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Poirier B, Pasquier O, Chenede X, Corbier A, Prigent P, Azam A, Bernard C, Guillotel M, Gillot F, Riva L, Briand V, Ingenito R, Gauzy-Lazo L, Duclos O, Philippo C, Maillere B, Bianchi E, Mallart S, Janiak P, Illiano S. R2R01: A long-acting single-chain peptide agonist of RXFP1 for renal and cardiovascular diseases. Br J Pharmacol 2024; 181:1993-2011. [PMID: 38450758 DOI: 10.1111/bph.16338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 01/08/2024] [Accepted: 01/11/2024] [Indexed: 03/08/2024] Open
Abstract
BACKGROUND The therapeutic potential of relaxin for heart failure and renal disease in clinical trials is hampered by the short half-life of serelaxin. Optimization of fatty acid-acetylated single-chain peptide analogues of relaxin culminated in the design and synthesis of R2R01, a potent and selective RXFP1 agonist with subcutaneous bioavailability and extended half-life. EXPERIMENTAL APPROACH Cellular assays and pharmacological models of RXFP1 activation were used to validate the potency and selectivity of R2R01. Increased renal blood flow was used as a translational marker of R2R01 activity. Human mastocytes (LAD2 cells) were used to study potential pseudo-allergic reactions and CD4+ T-cells to study immunogenicity. The pharmacokinetics of R2R01 were characterized in rats and minipigs. KEY RESULTS In vitro, R2R01 had comparable potency and efficacy to relaxin as an agonist for human RXFP1. In vivo, subcutaneous administration of R2R01 increased heart rate and renal blood flow in normotensive and hypertensive rat and did not show evidence of tachyphylaxis. R2R01 also increased nipple length in rats, used as a chronic model of RXFP1 engagement. Pharmacokinetic studies showed that R2R01 has a significantly extended terminal half-life. The in vitro assays with LAD2 cells and CD4+ T-cells showed that R2R01 had low potential for pseudo-allergic and immunogenic reactions, respectively. CONCLUSION AND IMPLICATIONS R2R01 is a potent RXFP1 agonist with an extended half-life that increases renal blood flow in various settings including normotensive and hypertensive conditions. The preclinical efficacy and safety data supported clinical development of R2R01 as a potential new therapy for renal and cardiovascular diseases.
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Affiliation(s)
- Bruno Poirier
- Cardio-Vascular and metabolism, Sanofi R&D, Chilly Mazarin, France
| | | | - Xavier Chenede
- Cardio-Vascular and metabolism, Sanofi R&D, Chilly Mazarin, France
| | - Alain Corbier
- Cardio-Vascular and metabolism, Sanofi R&D, Chilly Mazarin, France
| | - Philippe Prigent
- Cardio-Vascular and metabolism, Sanofi R&D, Chilly Mazarin, France
| | | | - Carine Bernard
- Cardio-Vascular and metabolism, Sanofi R&D, Chilly Mazarin, France
| | - Michel Guillotel
- Cardio-Vascular and metabolism, Sanofi R&D, Chilly Mazarin, France
| | - Florence Gillot
- Cardio-Vascular and metabolism, Sanofi R&D, Chilly Mazarin, France
| | - Laurence Riva
- Cardio-Vascular and metabolism, Sanofi R&D, Chilly Mazarin, France
| | - Veronique Briand
- Cardio-Vascular and metabolism, Sanofi R&D, Chilly Mazarin, France
| | - Raffaele Ingenito
- Peptides and Small Molecules R&D Department, IRBM Spa, Pomezia, Rome, Italy
| | - Laurence Gauzy-Lazo
- Département Médicaments et Technologies pour la Santé, Université de Paris-Saclay, CEA, INRAE, Gif-sur-Yvette, France
| | - Olivier Duclos
- Département Médicaments et Technologies pour la Santé, Université de Paris-Saclay, CEA, INRAE, Gif-sur-Yvette, France
| | | | | | - Elisabetta Bianchi
- Peptides and Small Molecules R&D Department, IRBM Spa, Pomezia, Rome, Italy
| | - Sergio Mallart
- Département Médicaments et Technologies pour la Santé, Université de Paris-Saclay, CEA, INRAE, Gif-sur-Yvette, France
| | - Philip Janiak
- Cardio-Vascular and metabolism, Sanofi R&D, Chilly Mazarin, France
| | - Stephane Illiano
- Cardio-Vascular and metabolism, Sanofi R&D, Chilly Mazarin, France
- Investigative Toxicology, Sanofi R&D, Chilly Mazarin, France
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2
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Gabris-Weber B, Forghani R, Bernd Dschietzig T, Romero G, Salama G. Periodic injections of Relaxin 2, its pharmacokinetics and remodeling of rat hearts. Biochem Pharmacol 2024; 223:116136. [PMID: 38494063 DOI: 10.1016/j.bcp.2024.116136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 03/12/2024] [Accepted: 03/14/2024] [Indexed: 03/19/2024]
Abstract
Relaxin-2 (RLX), a critical hormone in pregnancy, has been investigated as a therapy for heart failure. In most studies, the peptide was delivered continuously, subcutaneously for 2 weeks in animals or intravenously for 2-days in human subjects, for stable circulating [RLX]. However, pulsatile hormone levels may better uncover the normal physiology. This premise was tested by subcutaneously injecting Sprague Dawley rats (250 g, N = 2 males, 2 females/group) with human RLX (0, 30, 100, or 500 µg/kg), every 12 h for 1 day, then measuring changes in Nav1.5, connexin43, and β-catenin, 24 h later. Pulsatile RLX was measured by taking serial blood draws, post-injection. After an injection, RLX reached a peak in ∼ 60 min, fell to 50 % in 5-6 h; injections of 0, 30, 100 or 500 µg/kg yielded peak levels of 0, 11.26 ± 3.52, 58.33 ± 16.10, and 209.42 ± 29.04 ng/ml and residual levels after 24-hrs of 0, 4.9, 45.1 and 156 pg/ml, respectively. The 30 µg/kg injections had no effect and 100 µg/kg injections increased Nav1.5 (25 %), Cx43 (30 %) and β-catenin (90 %). The 500 µg/kg injections also increased Nav1.5 and Cx43 but were less effective at upregulating β-catenin (up by 25 % vs. 90 %). Periodic injections of 100 µg/kg were highly effective at increasing the expression of Nav1.5 and Cx43 which are key determinants of conduction velocity in the heart and the suppression of arrhythmias. Periodic RLX is effective at eliciting changes in cardiac protein expression and may be a better strategy for its longer-term delivery in the clinical setting.
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Affiliation(s)
- Beth Gabris-Weber
- University of Pittsburgh, School of Medicine, Department of Medicine, Heart and Vascular Medicine Institute, Pittsburgh, PA 15261, United States
| | - Rameen Forghani
- University of Pittsburgh, School of Medicine, Department of Medicine, Heart and Vascular Medicine Institute, Pittsburgh, PA 15261, United States
| | - Thomas Bernd Dschietzig
- Relaxera Pharmazeutische Gesellschaft mbH & Co. KG, Stubenwald-Allee 8a, 64625 Bensheim, Germany
| | - Guillermo Romero
- University of Pittsburgh, School of Medicine, Department of Medicine, Heart and Vascular Medicine Institute, Pittsburgh, PA 15261, United States; University of Pittsburgh, School of Medicine, Department of Pharmacology and Chemical Biology, Pittsburgh, PA 15261, United States
| | - Guy Salama
- University of Pittsburgh, School of Medicine, Department of Medicine, Heart and Vascular Medicine Institute, Pittsburgh, PA 15261, United States.
