies demonstrated that defective desensitization of dopamine receptors caused by decreased expression of G protein-coupled receptor kinases (GRKs) plays a role. Overexpression of GRK6, the isoform regulating dopamine receptors, in parkinsonian rats and monkeys alleviated LID and reduced LID-associated changes in gene expression. Here we show that 2-fold lentivirus-mediated overexpression of GRK6 in the dopamine-depleted striatum in rats unilaterally lesioned with 6-hydroxydopamine ameliorated supersensitive ERK response to l-DOPA challenge caused by loss of dopamine. A somewhat stronger effect of GRK6 was observed in drug-naïve than in chronically l-DOPA-treated animals. GRK6 reduced the responsiveness of p38 MAP kinase to l-DOPA challenge rendered supersensitive by dopamine depletion. The JNK MAP kinase was unaffected by loss of dopamine, chronic or acute l-DOPA, or GRK6. Overexpressed GRK6 suppressed enhanced activity of Akt in the lesioned striatum by reducing elevated phosphorylation at its major activating residue Thr(308). Finally, GRK6 reduced accumulation of ΔFosB in the lesioned striatum, the effect that paralleled a decrease in locomotor sensitization to l-DOPA in GRK6-expressing rats. The results suggest that elevated GRK6 facilitate desensitization of DA receptors, thereby normalizing of the activity of multiple signaling pathways implicated in LID. Thus, improving the regulation of dopamine receptor function via the desensitization mechanism could be an effective way of managing LID.
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Affiliation(s)
- M Rafiuddin Ahmed
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Evgeny Bychkov
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Seunghyi Kook
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Lilia Zurkovsky
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Kevin N Dalby
- Division of Medicinal Chemistry, University of Texas at Austin, Austin, TX 78712, USA
| | - Eugenia V Gurevich
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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8
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Bojic T, Sudar E, Mikhailidis D, Alavantic D, Isenovic E. The role of G protein coupled receptor kinases in neurocardiovascular pathophysiology. Arch Med Sci 2012; 8:970-7. [PMID: 23319968 PMCID: PMC3542506 DOI: 10.5114/aoms.2012.29996] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 06/14/2012] [Accepted: 06/29/2012] [Indexed: 12/15/2022] Open
Abstract
In coronary artery disease the G protein related kinases (GRKs) play a role in desensitization of β-adrenoreceptors (AR) after coronary occlusion. Targeted deletion and lowering of cardiac myocyte GRK-2 decreases the risk of post-ischemic heart failure (HF). Studies carried out in humans confirm the role of GRK-2 as a marker for the progression of HF after myocardial infarction (MI). The level of GRK-2 could be an indicator of β-AR blocker efficacy in patients with acute coronary syndrome. Elevated levels of GRK-2 are an early ubiquitous consequence of myocardial injury. In hypertension an increased level of GRK-2 was reported in both animal models and human studies. The role of GRKs in vagally mediated disorders such as vasovagal syncope and atrial fibrillation remains controversial. The role of GRKs in the pathogenesis of neurocardiological diseases provides an insight into the molecular pathogenesis process, opens potential therapeutic options and suggests new directins for scientific research.
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Affiliation(s)
- Tijana Bojic
- Institute of Nuclear Sciences Vinča, University of Belgrade, Laboratory of Radiobiology and Molecular Genetics, Belgrade, Serbia
| | - Emina Sudar
- Institute of Nuclear Sciences Vinča, University of Belgrade, Laboratory of Radiobiology and Molecular Genetics, Belgrade, Serbia
| | - Dimitri Mikhailidis
- Department of Clinical Biochemistry (Vascular Disease Prevention Clinics), Royal Free Hospital Campus, University College London Medical School, UK
| | - Dragan Alavantic
- Institute of Nuclear Sciences Vinča, University of Belgrade, Laboratory of Radiobiology and Molecular Genetics, Belgrade, Serbia
| | - Esma Isenovic
- Institute of Nuclear Sciences Vinča, University of Belgrade, Laboratory of Radiobiology and Molecular Genetics, Belgrade, Serbia
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9
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Bychkov E, Zurkovsky L, Garret MB, Ahmed MR, Gurevich EV. Distinct cellular and subcellular distributions of G protein-coupled receptor kinase and arrestin isoforms in the striatum. PLoS One 2012; 7:e48912. [PMID: 23139825 PMCID: PMC3490921 DOI: 10.1371/journal.pone.0048912] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 10/08/2012] [Indexed: 11/18/2022] Open
Abstract
G protein-coupled receptor kinases (GRKs) and arrestins mediate desensitization of G protein-coupled receptors (GPCR). Arrestins also mediate G protein-independent signaling via GPCRs. Since GRK and arrestins demonstrate no strict receptor specificity, their functions in the brain may depend on their cellular complement, expression level, and subcellular targeting. However, cellular expression and subcellular distribution of GRKs and arrestins in the brain is largely unknown. We show that GRK isoforms GRK2 and GRK5 are similarly expressed in direct and indirect pathway neurons in the rat striatum. Arrestin-2 and arrestin-3 are also expressed in neurons of both pathways. Cholinergic interneurons are enriched in GRK2, arrestin-3, and GRK5. Parvalbumin-positive interneurons express more of GRK2 and less of arrestin-2 than medium spiny neurons. The GRK5 subcellular distribution in the human striatal neurons is altered by its phosphorylation: unphosphorylated enzyme preferentially localizes to synaptic membranes, whereas phosphorylated GRK5 is found in plasma membrane and cytosolic fractions. Both GRK isoforms are abundant in the nucleus of human striatal neurons, whereas the proportion of both arrestins in the nucleus was equally low. However, overall higher expression of arrestin-2 yields high enough concentration in the nucleus to mediate nuclear functions. These data suggest cell type- and subcellular compartment-dependent differences in GRK/arrestin-mediated desensitization and signaling.
