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Du L, Yue H, Rorabaugh BR, Li OQY, DeHart AR, Toloza‐Alvarez G, Hong L, Denvir J, Thompson E, Li W. Thymidine Phosphorylase Deficiency or Inhibition Preserves Cardiac Function in Mice With Acute Myocardial Infarction. J Am Heart Assoc 2023; 12:e028023. [PMID: 36974758 PMCID: PMC10122909 DOI: 10.1161/jaha.122.028023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 02/22/2023] [Indexed: 03/29/2023]
Abstract
Background Ischemic cardiovascular disease is the leading cause of death worldwide. Current pharmacologic therapy has multiple limitations, and patients remain symptomatic despite maximal medical therapies. Deficiency or inhibition of thymidine phosphorylase (TYMP) in mice reduces thrombosis, suggesting that TYMP could be a novel therapeutic target for patients with acute myocardial infarction (AMI). Methods and Results A mouse AMI model was established by ligation of the left anterior descending coronary artery in C57BL/6J wild-type and TYMP-deficient (Tymp-/-) mice. Cardiac function was monitored by echocardiography or Langendorff assay. TYMP-deficient hearts had lower baseline contractility. However, cardiac function, systolic left ventricle anterior wall thickness, and diastolic wall strain were significantly greater 4 weeks after AMI compared with wild-type hearts. TYMP deficiency reduced microthrombus formation after AMI. TYMP deficiency did not affect angiogenesis in either normal or infarcted myocardium but increased arteriogenesis post-AMI. TYMP deficiency enhanced the mobilization of bone marrow stem cells and promoted mesenchymal stem cell (MSC) proliferation, migration, and resistance to inflammation and hypoxia. TYMP deficiency increased the number of larger MSCs and decreased matrix metalloproteinase-2 expression, resulting in a high homing capability. TYMP deficiency induced constitutive AKT phosphorylation in MSCs but reduced expression of genes associated with retinoid-interferon-induced mortality-19, a molecule that enhances cell death. Inhibition of TYMP with its selective inhibitor, tipiracil, phenocopied TYMP deficiency, improved post-AMI cardiac function and systolic left ventricle anterior wall thickness, attenuated diastolic stiffness, and reduced infarct size. Conclusions This study demonstrated that TYMP plays an adverse role after AMI. Targeting TYMP may be a novel therapy for patients with AMI.
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Affiliation(s)
- Lili Du
- Department of Biomedical SciencesJoan C. Edwards School of Medicine at Marshall UniversityHuntingtonWVUSA
- Department of PathophysiologyCollege of Basic Medical Science, China Medical UniversityShenyangLiaoningChina
| | - Hong Yue
- Department of Biomedical SciencesJoan C. Edwards School of Medicine at Marshall UniversityHuntingtonWVUSA
| | - Boyd R. Rorabaugh
- Department of Biomedical SciencesJoan C. Edwards School of Medicine at Marshall UniversityHuntingtonWVUSA
- Department of Pharmaceutical SciencesSchool of Pharmacy at Marshall UniversityHuntingtonWVUSA
| | - Oliver Q. Y. Li
- Department of Biomedical SciencesJoan C. Edwards School of Medicine at Marshall UniversityHuntingtonWVUSA
| | - Autumn R. DeHart
- Department of Biomedical SciencesJoan C. Edwards School of Medicine at Marshall UniversityHuntingtonWVUSA
| | - Gretel Toloza‐Alvarez
- Department of Biomedical SciencesJoan C. Edwards School of Medicine at Marshall UniversityHuntingtonWVUSA
| | - Liang Hong
- Department of Biomedical SciencesJoan C. Edwards School of Medicine at Marshall UniversityHuntingtonWVUSA
| | - James Denvir
- Department of Biomedical SciencesJoan C. Edwards School of Medicine at Marshall UniversityHuntingtonWVUSA
| | - Ellen Thompson
- Department of MedicineJoan C. Edwards School of Medicine at Marshall UniversityHuntingtonWVUSA
| | - Wei Li
- Department of Biomedical SciencesJoan C. Edwards School of Medicine at Marshall UniversityHuntingtonWVUSA
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Soares ROS, Losada DM, Jordani MC, Évora P, Castro-E-Silva O. Ischemia/Reperfusion Injury Revisited: An Overview of the Latest Pharmacological Strategies. Int J Mol Sci 2019; 20:ijms20205034. [PMID: 31614478 PMCID: PMC6834141 DOI: 10.3390/ijms20205034] [Citation(s) in RCA: 185] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/03/2019] [Accepted: 10/08/2019] [Indexed: 02/08/2023] Open
Abstract
Ischemia/reperfusion injury (IRI) permeates a variety of diseases and is a ubiquitous concern in every transplantation proceeding, from whole organs to modest grafts. Given its significance, efforts to evade the damaging effects of both ischemia and reperfusion are abundant in the literature and they consist of several strategies, such as applying pre-ischemic conditioning protocols, improving protection from preservation solutions, thus providing extended cold ischemia time and so on. In this review, we describe many of the latest pharmacological approaches that have been proven effective against IRI, while also revisiting well-established concepts and presenting recent pathophysiological findings in this ever-expanding field. A plethora of promising protocols has emerged in the last few years. They have been showing exciting results regarding protection against IRI by employing drugs that engage several strategies, such as modulating cell-surviving pathways, evading oxidative damage, physically protecting cell membrane integrity, and enhancing cell energetics.
