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McNeill SM, Zhao P. The roles of RGS proteins in cardiometabolic disease. Br J Pharmacol 2024; 181:2319-2337. [PMID: 36964984 DOI: 10.1111/bph.16076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 02/12/2023] [Accepted: 03/20/2023] [Indexed: 03/27/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are the most prominent receptors on the surface of the cell and play a central role in the regulation of cardiac and metabolic functions. GPCRs transmit extracellular stimuli to the interior of the cells by activating one or more heterotrimeric G proteins. The duration and intensity of G protein-mediated signalling are tightly controlled by a large array of intracellular mediators, including the regulator of G protein signalling (RGS) proteins. RGS proteins selectively promote the GTPase activity of a subset of Gα subunits, thus serving as negative regulators in a pathway-dependent manner. In the current review, we summarise the involvement of RGS proteins in cardiometabolic function with a focus on their tissue distribution, mechanisms of action and dysregulation under various disease conditions. We also discuss the potential therapeutic applications for targeting RGS proteins in treating cardiometabolic conditions and current progress in developing RGS modulators. LINKED ARTICLES: This article is part of a themed issue Therapeutic Targeting of G Protein-Coupled Receptors: hot topics from the Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists 2021 Virtual Annual Scientific Meeting. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.14/issuetoc.
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Affiliation(s)
- Samantha M McNeill
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Peishen Zhao
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Cryo-Electron Microscopy of Membrane Proteins (CCeMMP), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
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Kaur G, Verma SK, Singh D, Singh NK. Role of G-Proteins and GPCRs in Cardiovascular Pathologies. Bioengineering (Basel) 2023; 10:bioengineering10010076. [PMID: 36671648 PMCID: PMC9854459 DOI: 10.3390/bioengineering10010076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 12/19/2022] [Accepted: 01/03/2023] [Indexed: 01/09/2023] Open
Abstract
Cell signaling is a fundamental process that enables cells to survive under various ecological and environmental contexts and imparts tolerance towards stressful conditions. The basic machinery for cell signaling includes a receptor molecule that senses and receives the signal. The primary form of the signal might be a hormone, light, an antigen, an odorant, a neurotransmitter, etc. Similarly, heterotrimeric G-proteins principally provide communication from the plasma membrane G-protein-coupled receptors (GPCRs) to the inner compartments of the cells to control various biochemical activities. G-protein-coupled signaling regulates different physiological functions in the targeted cell types. This review article discusses G-proteins' signaling and regulation functions and their physiological relevance. In addition, we also elaborate on the role of G-proteins in several cardiovascular diseases, such as myocardial ischemia, hypertension, atherosclerosis, restenosis, stroke, and peripheral artery disease.
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Affiliation(s)
- Geetika Kaur
- Integrative Biosciences Center, Wayne State University, Detroit, MI 48202, USA
- Department of Ophthalmology, Visual and Anatomical Sciences, School of Medicine, Wayne State University, Detroit, MI 48202, USA
| | - Shailendra Kumar Verma
- Integrative Biosciences Center, Wayne State University, Detroit, MI 48202, USA
- Department of Ophthalmology, Visual and Anatomical Sciences, School of Medicine, Wayne State University, Detroit, MI 48202, USA
| | - Deepak Singh
- Lloyd Institute of Engineering and Technology, Greater Noida 201306, India
| | - Nikhlesh K. Singh
- Integrative Biosciences Center, Wayne State University, Detroit, MI 48202, USA
- Department of Ophthalmology, Visual and Anatomical Sciences, School of Medicine, Wayne State University, Detroit, MI 48202, USA
- Correspondence:
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3
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Wu X, Gou H, Zhou O, Qiu H, Liu H, Fu Z, Chen L. Human umbilical cord mesenchymal stem cells combined with pirfenidone upregulates the expression of RGS2 in the pulmonary fibrosis in mice. Respir Res 2022; 23:270. [PMID: 36182915 PMCID: PMC9526322 DOI: 10.1186/s12931-022-02192-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 09/22/2022] [Indexed: 11/10/2022] Open
Abstract
Objective The therapeutic effect of umbilical cord-derived mesenchymal stem cells (hUC-MSCs) in combination with pirfenidone (PFD) on pulmonary fibrosis in mice and its possible mechanism were investigated. Methods C57BL/6 mice were randomly divided into six groups: control group, model group, P10 group, P30 group, P100 group, and P300 group. Modeled by tracheal intubation with 3 mg/kg bleomycin drip, each dose of PFD was administered daily by gavage from day 7 onwards. The mice were observed continuously for 21 days and survival was recorded. Lung tissues were collected on day 21, and hematoxylin–eosin (HE) and Masson staining were performed to assess morphological changes and collagen deposition in the lungs. Collagen content was measured by the Sircol method, and fibrosis marker levels were detected by PCR and Western blot. Another batch of C57BL/6 mice was then randomly divided into five groups: hUC-MSC control group, model group, P100 group, hUC-MSC treatment group, and hUC-MSCs + P30 group. On day 7, 5 × 105 hUC-MSCs were injected into the tail vein, the mice were administered PFD gavage daily from day 7 onwards, and their survival was recorded. Lung tissues were collected on day 21 to detect pathological changes, the collagen content, and the expression of regulator of G protein signaling 2 (RGS2). Pulmonary myofibroblasts (MFBs) were divided into an MFB group and an MFB + hUC-MSCs group; different doses of PFD were administered to each group, and the levels of RGS2, intracellular Ca2+, and fibrosis markers were recorded for each group. Results Compared with other PFD group doses, the P100 group had significantly improved mouse survival and lung pathology and significantly reduced collagen and fibrosis marker levels (p < 0.05). The hUC-MSCs + P30 group had significantly improved mouse survival and lung pathology, significantly reduced collagen content and fibrosis marker levels (p < 0.05), and the efficacy was better than that of the P100 and hUC-MSCs groups (p < 0.05). RGS2 expression was significantly higher in the MSCs + P30 group compared with the P100 and hUC-MSCs groups (p < 0.05). PFD increased RGS2 expression in MFBs (p < 0.05) in a dose-dependent manner. Compared with PFD and hUC-MSCs treatment alone, combination of hUC-MSCs and PFD increased RGS2 protein levels, significantly decreased intracellular Ca2+ concentration, and significantly reduced fibrosis markers. Conclusion The findings suggest that hUC-MSCs combined with low-dose PFD have a therapeutic effect better than that of the two treatments used separately. Its effect on attenuating bleomycin-induced pulmonary fibrosis in mice is related to the increase of RGS2. Supplementary Information The online version contains supplementary material available at 10.1186/s12931-022-02192-6.
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Affiliation(s)
- Xian Wu
- Division of Pediatric Pulmonology and Immunology, West China Second University Hospital, Sichuan University, Chengdu, 610041, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, 610041, Sichuan, China.,NHC Key Laboratory of Chronobiology, Sichuan University, Chengdu, 610065, Sichuan, China
| | - Hao Gou
- Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, Sichuan, China
| | - Ou Zhou
- Pediatric Research Institute, Ministry of Education Key Laboratory of Child Development and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, 400015, China
| | - Huijun Qiu
- Pediatric Research Institute, Ministry of Education Key Laboratory of Child Development and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, 400015, China
| | - Hanmin Liu
- Division of Pediatric Pulmonology and Immunology, West China Second University Hospital, Sichuan University, Chengdu, 610041, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, 610041, Sichuan, China.,NHC Key Laboratory of Chronobiology, Sichuan University, Chengdu, 610065, Sichuan, China
| | - Zhou Fu
- Pediatric Research Institute, Ministry of Education Key Laboratory of Child Development and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, 400015, China. .,Department of Respiratory Medicine, Children's Hospital of Chongqing Medical University, Chongqing, 400015, China. .,Chongqing Engineering Research Center of Stem Cell Therapy, Chongqing, 400015, China.
| | - Lina Chen
- Division of Pediatric Pulmonology and Immunology, West China Second University Hospital, Sichuan University, Chengdu, 610041, Sichuan, China. .,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, 610041, Sichuan, China. .,NHC Key Laboratory of Chronobiology, Sichuan University, Chengdu, 610065, Sichuan, China.
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Lymperopoulos A, Suster MS, Borges JI. Cardiovascular GPCR regulation by regulator of G protein signaling proteins. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2022; 193:145-166. [PMID: 36357075 DOI: 10.1016/bs.pmbts.2022.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
G protein-coupled receptors (GPCRs) play pivotal roles in regulation of cardiovascular homeostasis across all vertebrate species, including humans. In terms of normal cellular function, termination of GPCR signaling via the heterotrimeric G proteins is equally (if not more) important to its stimulation. The Regulator of G protein Signaling (RGS) protein superfamily are indispensable for GPCR signaling cessation at the cell membrane, and thus, for cellular control of GPCR signaling and function. Perturbations in both activation and termination of G protein signaling underlie many examples of cardiovascular dysfunction and heart disease pathogenesis. Despite the plethora of over 30 members comprising the mammalian RGS protein superfamily, each member interacts with a specific set of second messenger pathways and GPCR types/subtypes in a tissue/cell type-specific manner. An increasing number of studies over the past two decades have provided compelling evidence for the involvement of various RGS proteins in physiological regulation of cardiovascular GPCRs and, consequently, also in the pathophysiology of several cardiovascular ailments. This chapter summarizes the current understanding of the functional roles of RGS proteins as they pertain to cardiovascular, i.e., heart, blood vessel, and platelet GPCR function, with a particular focus on their implications for chronic heart failure pathophysiology and therapy.
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Affiliation(s)
- Anastasios Lymperopoulos
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences, Nova Southeastern University College of Pharmacy, Fort Lauderdale, FL, United States.
| | - Malka S Suster
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences, Nova Southeastern University College of Pharmacy, Fort Lauderdale, FL, United States
| | - Jordana I Borges
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences, Nova Southeastern University College of Pharmacy, Fort Lauderdale, FL, United States
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Jang EJ, Kim YJ, Hwang HS, Yee J, Gwak HS. Associations of GNAS and RGS Gene Polymorphisms with the Risk of Ritodrine-Induced Adverse Events in Korean Women with Preterm Labor: A Cohort Study. Pharmaceutics 2022; 14:pharmaceutics14061220. [PMID: 35745791 PMCID: PMC9227008 DOI: 10.3390/pharmaceutics14061220] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/02/2022] [Accepted: 06/07/2022] [Indexed: 02/04/2023] Open
Abstract
Ritodrine, a β2-adrenergic receptor agonist, is among most commonly prescribed tocolytic agents. This study aimed to evaluate the associations of single nucleotide polymorphisms in GNAS, RGS2, and RGS5 with the risk of ritodrine-induced adverse events (AEs) and develop a risk scoring system to identify high-risk patients. This is the prospective cohort study conducted at the Ewha Woman’s University Mokdong Hospital between January 2010 and October 2016. Pregnant women were included if they were treated with ritodrine for preterm labor with regular uterine contractions (at least 3 every 10 min) and cervical dilation. A total of 6, 3, and 5 single nucleotide polymorphisms (SNPs) of GNAS, RGS2, and RGS5 genes were genotyped and compared in patients with and without ritodrine-induced AEs. A total of 163 patients were included in this study. After adjusting confounders, GNAS rs3730168 (per-allele odds ratio (OR): 2.1; 95% confidence interval (95% CI): 1.0–4.3) and RGS2 rs1152746 (per-allele OR: 2.6, 95% CI: 1.1–6.5) were significantly associated with ritodrine-induced AEs. According to the constructed risk scoring models, patients with 0, 1, 2, 3, 4, and 5 points showed 0%, 13%, 19%, 31%, 46%, and 100% risks of AEs. This study suggested that GNAS and RGS2 polymorphisms could affect the risk of AEs in patients treated with ritodrine.
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Affiliation(s)
- Eun-Jeong Jang
- College of Pharmacy and Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Korea;
| | - Young-Ju Kim
- Department of Obstetrics and Gynecology, Ewha Womans University School of Medicine, Seoul 07985, Korea;
| | - Han-Sung Hwang
- Department of Obstetrics and Gynecology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul 05030, Korea;
| | - Jeong Yee
- College of Pharmacy and Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Korea;
- Correspondence: (J.Y.); (H.-S.G.); Tel.: +82-2-3277-3052 (J.Y.); +82-2-3277-4376 (H.-S.G.); Fax: +82-2-3277-3051 (J.Y. & H.-S.G.)
| | - Hye-Sun Gwak
- College of Pharmacy and Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Korea;
- Correspondence: (J.Y.); (H.-S.G.); Tel.: +82-2-3277-3052 (J.Y.); +82-2-3277-4376 (H.-S.G.); Fax: +82-2-3277-3051 (J.Y. & H.-S.G.)