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3
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Alam F, Gaspari TA, Kemp-Harper BK, Low E, Aw A, Ferens D, Spizzo I, Jefferis AM, Praveen P, Widdop RE, Bathgate RAD, Hossain MA, Samuel CS. The single-chain relaxin mimetic, B7-33, maintains the cardioprotective effects of relaxin and more rapidly reduces left ventricular fibrosis compared to perindopril in an experimental model of cardiomyopathy. Biomed Pharmacother 2023; 160:114370. [PMID: 36753958 DOI: 10.1016/j.biopha.2023.114370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/30/2023] [Accepted: 02/03/2023] [Indexed: 02/09/2023] Open
Abstract
The hormone, relaxin (RLX), exerts various organ-protective effects independently of etiology. However, its complex two-chain and three disulphide bonded structure is a limitation to its preparation and affordability. Hence, a single chain-derivative of RLX, B7-33, was developed and shown to retain the anti-fibrotic effects of RLX in vitro and in vivo. Here, we determined whether B7-33 could retain the other cardioprotective effects of RLX, and also compared its therapeutic efficacy to the ACE inhibitor, perindopril. Adult male 129sv mice were subjected to isoprenaline (ISO; 25 mg/kg/day, s.c)-induced cardiomyopathy, then s.c-treated with either RLX (0.5 mg/kg/day), B7-33 (0.25 mg/kg/day; equivalent dose corrected for MW) or perindopril (1 mg/kg/day) from days 7-14 post-injury. Control mice received saline instead of ISO. Changes in animal body weight (BW) and systolic blood pressure (SBP) were measured weekly, whilst cardiomyocyte hypertrophy and measures of vascular dysfunction and rarefaction, left ventricular (LV) inflammation and fibrosis were assessed at day 14 post-injury. ISO-injured mice had significantly increased LV inflammation, cardiomyocyte hypertrophy, fibrosis, vascular rarefaction and aortic contractility in the absence of any changes in BW or SBP at day 14 post-injury. Both B7-33 and RLX equivalently reduced LV fibrosis and normalised the ISO-induced LV inflammation and cardiomyocyte hypertrophy, whilst restoring blood vessel density and aortic contractility. Comparatively, perindopril lowered SBP and the ISO-induced LV inflammation and vascular rarefaction, but not fibrosis or hypertrophy. As B7-33 retained the cardioprotective effects of RLX and provided rapid-occurring anti-fibrotic effects compared to perindopril, it could be considered as a cost-effective cardioprotective therapy.
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Affiliation(s)
- Fariha Alam
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia
| | - Tracey A Gaspari
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia
| | - Barbara K Kemp-Harper
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia
| | - Edward Low
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia
| | - Aaron Aw
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia
| | - Dorota Ferens
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia
| | - Iresha Spizzo
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia
| | - Ann-Maree Jefferis
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia
| | - Praveen Praveen
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia
| | - Robert E Widdop
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia
| | - Ross A D Bathgate
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia; Department of Biochemistry and Pharmacology, The University of Melbourne, Parkville, Victoria, Australia
| | - Mohammed Akhter Hossain
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia; School of Chemistry, The University of Melbourne, Parkville, Victoria, Australia.
| | - Chrishan S Samuel
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia; Department of Biochemistry and Pharmacology, The University of Melbourne, Parkville, Victoria, Australia.
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4
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Characterization of a new potent and long-lasting single chain peptide agonist of RXFP1 in cells and in vivo translational models. Sci Rep 2022; 12:20435. [PMID: 36443381 PMCID: PMC9705314 DOI: 10.1038/s41598-022-24716-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 11/18/2022] [Indexed: 11/29/2022] Open
Abstract
Despite beneficial effects in acute heart failure, the full therapeutic potential of recombinant relaxin-2 has been hampered by its short half-life and the need for intravenous administration limiting its use to intensive care units. A multiparametric optimization of the relaxin B-chain led to the identification of single chain lipidated peptide agonists of RXFP1 like SA10SC-RLX with subcutaneous bioavailability and extended half-life. SA10SC-RLX has sub nanomolar activity on cells expressing human RXFP1 and molecular modeling associated with the study of different RXFP1 mutants was used to decipher the mechanism of SA10SC-RLX interaction with RXFP1. Telemetry was performed in rat where SA10SC-RLX was able to engage RXFP1 after subcutaneous administration without tachyphylaxis after repeated dosing. Renal blood flow was then used as a translational model to evaluate RXFP1 activation. SA10SC-RLX increased renal blood flow and decreased renal vascular resistance in rats as reported for relaxin in humans. In conclusion, SA10SC-RLX mimics relaxin activity in in vitro and in vivo models of acute RXFP1 engagement. SA10SC-RLX represents a new class of long-lasting RXFP1 agonist, suitable for once daily subcutaneous administration in patients and potentially paving the way to new treatments for chronic fibrotic and cardiovascular diseases.
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Chunduri P, Patel SA, Levick SP. Relaxin/serelaxin for cardiac dysfunction and heart failure in hypertension. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2022; 94:183-211. [PMID: 35659372 DOI: 10.1016/bs.apha.2022.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The pregnancy related hormone relaxin is produced throughout the reproductive system. However, relaxin also has important cardiovascular effects as part of the adaptation that the cardiovascular system undergoes in response to the extra demands of pregnancy. These effects are primarily mediated by the relaxin family peptide receptor 1, which is one of four known relaxin receptors. The effects of relaxin on the cardiovascular system during pregnancy, as well as its anti-fibrotic and anti-inflammatory properties, have led to extensive studies into the potential of relaxin therapy as an approach to treat heart failure. Cardiomyocytes, cardiac fibroblasts, and endothelial cells all possess relaxin family peptide receptor 1, allowing for direct effects of therapeutic relaxin on the heart. Many pre-clinical animal studies have demonstrated a beneficial effect of exogenous relaxin on adverse cardiac remodeling including inflammation, fibrosis, cardiomyocyte hypertrophy and apoptosis, as well as effects on cardiac contractile function. Despite this, clinical studies have yielded disappointing results for the synthetic seralaxin, even though seralaxin was well tolerated. This article will provide background on relaxin in the context of normal physiology, as well as the role of relaxin in pregnancy-related adaptations of the cardiovascular system. We will also present evidence from pre-clinical animal studies that demonstrate the potential benefits of relaxin therapy, as well as discussing the results from clinical trials. Finally, we will discuss possible reasons for the failure of these clinical trials as well as steps being taken to potentially improve relaxin therapy for heart failure.
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Affiliation(s)
- Prasad Chunduri
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Shrey A Patel
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Scott P Levick
- Physiology and Pharmacology, West Virginia University, Morgantown, WV, United States.
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6
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Long V, Mathieu S, Fiset C. Pregnancy-induced increased heart rate is independent of thyroid hormones. Heart Rhythm O2 2021; 2:168-173. [PMID: 34113919 PMCID: PMC8183852 DOI: 10.1016/j.hroo.2021.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Background The heart rate increases by 10–20 beats per minute (bpm) throughout pregnancy in women, reaching maximum heart rate in the third trimester. During pregnancy, important changes in thyroid hormones also occur, with increases of up to 50% in the levels of triiodothyronine (T3), the biological active thyroid hormone. In addition, T3 has been shown to regulate cardiac electrophysiology. Objective Thus, in the present study the potential contribution of T3 in pregnancy-induced increased heart rate was explored. Methods We compared the heart rate between nonpregnant and pregnant mice under control conditions and after altering thyroid hormone levels with T3 and propylthiouracil (PTU, an antithyroid drug) treatments. Results Consistent with the clinical data, we found a 58% rise in T3 levels during pregnancy in mice. Although pregnant mice had a higher baseline heart rate (607 ± 8 bpm, P = .004) and higher T3 levels (1.9 ± 0.4 nM, P = .0005) than nonpregnant mice (heart rate: 546 ± 16 bpm; T3 levels: 1.2 ± 0.1 nM), their heart rate responded similarly to T3 treatment as nonpregnant mice (nonpregnant: Δ130 ± 22 bpm; pregnant: Δ126 ± 17 bpm, P = .858). Additionally, the heart rate remained significantly elevated (607 ± 11 bpm, P = .038) and comparable to untreated pregnant mice, after the use of the antithyroid drug PTU, although T3 levels (1.3 ± 0.2 nM, P = .559) returned to nonpregnant values. Conclusion Based on these results, it is unlikely that T3 contributes significantly to the pregnancy-induced increased heart rate.