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Affiliation(s)
| | | | | | | | - Eugenia V. Gurevich
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- * E-mail:
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10
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von Lueder TG, Gravning J, How OJ, Vinge LE, Ahmed MS, Krobert KA, Levy FO, Larsen TS, Smiseth OA, Aasum E, Attramadal H. Cardiomyocyte-restricted inhibition of G protein-coupled receptor kinase-3 attenuates cardiac dysfunction after chronic pressure overload. Am J Physiol Heart Circ Physiol 2012; 303:H66-74. [PMID: 22542621 DOI: 10.1152/ajpheart.00724.2011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Transgenic mice with cardiac-specific expression of a peptide inhibitor of G protein-coupled receptor kinase (GRK)3 [transgenic COOH-terminal GRK3 (GRK3ct) mice] display myocardial hypercontractility without hypertrophy and enhanced α(1)-adrenergic receptor signaling. A role for GRK3 in the pathogenesis of heart failure (HF) has not been investigated, but inhibition of its isozyme, GRK2, has been beneficial in several HF models. Here, we tested whether inhibition of GRK3 modulated evolving cardiac hypertrophy and dysfunction after pressure overload. Weight-matched male GRK3ct transgenic and nontransgenic littermate control (NLC) mice subjected to chronic pressure overload by abdominal aortic banding (AB) were compared with sham-operated (SH) mice. At 6 wk after AB, a significant increase of cardiac mass consistent with induction of hypertrophy was found, but no differences between GRK3ct-AB and NLC-AB mice were discerned. Simultaneous left ventricular (LV) pressure-volume analysis of electrically paced, ex vivo perfused working hearts revealed substantially reduced systolic and diastolic function in NLC-AB mice (n = 7), which was completely preserved in GRK3ct-AB mice (n = 7). An additional cohort was subjected to in vivo cardiac catheterization and LV pressure-volume analysis at 12 wk after AB. NLC-AB mice (n = 11) displayed elevated end-diastolic pressure (8.5 ± 3.1 vs. 2.9 ± 1.2 mmHg, P < 0.05), reduced cardiac output (3,448 ± 323 vs. 4,488 ± 342 μl/min, P < 0.05), and reduced dP/dt(max) and dP/dt(min) (both P < 0.05) compared with GRK3ct-AB mice (n = 16), corroborating the preserved cardiac structure and function observed in GRK3ct-AB hearts assessed ex vivo. Increased cardiac mass and myocardial mRNA expression of β-myosin heavy chain confirmed the similar induction of cardiac hypertrophy in both AB groups, but only NLC-AB hearts displayed significantly elevated mRNA levels of brain natriuretic peptide and myocardial collagen contents as well as reduced β(1)-adrenergic receptor responsiveness to isoproterenol, indicating increased LV wall stress and the transition to HF. Inhibition of cardiac GRK3 in mice does not alter the hypertrophic response but attenuates cardiac dysfunction and HF after chronic pressure overload.
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Affiliation(s)
- Thomas G von Lueder
- Institute for Surgical Research, Oslo University Hospital, Rikshospitalet, Norway
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11
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Abstract
G protein-coupled receptors (GPCRs) represent the largest family of membrane receptors and are responsible for regulating a wide variety of physiological processes. This is accomplished via ligand binding to GPCRs, activating associated heterotrimeric G proteins and intracellular signaling pathways. G protein-coupled receptor kinases (GRKs), in concert with β-arrestins, classically desensitize receptor signal transduction, thus preventing hyperactivation of GPCR second-messenger cascades. As changes in GRK expression have featured prominently in many cardiovascular pathologies, including heart failure, myocardial infarction, hypertension, and cardiac hypertrophy, GRKs have been intensively studied as potential diagnostic or therapeutic targets. Herein, we review our evolving understanding of the role of GRKs in cardiovascular pathophysiology.