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Cardioprotective effects of early intervention with sacubitril/valsartan on pressure overloaded rat hearts. Sci Rep 2021; 11:16542. [PMID: 34400686 PMCID: PMC8368201 DOI: 10.1038/s41598-021-95988-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 08/03/2021] [Indexed: 12/11/2022] Open
Abstract
Left ventricular remodeling due to pressure overload is associated with poor prognosis. Sacubitril/valsartan is the first-in-class Angiotensin Receptor Neprilysin Inhibitor and has been demonstrated to have superior beneficial effects in the settings of heart failure. The aim of this study was to determine whether sacubitril/valsartan has cardioprotective effect in the early intervention of pressure overloaded hearts and whether it is superior to valsartan alone. We induced persistent left ventricular pressure overload in rats by ascending aortic constriction surgery and orally administrated sacubitril/valsartan, valsartan, or vehicle one week post operation for 10 weeks. We also determined the effects of sacubitril/valsartan over valsartan on adult ventricular myocytes and fibroblasts that were isolated from healthy rats and treated in culture. We found that early intervention with sacubitril/valsartan is superior to valsartan in reducing pressure overload-induced ventricular fibrosis and in reducing angiotensin II-induced adult ventricular fibroblast activation. While neither sacubitril/valsartan nor valsartan changes cardiac hypertrophy development, early intervention with sacubitril/valsartan protects ventricular myocytes from mitochondrial dysfunction and is superior to valsartan in reducing mitochondrial oxidative stress in response to persistent left ventricular pressure overload. In conclusion, our findings demonstrate that sacubitril/valsartan has a superior cardioprotective effect over valsartan in the early intervention of pressure overloaded hearts, which is independent of the reduction of left ventricular afterload. Our study provides evidence in support of potential benefits of the use of sacubitril/valsartan in patients with resistant hypertension or in patients with severe aortic stenosis.
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Mishra S, Kass DA. Cellular and molecular pathobiology of heart failure with preserved ejection fraction. Nat Rev Cardiol 2021; 18:400-423. [PMID: 33432192 PMCID: PMC8574228 DOI: 10.1038/s41569-020-00480-6] [Citation(s) in RCA: 183] [Impact Index Per Article: 61.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/16/2020] [Indexed: 01/30/2023]
Abstract
Heart failure with preserved ejection fraction (HFpEF) affects half of all patients with heart failure worldwide, is increasing in prevalence, confers substantial morbidity and mortality, and has very few effective treatments. HFpEF is arguably the greatest unmet medical need in cardiovascular disease. Although HFpEF was initially considered to be a haemodynamic disorder characterized by hypertension, cardiac hypertrophy and diastolic dysfunction, the pandemics of obesity and diabetes mellitus have modified the HFpEF syndrome, which is now recognized to be a multisystem disorder involving the heart, lungs, kidneys, skeletal muscle, adipose tissue, vascular system, and immune and inflammatory signalling. This multiorgan involvement makes HFpEF difficult to model in experimental animals because the condition is not simply cardiac hypertrophy and hypertension with abnormal myocardial relaxation. However, new animal models involving both haemodynamic and metabolic disease, and increasing efforts to examine human pathophysiology, are revealing new signalling pathways and potential therapeutic targets. In this Review, we discuss the cellular and molecular pathobiology of HFpEF, with the major focus being on mechanisms relevant to the heart, because most research has focused on this organ. We also highlight the involvement of other important organ systems, including the lungs, kidneys and skeletal muscle, efforts to characterize patients with the use of systemic biomarkers, and ongoing therapeutic efforts. Our objective is to provide a roadmap of the signalling pathways and mechanisms of HFpEF that are being characterized and which might lead to more patient-specific therapies and improved clinical outcomes.
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Affiliation(s)
- Sumita Mishra
- Department of Medicine, Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David A. Kass
- Department of Medicine, Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.,
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McNabb HJ, Zhang Q, Sjögren B. Emerging Roles for Regulator of G Protein Signaling 2 in (Patho)physiology. Mol Pharmacol 2020; 98:751-760. [PMID: 32973086 DOI: 10.1124/molpharm.120.000111] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 09/08/2020] [Indexed: 12/11/2022] Open
Abstract
Since their discovery in the mid-1990s, regulator of G protein signaling (RGS) proteins have emerged as key regulators of signaling through G protein-coupled receptors. Among the over 20 known RGS proteins, RGS2 has received increasing interest as a potential therapeutic drug target with broad clinical implications. RGS2 is a member of the R4 subfamily of RGS proteins and is unique in that it is selective for Gα q Despite only having an RGS domain, responsible for the canonical GTPase activating protein activity, RGS2 can regulate additional processes, such as protein synthesis and adenylate cyclase activity, through protein-protein interactions. Here we provide an update of the current knowledge of RGS2 function as it relates to molecular mechanisms of regulation as well as its potential role in regulating a number of physiologic systems and pathologies, including cardiovascular disease and central nervous system disorders, as well as various forms of cancer. SIGNIFICANCE STATEMENT: Regulator of G protein signaling (RGS) proteins represent an exciting class of novel drug targets. RGS2, in particular, could have broad clinical importance. As more details are emerging on the regulation of RGS2 in various physiological systems, the potential utility of this small protein in therapeutic development is increasing.
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Affiliation(s)
- Harrison J McNabb
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Qian Zhang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Benita Sjögren
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
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Valkov N, King ME, Moeller J, Liu H, Li X, Zhang P. MicroRNA-1-Mediated Inhibition of Cardiac Fibroblast Proliferation Through Targeting Cyclin D2 and CDK6. Front Cardiovasc Med 2019; 6:65. [PMID: 31157242 PMCID: PMC6533459 DOI: 10.3389/fcvm.2019.00065] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 05/01/2019] [Indexed: 12/24/2022] Open
Abstract
MicroRNA-1 (miRNA-1) has been long viewed as a muscle-specific miRNA and plays a critical role in myocardium and cardiomyocytes by controlling myocyte growth and rhythm. We identified that miRNA-1 is expressed in cardiac fibroblasts, which are one of the major non-muscle cell types in myocardium and are responsible for cardiac fibrosis in pathological conditions. In this study, we aimed to investigate the effect and mechanism of action of miRNA-1 on cardiac fibroblast proliferation. Subcutaneous angiotensin II (Ang II) infusion via osmotic minipumps for 4 weeks was used to induce myocardial interstitial fibrosis in male Sprague-Dawley rats. MiRNA-1 expression was significantly down-regulated by 68% in freshly isolated ventricular fibroblasts from Ang II-infused rats than that from control rats. Similar results were obtained in adult rat ventricular fibroblasts that were stimulated in culture by Ang II or TGFβ for 48 h. Functionally, overexpression of miRNA-1 inhibited fibroblast proliferation, whereas knockdown of endogenous miRNA-1 increased fibroblast proliferation. We then identified and validated cyclin D2 and cyclin-dependent kinase 6 (CDK6) as direct targets of miRNA-1 in cardiac fibroblasts using biochemical assays. Moreover, we showed that the inhibitory effects of miRNA-1 on cardiac fibroblast proliferation can be blunted by overexpression of its target, cyclin D2. In conclusion, our findings demonstrate miRNA-1 expression and regulation in adult ventricular fibroblasts, where it acts as a novel negative regulator of adult cardiac fibroblast proliferation that is at least partially mediated by direct targeting of two cell cycle regulators. Our results expand the understanding of the regulatory roles of miRNA-1 in cardiac cells (i.e., from myocytes to a major non-muscle cells in the heart).
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Affiliation(s)
- Nedyalka Valkov
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, RI, United States.,Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI, United States
| | - Michelle E King
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, RI, United States
| | - Jacob Moeller
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, RI, United States
| | - Hong Liu
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, RI, United States
| | - Xiaofei Li
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, RI, United States
| | - Peng Zhang
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, RI, United States
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10
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Wang CHJ, Chidiac P. RGS2 promotes the translation of stress-associated proteins ATF4 and CHOP via its eIF2B-inhibitory domain. Cell Signal 2019; 59:163-170. [PMID: 30826455 DOI: 10.1016/j.cellsig.2019.02.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 02/15/2019] [Accepted: 02/26/2019] [Indexed: 12/25/2022]
Abstract
Regulator of G protein signaling 2 (RGS2) is upregulated by multiple forms of stress and can augment translational attenuation associated with the phosphorylation of the initiation factor eIF2, a hallmark of several stress-induced coping mechanisms. Under stress-induced translational inhibition, key factors, such as ATF4, are selectively expressed via alternative translation mechanisms. These factors are known to regulate molecular switches that control cell fate by regulating pro-survival and pro-apoptotic signals. The molecular mechanisms that balance these opposing responses to stresses are unclear. The present results suggest that RGS2 may be an important regulatory component in the cellular stress response through its translational control abilities. Previously, we have shown that RGS2 can interact with the translation initiation factor, eIF2B, and inhibit de novo protein synthesis. Here, we demonstrate that the expression of either full length RGS2 or its eIF2B-interacting domain (RGS2eb) significantly increases levels of ATF4 and CHOP, both of which are linked to stress-induced apoptosis. Furthermore, we show that these effects are translationally regulated and independent of eIF2 phosphorylation. The present results thus point to a novel function of RGS2 in the stress response directly related to its ability to reduce global protein synthesis.
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Affiliation(s)
- Chang-Hui Jenny Wang
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Peter Chidiac
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada; Department of Biology, Faculty of Science, University of Western Ontario, London, Ontario N6A 5B7, Canada.
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11
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Morhenn K, Quentin T, Wichmann H, Steinmetz M, Prondzynski M, Söhren KD, Christ T, Geertz B, Schröder S, Schöndube FA, Hasenfuss G, Schlossarek S, Zimmermann WH, Carrier L, Eschenhagen T, Cardinaux JR, Lutz S, Oetjen E. Mechanistic role of the CREB-regulated transcription coactivator 1 in cardiac hypertrophy. J Mol Cell Cardiol 2018; 127:31-43. [PMID: 30521840 DOI: 10.1016/j.yjmcc.2018.12.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 11/27/2018] [Accepted: 12/02/2018] [Indexed: 10/27/2022]
Abstract
The sympathetic nervous system is the main stimulator of cardiac function. While acute activation of the β-adrenoceptors exerts positive inotropic and lusitropic effects by increasing cAMP and Ca2+, chronically enhanced sympathetic tone with changed β-adrenergic signaling leads to alterations of gene expression and remodeling. The CREB-regulated transcription coactivator 1 (CRTC1) is activated by cAMP and Ca2+. In the present study, the regulation of CRTC1 in cardiomyocytes and its effect on cardiac function and growth was investigated. In cardiomyocytes, isoprenaline induced dephosphorylation, and thus activation of CRTC1, which was prevented by propranolol. Crtc1-deficient mice exhibited left ventricular dysfunction, hypertrophy and enlarged cardiomyocytes. However, isoprenaline-induced contractility of isolated trabeculae or phosphorylation of cardiac troponin I, cardiac myosin-binding protein C, phospholamban, and ryanodine receptor were not altered, suggesting that cardiac dysfunction was due to the global lack of Crtc1. The mRNA and protein levels of the Gαq GTPase activating protein regulator of G-protein signaling 2 (RGS2) were lower in hearts of Crtc1-deficient mice. Chromatin immunoprecipitation and reporter gene assays showed stimulation of the Rgs2 promoter by CRTC1. In Crtc1-deficient cardiomyocytes, phosphorylation of the Gαq-downstream kinase ERK was enhanced. CRTC1 content was higher in cardiac tissue from patients with aortic stenosis or hypertrophic cardiomyopathy and from two murine models mimicking these diseases. These data suggest that increased CRTC1 in maladaptive hypertrophy presents a compensatory mechanism to delay disease progression in part by enhancing Rgs2 gene transcription. Furthermore, the present study demonstrates an important role of CRTC1 in the regulation of cardiac function and growth.
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Affiliation(s)
- Karoline Morhenn
- Department of Clinical Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany; DZHK (German Center for Cardiovascular Research), Partner Site Hamburg, Kiel, Lübeck, Germany
| | - Thomas Quentin
- Department of Clinical Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Helen Wichmann
- Department of Pediatric Cardiology and Intensive Medicine, University Medical Center Göttingen, Robert Koch Str. 40, 37075 Göttingen, Germany
| | - Michael Steinmetz
- Department of Pediatric Cardiology and Intensive Medicine, University Medical Center Göttingen, Robert Koch Str. 40, 37075 Göttingen, Germany; DZHK (German Center for Cardiovascular Research), Partner Site, Göttingen, Germany
| | - Maksymilian Prondzynski
- DZHK (German Center for Cardiovascular Research), Partner Site Hamburg, Kiel, Lübeck, Germany; Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Klaus-Dieter Söhren
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Torsten Christ
- DZHK (German Center for Cardiovascular Research), Partner Site Hamburg, Kiel, Lübeck, Germany; Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Birgit Geertz
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Sabine Schröder
- Department of Clinical Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Friedrich A Schöndube
- Department of Thoracic-Cardiac and Vascular Surgery, University Medical Center Göttingen, Robert Koch Str. 40, 37075 Göttingen, Germany
| | - Gerd Hasenfuss
- DZHK (German Center for Cardiovascular Research), Partner Site, Göttingen, Germany; Department of Cardiology and Pneumology, University Medical Center Göttingen, Robert Koch Str. 40, 37075 Göttingen, Germany
| | - Saskia Schlossarek
- DZHK (German Center for Cardiovascular Research), Partner Site Hamburg, Kiel, Lübeck, Germany; Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Wolfram H Zimmermann
- DZHK (German Center for Cardiovascular Research), Partner Site, Göttingen, Germany; Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Robert Koch Str. 40, 37075 Göttingen, Germany
| | - Lucie Carrier
- DZHK (German Center for Cardiovascular Research), Partner Site Hamburg, Kiel, Lübeck, Germany; Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Thomas Eschenhagen
- DZHK (German Center for Cardiovascular Research), Partner Site Hamburg, Kiel, Lübeck, Germany; Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Jean-René Cardinaux
- Center for Psychiatric Neuroscience and Service of Child and Adolescent Psychiatry, Department of Psychiatry, University Medical Center, University of Lausanne, 1008 Prilly-Lausanne, Switzerland
| | - Susanne Lutz
- DZHK (German Center for Cardiovascular Research), Partner Site, Göttingen, Germany; Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Robert Koch Str. 40, 37075 Göttingen, Germany
| | - Elke Oetjen
- Department of Clinical Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany; DZHK (German Center for Cardiovascular Research), Partner Site Hamburg, Kiel, Lübeck, Germany; Institute of Pharmacy, University of Hamburg, Bundesstr. 45, 20146 Hamburg, Germany.