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Affiliation(s)
- Valérie Long
- Research Center, Montreal Heart Institute, Montreal, Canada.,Faculty of Pharmacy, Université de Montréal, Montreal, Canada
| | - Sophie Mathieu
- Research Center, Montreal Heart Institute, Montreal, Canada.,Faculty of Pharmacy, Université de Montréal, Montreal, Canada
| | - Céline Fiset
- Research Center, Montreal Heart Institute, Montreal, Canada.,Faculty of Pharmacy, Université de Montréal, Montreal, Canada
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7
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Romero G, Salama G. Relaxin abrogates genomic remodeling of the aged heart. VITAMINS AND HORMONES 2021; 115:419-448. [PMID: 33706957 DOI: 10.1016/bs.vh.2020.12.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
"Healthy" aging drives structural and functional changes in the heart including maladaptive electrical remodeling, fibrosis and inflammation, which lower the threshold for cardiovascular diseases such as heart failure (HF) and atrial fibrillation (AF). Despite mixed results in clinical trials, Relaxin-therapy for 2-days reduced mortality by 37% at 180-days post-treatment, in patients with acute decompensated HF. Relaxin's short lifespan (2-3h) but long-lasting protective actions suggested that relaxin acts at a genomic level to reverse maladaptive remodeling in AF, HF and aging. Our recent studies showed that a 2-week treatment with Relaxin (0.4mg/kg/day) of aged (24months old F-344 rats) increases the expression of voltage-gated Na+ channels (mRNA, Nav1.5 and INa), connexin-43, abrogates inflammatory and immune responses and reverses myocardial fibrosis and cellular hypertrophy of the aged hearts. Relaxin acts directly at a wide range of cell types in the cardiovascular system that express its cognate GPCR receptor, RXFP1. RNA-seq analysis of young and aged hearts with and without Relaxin treatment revealed that "normal" aging altered the expression of ~10% of genes expressed in the ventricles, including: ion channels, components of fibrosis, hemodynamic biomarkers, immune and inflammatory responses which were reversed by Relaxin. The extensive cardiovascular remodeling caused by Relaxin was mediated through the activation of the Wnt/β-catenin signaling pathway which was otherwise suppressed by in adult cardiomyocytes intracellular by cytosolic Dickkopf1 (Dkk1). Wnt/β-catenin signaling is a mechanism that can explain the pleiotropic actions of Relaxin and the marked reversal of genomic changes that occur in aged hearts.
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Affiliation(s)
- Guillermo Romero
- Department of Pharmacology & Chemical Biology, University of Pittsburgh, Pittsburgh, PA, United States.
| | - Guy Salama
- Department of Medicine, Heart and Vascular Institute, University of Pittsburgh, Pittsburgh, PA, United States
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MacDonald EA, Rose RA, Quinn TA. Neurohumoral Control of Sinoatrial Node Activity and Heart Rate: Insight From Experimental Models and Findings From Humans. Front Physiol 2020; 11:170. [PMID: 32194439 PMCID: PMC7063087 DOI: 10.3389/fphys.2020.00170] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 02/13/2020] [Indexed: 12/22/2022] Open
Abstract
The sinoatrial node is perhaps one of the most important tissues in the entire body: it is the natural pacemaker of the heart, making it responsible for initiating each-and-every normal heartbeat. As such, its activity is heavily controlled, allowing heart rate to rapidly adapt to changes in physiological demand. Control of sinoatrial node activity, however, is complex, occurring through the autonomic nervous system and various circulating and locally released factors. In this review we discuss the coupled-clock pacemaker system and how its manipulation by neurohumoral signaling alters heart rate, considering the multitude of canonical and non-canonical agents that are known to modulate sinoatrial node activity. For each, we discuss the principal receptors involved and known intracellular signaling and protein targets, highlighting gaps in our knowledge and understanding from experimental models and human studies that represent areas for future research.
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Affiliation(s)
- Eilidh A MacDonald
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Robert A Rose
- Cumming School of Medicine, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada.,School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
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9
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Martin B, Romero G, Salama G. Cardioprotective actions of relaxin. Mol Cell Endocrinol 2019; 487:45-53. [PMID: 30625345 DOI: 10.1016/j.mce.2018.12.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 12/20/2018] [Accepted: 12/22/2018] [Indexed: 01/19/2023]
Abstract
Relaxin is a hormone of pregnancy first discovered for its ability to induce ligament relaxation in nonpregnant guinea pig and is important for softening of the birth canal during parturition, decidualization, implantation, nipple development and increased maternal renal perfusion, glomerular filtration, and cardiac output. Subsequently, relaxin has been shown to exert multiple beneficial cardiovascular effects during pathological events such as hypertension, atrial fibrillation, heart failure and myocardial infarction, including suppression of arrhythmia and inflammation, and reversal of fibrosis. Despite extensive studies, the mechanisms underlying relaxin's effects are not well understood. Relaxin signals primarily through its G protein coupled receptor, the relaxin family peptide receptor-1, to activate multiple signaling pathways and this review summarizes our understanding of these pathways as they relate to the cardioprotective actions of relaxin, focusing on relaxin's anti-fibrotic, anti-arrhythmic and anti-inflammatory properties. Further, this review includes a brief overview of relaxin in clinical trials for heart failure and progress in the development of relaxin mimetics.
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Affiliation(s)
- Brian Martin
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, 15261, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Guillermo Romero
- Department of Pharmacology & Chemical Biology, University of Pittsburgh, Pittsburgh, PA, 15261, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Guy Salama
- Department of Medicine, Heart and Vascular Institute, University of Pittsburgh, Pittsburgh, PA, 15261, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, 15261, USA.
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10
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Pawlicki P, Hejmej A, Milon A, Lustofin K, Płachno BJ, Tworzydlo W, Gorowska-Wojtowicz E, Pawlicka B, Kotula-Balak M, Bilinska B. Telocytes in the mouse testicular interstitium: implications of G-protein-coupled estrogen receptor (GPER) and estrogen-related receptor (ERR) in the regulation of mouse testicular interstitial cells. PROTOPLASMA 2019; 256:393-408. [PMID: 30187340 PMCID: PMC6510843 DOI: 10.1007/s00709-018-1305-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 08/24/2018] [Indexed: 05/12/2023]
Abstract
Telocytes (TCs), a novel type of interstitial cells, are involved in tissue homeostasis maintenance. This study aimed to investigate TC presence in the interstitium of mouse testis. Additionally, inactivation of the G-coupled membrane estrogen receptor (GPER) in the testis was performed to obtain insight into TC function, regulation, and interaction with other interstitial cells. Mice were injected with a GPER antagonist (G-15; 50 μg/kg bw), and the GPER-signaling effect on TC distribution, ultrastructure, and function, as well as the interstitial tissue interaction of GPER with estrogen-related receptors (ERRs), was examined. Microscopic observations of TC morphology were performed with the use of scanning and transmission electron microscopes. Telocyte functional markers (CD34; c-kit; platelet-derived growth factor receptors α and β, PDGFRα and β; vascular endothelial growth factor, VEGF; and vimentin) were analyzed by immunohistochemistry/immunofluorescence and Western blot. mRNA expression of CD34 as well as ERR α, β, and γ was measured by qRT-PCR. Relaxin and Ca2+ concentrations were analyzed by immunoenzymatic and colorimetric assays, respectively. For the first time, we reveal the presence of TCs in the interstitium together with the peritubular area of mouse testis. Telocytes were characterized by specific features such as a small cell body and extremely long prolongations, constituting a three-dimensional network mainly around the interstitial cells. Expression of all TC protein markers was confirmed. Based on scanning electron microscopic observation in GPER-blocked testis, groups of TCs were frequently seen. No changes were found in TC ultrastructure in GPER-blocked testis when compared to the control. However, tendency to TC number change (increase) after the blockage was observed. Concomitantly, no changes in mRNA CD34 expression and increase in ERR expression were detected in GPER-blocked testes. In addition, Ca2+ was unchanged; however, an increase in relaxin concentration was observed. Telocytes are an important component of the mouse testicular interstitium, possibly taking part in maintaining its microenvironment as well as contractile and secretory functions (via themselves or via controlling of other interstitial cells). These cells should be considered a unique and useful target cell type for the prevention and treatment of testicular interstitial tissue disorders based on estrogen-signaling disturbances.
