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Brand T, Lukannek AK, Jahns V, Jahns R, Lorenz K. From "contraindicated" to "first line" - Current mechanistic insights beyond canonical β-receptor signaling. Curr Opin Pharmacol 2024; 76:102458. [PMID: 38636195 DOI: 10.1016/j.coph.2024.102458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 03/27/2024] [Indexed: 04/20/2024]
Abstract
β-blockers are a solid pillar in the treatment of cardiovascular diseases. However, they are highly discussed regarding effectiveness for certain indications and side-effects. Even though there are up to 20 licensed compounds, only four are used for heart failure (HF) therapy. On the receptor level several key characteristics seem to influence the clinical outcome: subtype selectivity, antagonistic vs (inverse/biased) agonistic properties and -in particular- ancillary capacities. On a molecular level, divergent and novel signaling patterns are being identified and extra-cardiac effects on e.g. inflammation, metabolism and oxidative stress are highlighted. This review discusses different well-known and newly discovered characteristics that need to be considered for HF therapy and in the context of co-morbidities.
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Affiliation(s)
- Theresa Brand
- Institute of Pharmacology and Toxicology, University of Würzburg, Germany
| | | | - Valérie Jahns
- Institute of Pharmacology and Toxicology, University of Würzburg, Germany
| | - Roland Jahns
- Interdisciplinary Bank of Biological Materials and Data Würzburg (ibdw), University Hospital Würzburg, Germany
| | - Kristina Lorenz
- Institute of Pharmacology and Toxicology, University of Würzburg, Germany; Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Cardiovascular Pharmacology, Dortmund, Germany.
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2
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Lefevre TJ, Wei W, Mukhaleva E, Meda Venkata SP, Chandan NR, Abraham S, Li Y, Dessauer CW, Vaidehi N, Smrcka AV. Stabilization of interdomain interactions in G protein α subunits as a determinant of Gα i subtype signaling specificity. J Biol Chem 2024; 300:107211. [PMID: 38522511 PMCID: PMC11066577 DOI: 10.1016/j.jbc.2024.107211] [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: 10/25/2023] [Revised: 03/07/2024] [Accepted: 03/12/2024] [Indexed: 03/26/2024] Open
Abstract
Highly homologous members of the Gαi family, Gαi1-3, have distinct tissue distributions and physiological functions, yet their biochemical and functional properties are very similar. We recently identified PDZ-RhoGEF (PRG) as a novel Gαi1 effector that is poorly activated by Gαi2. In a proteomic proximity labeling screen we observed a strong preference for Gαi1 relative to Gαi2 with respect to engagement of a broad range of potential targets. We investigated the mechanistic basis for this selectivity using PRG as a representative target. Substitution of either the helical domain (HD) from Gαi1 into Gαi2 or substitution of a single amino acid, A230 in Gαi2 with the corresponding D in Gαi1, largely rescues PRG activation and interactions with other potential Gαi targets. Molecular dynamics simulations combined with Bayesian network models revealed that in the GTP bound state, separation at the HD-Ras-like domain (RLD) interface is more pronounced in Gαi2 than Gαi1. Mutation of A230 to D in Gαi2 stabilizes HD-RLD interactions via ionic interactions with R145 in the HD which in turn modify the conformation of Switch III. These data support a model where D229 in Gαi1 interacts with R144 and stabilizes a network of interactions between HD and RLD to promote protein target recognition. The corresponding A230 in Gαi2 is unable to stabilize this network leading to an overall lower efficacy with respect to target interactions. This study reveals distinct mechanistic properties that could underly differential biological and physiological consequences of activation of Gαi1 or Gαi2 by G protein-coupled receptors.
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Affiliation(s)
- Tyler J Lefevre
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA; Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Wenyuan Wei
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, California, USA
| | - Elizaveta Mukhaleva
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, California, USA
| | | | - Naincy R Chandan
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA; Genentech, South San Francisco, California, USA
| | - Saji Abraham
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Yong Li
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, Texas, USA
| | - Carmen W Dessauer
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, Texas, USA
| | - Nagarajan Vaidehi
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, California, USA
| | - Alan V Smrcka
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
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3
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Schröper T, Mehrkens D, Leiss V, Tellkamp F, Engelhardt S, Herzig S, Birnbaumer L, Nürnberg B, Matthes J. Protective effects of Gα i3 deficiency in a murine heart-failure model of β 1-adrenoceptor overexpression. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024; 397:2401-2420. [PMID: 37843590 PMCID: PMC10933181 DOI: 10.1007/s00210-023-02751-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 09/26/2023] [Indexed: 10/17/2023]
Abstract
We have shown that in murine cardiomyopathy caused by overexpression of the β1-adrenoceptor, Gαi2-deficiency is detrimental. Given the growing evidence for isoform-specific Gαi-functions, we now examined the consequences of Gαi3 deficiency in the same heart-failure model. Mice overexpressing cardiac β1-adrenoceptors with (β1-tg) or without Gαi3-expression (β1-tg/Gαi3-/-) were compared to C57BL/6 wildtypes and global Gαi3-knockouts (Gαi3-/-). The life span of β1-tg mice was significantly shortened but improved when Gαi3 was lacking (95% CI: 592-655 vs. 644-747 days). At 300 days of age, left-ventricular function and survival rate were similar in all groups. At 550 days of age, β1-tg but not β1-tg/Gαi3-/- mice displayed impaired ejection fraction (35 ± 18% vs. 52 ± 16%) compared to wildtype (59 ± 4%) and Gαi3-/- mice (60 ± 5%). Diastolic dysfunction of β1-tg mice was prevented by Gαi3 deficiency, too. The increase of ANP mRNA levels and ventricular fibrosis observed in β1-tg hearts was significantly attenuated in β1-tg/Gαi3-/- mice. Transcript levels of phospholamban, ryanodine receptor 2, and cardiac troponin I were similar in all groups. However, Western blots and phospho-proteomic analyses showed that in β1-tg, but not β1-tg/Gαi3-/- ventricles, phospholamban protein was reduced while its phosphorylation increased. Here, we show that in mice overexpressing the cardiac β1-adrenoceptor, Gαi3 deficiency slows or even prevents cardiomyopathy and increases shortened life span. Previously, we found Gαi2 deficiency to aggravate cardiac dysfunction and mortality in the same heart-failure model. Our findings indicate isoform-specific interventions into Gi-dependent signaling to be promising cardio-protective strategies.
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Affiliation(s)
- Tobias Schröper
- Center of Pharmacology, Department II, University of Cologne and University Hospital Cologne, Cologne, Germany
- Department of Internal Medicine III, University Hospital of Cologne, Cologne, Germany and Centre for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Dennis Mehrkens
- Department of Internal Medicine III, University Hospital of Cologne, Cologne, Germany and Centre for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
- Centre for Molecular Medicine Cologne, CMMC, University of Cologne, Cologne, Germany
| | - Veronika Leiss
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute for Experimental and Clinical Pharmacology and Pharmacogenomics, and Interfaculty Centre for Pharmacogenomics and Drug Research, Eberhard Karls Universität, Tübingen, Germany
| | - Frederik Tellkamp
- CECAD Research Centre Institute for Genetics, University of Cologne, Cologne, Germany
| | - Stefan Engelhardt
- Institute of Pharmacology and Toxicology, Technische Universität München, Munich, Germany
| | - Stefan Herzig
- Center of Pharmacology, Department II, University of Cologne and University Hospital Cologne, Cologne, Germany
- TH Köln-University of Applied Sciences, Cologne, Germany
| | - Lutz Birnbaumer
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Research Triangle Park, Durham, North Carolina, USA
- Institute of Biomedical Research, School of Medical Sciences, Catholic University of Buenos Aires, Buenos Aires, Argentina
| | - Bernd Nürnberg
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute for Experimental and Clinical Pharmacology and Pharmacogenomics, and Interfaculty Centre for Pharmacogenomics and Drug Research, Eberhard Karls Universität, Tübingen, Germany
| | - Jan Matthes
- Center of Pharmacology, Department II, University of Cologne and University Hospital Cologne, Cologne, Germany.
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4
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Lefevre TJ, Wei W, Mukhaleva E, Venkata SPM, Chandan NR, Abraham S, Li Y, Dessauer CW, Vaidehi N, Smrcka AV. Stabilization of Interdomain Interactions in G protein α i Subunits Determines Gα i Subtype Signaling Specificity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.10.532072. [PMID: 37066214 PMCID: PMC10103935 DOI: 10.1101/2023.03.10.532072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Highly homologous members of the Gαi family, Gαi1-3, have distinct tissue distributions and physiological functions, yet the functional properties of these proteins with respect to GDP/GTP binding and regulation of adenylate cyclase are very similar. We recently identified PDZ-RhoGEF (PRG) as a novel Gαi1 effector, however, it is poorly activated by Gαi2. Here, in a proteomic proximity labeling screen we observed a strong preference for Gαi1 relative to Gαi2 with respect to engagement of a broad range of potential targets. We investigated the mechanistic basis for this selectivity using PRG as a representative target. Substitution of either the helical domain (HD) from Gαi1 into Gαi2 or substitution of a single amino acid, A230 in Gαi2 to the corresponding D in Gαi1, largely rescues PRG activation and interactions with other Gαi targets. Molecular dynamics simulations combined with Bayesian network models revealed that in the GTP bound state, dynamic separation at the HD-Ras-like domain (RLD) interface is prevalent in Gαi2 relative to Gαi1 and that mutation of A230s4h3.3 to D in Gαi2 stabilizes HD-RLD interactions through formation of an ionic interaction with R145HD.11 in the HD. These interactions in turn modify the conformation of Switch III. These data support a model where D229s4h3.3 in Gαi1 interacts with R144HD.11 stabilizes a network of interactions between HD and RLD to promote protein target recognition. The corresponding A230 in Gαi2 is unable to form the "ionic lock" to stabilize this network leading to an overall lower efficacy with respect to target interactions. This study reveals distinct mechanistic properties that could underly differential biological and physiological consequences of activation of Gαi1 or Gαi2 by GPCRs.
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Affiliation(s)
- Tyler J. Lefevre
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
- Program in Chemical Biology, University of Michigan, Ann Arbor, MI
| | - Wenyuan Wei
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, TX
| | - Elizaveta Mukhaleva
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, TX
| | | | - Naincy R. Chandan
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
- Genentech, South San Francisco, CA
| | - Saji Abraham
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
| | - Yong Li
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, TX
| | - Carmen W. Dessauer
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, TX
| | - Nagarajan Vaidehi
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, CA
| | - Alan V. Smrcka
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
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Kong L, Fang Y, Du M, Wang Y, He H, Liu Z. Gαi2 regulates the adult myogenesis of masticatory muscle satellite cells. J Cell Mol Med 2023; 27:1239-1249. [PMID: 36977201 PMCID: PMC10148056 DOI: 10.1111/jcmm.17726] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 01/22/2023] [Accepted: 03/08/2023] [Indexed: 03/30/2023] Open
Abstract
Although similar to trunk and limb skeletal muscles, masticatory muscles are believed as unique in both developmental origins and myogenesis. Gαi2 has been demonstrated to promote muscle hypertrophy and muscle satellite cell differentiation in limb muscles. However, the effect of Gαi2 on masticatory muscles is still unexplored. This study aimed to identify the role of Gαi2 in the proliferation and differentiation of masticatory muscle satellite cells, further exploring the metabolic mechanism of masticatory muscles. The proliferation rate, myotube size, fusion index of masticatory muscle satellite cells and Pax7, Myf5, MyoD, Tcf21 and Musculin expressions were significantly decreased by Gαi2 knockdown, while in cells infected with AdV4-Gαi2, the proliferation rate, myotube size, fusion index and Tbx1 expression were significantly increased. Masticatory muscle satellite cells also displayed phenotype transformation as Gαi2 changed. In addition, Gαi2 altered myosin heavy chain (MyHC) isoforms of myotubes with less MyHC-2A expression in siGαi2 group and more MyHC-slow expression in AdV4-Gαi2 group. In conclusion, Gαi2 could positively affect the adult myogenesis of masticatory muscle satellite cells and maintain the superiority of MyHC-slow. Masticatory muscle satellite cells may have their unique Gαi2-regulated myogenic transcriptional networks, although they may share some common characteristics with trunk and limb muscles.
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Affiliation(s)
- Lin Kong
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Yi Fang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, China
- Kunming Medical University School and Hospital of Stomatology, Kunming, China
- Yunnan Key Laboratory of Stomatology, Kunming, China
| | - Mingyuan Du
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, China
- Department of Orthodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Yunlong Wang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, China
- Department of Orthodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Hong He
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, China
- Department of Orthodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Zhijian Liu
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, China
- Department of Orthodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, China
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6
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Jiang H, Galtes D, Wang J, Rockman HA. G protein-coupled receptor signaling: transducers and effectors. Am J Physiol Cell Physiol 2022; 323:C731-C748. [PMID: 35816644 PMCID: PMC9448338 DOI: 10.1152/ajpcell.00210.2022] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/27/2022] [Accepted: 07/10/2022] [Indexed: 01/14/2023]
Abstract
G protein-coupled receptors (GPCRs) are of considerable interest due to their importance in a wide range of physiological functions and in a large number of Food and Drug Administration (FDA)-approved drugs as therapeutic entities. With continued study of their function and mechanism of action, there is a greater understanding of how effector molecules interact with a receptor to initiate downstream effector signaling. This review aims to explore the signaling pathways, dynamic structures, and physiological relevance in the cardiovascular system of the three most important GPCR signaling effectors: heterotrimeric G proteins, GPCR kinases (GRKs), and β-arrestins. We will first summarize their prominent roles in GPCR pharmacology before transitioning into less well-explored areas. As new technologies are developed and applied to studying GPCR structure and their downstream effectors, there is increasing appreciation for the elegance of the regulatory mechanisms that mediate intracellular signaling and function.