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12
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Interplay between negative and positive design elements in Gα helical domains of G proteins determines interaction specificity toward RGS2. Biochem J 2018; 475:2293-2304. [PMID: 29925530 DOI: 10.1042/bcj20180285] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 06/18/2018] [Accepted: 06/19/2018] [Indexed: 01/26/2023]
Abstract
Regulators of G protein signaling (RGS) proteins inactivate Gα subunits, thereby controlling G protein-coupled signaling networks. Among all RGS proteins, RGS2 is unique in interacting only with the Gαq but not with the Gαi subfamily. Previous studies suggested that this specificity is determined by the RGS domain and, in particular, by three RGS2-specific residues that lead to a unique mode of interaction with Gαq This interaction was further proposed to act through contacts with the Gα GTPase domain. Here, we combined energy calculations and GTPase activity measurements to determine which Gα residues dictate specificity toward RGS2. We identified putative specificity-determining residues in the Gα helical domain, which among G proteins is found only in Gα subunits. Replacing these helical domain residues in Gαi with their Gαq counterparts resulted in a dramatic specificity switch toward RGS2. We further show that Gα-RGS2 specificity is set by Gαi residues that perturb interactions with RGS2, and by Gαq residues that enhance these interactions. These results show, for the first time, that the Gα helical domain is central to dictating specificity toward RGS2, suggesting that this domain plays a general role in governing Gα-RGS specificity. Our insights provide new options for manipulating RGS-G protein interactions in vivo, for better understanding of their 'wiring' into signaling networks, and for devising novel drugs targeting such interactions.
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Alqinyah M, Hooks SB. Regulating the regulators: Epigenetic, transcriptional, and post-translational regulation of RGS proteins. Cell Signal 2017; 42:77-87. [PMID: 29042285 DOI: 10.1016/j.cellsig.2017.10.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 10/06/2017] [Accepted: 10/13/2017] [Indexed: 12/11/2022]
Abstract
Regulators of G protein signaling (RGS) are a family of proteins classically known to accelerate the intrinsic GTPase activity of G proteins, which results in accelerated inactivation of heterotrimeric G proteins and inhibition of G protein coupled receptor signaling. RGS proteins play major roles in essential cellular processes, and dysregulation of RGS protein expression is implicated in multiple diseases, including cancer, cardiovascular and neurodegenerative diseases. The expression of RGS proteins is highly dynamic and is regulated by epigenetic, transcriptional and post-translational mechanisms. This review summarizes studies that report dysregulation of RGS protein expression in disease states, and presents examples of drugs that regulate RGS protein expression. Additionally, this review discusses, in detail, the transcriptional and post-transcriptional mechanisms regulating RGS protein expression, and further assesses the therapeutic potential of targeting these mechanisms. Understanding the molecular mechanisms controlling the expression of RGS proteins is essential for the development of therapeutics that indirectly modulate G protein signaling by regulating expression of RGS proteins.
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Affiliation(s)
- Mohammed Alqinyah
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, USA
| | - Shelley B Hooks
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, USA.
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Kanai SM, Edwards AJ, Rurik JG, Osei-Owusu P, Blumer KJ. Proteolytic degradation of regulator of G protein signaling 2 facilitates temporal regulation of G q/11 signaling and vascular contraction. J Biol Chem 2017; 292:19266-19278. [PMID: 28974581 DOI: 10.1074/jbc.m117.797134] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 09/18/2017] [Indexed: 12/18/2022] Open
Abstract
Regulator of G protein signaling 2 (RGS2) controls signaling by receptors coupled to the Gq/11 class heterotrimeric G proteins. RGS2 deficiency causes several phenotypes in mice and occurs in several diseases, including hypertension in which a proteolytically unstable RGS2 mutant has been reported. However, the mechanisms and functions of RGS2 proteolysis remain poorly understood. Here we addressed these questions by identifying degradation signals in RGS2, and studying dynamic regulation of Gq/11-evoked Ca2+ signaling and vascular contraction. We identified a novel bipartite degradation signal in the N-terminal domain of RGS2. Mutations disrupting this signal blunted proteolytic degradation downstream of E3 ubiquitin ligase binding to RGS2. Analysis of RGS2 mutants proteolyzed at various rates and the effects of proteasome inhibition indicated that proteolytic degradation controls agonist efficacy by setting RGS2 protein expression levels, and affecting the rate at which cells regain agonist responsiveness as synthesis of RGS2 stops. Analyzing contraction of mesenteric resistance arteries supported the biological relevance of this mechanism. Because RGS2 mRNA expression often is strikingly and transiently up-regulated and then down-regulated upon cell stimulation, our findings indicate that proteolytic degradation tightly couples RGS2 transcription, protein levels, and function. Together these mechanisms provide tight temporal control of Gq/11-coupled receptor signaling in the cardiovascular, immune, and nervous systems.
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Affiliation(s)
- Stanley M Kanai
- From the Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | - Alethia J Edwards
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102
| | - Joel G Rurik
- From the Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | - Patrick Osei-Owusu
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102
| | - Kendall J Blumer
- From the Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110 and
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15
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Phan HTN, Sjögren B, Neubig RR. Human Missense Mutations in Regulator of G Protein Signaling 2 Affect the Protein Function Through Multiple Mechanisms. Mol Pharmacol 2017; 92:451-458. [PMID: 28784619 DOI: 10.1124/mol.117.109215] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 08/02/2017] [Indexed: 01/11/2023] Open
Abstract
Regulator of G protein signaling 2 (RGS2) plays a significant role in alleviating vascular contraction and promoting vascular relaxation due to its GTPase accelerating protein activity toward Gαq. Mice lacking RGS2 display a hypertensive phenotype, and several RGS2 missense mutations have been found predominantly in hypertensive human subjects. However, the mechanisms whereby these mutations could impact blood pressure is unknown. Here, we selected 16 rare, missense mutations in RGS2 identified in various human exome sequencing projects and evaluated their ability to inhibit intracellular calcium release mediated by angiotensin II receptor type 1 (AT1R). Four of them had reduced function and were further investigated to elucidate underlying mechanisms. Low protein expression, protein mislocalization, and reduced G protein binding were identified as likely mechanisms of the malfunctioning mutants. The Q2L mutant had 50% lower RGS2 than wild-type (WT) protein detected by Western blot. Confocal microscopy demonstrated that R44H and D40Y had impaired plasma membrane targeting; only 46% and 35% of those proteins translocated to the plasma membrane when coexpressed with Gαq Q209L compared with 67% for WT RGS2. The R188H mutant had a significant reduction in Gαq binding affinity (10-fold increase in Ki compared with WT RGS2 in a flow cytometry competition binding assay). This study provides functional data for 16 human RGS2 missense variants on their effects on AT1R-mediated calcium mobilization and provides molecular understanding of those variants with functional loss in vitro. These molecular behaviors can provide insight to inform antihypertensive therapeutics in individuals with variants having reduced function.
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Affiliation(s)
- Hoa T N Phan
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Benita Sjögren
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Richard R Neubig
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
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16
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Lee KN, Lu X, Nguyen C, Feng Q, Chidiac P. Cardiomyocyte specific overexpression of a 37 amino acid domain of regulator of G protein signalling 2 inhibits cardiac hypertrophy and improves function in response to pressure overload in mice. J Mol Cell Cardiol 2017. [PMID: 28641980 DOI: 10.1016/j.yjmcc.2017.06.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Regulator of G protein signalling 2 (RGS2) is known to play a protective role in maladaptive cardiac hypertrophy and heart failure via its ability to inhibit Gq- and Gs- mediated GPCR signalling. We previously demonstrated that RGS2 can also inhibit protein translation and can thereby attenuate cell growth. This G protein-independent inhibitory effect has been mapped to a 37 amino acid domain (RGS2eb) within RGS2 that binds to eukaryotic initiation factor 2B (eIF2B). When expressed in neonatal rat cardiomyocytes, RGS2eb attenuates both protein synthesis and hypertrophy induced by Gq- and Gs- activating agents. In the current study, we investigated the potential cardioprotective role of RGS2eb by determining whether RGS2eb transgenic (RGS2eb TG) mice with cardiomyocyte specific overexpression of RGS2eb show resistance to the development of hypertrophy in comparison to wild-type (WT) controls. Using transverse aortic constriction (TAC) in a pressure-overload hypertrophy model, we demonstrated that cardiac hypertrophy was inhibited in RGS2eb TG mice compared to WT controls following four weeks of TAC. Expression of the hypertrophic markers atrial natriuretic peptide (ANP) and β-myosin heavy chain (MHC-β) was also reduced in RGS2eb TG compared to WT TAC animals. Furthermore, cardiac function in RGS2eb TG TAC mice was significantly improved compared to WT TAC mice. Notably, cardiomyocyte cell size was significantly decreased in TG compared to WT TAC mice. These results suggest that RGS2 may limit pathological cardiac hypertrophy at least in part via the function of its eIF2B-binding domain.
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Affiliation(s)
- Katherine N Lee
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON, N6A5C1, Canada
| | - Xiangru Lu
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON, N6A5C1, Canada
| | - Chau Nguyen
- School of Pharmacy, D'Youville College, Buffalo, New York 14201, USA
| | - Qingping Feng
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON, N6A5C1, Canada
| | - Peter Chidiac
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON, N6A5C1, Canada.
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Hypertrophy changes 3D shape of hiPSC-cardiomyocytes: Implications for cellular maturation in regenerative medicine. Cell Mol Bioeng 2016; 10:54-62. [PMID: 28163790 DOI: 10.1007/s12195-016-0462-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Advances in the use of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes for heart regeneration and in vitro disease models demand a greater understanding of how these cells grow and mature in 3-dimensional space. In this study, we developed an analysis methodology of single cardiomyocytes plated on 2D surfaces to assess their 3D myofilament volume and its z-height distribution, or shape, upon hypertrophic stimulation via phenylephrine (PE) treatment or long-term culture ("aging"). Cardiomyocytes were fixed and labeled with α-actinin for confocal microscopy imaging to obtain z-stacks for 3D myofilament volume analysis. In primary neonatal rat ventricular myocytes (NRVMs), area increased 72% with PE, while volume increased 31%. In hiPSC-cardiomyocytes, area increased 70% with PE and 4-fold with aging; however, volume increased significantly only with aging by 2.3-fold. Analysis of z-height myofilament volume distribution in hiPSC-cardiomyocytes revealed a shift from a fairly uniform distribution in control cells to a basally located volume in a more flat and spread morphology with PE and even more so with aging, a shape that was akin to all NRVMs analyzed. These results suggest that 2D area is not a sufficient measure of hiPSC-cardiomyocyte growth and maturation, and that changes in 3D volume and its distribution are essential for understanding hiPSC-cardiomyocyte biology for disease modeling and regenerative medicine applications.
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Abstract
In the classical two-state model, G protein-coupled receptors (GPCRs) are considered to exist in equilibrium between an active and an inactive conformation. Thus, even at the resting state, some subpopulation of GPCRs is in the active state, which underlies the basal activity of the GPCRs. In this review, we discuss inverse agonists, which are defined as GPCR ligands that shift the equilibrium toward the inactive state and thereby suppress the basal activity. Theoretically, if constitutive activation plays an essential role in the pathogenesis of a disease, only inverse agonists, and not neutral antagonists, can reverse this pathophysiological activation. Although many pharmacological examples of inverse agonism have been identified, its clinical importance is still unclear and debated. Thus, even though inverse agonism of angiotensin receptor blockers (ARBs) has been discussed for more than 10 years, its clinical relevance remains to be completely clarified.