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Affiliation(s)
- Piotr Pawlicki
- Department of Endocrinology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - Anna Hejmej
- Department of Endocrinology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - Agnieszka Milon
- Department of Endocrinology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - Krzysztof Lustofin
- Department of Endocrinology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - Bartosz J Płachno
- Department of Plant Cytology and Embryology, Institute of Botany, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - Waclaw Tworzydlo
- Department of Developmental Biology and Invertebrate Morphology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - Ewelina Gorowska-Wojtowicz
- Department of Endocrinology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - Bernadetta Pawlicka
- Department of Genetics and Evolution, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
| | - Malgorzata Kotula-Balak
- Department of Endocrinology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland.
| | - Barbara Bilinska
- Department of Endocrinology, Institute of Zoology and Biomedical Research, Jagiellonian University in Kraków, Gronostajowa 9, 30-387, Krakow, Poland
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Ikeda Y, Zabbarova IV, Birder LA, Wipf P, Getchell SE, Tyagi P, Fry CH, Drake MJ, Kanai AJ. Relaxin-2 therapy reverses radiation-induced fibrosis and restores bladder function in mice. Neurourol Urodyn 2018; 37:2441-2451. [PMID: 29806709 PMCID: PMC6202145 DOI: 10.1002/nau.23721] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 05/09/2018] [Indexed: 12/27/2022]
Abstract
AIM To determine the efficacy of human relaxin-2 (hRLX2) in reversing radiation-induced bladder fibrosis and lower urinary tract dysfunction (LUTD). Radiation cystitis is a consequence of radiotherapy for pelvic malignancies. Acutely, irradiation leads to reactive oxygen/nitrogen species in urothelial cells, apoptosis, barrier disruption, and inflammation. Chronically, this results in collagen deposition, bladder fibrosis, and attenuated storage and voiding functions. In severe cases, cystectomies are performed as current therapies do not reverse fibrosis. METHODS We developed a mouse model for selective bladder irradiation (10 Gray; 1 Gy = 100 rads) resulting in chronic fibrosis within 6 weeks, with decreased bladder compliance, contractility, and overflow incontinence. Seven weeks post-irradiation, female C57Bl/6 mice were continuously infused with hRLX2 (400 μg/kg/day/14 days) or vehicle (saline) via subcutaneous osmotic pumps. Mice were evaluated in vivo using urine spot analysis, cystometrograms and external urethral sphincter electromyograms; and in vitro using length-tension measurements, Western blots, histology, and immunohistochemistry. RESULTS hRLX2 reversed fibrosis, decreased collagen content, improved bladder wall architecture, and increased bladder compliance, detrusor smooth muscle Cav1.2 expression and detrusor contractility in mice with chronic radiation cystitis. hRLX2 treatment outcomes were likely caused by the activation of RXFP1/2 receptors which are expressed on the detrusor. CONCLUSION hRLX2 may be a new therapeutic option for rescuing bladders with chronic radiation cystitis.
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Affiliation(s)
- Youko Ikeda
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Irina V. Zabbarova
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Lori A. Birder
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania,Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Peter Wipf
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Samuel E. Getchell
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Pradeep Tyagi
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Christopher H. Fry
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Marcus J. Drake
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Anthony J. Kanai
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania,Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
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Beiert T, Knappe V, Tiyerili V, Stöckigt F, Effelsberg V, Linhart M, Steinmetz M, Klein S, Schierwagen R, Trebicka J, Roell W, Nickenig G, Schrickel JW, Andrié RP. Chronic lower-dose relaxin administration protects from arrhythmia in experimental myocardial infarction due to anti-inflammatory and anti-fibrotic properties. Int J Cardiol 2018; 250:21-28. [DOI: 10.1016/j.ijcard.2017.09.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 08/30/2017] [Accepted: 09/06/2017] [Indexed: 12/11/2022]
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Feijóo-Bandín S, Aragón-Herrera A, Rodríguez-Penas D, Portolés M, Roselló-Lletí E, Rivera M, González-Juanatey JR, Lago F. Relaxin-2 in Cardiometabolic Diseases: Mechanisms of Action and Future Perspectives. Front Physiol 2017; 8:599. [PMID: 28868039 PMCID: PMC5563388 DOI: 10.3389/fphys.2017.00599] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 08/03/2017] [Indexed: 12/13/2022] Open
Abstract
Despite the great effort of the medical community during the last decades, cardiovascular diseases remain the leading cause of death worldwide, increasing their prevalence every year mainly due to our new way of life. In the last years, the study of new hormones implicated in the regulation of energy metabolism and inflammation has raised a great interest among the scientific community regarding their implications in the development of cardiometabolic diseases. In this review, we will summarize the main actions of relaxin, a pleiotropic hormone that was previously suggested to improve acute heart failure and that participates in both metabolism and inflammation regulation at cardiovascular level, and will discuss its potential as future therapeutic target to prevent/reduce cardiovascular diseases.
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Affiliation(s)
- Sandra Feijóo-Bandín
- Cellular and Molecular Cardiology Research Unit, Institute of Biomedical Research and University Clinical HospitalSantiago de Compostela, Spain
- Centro de Investigación Biomédica en Red de Enfermedades CardiovascularesMadrid, Spain
| | - Alana Aragón-Herrera
- Cellular and Molecular Cardiology Research Unit, Institute of Biomedical Research and University Clinical HospitalSantiago de Compostela, Spain
| | - Diego Rodríguez-Penas
- Cellular and Molecular Cardiology Research Unit, Institute of Biomedical Research and University Clinical HospitalSantiago de Compostela, Spain
| | - Manuel Portolés
- Centro de Investigación Biomédica en Red de Enfermedades CardiovascularesMadrid, Spain
- Cardiocirculatory Unit, Health Research Institute of La Fe University HospitalValencia, Spain
| | - Esther Roselló-Lletí
- Centro de Investigación Biomédica en Red de Enfermedades CardiovascularesMadrid, Spain
- Cardiocirculatory Unit, Health Research Institute of La Fe University HospitalValencia, Spain
| | - Miguel Rivera
- Centro de Investigación Biomédica en Red de Enfermedades CardiovascularesMadrid, Spain
- Cardiocirculatory Unit, Health Research Institute of La Fe University HospitalValencia, Spain
| | - José R. González-Juanatey
- Cellular and Molecular Cardiology Research Unit, Institute of Biomedical Research and University Clinical HospitalSantiago de Compostela, Spain
- Centro de Investigación Biomédica en Red de Enfermedades CardiovascularesMadrid, Spain
| | - Francisca Lago
- Cellular and Molecular Cardiology Research Unit, Institute of Biomedical Research and University Clinical HospitalSantiago de Compostela, Spain
- Centro de Investigación Biomédica en Red de Enfermedades CardiovascularesMadrid, Spain
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14
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Sarwar M, Du XJ, Dschietzig TB, Summers RJ. The actions of relaxin on the human cardiovascular system. Br J Pharmacol 2016; 174:933-949. [PMID: 27239943 DOI: 10.1111/bph.13523] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 04/01/2016] [Accepted: 04/26/2016] [Indexed: 12/14/2022] Open
Abstract
The insulin-like peptide relaxin, originally identified as a hormone of pregnancy, is now known to exert a range of pleiotropic effects including vasodilatory, anti-fibrotic, angiogenic, anti-apoptotic and anti-inflammatory effects in both males and females. Relaxin produces these effects by binding to a cognate receptor RXFP1 and activating a variety of signalling pathways including cAMP, cGMP and MAPKs as well as by altering gene expression of TGF-β, MMPs, angiogenic growth factors and endothelin receptors. The peptide has been shown to be effective in halting or reversing many of the adverse effects including fibrosis in animal models of cardiovascular disease including ischaemia/reperfusion injury, myocardial infarction, hypertensive heart disease and cardiomyopathy. Relaxin given to humans is safe and produces favourable haemodynamic changes. Serelaxin, the recombinant form of relaxin, is now in extended phase III clinical trials for the treatment of acute heart failure. Previous clinical studies indicated that a 48 h infusion of relaxin improved 180 day mortality, yet the mechanism underlying this effect is not clear. This article provides an overview of the cellular mechanism of effects of relaxin and summarizes its beneficial actions in animal models and in the clinic. We also hypothesize potential mechanisms for the clinical efficacy of relaxin, identify current knowledge gaps and suggest new ways in which relaxin could be useful therapeutically. LINKED ARTICLES This article is part of a themed section on Recent Progress in the Understanding of Relaxin Family Peptides and their Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.10/issuetoc.
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Affiliation(s)
- Mohsin Sarwar
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Australia
| | - Xiao-Jun Du
- Baker IDI Heart and Diabetes Institute, Melbourne, Australia
| | - Thomas B Dschietzig
- Immundiagnostik AG, Bensheim, Germany.,Campus Mitte, Medical Clinic for Cardiology and Angiology, Charité-University Medicine Berlin, Berlin, Germany.,Relaxera Pharmazeutische Gesellschaft mbH & Co. KG, Bensheim, Germany
| | - Roger J Summers
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Australia
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15
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Díez J, Ruilope LM. Serelaxin for the treatment of acute heart failure: a review with a focus on end-organ protection. EUROPEAN HEART JOURNAL. CARDIOVASCULAR PHARMACOTHERAPY 2015; 2:119-30. [PMID: 27418970 PMCID: PMC4853824 DOI: 10.1093/ehjcvp/pvv046] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 10/26/2015] [Indexed: 12/15/2022]
Abstract
Acute heart failure (AHF) is a complex clinical syndrome characterized by fluid overload and haemodynamic abnormalities (short-term clinical consequences) and the development of end-organ damage (long-term consequences). Current therapies for the treatment of AHF, such as loop diuretics and vasodilators, help to relieve haemodynamic imbalance and congestion, but have not been shown to prevent (and may even contribute to) end-organ damage, or to provide long-term clinical benefit. Serelaxin is the recombinant form of human relaxin-2, a naturally occurring hormone involved in mediating haemodynamic changes during pregnancy. Preclinical and clinical studies have investigated the effects mediated by serelaxin and the suitability of this agent for the treatment of patients with AHF. Data suggest that serelaxin acts via multiple pathways to improve haemodynamics at the vascular, cardiac, and renal level and provide effective congestion relief. In addition, this novel agent may protect the heart, kidneys, and liver from damage by inhibiting inflammation, oxidative stress, cell death, and tissue fibrosis, and stimulating angiogenesis. Serelaxin may therefore improve both short- and long-term outcomes in patients with AHF. In this review, we examine the unique mechanisms underlying the potential benefits of serelaxin for the treatment of AHF, in particular, those involved in mediating end-organ protection.