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Affiliation(s)
- Stephen L Belmonte
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
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12
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Gurevich EV, Tesmer JJG, Mushegian A, Gurevich VV. G protein-coupled receptor kinases: more than just kinases and not only for GPCRs. Pharmacol Ther 2011; 133:40-69. [PMID: 21903131 DOI: 10.1016/j.pharmthera.2011.08.001] [Citation(s) in RCA: 264] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 08/01/2011] [Indexed: 12/24/2022]
Abstract
G protein-coupled receptor (GPCR) kinases (GRKs) are best known for their role in homologous desensitization of GPCRs. GRKs phosphorylate activated receptors and promote high affinity binding of arrestins, which precludes G protein coupling. GRKs have a multidomain structure, with the kinase domain inserted into a loop of a regulator of G protein signaling homology domain. Unlike many other kinases, GRKs do not need to be phosphorylated in their activation loop to achieve an activated state. Instead, they are directly activated by docking with active GPCRs. In this manner they are able to selectively phosphorylate Ser/Thr residues on only the activated form of the receptor, unlike related kinases such as protein kinase A. GRKs also phosphorylate a variety of non-GPCR substrates and regulate several signaling pathways via direct interactions with other proteins in a phosphorylation-independent manner. Multiple GRK subtypes are present in virtually every animal cell, with the highest expression levels found in neurons, with their extensive and complex signal regulation. Insufficient or excessive GRK activity was implicated in a variety of human disorders, ranging from heart failure to depression to Parkinson's disease. As key regulators of GPCR-dependent and -independent signaling pathways, GRKs are emerging drug targets and promising molecular tools for therapy. Targeted modulation of expression and/or of activity of several GRK isoforms for therapeutic purposes was recently validated in cardiac disorders and Parkinson's disease.
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Affiliation(s)
- Eugenia V Gurevich
- Department of Pharmacology, Vanderbilt University, 2200 Pierce Avenue, Preston Research Building, Rm. 454, Nashville, TN 37232, United States.
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Bychkov ER, Ahmed MR, Gurevich VV, Benovic JL, Gurevich EV. Reduced expression of G protein-coupled receptor kinases in schizophrenia but not in schizoaffective disorder. Neurobiol Dis 2011; 44:248-58. [PMID: 21784156 DOI: 10.1016/j.nbd.2011.07.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 06/14/2011] [Accepted: 07/08/2011] [Indexed: 11/30/2022] Open
Abstract
Alterations of multiple G protein-mediated signaling pathways are detected in schizophrenia. G protein-coupled receptor kinases (GRKs) and arrestins terminate signaling by G protein-coupled receptors exerting a powerful influence on receptor functions. Modifications of arrestin and/or GRKs expression may contribute to schizophrenia pathology. Cortical expression of arrestins and GRKs was measured postmortem in control and subjects with schizophrenia or schizoaffective disorder. Additionally, arrestin/GRK expression was determined in elderly patients with schizophrenia and age-matched control. Patients with schizophrenia, but not schizoaffective disorder, displayed a reduced concentration of arrestin and GRK mRNAs and GRK3 protein. Arrestins and GRK significantly decreased with age. In elderly patients, GRK6 was reduced, with other GRKs and arrestins unchanged. A reduced cortical concentration of GRKs in schizophrenia (resembling that in aging) may result in altered G protein-dependent signaling, thus contributing to prefrontal deficits in schizophrenia. The data suggest distinct molecular mechanisms underlying schizophrenia and schizoaffective disorder.
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Affiliation(s)
- E R Bychkov
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
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14
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Ahmed MR, Bychkov E, Gurevich VV, Benovic JL, Gurevich EV. Altered expression and subcellular distribution of GRK subtypes in the dopamine-depleted rat basal ganglia is not normalized by l-DOPA treatment. J Neurochem 2007; 104:1622-36. [PMID: 17996024 DOI: 10.1111/j.1471-4159.2007.05104.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Dysregulation of dopamine (DA) receptors is believed to underlie Parkinson's disease pathology and l-DOPA-induced motor complications. DA receptors are subject to regulation by G protein-coupled receptor kinases (GRKs) and arrestins. DA lesion with 6-hydroxydopamine caused multiple protein- and brain region-specific changes in the expression of GRKs. In the globus pallidus, all four GRK isoforms (GRK2, 3, 5, 6) were reduced in the lesioned hemisphere. In the caudal caudate-putamen (cCPu) three GRK isoforms (GRK2, 3, 6) were decreased by DA depletion. The decrease in GRK proteins in globus pallidus, but not cCPu, was mirrored by reduction in mRNA. GRK3 protein was reduced in the rostral caudate-putamen (rCPu), whereas other isoforms were either unchanged or up-regulated. GRK6 protein and mRNA were up-regulated in rCPu and nucleus accumbens. l-DOPA (25 mg/kg, twice daily for 10 days) failed to reverse changes caused by DA depletion, whereas D(2)/D(3) agonist pergolide (0.25 mg/kg daily for 10 days) restored normal levels of expression of GRK5 and 6. In rCPu, GRK2 protein was increased in most subcellular fractions by l-DOPA but not by DA depletion alone. Similarly, l-DOPA up-regulated arrestin3 in membrane fractions in both regions. GRK5 was down-regulated by l-DOPA in cCPu in the light membrane fraction, where this isoform is the most abundant. The data suggest that alterations in the expression and subcellular distribution of arrestins and GRKs contribute to pathophysiology of Parkinson's disease. Thus, these proteins may be targets for antiparkinsonian therapy.