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Affiliation(s)
- Haoran Jiang
- Department of Medicine, Duke University Medical Center, Durham, North Carolina
| | - Daniella Galtes
- Department of Medicine, Duke University Medical Center, Durham, North Carolina
| | - Jialu Wang
- Department of Medicine, Duke University Medical Center, Durham, North Carolina
| | - Howard A Rockman
- Department of Medicine, Duke University Medical Center, Durham, North Carolina
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina
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Fan X, Yang G, Kowitz J, Akin I, Zhou X, El-Battrawy I. Takotsubo Syndrome: Translational Implications and Pathomechanisms. Int J Mol Sci 2022; 23:ijms23041951. [PMID: 35216067 PMCID: PMC8875072 DOI: 10.3390/ijms23041951] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 02/04/2022] [Accepted: 02/05/2022] [Indexed: 02/07/2023] Open
Abstract
Takotsubo syndrome (TTS) is identified as an acute severe ventricular systolic dysfunction, which is usually characterized by reversible and transient akinesia of walls of the ventricle in the absence of a significant obstructive coronary artery disease (CAD). Patients present with chest pain, ST-segment elevation or ischemia signs on ECG and increased troponin, similar to myocardial infarction. Currently, the known mechanisms associated with the development of TTS include elevated levels of circulating plasma catecholamines and their metabolites, coronary microvascular dysfunction, sympathetic hyperexcitability, inflammation, estrogen deficiency, spasm of the epicardial coronary vessels, genetic predisposition and thyroidal dysfunction. However, the real etiologic link remains unclear and seems to be multifactorial. Currently, the elusive pathogenesis of TTS and the lack of optimal treatment leads to the necessity of the application of experimental models or platforms for studying TTS. Excessive catecholamines can cause weakened ventricular wall motion at the apex and increased basal motion due to the apicobasal adrenoceptor gradient. The use of beta-blockers does not seem to impact the outcome of TTS patients, suggesting that signaling other than the beta-adrenoceptor-associated pathway is also involved and that the pathogenesis may be more complex than it was expected. Herein, we review the pathophysiological mechanisms related to TTS; preclinical TTS models and platforms such as animal models, human-induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) models and their usefulness for TTS studies, including exploring and improving the understanding of the pathomechanism of the disease. This might be helpful to provide novel insights on the exact pathophysiological mechanisms and may offer more information for experimental and clinical research on TTS.
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Affiliation(s)
- Xuehui Fan
- First Department of Medicine, Medical Faculty Mannheim, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (X.F.); (J.K.); (I.A.)
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Collaborative Innovation Center for Prevention of Cardiovascular Diseases, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China
- DZHK (German Center for Cardiovascular Research), Partner Site, Heidelberg-Mannheim, 68167 Mannheim, Germany
| | - Guoqiang Yang
- Department of Acupuncture and Rehabilitation, the Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou 646000, China;
- Research Unit of Molecular Imaging Probes, Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Jacqueline Kowitz
- First Department of Medicine, Medical Faculty Mannheim, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (X.F.); (J.K.); (I.A.)
| | - Ibrahim Akin
- First Department of Medicine, Medical Faculty Mannheim, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (X.F.); (J.K.); (I.A.)
- DZHK (German Center for Cardiovascular Research), Partner Site, Heidelberg-Mannheim, 68167 Mannheim, Germany
| | - Xiaobo Zhou
- First Department of Medicine, Medical Faculty Mannheim, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (X.F.); (J.K.); (I.A.)
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Collaborative Innovation Center for Prevention of Cardiovascular Diseases, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China
- DZHK (German Center for Cardiovascular Research), Partner Site, Heidelberg-Mannheim, 68167 Mannheim, Germany
- Correspondence: (X.Z.); (I.E.-B.)
| | - Ibrahim El-Battrawy
- First Department of Medicine, Medical Faculty Mannheim, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (X.F.); (J.K.); (I.A.)
- DZHK (German Center for Cardiovascular Research), Partner Site, Heidelberg-Mannheim, 68167 Mannheim, Germany
- Correspondence: (X.Z.); (I.E.-B.)
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8
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Leiss V, Reisinger E, Speidel A, Beer-Hammer S, Nürnberg B. Analyses of Gnai3-iresGFP reporter mice reveal unknown Gα i3 expression sites. Sci Rep 2021; 11:14271. [PMID: 34253772 PMCID: PMC8275620 DOI: 10.1038/s41598-021-93591-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/21/2021] [Indexed: 12/01/2022] Open
Abstract
Inhibitory G proteins (Gi proteins) are highly homologous but play distinct biological roles. However, their isoform-specific detection remains challenging. To facilitate the analysis of Gαi3 expression, we generated a Gnai3- iresGFP reporter mouse line. An internal ribosomal entry site (IRES) was inserted behind the stop-codon of the Gnai3 gene to initiate simultaneous translation of the GFP cDNA together with Gαi3. The expression of GFP was confirmed in spleen and thymus tissue by immunoblot analysis. Importantly, the GFP knock-in (ki) did not alter Gαi3 expression levels in all organs tested including spleen and thymus compared to wild-type littermates. Flow cytometry of thymocytes, splenic and blood cell suspensions revealed significantly higher GFP fluorescence intensities in homozygous ki/ki animals compared to heterozygous mice (+/ki). Using cell-type specific surface markers GFP fluorescence was assigned to B cells, T cells, macrophages and granulocytes from both splenic and blood cells and additionally blood-derived platelets. Moreover, immunofluorescent staining of the inner ear from knock-in mice unraveled GFP expression in sensory and non-sensory cell types, with highest levels in Deiter's cells and in the first row of Hensen's cells in the organ of Corti, indicating a novel site for Gαi3 expression. In summary, the Gnai3- iresGFP reporter mouse represents an ideal tool for precise analyses of Gαi3 expression patterns and sites.
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Affiliation(s)
- Veronika Leiss
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, and ICePhA Mouse Clinic, University of Tübingen, Wilhelmstraße 56, 72074, Tübingen, Germany
| | - Ellen Reisinger
- Department of Otolaryngology-Head and Neck Surgery, Gene Therapy for Hearing Impairment Group, University of Tübingen, Medical Center, Elfriede-Aulhorn-Straße 5, 72076, Tübingen, Germany
| | - Annika Speidel
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, and ICePhA Mouse Clinic, University of Tübingen, Wilhelmstraße 56, 72074, Tübingen, Germany
| | - Sandra Beer-Hammer
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, and ICePhA Mouse Clinic, University of Tübingen, Wilhelmstraße 56, 72074, Tübingen, Germany.
| | - Bernd Nürnberg
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, and ICePhA Mouse Clinic, University of Tübingen, Wilhelmstraße 56, 72074, Tübingen, Germany
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9
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Burghi V, Echeverría EB, Sosa MH, Quiroga DT, Muñoz MC, Davio C, Monczor F, Fernández NC, Dominici FP. Participation of Gα i-Adenylate Cyclase and ERK1/2 in Mas Receptor Signaling Pathways. Front Pharmacol 2019; 10:146. [PMID: 30853914 PMCID: PMC6395383 DOI: 10.3389/fphar.2019.00146] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 02/06/2019] [Indexed: 12/21/2022] Open
Abstract
The MasR receptor (MasR) is an orphan G protein-coupled receptor proposed as a candidate for mediating the angiotensin (Ang)-converting enzyme 2-Ang-(1–7) protective axis of renin-angiotensin system. This receptor has been suggested to participate in several physiological processes including cardio- and reno-protection and regulation of the central nervous system function. Although the knowledge of the signaling mechanisms associated with MasR is essential for therapeutic purposes, these are still poorly understood. Accordingly, in the current study we aimed to characterize the signaling pathways triggered by the MasR. To do that, we measured cAMP and Ca2+ levels in both naïve and MasR transfected cells in basal conditions and upon incubation with putative MasR ligands. Besides, we evaluated activation of ERK1/2 by Ang-(1–7) in MasR transfected cells. Results indicated the existence of a high degree of MasR constitutive activity toward cAMP modulation. This effect was not mediated by the PDZ-binding motif of the MasR but by receptor coupling to Gαi-adenylyl cyclase signaling pathway. Incubation of MasR transfected cells with Ang-(1–7) or the synthetic ligand AVE 0991 amplified MasR negative modulation of cAMP levels. On the other hand, we provided evidence for lack of MasR-associated modulation of Ca2+ levels by Ang-(1–7). Finally, it was determined that the MasR attenuated Ang-(1–7)-induced ERK1/2 phosphorylation mediated by AT1R. We provided further characterization of MasR signaling mechanisms regarding its constitutive activity and response to putative ligands. This information could prove useful to better describe MasR physiological role and development of therapeutic agents that could modulate its action.
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Affiliation(s)
- Valeria Burghi
- Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Emiliana B Echeverría
- Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Máximo H Sosa
- Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Diego T Quiroga
- Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Buenos Aires, Argentina
| | - Marina C Muñoz
- Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Buenos Aires, Argentina
| | - Carlos Davio
- Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Federico Monczor
- Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Natalia C Fernández
- Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Fernando P Dominici
- Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Buenos Aires, Argentina
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Tae HJ, Petrashevskaya N, Kim IH, Park JH, Lee JC, Won MH, Kim YH, Ahn JH, Park J, Choi SY, Jeon YH. G protein, phosphorylated-GATA4 and VEGF expression in the hearts of transgenic mice overexpressing β1- and β2-adrenergic receptors. Mol Med Rep 2017; 15:4049-4054. [PMID: 28487987 PMCID: PMC5436146 DOI: 10.3892/mmr.2017.6526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 02/22/2017] [Indexed: 11/27/2022] Open
Abstract
β1- and β2-adrenergic receptors (ARs) regulate cardiac contractility, calcium handling and protein phosphorylation. The present study aimed to examine the expression levels of vascular endothelial growth factor A (VEGF-A) and several G proteins, and the phosphorylation of transcription factor GATA binding protein 4 (GATA4), by western blot analysis, using isolated hearts from 6 month-old transgenic (TG) mice that overexpress β1AR or β2AR. Cardiac contractility/relaxation and heart rate was increased in both β1AR TG and β2AR TG mouse hearts compared with wild type; however, no significant differences were observed between the β1- and β2AR TG mouse hearts. Protein expression levels of inhibitory guanine nucleotide-binding protein (Gi) 2, Gi3 and G-protein-coupled receptor kinase 2 were upregulated in both TG mice, although the upregulation of Gi2 was more prominent in the β2AR TG mice. VEGF-A expression levels were also increased in both TG mice, and were highest in the β1AR TG mice. In addition, the levels of phosphorylated-GATA4 expression were increased in β1- and β2AR TG mice. In conclusion, the present study demonstrated that cardiac contractility/relaxation and heart rate is increased in β1AR TG and β2AR TG mice, and indicated that this increase may be related to the overexpression of G proteins and G-protein-associated proteins.
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Affiliation(s)
- Hyun-Jin Tae
- Bio‑Safety Research Institute, College of Veterinary Medicine, Chonbuk National University, Iksan, Jeollabuk 54596, Republic of Korea
| | - Natalia Petrashevskaya
- Cardiopulmonary Genomics Program, Departments of Medicine and Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - In Hye Kim
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Joon Ha Park
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Jae-Chul Lee
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Moo-Ho Won
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Yang Hee Kim
- Department of Surgery, School of Medicine, Kangwon National University, Chuncheon, Gangwon 24289, Republic of Korea
| | - Ji Hyeon Ahn
- Department of Biomedical Science, Research Institute of Bioscience and Biotechnology, Hallym University, Chuncheon, Gangwon 24252, Republic of Korea
| | - Jinseu Park
- Department of Biomedical Science, Research Institute of Bioscience and Biotechnology, Hallym University, Chuncheon, Gangwon 24252, Republic of Korea
| | - Soo Young Choi
- Department of Biomedical Science, Research Institute of Bioscience and Biotechnology, Hallym University, Chuncheon, Gangwon 24252, Republic of Korea
| | - Yong Hwan Jeon
- Department of Radiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon 24289, Republic of Korea
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11
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Kim KE, Tae HJ, Natalia P, Lee JC, Ahn JH, Park JH, Kim IH, Ohk TG, Park CW, Cho JH, Won MH. Cardiac physiologic regulation of sub-type specific adrenergic receptors in transgenic mice overexpressing β 1- and β 2-adrenergic receptors. Clin Exp Emerg Med 2016; 3:175-180. [PMID: 27752636 PMCID: PMC5065340 DOI: 10.15441/ceem.16.141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 04/29/2016] [Accepted: 05/10/2016] [Indexed: 01/28/2023] Open
Abstract
Objective Combination of β1-adrenergic receptor (AR) blockade and β2-AR activation might be a potential novel therapy for treating heart failure. However, use of β-AR agonists and/or antagonists in the clinical setting is controversial because of the lack of information on cardiac inotropic or chronotropic regulation by AR signaling. Methods In this study, we performed hemodynamic evaluation by examining force frequency response (FFR), Frank-Starling relationship, and response to a non-selective β-AR agonist (isoproterenol) in hearts isolated from 6-month-old transgenic (TG) mice overexpressing β1- and β2-ARs (β1- and β2-AR TG mice, respectively). Results Cardiac physiologic consequences of β1- and β2-AR overexpression resulted in similar maximal response to isoproterenol and faster temporary decline of positive inotropic response in β2-AR TG mice. β1-AR TG mice showed a pronounced negative limb of FFR, whereas β2-AR TG mice showed high stimulation frequencies with low contractile depression during FFR. In contrast, Frank-Starling relationship was equally enhanced in both β1- and β2-AR TG mice. Conclusion Hemodynamic evaluation performed in the present showed a difference in β1- and β2-AR signaling, which may be due to the difference in the desensitization of β1- and β2-ARs.