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Affiliation(s)
- Javier Díez
- Program of Cardiovascular Diseases, Centre for Applied Medical Research and Department of Cardiology and Cardiac Surgery, University of Navarra Clinic, University of Navarra, Av. Pío XII 55, Pamplona 31008, Spain
| | - Luis M Ruilope
- Research Institute, Hypertension Unit, Hospital 12 de Octubre and Department of Public Health and Preventive Medicine, University Autónoma, Madrid, Spain
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16
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Halls ML, Bathgate RAD, Sutton SW, Dschietzig TB, Summers RJ. International Union of Basic and Clinical Pharmacology. XCV. Recent advances in the understanding of the pharmacology and biological roles of relaxin family peptide receptors 1-4, the receptors for relaxin family peptides. Pharmacol Rev 2015; 67:389-440. [PMID: 25761609 DOI: 10.1124/pr.114.009472] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Relaxin, insulin-like peptide 3 (INSL3), relaxin-3, and INSL5 are the cognate ligands for the relaxin family peptide (RXFP) receptors 1-4, respectively. RXFP1 activates pleiotropic signaling pathways including the signalosome protein complex that facilitates high-sensitivity signaling; coupling to Gα(s), Gα(i), and Gα(o) proteins; interaction with glucocorticoid receptors; and the formation of hetero-oligomers with distinctive pharmacological properties. In addition to relaxin-related ligands, RXFP1 is activated by Clq-tumor necrosis factor-related protein 8 and by small-molecular-weight agonists, such as ML290 [2-isopropoxy-N-(2-(3-(trifluoromethylsulfonyl)phenylcarbamoyl)phenyl)benzamide], that act allosterically. RXFP2 activates only the Gα(s)- and Gα(o)-coupled pathways. Relaxin-3 is primarily a neuropeptide, and its cognate receptor RXFP3 is a target for the treatment of depression, anxiety, and autism. A variety of peptide agonists, antagonists, biased agonists, and an allosteric modulator target RXFP3. Both RXFP3 and the related RXFP4 couple to Gα(i)/Gα(o) proteins. INSL5 has the properties of an incretin; it is secreted from the gut and is orexigenic. The expression of RXFP4 in gut, adipose tissue, and β-islets together with compromised glucose tolerance in INSL5 or RXFP4 knockout mice suggests a metabolic role. This review focuses on the many advances in our understanding of RXFP receptors in the last 5 years, their signal transduction mechanisms, the development of novel compounds that target RXFP1-4, the challenges facing the field, and current prospects for new therapeutics.
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Affiliation(s)
- Michelle L Halls
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.L.H., R.J.S.); Neuropeptides Division, Florey Institute of Neuroscience and Mental Health and Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia (R.A.D.B.); Neuroscience Drug Discovery, Janssen Research & Development, LLC, San Diego, California (S.W.S.); Immundiagnostik AG, Bensheim, Germany (T.B.D.); and Charité-University Medicine Berlin, Campus Mitte, Medical Clinic for Cardiology and Angiology, Berlin, Germany (T.B.D.)
| | - Ross A D Bathgate
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.L.H., R.J.S.); Neuropeptides Division, Florey Institute of Neuroscience and Mental Health and Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia (R.A.D.B.); Neuroscience Drug Discovery, Janssen Research & Development, LLC, San Diego, California (S.W.S.); Immundiagnostik AG, Bensheim, Germany (T.B.D.); and Charité-University Medicine Berlin, Campus Mitte, Medical Clinic for Cardiology and Angiology, Berlin, Germany (T.B.D.)
| | - Steve W Sutton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.L.H., R.J.S.); Neuropeptides Division, Florey Institute of Neuroscience and Mental Health and Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia (R.A.D.B.); Neuroscience Drug Discovery, Janssen Research & Development, LLC, San Diego, California (S.W.S.); Immundiagnostik AG, Bensheim, Germany (T.B.D.); and Charité-University Medicine Berlin, Campus Mitte, Medical Clinic for Cardiology and Angiology, Berlin, Germany (T.B.D.)
| | - Thomas B Dschietzig
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.L.H., R.J.S.); Neuropeptides Division, Florey Institute of Neuroscience and Mental Health and Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia (R.A.D.B.); Neuroscience Drug Discovery, Janssen Research & Development, LLC, San Diego, California (S.W.S.); Immundiagnostik AG, Bensheim, Germany (T.B.D.); and Charité-University Medicine Berlin, Campus Mitte, Medical Clinic for Cardiology and Angiology, Berlin, Germany (T.B.D.)
| | - Roger J Summers
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.L.H., R.J.S.); Neuropeptides Division, Florey Institute of Neuroscience and Mental Health and Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia (R.A.D.B.); Neuroscience Drug Discovery, Janssen Research & Development, LLC, San Diego, California (S.W.S.); Immundiagnostik AG, Bensheim, Germany (T.B.D.); and Charité-University Medicine Berlin, Campus Mitte, Medical Clinic for Cardiology and Angiology, Berlin, Germany (T.B.D.)
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17
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Neschadim A, Summerlee AJS, Silvertown JD. Targeting the relaxin hormonal pathway in prostate cancer. Int J Cancer 2014; 137:2287-95. [PMID: 25043063 DOI: 10.1002/ijc.29079] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Accepted: 07/07/2014] [Indexed: 11/11/2022]
Abstract
Targeting the androgen signalling pathway has long been the hallmark of anti-hormonal therapy for prostate cancer. However, development of androgen-independent prostate cancer is an inevitable outcome to therapies targeting this pathway, in part, owing to the shift from cancer dependence on androgen signalling for growth in favor of augmentation of other cellular pathways that provide proliferation-, survival- and angiogenesis-promoting signals. This review focuses on the role of the hormone relaxin in the development and progression of prostate cancer, prior to and after the onset of androgen independence, as well as its role in cancers of other reproductive tissues. As the body of literature expands, examining relaxin expression in cancerous tissues and its role in a growing number of in vitro and in vivo cancer models, our understanding of the important involvement of this hormone in cancer biology is becoming clearer. Specifically, the pleiotropic functions of relaxin affecting cell growth, angiogenesis, blood flow, cell migration and extracellular matrix remodeling are examined in the context of cancer progression. The interactions and intercepts of the intracellular signalling pathways of relaxin with the androgen pathway are explored in the context of progression of castration-resistant and androgen-independent prostate cancers. We provide an overview of current anti-hormonal therapeutic treatment options for prostate cancer and delve into therapeutic approaches and development of agents aimed at specifically antagonizing relaxin signalling to curb tumor growth. We also discuss the rationale and challenges utilizing such agents as novel anti-hormonals in the clinic, and their potential to supplement current therapeutic modalities.
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Affiliation(s)
- Anton Neschadim
- Armour Therapeutics Inc., Toronto, 124 Orchard View Blvd, Toronto, ON, Canada
| | | | - Joshua D Silvertown
- Armour Therapeutics Inc., Toronto, 124 Orchard View Blvd, Toronto, ON, Canada
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18
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Zhao Z, Ng CY, Liu T, Li H, Li G. Relaxin as novel strategy in the management of atrial fibrillation: potential roles and future perspectives. Int J Cardiol 2013; 171:e72-3. [PMID: 24373631 DOI: 10.1016/j.ijcard.2013.11.103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Accepted: 11/30/2013] [Indexed: 01/09/2023]
Affiliation(s)
- Zhiqiang Zhao
- Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China
| | - Chee Yuan Ng
- Department of Cardiology, Loma Linda University Medical Center, CA, United States
| | - Tong Liu
- Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China
| | - Hongmin Li
- Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China
| | - Guangping Li
- Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, People's Republic of China.
