1
|
Wolf P, Mohr A, Gavins G, Behr V, Mörl K, Seitz O, Beck-Sickinger AG. Orthogonal Peptide-Templated Labeling Elucidates Lateral ET A R/ET B R Proximity and Reveals Altered Downstream Signaling. Chembiochem 2021; 23:e202100340. [PMID: 34699123 PMCID: PMC9298254 DOI: 10.1002/cbic.202100340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 10/03/2021] [Indexed: 12/21/2022]
Abstract
Fine‐tuning of G protein‐coupled receptor (GPCR) signaling is important to maintain cellular homeostasis. Recent studies demonstrated that lateral GPCR interactions in the cell membrane can impact signaling profiles. Here, we report on a one‐step labeling method of multiple membrane‐embedded GPCRs. Based on short peptide tags, complementary probes transfer the cargo (e. g. a fluorescent dye) by an acyl transfer reaction with high spatial and temporal resolution within 5 min. We applied this approach to four receptors of the cardiovascular system: the endothelin receptor A and B (ETAR and ETBR), angiotensin II receptor type 1, and apelin. Wild type‐like G protein activation after N‐terminal modification was demonstrated for all receptor species. Using FRET‐competent dyes, a constitutive proximity between hetero‐receptors was limited to ETAR/ETBR. Further, we demonstrate, that ETAR expression regulates the signaling of co‐expressed ETBR. Our orthogonal peptide‐templated labeling of different GPCRs provides novel insight into the regulation of GPCR signaling.
Collapse
Affiliation(s)
- Philipp Wolf
- Faculty of Life Sciences, Institute of Biochemistry, Leipzig University, Brüderstrasse 34, 04103, Leipzig, Germany
| | - Alexander Mohr
- Faculty of Life Sciences, Institute of Biochemistry, Leipzig University, Brüderstrasse 34, 04103, Leipzig, Germany
| | - Georgina Gavins
- Faculty of Mathematics and Natural Sciences, Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany
| | - Victoria Behr
- Faculty of Life Sciences, Institute of Biochemistry, Leipzig University, Brüderstrasse 34, 04103, Leipzig, Germany
| | - Karin Mörl
- Faculty of Life Sciences, Institute of Biochemistry, Leipzig University, Brüderstrasse 34, 04103, Leipzig, Germany
| | - Oliver Seitz
- Faculty of Mathematics and Natural Sciences, Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany
| | - Annette G Beck-Sickinger
- Faculty of Life Sciences, Institute of Biochemistry, Leipzig University, Brüderstrasse 34, 04103, Leipzig, Germany
| |
Collapse
|
2
|
Koyama Y. Endothelin ET B Receptor-Mediated Astrocytic Activation: Pathological Roles in Brain Disorders. Int J Mol Sci 2021; 22:ijms22094333. [PMID: 33919338 PMCID: PMC8122402 DOI: 10.3390/ijms22094333] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/16/2021] [Accepted: 04/19/2021] [Indexed: 12/11/2022] Open
Abstract
In brain disorders, reactive astrocytes, which are characterized by hypertrophy of the cell body and proliferative properties, are commonly observed. As reactive astrocytes are involved in the pathogenesis of several brain disorders, the control of astrocytic function has been proposed as a therapeutic strategy, and target molecules to effectively control astrocytic functions have been investigated. The production of brain endothelin-1 (ET-1), which increases in brain disorders, is involved in the pathophysiological response of the nervous system. Endothelin B (ETB) receptors are highly expressed in reactive astrocytes and are upregulated by brain injury. Activation of astrocyte ETB receptors promotes the induction of reactive astrocytes. In addition, the production of various astrocyte-derived factors, including neurotrophic factors and vascular permeability regulators, is regulated by ETB receptors. In animal models of Alzheimer’s disease, brain ischemia, neuropathic pain, and traumatic brain injury, ETB-receptor-mediated regulation of astrocytic activation has been reported to improve brain disorders. Therefore, the astrocytic ETB receptor is expected to be a promising drug target to improve several brain disorders. This article reviews the roles of ETB receptors in astrocytic activation and discusses its possible applications in the treatment of brain disorders.
