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Doan ND, Nguyen TTM, Létourneau M, Turcotte K, Fournier A, Chatenet D. Biochemical and pharmacological characterization of nuclear urotensin-II binding sites in rat heart. Br J Pharmacol 2012; 166:243-57. [PMID: 22044114 DOI: 10.1111/j.1476-5381.2011.01710.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND AND PURPOSE During the past decade, a few GPCRs have been characterized at the nuclear membrane where they exert complementary physiological functions. In this study, we investigated (1) the presence of a functional urotensin-II (U-II) receptor (UT) in rat heart nuclear extracts and (2) the propensity of U-II and U-II-related peptide (URP) to cross the plasma membrane in a receptor-independent manner. EXPERIMENTAL APPROACH Biochemical and pharmacological methods including competitive binding assays, photoaffinity labelling, immunoblotting as well as de novo RNA synthesis were used to characterize the presence of functional UT receptors in rat heart nuclei. In addition, confocal microscopy and flow cytometry analysis were used to investigate the cellular uptake of fluorescent U-II and URP derivatives. KEY RESULTS The presence of specific U-II binding sites was demonstrated in rat heart nuclear extracts. Moreover, such subcellular localization was also observed in monkey heart extracts. In vitro transcription initiation assays on rat, freshly isolated, heart nuclei suggested that nuclear UT receptors are functional, and that U-II, but not URP, participates in nuclear UT-associated gene expression. Surprisingly, hU-II and URP efficiently crossed the plasma membrane in a receptor-independent mechanism involving endocytosis through caveolin-coated pits; this uptake of hU-II, but not that of URP, was dependent on extracellular pH. CONCLUSION Our results suggest that (1) U-II and URP can differentially modulate nuclear UT functions such as gene expression, and (2) both ligands can reach the internal cellular space through a receptor-independent mechanism.
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Affiliation(s)
- N D Doan
- Université du Québec, INRS - Institut Armand-Frappier, Ville de Laval, QC, Canada
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52
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Doan ND, Chatenet D, Létourneau M, Vaudry H, Vaudry D, Fournier A. Receptor-independent cellular uptake of pituitary adenylate cyclase-activating polypeptide. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:940-9. [DOI: 10.1016/j.bbamcr.2012.02.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 01/31/2012] [Accepted: 02/01/2012] [Indexed: 11/28/2022]
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Wright CD, Wu SC, Dahl EF, Sazama AJ, O'Connell TD. Nuclear localization drives α1-adrenergic receptor oligomerization and signaling in cardiac myocytes. Cell Signal 2012; 24:794-802. [PMID: 22120526 PMCID: PMC3393107 DOI: 10.1016/j.cellsig.2011.11.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 11/08/2011] [Indexed: 11/17/2022]
Abstract
Conventional models of G-protein coupled receptor (GPCR) signaling describe cell surface receptors binding to external ligands, such as hormones or circulating peptides, to induce intracellular signaling and a physiologic response. However, recent studies identify new paradigms indicating that GPCRs localize to and signal at the nucleus and that GPCR oligomers can influence receptor function. Previously, we reported that endogenous α1-adrenergic receptors (α1-ARs) localize to and signal at the nuclei in adult cardiac myocytes. In this study, we examined the mechanisms behind α1-AR nuclear localization and how nuclear localization impacted receptor function. We verified that endogenous α1-ARs localized to the nuclear membrane of intact nuclei isolated from wild-type adult cardiac myocytes. Next, we identified and disrupted putative nuclear localization sequences in both the α1A- and α1B-adrenergic receptors, which led to mis-localization of α1-ARs in cultured adult cardiac myocytes. Using these mutants, we demonstrated that nuclear localization was required for α1-signaling in adult cardiac myocytes. We also found that the nuclear export inhibitor leptomycin B inhibited α1-AR signaling, indicating α1-AR signaling must arise in the nucleus in adult cardiac myocytes. Finally, we found that co-localization of the α1-subtypes at the nuclei in adult cardiac myocytes facilitated the formation of receptor oligomers that could affect receptor signaling. In summary, our data indicate that α1-AR nuclear localization can drive the formation of receptor oligomers and regulate signaling in adult cardiac myocytes.