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19
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Bathgate RAD, Halls ML, van der Westhuizen ET, Callander GE, Kocan M, Summers RJ. Relaxin family peptides and their receptors. Physiol Rev 2013; 93:405-80. [PMID: 23303914 DOI: 10.1152/physrev.00001.2012] [Citation(s) in RCA: 371] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
There are seven relaxin family peptides that are all structurally related to insulin. Relaxin has many roles in female and male reproduction, as a neuropeptide in the central nervous system, as a vasodilator and cardiac stimulant in the cardiovascular system, and as an antifibrotic agent. Insulin-like peptide-3 (INSL3) has clearly defined specialist roles in male and female reproduction, relaxin-3 is primarily a neuropeptide involved in stress and metabolic control, and INSL5 is widely distributed particularly in the gastrointestinal tract. Although they are structurally related to insulin, the relaxin family peptides produce their physiological effects by activating a group of four G protein-coupled receptors (GPCRs), relaxin family peptide receptors 1-4 (RXFP1-4). Relaxin and INSL3 are the cognate ligands for RXFP1 and RXFP2, respectively, that are leucine-rich repeat containing GPCRs. RXFP1 activates a wide spectrum of signaling pathways to generate second messengers that include cAMP and nitric oxide, whereas RXFP2 activates a subset of these pathways. Relaxin-3 and INSL5 are the cognate ligands for RXFP3 and RXFP4 that are closely related to small peptide receptors that when activated inhibit cAMP production and activate MAP kinases. Although there are still many unanswered questions regarding the mode of action of relaxin family peptides, it is clear that they have important physiological roles that could be exploited for therapeutic benefit.
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Affiliation(s)
- R A D Bathgate
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology, Monash University, Victoria, Australia
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20
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Abstract
The heart automaticity is a fundamental physiological function in higher organisms. The spontaneous activity is initiated by specialized populations of cardiac cells generating periodical electrical oscillations. The exact cascade of steps initiating the pacemaker cycle in automatic cells has not yet been entirely elucidated. Nevertheless, ion channels and intracellular Ca(2+) signaling are necessary for the proper setting of the pacemaker mechanism. Here, we review the current knowledge on the cellular mechanisms underlying the generation and regulation of cardiac automaticity. We discuss evidence on the functional role of different families of ion channels in cardiac pacemaking and review recent results obtained on genetically engineered mouse strains displaying dysfunction in heart automaticity. Beside ion channels, intracellular Ca(2+) release has been indicated as an important mechanism for promoting automaticity at rest as well as for acceleration of the heart rate under sympathetic nerve input. The potential links between the activity of ion channels and Ca(2+) release will be discussed with the aim to propose an integrated framework of the mechanism of automaticity.
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Affiliation(s)
- Matteo E Mangoni
- Institute of Functional Genomics, Department of Physiology, Centre National de la Recherche Scientifique UMR5203, INSERM U661, University of Montpellier I and II, Montpellier, France.
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Dschietzig T, Bartsch C, Baumann G, Stangl K. Relaxin—a pleiotropic hormone and its emerging role for experimental and clinical therapeutics. Pharmacol Ther 2006; 112:38-56. [PMID: 16647137 DOI: 10.1016/j.pharmthera.2006.03.004] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Accepted: 03/08/2006] [Indexed: 01/30/2023]
Abstract
The insulin-related peptide hormone relaxin (Rlx) is known as pregnancy hormone for decades. In the 1980s, researchers began to recognize the highly intriguing fact that Rlx plays a role in a multitude of physiological processes far beyond pregnancy and reproduction. So, Rlx's contribution to the regulation of vasotonus, plasma osmolality, angiogenesis, collagen turnover, and renal function has been established. In addition, the peptide has been demonstrated to represent a mediator of cardiovascular pathology. The ongoing efforts to identify Rlx receptors eventually precipitated the discovery of the G protein-coupled receptors (GPCR) LGR7 and LGR8 as membrane receptors for human Rlx-2 in 2002. This review will summarize the current state of insight into this rapidly evolving field, which has further been expanded by the discovery of GPCR135 and GPCR142 as receptors for Rlx-3. In addition, Rlx has also been shown to activate the human glucocorticoid receptor (GR). There is evidence from Rlx and Rlx receptor knockouts suggesting that LGR7 is the only relevant receptor for mouse Rlx-1 (corresponding to human Rlx-2) in vivo and that insulin-like peptide (INSL)-3 represents the physiological ligand for LGR8. Regarding Rlx signal transduction, the cyclic adenosine monophosphate (cAMP) and nitric oxide (NO) pathways will be characterized as major cascades. Investigation of downstream signaling remains an important field for future research. Finally, the current state of therapeutical strategies using Rlx in animal models as well as in humans is summarized.
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Affiliation(s)
- Thomas Dschietzig
- Medizinische Klinik m. S. Kardiologie und Angiologie, Charité-Universitätsmedizin Berlin, Campus Mitte, Schumannstr. 20/21, 10117 Berlin, Germany.
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22
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Samuel CS, Du XJ, Bathgate RAD, Summers RJ. 'Relaxin' the stiffened heart and arteries: the therapeutic potential for relaxin in the treatment of cardiovascular disease. Pharmacol Ther 2006; 112:529-52. [PMID: 16814863 DOI: 10.1016/j.pharmthera.2005.05.012] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2005] [Accepted: 05/15/2005] [Indexed: 12/20/2022]
Abstract
Although originally characterised as a reproductive hormone, relaxin has emerged as a multi-functional endocrine and paracrine factor that plays a number of important roles in several organs, including the normal and diseased cardiovascular system. The recent discovery of the H3/relaxin-3 gene, and the elusive receptors for relaxin (Relaxin family peptide receptor; RXFP1) and relaxin-3 (RXFP3/RXFP4) have led to the re-classification of a distinct relaxin peptide/receptor family. Additionally, the identification of relaxin and RXFP1 mRNA and/or relaxin binding sites in the heart and blood vessels has confirmed that the cardiovascular system is a target for relaxin peptides. While evidence for the production of relaxins within the cardiovascular system is limited, several studies have established that the relaxin genes are upregulated in the diseased human and rodent heart where they likely act as cardioprotective agents. The ability of relaxin to protect the heart is most likely mediated via its antifibrotic, anti-hypertrophic, anti-inflammatory and vasodilatory actions, but it may also directly stimulate myocardial regeneration and repair. This review describes relaxin and its primary receptor (RXFP1) in relation to the roles and effects of relaxin in the normal and pathological cardiovascular system. It is becoming increasingly clear that relaxin has a number of diverse physiological and pathological roles in the cardiovascular system that may have important therapeutic and clinical implications.
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Affiliation(s)
- Chrishan S Samuel
- Howard Florey Institute, University of Melbourne, Victoria 3010, Australia; Department of Biochemistry and Molecular Biology, University of Melbourne, Victoria 3010, Australia
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Bathgate RA, Ivell R, Sanborn BM, Sherwood OD, Summers RJ. International Union of Pharmacology LVII: recommendations for the nomenclature of receptors for relaxin family peptides. Pharmacol Rev 2006; 58:7-31. [PMID: 16507880 DOI: 10.1124/pr.58.1.9] [Citation(s) in RCA: 251] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Although the hormone relaxin was discovered 80 years ago, only in the past 5 years have the receptors for relaxin and three other receptors that respond to related peptides been identified with all four receptors being G-protein-coupled receptors. In this review it is suggested that the receptors for relaxin (LGR7) and those for the related peptides insulin-like peptide 3 (LGR8), relaxin-3 (GPCR135), and insulin-like peptide 5 (LGPCR142) be named the relaxin family peptide receptors 1 through 4 (RXFP1-4). RXFP1 and RXFP2 are leucine-rich repeat-containing G-protein-coupled receptors with complex binding characteristics involving both the large ectodomain and the transmembrane loops. RXFP1 activates adenylate cyclase, protein kinase A, protein kinase C, phosphatidylinositol 3-kinase, and extracellular signaling regulated kinase (Erk1/2) and also interacts with nitric oxide signaling. RXFP2 activates adenylate cyclase in recombinant systems, but physiological responses are sensitive to pertussis toxin. RXFP3 and RXFP4 resemble more conventional peptide liganded receptors and both inhibit adenylate cyclase, and in addition RXFP3 activates Erk1/2 signaling. Physiological studies and examination of the phenotypes of transgenic mice have established that relaxin has roles as a reproductive hormone involved in uterine relaxation (some species), reproductive tissue growth, and collagen remodeling but also in the cardiovascular and renal systems and in the brain. The connective tissue remodeling properties of relaxin acting at RXFP1 receptors have potential for the development of agents effective for the treatment of cardiac and renal fibrosis, asthma, and scleroderma and for orthodontic remodelling. Agents acting at RXFP2 receptors may be useful for the treatment of cryptorchidism and infertility, whereas antagonists may be used as contraceptives. The brain distribution of RXFP3 receptors suggests that actions at these receptors have the potential for the development of antianxiety and antiobesity drugs.