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Affiliation(s)
- M Rafiuddin Ahmed
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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15
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Pleger ST, Boucher M, Most P, Koch WJ. Targeting myocardial beta-adrenergic receptor signaling and calcium cycling for heart failure gene therapy. J Card Fail 2007; 13:401-14. [PMID: 17602988 DOI: 10.1016/j.cardfail.2007.01.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Revised: 01/09/2007] [Accepted: 01/11/2007] [Indexed: 01/08/2023]
Abstract
Heart failure (HF) is a leading cause of morbidity and mortality in Western countries and projections reveal that HF incidence in the coming years will rise significantly because of an aging population. Pharmacologic therapy has considerably improved HF treatment during the last 2 decades, but fails to rescue failing myocardium and to increase global cardiac function. Therefore, novel therapeutic approaches to target the underlying molecular defects of ventricular dysfunction and to increase the outcome of patients in HF are needed. Failing myocardium generally exhibits distinct changes in beta-adrenergic receptor (betaAR) signaling and intracellular Ca2+-handling providing opportunities for research. Recent advances in transgenic and gene therapy techniques have presented novel therapeutic strategies to alter myocardial function and to target both betaAR signaling and Ca2+-cycling. In this review, we will discuss functional alterations of the betaAR system and Ca2+-handling in HF as well as corresponding therapeutic strategies. We will then focus on recent in vivo gene therapy strategies using the targeted inhibition of the betaAR kinase (betaARK1 or GRK2) and the restoration of S100A1 protein expression to support the injured heart and to reverse or prevent HF.
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MESH Headings
- Animals
- Calcium/metabolism
- Calcium/physiology
- Cardiomyopathy, Hypertrophic/physiopathology
- Cardiomyopathy, Hypertrophic/therapy
- Disease Models, Animal
- G-Protein-Coupled Receptor Kinase 1/blood
- G-Protein-Coupled Receptor Kinase 1/physiology
- G-Protein-Coupled Receptor Kinase 2
- GTP-Binding Protein alpha Subunits/metabolism
- Genetic Therapy
- Heart Failure/metabolism
- Heart Failure/physiopathology
- Heart Failure/therapy
- Humans
- Myocardial Contraction/physiology
- Myocardium/metabolism
- Myocytes, Cardiac/metabolism
- Phosphorylation
- Protein Serine-Threonine Kinases
- Receptors, Adrenergic, beta/genetics
- Receptors, Adrenergic, beta/metabolism
- Receptors, Adrenergic, beta/physiology
- S100 Proteins/metabolism
- beta-Adrenergic Receptor Kinases/metabolism
- beta-Adrenergic Receptor Kinases/physiology
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Affiliation(s)
- Sven T Pleger
- George Zallie and Family Laboratory for Cardiovascular Gene Therapy, Center for Translational Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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16
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Vinge LE, Andressen KW, Attramadal T, Andersen GØ, Ahmed MS, Peppel K, Koch WJ, Freedman NJ, Levy FO, Skomedal T, Osnes JB, Attramadal H. Substrate specificities of g protein-coupled receptor kinase-2 and -3 at cardiac myocyte receptors provide basis for distinct roles in regulation of myocardial function. Mol Pharmacol 2007; 72:582-91. [PMID: 17573483 DOI: 10.1124/mol.107.035766] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The closely related G protein-coupled receptor kinases GRK2 and GRK3 are both expressed in cardiac myocytes. Although GRK2 has been extensively investigated in terms of regulation of cardiac beta-adrenergic receptors, the substrate specificities of the two GRK isoforms at G protein-coupled receptors (GPCR) are poorly understood. In this study, the substrate specificities of GRK2 and GRK3 at GPCRs that control cardiac myocyte function were determined in fully differentiated adult cardiac myocytes. Concentration-effect relationships of GRK2, GRK3, and their respective competitive inhibitors, GRK2ct and GRK3ct, at endogenous endothelin, alpha(1)-adrenergic, and beta(1)-adrenergic receptor-generated responses in cardiac myocytes were achieved by adenovirus gene transduction. GRK3 and GRK3ct were highly potent and efficient at the endothelin receptors (IC(50) for GRK3, 5 +/- 0.7 pmol/mg of protein; EC(50) for GRK3ct, 2 +/- 0.2 pmol/mg of protein). The alpha(1)-adrenergic receptor was also a preferred substrate of GRK3 (IC(50),7 +/- 0.4 pmol/mg of protein). GRK2 lacked efficacy at both endothelin and alpha(1)-adrenergic receptors despite massive overexpression. On the contrary, both GRK2ct and GRK3ct enhanced beta(1)-adrenergic receptor-induced cAMP production with comparable potencies. However, the potency of GRK3ct at beta(1)-adrenergic receptors was at least 20-fold lower than that at endothelin receptors. In conclusion, this study demonstrates distinct substrate specificities of GRK2 and GRK3 at different GPCRs in fully differentiated adult cardiac myocytes. As inferred from the above findings, GRK2 may play its primary role in regulation of cardiac contractility and chronotropy by controlling beta(1)-adrenergic receptors, whereas GRK3 may play important roles in regulation of cardiac growth and hypertrophy by selectively controlling endothelin and alpha(1)-adrenergic receptors.