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MESH Headings
- Animals
- Cell Nucleus/metabolism
- Cells, Cultured
- Fluorescence Resonance Energy Transfer
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mutation
- Myocytes, Cardiac/cytology
- Myocytes, Cardiac/metabolism
- Protein Multimerization
- Receptors, Adrenergic, alpha-1/analysis
- Receptors, Adrenergic, alpha-1/genetics
- Receptors, Adrenergic, alpha-1/metabolism
- Signal Transduction
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Affiliation(s)
- Casey D Wright
- Cardiovascular Health Research Center, Sanford Research/USD, Sioux Falls, SD 57104, United States
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Pönicke K, Gergs U, Buchwalow IB, Hauptmann S, Neumann J. On the presence of serotonin in mammalian cardiomyocytes. Mol Cell Biochem 2012; 365:301-12. [PMID: 22367115 DOI: 10.1007/s11010-012-1270-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 02/16/2012] [Indexed: 10/28/2022]
Abstract
Pleiotropic effects of serotonin (5-HT) in the cardiovascular system are well documented. However, it remains to be elucidated, whether 5-HT is present in adult mammalian cardiomyocytes. To address this issue, we investigated the levels of 5-HT in blood, plasma, platelets, cardiac tissue, and cardiomyocytes from adult mice and for comparison in human right atrial tissue. Immunohistochemically, 5-HT was hardly found in mouse cardiac tissue, but small amounts could be detected in renal preparations, whereas adrenal preparations revealed a strong positive immunoreaction for 5-HT. Using a sensitive HPLC detection system, 5-HT was also detectable in the mouse heart and human atrium. Furthermore, we could identify 5-HT in isolated cardiomyocytes from adult mice. These findings were supported by detection of the activity of 5-HT-forming enzymes-tryptophan hydroxylase and aromatic L-amino acid decarboxylase-in isolated cardiomyocytes from adult mice and by inhibition of these enzymes with p-chlorophenylalanine and 3-hydroxybenzyl hydrazine. Addition of the first intermediate of 5-HT generation, that is 5-hydroxytryptophan, enhanced the 5-HT level and inhibition of monoamine oxidase by tranylcypromine further increased the level of 5-HT. Our findings reveal the presence and synthesis of 5-HT in cardiomyocytes of the mammalian heart implying that 5-HT may play an autocrine and/or paracrine role in the heart.
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Affiliation(s)
- Klaus Pönicke
- Medical Faculty, Institute of Pharmacology and Toxicology, Martin-Luther-University Halle-Wittenberg, Magdeburger Str. 4, 06112, Halle (Saale), Germany
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55
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Huang Y, Cavanaugh A, Breitwieser GE. Regulation of stability and trafficking of calcium-sensing receptors by pharmacologic chaperones. ADVANCES IN PHARMACOLOGY 2012; 62:143-73. [PMID: 21907909 DOI: 10.1016/b978-0-12-385952-5.00007-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Gain- or loss-of-function mutations and polymorphisms of the calcium-sensing receptor (CaSR) cause Ca(2+) handling diseases. Altered expression and/or signaling of wild-type CaSR can also contribute to pathology. Recent studies have demonstrated that a significant proportion of mutations cause altered targeting and/or trafficking of CaSR to the plasma membrane. Pharmacological approaches to rescue of CaSR function include treatment with allosteric modulators, which potentiate the effects of the orthosteric agonist Ca(2+). Dissection of the mechanism(s) contributing to allosteric agonist-mediated rescue of loss-of-function CaSR mutants has demonstrated pharmacologic chaperone actions coincident with CaSR biosynthesis. The distinctive responses to the allosteric agonist (NPS R-568), which promotes CaSR stability, and the allosteric antagonist (NPS 2143), which promotes CaSR degradation, have led to a model for a conformational checkpoint during CaSR biosynthesis. The conformational checkpoint would "tune" CaSR biosynthesis to cellular signaling state. Navigation of a distinct checkpoint for endoplasmic release can also be augmented by pharmacologic chaperones. The diverse, post-endoplasmic reticulum quality control site(s) for pharmacologic chaperone modulation of CaSR stability and trafficking redefines the role(s) of allosteric modulators in regulation of overall GPCR function.