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Affiliation(s)
- Ross A Bathgate
- Howard Florey Institute, University of Melbourne, Victoria, Australia
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Conrad KP, Novak J. Emerging role of relaxin in renal and cardiovascular function. Am J Physiol Regul Integr Comp Physiol 2004; 287:R250-61. [PMID: 15271674 DOI: 10.1152/ajpregu.00672.2003] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although traditionally associated with reproductive processes, relaxin is emerging as an important player in renal and cardiovascular function. Much of our recently acquired understanding of relaxin in this new context has arisen from studies of maternal renal and cardiovascular adaptations to pregnancy in rats where the hormone is turning out to be an important mediator. First, we highlight the influence of relaxin on renal hemodynamics and glomerular filtration rate, as well as on other peripheral circulations. Second, we discuss the effect of relaxin on both the steady and pulsatile systemic arterial load, as well as on the heart, in particular, coronary blood flow. Third, we consider the impact of the hormone on cultured endothelial and vascular smooth muscle cells. Fourth, we address the interaction of relaxin with renal and cardiac disease, as well as its role in angiogenesis. Finally, in Perspectives, we point out several key research questions in need of investigation that relate to a potential autocrine/paracrine role of relaxin in renal and cardiovascular tissues. Furthermore, on the basis of its potent vasodilatory and matrix-degrading attributes, we speculate about the therapeutic potential of relaxin in renal and cardiovascular diseases.
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Affiliation(s)
- Kirk P Conrad
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, and Magee-Women's Research Institute, Pittsburgh, Pennsylvania 15213, USA.
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Abstract
Relaxin has vital physiological roles in pregnant rats, mice, and pigs. Relaxin promotes growth and softening of the cervix, thus facilitating rapid delivery of live young. Relaxin also promotes development of the mammary apparatus, thus enabling normal lactational performance. The actions of relaxin on the mammary apparatus vary among species. Whereas relaxin is required for development of the mammary nipples in rats and mice, it is essential for prepartum development of glandular parenchyma in pregnant pigs. During pregnancy relaxin also inhibits uterine contractility and promotes the osmoregulatory changes of pregnancy in rats. Recent studies with male and nonpregnant female rodents revealed diverse therapeutic actions of relaxin on nonreproductive tissues that have clinical implications. Relaxin has been reported to reduce fibrosis in the kidney, heart, lung, and liver and to promote wound healing. Also, probably through its vasodilatory actions, relaxin protects the heart from ischemia-induced injury. Finally, relaxin counteracts allergic reactions. Knowledge of the diverse physiological and therapeutic actions of relaxin, coupled with the recent identification of relaxin receptors, opens numerous avenues of investigation that will likely sustain a high level of research interest in relaxin for the foreseeable future.
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Affiliation(s)
- O David Sherwood
- Department of Molecular and Integrative Physiology and College of Medicine, University of Illinois at Urbana-Champaign, 524 Burrill Hall, 407 South Goodwin Avenue, Urbana, IL 61801, USA.
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Kompa AR, Samuel CS, Summers RJ. Inotropic responses to human gene 2 (B29) relaxin in a rat model of myocardial infarction (MI): effect of pertussis toxin. Br J Pharmacol 2002; 137:710-8. [PMID: 12381685 PMCID: PMC1573542 DOI: 10.1038/sj.bjp.0704922] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Relaxin produces powerful inotropic and chronotropic responses in isolated atria. The effect of relaxin has been examined in a rat model of cardiac failure, induced by myocardial infarction (MI). Maximum inotropic responses to isoprenaline (sham 5.4+/-0.3 mN; MI 2.6+/-0.3 mN; P<0.001) and relaxin (sham 5.1+/-0.6 mN; MI 2.8+/-0.5 mN; P=0.013) were reduced in left atria following MI. No change in chronotropic responsiveness was observed in right atria. Pertussis toxin (PTX) treatment restored inotropic responses to isoprenaline (sham 5.5+/-1.3 mN; MI 5.8+/-1.0 mN; P=0.850) but not to relaxin. Instead, PTX reduced inotropic responses to relaxin in sham animals to the same level seen in the MI group (sham 3.2+/-1.7 mN; MI 2.8+/-0.6 mN; P=0.847). In right atria, PTX treatment did not affect the maximum chronotropic response to isoprenaline, but reduced responses to relaxin in both sham and MI animals. R3 relaxin and relaxin receptor (LGR7) mRNA was present in atria and left ventricle (LV) from sham and MI animals. R3 relaxin mRNA expression was increased in atria but not LV from MI animals. LGR7 mRNA expression was reduced in atria and LV from MI animals. PTX treatment in unoperated rats increased chronotropic responses (vehicle 184.3+/-5.3 beats min(-1); PTX 211.3+/-9.5 beats min(-1); P=0.029) and produced a rightward shift in the concentration-response curve to isoprenaline in left atria. PTX reduced inotropic (vehicle 3.3+/-0.7 mN; PTX 0.8+/-0.2 mN; P=0.005) and chronotropic (vehicle 130.2+/-8.1 beats min(-1); PTX 90.6+/-11.1 beats min(-1); P=0.012) responses to relaxin. 6 In left atria, relaxin produced a small increase in cAMP compared to those produced by isoprenaline and forskolin. However, PTX treatment significantly reduced relaxin-, isoprenaline- and forskolin-stimulated cAMP accumulation. Cardiac failure in MI animals caused a reduced inotropic response to both relaxin and (-)-isoprenaline. In non-MI animals, PTX treatment also reduced inotropic responses to relaxin. Differences between responses to (-)-isoprenaline and relaxin can be explained by changes in coupling efficiency occurring at the level of adenylate cyclase.
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Affiliation(s)
- Andrew R Kompa
- Department of Pharmacology, Monash University, Victoria, 3800, Australia
| | - Chrishan S Samuel
- Howard Florey Institute, University of Melbourne, Victoria, 3010, Australia
| | - Roger J Summers
- Department of Pharmacology, Monash University, Victoria, 3800, Australia
- Author for correspondence:
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Nguyen TH, Shire SJ. Stability and characterization of recombinant human relaxin. PHARMACEUTICAL BIOTECHNOLOGY 2002; 9:247-74. [PMID: 8914194 DOI: 10.1007/0-306-47452-2_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- T H Nguyen
- Department of Pharmaceutical Research and Development, Genentech, Inc., South San Francisco, California 94080, USA
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Seeger H, Lüdtke R, Gräser T, Wallwiener D, Mueck AO. Effect of oral contraceptives on the urinary excretion of biochemical markers indicating vasoactive action. J Clin Pharm Ther 2000; 25:221-6. [PMID: 10886466 DOI: 10.1046/j.1365-2710.2000.00283.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE In the present study the effect of two contraceptive pills, i.e. Neorlest, containing ethinylestradiol and norethisterone acetate, and Valette, containing ethinylestradiol and the new progestin dienogest, was investigated on the urinary excretion of vasoactive markers. As markers prostacyclin and its antagonist thromboxane, cGMP, serotonin, and the vasorelaxing mediators relaxin and urodilatin were measured. METHOD 30 women received Neorlest and 33 women Valette in a randomized, open, parallel-group study design. Nocturnal urine was collected before treatment and during cyclic treatment after 6 and 11 weeks. RESULTS For prostacyclin, the ratio of prostacyclin to thromboxane, relaxin and urodilatin significant increases compared to the pretreatment values were observed with Valette within 11 weeks treatment. For the markers cGMP and serotonin both contraceptive pills showed a tendency to an increase of the renal excretion after 11 weeks treatment. No significant differences between the two pills were observed, except in the case of the ratio of prostacyclin to thromboxane, which showed a significant, clear-cut enhancement with Valette. CONCLUSION These results indicate that contraceptive pills may stimulate the production of vasodilative markers, an effect which can be attributed most likely to the oestrogenic component of the pill. The progestogenic component of the pill may elicit an impact on this oestrogen-induced vasodilation, which, however, seems to be minimized in the case of the new compound dienogest, a C-19 progestin with antiandrogenic properties.