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Affiliation(s)
- Junichiro Sato
- Department of Endocrinology and Nephrology, The University of Tokyo School of Medicine, Tokyo 113-8655, Japan
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Sjögren B, Parra S, Atkins KB, Karaj B, Neubig RR. Digoxin-Mediated Upregulation of RGS2 Protein Protects against Cardiac Injury. J Pharmacol Exp Ther 2016; 357:311-9. [PMID: 26941169 PMCID: PMC4851323 DOI: 10.1124/jpet.115.231571] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 03/01/2016] [Indexed: 12/31/2022] Open
Abstract
Regulator of G protein signaling (RGS) proteins have emerged as novel drug targets since their discovery almost two decades ago. RGS2 has received particular interest in cardiovascular research due to its role in regulating Gqsignaling in the heart and vascular smooth muscle. RGS2(-/-)mice are hypertensive, prone to heart failure, and display accelerated kidney fibrosis. RGS2 is rapidly degraded through the proteasome, and human mutations leading to accelerated RGS2 protein degradation correlate with hypertension. Hence, stabilizing RGS2 protein expression could be a novel route in treating cardiovascular disease. We previously identified cardiotonic steroids, including digoxin, as selective stabilizers of RGS2 protein in vitro. In the current study we investigated the functional effects of digoxin-mediated RGS2 protein stabilization in vivo. Using freshly isolated myocytes from wild-type and RGS2(-/-)mice treated with vehicle or low-dose digoxin (2µg/kg/day for 7 days) we demonstrated that agonist-induced cAMP levels and cardiomyocyte contractility was inhibited by digoxin in wild-type but not in RGS2(-/-)mice. This inhibition was accompanied by an increase in RGS2 protein levels in cardiomyocytes as well as in whole heart tissue. Furthermore, digoxin had protective effects in a model of cardiac injury in wild-type mice and this protection was lost in RGS2(-/-)mice. Digoxin is the oldest known therapy for heart failure; however, beyond its activity at the Na(+)/K(+)-ATPase, the exact mechanism of action is not known. The current study adds a novel mechanism, whereby through stabilizing RGS2 protein levels digoxin could exert its protective effects in the failing heart.
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Affiliation(s)
- Benita Sjögren
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (B.S., B.K., R.R.N.); and Department of Pharmacology (S.P.) and Department of Internal Medicine (K.B.A.), University of Michigan, Ann Arbor, Michigan
| | - Sergio Parra
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (B.S., B.K., R.R.N.); and Department of Pharmacology (S.P.) and Department of Internal Medicine (K.B.A.), University of Michigan, Ann Arbor, Michigan
| | - Kevin B Atkins
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (B.S., B.K., R.R.N.); and Department of Pharmacology (S.P.) and Department of Internal Medicine (K.B.A.), University of Michigan, Ann Arbor, Michigan
| | - Behirda Karaj
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (B.S., B.K., R.R.N.); and Department of Pharmacology (S.P.) and Department of Internal Medicine (K.B.A.), University of Michigan, Ann Arbor, Michigan
| | - Richard R Neubig
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (B.S., B.K., R.R.N.); and Department of Pharmacology (S.P.) and Department of Internal Medicine (K.B.A.), University of Michigan, Ann Arbor, Michigan
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20
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Doupnik CA. RGS Redundancy and Implications in GPCR-GIRK Signaling. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 123:87-116. [PMID: 26422983 DOI: 10.1016/bs.irn.2015.05.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Regulators of G protein signaling (RGS proteins) are key components of GPCR complexes, interacting directly with G protein α-subunits to enhance their intrinsic GTPase activity. The functional consequence is an accelerated termination of G protein effectors including certain ion channels. RGS proteins have a profound impact on the membrane-delimited gating behavior of G-protein-activated inwardly rectifying K(+) (GIRK) channels as demonstrated in reconstitution assays and recent RGS knockout mice studies. Akin to GPCRs and G protein αβγ subunits, multiple RGS isoforms are expressed within single GIRK-expressing neurons, suggesting functional redundancy and/or specificity in GPCR-GIRK channel signaling. The extent and impact of RGS redundancy in neuronal GPCR-GIRK channel signaling is currently not fully appreciated; however, recent studies from RGS knockout mice are providing important new clues on the impact of individual endogenous RGS proteins and the extent of RGS functional redundancy. Incorporating "tools" such as engineered RGS-resistant Gαi/o subunits provide an important assessment method for determining the impact of all endogenous RGS proteins on a given GPCR response and an accounting benchmark to assess the impact of individual RGS knockouts on overall RGS redundancy within a given neuron. Elucidating the degree of regulation attributable to specific RGS proteins in GIRK channel function will aid in the assessment of individual RGS proteins as viable therapeutic targets in epilepsy, ataxia's, memory disorders, and a growing list of neurological disorders.
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Affiliation(s)
- Craig A Doupnik
- Department of Molecular Pharmacology & Physiology, University of South Florida College of Medicine, Tampa, Florida, USA.
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21
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Sjögren B, Swaney S, Neubig RR. FBXO44-Mediated Degradation of RGS2 Protein Uniquely Depends on a Cullin 4B/DDB1 Complex. PLoS One 2015; 10:e0123581. [PMID: 25970626 PMCID: PMC4430315 DOI: 10.1371/journal.pone.0123581] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 03/05/2015] [Indexed: 12/30/2022] Open
Abstract
The ubiquitin-proteasome system for protein degradation plays a major role in regulating cell function and many signaling proteins are tightly controlled by this mechanism. Among these, Regulator of G Protein Signaling 2 (RGS2) is a target for rapid proteasomal degradation, however, the specific enzymes involved are not known. Using a genomic siRNA screening approach, we identified a novel E3 ligase complex containing cullin 4B (CUL4B), DNA damage binding protein 1 (DDB1) and F-box protein 44 (FBXO44) that mediates RGS2 protein degradation. While the more typical F-box partners CUL1 and Skp1 can bind FBXO44, that E3 ligase complex does not bind RGS2 and is not involved in RGS2 degradation. These observations define an unexpected DDB1/CUL4B-containing FBXO44 E3 ligase complex. Pharmacological targeting of this mechanism provides a novel therapeutic approach to hypertension, anxiety, and other diseases associated with RGS2 dysregulation.
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Affiliation(s)
- Benita Sjögren
- Department of Pharmacology & Toxicology, Michigan State University, 1355 Bogue Street, East Lansing, MI 48824, United States of America
| | - Steven Swaney
- Center for Chemical Genomics, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109, United States of America
| | - Richard R Neubig
- Department of Pharmacology & Toxicology, Michigan State University, 1355 Bogue Street, East Lansing, MI 48824, United States of America
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22
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Woodard GE, Jardín I, Berna-Erro A, Salido GM, Rosado JA. Regulators of G-protein-signaling proteins: negative modulators of G-protein-coupled receptor signaling. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 317:97-183. [PMID: 26008785 DOI: 10.1016/bs.ircmb.2015.02.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Regulators of G-protein-signaling (RGS) proteins are a category of intracellular proteins that have an inhibitory effect on the intracellular signaling produced by G-protein-coupled receptors (GPCRs). RGS along with RGS-like proteins switch on through direct contact G-alpha subunits providing a variety of intracellular functions through intracellular signaling. RGS proteins have a common RGS domain that binds to G alpha. RGS proteins accelerate GTPase and thus enhance guanosine triphosphate hydrolysis through the alpha subunit of heterotrimeric G proteins. As a result, they inactivate the G protein and quickly turn off GPCR signaling thus terminating the resulting downstream signals. Activity and subcellular localization of RGS proteins can be changed through covalent molecular changes to the enzyme, differential gene splicing, and processing of the protein. Other roles of RGS proteins have shown them to not be solely committed to being inhibitors but behave more as modulators and integrators of signaling. RGS proteins modulate the duration and kinetics of slow calcium oscillations and rapid phototransduction and ion signaling events. In other cases, RGS proteins integrate G proteins with signaling pathways linked to such diverse cellular responses as cell growth and differentiation, cell motility, and intracellular trafficking. Human and animal studies have revealed that RGS proteins play a vital role in physiology and can be ideal targets for diseases such as those related to addiction where receptor signaling seems continuously switched on.
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Affiliation(s)
- Geoffrey E Woodard
- Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD, USA; Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | - Isaac Jardín
- Department of Physiology, University of Extremadura, Caceres, Spain
| | - A Berna-Erro
- Department of Physiology, University of Extremadura, Caceres, Spain
| | - Gines M Salido
- Department of Physiology, University of Extremadura, Caceres, Spain
| | - Juan A Rosado
- Department of Physiology, University of Extremadura, Caceres, Spain
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Mao Y, Su J, Lei L, Meng L, Qi Y, Huo Y, Tang C. Impaired regulator of G protein signaling 2 transcription facilitates vascular remodeling in injured rat aorta. J Cardiovasc Med (Hagerstown) 2015; 15:572-8. [PMID: 24914635 DOI: 10.2459/jcm.0b013e3283629c30] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND The activation of Gq-protein-coupled receptors induces proliferation of vascular smooth muscle cells (VSMCs) proliferation and is involved in vascular remodeling. The regulator of G protein signaling 2 (RGS2), which accelerates the termination of Gq protein signaling, may play a role in vascular remodeling. However, this role remains unclear. METHODS Aortic balloon injury or sham operation was produced in male Wistar rats. Histological examination and gene expression analysis were performed after surgery. In cultured VSMCs after modulation of RGS2 expression, cell proliferation was also evaluated. RESULTS At day 3 after injury, RGS2 transcription was reduced by 52.8% (P <0.05 vs. sham group) with vascular remodeling. In cultured VSMCs stimulated by endothelin-1, phenylephrine or angiotensin II, the proliferation of RGS2 overexpressed cells was significantly inhibited; the proliferation of RGS2 downregulated cells was significantly promoted, compared with that of RGS2 normal cells. Moreover, after incubation with angiotensin II of high concentration (>10 μmol/l) or long term (>8 h), the RGS2 expression was clearly downregulated in cultured VSMCs. Administration of an angiotensin receptor blocker, valsartan (20 mg/kg per day) starting from 1 week preballoon injury to 3 days after injury, restored aortic RGS2 transcription and improved vascular remodeling. CONCLUSION These results suggested that the inhibiting effect of RGS2 on VSMC proliferation is downregulated in vascular remodeling of injured rat aorta, and this effect is likely to be mediated by angiotensin II signaling.
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Affiliation(s)
- Yuanjie Mao
- aDepartment of Cardiology, Peking University First Hospital, Beijing, China bDepartment of Biochemistry, National Cerebral and Cardiovascular Center, Osaka, Japan cCardiology Division, Cardiovascular Research Center, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island, USA dDepartment of Endocrinology, Beijing Aerospace Center Hospital eDepartment of Physiology, School of Basic Medical Sciences, Peking University, Beijing, China
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24
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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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25
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Raveh A, Schultz PJ, Aschermann L, Carpenter C, Tamayo-Castillo G, Cao S, Clardy J, Neubig RR, Sherman DH, Sjögren B. Identification of protein kinase C activation as a novel mechanism for RGS2 protein upregulation through phenotypic screening of natural product extracts. Mol Pharmacol 2014; 86:406-16. [PMID: 25086086 DOI: 10.1124/mol.114.092403] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Biochemical high-throughput screening is widely used in drug discovery, using a variety of small molecule libraries. However, broader screening strategies may be more beneficial to identify novel biologic mechanisms. In the current study we used a β-galactosidase complementation method to screen a selection of microbial-derived pre-fractionated natural product extracts for those that increase regulator of G protein signaling 2 (RGS2) protein levels. RGS2 is a member of a large family of proteins that all regulate signaling through G protein-coupled receptors (GPCRs) by accelerating GTPase activity on active Gα as well as through other mechanisms. RGS2(-/-) mice are hypertensive, show increased anxiety, and are prone to heart failure. RGS2 has a very short protein half-life due to rapid proteasomal degradation, and we propose that enhancement of RGS2 protein levels could be a beneficial therapeutic strategy. Bioassay-guided fractionation of one of the hit strains yielded a pure compound, Indolactam V, a known protein kinase C (PKC) activator, which selectively increased RGS2 protein levels in a time- and concentration-dependent manner. Similar results were obtained with phorbol 12-myristate 13-acetate as well as activation of the Gq-coupled muscarinic M3 receptor. The effect on RGS2 protein levels was blocked by the nonselective PKC inhibitor Gö6983 (3-[1-[3-(dimethylamino)propyl]-5-methoxy-1H-indol-3-yl]-4-(1H-indol-3-yl)-1H-pyrrole-2,5-dione), the PKCβ-selective inhibitor Ruboxastaurin, as well as small interfering RNA-mediated knockdown of PKCβ. Indolactam V-mediated increases in RGS2 protein levels also had functional effects on GPCR signaling. This study provides important proof-of-concept for our screening strategy and could define a negative feedback mechanism in Gq/Phospholipase C signaling through RGS2 protein upregulation.