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Affiliation(s)
- Ying Huang
- Cancer Drug Research Laboratory, McGill University, Royal Victoria Hospital, Montreal, Quebec, Canada
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56
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Chatenet D, Nguyen TTM, Létourneau M, Fournier A. Update on the urotensinergic system: new trends in receptor localization, activation, and drug design. Front Endocrinol (Lausanne) 2012; 3:174. [PMID: 23293631 PMCID: PMC3533682 DOI: 10.3389/fendo.2012.00174] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 12/10/2012] [Indexed: 12/17/2022] Open
Abstract
The urotensinergic system plays central roles in the physiological regulation of major mammalian organ systems, including the cardiovascular system. As a matter of fact, this system has been linked to numerous pathophysiological states including atherosclerosis, heart failure, hypertension, diabetes as well as psychological, and neurological disorders. The delineation of the (patho)physiological roles of the urotensinergic system has been hampered by the absence of potent and selective antagonists for the urotensin II-receptor (UT). Thus, a more precise definition of the molecular functioning of the urotensinergic system, in normal conditions as well as in a pathological state is still critically needed. The recent discovery of nuclear UT within cardiomyocytes has highlighted the cellular complexity of this system and suggested that UT-associated biological responses are not only initiated at the cell surface but may result from the integration of extracellular and intracellular signaling pathways. Thus, such nuclear-localized receptors, regulating distinct signaling pathways, may represent new therapeutic targets. With the recent observation that urotensin II (UII) and urotensin II-related peptide (URP) exert different biological effects and the postulate that they could also have distinct pathophysiological roles in hypertension, it appears crucial to reassess the recognition process involving UII and URP with UT, and to push forward the development of new analogs of the UT system aimed at discriminating UII- and URP-mediated biological activities. The recent development of such compounds, i.e. urocontrin A and rUII(1-7), is certainly useful to decipher the specific roles of UII and URP in vitro and in vivo. Altogether, these studies, which provide important information regarding the pharmacology of the urotensinergic system and the conformational requirements for binding and activation, will ultimately lead to the development of potent and selective drugs.
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Affiliation(s)
- David Chatenet
- Laboratoire d'études moléculaires et pharmacologiques des peptides, INRS – Institut Armand-Frappier, Université du Québec, Ville de LavalQC, Canada
- Laboratoire International Associé Samuel de Champlain (INSERM/INRS-Université de Rouen)France
- *Correspondence: David Chatenet and Alain Fournier, Laboratoire d'études moléculaires et pharmacologiques des peptides, INRS – Institut Armand-Frappier, Université du Québec, 531 Boulevard des Prairies, Ville de Laval, QC H7V 1B7, Canada. e-mail: ;
| | - Thi-Tuyet M. Nguyen
- Laboratoire d'études moléculaires et pharmacologiques des peptides, INRS – Institut Armand-Frappier, Université du Québec, Ville de LavalQC, Canada
- Laboratoire International Associé Samuel de Champlain (INSERM/INRS-Université de Rouen)France
| | - Myriam Létourneau
- Laboratoire d'études moléculaires et pharmacologiques des peptides, INRS – Institut Armand-Frappier, Université du Québec, Ville de LavalQC, Canada
- Laboratoire International Associé Samuel de Champlain (INSERM/INRS-Université de Rouen)France
| | - Alain Fournier
- Laboratoire d'études moléculaires et pharmacologiques des peptides, INRS – Institut Armand-Frappier, Université du Québec, Ville de LavalQC, Canada
- Laboratoire International Associé Samuel de Champlain (INSERM/INRS-Université de Rouen)France
- *Correspondence: David Chatenet and Alain Fournier, Laboratoire d'études moléculaires et pharmacologiques des peptides, INRS – Institut Armand-Frappier, Université du Québec, 531 Boulevard des Prairies, Ville de Laval, QC H7V 1B7, Canada. e-mail: ;
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Tadevosyan A, Vaniotis G, Allen BG, Hébert TE, Nattel S. G protein-coupled receptor signalling in the cardiac nuclear membrane: evidence and possible roles in physiological and pathophysiological function. J Physiol 2011; 590:1313-30. [PMID: 22183719 DOI: 10.1113/jphysiol.2011.222794] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
G protein-coupled receptors (GPCRs) play key physiological roles in numerous tissues, including the heart, and their dysfunction influences a wide range of cardiovascular diseases. Recently, the notion of nuclear localization and action of GPCRs has become more widely accepted. Nuclear-localized receptors may regulate distinct signalling pathways, suggesting that the biological responses mediated by GPCRs are not solely initiated at the cell surface but may result from the integration of extracellular and intracellular signalling pathways. Many of the observed nuclear effects are not prevented by classical inhibitors that exclusively target cell surface receptors, presumably because of their structures, lipophilic properties, or affinity for nuclear receptors. In this topical review, we discuss specifically how angiotensin-II, endothelin, β-adrenergic and opioid receptors located on the nuclear envelope activate signalling pathways, which convert intracrine stimuli into acute responses such as generation of second messengers and direct genomic effects, and thereby participate in the development of cardiovascular disorders.