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Affiliation(s)
- Ka Eul Kim
- Department of Biomedical Science, Research Institute of Bioscience and Biotechnology, Hallym University, Chuncheon, Korea
| | - Hyun-Jin Tae
- Department of Emergency Medicine, Kangwon National University School of Medicine, Chuncheon, Korea; Bio-Safety Research Institute, College of Veterinary Medicine, Chonbuk National University, Iksan, Korea
| | - Petrashevskaya Natalia
- CardioPulmonary Genomics Program, Departments of Medicine and Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jae-Chul Lee
- Department of Neurobiology, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Ji Hyeon Ahn
- Department of Neurobiology, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Joon Ha Park
- Department of Neurobiology, Kangwon National University School of Medicine, Chuncheon, Korea
| | - In Hye Kim
- Department of Neurobiology, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Taek Geun Ohk
- Department of Emergency Medicine, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Chan Woo Park
- Department of Emergency Medicine, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Jun Hwi Cho
- Department of Emergency Medicine, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Moo-Ho Won
- Department of Neurobiology, Kangwon National University School of Medicine, Chuncheon, Korea
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12
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Saddic LA, Muehlschlegel JD. Sarco"MiR" friend or foe: a perspective on the mechanisms of doxorubicin-induced cardiomyopathy. ANNALS OF TRANSLATIONAL MEDICINE 2016; 4:203. [PMID: 27294099 DOI: 10.21037/atm.2016.05.30] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Anthracyclines are a class of chemotherapeutics used to treat a variety of human cancers including both solid tumors such as breast, ovarian, and lung, as well as malignancies of the blood including leukemia and lymphoma. Despite being extremely effective anti-cancer agents, the application of these drugs is offset by side effects, most notably cardiotoxicity. Many patients treated with doxorubicin (DOX), one of the most common anthracyclines used in oncology, will develop radiographic signs and/or symptoms of cardiomyopathy. Since more and more patients treated with these drugs are surviving their malignancies and manifesting with heart disease, there is particular interest in understanding the mechanisms of anthracycline-induced injury and developing ways to prevent and treat its most feared complication, heart failure. MicroRNAs (miRNAs) are small noncoding RNAs that regulate the expression of mRNAs. Since miRNAs can regulate many mRNAs in a single network they tend to play a crucial role in the pathogenesis of several diseases, including heart failure. Here we present a perspective on a recent work by Roca-Alonso and colleagues who demonstrate a cardioprotective function of the miR-30 family members following DOX-induced cardiac injury. They provide evidence for direct targeting of these miRNAs on key elements of the β-adrenergic pathway and further show that this interaction regulates cardiac function and apoptosis. These experiments deliver fresh insights into the biology of toxin-induced cardiomyopathy and suggest the potential for novel therapeutic targets.
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Affiliation(s)
- Louis A Saddic
- Department of Anesthesiology, Perioperative, and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, USA
| | - Jochen D Muehlschlegel
- Department of Anesthesiology, Perioperative, and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, USA
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13
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Keller K, Maass M, Dizayee S, Leiss V, Annala S, Köth J, Seemann WK, Müller-Ehmsen J, Mohr K, Nürnberg B, Engelhardt S, Herzig S, Birnbaumer L, Matthes J. Lack of Gαi2 leads to dilative cardiomyopathy and increased mortality in β1-adrenoceptor overexpressing mice. Cardiovasc Res 2015; 108:348-56. [PMID: 26464333 DOI: 10.1093/cvr/cvv235] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 09/28/2015] [Indexed: 01/05/2023] Open
Abstract
AIMS Inhibitory G (Gi) proteins have been proposed to be cardioprotective. We investigated effects of Gαi2 knockout on cardiac function and survival in a murine heart failure model of cardiac β1-adrenoceptor overexpression. METHODS AND RESULTS β1-transgenic mice lacking Gαi2 (β1-tg/Gαi2 (-/-)) were compared with wild-type mice and littermates either overexpressing cardiac β1-adrenoceptors (β1-tg) or lacking Gαi2 (Gαi2 (-/-)). At 300 days, mortality of mice only lacking Gαi2 was already higher compared with wild-type or β1-tg, but similar to β1-tg/Gαi2 (-/-), mice. Beyond 300 days, mortality of β1-tg/Gαi2 (-/-) mice was enhanced compared with all other genotypes (mean survival time: 363 ± 21 days). At 300 days of age, echocardiography revealed similar cardiac function of wild-type, β1-tg, and Gαi2 (-/-) mice, but significant impairment for β1-tg/Gαi2 (-/-) mice (e.g. ejection fraction 14 ± 2 vs. 40 ± 4% in wild-type mice). Significantly increased ventricle-to-body weight ratio (0.71 ± 0.06 vs. 0.48 ± 0.02% in wild-type mice), left ventricular size (length 0.82 ± 0.04 vs. 0.66 ± 0.03 cm in wild types), and atrial natriuretic peptide and brain natriuretic peptide expression (mRNA: 2819 and 495% of wild-type mice, respectively) indicated hypertrophy. Gαi3 was significantly up-regulated in Gαi2 knockout mice (protein compared with wild type: 340 ± 90% in Gαi2 (-/-) and 394 ± 80% in β1-tg/Gαi2 (-/-), respectively). CONCLUSIONS Gαi2 deficiency combined with cardiac β1-adrenoceptor overexpression strongly impaired survival and cardiac function. At 300 days of age, β1-adrenoceptor overexpression alone had not induced cardiac hypertrophy or dysfunction while there was overt cardiomyopathy in mice additionally lacking Gαi2. We propose an enhanced effect of increased β1-adrenergic drive by the lack of protection via Gαi2. Gαi3 up-regulation was not sufficient to compensate for Gαi2 deficiency, suggesting an isoform-specific or a concentration-dependent mechanism.
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Affiliation(s)
- Kirsten Keller
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Martina Maass
- Department of Internal Medicine III, University Hospital of Cologne, Cologne, Germany
| | - Sara Dizayee
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Veronika Leiss
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
| | - Suvi Annala
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Jessica Köth
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Wiebke K Seemann
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | | | - Klaus Mohr
- Pharmacology and Toxicology Section, Institute of Pharmacy, University of Bonn, Bonn, Germany
| | - Bernd Nürnberg
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, Tuebingen, Germany
| | - Stefan Engelhardt
- Institute of Pharmacology and Toxicology, Technische Universität München, Munich, Germany
| | - Stefan Herzig
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
| | - Lutz Birnbaumer
- Laboratory of Neurobiology, NIEHS, NIH (Department of Health and Human Services), Durham, USA
| | - Jan Matthes
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
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14
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Winter K, Zipprich J, Harriman K, Murray EL, Gornbein J, Hammer SJ, Yeganeh N, Adachi K, Cherry JD. Risk Factors Associated With Infant Deaths From Pertussis: A Case-Control Study. Clin Infect Dis 2015; 61:1099-106. [DOI: 10.1093/cid/civ472] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 06/07/2015] [Indexed: 11/13/2022] Open
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Neubig RR. RGS-Insensitive G Proteins as In Vivo Probes of RGS Function. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 133:13-30. [PMID: 26123300 DOI: 10.1016/bs.pmbts.2015.04.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Guanine nucleotide-binding proteins of the inhibitory (Gi/o) class play critical physiological roles and the receptors that activate them are important therapeutic targets (e.g., mu opioid, serotonin 5HT1a, etc.). Gi/o proteins are negatively regulated by regulator of G protein signaling (RGS) proteins. The redundant actions of the 20 different RGS family members have made it difficult to establish their overall physiological role. A unique G protein mutation (G184S in Gαi/o) prevents RGS binding to the Gα subunit and blocks all RGS action at that particular Gα subunit. The robust phenotypes of mice expressing these RGS-insensitive (RGSi) mutant G proteins illustrate the profound action of RGS proteins in cardiovascular, metabolic, and central nervous system functions. Specifically, the enhanced Gαi2 signaling through the RGSi Gαi2(G184S) mutant knock-in mice shows protection against cardiac ischemia/reperfusion injury and potentiation of serotonin-mediated antidepressant actions. In contrast, the RGSi Gαo mutant knock-in produces enhanced mu-opioid receptor-mediated analgesia but also a seizure phenotype. These genetic models provide novel insights into potential therapeutic strategies related to RGS protein inhibitors and/or G protein subtype-biased agonists at particular GPCRs.
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Affiliation(s)
- Richard R Neubig
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, Michigan, USA.
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16
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Pugh SD, MacDougall DA, Agarwal SR, Harvey RD, Porter KE, Calaghan S. Caveolin contributes to the modulation of basal and β-adrenoceptor stimulated function of the adult rat ventricular myocyte by simvastatin: a novel pleiotropic effect. PLoS One 2014; 9:e106905. [PMID: 25211146 PMCID: PMC4161364 DOI: 10.1371/journal.pone.0106905] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 08/10/2014] [Indexed: 12/22/2022] Open
Abstract
The number of people taking statins is increasing across the globe, highlighting the importance of fully understanding statins' effects on the cardiovascular system. The beneficial impact of statins extends well beyond regression of atherosclerosis to include direct effects on tissues of the cardiovascular system ('pleiotropic effects'). Pleiotropic effects on the cardiac myocyte are often overlooked. Here we consider the contribution of the caveolin protein, whose expression and cellular distribution is dependent on cholesterol, to statin effects on the cardiac myocyte. Caveolin is a structural and regulatory component of caveolae, and is a key regulator of cardiac contractile function and adrenergic responsiveness. We employed an experimental model in which inhibition of myocyte HMG CoA reductase could be studied in the absence of paracrine influences from non-myocyte cells. Adult rat ventricular myocytes were treated with 10 µM simvastatin for 2 days. Simvastatin treatment reduced myocyte cholesterol, caveolin 3 and caveolar density. Negative inotropic and positive lusitropic effects (with corresponding changes in [Ca2+]i) were seen in statin-treated cells. Simvastatin significantly potentiated the inotropic response to β2-, but not β1-, adrenoceptor stimulation. Under conditions of β2-adrenoceptor stimulation, phosphorylation of phospholamban at Ser16 and troponin I at Ser23/24 was enhanced with statin treatment. Simvastatin increased NO production without significant effects on eNOS expression or phosphorylation (Ser1177), consistent with the reduced expression of caveolin 3, its constitutive inhibitor. In conclusion, statin treatment can reduce caveolin 3 expression, with functional consequences consistent with the known role of caveolae in the cardiac cell. These data are likely to be of significance, particularly during the early phases of statin treatment, and in patients with heart failure who have altered β-adrenoceptor signalling. In addition, as caveolin is ubiquitously expressed and has myriad tissue-specific functions, the impact of statin-dependent changes in caveolin is likely to have many other functional sequelae.
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Affiliation(s)
- Sara D. Pugh
- School of Biomedical Sciences, University of Leeds, Leeds, West Yorkshire, United Kingdom
| | - David A. MacDougall
- School of Biomedical Sciences, University of Leeds, Leeds, West Yorkshire, United Kingdom
| | - Shailesh R. Agarwal
- Department of Pharmacology, University of Nevada Reno, Reno, Nevada, United States of America
| | - Robert D. Harvey
- Department of Pharmacology, University of Nevada Reno, Reno, Nevada, United States of America
| | - Karen E. Porter
- Division of Cardiovascular and Diabetes Research, University of Leeds, Leeds, West Yorkshire, United Kingdom
| | - Sarah Calaghan
- School of Biomedical Sciences, University of Leeds, Leeds, West Yorkshire, United Kingdom
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17
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Parra S, Huang X, Charbeneau RA, Wade SM, Kaur K, Rorabaugh BR, Neubig RR. Conditional disruption of interactions between Gαi2 and regulator of G protein signaling (RGS) proteins protects the heart from ischemic injury. BMC Pharmacol Toxicol 2014; 15:29. [PMID: 24899231 PMCID: PMC4059092 DOI: 10.1186/2050-6511-15-29] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 05/28/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Regulator of G protein signaling (RGS) proteins suppress G protein coupled receptor signaling by catalyzing the hydrolysis of Gα-bound guanine nucleotide triphosphate. Transgenic mice in which RGS-mediated regulation of Gαi2 is lost (RGS insensitive Gαi2G184S) exhibit beneficial (protection against ischemic injury) and detrimental (enhanced fibrosis) cardiac phenotypes. This mouse model has revealed the physiological significance of RGS/Gαi2 interactions. Previous studies of the Gαi2G184S mutation used mice that express this mutant protein throughout their lives. Thus, it is unclear whether these phenotypes result from chronic or acute Gαi2G184S expression. We addressed this issue by developing mice that conditionally express Gαi2G184S. METHODS Mice that conditionally express RGS insensitive Gαi2G184S were generated using a floxed minigene strategy. Conditional expression of Gαi2G184S was characterized by reverse transcription polymerase chain reaction and by enhancement of agonist-induced inhibition of cAMP production in isolated cardiac fibroblasts. The impact of conditional RGS insensitive Gαi2G184S expression on ischemic injury was assessed by measuring contractile recovery and infarct sizes in isolated hearts subjected to 30 min ischemia and 2 hours reperfusion. RESULTS We demonstrate tamoxifen-dependent expression of Gαi2G184S, enhanced inhibition of cAMP production, and cardioprotection from ischemic injury in hearts conditionally expressing Gαi2G184S. Thus the cardioprotective phenotype previously reported in mice expressing Gαi2G184S does not require embryonic or chronic Gαi2G184S expression. Rather, cardioprotection occurs following acute (days rather than months) expression of Gαi2G184S. CONCLUSIONS These data suggest that RGS proteins might provide new therapeutic targets to protect the heart from ischemic injury. We anticipate that this model will be valuable for understanding the time course (chronic versus acute) and mechanisms of other phenotypic changes that occur following disruption of interactions between Gαi2 and RGS proteins.