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Affiliation(s)
| | - Daniele M Losada
- Department of Anatomic Pathology, Faculty of Medical Sciences, University of Campinas, 13083-970 Campinas, Brazil.
| | - Maria C Jordani
- Department of Surgery & Anatomy, Ribeirão Preto Medical School, University of São Paulo, 14049-900 Ribeirão Preto, Brazil.
| | - Paulo Évora
- Department of Surgery & Anatomy, Ribeirão Preto Medical School, University of São Paulo, 14049-900 Ribeirão Preto, Brazil.
- Department of Gastroenterology, São Paulo Medical School, University of São Paulo, 01246-903 São Paulo, Brazil.
| | - Orlando Castro-E-Silva
- Department of Surgery & Anatomy, Ribeirão Preto Medical School, University of São Paulo, 14049-900 Ribeirão Preto, Brazil.
- Department of Gastroenterology, São Paulo Medical School, University of São Paulo, 01246-903 São Paulo, Brazil.
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Sun Q, He Q, Xu J, Liu Q, Lu Y, Zhang Z, Xu X, Sun B. Guanine nucleotide-binding protein G(i)α2 aggravates hepatic ischemia-reperfusion injury in mice by regulating MLK3 signaling. FASEB J 2019; 33:7049-7060. [PMID: 30840837 DOI: 10.1096/fj.201802462r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2023]
Abstract
Hepatic ischemia-reperfusion (I/R) injury is a major challenge in liver resection and transplantation surgeries. Previous studies have revealed that guanine nucleotide-binding protein G(i)α2 (GNAI2) was involved in the progression of myocardial and cerebral I/R injury, but the role and function of GNAI2 in hepatic I/R have not been elucidated. The hepatocyte-specific GNAI2 knockout (GNAI2hep-/-) mice were generated and subjected to hepatic I/R injury. Primary hepatocytes isolated from GNAI2hep-/- and GNAI2flox/flox mice were cultured and challenged to hypoxia-reoxygenation insult. The specific function of GNAI2 in I/R-triggered hepatic injury and the underlying molecular mechanism were explored by various phenotypic analyses and molecular biology methods. In this study, we demonstrated that hepatic GNAI2 expression was significantly increased in liver transplantation patients and wild-type mice after hepatic I/R. Interestingly, hepatocyte-specific GNAI2 deficiency attenuated I/R-induced liver damage, inflammation cytokine expression, macrophage/neutrophil infiltration, and hepatocyte apoptosis in vivo and in vitro. Mechanistically, up-regulation of GNAI2 phosphorylates mixed-lineage protein kinase 3 (MLK3) through direct binding, which exacerbated hepatic I/R damage via MAPK and NF-κB pathway activation. Furthermore, blocking MLK3 signaling reversed GNAI2-mediated hepatic I/R injury. Our study firstly identifies GNAI2 as a promising target for prevention of hepatic I/R-induced injury and related liver diseases.-Sun, Q., He, Q., Xu, J., Liu, Q., Lu, Y., Zhang, Z., Xu, X., Sun, B. Guanine nucleotide-binding protein G(i)α2 aggravates hepatic ischemia-reperfusion injury in mice by regulating MLK3 signaling.