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MESH Headings
- Adenoviridae/genetics
- Animals
- Cells, Cultured
- G-Protein-Coupled Receptor Kinase 2
- G-Protein-Coupled Receptor Kinase 3
- Gene Expression Regulation, Enzymologic
- Genes, Reporter
- Inhibitory Concentration 50
- Isoenzymes/genetics
- Isoenzymes/metabolism
- Male
- Myocardium/cytology
- Myocardium/enzymology
- Myocytes, Cardiac/metabolism
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-1/genetics
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Adrenergic, beta-1/genetics
- Receptors, Adrenergic, beta-1/metabolism
- Receptors, Endothelin/metabolism
- Substrate Specificity
- Transduction, Genetic
- beta-Adrenergic Receptor Kinases/analysis
- beta-Adrenergic Receptor Kinases/genetics
- beta-Adrenergic Receptor Kinases/metabolism
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Affiliation(s)
- Leif Erik Vinge
- Institute for Surgical Research, Rikshospitalet-Radiumhospitalet Medical Center, University of Oslo, Oslo, Norway
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17
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de Borst MH, Diks SH, Bolbrinker J, Schellings MW, van Dalen MBA, Peppelenbosch MP, Kreutz R, Pinto YM, Navis G, van Goor H. Profiling of the renal kinome: a novel tool to identify protein kinases involved in angiotensin II-dependent hypertensive renal damage. Am J Physiol Renal Physiol 2007; 293:F428-37. [PMID: 17429032 DOI: 10.1152/ajprenal.00367.2006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Regulation of protein kinase activities is crucial in both physiology and disease, but analysis is hampered by the multitude and complexity of kinase networks. We used novel peptide array chips containing 1,152 known kinase substrate sequences to profile different kinase activities in renal lysates from homozygous Ren2 rats, a model characterized by hypertension and angiotensin II (ANG II)-mediated renal fibrosis, compared with Sprague-Dawley (SD) control rats and Ren2 rats treated with an angiotensin-converting enzyme inhibitor (ACEi). Five-wk-old homozygous Ren2 rats were left untreated or treated with the ACEi ramipril (1 mg.kg(-1).day(-1)) for 4 wk; age-matched SD rats served as controls (n = 5 each). Peptide array chips were incubated with renal cortical lysates in the presence of radioactively labeled ATP. Radioactivity incorporated into the substrate motifs was measured to quantify kinase activity. A number of kinases with modulated activities, which might contribute to renal damage, were validated by Western blotting, immunoprecipitation, and immunohistochemistry. Relevant kinases identified by the peptide array and confirmed using conventional techniques included p38 MAP kinase and PDGF receptor-beta, which were increased in Ren2 and reversed by ACEi. Furthermore, insulin receptor signaling was reduced in Ren2 compared with control rats, and G protein-coupled receptor kinase (GRK) activity decreased in Ren2 + ACEi compared with untreated Ren2 rats. Array-based profiling of tissue kinase activities in ANG II-mediated renal damage provides a powerful tool for identification of relevant kinase pathways in vivo and may lead to novel strategies for therapy.
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Affiliation(s)
- Martin H de Borst
- Dept. of Pathology, University of Groningen, University Medical Center Groningen, PO Box 30.001, 9700 RB Groningen, The Netherlands.
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18
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ER B, VV G, JN J, JL B, EV G. Arrestins and two receptor kinases are upregulated in Parkinson's disease with dementia. Neurobiol Aging 2006; 29:379-96. [PMID: 17125886 PMCID: PMC2275668 DOI: 10.1016/j.neurobiolaging.2006.10.012] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2006] [Revised: 09/04/2006] [Accepted: 10/11/2006] [Indexed: 10/23/2022]
Abstract
Arrestins and G proteins-coupled receptor kinases (GRKs) regulate signaling and trafficking of G protein-coupled receptors. We investigated changes in the expression of arrestins and GRKs in the striatum of patients with Parkinson's disease without (PD) or with dementia (PDD) at postmortem using Western blotting and ribonuclease protection assay. Both PD and PDD groups had similar degree of dopamine depletion in all striatal regions. Arrestin proteins and mRNAs were increased in the PDD group throughout striatum. Protein and mRNA of GRK5, the major subtype in the human striatum, and GRK3 were also upregulated, whereas GRK2 and 6 were mostly unchanged. The PD group had lower concentration of arrestins and GRKs than the PDD group. There was no statistical link between the load of Alzheimer's pathology and the expression of these signaling proteins. Upregulation of arrestins and GRK in PDD may confer resistance to the therapeutic effects of levodopa often observed in these patients. In addition, increased arrestin and GRK concentrations may lead to dementia via perturbation of multiple signaling mechanisms.