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Affiliation(s)
| | | | | | | | | | - Boyd R Rorabaugh
- Department of Pharmaceutical and Biomedical Sciences, Ohio Northern University College of Pharmacy, Ada, OH 45810, USA.
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18
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Cardiac progenitor cells engineered with βARKct have enhanced β-adrenergic tolerance. Mol Ther 2013; 22:178-85. [PMID: 24002692 DOI: 10.1038/mt.2013.200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 08/21/2013] [Indexed: 01/08/2023] Open
Abstract
Stem cell survival and retention in myocardium after injury following adoptive transfer is low. Elevated catecholamine levels coinciding with myocardial injury adversely affect cardiac progenitor cell (CPC) survival. The G protein-coupled receptor kinase 2 (GRK2)-derived inhibitory peptide, βARKct, enhance myocyte contractility, survival, and normalize the neurohormonal axis in failing heart, however salutary effects of βARKct on CPC survival and proliferation are unknown. Herein, we investigated whether the protective effects of βARKct expression seen in the failing heart relate to CPCs. Modified CPCs expressing βARKct enhanced AKT/eNOS signaling through protective β2-adrenergic receptors (β2-ARs). In addition, to the actions of βARKct expression on β2- AR signaling, pharmacologic inhibition of GRK2 also increased β2-AR signaling in nonengineered CPCs (lacking βARKct) but had limited effects in βARKct engineered CPCs providing evidence for the strength of the βARKct in inhibiting GRK2 in these cells. Increased proliferation and metabolic activity were observed in βARKct-engineered CPCs following catecholamine stimulation indicating improved adrenergic tolerance. βARKct modification of CPCs increased survival and proliferation following adoptive transfer in an acute myocardial infarction model concomitant with increased expression of β-AR. Thus, βARKct engineering of CPCs promotes survival and proliferation of injected cells following myocardial infarction, which includes improved β-adrenergic tolerance essential for stem cell survival.
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19
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Fajardo G, Zhao M, Urashima T, Farahani S, Hu DQ, Reddy S, Bernstein D. Deletion of the β2-adrenergic receptor prevents the development of cardiomyopathy in mice. J Mol Cell Cardiol 2013; 63:155-64. [PMID: 23920331 DOI: 10.1016/j.yjmcc.2013.07.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 07/22/2013] [Accepted: 07/27/2013] [Indexed: 01/03/2023]
Abstract
Beta adrenergic receptor (β-AR) subtypes act through diverse signaling cascades to modulate cardiac function and remodeling. Previous in vitro studies suggest that β1-AR signaling is cardiotoxic whereas β2-AR signaling is cardioprotective, and may be the case during ischemia/reperfusion in vivo. The objective of this study was to assess whether β2-ARs also play a cardioprotective role in the pathogenesis of non-ischemic forms of cardiomyopathy. To dissect the role of β1 vs β2-ARs in modulating MLP (Muscle LIM Protein) cardiomyopathy, we crossbred MLP-/- with β1-/- or β2-/- mice. Deletion of the β2-AR improved survival, cardiac function, exercise capacity and myocyte shortening; by contrast haploinsufficency of the β1-AR reduced survival. Pathologic changes in Ca(2+) handling were reversed in the absence of β2-ARs: peak Ca(2+) and SR Ca(2+) were decreased in MLP-/- and β1+/-/MLP-/- but restored in β2-/-MLP-/-. These changes were associated with reversal of alterations in troponin I and phospholamban phosphorylation. Gi inhibition increased peak and baseline Ca(2+), recapitulating changes observed in the β2-/-/MLP-/-. The L-type Ca(2+) blocker verapamil significantly decreased cardiac function in β2-/-MLP-/- vs WT. We next tested if the protective effects of β2-AR ablation were unique to the MLP model using TAC-induced heart failure. Similar to MLP, β2-/- mice demonstrated delayed progression of heart failure with restoration of myocyte shortening and peak Ca(2+) and Ca(2+) release. Deletion of β2-ARs prevents the development of MLP-/- cardiomyopathy via positive modulation of Ca(2+) due to removal of inhibitory Gi signaling and increased phosphorylation of troponin I and phospholamban. Similar effects were seen after TAC. Unlike previous models where β2-ARs were found to be cardioprotective, in these two models, β2-AR signaling appears to be deleterious, potentially through negative regulation of Ca(2+) dynamics.
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Affiliation(s)
- Giovanni Fajardo
- Department of Pediatrics, Stanford University, Stanford, CA, USA
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20
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Khan M, Mohsin S, Avitabile D, Siddiqi S, Nguyen J, Wallach K, Quijada P, McGregor M, Gude N, Alvarez R, Tilley DG, Koch WJ, Sussman MA. β-Adrenergic regulation of cardiac progenitor cell death versus survival and proliferation. Circ Res 2012; 112:476-86. [PMID: 23243208 DOI: 10.1161/circresaha.112.280735] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
RATIONALE Short-term β-adrenergic stimulation promotes contractility in response to stress but is ultimately detrimental in the failing heart because of accrual of cardiomyocyte death. Endogenous cardiac progenitor cell (CPC) activation may partially offset cardiomyocyte losses, but consequences of long-term β-adrenergic drive on CPC survival and proliferation are unknown. OBJECTIVE We sought to determine the relationship between β-adrenergic activity and regulation of CPC function. METHODS AND RESULTS Mouse and human CPCs express only β2 adrenergic receptor (β2-AR) in conjunction with stem cell marker c-kit. Activation of β2-AR signaling promotes proliferation associated with increased AKT, extracellular signal-regulated kinase 1/2, and endothelial NO synthase phosphorylation, upregulation of cyclin D1, and decreased levels of G protein-coupled receptor kinase 2. Conversely, silencing of β2-AR expression or treatment with β2-antagonist ICI 118, 551 impairs CPC proliferation and survival. β1-AR expression in CPC is induced by differentiation stimuli, sensitizing CPC to isoproterenol-induced cell death that is abrogated by metoprolol. Efficacy of β1-AR blockade by metoprolol to increase CPC survival and proliferation was confirmed in vivo by adoptive transfer of CPC into failing mouse myocardium. CONCLUSIONS β-adrenergic stimulation promotes expansion and survival of CPCs through β2-AR, but acquisition of β1-AR on commitment to the myocyte lineage results in loss of CPCs and early myocyte precursors.
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Affiliation(s)
- Mohsin Khan
- San Diego Heart Research Institute, San Diego State University, San Diego, CA 92182, USA
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Wiege K, Ali SR, Gewecke B, Novakovic A, Konrad FM, Pexa K, Beer-Hammer S, Reutershan J, Piekorz RP, Schmidt RE, Nürnberg B, Gessner JE. Gαi2 is the essential Gαi protein in immune complex-induced lung disease. THE JOURNAL OF IMMUNOLOGY 2012; 190:324-33. [PMID: 23225882 DOI: 10.4049/jimmunol.1201398] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Heterotrimeric G proteins of the Gα(i) family have been implicated in signaling pathways regulating cell migration in immune diseases. The Gα(i)-protein-coupled C5a receptor is a critical regulator of IgG FcR function in experimental models of immune complex (IC)-induced inflammation. By using mice deficient for Gα(i2) or Gα(i3), we show that Gα(i2) is necessary for neutrophil influx in skin and lung Arthus reactions and agonist-induced neutrophilia in the peritoneum, whereas Gα(i3) plays a less critical but variable role. Detailed analyses of the pulmonary IC-induced inflammatory response revealed several shared functions of Gα(i2) and Gα(i3), including mediating C5a anaphylatoxin receptor-induced activation of macrophages, involvement in alveolar production of chemokines, transition of neutrophils from bone marrow into blood, and modulation of CD11b and CD62L expression that account for neutrophil adhesion to endothelial cells. Interestingly, C5a-stimulated endothelial polymorphonuclear neutrophil transmigration, but not chemotaxis, is enhanced versus reduced in the absence of neutrophil Gα(i3) or Gα(i2), respectively, and knockdown of endothelial Gα(i2) caused decreased transmigration of wild-type neutrophils. These data demonstrate that Gα(i2) and Gα(i3) contribute to inflammation by redundant, overlapping, and Gα(i)-isoform-specific mechanisms, with Gα(i2) exhibiting unique functions in both neutrophils and endothelial cells that appear essential for polymorphonuclear neutrophil recruitment in IC disease.
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Affiliation(s)
- Kristina Wiege
- Molecular Immunology Research Unit, Clinical Department of Immunology and Rheumatology, Hannover Medical School, 30625 Hannover, Germany
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Paur H, Wright PT, Sikkel MB, Tranter MH, Mansfield C, O'Gara P, Stuckey DJ, Nikolaev VO, Diakonov I, Pannell L, Gong H, Sun H, Peters NS, Petrou M, Zheng Z, Gorelik J, Lyon AR, Harding SE. High levels of circulating epinephrine trigger apical cardiodepression in a β2-adrenergic receptor/Gi-dependent manner: a new model of Takotsubo cardiomyopathy. Circulation 2012; 126:697-706. [PMID: 22732314 DOI: 10.1161/circulationaha.112.111591] [Citation(s) in RCA: 566] [Impact Index Per Article: 47.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Takotsubo cardiomyopathy is an acute heart failure syndrome characterized by myocardial hypocontractility from the mid left ventricle to the apex. It is precipitated by extreme stress and can be triggered by intravenous catecholamine administration, particularly epinephrine. Despite its grave presentation, Takotsubo cardiomyopathy is rapidly reversible, with generally good prognosis. We hypothesized that this represents switching of epinephrine signaling through the pleiotropic β(2)-adrenergic receptor (β(2)AR) from canonical stimulatory G-protein-activated cardiostimulant to inhibitory G-protein-activated cardiodepressant pathways. METHODS AND RESULTS We describe an in vivo rat model in which a high intravenous epinephrine, but not norepinephrine, bolus produces the characteristic reversible apical depression of myocardial contraction coupled with basal hypercontractility. The effect is prevented via G(i) inactivation by pertussis toxin pretreatment. β(2)AR number and functional responses were greater in isolated apical cardiomyocytes than in basal cardiomyocytes, which confirmed the higher apical sensitivity and response to circulating epinephrine. In vitro studies demonstrated high-dose epinephrine can induce direct cardiomyocyte cardiodepression and cardioprotection in a β(2)AR-Gi-dependent manner. Preventing epinephrine-G(i) effects increased mortality in the Takotsubo model, whereas β-blockers that activate β(2)AR-G(i) exacerbated the epinephrine-dependent negative inotropic effects without further deaths. In contrast, levosimendan rescued the acute cardiac dysfunction without increased mortality. CONCLUSIONS We suggest that biased agonism of epinephrine for β(2)AR-G(s) at low concentrations and for G(i) at high concentrations underpins the acute apical cardiodepression observed in Takotsubo cardiomyopathy, with an apical-basal gradient in β(2)ARs explaining the differential regional responses. We suggest this epinephrine-specific β(2)AR-G(i) signaling may have evolved as a cardioprotective strategy to limit catecholamine-induced myocardial toxicity during acute stress.