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Affiliation(s)
- Artavazd Tadevosyan
- Department of Medicine, Université de Montréal, Montréal, Québec, Canada H3C 3J7
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58
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Cook JL, Re RN. Lessons from in vitro studies and a related intracellular angiotensin II transgenic mouse model. Am J Physiol Regul Integr Comp Physiol 2011; 302:R482-93. [PMID: 22170617 DOI: 10.1152/ajpregu.00493.2011] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In the classical renin-angiotensin system, circulating ANG II mediates growth stimulatory and hemodynamic effects through the plasma membrane ANG II type I receptor, AT1. ANG II also exists in the intracellular space in some native cells, and tissues and can be upregulated in diseases, including hypertension and diabetes. Moreover, intracellular AT1 receptors can be found associated with endosomes, nuclei, and mitochondria. Intracellular ANG II can function in a canonical fashion through the native receptor and also in a noncanonical fashion through interaction with alternative proteins. Likewise, the receptor and proteolytic fragments of the receptor can function independently of ANG II. Participation of the receptor and ligand in alternative intracellular pathways may serve to amplify events that are initiated at the plasma membrane. We review historical and current literature relevant to ANG II, compared with other intracrines, in tissue culture and transgenic models. In particular, we describe a new transgenic mouse model, which demonstrates that intracellular ANG II is linked to high blood pressure. Appreciation of the diverse, pleiotropic intracellular effects of components of the renin-angiotensin system should lead to alternative disease treatment targets and new therapies.
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Affiliation(s)
- Julia L Cook
- Laboratory of Molecular Genetics, Department of Research, New Orleans, LA 70121, USA.
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Abstract
Catecholamines play a key role in the regulation of cardiovascular function, classically through ß(1/2)-adrenoreceptors (AR) activation. After ß(3)-AR cloning in the late 1980s, convincing evidence for ß(3)-AR expression and function in cardiovascular tissues recently initiated a reexamination of their involvement in the pathophysiology of cardiovascular diseases. Their upregulation in diseased cardiovascular tissues and resistance to desensitization suggest they may be attractive therapeutic targets. They may substitute for inoperant ß(1/2)-AR to mediate vasodilation in diabetic or atherosclerotic vessels. In cardiac ventricle, their contractile effects are functionally antipathetic to those of ß(1/2)-AR; in normal heart, ß(3)-ARs may mediate a moderate negative inotropic effect, but in heart failure, it may protect against adverse effects of excessive catecholamine stimulation by action on excitation-contraction coupling, electrophysiology, or remodelling. Thus, prospective studies in animals and patients at different stages of heart failure should lead to identify the best therapeutic window to use ß(3)-AR agonists and/or antagonists.
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60
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Vaniotis G, Allen BG, Hébert TE. Nuclear GPCRs in cardiomyocytes: an insider's view of β-adrenergic receptor signaling. Am J Physiol Heart Circ Physiol 2011; 301:H1754-64. [PMID: 21890692 DOI: 10.1152/ajpheart.00657.2011] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
In recent years, we have come to appreciate the complexity of G protein-coupled receptor signaling in general and β-adrenergic receptor (β-AR) signaling in particular. Starting originally from three β-AR subtypes expressed in cardiomyocytes with relatively simple, linear signaling cascades, it is now clear that there are large receptor-based networks which provide a rich and diverse set of responses depending on their complement of signaling partners and the physiological state. More recently, it has become clear that subcellular localization of these signaling complexes also enriches the diversity of phenotypic outcomes. Here, we review our understanding of the signaling repertoire controlled by nuclear β-AR subtypes as well our understanding of the novel roles for G proteins themselves in the nucleus, with a special focus, where possible, on their effects in cardiomyocytes. Finally, we discuss the potential pathological implications of alterations in nuclear β-AR signaling.
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