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Affiliation(s)
- Bychkov ER
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Laboratory of Neuroimmunology, Institute of Human Brain, St. Petersburg 197376, Russia
| | - Gurevich VV
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Joyce JN
- Parkinson's Disease Research Center, Sun Health Research Institute, Sun City, AZ 85351, USA
| | - Benovic JL
- Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Gurevich EV
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Correspondence to: E.V.Gurevich, Department of Pharmacology, Vanderbilt University Medical Center, Preston Research Building Room 422, Nashville, TN 37232. Phone: 1−615−936−2720. FAX: 1−615−343−6532. E-mail:
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19
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Saito T, Bunnett NW. Protease-activated receptors: regulation of neuronal function. Neuromolecular Med 2005; 7:79-99. [PMID: 16052040 DOI: 10.1385/nmm:7:1-2:079] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2004] [Revised: 02/13/2005] [Accepted: 02/17/2005] [Indexed: 12/20/2022]
Abstract
Certain serine proteases from the circulation (e.g., coagulation factors), inflammatory cells (e.g., mast-cell tryptase, neutrophil proteinase 3), and from many other cell types (e.g., trypsins) can specifically signal to cells by cleaving protease-activated receptors (PARs), a family of four G protein-coupled receptors. Proteases cleave PARs at specific sites within the extracellular amino-terminus to expose amino-terminal tethered ligand domains that bind to and activate the cleaved receptors. The proteases that activate PARs are often generated and released during injury and inflammation, and activated PARs orchestrate tissue responses to injury, including hemostasis, inflammation, pain, and repair. This review concerns protease and PAR signaling in the nervous system. Neurons of the central and peripheral nervous systems express all four PARs. Proteases that may derive from the circulation, inflammatory cells, or neural tissues can cleave PARs on neurons and thereby activate diverse signaling pathways that control survival, morphology, release of neurotransmitters, and activity of ion channels. In this manner proteases and PARs regulate neurodegeneration, neurogenic inflammation, and pain transmission. Thus, PARs may participate in disease states and PAR antagonists or agonists may be useful therapies for certain disorders.
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Affiliation(s)
- Toshiyuki Saito
- Department of Surgery, University of California, San Francisco, CA, USA
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20
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Hartley CJ, Reddy AK, Madala S, Entman ML, Michael LH, Taffet GE. Noninvasive ultrasonic measurement of arterial wall motion in mice. Am J Physiol Heart Circ Physiol 2004; 287:H1426-32. [PMID: 15317682 DOI: 10.1152/ajpheart.01185.2003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Despite the extensive use of genetically altered mice to study cardiovascular physiology and pathology, it remains difficult to quantify arterial function noninvasively in vivo. We have developed a noninvasive Doppler method for quantifying vessel wall motion in anesthetized mice. A 20-MHz probe was held by an alligator clip and positioned over the carotid arteries of 16 mice, including six 3- to 5-mo-old wild-type (WT), four 30-mo-old senescent (old), two apolipoprotein E null (ApoE), and four α-smooth muscle actin null (α-SMA) mice. Doppler signals were obtained simultaneously from both vessel walls and from blood flow. The calculated displacement signals from the near and far walls were subtracted to generate a diameter signal from which the excursion and an augmentation index were calculated. The excursion ranged between 13 μm (in ApoE) and 95 μm (in α-SMA). The augmentation index was lowest in the WT mice (0.06) and highest in the old mice (0.29). We conclude that Doppler signal processing may be used to measure vessel wall motion in mice with high spatial and temporal resolution and that diameter signals can replace pressure signals for calculating the augmentation index. This noninvasive method is able to identify and confirm characteristic changes in arterial properties previously associated with age, atherosclerosis, and the absence of vascular tone.
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Affiliation(s)
- Craig J Hartley
- Department of Medicine, The Methodist DeBakey Heart Center, Baylor College of Medicine, Houston, Texas 77030, USA.