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Affiliation(s)
- Helen Paur
- Myocardial Function Section, National Heart and Lung Inst, Imperial College London, London, United kingdom
| | - Peter T Wright
- Myocardial Function Section, National Heart and Lung Inst, Imperial College London, London, United kingdom
| | - Markus B Sikkel
- Myocardial Function Section, National Heart and Lung Inst, Imperial College London, London, United kingdom
| | - Matthew H Tranter
- Myocardial Function Section, National Heart and Lung Inst, Imperial College London, London, United kingdom
| | - Catherine Mansfield
- Myocardial Function Section, National Heart and Lung Inst, Imperial College London, London, United kingdom
| | - Peter O'Gara
- Myocardial Function Section, National Heart and Lung Inst, Imperial College London, London, United kingdom
| | - Daniel J Stuckey
- Myocardial Function Section, National Heart and Lung Inst, Imperial College London, London, United kingdom
| | - Viacheslav O Nikolaev
- Emmy Noether Group of the DFG, Dept of Cardiology and Pneumology, Georg August Univ medical Ctr, Göttingn Germany
| | - Ivan Diakonov
- Myocardial Function Section, National Heart and Lung Inst, Imperial College London, London, United kingdom
| | - Laura Pannell
- Myocardial Function Section, National Heart and Lung Inst, Imperial College London, London, United kingdom
| | | | - Hong Sun
- Physiology Dept, Xuzhou Medical College, Xuzhou, China
| | - Nicholas S Peters
- Myocardial Function Section, National Heart and Lung Inst, Imperial College London, London, United kingdom
| | - Mario Petrou
- Cardiovasular Biomedical Rsrch Unit, Royal Brompton Hosp, London, United Kingdom
| | | | - Julia Gorelik
- Myocardial Function Section, National Heart and Lung Inst, Imperial College London, London, United kingdom
| | - Alexander R Lyon
- Myocardial Function Section, National Heart and Lung Inst, Imperial College London, London, United kingdom.,Cardiovasular Biomedical Rsrch Unit, Royal Brompton Hosp, London, United Kingdom
| | - Sian E Harding
- Myocardial Function Section, National Heart and Lung Inst, Imperial College London, London, United kingdom
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Ang R, Opel A, Tinker A. The Role of Inhibitory G Proteins and Regulators of G Protein Signaling in the in vivo Control of Heart Rate and Predisposition to Cardiac Arrhythmias. Front Physiol 2012; 3:96. [PMID: 22783193 PMCID: PMC3390690 DOI: 10.3389/fphys.2012.00096] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 03/27/2012] [Indexed: 12/17/2022] Open
Abstract
Inhibitory heterotrimeric G proteins and the control of heart rate. The activation of cell signaling pathways involving inhibitory heterotrimeric G proteins acts to slow the heart rate via modulation of ion channels. A large number of Regulators of G protein signalings (RGSs) can act as GTPase accelerating proteins to inhibitory G proteins and thus it is important to understand the network of RGS\G-protein interaction. We will review our recent findings on in vivo heart rate control in mice with global genetic deletion of various inhibitory G protein alpha subunits. We will discuss potential central and peripheral contributions to the phenotype and the controversies in the literature.
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Affiliation(s)
- Richard Ang
- Centre for Clinical Pharmacology, Division of Medicine, University College LondonLondon, UK
| | - Aaisha Opel
- Centre for Clinical Pharmacology, Division of Medicine, University College LondonLondon, UK
| | - Andrew Tinker
- William Harvey Heart Centre, Barts and The London School of Medicine and DentistryLondon, UK
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Gαi2 signaling: friend or foe in cardiac injury and heart failure? Naunyn Schmiedebergs Arch Pharmacol 2012; 385:443-53. [PMID: 22411356 DOI: 10.1007/s00210-011-0705-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 10/13/2011] [Indexed: 12/20/2022]
Abstract
Receptors coupled to G proteins have many effects on the heart. Enhanced signaling by Gα(s) and Gα(q) leads to cardiac injury and heart failure, while Gα(i2) signaling in cardiac myocytes can protect against ischemic injury and β-adrenergic-induced heart failure. We asked whether enhanced Gα(i2) signaling in mice could protect against heart failure using a point mutation in Gα(i2) (G184S), which prevents negative regulation by regulators of G protein signaling. Contrary to our expectation, it worsened effects of a genetic dilated cardiomyopathy (DCM) and catecholamine-induced cardiac injury. Gα (i2) (G184S/+) /DCM double heterozygote mice (TG9(+)Gα (i2) (G184S/+)) had substantially decreased survival compared to DCM animals. Furthermore, heart weight/body weight ratios (HW/BW) were significantly greater in TG9(+)Gα (i2) (G184S/+) mice as was expression of natriuretic peptide genes. Catecholamine injury in Gα (i2) (G184S/G184S) mutant mice produced markedly increased isoproterenol-induced fibrosis and collagen III gene expression vs WT mice. Cardiac fibroblasts from Gα (i2) (G184S/G184S) mice also showed a serum-dependent increase in proliferation and ERK phosphorylation, which were blocked by pertussis toxin and a mitogen-activated protein/extracellular signal-regulated kinase kinase inhibitor. Gα(i2) signaling in cardiac myocytes protects against ischemic injury but enhancing Gα(i2) signaling overall may have detrimental effects in heart failure, perhaps through actions on cardiac fibroblasts.
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Gαi2- and Gαi3-specific regulation of voltage-dependent L-type calcium channels in cardiomyocytes. PLoS One 2011; 6:e24979. [PMID: 21966394 PMCID: PMC3180279 DOI: 10.1371/journal.pone.0024979] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 08/23/2011] [Indexed: 11/19/2022] Open
Abstract
Background Two pertussis toxin sensitive Gi proteins, Gi2 and Gi3, are expressed in cardiomyocytes and upregulated in heart failure. It has been proposed that the highly homologous Gi isoforms are functionally distinct. To test for isoform-specific functions of Gi proteins, we examined their role in the regulation of cardiac L-type voltage-dependent calcium channels (L-VDCC). Methods Ventricular tissues and isolated myocytes were obtained from mice with targeted deletion of either Gαi2 (Gαi2−/−) or Gαi3 (Gαi3−/−). mRNA levels of Gαi/o isoforms and L-VDCC subunits were quantified by real-time PCR. Gαi and Cavα1 protein levels as well as protein kinase B/Akt and extracellular signal-regulated kinases 1/2 (ERK1/2) phosphorylation levels were assessed by immunoblot analysis. L-VDCC function was assessed by whole-cell and single-channel current recordings. Results In cardiac tissue from Gαi2−/− mice, Gαi3 mRNA and protein expression was upregulated to 187±21% and 567±59%, respectively. In Gαi3−/− mouse hearts, Gαi2 mRNA (127±5%) and protein (131±10%) levels were slightly enhanced. Interestingly, L-VDCC current density in cardiomyocytes from Gαi2−/− mice was lowered (−7.9±0.6 pA/pF, n = 11, p<0.05) compared to wild-type cells (−10.7±0.5 pA/pF, n = 22), whereas it was increased in myocytes from Gαi3−/− mice (−14.3±0.8 pA/pF, n = 14, p<0.05). Steady-state inactivation was shifted to negative potentials, and recovery kinetics slowed in the absence of Gαi2 (but not of Gαi3) and following treatment with pertussis toxin in Gαi3−/−. The pore forming Cavα1 protein level was unchanged in all mouse models analyzed, similar to mRNA levels of Cavα1 and Cavβ2 subunits. Interestingly, at the cellular signalling level, phosphorylation assays revealed abolished carbachol-triggered activation of ERK1/2 in mice lacking Gαi2. Conclusion Our data provide novel evidence for an isoform-specific modulation of L-VDCC by Gαi proteins. In particular, loss of Gαi2 is reflected by alterations in channel kinetics and likely involves an impairment of the ERK1/2 signalling pathway.
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Two-photon polarization microscopy reveals protein structure and function. Nat Methods 2011; 8:684-90. [PMID: 21725301 DOI: 10.1038/nmeth.1643] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Accepted: 05/17/2011] [Indexed: 11/08/2022]
Abstract
Membrane proteins are a large, diverse group of proteins, serving a multitude of cellular functions. They are difficult to study because of their requirement of a lipid membrane for function. Here we show that two-photon polarization microscopy can take advantage of the cell membrane requirement to yield insights into membrane protein structure and function, in living cells and organisms. The technique allows sensitive imaging of G-protein activation, changes in intracellular calcium concentration and other processes, and is not limited to membrane proteins. Conveniently, many suitable probes for two-photon polarization microscopy already exist.
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Dorn GW. Adrenergic signaling polymorphisms and their impact on cardiovascular disease. Physiol Rev 2010; 90:1013-62. [PMID: 20664078 DOI: 10.1152/physrev.00001.2010] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
This review examines the impact of recent discoveries defining personal genetics of adrenergic signaling polymorphisms on scientific discovery and medical practice related to cardiovascular diseases. The adrenergic system is the major regulator of minute-by-minute cardiovascular function. Inhibition of adrenergic signaling with pharmacological beta-adrenergic receptor antagonists (beta-blockers) is first-line therapy for heart failure and hypertension. Advances in pharmacology, molecular biology, and genetics of adrenergic signaling pathways have brought us to the point where personal genetic differences in adrenergic signaling factors are being assessed as determinants of risk or progression of cardiovascular disease. For a few polymorphisms, functional data generated in cell-based systems, genetic mouse models, and pharmacological provocation of human subjects are concordant with population studies that suggest altered risk of cardiovascular disease or therapeutic response to beta-blockers. For the majority of adrenergic pathway polymorphisms however, published data conflict, and the clinical relevance of individual genotyping remains uncertain. Here, the current state of laboratory and clinical evidence that adrenergic pathway polymorphisms can affect cardiovascular pathophysiology is comprehensively reviewed and compared, with a goal of placing these data in the broad context of potential clinical applicability.
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Affiliation(s)
- Gerald W Dorn
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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Chan TO, Funakoshi H, Song J, Zhang XQ, Wang J, Chung PH, DeGeorge BR, Li X, Zhang J, Herrmann DE, Diamond M, Hamad E, Houser SR, Koch WJ, Cheung JY, Feldman AM. Cardiac-restricted overexpression of the A(2A)-adenosine receptor in FVB mice transiently increases contractile performance and rescues the heart failure phenotype in mice overexpressing the A(1)-adenosine receptor. Clin Transl Sci 2010; 1:126-33. [PMID: 20354569 DOI: 10.1111/j.1752-8062.2008.00027.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In the heart, adenosine binds to pharmacologically distinct G-protein-coupled receptors (A(1)-R, A(2A)-R, and A(3)-R). While the role of A(1)- and A(3)-Rs in the heart has been clarified, the effect of genetically manipulating the A(2A)-R has not been defined. Thus, we created mice overexpressing a cardiac-restricted A(2A)-R transgene. Mice with both low (Lo) and high (Hi) levels of A(2A)-R overexpression demonstrated an increase in cardiac contractility at 12 weeks. These changes were associated with a significantly higher systolic but not diastolic [Ca(2+)]i, higher maximal contraction amplitudes, and a significantly enhanced sarcoplasmic reticulum Ca(2+) uptake activity. At 20 weeks, the effects of A(2A)-R overexpression on cardiac contractility diminished. The positive effects elicited by A(2A)-R overexpression differ from the heart failure phenotype we observed with A(1)-R overexpression. Interestingly, coexpression of A(2A)-R TG(Hi), but not A(2A)-R TGLo, enhanced survival, prevented the development of left ventricular dysfunction and heart failure, and improved Ca(2+) handling in mice overexpressing the A(1)-R. These results suggest that adenosine-mediated signaling in the heart requires a balance between A(1)- and A(2A)-Rs--a finding that may have important implications for the ongoing clinical evaluation of adenosine receptor subtype-specific agonists and antagonists for the treatment of cardiovascular diseases.
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Affiliation(s)
- Tung O Chan
- Center For Translational Medicine, Department of Medicine, Jefferson Medical College, Philadelphia, Pennsylvania, USA
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Zuberi Z, Nobles M, Sebastian S, Dyson A, Lim SY, Breckenridge R, Birnbaumer L, Tinker A. Absence of the inhibitory G-protein Galphai2 predisposes to ventricular cardiac arrhythmia. Circ Arrhythm Electrophysiol 2010; 3:391-400. [PMID: 20495013 DOI: 10.1161/circep.109.894329] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND We explored the role that inhibitory heterotrimeric G-proteins play in ventricular arrhythmia. METHODS AND RESULTS Mice with global genetic deletion of Galpha(i2) [Galpha(i2) (-/-)] were studied and found, based on telemetry, to have a prolonged QT interval on surface ECG when awake. In vivo electrophysiology studies revealed that the Galpha(i2) (-/-) mice have a reduced ventricular effective refractory period and a predisposition to ventricular tachycardia when challenged with programmed electrical stimulation. Neither control nor combined global deletion of Galpha(i1) and Galpha(i3) mice showed these abnormalities. There was no evidence for structural heart disease at this time point in the Galpha(i2) (-/-) mice as assessed by cardiac histology and echocardiography. The absence of Galpha(i2) thus leads to a primary electrical abnormality, and we explored the basis for this finding. With patch clamping, single isolated ventricular cells showed that Galpha(i2) (-/-) mice had a prolonged ventricular action potential duration (APD) but steeper action potential shortening as the diastolic interval was reduced in restitution studies. Gene expression studies showed increased expression of L-type Ca(2+) channel subunits, and patch clamping revealed an increase in these currents in Galpha(i2) (-/-) mice. There were no changes in K(+) currents. CONCLUSIONS The absence of inhibitory G-protein signaling mediated through Galpha(i2) is a substrate for ventricular arrhythmias.