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Affiliation(s)
- Qikai Sun
- The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- Department of Hepatobiliary Surgery, Nanjing Drum Tower Hospital, Clinical College of Nanjing Medical University, Nanjing, China; and
- Department of Hepatobiliary Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Qifeng He
- The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- Department of Hepatobiliary Surgery, Nanjing Drum Tower Hospital, Clinical College of Nanjing Medical University, Nanjing, China; and
- Department of Hepatobiliary Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Jianbo Xu
- The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- Department of Hepatobiliary Surgery, Nanjing Drum Tower Hospital, Clinical College of Nanjing Medical University, Nanjing, China; and
- Department of Hepatobiliary Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Qiaoyu Liu
- Department of Hepatobiliary Surgery, Nanjing Drum Tower Hospital, Clinical College of Nanjing Medical University, Nanjing, China; and
- Department of Hepatobiliary Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Yijun Lu
- The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- Department of Hepatobiliary Surgery, Nanjing Drum Tower Hospital, Clinical College of Nanjing Medical University, Nanjing, China; and
- Department of Hepatobiliary Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Zechuan Zhang
- The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- Department of Hepatobiliary Surgery, Nanjing Drum Tower Hospital, Clinical College of Nanjing Medical University, Nanjing, China; and
- Department of Hepatobiliary Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Xiaoliang Xu
- Department of Hepatobiliary Surgery, Nanjing Drum Tower Hospital, Clinical College of Nanjing Medical University, Nanjing, China; and
- Department of Hepatobiliary Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Beicheng Sun
- The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- Department of Hepatobiliary Surgery, Nanjing Drum Tower Hospital, Clinical College of Nanjing Medical University, Nanjing, China; and
- Department of Hepatobiliary Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
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Hwang IY, Park C, Harrison K, Kehrl JH. Normal Thymocyte Egress, T Cell Trafficking, and CD4 + T Cell Homeostasis Require Interactions between RGS Proteins and Gα i2. THE JOURNAL OF IMMUNOLOGY 2017; 198:2721-2734. [PMID: 28235863 DOI: 10.4049/jimmunol.1601433] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 01/24/2017] [Indexed: 11/19/2022]
Abstract
Adaptive immunity depends on mature thymocytes leaving the thymus to enter the bloodstream and the trafficking of T cells through lymphoid organs. Both of these require heterotrimeric Gαi protein signaling, whose intensity and duration are controlled by the regulator of G protein signaling (RGS) proteins. In this study, we show that RGS protein/Gαi2 interactions are essential for normal thymocyte egress, T cell trafficking, and homeostasis. Mature thymocytes with a Gαi2 mutation that disables RGS protein binding accumulated in the perivascular channels of thymic corticomedullary venules. Severe reductions in peripheral naive CD4+ T cells and regulatory T cells occurred. The mutant CD4+ T cells adhered poorly to high endothelial venules and exhibited defects in lymph node entrance and egress. The kinetics of chemokine receptor signaling were disturbed, including chemokine- induced integrin activation. Despite the thymic and lymph node egress defects, sphingosine-1-phosphate signaling was not obviously perturbed. This study reveals how RGS proteins modulate Gαi2 signaling to facilitate thymocyte egress and T cell trafficking.
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Affiliation(s)
- Il-Young Hwang
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Chung Park
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Kathleen Harrison
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - John H Kehrl
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
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Rorabaugh BR, Chakravarti B, Mabe NW, Seeley SL, Bui AD, Yang J, Watts SW, Neubig RR, Fisher RA. Regulator of G Protein Signaling 6 Protects the Heart from Ischemic Injury. J Pharmacol Exp Ther 2016; 360:409-416. [PMID: 28035008 DOI: 10.1124/jpet.116.238345] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 12/28/2016] [Indexed: 01/07/2023] Open
Abstract
Gαi-coupled receptors play important roles in protecting the heart from ischemic injury. Regulator of G protein signaling (RGS) proteins suppress Gαi signaling by accelerating the GTPase activity of Gαi subunits. However, the roles of individual RGS proteins in modulating ischemic injury are unknown. In this study, we investigated the effect of RGS6 deletion on myocardial sensitivity to ischemic injury. Hearts from RGS6 knockout (RGS6-/-) and RGS6 wild-type (RGS6+/+) mice were subjected to 30 minutes of ischemia and 2 hours of reperfusion on a Langendorff heart apparatus. Infarcts in RGS6-/- hearts were significantly larger than infarcts in RGS6+/+ hearts. RGS6-/- hearts also exhibited increased phosphorylation of β2-adrenergic receptors and G protein-coupled receptor kinase 2 (GRK2). Mitochondrial GRK2 as well as caspase-3 cleavage were increased significantly in RGS6-/- hearts compared with RGS6+/+ hearts after ischemia. Chronic propranolol treatment of mice prevented the observed increases in ischemic injury and the GRK2 phosphorylation observed in RGS6-/- hearts. Our findings suggest that loss of RGS6 predisposes the ventricle to prodeath signaling through a β2AR-GRK2-dependent signaling mechanism, and they provide evidence for a protective role of RGS6 in the ischemic heart. Individuals expressing genetic polymorphisms that suppress the activity of RGS6 may be at increased risk of cardiac ischemic injury. Furthermore, the development of agents that increase RGS6 expression or activity might provide a novel strategy for the treatment of ischemic heart disease.