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21
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Yue Y, Skimming JW, Liu M, Strawn T, Duan D. Full-length dystrophin expression in half of the heart cells ameliorates beta-isoproterenol-induced cardiomyopathy in mdx mice. Hum Mol Genet 2004; 13:1669-75. [PMID: 15190010 PMCID: PMC2431460 DOI: 10.1093/hmg/ddh174] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Gene therapy holds great promise for curing Duchenne muscular dystrophy (DMD), the most common fatal inherited childhood muscle disease. Success of DMD gene therapy depends upon functional improvement in both skeletal and cardiac muscle. Numerous gene transfer studies have been performed to correct skeletal muscle pathology, yet little is known about cardiomyopathy gene therapy. Since complete transduction of the entire heart is an impractical goal, it becomes critical to determine the minimal level of correction needed for successful DMD cardiomyopathy gene therapy. To address this question, we generated heterozygous mice that persistently expressed the full-length dystrophin gene in 50% of the cardiomyocytes of mdx mice, a model for DMD. We questioned whether dystrophin expression in half of the heart cells was sufficient to prevent stress-induced cardiomyopathy. Heart function of mdx mouse is normal in the absence of external stress. To determine the therapeutic effect, we challenged 3-month-old mice with beta-isoproterenol. Cardiomyocyte sarcolemma integrity was significantly impaired in mdx but not in heterozygous and C57Bl/10 mice. Importantly, in vivo closed-chest hemodynamic assays revealed normal left ventricular function in beta-isoproterenol-stimulated heterozygous mice. Since the expression profile in the heterozygous mice mimicked viral transduction, we conclude that gene therapy correction in 50% of the heart cells may be sufficient to treat cardiomyopathy in mdx mice. This finding may also apply to the gene therapy of other inherited cardiomyopathies.
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Affiliation(s)
- Yongping Yue
- Department of Molecular Microbiology and Immunology, The University of Missouri, School of Medicine, Columbia 65212, USA
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22
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Abstract
Proteases acting at the surface of cells generate and destroy receptor agonists and activate and inactivate receptors, thereby making a vitally important contribution to signal transduction. Certain serine proteases that derive from the circulation (e.g., coagulation factors), inflammatory cells (e.g., mast cell and neutrophil proteases), and from multiple other sources (e.g., epithelial cells, neurons, bacteria, fungi) can cleave protease-activated receptors (PARs), a family of four G protein-coupled receptors. Cleavage within the extracellular amino terminus exposes a tethered ligand domain, which binds to and activates the receptors to initiate multiple signaling cascades. Despite this irreversible mechanism of activation, signaling by PARs is efficiently terminated by receptor desensitization (receptor phosphorylation and uncoupling from G proteins) and downregulation (receptor degradation by cell-surface and lysosomal proteases). Protease signaling in tissues depends on the generation and release of proteases, availability of cofactors, presence of protease inhibitors, and activation and inactivation of PARs. Many proteases that activate PARs are produced during tissue damage, and PARs make important contributions to tissue responses to injury, including hemostasis, repair, cell survival, inflammation, and pain. Drugs that mimic or interfere with these processes are attractive therapies: selective agonists of PARs may facilitate healing, repair, and protection, whereas protease inhibitors and PAR antagonists can impede exacerbated inflammation and pain. Major future challenges will be to understand the role of proteases and PARs in physiological control mechanisms and human diseases and to develop selective agonists and antagonists that can be used to probe function and treat disease.
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23
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Wang X, Wang J, Takeda S, Elimban V, Dhalla NS. Alterations of cardiac beta-adrenoceptor mechanisms due to calcium depletion and repletion. Mol Cell Biochem 2002; 232:63-73. [PMID: 12030381 DOI: 10.1023/a:1014845300488] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In order to understand the modification of beta-adrenoceptor linked signal transduction by changes in the intracellular Ca2+, we examined the status of beta-adrenoceptors (beta-ARs), G-proteins and adenylyl cyclase (AC) in Ca2+-deficiency and Ca2+-overload by perfusing the isolated rat heart with Ca2+-free medium for 5 min and Ca2+-containing medium for 5 min following Ca2+-free perfusion, respectively. Ca2+-depletion caused not only an increase in basal, isoproterenol-, Gpp(NH)p-, NaF- and forskolin-stimulated AC activities but also produced an increase in the beta1-AR affinity and density as well as up-regulation of G(s)-protein function and uncoupling of G(i)-protein to AC. Ca2+-repletion for 5 min following 5 min Ca2+-free perfusion reversed the increased AC activities to varying degrees. The beta1-AR affinity was further increased upon Ca2+-repletion whereas its density was decreased. Ca2+-repletion also decreased protein content for AC and beta-AR kinase but augmented the changes in G(s)- and G(i)-protein functions. Although low Na+ medium perfusion during Ca2+-depletion prevented the changes in G-proteins during both Ca2+-depletion and Ca2+-repletion periods, the increased beta1-AR affinity and density as well as changes in AC activities due to Ca2+-depletion were not affected while alterations due to Ca2+-repletion were fully prevented. These results suggest that changes in Ca2+-homeostasis may represent a mechanism for alterations in the beta-adrenergic signal transduction pathway in the heart under pathological conditions.