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Affiliation(s)
- Zia Zuberi
- Department of Medicine and Hatter Cardiovascular Institute, University College London, 5 University Street, London, England, UK
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Arioglu E, Guner S, Ozakca I, Altan VM, Ozcelikay AT. The changes in beta-adrenoceptor-mediated cardiac function in experimental hypothyroidism: the possible contribution of cardiac beta3-adrenoceptors. Mol Cell Biochem 2009; 335:59-66. [PMID: 19728039 DOI: 10.1007/s11010-009-0241-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Accepted: 08/13/2009] [Indexed: 12/16/2022]
Abstract
Thyroid hormone deficiency has been reported to decrease expression and function of both beta(1)- and beta(2)-adrenoceptor in different tissues including heart. The purpose of this study was to examine the possible contribution of beta(3)-adrenoceptors to cardiac dysfunction in hypothyroidism. In addition, effect of this pathology on beta(1)- and beta(2)-adrenoceptor was investigated. Hypothyroidism was induced by adding methimazole (300 mg/l) to drinking water of rats for 8 weeks. Cardiac hemodynamic parameters were measured in anesthetised rats in vivo. Responses to beta-adrenoceptor agonists were examined in rat papillary muscle in vitro. We also studied the effect of hypotyroidism on mRNA expression of beta-adrenoceptors, Gialpha, GRK, and eNOS in rat heart. All of the hemodynamic parameters (systolic, diastolic and mean arterial pressure, left ventricular pressure, heart rate, +dp/dt, and -dp/dt) were significantly reduced by the methimazole treatment. The negative inotropic effect elicited by BRL 37344 (a beta(3)-adrenoceptor preferential agonist) and positive inotropic effects produced by isoprenaline and noradrenaline, respectively, were significantly decreased in papillary muscle of hypothyroid rats as compared to those of controls. On the other hand, hypothyroidism resulted in increased cardiac beta(2)- and beta(3)-adrenoceptor, Gialpha(2), Gialpha(3), GRK3, and eNOS mRNA expressions. However, beta(1)-adrenoceptor and GRK2 mRNA expressions were not changed significantly in this pathology. These results show that mRNA expression of beta(3)-adrenoceptors as well as the signalling pathway components mediated through beta(3)-adrenoceptors are significantly increased in hypothyroid rat heart. Since we could not correlate these alternates with the decreased negative inotropic response mediated by this receptor subtype, it is not clear whether these changes are important for hypothyroid induced reduction in cardiac function.
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Affiliation(s)
- E Arioglu
- Department of Pharmacology, Faculty of Pharmacy, Ankara University, 06100 Tandogan, Ankara, Turkey
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Xie L, Xiao K, Whalen EJ, Forrester MT, Freeman RS, Fong G, Gygi SP, Lefkowitz RJ, Stamler JS. Oxygen-regulated beta(2)-adrenergic receptor hydroxylation by EGLN3 and ubiquitylation by pVHL. Sci Signal 2009; 2:ra33. [PMID: 19584355 DOI: 10.1126/scisignal.2000444] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Agonist-induced ubiquitylation and degradation of heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) play an essential role in surface receptor homeostasis, thereby tuning many physiological processes. Although beta-arrestin and affiliated E3 ligases mediate agonist-stimulated lysosomal degradation of the beta(2)-adrenergic receptor (beta(2)AR), a prototypic GPCR, the molecular cues that mark receptors for ubiquitylation and the regulation of receptor degradation by the proteasome remain poorly understood. We show that the von Hippel-Lindau tumor suppressor protein (pVHL)-E3 ligase complex, known for its regulation of hypoxia-inducible factor (HIF) proteins, interacts with and ubiquitylates the beta(2)AR, thereby decreasing receptor abundance. We further show that the interaction of pVHL with beta(2)AR is dependent on proline hydroxylation (proline-382 and -395) and that the dioxygenase EGLN3 interacts directly with the beta(2)AR to serve as an endogenous beta(2)AR prolyl hydroxylase. Under hypoxic conditions, receptor hydroxylation and subsequent ubiquitylation decrease dramatically, thus attenuating receptor degradation and down-regulation. Notably, in both cells and tissue, the abundance of endogenous beta(2)AR is shown to reflect constitutive turnover by EGLN3 and pVHL. Our findings provide insight into GPCR regulation, broaden the functional scope of prolyl hydroxylation, and expand our understanding of the cellular response to hypoxia.
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Affiliation(s)
- Liang Xie
- Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
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Chakir K, Daya SK, Aiba T, Tunin RS, Dimaano VL, Abraham TP, Jaques-Robinson KM, Jacques K, Lai EW, Pacak K, Zhu WZ, Xiao RP, Tomaselli GF, Kass DA. Mechanisms of enhanced beta-adrenergic reserve from cardiac resynchronization therapy. Circulation 2009; 119:1231-40. [PMID: 19237665 DOI: 10.1161/circulationaha.108.774752] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Cardiac resynchronization therapy (CRT) is the first clinical heart failure treatment that improves chamber systolic function in both the short-term and long-term yet also reduces mortality. The mechanical impact of CRT is immediate and well documented, yet its long-term influences on myocyte function and adrenergic modulation that may contribute to its sustained benefits are largely unknown. METHODS AND RESULTS We used a canine model of dyssynchronous heart failure (DHF; left bundle ablation, atrial tachypacing for 6 weeks) and CRT (DHF for 3 weeks, biventricular tachypacing for subsequent 3 weeks), contrasting both to nonfailing controls. CRT restored contractile synchrony and improved systolic function compared with DHF. Myocyte sarcomere shortening and calcium transients were markedly depressed at rest and after isoproterenol stimulation in DHF (both anterior and lateral walls), and CRT substantially improved both. In addition, beta(1) and beta(2) stimulation was enhanced, coupled to increased beta(1) receptor abundance but no change in binding affinity. CRT also augmented adenylate cyclase activity over DHF. Inhibitory G-protein (Galpha(i)) suppression of beta-adrenergic stimulation was greater in DHF and reversed by CRT. Galpha(i) expression itself was unaltered; however, expression of negative regulators of Galpha(i) signaling (particularly RGS3) rose uniquely with CRT over DHF and controls. CRT blunted elevated myocardial catecholamines in DHF, restoring levels toward control. CONCLUSIONS CRT improves rest and beta-adrenergic-stimulated myocyte function and calcium handling, upregulating beta(1) receptors and adenylate cyclase activity and suppressing G(i)-coupled signaling associated with novel RGS upregulation. The result is greater rest and sympathetic reserve despite reduced myocardial neurostimulation as components underlying its net benefit.
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Affiliation(s)
- Khalid Chakir
- Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, MD, USA
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Vacek TP, Sen U, Tyagi N, Vacek JC, Kumar M, Hughes WM, Passmore JC, Tyagi SC. Differential expression of Gs in a murine model of homocysteinemic heart failure. Vasc Health Risk Manag 2009; 5:79-84. [PMID: 19436674 PMCID: PMC2672463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
High plasma homocysteine levels are a known risk factor in heart failure and sudden cardiac death. The G proteins, G(s) (stimulatory) and G(i) (inhibitory), are involved in calcium regulation; overexpression has pathological consequences. The aims of this study were to examine the differential expression of G(s) G protein and G(i) in the hearts of hyperhomocysteinemic (Hhcy) mice, and to determine if homocysteine (Hcy) acts as an agonist in cell culture to mediate the change in G protein isoforms. To create Hhcy, heterozygous cystathionine-beta-synthase (CBS) knockout (KO) mice were used. Mice were sacrificed, hearts were excised, cardiac tissue homogenates were prepared, and Western blots were performed. The results suggested that G(s) G protein was downregulated in cardiac tissue of heterozygous CBS KO mice to 46% that of control hearts. However, the intracellular G(i) G protein content remained the same in heterozygous CBS KO mice. Transformed cardiomyocyte HL-1 cells were treated with varying concentrations of homocysteine. The results suggested no detectable differential G(s) and G(i) expression. This suggested that Hcy did not act as an agonist in vitro to alter G protein content, but that Hcy produced some other in vivo effects to incur these results.
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Affiliation(s)
| | | | - Neetu Tyagi
- Correspondence: Suresh C Tyagi, Department of Physiology and Biophysics, Health Sciences Center, A-1213, University of Louisville, Louisville, KY 40292, USA, Tel +1 502 852 3381, Fax +1 502 852 6239, Email
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Ryall JG, Lynch GS. The potential and the pitfalls of β-adrenoceptor agonists for the management of skeletal muscle wasting. Pharmacol Ther 2008; 120:219-32. [DOI: 10.1016/j.pharmthera.2008.06.003] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Accepted: 06/04/2008] [Indexed: 01/08/2023]
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Siedlecka U, Arora M, Kolettis T, Soppa GKR, Lee J, Stagg MA, Harding SE, Yacoub MH, Terracciano CMN. Effects of clenbuterol on contractility and Ca2+ homeostasis of isolated rat ventricular myocytes. Am J Physiol Heart Circ Physiol 2008; 295:H1917-26. [PMID: 18775853 DOI: 10.1152/ajpheart.00258.2008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Clenbuterol, a compound classified as a beta2-adrenoceptor (AR) agonist, has been employed in combination with left ventricular assist devices (LVADs) to treat patients with severe heart failure. Previous studies have shown that chronic administration of clenbuterol affects cardiac excitation-contraction coupling. However, the acute effects of clenbuterol and the signaling pathway involved remain undefined. We investigated the acute effects of clenbuterol on isolated ventricular myocyte sarcomere shortening, Ca2+ transients, and L-type Ca2+ current and compared these effects to two other clinically used beta2-AR agonists: fenoterol and salbutamol. Clenbuterol (30 microM) produced a negative inotropic response, whereas fenoterol showed a positive inotropic response. Salbutamol had no significant effects. Clenbuterol reduced Ca2+ transient amplitude and L-type Ca2+ current. Selective beta1-AR blockade did not affect the action of clenbuterol on sarcomere shortening but significantly reduced contractility in the presence of fenoterol and salbutamol (P < 0.05). Incubation with 2 microg/ml pertussis toxin significantly reduced the negative inotropic effects of 30 microM clenbuterol. In addition, overexpression of inhibitory G protein (Gi) by adenoviral transfection induced a stronger clenbuterol-mediated negative inotropic effect, suggesting the involvement of the Gi protein. We conclude that clenbuterol does not increase and, at high concentrations, significantly depresses contractility of isolated ventricular myocytes, an effect not seen with fenoterol or salbutamol. In its negative inotropism, clenbuterol predominantly acts through Gi, and the consequent downstream signaling pathways activation may explain the beneficial effects observed during chronic administration of clenbuterol in patients treated with LVADs.
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Affiliation(s)
- U Siedlecka
- Heart Science Centre, National Heart & Lung Institute, Imperial College, London, United Kingdom
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Hwang IY, Park C, Kehrl JH. Impaired trafficking of Gnai2+/- and Gnai2-/- T lymphocytes: implications for T cell movement within lymph nodes. THE JOURNAL OF IMMUNOLOGY 2007; 179:439-48. [PMID: 17579064 DOI: 10.4049/jimmunol.179.1.439] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Signals generated by the engagement of chemoattractants with their cognate receptors orchestrate lymphocyte movements into and out of lymphoid organs and sites of inflammation. Yet, the role of chemokines in organizing lymphocyte movements in lymphoid organs is controversial. Recent evidence suggests that the extensive network of fibroblastic reticular cells within the T cell areas helps guide T cells. The expression of adhesion molecules and chemokines by fibroblastic reticular cells most likely facilitates their influence on T cell movements. Consistent with this hypothesis, CD4 T cells with defective chemokine receptor signaling move very differently within lymph nodes than do normal cells. For the imaging studies, we used CD4 T cells prepared from Gnai2(-/-) mice, which lack G(alphai2) expression. We first demonstrate that CD4 as well as CD8 T cells from these mice are markedly defective in chemokine receptor signaling. Gnai2(-/-) T cells have profound defects in chemokine-induced intracellular calcium mobilization, chemotaxis, and homing, whereas Gnai2(+/-) T cells exhibit modest defects. Intravital imaging revealed that within the inguinal lymph nodes Gnai2(-/-) CD4 T accumulate at the cortical ridge, poorly accessing the lymph node paracortex. They also lack the customary amoeboid-like cell movements and active membrane projections observed with normal CD4 T cells. These results demonstrate the importance of G(alphai2) for T lymphocyte chemokine receptor signaling and argue that local chemoattractants regulate the movement of CD4 T cells in lymph nodes.
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MESH Headings
- Animals
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- CD4-Positive T-Lymphocytes/pathology
- Calcium Signaling/genetics
- Calcium Signaling/immunology
- Cell Migration Inhibition
- Chemotaxis, Leukocyte/genetics
- Chemotaxis, Leukocyte/immunology
- Down-Regulation/genetics
- Down-Regulation/immunology
- GTP-Binding Protein alpha Subunit, Gi2/biosynthesis
- GTP-Binding Protein alpha Subunit, Gi2/deficiency
- GTP-Binding Protein alpha Subunit, Gi2/genetics
- GTP-Binding Protein alpha Subunit, Gi2/physiology
- Gene Expression Regulation/immunology
- Lymph Nodes/immunology
- Lymph Nodes/metabolism
- Lymph Nodes/pathology
- Lymphocyte Activation/genetics
- Lymphocyte Activation/immunology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Protein Isoforms/biosynthesis
- Protein Isoforms/deficiency
- Protein Isoforms/physiology
- Receptors, Chemokine/antagonists & inhibitors
- Receptors, Chemokine/biosynthesis
- Receptors, Chemokine/physiology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- T-Lymphocyte Subsets/pathology
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Affiliation(s)
- Il-Young Hwang
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA
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39
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McGraw DW, Elwing JM, Fogel KM, Wang WC, Glinka CB, Mihlbachler KA, Rothenberg ME, Liggett SB. Crosstalk between Gi and Gq/Gs pathways in airway smooth muscle regulates bronchial contractility and relaxation. J Clin Invest 2007; 117:1391-8. [PMID: 17415415 PMCID: PMC1838924 DOI: 10.1172/jci30489] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Accepted: 02/06/2007] [Indexed: 11/17/2022] Open
Abstract
Receptor-mediated airway smooth muscle (ASM) contraction via G(alphaq), and relaxation via G(alphas), underlie the bronchospastic features of asthma and its treatment. Asthma models show increased ASM G(alphai) expression, considered the basis for the proasthmatic phenotypes of enhanced bronchial hyperreactivity to contraction mediated by M(3)-muscarinic receptors and diminished relaxation mediated by beta(2)-adrenergic receptors (beta(2)ARs). A causal effect between G(i) expression and phenotype has not been established, nor have mechanisms whereby G(i) modulates G(q)/G(s) signaling. To delineate isolated effects of altered G(i), transgenic mice were generated overexpressing G(alphai2) or a G(alphai2) peptide inhibitor in ASM. Unexpectedly, G(alphai2) overexpression decreased contractility to methacholine, while G(alphai2) inhibition enhanced contraction. These opposite phenotypes resulted from different crosstalk loci within the G(q) signaling network: decreased phospholipase C and increased PKCalpha, respectively. G(alphai2) overexpression decreased beta(2)AR-mediated airway relaxation, while G(alphai2) inhibition increased this response, consistent with physiologically relevant coupling of this receptor to both G(s) and G(i). IL-13 transgenic mice (a model of asthma), which developed increased ASM G(alphai), displayed marked increases in airway hyperresponsiveness when G(alphai) function was inhibited. Increased G(alphai) in asthma is therefore a double-edged sword: a compensatory event mitigating against bronchial hyperreactivity, but a mechanism that evokes beta-agonist resistance. By selective intervention within these multipronged signaling modules, advantageous G(s)/G(q) activities could provide new asthma therapies.