Collapse
Affiliation(s)
- Yutaka Koyama
- Laboratory of Pharmacology, Kobe Pharmaceutical University, 4-19-1 Motoyama-Kita Higashinada, Kobe 668-8558, Japan
| |
Collapse
|
3
|
Zrein A, Bagher AM, Young AP, Denovan-Wright EM, Kelly MEM. Endothelin receptor heteromerization inhibits β-arrestin function in HEK293 cells. Can J Physiol Pharmacol 2020; 98:531-540. [PMID: 32744876 DOI: 10.1139/cjpp-2019-0620] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The endothelin receptor A (ETA) and endothelin receptor B (ETB) are G protein-coupled receptors that are co-expressed in vascular smooth muscle cells. Endothelin-1 (ET-1) activates endothelin receptors to cause microvascular vasoconstriction. Previous studies have shown that heteromerization between ETA and ETB prolongs Ca2+ transients, leading to prolongation of Gαq-dependent signaling and sustained vasoconstriction. We hypothesized that these effects are in part mediated by the resistance of ETA/ETB heteromers to β-arrestin recruitment and subsequent desensitization. Using bioluminescence resonance energy transfer 2 (BRET2), we found that ETB has a relatively equal affinity to form either homomers or heteromers with ETA when co-expressed in the human embryonic kidney 293 (HEK293) cells. When co-expressed, activation of ETA and ETB by ET-1 caused a heteromer-specific reduction and delay in β-arrestin-2 recruitment with a corresponding reduction and delay in ET-1-induced ETA/ETB co-internalization. Furthermore, the co-expression of ETA and ETB inhibited ET-1-induced β-arrestin-1-dependent extracellular signal-regulated kinase (ERK) phosphorylation while prolonging ET-1-induced Gαq-dependent ERK phosphorylation. ETA/ETB heteromerization mediates the long-lasting vasoconstrictor response to ET-1 by the prolongation of Gαq-dependent signaling and inhibition of β-arrestin function.
Collapse
Affiliation(s)
- Adel Zrein
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Amina M Bagher
- Department of Pharmacology and Toxicology, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Alexander P Young
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | | | - Melanie E M Kelly
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H 4R2, Canada.,Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, NS B3H 4R2, Canada
| |
Collapse
|
4
|
Target-Mediated Drug Disposition Pharmacokinetic–Pharmacodynamic Model of Bosentan and Endothelin-1. Clin Pharmacokinet 2017; 56:1499-1511. [DOI: 10.1007/s40262-017-0534-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|
5
|
Functional ET(A)-ET(B) Receptor Cross-talk in Basilar Artery In Situ From ET(B) Receptor Deficient Rats. J Cardiovasc Pharmacol 2016; 67:212-7. [PMID: 26528589 DOI: 10.1097/fjc.0000000000000335] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The role of endothelin (ET)(A)-ET(B) receptor cross-talk in limiting the ET(A) receptor antagonist inhibition of ET-1 constriction is revealed by the partial or complete dependency of the ET(A) receptor antagonist inhibition on functional removal of the ET(B) receptor. Although functional removal of the ET(B) receptor is generally accomplished with ET(B) receptor antagonist, a novel approach using rats containing a naturally occurring deletion mutation in the ET(B) receptor [rescued "spotting lethal" (sl) rats; ET(B)(sl/sl)] demonstrated increased ET(A) receptor antagonist inhibition of ET-1 constriction in vena cava. We investigated whether this deletion mutation was also sufficient to remove the ET(B) receptor dependency of the ET(A) receptor antagonist inhibition of ET-1 constriction in the basilar artery. Consistent with previous reports, ET-1 plasma levels were elevated in ET(B)(sl/sl) as compared with ET(B)(+/+) rats. ET(B) receptor antagonist failed to relax the ET-1 constricted basilar artery from ET(B)(+/+) and ET(B)(sl/sl) rats. Relaxation to combined ET(A) and ET(B) receptor antagonist was greater than relaxation to ET(A) receptor antagonist in the basilar artery from ET(B)(+/+) and, unexpectedly, ET(B)(sl/sl) rats. These findings confirm the presence of ET(A)-ET(B) receptor cross-talk in the basilar artery. We speculate that mutant ET(B) receptor expression produced by alternative splicing may be sufficient to allow cross-talk.