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Affiliation(s)
- Avi Raveh
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan (A.R., P.J.S., D.H.S.); Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan (L.A., R.R.N., B.S.); Department of Pharmacology (C.C.), Department of Medicinal Chemistry (D.H.S.), Department of Microbiology and Immunology (D.H.S.), Department of Chemistry (D.H.S.), Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (D.H.S.); Unidad Estrategica de Bioprospección, Instituto Nacional de Biodiversidad, Santo Domingo de Heredia, Costa Rica & CIPRONA, Escuela de Química, Universidad de Costa Rica, San Pedro, Costa Rica (G.T-C.); Harvard Medical School, Boston, Massachusetts (S.C., J.C.); and University of Hawaii Cancer Center, Honolulu, Hawaii (S.C.)
| | - Pamela J Schultz
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan (A.R., P.J.S., D.H.S.); Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan (L.A., R.R.N., B.S.); Department of Pharmacology (C.C.), Department of Medicinal Chemistry (D.H.S.), Department of Microbiology and Immunology (D.H.S.), Department of Chemistry (D.H.S.), Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (D.H.S.); Unidad Estrategica de Bioprospección, Instituto Nacional de Biodiversidad, Santo Domingo de Heredia, Costa Rica & CIPRONA, Escuela de Química, Universidad de Costa Rica, San Pedro, Costa Rica (G.T-C.); Harvard Medical School, Boston, Massachusetts (S.C., J.C.); and University of Hawaii Cancer Center, Honolulu, Hawaii (S.C.)
| | - Lauren Aschermann
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan (A.R., P.J.S., D.H.S.); Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan (L.A., R.R.N., B.S.); Department of Pharmacology (C.C.), Department of Medicinal Chemistry (D.H.S.), Department of Microbiology and Immunology (D.H.S.), Department of Chemistry (D.H.S.), Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (D.H.S.); Unidad Estrategica de Bioprospección, Instituto Nacional de Biodiversidad, Santo Domingo de Heredia, Costa Rica & CIPRONA, Escuela de Química, Universidad de Costa Rica, San Pedro, Costa Rica (G.T-C.); Harvard Medical School, Boston, Massachusetts (S.C., J.C.); and University of Hawaii Cancer Center, Honolulu, Hawaii (S.C.)
| | - Colleen Carpenter
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan (A.R., P.J.S., D.H.S.); Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan (L.A., R.R.N., B.S.); Department of Pharmacology (C.C.), Department of Medicinal Chemistry (D.H.S.), Department of Microbiology and Immunology (D.H.S.), Department of Chemistry (D.H.S.), Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (D.H.S.); Unidad Estrategica de Bioprospección, Instituto Nacional de Biodiversidad, Santo Domingo de Heredia, Costa Rica & CIPRONA, Escuela de Química, Universidad de Costa Rica, San Pedro, Costa Rica (G.T-C.); Harvard Medical School, Boston, Massachusetts (S.C., J.C.); and University of Hawaii Cancer Center, Honolulu, Hawaii (S.C.)
| | - Giselle Tamayo-Castillo
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan (A.R., P.J.S., D.H.S.); Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan (L.A., R.R.N., B.S.); Department of Pharmacology (C.C.), Department of Medicinal Chemistry (D.H.S.), Department of Microbiology and Immunology (D.H.S.), Department of Chemistry (D.H.S.), Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (D.H.S.); Unidad Estrategica de Bioprospección, Instituto Nacional de Biodiversidad, Santo Domingo de Heredia, Costa Rica & CIPRONA, Escuela de Química, Universidad de Costa Rica, San Pedro, Costa Rica (G.T-C.); Harvard Medical School, Boston, Massachusetts (S.C., J.C.); and University of Hawaii Cancer Center, Honolulu, Hawaii (S.C.)
| | - Shugeng Cao
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan (A.R., P.J.S., D.H.S.); Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan (L.A., R.R.N., B.S.); Department of Pharmacology (C.C.), Department of Medicinal Chemistry (D.H.S.), Department of Microbiology and Immunology (D.H.S.), Department of Chemistry (D.H.S.), Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (D.H.S.); Unidad Estrategica de Bioprospección, Instituto Nacional de Biodiversidad, Santo Domingo de Heredia, Costa Rica & CIPRONA, Escuela de Química, Universidad de Costa Rica, San Pedro, Costa Rica (G.T-C.); Harvard Medical School, Boston, Massachusetts (S.C., J.C.); and University of Hawaii Cancer Center, Honolulu, Hawaii (S.C.)
| | - Jon Clardy
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan (A.R., P.J.S., D.H.S.); Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan (L.A., R.R.N., B.S.); Department of Pharmacology (C.C.), Department of Medicinal Chemistry (D.H.S.), Department of Microbiology and Immunology (D.H.S.), Department of Chemistry (D.H.S.), Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (D.H.S.); Unidad Estrategica de Bioprospección, Instituto Nacional de Biodiversidad, Santo Domingo de Heredia, Costa Rica & CIPRONA, Escuela de Química, Universidad de Costa Rica, San Pedro, Costa Rica (G.T-C.); Harvard Medical School, Boston, Massachusetts (S.C., J.C.); and University of Hawaii Cancer Center, Honolulu, Hawaii (S.C.)
| | - Richard R Neubig
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan (A.R., P.J.S., D.H.S.); Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan (L.A., R.R.N., B.S.); Department of Pharmacology (C.C.), Department of Medicinal Chemistry (D.H.S.), Department of Microbiology and Immunology (D.H.S.), Department of Chemistry (D.H.S.), Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (D.H.S.); Unidad Estrategica de Bioprospección, Instituto Nacional de Biodiversidad, Santo Domingo de Heredia, Costa Rica & CIPRONA, Escuela de Química, Universidad de Costa Rica, San Pedro, Costa Rica (G.T-C.); Harvard Medical School, Boston, Massachusetts (S.C., J.C.); and University of Hawaii Cancer Center, Honolulu, Hawaii (S.C.)
| | - David H Sherman
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan (A.R., P.J.S., D.H.S.); Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan (L.A., R.R.N., B.S.); Department of Pharmacology (C.C.), Department of Medicinal Chemistry (D.H.S.), Department of Microbiology and Immunology (D.H.S.), Department of Chemistry (D.H.S.), Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (D.H.S.); Unidad Estrategica de Bioprospección, Instituto Nacional de Biodiversidad, Santo Domingo de Heredia, Costa Rica & CIPRONA, Escuela de Química, Universidad de Costa Rica, San Pedro, Costa Rica (G.T-C.); Harvard Medical School, Boston, Massachusetts (S.C., J.C.); and University of Hawaii Cancer Center, Honolulu, Hawaii (S.C.)
| | - Benita Sjögren
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan (A.R., P.J.S., D.H.S.); Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan (L.A., R.R.N., B.S.); Department of Pharmacology (C.C.), Department of Medicinal Chemistry (D.H.S.), Department of Microbiology and Immunology (D.H.S.), Department of Chemistry (D.H.S.), Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (D.H.S.); Unidad Estrategica de Bioprospección, Instituto Nacional de Biodiversidad, Santo Domingo de Heredia, Costa Rica & CIPRONA, Escuela de Química, Universidad de Costa Rica, San Pedro, Costa Rica (G.T-C.); Harvard Medical School, Boston, Massachusetts (S.C., J.C.); and University of Hawaii Cancer Center, Honolulu, Hawaii (S.C.)
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Alpha1a-adrenoceptor genetic variant induces cardiomyoblast-to-fibroblast-like cell transition via distinct signaling pathways. Cell Signal 2014; 26:1985-97. [PMID: 24835978 DOI: 10.1016/j.cellsig.2014.05.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 05/08/2014] [Accepted: 05/09/2014] [Indexed: 12/21/2022]
Abstract
The role of naturally occurring human α1a-Adrenergic Receptor (α1aAR) genetic variants associated with cardiovascular disorders is poorly understood. Here, we present the novel findings that expression of human α1aAR-247R (247R) genetic variant in cardiomyoblasts leads to transition of cardiomyoblasts into a fibroblast-like phenotype, evidenced by morphology and distinct de novo expression of characteristic genes. These fibroblast-like cells exhibit constitutive, high proliferative capacity and agonist-induced hypertrophy compared with cells prior to transition. We demonstrate that constitutive, synergistic activation of EGFR, Src and ERK kinases is the potential molecular mechanism of this transition. We also demonstrate that 247R triggers two distinct EGFR transactivation-dependent signaling pathways: 1) constitutive Gq-independent β-arrestin-1/Src/MMP/EGFR/ERK-dependent hyperproliferation and 2) agonist-induced Gq- and EGFR/STAT-dependent hypertrophy. Interestingly, in cardiomyoblasts agonist-independent hyperproliferation is MMP-dependent, but in fibroblast-like cells it is MMP-independent, suggesting that expression of α1aAR genetic variant in cardiomyocytes may trigger extracellular matrix remodeling. Thus, these novel findings demonstrate that EGFR transactivation by α1aAR-247R leads to hyperproliferation, hypertrophy and alterations in cardiomyoblasts, suggesting that these unique genetically-mediated alterations in signaling pathways and cellular function may lead to myocardial fibrosis. Such extracellular matrix remodeling may contribute to the genesis of arrhythmias in certain types of heart failure.
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27
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Chidiac P, Sobiesiak AJ, Lee KN, Gros R, Nguyen CH. The eIF2B-interacting domain of RGS2 protects against GPCR agonist-induced hypertrophy in neonatal rat cardiomyocytes. Cell Signal 2014; 26:1226-34. [PMID: 24576550 DOI: 10.1016/j.cellsig.2014.02.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 02/05/2014] [Accepted: 02/11/2014] [Indexed: 11/29/2022]
Abstract
The protective effect of Regulator of G protein Signaling 2 (RGS2) in cardiac hypertrophy is thought to occur through its ability to inhibit the chronic GPCR signaling that promotes pathogenic growth both in vivo and in cultured cardiomyocytes. However, RGS2 is known to have additional functions beyond its activity as a GTPase accelerating protein, such as the ability to bind to eukaryotic initiation factor, eIF2B, and inhibit protein synthesis. The RGS2 eIF2B-interacting domain (RGS2(eb)) was examined for its ability to regulate hypertrophy in neonatal ventricular myocytes. Both full-length RGS2 and RGS2(eb) were able to inhibit agonist-induced cardiomyocyte hypertrophy, but RGS2(eb) had no effect on receptor-mediated inositol phosphate production, cAMP production, or ERK 1/2 activation. These results suggest that the protective effects of RGS2 in cardiac hypertrophy may derive at least in part from its ability to govern protein synthesis.
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Affiliation(s)
- Peter Chidiac
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Alina J Sobiesiak
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Katherine N Lee
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Robert Gros
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Chau H Nguyen
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A 5C1, Canada; School of Pharmacy, D'Youville College, Buffalo, NY 14201, USA.
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28
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Huang MLH, Sivagurunathan S, Ting S, Jansson PJ, Austin CJD, Kelly M, Semsarian C, Zhang D, Richardson DR. Molecular and functional alterations in a mouse cardiac model of Friedreich ataxia: activation of the integrated stress response, eIF2α phosphorylation, and the induction of downstream targets. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 183:745-57. [PMID: 23886890 DOI: 10.1016/j.ajpath.2013.05.032] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 05/16/2013] [Accepted: 05/31/2013] [Indexed: 12/17/2022]
Abstract
Friedreich ataxia (FA) is a neurodegenerative and cardiodegenerative disease resulting from marked frataxin deficiency. The condition is characterized by ataxia with fatal cardiomyopathy, but the pathogenic mechanisms are unclear. We investigated the association between gene expression and progressive histopathological and functional changes using the muscle creatine kinase conditional frataxin knockout (KO) mouse; this mouse develops a severe cardiac phenotype that resembles that of FA patients. We examined KO mice from 3 weeks of age, when they are asymptomatic, to 10 weeks of age, when they die of the disease. Positive iron staining was identified in KO mice from 5 weeks of age, with markedly reduced cardiac function from 6 weeks. We identified an early and marked up-regulation of a gene cohort responsible for stress-induced amino acid biosynthesis and observed markedly increased phosphorylation of eukaryotic translation initiation factor 2α (p-eIF2α), an activator of the integrated stress response, in KO mice at 3 weeks of age, relative to wild-type mice. Importantly, the eIF2α-mediated integrated stress response has been previously implicated in heart failure via downstream processes such as autophagy and apoptosis. Indeed, expression of a panel of autophagy and apoptosis markers was enhanced in KO mice. Thus, the pathogenesis of cardiomyopathy in FA correlates with the early and persistent eIF2α phosphorylation, which precedes activation of autophagy and apoptosis.
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Affiliation(s)
- Michael Li-Hsuan Huang
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, Australia
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29
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Zhang P, Mende U. Functional role, mechanisms of regulation, and therapeutic potential of regulator of G protein signaling 2 in the heart. Trends Cardiovasc Med 2013; 24:85-93. [PMID: 23962825 DOI: 10.1016/j.tcm.2013.07.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 07/08/2013] [Accepted: 07/10/2013] [Indexed: 12/22/2022]
Abstract
G protein-mediated signal transduction is essential for the regulation of cardiovascular function, including heart rate, growth, contraction, and vascular tone. Regulators of G protein Signaling (RGS proteins) fine-tune G protein-coupled receptor-induced signaling by regulating its magnitude and duration through direct interaction with the α subunits of heterotrimeric G proteins. Changes in the RGS protein expression and/or function in the heart often lead to pathophysiological changes and are associated with cardiac disease in animals and humans, including hypertrophy, fibrosis development, heart failure, and arrhythmias. This article focuses on Regulator of G protein Signaling 2 (RGS2), which is widely expressed in many tissues and is highly regulated in its expression and function. Most information to date has been obtained in biochemical, cellular, and animal studies, but data from humans is emerging. We review recent advances on the functional role of cardiovascular RGS2 and the mechanisms that determine its signaling selectivity, expression, and functionality. We highlight key unanswered questions and discuss the potential of RGS2 as a therapeutic target.