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Affiliation(s)
- Boyd R Rorabaugh
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio (B.R.R., N.W.M., S.L.S., A.D.B.); Department of Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, Iowa (B.C., J.Y., R.A.F.); and Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (S.W.W., R.R.N.)
| | - Bandana Chakravarti
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio (B.R.R., N.W.M., S.L.S., A.D.B.); Department of Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, Iowa (B.C., J.Y., R.A.F.); and Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (S.W.W., R.R.N.)
| | - Nathaniel W Mabe
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio (B.R.R., N.W.M., S.L.S., A.D.B.); Department of Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, Iowa (B.C., J.Y., R.A.F.); and Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (S.W.W., R.R.N.)
| | - Sarah L Seeley
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio (B.R.R., N.W.M., S.L.S., A.D.B.); Department of Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, Iowa (B.C., J.Y., R.A.F.); and Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (S.W.W., R.R.N.)
| | - Albert D Bui
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio (B.R.R., N.W.M., S.L.S., A.D.B.); Department of Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, Iowa (B.C., J.Y., R.A.F.); and Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (S.W.W., R.R.N.)
| | - Jianqi Yang
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio (B.R.R., N.W.M., S.L.S., A.D.B.); Department of Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, Iowa (B.C., J.Y., R.A.F.); and Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (S.W.W., R.R.N.)
| | - Stephanie W Watts
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio (B.R.R., N.W.M., S.L.S., A.D.B.); Department of Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, Iowa (B.C., J.Y., R.A.F.); and Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (S.W.W., R.R.N.)
| | - Richard R Neubig
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio (B.R.R., N.W.M., S.L.S., A.D.B.); Department of Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, Iowa (B.C., J.Y., R.A.F.); and Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (S.W.W., R.R.N.)
| | - Rory A Fisher
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio (B.R.R., N.W.M., S.L.S., A.D.B.); Department of Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, Iowa (B.C., J.Y., R.A.F.); and Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (S.W.W., R.R.N.)
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Neubig RR. RGS-Insensitive G Proteins as In Vivo Probes of RGS Function. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 133:13-30. [PMID: 26123300 DOI: 10.1016/bs.pmbts.2015.04.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Guanine nucleotide-binding proteins of the inhibitory (Gi/o) class play critical physiological roles and the receptors that activate them are important therapeutic targets (e.g., mu opioid, serotonin 5HT1a, etc.). Gi/o proteins are negatively regulated by regulator of G protein signaling (RGS) proteins. The redundant actions of the 20 different RGS family members have made it difficult to establish their overall physiological role. A unique G protein mutation (G184S in Gαi/o) prevents RGS binding to the Gα subunit and blocks all RGS action at that particular Gα subunit. The robust phenotypes of mice expressing these RGS-insensitive (RGSi) mutant G proteins illustrate the profound action of RGS proteins in cardiovascular, metabolic, and central nervous system functions. Specifically, the enhanced Gαi2 signaling through the RGSi Gαi2(G184S) mutant knock-in mice shows protection against cardiac ischemia/reperfusion injury and potentiation of serotonin-mediated antidepressant actions. In contrast, the RGSi Gαo mutant knock-in produces enhanced mu-opioid receptor-mediated analgesia but also a seizure phenotype. These genetic models provide novel insights into potential therapeutic strategies related to RGS protein inhibitors and/or G protein subtype-biased agonists at particular GPCRs.
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Affiliation(s)
- Richard R Neubig
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan, USA.
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Stewart A, Fisher RA. Introduction: G Protein-coupled Receptors and RGS Proteins. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 133:1-11. [PMID: 26123299 DOI: 10.1016/bs.pmbts.2015.03.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Here, we provide an overview of the role of regulator of G protein-signaling (RGS) proteins in signaling by G protein-coupled receptors (GPCRs), the latter of which represent the largest class of cell surface receptors in humans responsible for transducing diverse extracellular signals into the intracellular environment. Given that GPCRs regulate virtually every known physiological process, it is unsurprising that their dysregulation plays a causative role in many human diseases and they are targets of 40-50% of currently marketed pharmaceuticals. Activated GPCRs function as GTPase exchange factors for Gα subunits of heterotrimeric G proteins, promoting the formation of Gα-GTP and dissociated Gβγ subunits that regulate diverse effectors including enzymes, ion channels, and protein kinases. Termination of signaling is mediated by the intrinsic GTPase activity of Gα subunits leading to reformation of the inactive Gαβγ heterotrimer. RGS proteins determine the magnitude and duration of cellular responses initiated by many GPCRs by functioning as GTPase-accelerating proteins (GAPs) for specific Gα subunits. Twenty canonical mammalian RGS proteins, divided into four subfamilies, act as functional GAPs while almost 20 additional proteins contain nonfunctional RGS homology domains that often mediate interaction with GPCRs or Gα subunits. RGS protein biochemistry has been well elucidated in vitro, but the physiological functions of each RGS family member remain largely unexplored. This book summarizes recent advances employing modified model organisms that reveal RGS protein functions in vivo, providing evidence that RGS protein modulation of G protein signaling and GPCRs can be as important as initiation of signaling by GPCRs.