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Affiliation(s)
- Dennis W. McGraw
- Pulmonary Division, Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
Cardiopulmonary Genomics Program, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA.
Division of Allergy and Immunology, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA
| | - Jean M. Elwing
- Pulmonary Division, Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
Cardiopulmonary Genomics Program, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA.
Division of Allergy and Immunology, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA
| | - Kevin M. Fogel
- Pulmonary Division, Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
Cardiopulmonary Genomics Program, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA.
Division of Allergy and Immunology, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA
| | - Wayne C.H. Wang
- Pulmonary Division, Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
Cardiopulmonary Genomics Program, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA.
Division of Allergy and Immunology, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA
| | - Clare B. Glinka
- Pulmonary Division, Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
Cardiopulmonary Genomics Program, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA.
Division of Allergy and Immunology, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA
| | - Kathryn A. Mihlbachler
- Pulmonary Division, Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
Cardiopulmonary Genomics Program, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA.
Division of Allergy and Immunology, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA
| | - Marc E. Rothenberg
- Pulmonary Division, Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
Cardiopulmonary Genomics Program, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA.
Division of Allergy and Immunology, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA
| | - Stephen B. Liggett
- Pulmonary Division, Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
Cardiopulmonary Genomics Program, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA.
Division of Allergy and Immunology, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA
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40
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Hullin R, Matthes J, von Vietinghoff S, Bodi I, Rubio M, D'Souza K, Friedrich Khan I, Rottländer D, Hoppe UC, Mohacsi P, Schmitteckert E, Gilsbach R, Bünemann M, Hein L, Schwartz A, Herzig S. Increased expression of the auxiliary beta(2)-subunit of ventricular L-type Ca(2)+ channels leads to single-channel activity characteristic of heart failure. PLoS One 2007; 2:e292. [PMID: 17356701 PMCID: PMC1808423 DOI: 10.1371/journal.pone.0000292] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Accepted: 02/19/2007] [Indexed: 11/25/2022] Open
Abstract
Background Increased activity of single ventricular L-type Ca2+-channels (L-VDCC) is a hallmark in human heart failure. Recent findings suggest differential modulation by several auxiliary β-subunits as a possible explanation. Methods and Results By molecular and functional analyses of human and murine ventricles, we find that enhanced L-VDCC activity is accompanied by altered expression pattern of auxiliary L-VDCC β-subunit gene products. In HEK293-cells we show differential modulation of single L-VDCC activity by coexpression of several human cardiac β-subunits: Unlike β1 or β3 isoforms, β2a and β2b induce a high-activity channel behavior typical of failing myocytes. In accordance, β2-subunit mRNA and protein are up-regulated in failing human myocardium. In a model of heart failure we find that mice overexpressing the human cardiac CaV1.2 also reveal increased single-channel activity and sarcolemmal β2 expression when entering into the maladaptive stage of heart failure. Interestingly, these animals, when still young and non-failing (“Adaptive Phase”), reveal the opposite phenotype, viz: reduced single-channel activity accompanied by lowered β2 expression. Additional evidence for the cause-effect relationship between β2-subunit expression and single L-VDCC activity is provided by newly engineered, double-transgenic mice bearing both constitutive CaV1.2 and inducible β2 cardiac overexpression. Here in non-failing hearts induction of β2-subunit overexpression mimicked the increase of single L-VDCC activity observed in murine and human chronic heart failure. Conclusions Our study presents evidence of the pathobiochemical relevance of β2-subunits for the electrophysiological phenotype of cardiac L-VDCC and thus provides an explanation for the single L-VDCC gating observed in human and murine heart failure.
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Affiliation(s)
- Roger Hullin
- Department of Cardiology, Swiss Heart Center Bern, University Hospital, Bern, Switzerland
- * To whom correspondence should be addressed. E-mail: (RH); (SH); (AS)
| | - Jan Matthes
- Department of Pharmacology, University of Cologne, Cologne, Germany
| | - Sibylle von Vietinghoff
- Department of Pharmacology, University of Wuerzburg, Wuerzburg, Germany
- Franz Volhard Clinic, Nephrology/Hypertension Section, Medical Faculty of the Charité, Berlin, Germany
| | - Ilona Bodi
- University of Cincinnati College of Medicine, Institute of Molecular Pharmacology and Biophysics, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Marta Rubio
- University of Cincinnati College of Medicine, Institute of Molecular Pharmacology and Biophysics, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Karen D'Souza
- University of Cincinnati College of Medicine, Institute of Molecular Pharmacology and Biophysics, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Ismail Friedrich Khan
- Department of Pharmacology, University of Cologne, Cologne, Germany
- Center of Molecular Medicine, University of Cologne, Cologne, Germany
| | | | - Uta C. Hoppe
- Center of Molecular Medicine, University of Cologne, Cologne, Germany
| | - Paul Mohacsi
- Department of Cardiology, Swiss Heart Center Bern, University Hospital, Bern, Switzerland
| | - Eva Schmitteckert
- Department of Pharmacology, University of Wuerzburg, Wuerzburg, Germany
| | - Ralf Gilsbach
- Department of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Moritz Bünemann
- Department of Pharmacology, University of Wuerzburg, Wuerzburg, Germany
| | - Lutz Hein
- Department of Pharmacology, University of Wuerzburg, Wuerzburg, Germany
- Department of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Arnold Schwartz
- University of Cincinnati College of Medicine, Institute of Molecular Pharmacology and Biophysics, University of Cincinnati, Cincinnati, Ohio, United States of America
- * To whom correspondence should be addressed. E-mail: (RH); (SH); (AS)
| | - Stefan Herzig
- Department of Pharmacology, University of Cologne, Cologne, Germany
- Center of Molecular Medicine, University of Cologne, Cologne, Germany
- * To whom correspondence should be addressed. E-mail: (RH); (SH); (AS)
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41
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Rottlaender D, Matthes J, Vatner SF, Seifert R, Herzig S. Functional adenylyl cyclase inhibition in murine cardiomyocytes by 2'(3')-O-(N-methylanthraniloyl)-guanosine 5'-[gamma-thio]triphosphate. J Pharmacol Exp Ther 2007; 321:608-15. [PMID: 17284671 DOI: 10.1124/jpet.106.118422] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Beta1-adrenergic receptor activation stimulates cardiac L-type Ca2+ channels via adenylyl cyclases (ACs), with AC5 and AC6 being the most important cardiac isoforms. Recently, we have identified 2'(3')-O-(N-methylanthraniloyl)-guanosine 5'-[gamma-thio-]triphosphate (MANT-GTPgammaS) as a potent competitive AC inhibitor. Intriguingly, MANT-GTPgammaS inhibits AC5 and -6 more potently than other cyclases. These data prompted us to study the effects of MANT-GTPgammaS on L-type Ca2+ currents (ICa,L) in ventricular myocytes of wild-type (WT) and AC5-deficient (AC5-/-) mice by whole-cell recordings. In wild-type myocytes, MANT-GTPgammaS attenuated ICa,L stimulation following isoproterenol application in a concentration-dependent manner (control, +77+/-13%; 100 nM MANT-GTPgammaS, +43+/-6%; 1 microM MANT-GTPgammaS, +21+/-9%; p<0.05). The leftward shift of current-voltage curves was abolished by 1 microM but not by 100 nM MANT-GTPgammaS. In myocytes from AC5-/- mice, the residual stimulation of ICa,L was not further attenuated by the nucleotide, indicating AC5 to be the major AC isoform mediating acute beta-adrenergic stimulation in WT mice. Interestingly, basal ICa,L was lowered by 1 microM but not by 100 nM MANT-GTPgammaS. The decrease was less pronounced in myocytes from AC5-/- mice compared with wild types (-23+/-1 versus -40+/-7%), indicating basal ICa,L to be partly driven by AC5. Collectively, we found a concentration-dependent inhibition of ICa,L by MANT-GTPgammaS, both under basal conditions and following beta-adrenergic stimulation. Comparison of data from wild-type and AC5-deficient mice indicates that AC5 plays a major role in ICa,L activation and that MANT-GTPgammaS predominantly acts via AC5 inhibition.
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Affiliation(s)
- Dennis Rottlaender
- Department of Pharmacology, Center for Molecular Medicine, University of Cologne, Gleueler Str. 24, D-50931 Köln, Germany
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42
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Ryall JG, Sillence MN, Lynch GS. Systemic administration of beta2-adrenoceptor agonists, formoterol and salmeterol, elicit skeletal muscle hypertrophy in rats at micromolar doses. Br J Pharmacol 2006; 147:587-95. [PMID: 16432501 PMCID: PMC1751341 DOI: 10.1038/sj.bjp.0706669] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
beta(2)-Adrenoceptor agonists provide a potential therapy for muscle wasting and weakness, but their use may be limited by adverse effects on the heart, mediated in part, by beta(1)-adrenoceptor activation. Two beta(2)-agonists, formoterol and salmeterol, are approved for treating asthma and have an extended duration of action and increased safety, associated with greater beta(2)-adrenoceptor selectivity. The pharmacological profiles of formoterol and salmeterol and their effects on skeletal and cardiac muscle mass were investigated in 12-week-old, male F344 rats. Formoterol and salmeterol were each administered via daily i.p. injection at one of seven doses (ranging from 1 to 2,000 microg kg(-1) day(-1)), for 4 weeks. Rats were anaesthetised and the EDL and soleus muscles and the heart were excised and weighed. Dose-response curves were constructed based on skeletal and cardiac muscle hypertrophy. Formoterol was more potent than salmeterol, with a significantly lower ED(50) in EDL muscles (1 and 130 microg kg(-1) day(-1), P <0.05), whereas salmeterol had greater intrinsic activity than formoterol in both EDL and soleus muscles (12% greater hypertrophy than formoterol). The drugs had similar potency and intrinsic activity in the heart, with a smaller leftward shift for formoterol than seen in skeletal muscle. A dose of 25 microg kg(-1) day(-1) of formoterol elicited greater EDL and soleus hypertrophy than salmeterol, but resulted in similar beta-adrenoceptor downregulation. These results show that doses as low as 1 microg kg(-1) day(-1) of formoterol can elicit significant muscle hypertrophy with minimal cardiac hypertrophy and provide important information regarding the potential therapeutic use of formoterol and salmeterol for muscle wasting.