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Affiliation(s)
- Peng Zhang
- Cardiovascular Research Center, Cardiology Division, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, RI, USA
| | - Ulrike Mende
- Cardiovascular Research Center, Cardiology Division, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, RI, USA.
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30
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Drawnel FM, Archer CR, Roderick HL. The role of the paracrine/autocrine mediator endothelin-1 in regulation of cardiac contractility and growth. Br J Pharmacol 2013; 168:296-317. [PMID: 22946456 DOI: 10.1111/j.1476-5381.2012.02195.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Revised: 08/23/2012] [Accepted: 08/28/2012] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Endothelin-1 (ET-1) is a critical autocrine and paracrine regulator of cardiac physiology and pathology. Produced locally within the myocardium in response to diverse mechanical and neurohormonal stimuli, ET-1 acutely modulates cardiac contractility. During pathological cardiovascular conditions such as ischaemia, left ventricular hypertrophy and heart failure, myocyte expression and activity of the entire ET-1 system is enhanced, allowing the peptide to both initiate and maintain maladaptive cellular responses. Both the acute and chronic effects of ET-1 are dependent on the activation of intracellular signalling pathways, regulated by the inositol-trisphosphate and diacylglycerol produced upon activation of the ET(A) receptor. Subsequent stimulation of protein kinases C and D, calmodulin-dependent kinase II, calcineurin and MAPKs modifies the systolic calcium transient, myofibril function and the activity of transcription factors that coordinate cellular remodelling. The precise nature of the cellular response to ET-1 is governed by the timing, localization and context of such signals, allowing the peptide to regulate both cardiomyocyte physiology and instigate disease. LINKED ARTICLES This article is part of a themed section on Endothelin. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.168.issue-1.
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Affiliation(s)
- Faye M Drawnel
- Babraham Research Campus, Babraham Institute, Cambridge, UK
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31
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Littlejohn NK, Siel RB, Ketsawatsomkron P, Pelham CJ, Pearson NA, Hilzendeger AM, Buehrer BA, Weidemann BJ, Li H, Davis DR, Thompson AP, Liu X, Cassell MD, Sigmund CD, Grobe JL. Hypertension in mice with transgenic activation of the brain renin-angiotensin system is vasopressin dependent. Am J Physiol Regul Integr Comp Physiol 2013; 304:R818-28. [PMID: 23535460 DOI: 10.1152/ajpregu.00082.2013] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
An indispensable role for the brain renin-angiotensin system (RAS) has been documented in most experimental animal models of hypertension. To identify the specific efferent pathway activated by the brain RAS that mediates hypertension, we examined the hypothesis that elevated arginine vasopressin (AVP) release is necessary for hypertension in a double-transgenic model of brain-specific RAS hyperactivity (the "sRA" mouse model). sRA mice experience elevated brain RAS activity due to human angiotensinogen expression plus neuron-specific human renin expression. Total daily loss of the 4-kDa AVP prosegment (copeptin) into urine was grossly elevated (≥8-fold). Immunohistochemical staining for AVP was increased in the supraoptic nucleus of sRA mice (~2-fold), but no quantitative difference in the paraventricular nucleus was observed. Chronic subcutaneous infusion of a nonselective AVP receptor antagonist conivaptan (YM-087, Vaprisol, 22 ng/h) or the V(2)-selective antagonist tolvaptan (OPC-41061, 22 ng/h) resulted in normalization of the baseline (~15 mmHg) hypertension in sRA mice. Abdominal aortas and second-order mesenteric arteries displayed AVP-specific desensitization, with minor or no changes in responses to phenylephrine and endothelin-1. Mesenteric arteries exhibited substantial reductions in V(1A) receptor mRNA, but no significant changes in V(2) receptor expression in kidney were observed. Chronic tolvaptan infusion also normalized the (5 mmol/l) hyponatremia of sRA mice. Together, these data support a major role for vasopressin in the hypertension of mice with brain-specific hyperactivity of the RAS and suggest a primary role of V(2) receptors.
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Affiliation(s)
- Nicole K Littlejohn
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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32
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Yang D, Lyashkov AE, Li Y, Ziman BD, Lakatta EG. RGS2 overexpression or G(i) inhibition rescues the impaired PKA signaling and slow AP firing of cultured adult rabbit pacemaker cells. J Mol Cell Cardiol 2012; 53:687-94. [PMID: 22921807 DOI: 10.1016/j.yjmcc.2012.08.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 07/23/2012] [Accepted: 08/10/2012] [Indexed: 12/16/2022]
Abstract
Freshly isolated adult rabbit sinoatrial node cells (f-SANC) are an excellent model for studies of autonomic signaling, but are not amenable to genetic manipulation. We have developed and characterized a stable cultured rabbit SANC (c-SANC) model that is suitable for genetic manipulation to probe mechanisms of spontaneous action potential (AP) firing. After 48 h in culture, c-SANC generate stable, rhythmic APs at 34±0.5°C, at a rate that is 50% less than f-SANC. In c- vs. f-SANC: AP duration is prolonged; phosphorylation of phospholamban at Ser(16) and type2 ryanodine receptor (RyR2) at Ser(2809) are reduced; and the level of type2 regulator of G-protein signaling (RGS2), that facilitates adenylyl cyclases/cAMP/protein kinase A (PKA) via G(i) inhibition, is substantially reduced. Consistent with the interpretation that cAMP/PKA signaling becomes impaired in c-SANC, acute β-adrenergic receptor stimulation increases phospholamban and RyR2 phosphorylation, enhances RGS2-labeling density, and accelerates the AP firing rate to the similar maximum in c- and f-SANC. Specific PKA inhibition completely inhibits all β-adrenergic receptor effects. Adv-RGS2 infection, or pertussis toxin treatment to disable G(i)-signaling, each partially rescues the c-SANC spontaneous AP firing rate. Thus, a G(i)-dependent reduction in PKA-dependent protein phosphorylation, including that of Ca(2+) cycling proteins, reduces the spontaneous AP firing rate of c-SANC, and can be reversed by genetic or pharmacologic manipulation of PKA signaling.
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Affiliation(s)
- Dongmei Yang
- Laboratory of Cardiovascular Science, IRP, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224-6825, USA
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33
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Park-Windhol C, Zhang P, Zhu M, Su J, Chaves L, Maldonado AE, King ME, Rickey L, Cullen D, Mende U. Gq/11-mediated signaling and hypertrophy in mice with cardiac-specific transgenic expression of regulator of G-protein signaling 2. PLoS One 2012; 7:e40048. [PMID: 22802950 PMCID: PMC3388988 DOI: 10.1371/journal.pone.0040048] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 05/31/2012] [Indexed: 01/19/2023] Open
Abstract
Cardiac hypertrophy is a well-established risk factor for cardiovascular morbidity and mortality. Activation of G(q/11)-mediated signaling is required for pressure overload-induced cardiomyocyte (CM) hypertrophy to develop. We previously showed that among Regulators of G protein Signaling, RGS2 selectively inhibits G(q/11) signaling and its hypertrophic effects in isolated CM. In this study, we generated transgenic mice with CM-specific, conditional RGS2 expression (dTG) to investigate whether RGS2 overexpression can be used to attenuate G(q/11)-mediated signaling and hypertrophy in vivo. Transverse aortic constriction (TAC) induced a comparable rise in ventricular mass and ANF expression and corresponding hemodynamic changes in dTG compared to wild types (WT), regardless of the TAC duration (1-8 wks) and timing of RGS2 expression (from birth or adulthood). Inhibition of endothelin-1-induced G(q/11)-mediated phospholipase C β activity in ventricles and atrial appendages indicated functionality of transgenic RGS2. However, the inhibitory effect of transgenic RGS2 on G(q/11)-mediated PLCβ activation differed between ventricles and atria: (i) in sham-operated dTG mice the magnitude of the inhibitory effect was less pronounced in ventricles than in atria, and (ii) after TAC, negative regulation of G(q/11) signaling was absent in ventricles but fully preserved in atria. Neither difference could be explained by differences in expression levels, including marked RGS2 downregulation after TAC in left ventricle and atrium. Counter-regulatory changes in other G(q/11)-regulating RGS proteins (RGS4, RGS5, RGS6) and random insertion were also excluded as potential causes. Taken together, despite ample evidence for a role of RGS2 in negatively regulating G(q/11) signaling and hypertrophy in CM, CM-specific RGS2 overexpression in transgenic mice in vivo did not lead to attenuate ventricular G(q/11)-mediated signaling and hypertrophy in response to pressure overload. Furthermore, our study suggests chamber-specific differences in the regulation of RGS2 functionality and potential future utility of the new transgenic model in mitigating G(q/11) signaling in the atria in vivo.
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Affiliation(s)
- Cindy Park-Windhol
- Cardiology Division, Cardiovascular Research Center, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, Rhode Island, United States of America
| | - Peng Zhang
- Cardiology Division, Cardiovascular Research Center, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Ming Zhu
- Cardiology Division, Cardiovascular Research Center, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Jialin Su
- Cardiology Division, Cardiovascular Research Center, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Leonard Chaves
- Cardiology Division, Cardiovascular Research Center, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Angel E. Maldonado
- Cardiology Division, Cardiovascular Research Center, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Michelle E. King
- Cardiology Division, Cardiovascular Research Center, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Lisa Rickey
- Cardiology Division, Cardiovascular Research Center, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, Rhode Island, United States of America
| | - Darragh Cullen
- Cardiac Muscle Research Laboratory, Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Ulrike Mende
- Cardiology Division, Cardiovascular Research Center, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
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Jones DL, Tuomi JM, Chidiac P. Role of Cholinergic Innervation and RGS2 in Atrial Arrhythmia. Front Physiol 2012; 3:239. [PMID: 22754542 PMCID: PMC3386567 DOI: 10.3389/fphys.2012.00239] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Accepted: 06/12/2012] [Indexed: 01/25/2023] Open
Abstract
The heart receives sympathetic and parasympathetic efferent innervation as well as the ability to process information internally via an intrinsic cardiac autonomic nervous system (ICANS). For over a century, the role of the parasympathetics via vagal acetylcholine release was related to controlling primarily heart rate. Although in the late 1800s shown to play a role in atrial arrhythmia, the myocardium took precedence from the mid-1950s until in the last decade a resurgence of interest in the autonomics along with signaling cascades, regulators, and ion channels. Originally ignored as being benign and thus untreated, recent emphasis has focused on atrial arrhythmia as atrial fibrillation (AF) is the most common arrhythmia seen by the general practitioner. It is now recognized to have significant mortality and morbidity due to resultant stroke and heart failure. With the aging population, there will be an unprecedented increased burden on health care resources. Although it has been known for more than half a century that cholinergic stimulation can initiate AF, the classical concept focused on the M2 receptor and its signaling cascade including RGS4, as these had been shown to have predominant effects on nodal function (heart rate and conduction block) as well as contractility. However, recent evidence suggests that the M3 receptor may also playa role in initiation and perpetuation of AF and thus RGS2, a putative regulator of the M3 receptor, may be a target for therapeutic intervention. Mice lacking RGS2 (RGS2−/−), were found to have significantly altered electrophysiological atrial responses and were more susceptible to electrically induced AF. Vagally induced or programmed stimulation-induced AF could be blocked by the selective M3R antagonist, darifenacin. These results suggest a potential surgical target (ICANS) and pharmacological targets (M3R, RGS2) for the management of AF.
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Affiliation(s)
- Douglas L Jones
- Department of Physiology and Pharmacology, The University of Western Ontario London, ON, Canada
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Sjögren B, Parra S, Heath LJ, Atkins KB, Xie ZJ, Neubig RR. Cardiotonic steroids stabilize regulator of G protein signaling 2 protein levels. Mol Pharmacol 2012; 82:500-9. [PMID: 22695717 DOI: 10.1124/mol.112.079293] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Regulator of G protein signaling 2 (RGS2), a G(q)-specific GTPase-activating protein, is strongly implicated in cardiovascular function. RGS2(-/-) mice are hypertensive and prone to heart failure, and several rare human mutations that accelerate RGS2 degradation have been identified among patients with hypertension. Therefore, pharmacological up-regulation of RGS2 protein levels might be beneficial. We used a β-galactosidase complementation method to screen several thousand compounds with known pharmacological functions for those that increased RGS2 protein levels. Several cardiotonic steroids (CTSs), including ouabain and digoxin, increased RGS2 but not RGS4 protein levels. CTSs increased RGS2 protein levels through a post-transcriptional mechanism, by slowing protein degradation. RGS2 mRNA levels in primary vascular smooth muscle cells were unaffected by CTS treatment, whereas protein levels were increased 2- to 3-fold. Na(+)/K(+)-ATPase was required for the increase in RGS2 protein levels, because the effect was lost in Na(+)/K(+)-ATPase-knockdown cells. Furthermore, we demonstrated that CTS-induced increases in RGS2 levels were functional and reduced receptor-stimulated, G(q)-dependent, extracellular signal-regulated kinase phosphorylation. Finally, we showed that in vivo treatment with digoxin led to increased RGS2 protein levels in heart and kidney. CTS-induced increases in RGS2 protein levels and function might modify several deleterious mechanisms in hypertension and heart failure. This novel CTS mechanism might contribute to the beneficial actions of low-dose digoxin treatment in heart failure. Our results support the concept of small-molecule modulation of RGS2 protein levels as a new strategy for cardiovascular therapy.