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Affiliation(s)
- Adele Stewart
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Rory A Fisher
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA.
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Rorabaugh BR, Krivenko A, Eisenmann ED, Bui AD, Seeley S, Fry ME, Lawson JD, Stoner LE, Johnson BL, Zoladz PR. Sex-dependent effects of chronic psychosocial stress on myocardial sensitivity to ischemic injury. Stress 2015; 18:645-53. [PMID: 26458179 DOI: 10.3109/10253890.2015.1087505] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Individuals with post-traumatic stress disorder (PTSD) experience many debilitating symptoms, including intrusive memories, persistent anxiety and avoidance of trauma-related cues. PTSD also results in numerous physiological complications, including increased risk for cardiovascular disease (CVD). However, characterization of PTSD-induced cardiovascular alterations is lacking, especially in preclinical models of the disorder. Thus, we examined the impact of a psychosocial predator-based animal model of PTSD on myocardial sensitivity to ischemic injury. Male and female Sprague-Dawley rats were exposed to psychosocial stress or control conditions for 31 days. Stressed rats were given two cat exposures, separated by a period of 10 days, and were subjected to daily social instability throughout the paradigm. Control rats were handled daily for the duration of the experiment. Rats were tested on the elevated plus maze (EPM) on day 32, and hearts were isolated on day 33 and subjected to 20 min ischemia and 2 h reperfusion on a Langendorff isolated heart system. Stressed male and female rats gained less body weight relative to controls, but only stressed males exhibited increased anxiety on the EPM. Male, but not female, rats exposed to psychosocial stress exhibited significantly larger infarcts and attenuated post-ischemic recovery of contractile function compared to controls. Our data demonstrate that predator stress combined with daily social instability sex-dependently increases myocardial sensitivity to ischemic injury. Thus, this manipulation may be useful for studying potential mechanisms underlying cardiovascular alterations in PTSD, as well as sex differences in the cardiovascular stress response.
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Affiliation(s)
| | - Anna Krivenko
- b Department of Psychology , Sociology & Criminal Justice, Ohio Northern University , Ada , OH , USA
| | - Eric D Eisenmann
- b Department of Psychology , Sociology & Criminal Justice, Ohio Northern University , Ada , OH , USA
| | - Albert D Bui
- a Department of Pharmaceutical & Biomedical Sciences and
| | - Sarah Seeley
- a Department of Pharmaceutical & Biomedical Sciences and
| | - Megan E Fry
- b Department of Psychology , Sociology & Criminal Justice, Ohio Northern University , Ada , OH , USA
| | - Joseph D Lawson
- b Department of Psychology , Sociology & Criminal Justice, Ohio Northern University , Ada , OH , USA
| | - Lauren E Stoner
- b Department of Psychology , Sociology & Criminal Justice, Ohio Northern University , Ada , OH , USA
| | - Brandon L Johnson
- b Department of Psychology , Sociology & Criminal Justice, Ohio Northern University , Ada , OH , USA
| | - Phillip R Zoladz
- b Department of Psychology , Sociology & Criminal Justice, Ohio Northern University , Ada , OH , USA
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Ganss R. Keeping the Balance Right. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 133:93-121. [DOI: 10.1016/bs.pmbts.2015.02.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Melsom CB, Ørstavik Ø, Osnes JB, Skomedal T, Levy FO, Krobert KA. Gi proteins regulate adenylyl cyclase activity independent of receptor activation. PLoS One 2014; 9:e106608. [PMID: 25203113 PMCID: PMC4159282 DOI: 10.1371/journal.pone.0106608] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 07/30/2014] [Indexed: 11/19/2022] Open
Abstract
Background and purpose Despite the view that only β2- as opposed to β1-adrenoceptors (βARs) couple to Gi, some data indicate that the β1AR-evoked inotropic response is also influenced by the inhibition of Gi. Therefore, we wanted to determine if Gi exerts tonic receptor-independent inhibition upon basal adenylyl cyclase (AC) activity in cardiomyocytes. Experimental approach We used the Gs-selective (R,R)- and the Gs- and Gi-activating (R,S)-fenoterol to selectively activate β2ARs (β1AR blockade present) in combination with Gi inactivation with pertussis toxin (PTX). We also determined the effect of PTX upon basal and forskolin-mediated responses. Contractility was measured ex vivo in left ventricular strips and cAMP accumulation was measured in isolated ventricular cardiomyocytes from adult Wistar rats. Key results PTX amplified both the (R,R)- and (R,S)-fenoterol-evoked maximal inotropic response and concentration-dependent