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Affiliation(s)
- Xi Wang
- Institute of Cardiovascular Sciences, St Boniface General Hospital Research Centre and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
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24
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Vinge LE, Øie E, Andersson Y, Grøgaard HK, Andersen G, Attramadal H. Myocardial distribution and regulation of GRK and beta-arrestin isoforms in congestive heart failure in rats. Am J Physiol Heart Circ Physiol 2001; 281:H2490-9. [PMID: 11709416 DOI: 10.1152/ajpheart.2001.281.6.h2490] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Myocardial G protein-coupled receptor kinase 2 (GRK2) has been shown to be involved in the pathophysiology of congestive heart failure (CHF). However, the cellular distribution of this isoform, as well as the other isoforms of the GRK-arrestin system, has not been studied in myocardial tissue. Thus myocardial expression and cellular distribution of the different GRK and arrestin isoforms were investigated in a rat model of CHF. Rats subjected to ligation of the left coronary artery or sham operation were euthanized 2, 7, or 42 days after the surgical procedure. Myocardial GRK2, GRK5, beta-arrestin-1, and beta-arrestin-2 mRNA levels, but not that of GRK3, were induced in the failing hearts. Consistently, Western blot analysis of tissue extracts from the nonischemic region of the left ventricle revealed 3.0-, 2.6-, and 1.5-fold elevations of GRK2, GRK5, and beta-arrestin-1, respectively, 7 days after induction of myocardial infarction compared with the sham-operated rats (P < 0.05). Immunohistochemical analysis of myocardial tissue sections and Western blot analysis of isolated cells revealed localization of GRK2 and beta-arrestin-1 predominantly in endothelial cells. Conversely, GRK3 was confined to cardiac myocytes. GRK5 immunostaining appeared to be homogeneously distributed in the cellular elements of the myocardium. In conclusion, myocardial mRNA and protein levels of GRK2, GRK5, and beta-arrestin-1 are induced in postinfarction failure in rats. The immunohistochemical analysis suggests that GRK2 and beta-arrestin-1 may act as primary regulators of endothelial function. Conversely, the cellular distribution of GRK3 and GRK5 implicates these isoforms as putative regulators of cardiac myocyte function.
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Affiliation(s)
- L E Vinge
- Institute for Surgical Research, Rikshospitalet University Hospital, University of Oslo, N-0027 Oslo, Norway
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25
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Abstract
The four PAR family members are G protein coupled receptors that are normally activated by proteolytic exposure of an occult tethered ligand. Three of the family members are thrombin receptors. The fourth (PAR2) is not activated by thrombin, but can be activated by other proteases, including trypsin, tryptase and Factor Xa. This review focuses on recent information about the manner in which signaling through these receptors is initiated and terminated, including evidence for inter- as well as intramolecular modes of activation, and continuing efforts to identify additional, biologically-relevant proteases that can activate PAR family members.
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Affiliation(s)
- P J O'Brien
- Department of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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26
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Koch WJ, Lefkowitz RJ, Rockman HA. Functional consequences of altering myocardial adrenergic receptor signaling. Annu Rev Physiol 2000; 62:237-60. [PMID: 10845091 DOI: 10.1146/annurev.physiol.62.1.237] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
From the ability to successfully manipulate the mouse genome has come important transgenic and gene-targeted knockout models that impact many areas of biomedical research. Genetically engineered mouse models geared toward the study of cardiovascular regulation have recently been described and provide powerful tools to study normal and compromised cardiac physiology. The genetic manipulation of the adrenergic receptor (AR) signaling system in the heart, including its regulation by desensitizing kinases, has shed light on the role of this signaling pathway in the regulation of cardiac contractility. One major finding, supported by several mouse models, is that in vivo contractility can be enhanced via alteration of myocardial AR signaling. Thus genetic manipulation of this critical receptor system in the heart represents a novel therapeutic approach for improving function of the failing heart.
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Affiliation(s)
- W J Koch
- Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA.
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27
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Abstract
G-protein coupled receptors (GPCRs) comprise one of the largest classes of signalling molecules. A wide diversity of activating ligands induce the active conformation of GPCRs and lead to signalling via heterotrimeric G-proteins and downstream effectors. In addition, a complex series of reactions participate in the 'turn-off' of GPCRs in both physiological and pharmacological settings. Some key players in the inactivation or 'desensitization' of GPCRs have been identified, whereas others remain the target of ongoing studies. G-protein coupled receptor kinases (GRKs) specifically phosphorylate activated GPCRs and initiate homologous desensitization. Uncoupling proteins, such as members of the arrestin family, bind to the phosphorylated and activated GPCRs and cause desensitization by precluding further interactions of the GPCRs and G-proteins. Adaptor proteins, including arrestins, and endocytic machinery participate in the internalization of GPCRs away from their normal signalling milieu. In this review we discuss the roles of these regulatory molecules as modulators of GPCR signalling.
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Affiliation(s)
- M Bünemann
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, 303 East Chicago Avenue S215, Chicago, IL 60611, USA
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