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Affiliation(s)
- Benita Sjögren
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
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36
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Kach J, Sethakorn N, Dulin NO. A finer tuning of G-protein signaling through regulated control of RGS proteins. Am J Physiol Heart Circ Physiol 2012; 303:H19-35. [PMID: 22542620 DOI: 10.1152/ajpheart.00764.2011] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Regulators of G-protein signaling (RGS) proteins are GTPase-activating proteins (GAP) for various Gα subunits of heterotrimeric G proteins. Through this mechanism, RGS proteins regulate the magnitude and duration of G-protein-coupled receptor signaling and are often referred to as fine tuners of G-protein signaling. Increasing evidence suggests that RGS proteins themselves are regulated through multiple mechanisms, which may provide an even finer tuning of G-protein signaling and crosstalk between G-protein-coupled receptors and other signaling pathways. This review summarizes the current data on the control of RGS function through regulated expression, intracellular localization, and covalent modification of RGS proteins, as related to cell function and the pathogenesis of diseases.
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Affiliation(s)
- Jacob Kach
- Department of Medicine, University of Chicago, Illinois, 60637, USA
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37
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Desroches BR, Zhang P, Choi BR, King ME, Maldonado AE, Li W, Rago A, Liu G, Nath N, Hartmann KM, Yang B, Koren G, Morgan JR, Mende U. Functional scaffold-free 3-D cardiac microtissues: a novel model for the investigation of heart cells. Am J Physiol Heart Circ Physiol 2012; 302:H2031-42. [PMID: 22427522 DOI: 10.1152/ajpheart.00743.2011] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
To bridge the gap between two-dimensional cell culture and tissue, various three-dimensional (3-D) cell culture approaches have been developed for the investigation of cardiac myocytes (CMs) and cardiac fibroblasts (CFs). However, several limitations still exist. This study was designed to develop a cardiac 3-D culture model with a scaffold-free technology that can easily and inexpensively generate large numbers of microtissues with cellular distribution and functional behavior similar to cardiac tissue. Using micromolded nonadhesive agarose hydrogels containing 822 concave recesses (800 μm deep × 400 μm wide), we demonstrated that neonatal rat ventricular CMs and CFs alone or in combination self-assembled into viable (Live/Dead stain) spherical-shaped microtissues. Importantly, when seeded simultaneously or sequentially, CMs and CFs self-sorted to be interspersed, reminiscent of their myocardial distribution, as shown by cell type-specific CellTracker or antibody labeling. Microelectrode recordings and optical mapping revealed characteristic triangular action potentials (APs) with a resting membrane potential of -66 ± 7 mV (n = 4) in spontaneously contracting CM microtissues. Under pacing, optically mapped AP duration at 90% repolarization and conduction velocity were 100 ± 30 ms and 18.0 ± 1.9 cm/s, respectively (n = 5 each). The presence of CFs led to a twofold AP prolongation in heterogenous microtissues (CM-to-CF ratio of 1:1). Importantly, Ba(2+)-sensitive inward rectifier K(+) currents and Ca(2+)-handling proteins, including sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a, were detected in CM-containing microtissues. Furthermore, cell type-specific adenoviral gene transfer was achieved, with no impact on microtissue formation or cell viability. In conclusion, we developed a novel scaffold-free cardiac 3-D culture model with several advancements for the investigation of CM and CF function and cross-regulation.
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Affiliation(s)
- B R Desroches
- Cardiovascular Research Center, Cardiology Division, Rhode Island Hospital, Providence, RI 02903, USA
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Xin H, Gu M, Wang WW, Huang SY, Li FP, Cai H, Zhu YZ, Zhang XM. Effects of Leonurine on L-Type Calcium Channel in Rat Ventricular Myocytes. Biol Pharm Bull 2012; 35:1249-56. [DOI: 10.1248/bpb.b12-00011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Hong Xin
- Department of Pharmacology, School of Pharmacy, Fudan University
| | - Ming Gu
- Department of Pharmacology, School of Pharmacy, Fudan University
| | - Wen Wei Wang
- Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University
| | - Shi Ying Huang
- Department of Pharmacology, School of Pharmacy, Fudan University
| | - Fang Ping Li
- Department of Pharmacology, School of Pharmacy, Fudan University
| | - Hui Cai
- Renal Division, Department of Medicine, School of Medicine, Emory University
- Renal Section, Atlanta Veteran Administration Medical Center
| | - Yi Zhun Zhu
- Department of Pharmacology, School of Pharmacy, Fudan University
| | - Xue Mei Zhang
- Department of Pharmacology, School of Pharmacy, Fudan University
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Li Y, Zhang H, Liao W, Song Y, Ma X, Chen C, Lu Z, Li Z, Zhang Y. Transactivated EGFR mediates α1-AR-induced STAT3 activation and cardiac hypertrophy. Am J Physiol Heart Circ Physiol 2011; 301:H1941-51. [DOI: 10.1152/ajpheart.00338.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Li Y, Zhang H, Liao W, Song Y, Ma X, Chen C, Lu Z, Li Z, Zhang Y. α1-Adrenergic receptor (α1-AR) is a crucial mediator of cardiac hypertrophy. Although numerous intracellular pathways have been implicated in α1-AR-induced hypertrophy, its precise mechanism remains elusive. We aimed to determine whether α1-AR induces cardiac hypertrophy through a novel signaling pathway-α1-AR/epidermal growth factor receptor (EGFR)/signal transducer and activator of transcription 3 (STAT3). The activation of STAT3 by α1-AR was first demonstrated by tyrosine phosphorylation, nuclear translocation, DNA binding, and transcriptional activity in neonatal Sprague-Dawley rat cardiomyocytes. Activated STAT3 showed an essential role in α1-AR-induced cardiomyocyte hypertrophic growth, as assessed by treatment with STAT3 inhibitory peptide and lentivirus-STAT3 small interfering RNA. The results were further confirmed by in vivo experiments involving intraperitoneal injection of the STAT3 inhibitor WP1066 significantly inhibiting phenylephrine-infusion-induced heart hypertrophy in male C57BL/6 mice. Furthermore, the α1-AR-activated STAT3 was associated with transactivation of EGFR because inhibition of EGFR with the selective inhibitor AG1478 prevented α1-AR-induced STAT3 tyrosine phosphorylation and its transcriptional activity, as well as cardiac hypertrophy. In summary, these results suggest that α1-AR induces the activation of STAT3, mainly through transactivation of EGFR, which plays an important role in α1-AR-induced cardiac hypertrophy.
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Affiliation(s)
- Yan Li
- Institute of Vascular Medicine, Peking University Third Hospital, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptide, Ministry of Health, and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, People's Republic of China
| | - Hui Zhang
- Institute of Vascular Medicine, Peking University Third Hospital, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptide, Ministry of Health, and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, People's Republic of China
| | - Wenqiang Liao
- Institute of Vascular Medicine, Peking University Third Hospital, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptide, Ministry of Health, and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, People's Republic of China
| | - Yao Song
- Institute of Vascular Medicine, Peking University Third Hospital, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptide, Ministry of Health, and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, People's Republic of China
| | - Xiaowei Ma
- Institute of Vascular Medicine, Peking University Third Hospital, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptide, Ministry of Health, and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, People's Republic of China
| | - Chao Chen
- Institute of Vascular Medicine, Peking University Third Hospital, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptide, Ministry of Health, and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, People's Republic of China
| | - Zhizhen Lu
- Institute of Vascular Medicine, Peking University Third Hospital, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptide, Ministry of Health, and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, People's Republic of China
| | - Zijian Li
- Institute of Vascular Medicine, Peking University Third Hospital, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptide, Ministry of Health, and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, People's Republic of China
| | - Youyi Zhang
- Institute of Vascular Medicine, Peking University Third Hospital, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptide, Ministry of Health, and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, People's Republic of China
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40
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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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41
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Mullick A, Tremblay J, Leon Z, Gros P. A novel role for the fifth component of complement (C5) in cardiac physiology. PLoS One 2011; 6:e22919. [PMID: 21829669 PMCID: PMC3148243 DOI: 10.1371/journal.pone.0022919] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 07/09/2011] [Indexed: 12/17/2022] Open
Abstract
We have previously demonstrated that C5-deficient A/J and recombinant congenic BcA17 mice suffer from cardiac dysfunction when infected with C. albicans blastospores intravenously. During these studies we had observed that, even in the control un-infected state, BcA17 hearts displayed alterations in gene expression that have been associated with pathological cardiac hypertrophy in comparison to parental C5-sufficient C57Bl/6J (B6) mice. Of note was an increase in the expression of Nppb, a member of the fetal gene program and a decrease in the expression of Rgs2, an inhibitor of the hypertrophic response. We now report that C5-deletion has also affected the expression of other elements of the fetal gene program. Moreover deleting the C5a receptor, C5aR, has essentially the same effect as deleting C5, indicating a key role for C5a-C5aR signaling in the phenotype. Having noted a pathological phenotype in the un-infected state, we investigated the role of C5 in the response to cardiac stress. In previous studies, comparison of the expression profiles of C. albicans-infected BcA17 and similarly infected B6 hearts had revealed a paucity of cardioprotective genes in the C5-deficient heart. To determine whether this was also directly linked to C5-deficiency, we tested the expression of 5 such genes in the C. albicans-infected C5aR(-/-) mice. We found again that deletion of C5aR recapitulated the alterations in stress response of BcA17. To determine whether our observations were relevant to other forms of cardiac injury, we tested the effect of C5-deficiency on the response to isoproterenol-induced hypertrophic stimulation. Consistent with our hypothesis, A/J, BcA17 and C5aR(-/-) mice responded with higher levels of Nppa expression than B6 and BALB/c mice. In conclusion, our results suggest that an absence of functional C5a renders the heart in a state of distress, conferring a predisposition to cardiac dysfunction in the face of additional injury.
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Affiliation(s)
- Alaka Mullick
- Biotechnology Research Institute, Montréal, Québec, Canada.
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42
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Zhang P, Su J, King ME, Maldonado AE, Park C, Mende U. Regulator of G protein signaling 2 is a functionally important negative regulator of angiotensin II-induced cardiac fibroblast responses. Am J Physiol Heart Circ Physiol 2011; 301:H147-56. [PMID: 21498776 DOI: 10.1152/ajpheart.00026.2011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cardiac fibroblasts play a key role in fibrosis development in response to stress and injury. Angiotensin II (ANG II) is a major profibrotic activator whose downstream effects (such as phospholipase Cβ activation, cell proliferation, and extracellular matrix secretion) are mainly mediated via G(q)-coupled AT(1) receptors. Regulators of G protein signaling (RGS), which accelerate termination of G protein signaling, are expressed in the myocardium. Among them, RGS2 has emerged as an important player in modulating G(q)-mediated hypertrophic remodeling in cardiac myocytes. To date, no information is available on RGS in cardiac fibroblasts. We tested the hypothesis that RGS2 is an important regulator of ANG II-induced signaling and function in ventricular fibroblasts. Using an in vitro model of fibroblast activation, we have demonstrated expression of several RGS isoforms, among which only RGS2 was transiently upregulated after short-term ANG II stimulation. Similar results were obtained in fibroblasts isolated from rat hearts after in vivo ANG II infusion via minipumps for 1 day. In contrast, prolonged ANG II stimulation (3-14 days) markedly downregulated RGS2 in vivo. To delineate the functional effects of RGS expression changes, we used gain- and loss-of-function approaches. Adenovirally infected RGS2 had a negative regulatory effect on ANG II-induced phospholipase Cβ activity, cell proliferation, and total collagen production, whereas RNA interference of endogenous RGS2 had opposite effects, despite the presence of several other RGS. Together, these data suggest that RGS2 is a functionally important negative regulator of ANG II-induced cardiac fibroblast responses that may play a role in ANG II-induced fibrosis development.
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Affiliation(s)
- Peng Zhang
- Cardiovascular Research Center, Rhode Island Hospital and Alpert Medical School of Brown Univ., 1 Hoppin St., Providence, RI 02903, USA.