increases in cAMP accumulation. The EC50 values of fenoterol matched published binding affinities. The PTX enhancement of the Gs-selective (R,R)-fenoterol-mediated responses suggests that Gi regulates AC activity independent of receptor coupling to Gi protein. Consistent with this hypothesis, forskolin-evoked cAMP accumulation was increased and inotropic responses to forskolin were potentiated by PTX treatment. In non-PTX-treated tissue, phosphodiesterase (PDE) 3 and 4 inhibition or removal of either constitutive muscarinic receptor activation of Gi with atropine or removal of constitutive adenosine receptor activation with CGS 15943 had no effect upon contractility. However, in PTX-treated tissue, PDE3 and 4 inhibition alone increased basal levels of cAMP and accordingly evoked a large inotropic response. Conclusions and implications Together, these data indicate that Gi exerts intrinsic receptor-independent inhibitory activity upon AC. We propose that PTX treatment shifts the balance of intrinsic Gi and Gs activity upon AC towards Gs, enhancing the effect of all cAMP-mediated inotropic agents.
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Affiliation(s)
- Caroline Bull Melsom
- Department of Pharmacology, Faculty of Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway
- K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Øivind Ørstavik
- Department of Pharmacology, Faculty of Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway
- K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Jan-Bjørn Osnes
- Department of Pharmacology, Faculty of Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway
- K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Tor Skomedal
- Department of Pharmacology, Faculty of Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway
- K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Finn Olav Levy
- Department of Pharmacology, Faculty of Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway
- K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, Faculty of Medicine, University of Oslo, Oslo, Norway
- * E-mail:
| | - Kurt Allen Krobert
- Department of Pharmacology, Faculty of Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway
- K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, Faculty of Medicine, University of Oslo, Oslo, Norway
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11
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Parra S, Huang X, Charbeneau RA, Wade SM, Kaur K, Rorabaugh BR, Neubig RR. Conditional disruption of interactions between Gαi2 and regulator of G protein signaling (RGS) proteins protects the heart from ischemic injury. BMC Pharmacol Toxicol 2014; 15:29. [PMID: 24899231 PMCID: PMC4059092 DOI: 10.1186/2050-6511-15-29] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 05/28/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Regulator of G protein signaling (RGS) proteins suppress G protein coupled receptor signaling by catalyzing the hydrolysis of Gα-bound guanine nucleotide triphosphate. Transgenic mice in which RGS-mediated regulation of Gαi2 is lost (RGS insensitive Gαi2G184S) exhibit beneficial (protection against ischemic injury) and detrimental (enhanced fibrosis) cardiac phenotypes. This mouse model has revealed the physiological significance of RGS/Gαi2 interactions. Previous studies of the Gαi2G184S mutation used mice that express this mutant protein throughout their lives. Thus, it is unclear whether these phenotypes result from chronic or acute Gαi2G184S expression. We addressed this issue by developing mice that conditionally express Gαi2G184S. METHODS Mice that conditionally express RGS insensitive Gαi2G184S were generated using a floxed minigene strategy. Conditional expression of Gαi2G184S was characterized by reverse transcription polymerase chain reaction and by enhancement of agonist-induced inhibition of cAMP production in isolated cardiac fibroblasts. The impact of conditional RGS insensitive Gαi2G184S expression on ischemic injury was assessed by measuring contractile recovery and infarct sizes in isolated hearts subjected to 30 min ischemia and 2 hours reperfusion. RESULTS We demonstrate tamoxifen-dependent expression of Gαi2G184S, enhanced inhibition of cAMP production, and cardioprotection from ischemic injury in hearts conditionally expressing Gαi2G184S. Thus the cardioprotective phenotype previously reported in mice expressing Gαi2G184S does not require embryonic or chronic Gαi2G184S expression. Rather, cardioprotection occurs following acute (days rather than months) expression of Gαi2G184S. CONCLUSIONS These data suggest that RGS proteins might provide new therapeutic targets to protect the heart from ischemic injury. We anticipate that this model will be valuable for understanding the time course (chronic versus acute) and mechanisms of other phenotypic changes that occur following disruption of interactions between Gαi2 and RGS proteins.