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Affiliation(s)
- H Seeger
- Section of Gynecological Endocrinology and Menopause, Department of Obstetrics and Gynecology, University of Tuebingen, Tuebingen, Germany
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Palejwala S, Stein D, Wojtczuk A, Weiss G, Goldsmith LT. Demonstration of a relaxin receptor and relaxin-stimulated tyrosine phosphorylation in human lower uterine segment fibroblasts. Endocrinology 1998; 139:1208-12. [PMID: 9492055 DOI: 10.1210/endo.139.3.5772] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
To elucidate the mechanism of relaxin action, we studied the binding characteristics of human relaxin and its effects on intracellular concentrations of cAMP and tyrosine phosphorylation of cellular proteins in a model system of human cervix, human lower uterine segment fibroblasts. Human relaxin labeled with 125I bound specifically to a single class of high-affinity relaxin binding sites, distinct from insulin receptors, with a mean (+/-SEM) dissociation constant (Kd) of 4.36 +/- 1.7 x 10(-9) M and a mean of 3220 +/- 557 binding sites per cell in human lower uterine segment fibroblasts. Relaxin, in quantities that were shown previously to stimulate intracellular levels of cAMP in other cell types, had no effect on intracellular levels of cAMP in human lower uterine segment fibroblasts even in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methyl-xanthine (IBMX). Incubation of the cells with relaxin caused a significant increase in tyrosine phosphorylation of a protein with an apparent Mr of approximately 220 kDa in these cells. In concert with results of recent studies that demonstrated that the Mr of the relaxin receptor is approximately 220 kDa, our data suggest that the phosphorylated protein is likely to be the relaxin receptor.
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Affiliation(s)
- S Palejwala
- Department of Obstetrics and Gynecology, New Jersey Medical School, Newark 07103, USA
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Tan YY, Wade JD, Tregear GW, Summers RJ. Comparison of relaxin receptors in rat isolated atria and uterus by use of synthetic and native relaxin analogues. Br J Pharmacol 1998; 123:762-70. [PMID: 9517397 PMCID: PMC1565217 DOI: 10.1038/sj.bjp.0701659] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
1. The receptors for relaxin in the rat atria and uterus were investigated and compared by use of a series of synthetic and native relaxin analogues. The assays used were the positive chronotropic and inotropic effects in rat spontaneously beating, isolated right atrium and electrically driven left atrium and the relaxation of K+ precontracted uterine smooth muscle. 2. Relaxin analogues with an intact A- and B-chain were active in producing powerful chronotropic and inotropic effects in the rat isolated atria at nanomolar concentrations. Single-chain analogues and structural homologues of relaxin such as human insulin and sheep insulin-like growth factor I had no agonist action and did not antagonize the effect of the B29 form of human gene 2 relaxin. 3. Shortening the B-chain carboxyl terminal of human gene 1 (B2-29) relaxin to B2-26 reduced the activity of the peptide and removal of another 2 amino acid residues (B2-24) abolished the activity. This suggests that the B-chain length may be important for determination of the activity of relaxin. More detailed studies are needed to determine the effect of progressive amino acid removal on the structure and the bioactivity of relaxin. 4. Porcine prorelaxin was as active as porcine relaxin on a molar basis, suggesting that the presence of the intact C-peptide did not affect the binding of the prorelaxin to the receptor to produce functional responses. 5. Relaxin caused relaxation of uterine longitudinal and circular smooth muscle precontracted with 40 mM K+. The pEC50 values for human gene 2 and porcine relaxins were lower than those in the atrial assay, but rat relaxin had similar pEC50 values in both atrial and uterine assays. Rat relaxin was significantly less potent than either human gene 2 or porcine relaxin in the atrial assay, but in the uterine assay they were equipotent. The results suggest that the relaxin receptor or the signalling pathway in rat atria may differ from that in the uterus.
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Affiliation(s)
- Y Y Tan
- Department of Pharmaceutical Science, Universiti Sains Malaysia, Penang
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Méry PF, Abi-Gerges N, Vandecasteele G, Jurevicius J, Eschenhagen T, Fischmeister R. Muscarinic regulation of the L-type calcium current in isolated cardiac myocytes. Life Sci 1997; 60:1113-20. [PMID: 9121355 DOI: 10.1016/s0024-3205(97)00055-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Muscarinic agonists regulate the L-type calcium current in isolated cardiac myocytes. The second messengers pathways involved in this regulation are discussed briefly, with particular emphasis on the involvement of cAMP and cGMP pathways.
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Affiliation(s)
- P F Méry
- Laboratoire de Cardiologie Cellulaire et Moléculaire, INSERM U446, Université de Paris-Sud, Faculté de Pharmacie, Chatenay-Malabry, France
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Tanaka H, Clark RB, Giles WR. Positive chronotropic responses of rabbit sino-atrial node cells to flash photolysis of caged isoproterenol and cyclic AMP. Proc Biol Sci 1996; 263:241-8. [PMID: 8920247 DOI: 10.1098/rspb.1996.0038] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The kinetics of onset and the intracellular biochemical signalling mechanisms which are responsible for the positive chronotropic effect of sympathetic stimulation in rabbit cardiac pacemaker cells were examined by using flash photolysis of caged isoproterenol (ISO) and cyclic AMP (cAMP). When caged ISO (10 microM) was present in the superfusate, a single ultraviolet flash caused gradual increases in the spontaneous beating frequency and action potential height of S-A node cells. Both these effects developed after an initial latency of approximately 5 s. Photorelease of ISO also increased the L-type Ca2+ current (ICa-L) with a time-course similar to that of the changes in action potential waveform and heart rate. All of these ISO-induced effects were blocked completely by 1 microM propranolol, demonstrating that they were beta-adrenergic responses. Flash photolysis of caged cAMP (50 microM) also resulted in increased firing frequency and ICa-L. However, these responses to cAMP developed with little or no latency. Intracellular dialysis with a selective inhibitor of the cAMP-dependent protein kinase, Rp-cAMPS, completely abolished the increase in ICa-L demonstrating that it is mediated exclusively via cAMP-dependent activation of protein kinase A, as opposed to a direct G-protein mediated mechanism.
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Affiliation(s)
- H Tanaka
- Department of Medicine, University of Calgary, Alberta, Canada
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Han X, Light PE, Giles WR, French RJ. Identification and properties of an ATP-sensitive K+ current in rabbit sino-atrial node pacemaker cells. J Physiol 1996; 490 ( Pt 2):337-50. [PMID: 8821133 PMCID: PMC1158673 DOI: 10.1113/jphysiol.1996.sp021148] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
1. Single myocytes were isolated from rabbit sino-atrial (SA) node by enzymatic dissociation. Spontaneous pacemaker activity, whole-cell and single-channel currents were recorded under conditions known to modulate ATP-sensitive K+ (KATP) channels. 2. The KATP channel openers, cromakalim and pinacidil, slowed or abolished the pacemaker activity, and caused hyperpolarization of the maximum diastolic potential (MDP). Glibenclamide, a KATP channel blocker, reversed these effects. Cromakalim- and pinacidil-activated currents reversed near the potassium equilibrium potential, EK. Glibenclamide had no effect on the L-type calcium current, ICa(L), the hyperpolarization-activated inward current, If, or the delayed rectifier potassium current, IK. 3. Sodium cyanide, which inhibits mitochondrial ATP production, induced a macroscopic current that reversed near EK and was blocked by glibenclamide. 4. In excised, inside-out patches from SA node cells, single KATP channels showed a slope conductance of 52 +/- 8 pS (mean +/- S.D.) when measurements were made at negative voltages in symmetric, 140 mM K+. Channels from ventricular myocytes showed a somewhat larger slope conductance (70 +/- 5 pS). 5. Raising the intracellular ATP concentration caused a concentration-dependent reduction in the open probability of the KATP channels (IC50, 16 microM; Hill coefficient, approximately 1; at both pH 7.4 and 6.8). 6. In excised inside-out patches, cromakalim or pinacidil induced significant increases in KATP channel activity in the presence of 50 microM or 1 mM intracellular ATP. This channel activity was blocked by glibenclamide. 7. Our results suggest that sino-atrial node cells express a distinct isoform of KATP channel which may play an important role in pharmacological and pathophysiological modulation of pacemaker activity.
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Affiliation(s)
- X Han
- Department of Medical Physiology, University of Calgary, Alberta, Canada
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