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MESH Headings
- Adrenergic beta-2 Receptor Agonists
- Adrenergic beta-Agonists/administration & dosage
- Adrenergic beta-Agonists/pharmacology
- Albuterol/administration & dosage
- Albuterol/analogs & derivatives
- Albuterol/pharmacology
- Animals
- Cardiomegaly/chemically induced
- Dose-Response Relationship, Drug
- Down-Regulation
- Ethanolamines/administration & dosage
- Ethanolamines/pharmacology
- Formoterol Fumarate
- Heart/drug effects
- Male
- Muscle Fibers, Fast-Twitch/drug effects
- Muscle Fibers, Fast-Twitch/metabolism
- Muscle Fibers, Fast-Twitch/pathology
- Muscle Fibers, Slow-Twitch/drug effects
- Muscle Fibers, Slow-Twitch/metabolism
- Muscle Fibers, Slow-Twitch/pathology
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Myocardium/metabolism
- Myocardium/pathology
- Rats
- Rats, Inbred F344
- Receptors, Adrenergic, beta-2/metabolism
- Salmeterol Xinafoate
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Affiliation(s)
- James G Ryall
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Grattan Street, Victoria 3010, Australia
| | - Martin N Sillence
- School of Agricultural and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales 2678, Australia
| | - Gordon S Lynch
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Grattan Street, Victoria 3010, Australia
- Author for correspondence:
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44
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Tanaka S, Yamagishi R, Tsutsui M, Kishida T, Murakami M, Kuroda J, Yoshida T. Tissue- and dose-dependent alteration of stress-inducible proteins by beta2-adrenoceptor agonist, salbutamol, in rats. J Toxicol Sci 2006; 30:305-14. [PMID: 16404139 DOI: 10.2131/jts.30.305] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The effects of selective beta(2)-adrenoceptor agonists on proinflammatory cytokines and the expression of stress-inducible proteins have not yet been clarified. We investigated the effect of a higher dose (60 mg/kg intravenously) of salbutamol, a selective beta(2)-adrenoceptor agonist, on the induction of interleukin (IL)-1beta, IL-6 and tumor necrosis factor (TNF)-alpha in plasma and the expression of protein and mRNA of metallothioein-1 (MT-1), heme oxygenase-1 (HO-1) and inducible nitric oxide synthase (iNOS) in heart, lung, liver and spleen in rats. The plasma IL-6 concentration was significantly increased after administration with a maximum increase at 3 hr in a dose-dependent manner, but IL-1beta and TNF-alpha concentrations were not changed. MT-1 mRNA increased in heart, lung and liver, but not in spleen, and MT-1 protein increased in endocardium, fibroblasts of lung and periportal regions in liver. HO-1 mRNA was not changed in lung, decreased at 3 hr in liver and spleen, and increased at 6 hr in liver. Contrary to liver, HO-1 mRNA in the heart increased at 3 hr and decreased at 6 hr. HO-1 protein increased in cardiomyocytes and centrilobular regions in the liver. iNOS mRNA increased in lung, liver and spleen, but decreased in the heart, and iNOS protein increased in alveolar type II cells and hepatocytes, and decreased in necrotic cardiomyocytes. In contrast, a lower dose (6 mg/kg intravenously) of salbutamol suppressed lipopolysaccharide-induced HO-1 and iNOS mRNA. We conclude that salbutamol tissue- and dose-dependently alters the expression of stress-inducible proteins.
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Affiliation(s)
- Satoru Tanaka
- Division of Toxicological Research, Kissei Pharmaceutical Co. Ltd., Nagano, Japan.
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45
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Pereira L, Matthes J, Schuster I, Valdivia HH, Herzig S, Richard S, Gómez AM. Mechanisms of [Ca2+]i transient decrease in cardiomyopathy of db/db type 2 diabetic mice. Diabetes 2006; 55:608-15. [PMID: 16505222 DOI: 10.2337/diabetes.55.03.06.db05-1284] [Citation(s) in RCA: 197] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cardiovascular disease is the leading cause of death in the diabetic population. However, molecular mechanisms underlying diabetic cardiomyopathy remain unclear. We analyzed Ca2+-induced Ca2+ release and excitation-contraction coupling in db/db obese type 2 diabetic mice and their control littermates. Echocardiography showed a systolic dysfunction in db/db mice. Two-photon microscopy identified intracellular calcium concentration ([Ca2+]i) transient decrease in cardiomyocytes within the whole heart, which was also found in isolated myocytes by confocal microscopy. Global [Ca2+]i transients are constituted of individual Ca2+ sparks. Ca2+ sparks in db/db cardiomyocytes were less frequent than in +/+ myocytes, partly because of a depression in sarcoplasmic reticulum Ca2+ load but also because of a reduced expression of ryanodine receptor Ca2+ channels (RyRs), revealed by [3H]ryanodine binding assay. Ca2+ efflux through Na+/Ca2+ exchanger was increased in db/db myocytes. Calcium current, I(Ca), triggers sarcoplasmic reticulum Ca2+ release and is also involved in sarcoplasmic reticulum Ca2+ refilling. Macroscopic I(Ca) was reduced in db/db cells, but single Ca2+ channel activity was similar, suggesting that diabetic myocytes express fewer functional Ca2+ channels, which was confirmed by Western blots. These results demonstrate that db/db mice show depressed cardiac function, at least in part, because of a general reduction in the membrane permeability to Ca2+. As less Ca2+ enters the cell through I(Ca), less Ca2+ is released through RyRs.
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Affiliation(s)
- Laetitia Pereira
- Institut National de la Santé et de la Recherche Médicale U-637, University of Montpellier 1, France
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Abstract
Heterotrimeric G proteins are key players in transmembrane signaling by coupling a huge variety of receptors to channel proteins, enzymes, and other effector molecules. Multiple subforms of G proteins together with receptors, effectors, and various regulatory proteins represent the components of a highly versatile signal transduction system. G protein-mediated signaling is employed by virtually all cells in the mammalian organism and is centrally involved in diverse physiological functions such as perception of sensory information, modulation of synaptic transmission, hormone release and actions, regulation of cell contraction and migration, or cell growth and differentiation. In this review, some of the functions of heterotrimeric G proteins in defined cells and tissues are described.
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Affiliation(s)
- Nina Wettschureck
- Institute of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, D-69120 Heidelberg, Germany
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47
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Fujino H, Regan JW. EP(4) prostanoid receptor coupling to a pertussis toxin-sensitive inhibitory G protein. Mol Pharmacol 2005; 69:5-10. [PMID: 16204467 DOI: 10.1124/mol.105.017749] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The EP(2) and EP(4) prostanoid receptor subtypes are G-protein-coupled receptors for prostaglandin E(2) (PGE(2)). Both receptor subtypes are known to couple to the stimulatory guanine nucleotide binding protein (Galpha(s)) and, after stimulation with PGE(2), can increase the formation of intracellular cAMP. In addition, PGE(2) stimulation of the EP(4) receptor can activate phosphatidylinositol 3-kinase (PI3K) leading to phosphorylation of the extracellular signal-regulated kinases (ERKs) and induction of early growth response factor-1 (EGR-1). We now report that the PGE(2)-mediated phosphorylation of the ERKs and induction of EGR-1 can be blocked by pretreatment of EP(4)-expressing cells with pertussis toxin (PTX). Furthermore, pretreatment with PTX increased the amount of PGE(2)-stimulated intracellular cAMP formation in EP(4)-expressing cells but not in EP(2)-expressing cells. These data indicate that the EP(4) prostanoid receptor subtype, but not the EP(2), couples to a PTX-sensitive inhibitory G-protein (Galpha(i)) that can inhibit cAMP-dependent signaling and activate PI3K/ERK-dependent signaling.
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Affiliation(s)
- Hiromichi Fujino
- Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson, AZ 85721-0207, USA
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48
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Ait-Mamar B, Cailleret M, Rucker-Martin C, Bouabdallah A, Candiani G, Adamy C, Duvaldestin P, Pecker F, Defer N, Pavoine C. The Cytosolic Phospholipase A2 Pathway, a Safeguard of β2-Adrenergic Cardiac Effects in Rat. J Biol Chem 2005; 280:18881-90. [PMID: 15728587 DOI: 10.1074/jbc.m410305200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We have recently demonstrated that in human heart, beta2-adrenergic receptors (beta2-ARs) are biochemically coupled not only to the classical adenylyl cyclase (AC) pathway but also to the cytosolic phospholipase A2 (cPLA2) pathway (Pavoine, C., Behforouz, N., Gauthier, C., Le Gouvello, S., Roudot-Thoraval, F., Martin, C. R., Pawlak, A., Feral, C., Defer, N., Houel, R., Magne, S., Amadou, A., Loisance, D., Duvaldestin, P., and Pecker, F. (2003) Mol. Pharmacol. 64, 1117-1125). In this study, using Fura-2-loaded cardiomyocytes isolated from adult rats, we showed that stimulation of beta2-ARs triggered an increase in the amplitude of electrically stimulated [Ca2+]i transients and contractions. This effect was abolished with the PKA inhibitor, H89, but greatly enhanced upon addition of the selective cPLA2 inhibitor, AACOCF3. The beta2-AR/cPLA2 inhibitory pathway involved G(i) and MSK1. Potentiation of beta2-AR/AC/PKA-induced Ca2+ responses by AACOCF3 did not rely on the enhancement of AC activity but was associated with eNOS phosphorylation (Ser1177) and L-NAME-sensitive NO production. This was correlated with PKA-dependent phosphorylation of PLB (Ser16). The constraint exerted by the beta2-AR/cPLA2 pathway on the beta2-AR/AC/PKA-induced Ca2+ responses required integrity of caveolar structures and was impaired by Filipin III treatment. Immunoblot analyses demonstrated zinterol-induced translocation of cPLA and its cosedimentation with MSK1, eNOS, PLB, and sarcoplasmic reticulum Ca2+ pump (SERCA) 2a in a low density caveolin-3-enriched membrane fraction. This inferred the gathering of beta2-AR signaling effectors around caveolae/sarcoplasmic reticulum (SR) functional platforms. Taken together, these data highlight cPLA as a cardiac beta2-AR signaling pathway that limits beta2-AR/AC/PKA-induced Ca2+ responses in adult rat cardiomyocytes through the impairment of eNOS activation and PLB phosphorylation.
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Affiliation(s)
- Bouziane Ait-Mamar
- Inserm, U581, University of Paris, XII-Val de Marne, Créteil F-94010, France
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Pavoine C, Defer N. The cardiac beta2-adrenergic signalling a new role for the cPLA2. Cell Signal 2005; 17:141-52. [PMID: 15494206 DOI: 10.1016/j.cellsig.2004.09.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2004] [Revised: 09/01/2004] [Accepted: 09/01/2004] [Indexed: 01/08/2023]
Abstract
The cardiac actions of catecholamines have long been attributed to the predominant beta(1)-AR subtype that couples to the classical Gs/AC/cAMP pathway. Recent research clearly indicates that cardiac beta(2)-ARs play a functional role in healthy heart and assume increasing importance in failing and aged heart. beta(2)-ARs are primarily coupled to an atypical compartmentalized cAMP pathway, regulated by phosphorylation and/or oligomerization of beta(2)-ARs, and under the control of additional beta(2)-AR/Gi-coupled lipidic pathways, the impact of which seems to vary depending on the animal species, the developmental and pathophysiological state. This review focuses, more especially, on one of the last identified beta(2)-AR/Gi pathway, namely the cPLA(2).
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MESH Headings
- Animals
- Arachidonic Acid/metabolism
- Cardiotonic Agents/pharmacology
- Caveolae/metabolism
- Caveolae/physiology
- Cyclic AMP/metabolism
- Dimerization
- GTP-Binding Protein alpha Subunits, Gi-Go/physiology
- GTP-Binding Protein alpha Subunits, Gs/physiology
- Group IV Phospholipases A2
- Heart/drug effects
- Heart/physiology
- Humans
- Isoenzymes/chemistry
- Isoenzymes/physiology
- Models, Cardiovascular
- Myocardium/enzymology
- Myocardium/metabolism
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/physiology
- Phosphatidylinositol 3-Kinases/physiology
- Phospholipases A/chemistry
- Phospholipases A/physiology
- Receptors, Adrenergic, beta-1/physiology
- Receptors, Adrenergic, beta-2/metabolism
- Receptors, Adrenergic, beta-2/physiology
- Signal Transduction/physiology
- Species Specificity
- Ventricular Dysfunction/metabolism
- Ventricular Dysfunction/physiopathology
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Foerster K, Kaeferstein T, Groner F, Engelhardt S, Matthes J, Koch WJ, Lohse MJ, Herzig S. Calcium channel function and regulation in beta 1- and beta 2-adrenoceptor transgenic mice. Naunyn Schmiedebergs Arch Pharmacol 2004; 369:490-5. [PMID: 15083268 DOI: 10.1007/s00210-004-0928-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2003] [Accepted: 03/22/2004] [Indexed: 12/13/2022]
Abstract
Cardiac effects of catecholamines on the L-type calcium channel depend on beta-adrenoceptor subtype (beta(1)- vs. beta(2)-adrenoceptor). Chronic overexpression of these receptors leads to hypertrophy and early death at moderate (beta(1)) or excessive (beta(2)) levels of overexpression respectively. In order to examine the role of L-type calcium channels in altered cardiomyocyte calcium homeostasis found with beta(1)-adrenoceptor overexpression, and to understand the quantitative differences between beta-adrenoceptor subtypes regarding calcium channel regulation, we examined single channels in myocytes obtained from beta(1)- and beta(2)-adrenoceptor transgenic mice. The effects of the agonist isoproterenol were investigated and compared with acute receptor stimulation in the respective non-transgenic littermates. Channels from beta(1)-adrenoceptor transgenic mice have normal baseline activity, and channel number is not reduced. This contrasts to previous findings with beta(2)-adrenoceptor transgenic mice, where channel activity is depressed. Isoproterenol is unable to stimulate channel activity in both transgenic models. In conclusion, the L-type calcium channel is not likely to be involved in alterations of calcium handling of beta(1)-adrenoceptor transgenic myocytes. Furthermore, chronic beta(1)-adrenoceptor overexpression does not depress channel activity, giving another example of the difference between beta(1)- and beta(2)-adrenoceptor signal transduction.
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MESH Headings
- Adrenergic beta-Agonists/pharmacology
- Animals
- Calcium Channel Blockers/metabolism
- Calcium Channels/drug effects
- Calcium Channels/physiology
- Isoproterenol/pharmacology
- Isradipine/metabolism
- Mice
- Mice, Transgenic
- Myocytes, Cardiac
- Receptors, Adrenergic, beta-1/drug effects
- Receptors, Adrenergic, beta-1/physiology
- Receptors, Adrenergic, beta-2/drug effects
- Receptors, Adrenergic, beta-2/physiology
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Affiliation(s)
- Katharina Foerster
- Department of Pharmacology, University of Cologne, Gleueler Strasse 24, 50931 Cologne, Germany
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