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Affiliation(s)
| | | | | | | | | | - Boyd R Rorabaugh
- Department of Pharmaceutical and Biomedical Sciences, Ohio Northern University College of Pharmacy, Ada, OH 45810, USA.
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12
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Köhler D, Devanathan V, Bernardo de Oliveira Franz C, Eldh T, Novakovic A, Roth JM, Granja T, Birnbaumer L, Rosenberger P, Beer-Hammer S, Nürnberg B. Gαi2- and Gαi3-deficient mice display opposite severity of myocardial ischemia reperfusion injury. PLoS One 2014; 9:e98325. [PMID: 24858945 PMCID: PMC4032280 DOI: 10.1371/journal.pone.0098325] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 04/30/2014] [Indexed: 12/19/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) are the most abundant receptors in the heart and therefore are common targets for cardiovascular therapeutics. The activated GPCRs transduce their signals via heterotrimeric G-proteins. The four major families of G-proteins identified so far are specified through their α-subunit: Gαi, Gαs, Gαq and G12/13. Gαi-proteins have been reported to protect hearts from ischemia reperfusion injury. However, determining the individual impact of Gαi2 or Gαi3 on myocardial ischemia injury has not been clarified yet. Here, we first investigated expression of Gαi2 and Gαi3 on transcriptional level by quantitative PCR and on protein level by immunoblot analysis as well as by immunofluorescence in cardiac tissues of wild-type, Gαi2-, and Gαi3-deficient mice. Gαi2 was expressed at higher levels than Gαi3 in murine hearts, and irrespective of the isoform being knocked out we observed an up regulation of the remaining Gαi-protein. Myocardial ischemia promptly regulated cardiac mRNA and with a slight delay protein levels of both Gαi2 and Gαi3, indicating important roles for both Gαi isoforms. Furthermore, ischemia reperfusion injury in Gαi2- and Gαi3-deficient mice exhibited opposite outcomes. Whereas the absence of Gαi2 significantly increased the infarct size in the heart, the absence of Gαi3 or the concomitant upregulation of Gαi2 dramatically reduced cardiac infarction. In conclusion, we demonstrate for the first time that the genetic ablation of Gαi proteins has protective or deleterious effects on cardiac ischemia reperfusion injury depending on the isoform being absent.
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Affiliation(s)
- David Köhler
- Department of Anesthesiology and Intensive Care Medicine, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
| | - Vasudharani Devanathan
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
| | - Claudia Bernardo de Oliveira Franz
- Department of Anesthesiology and Intensive Care Medicine, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
| | - Therese Eldh
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
| | - Ana Novakovic
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
| | - Judith M. Roth
- Department of Anesthesiology and Intensive Care Medicine, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
| | - Tiago Granja
- Department of Anesthesiology and Intensive Care Medicine, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
| | - Lutz Birnbaumer
- Laboratory of Neurobiology, Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, United States of America
| | - Peter Rosenberger
- Department of Anesthesiology and Intensive Care Medicine, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
| | - Sandra Beer-Hammer
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
- * E-mail: (SBH); (BN)
| | - Bernd Nürnberg
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
- * E-mail: (SBH); (BN)
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13
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Stewart A, Huang J, Fisher RA. RGS Proteins in Heart: Brakes on the Vagus. Front Physiol 2012; 3:95. [PMID: 22685433 PMCID: PMC3368389 DOI: 10.3389/fphys.2012.00095] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 03/27/2012] [Indexed: 12/14/2022] Open
Abstract
It has been nearly a century since Otto Loewi discovered that acetylcholine (ACh) release from the vagus produces bradycardia and reduced cardiac contractility. It is now known that parasympathetic control of the heart is mediated by ACh stimulation of G(i/o)-coupled muscarinic M2 receptors, which directly activate G protein-coupled inwardly rectifying potassium (GIRK) channels via Gβγ resulting in membrane hyperpolarization and inhibition of action potential (AP) firing. However, expression of M2R-GIRK signaling components in heterologous systems failed to recapitulate native channel gating kinetics. The missing link was identified with the discovery of regulator of G protein signaling (RGS) proteins, which act as GTPase-activating proteins to accelerate the intrinsic GTPase activity of Gα resulting in termination of Gα- and Gβγ-mediated signaling to downstream effectors. Studies in mice expressing an RGS-insensitive Gα(i2) mutant (G184S) implicated endogenous RGS proteins as key regulators of parasympathetic signaling in heart. Recently, two RGS proteins have been identified as critical regulators of M2R signaling in heart. RGS6 exhibits a uniquely robust expression in heart, especially in sinoatrial (SAN) and atrioventricular nodal regions. Mice lacking RGS6 exhibit increased bradycardia and inhibition of SAN AP firing in response to CCh as well as a loss of rapid activation and deactivation kinetics and current desensitization for ACh-induced GIRK current (I(KACh)). Similar findings were observed in mice lacking RGS4. Thus, dysregulation in RGS protein expression or function may contribute to pathologies involving aberrant electrical activity in cardiac pacemaker cells. Moreover, RGS6 expression was found to be up-regulated in heart under certain pathological conditions, including doxorubicin treatment, which is known to cause life-threatening cardiotoxicity and atrial fibrillation in cancer patients. On the other hand, increased vagal tone may be cardioprotective in heart failure where acetylcholinesterase inhibitors and vagal stimulation have been proposed as potential therapeutics. Together, these studies identify RGS proteins, especially RGS6, as new therapeutic targets for diseases such as sick sinus syndrome or other maladies involving abnormal autonomic control of the heart.