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43
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Nunn C, Zhao P, Zou MX, Summers K, Guglielmo CG, Chidiac P. Resistance to age-related, normal body weight gain in RGS2 deficient mice. Cell Signal 2011; 23:1375-86. [PMID: 21447383 DOI: 10.1016/j.cellsig.2011.03.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2010] [Revised: 03/01/2011] [Accepted: 03/21/2011] [Indexed: 01/09/2023]
Abstract
RGS2 (regulator of G protein signaling 2) is known to limit signals mediated via Gq- and Gs-coupled GPCRs (G protein coupled receptors), and it has been implicated in the differentiation of several cells types. The physiology of RGS2 knockout mice (rgs2(-/-)) has been studied in some detail, however, a metabolic phenotype has not previously been reported. We observed that old (21-24month) rgs2(-/-) mice weigh much less than wild-type C57BL/6 controls, and exhibit greatly reduced fat deposits, decreased serum lipids, and low leptin levels. Lower weight was evident as early as four weeks and continued throughout life. Younger adult male rgs2(-/-) mice (4-8months) were found to show similar strain-related differences as the aged animals, as well improved glucose clearance and insulin sensitivity, and enhanced beta-adrenergic and glucagon signaling in isolated hepatocytes. In addition, rgs2(-/-) pre-adipocytes had reduced levels of differentiation markers (Peroxisome proliferator-activated receptor γ (PPARγ); lipoprotein lipase (Lpl); CCAAT/enhancer binding protein α (CEBPα)) and also rgs2(-/-) white adipocytes were small relative to controls, suggesting altered adipogenesis. In wild-type animals, RGS2 mRNA was decreased in brown adipose tissue after cold exposure (7 h at 4 °C) but increased in white adipose tissue in response to a high fat diet, also suggesting a role in lipid storage. No differences between strains were detected with respect to food intake, energy expenditure, GPCR-stimulated lipolysis, or adaptive thermogenesis. In conclusion this study points to RGS2 as being an important regulatory factor in controlling body weight and adipose function.
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Affiliation(s)
- Caroline Nunn
- Department of Physiology and Pharmacology, University of Western Ontario, London, Canada
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44
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Association of intima-media thickening of carotid artery with genetic polymorphisms of the regulator of G-protein signaling 2 gene in patients with hypertension and in the general population. Hypertens Res 2011; 34:740-6. [DOI: 10.1038/hr.2011.25] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Fassett JT, Hu X, Xu X, Lu Z, Zhang P, Chen Y, Bache RJ. Adenosine kinase regulation of cardiomyocyte hypertrophy. Am J Physiol Heart Circ Physiol 2011; 300:H1722-32. [PMID: 21335462 DOI: 10.1152/ajpheart.00684.2010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There is evidence that extracellular adenosine can attenuate cardiac hypertrophy, but the mechanism by which this occurs is not clear. Here we investigated the role of adenosine receptors and adenosine metabolism in attenuation of cardiomyocyte hypertrophy. Phenylephrine (PE) caused hypertrophy of neonatal rat cardiomyocytes with increases of cell surface area, protein synthesis, and atrial natriuretic peptide (ANP) expression. These responses were attenuated by 5 μM 2-chloroadenosine (CADO; adenosine deaminase resistant adenosine analog) or 10 μM adenosine. While antagonism of adenosine receptors partially blocked the reduction of ANP expression produced by CADO, it did not restore cell size or protein synthesis. In support of a role for intracellular adenosine metabolism in regulating hypertrophy, the adenosine kinase (AK) inhibitors iodotubercidin and ABT-702 completely reversed the attenuation of cell size, protein synthesis, and expression of ANP by CADO or ADO. Examination of PE-induced phosphosignaling pathways revealed that CADO treatment did not reduce AKT(Ser⁴⁷³) phosphorylation but did attenuate sustained phosphorylation of Raf(Ser³³⁸) (24-48 h), mTOR(Ser²⁴⁴⁸) (24-48 h), p70S6k(Thr³⁸⁹) (2.5-48 h), and ERK(Thr²⁰²/Tyr²⁰⁴) (48 h). Inhibition of AK restored activation of these enzymes in the presence of CADO. Using dominant negative and constitutively active Raf adenoviruses, we found that Raf activation is necessary and sufficient for PE-induced mTORC1 signaling and cardiomyocyte hypertrophy. CADO treatment still blocked p70S6k(Thr³⁸⁹) phosphorylation and hypertrophy downstream of constitutively active Raf, however, despite a high level phosphorylation of ERK(Thr202/Tyr204) and AKT(Ser⁴⁷³). Reduction of Raf-induced p70S6k(Thr³⁸⁹) phosphorylation and hypertrophy by CADO was reversed by inhibiting AK. Together, these results identify AK as an important mediator of adenosine attenuation of cardiomyocyte hypertrophy, which acts, at least in part, through inhibition of Raf signaling to mTOR/p70S6k.
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Affiliation(s)
- John T Fassett
- Univ. of Minnesota, Mayo Mail Code 508, 401 Delaware St. SE, Minneapolis, MN55455 .
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46
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Chakir K, Zhu W, Tsang S, Woo AYH, Yang D, Wang X, Zeng X, Rhee MH, Mende U, Koitabashi N, Takimoto E, Blumer KJ, Lakatta EG, Kass DA, Xiao RP. RGS2 is a primary terminator of β₂-adrenergic receptor-mediated G(i) signaling. J Mol Cell Cardiol 2011; 50:1000-7. [PMID: 21291891 DOI: 10.1016/j.yjmcc.2011.01.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 01/23/2011] [Accepted: 01/24/2011] [Indexed: 01/08/2023]
Abstract
Two major β-adrenergic receptor (βAR) subtypes, β(1)AR and β(2)AR, are expressed in mammalian heart with β(1)AR coupling to G(s) and β(2)AR dually coupling to G(s) and G(i) proteins. In many types of chronic heart failure, myocardial contractile response to both β(1)AR and β(2)AR stimulation is severely impaired. The dysfunction of βAR signaling in failing hearts is largely attributable to an increase in G(i) signaling, because disruption of the G(i) signaling restores myocardial contractile response to β(1)AR as well as β(2)AR stimulation. However, the mechanism terminating the β(2)AR-G(i) signaling remains elusive, while it has been shown activation of the G(i) signaling is dependent on agonist stimulation and subsequent PKA-mediated phosphorylation of the receptor. Here we demonstrate that regulator of G protein signaling 2 (RGS2) is a primary terminator of the β(2)AR-G(i) signaling. Specifically, prolonged absence of agonist stimulation for 24h impairs the β(2)AR-G(i) signaling, resulting in enhanced β(2)AR- but not β(1)AR-mediated contractile response in cultured adult mouse cardiomyocytes. Increased β(2)AR contractile response is accompanied by a selective upregulation of RGS2 in the absence of alterations in other major cardiac RGS proteins (RGS3-5) or G(s), G(i) or βAR subtypes. Administration of a βAR agonist, isoproterenol (ISO, 1.0 nM), prevents RGS2 upregulation and restores the β(2)AR-G(i) signaling in cultured cells. Furthermore, RGS2 ablation, similar to βAR agonist stimulation, sustains the β(2)AR-G(i) signaling in cultured cells, whereas adenoviral overexpression of RGS2 suppresses agonist-activated β(2)AR-G(i) signaling in cardiomyocytes and HEK293 cells. These findings not only define RGS2 as a novel negative regulator of the β(2)AR-G(i) signaling but also provide a potential novel target for the treatment of chronic heart failure.
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Affiliation(s)
- Khalid Chakir
- Laboratory of Cardiovascular Science, Gerontology Research Center, National Institute on Aging, NIH, Baltimore, MD 21224, USA
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Zhu W, Woo AYH, Zhang Y, Cao CM, Xiao RP. β-adrenergic receptor subtype signaling in the heart: from bench to the bedside. CURRENT TOPICS IN MEMBRANES 2011; 67:191-204. [PMID: 21771491 DOI: 10.1016/b978-0-12-384921-2.00009-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Weizhong Zhu
- Center for Translational Medicine, Thomas Jefferson University, Philadelphia, PA, USA
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48
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Grubb DR, Iliades P, Cooley N, Yu YL, Luo J, Filtz TM, Woodcock EA. Phospholipase Cbeta1b associates with a Shank3 complex at the cardiac sarcolemma. FASEB J 2010; 25:1040-7. [PMID: 21148417 DOI: 10.1096/fj.10-171470] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Activation of the heterotrimeric G protein Gq causes cardiomyocyte hypertrophy in vivo and in cell models. Our previous studies have shown that responses to activated Gq in cardiomyocytes are mediated exclusively by phospholipase Cβ1b (PLCβ1b), because only this PLCβ subtype localizes at the cardiac sarcolemma. In the current study, we investigated the proteins involved in targeting PLCβ1b to the sarcolemma in neonatal rat cardiomyocytes. PLCβ1b, but not PLCβ1a, coimmunoprecipitated with the high-MW scaffolding protein SH3 and ankyrin repeat protein 3 (Shank3), as well as the known Shank3-interacting protein α-fodrin. The 32-aa splice-variant-specific C-terminal tail of PLCβ1b also associated with Shank3 and α-fodrin, indicating that PLCβ1b binds via the C-terminal sequence. Shank3 colocalized with PLCβ1b at the sarcolemma, and both proteins were enriched in the light membrane fractions. Knockdown of Shank3 using siRNA reduced PLC activation and downstream hypertrophic responses, demonstrating the importance of sarcolemmal localization for PLC signaling. These data indicate that PLCβ1b associates with a Shank3 complex at the cardiac sarcolemma via its splice-variant-specific C-terminal tail. Sarcolemmmal localization is central to PLC activation and subsequent downstream signaling following Gq-coupled receptor activation.
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Affiliation(s)
- David R Grubb
- Baker International Diabetes Institute, 75 Commercial Road, Melbourne, 3004, VIC, Australia
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Sjögren B, Neubig RR. Thinking outside of the "RGS box": new approaches to therapeutic targeting of regulators of G protein signaling. Mol Pharmacol 2010; 78:550-7. [PMID: 20664002 PMCID: PMC2981398 DOI: 10.1124/mol.110.065219] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Accepted: 07/22/2010] [Indexed: 11/22/2022] Open
Abstract
Regulators of G protein signaling (RGS) proteins are emerging as potentially important drug targets. The mammalian RGS protein family has more than 20 members and they share a common ∼120-residue RGS homology domain or "RGS box." RGS proteins regulate signaling via G protein-coupled receptors by accelerating GTPase activity at active α subunits of G proteins of the G(q) and G(i/o) families. Most studies searching for modulators of RGS protein function have been focused on inhibiting the GTPase accelerating protein activity. However, many RGS proteins contain additional domains that serve other functions, such as interactions with proteins or subcellular targeting. Here, we discuss a rationale for therapeutic targeting of RGS proteins by regulation of expression or allosteric modulation to permit either increases or decreases in RGS function. Several RGS proteins have reduced expression or function in pathophysiological states, so strategies to increase RGS function would be useful. Because several RGS proteins are rapidly degraded by the N-end rule pathway, finding ways to stabilize them may prove to be an effective way to enhance RGS protein function.
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Affiliation(s)
- Benita Sjögren
- Department of Pharmacology, University of Michigan, 1150 W Medical Center Dr, MSRB III, Ann Arbor, MI 48109, USA
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RGS2 inhibits beta-adrenergic receptor-induced cardiomyocyte hypertrophy. Cell Signal 2010; 22:1231-9. [PMID: 20362664 DOI: 10.1016/j.cellsig.2010.03.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 02/26/2010] [Accepted: 03/25/2010] [Indexed: 11/21/2022]
Abstract
The chronic stimulation of certain G protein-coupled receptors promotes cardiomyocyte hypertrophy and thus plays a pivotal role in the development of human heart failure. The beta-adrenergic receptors (beta-AR) are unique among these in that they signal via Gs, whereas others, such as the alpha1-adrenergic (alpha1-AR) and endothelin-1 (ET-1) receptors, predominantly act through Gq. In this study, we investigated the potential role of regulator of G protein signalling 2 (RGS2) in modulating the hypertrophic effects of the beta-AR agonist isoproterenol (ISO) in rat neonatal ventricular cardiomyocytes. We found that ISO-induced hypertrophy in rat neonatal ventricular myocytes was accompanied by the selective upregulation of RGS2 mRNA, with little or no change in RGS1, RGS3, RGS4 or RGS5. The adenylyl cyclase activator forskolin had a similar effect suggesting that it was mediated through cAMP production. To study the role of RGS2 upregulation in beta-AR-dependent hypertrophy, cardiomyocytes were infected with adenovirus encoding RGS2 and assayed for cell growth, markers of hypertrophy, and beta-AR signalling. ISO-induced increases in cell surface area were virtually eliminated by the overexpression of RGS2, as were increases in alpha-skeletal actin and atrial natriuretic peptide. RGS2 overexpression also significantly attenuated ISO-induced extracellular signal-regulated kinases 1 and 2 (ERK1/2) and Akt activation, which may account for, or contribute to, its observed antihypertrophic effects. In contrast, RGS2 overexpression significantly activated JNK MAP kinase, while decreasing the potency but not the maximal effect of ISO on cAMP accumulation. In conclusion, the present results suggest that RGS2 negatively regulates hypertrophy induced by beta-AR activation and thus may play a protective role in cardiac hypertrophy.
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