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Affiliation(s)
- Adele Stewart
- Department of Pharmacology, Carver College of Medicine, University of Iowa Iowa City, IA, USA
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Gαi2 signaling: friend or foe in cardiac injury and heart failure? Naunyn Schmiedebergs Arch Pharmacol 2012; 385:443-53. [PMID: 22411356 DOI: 10.1007/s00210-011-0705-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 10/13/2011] [Indexed: 12/20/2022]
Abstract
Receptors coupled to G proteins have many effects on the heart. Enhanced signaling by Gα(s) and Gα(q) leads to cardiac injury and heart failure, while Gα(i2) signaling in cardiac myocytes can protect against ischemic injury and β-adrenergic-induced heart failure. We asked whether enhanced Gα(i2) signaling in mice could protect against heart failure using a point mutation in Gα(i2) (G184S), which prevents negative regulation by regulators of G protein signaling. Contrary to our expectation, it worsened effects of a genetic dilated cardiomyopathy (DCM) and catecholamine-induced cardiac injury. Gα (i2) (G184S/+) /DCM double heterozygote mice (TG9(+)Gα (i2) (G184S/+)) had substantially decreased survival compared to DCM animals. Furthermore, heart weight/body weight ratios (HW/BW) were significantly greater in TG9(+)Gα (i2) (G184S/+) mice as was expression of natriuretic peptide genes. Catecholamine injury in Gα (i2) (G184S/G184S) mutant mice produced markedly increased isoproterenol-induced fibrosis and collagen III gene expression vs WT mice. Cardiac fibroblasts from Gα (i2) (G184S/G184S) mice also showed a serum-dependent increase in proliferation and ERK phosphorylation, which were blocked by pertussis toxin and a mitogen-activated protein/extracellular signal-regulated kinase kinase inhibitor. Gα(i2) signaling in cardiac myocytes protects against ischemic injury but enhancing Gα(i2) signaling overall may have detrimental effects in heart failure, perhaps through actions on cardiac fibroblasts.
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Abstract
Signal transduction through G-protein-coupled receptors (GPCRs) is central for the regulation of virtually all cellular functions and has been widely implicated in human disease. Regulators of G-protein signaling (RGS proteins) belong to a diverse protein family that was originally discovered for their ability to accelerate signal termination in response to GPCR stimulation, thereby reducing the amplitude and duration of GPCR effects. All RGS proteins share a common RGS domain that interacts with G protein α subunits and mediates their biological regulation of GPCR signaling. However, RGS proteins differ widely in size and the organization of their sequences flanking the RGS domain, which contain several additional functional domains that facilitate protein-protein (or protein-lipid) interactions. RGS proteins are subject to posttranslational modifications, and, in addition, their expression, activity, and subcellular localization can be dynamically regulated. Thus, there exists a wide array of mechanisms that facilitate their proper function as modulators and integrators of G-protein signaling. Several RGS proteins have been implicated in the cardiac remodeling response and heart rate regulation, and changes in RGS protein expression and/or function are believed to participate in the pathophysiology of cardiac hypertrophy, failure and arrhythmias as well as hypertension. This review is based on recent advances in our understanding of the expression pattern, regulation, and functional role of canonical RGS proteins, with a special focus on the healthy heart and the diseased heart. In addition, we discuss their potential and promise as therapeutic targets as well as strategies to modulate their expression and function.
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Affiliation(s)
- Peng Zhang
- Cardiovascular Research Center, Rhode Island Hospital and Alpert Medical School of Brown University, 1 Hoppin St, Providence, RI 02903, USA
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Korthuis RJ. Filling GAPs in the understanding of cardioprotection induced by GPCR activation: RGS proteins modulate ischaemic injury. Cardiovasc Res 2011; 91:5-6. [PMID: 21613276 DOI: 10.1093/cvr/cvr141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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