Collapse
|
6
|
Endothelin-1: Biosynthesis, Signaling and Vasoreactivity. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 77:143-75. [PMID: 27451097 DOI: 10.1016/bs.apha.2016.05.002] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Endothelin-1 (ET-1) is an extremely potent vasoconstrictor peptide originally isolated from endothelial cells. Its synthesis, mainly regulated at the gene transcription level, involves processing of a precursor by a furin-type proprotein convertase to an inactive intermediate, big ET-1. The latter peptide can then be cleaved directly by an endothelin-converting enzyme (ECE) into ET-1 or reach the active metabolite through a two-step process involving chymase hydrolyzing big ET-1 to ET-1 (1-31), itself needing conversion to ET-1 by neprilysin (NEP) to exert physiological activity. ET-1 signals through two G protein-coupled receptors, endothelin receptor A (ETA) and endothelin receptor B (ETB). Both receptors induce an increase in intracellular Ca(2+), mainly from the extracellular space through voltage-independent mechanisms, the receptor-operated channels and store-operated channels. ET-1 also induces signaling through epidermal growth factor receptor transactivation, oxidative stress induction, rho-kinase, and the activation (ETA) or inhibition (ETB) of the adenylate cyclase/cyclic adenosine monophosphate pathway. Arterial vasoconstriction is mediated mainly by the ETA receptor. ET-1, via endothelium-located ETB, relaxes arteries or constricts vessels following activation of the same receptor type on the smooth muscle, where it can interact with ETA. In addition, ETB-dependent vasoconstriction seems more prominent in the venous vasculature. A better understanding of how ET-1 is synthesized and how ETA and ETB receptors interact could help design better pharmacological agents in the treatment of cardiovascular diseases where targeting the ET-1 system is indicated.
Collapse
|
7
|
Davenport AP, Hyndman KA, Dhaun N, Southan C, Kohan DE, Pollock JS, Pollock DM, Webb DJ, Maguire JJ. Endothelin. Pharmacol Rev 2016; 68:357-418. [PMID: 26956245 PMCID: PMC4815360 DOI: 10.1124/pr.115.011833] [Citation(s) in RCA: 489] [Impact Index Per Article: 61.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The endothelins comprise three structurally similar 21-amino acid peptides. Endothelin-1 and -2 activate two G-protein coupled receptors, ETA and ETB, with equal affinity, whereas endothelin-3 has a lower affinity for the ETA subtype. Genes encoding the peptides are present only among vertebrates. The ligand-receptor signaling pathway is a vertebrate innovation and may reflect the evolution of endothelin-1 as the most potent vasoconstrictor in the human cardiovascular system with remarkably long lasting action. Highly selective peptide ETA and ETB antagonists and ETB agonists together with radiolabeled analogs have accurately delineated endothelin pharmacology in humans and animal models, although surprisingly no ETA agonist has been discovered. ET antagonists (bosentan, ambrisentan) have revolutionized the treatment of pulmonary arterial hypertension, with the next generation of antagonists exhibiting improved efficacy (macitentan). Clinical trials continue to explore new applications, particularly in renal failure and for reducing proteinuria in diabetic nephropathy. Translational studies suggest a potential benefit of ETB agonists in chemotherapy and neuroprotection. However, demonstrating clinical efficacy of combined inhibitors of the endothelin converting enzyme and neutral endopeptidase has proved elusive. Over 28 genetic modifications have been made to the ET system in mice through global or cell-specific knockouts, knock ins, or alterations in gene expression of endothelin ligands or their target receptors. These studies have identified key roles for the endothelin isoforms and new therapeutic targets in development, fluid-electrolyte homeostasis, and cardiovascular and neuronal function. For the future, novel pharmacological strategies are emerging via small molecule epigenetic modulators, biologicals such as ETB monoclonal antibodies and the potential of signaling pathway biased agonists and antagonists.
Collapse
Affiliation(s)
- Anthony P Davenport
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - Kelly A Hyndman
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - Neeraj Dhaun
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - Christopher Southan
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - Donald E Kohan
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - Jennifer S Pollock
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - David M Pollock
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - David J Webb
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| | - Janet J Maguire
- Experimental Medicine and Immunotherapeutics, University of Cambridge, Cambridge, United Kingdom (A.P.D., J.J.M.); IUPHAR/BPS Guide to PHARMACOLOGY, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, United Kingdom (C.S.); Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah (D.E.K.); Cardio-Renal Physiology & Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama (K.A.H., J.S.P., D.M.P.); and Department of Renal Medicine, Royal Infirmary of Edinburgh (N.D.) and University/British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute (D.J.W.N.D.), Edinburgh, Scotland, United Kingdom
| |
Collapse
|
8
|
Affiliation(s)
- Donald E Kohan
- Division of Nephrology University of Utah Health Sciences Center Salt Lake City, UT
| |
Collapse
|
9
|
Tran QK, VerMeer M, Burgard MA, Hassan AB, Giles J. Hetero-oligomeric Complex between the G Protein-coupled Estrogen Receptor 1 and the Plasma Membrane Ca2+-ATPase 4b. J Biol Chem 2015; 290:13293-307. [PMID: 25847233 DOI: 10.1074/jbc.m114.628743] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Indexed: 11/06/2022] Open
Abstract
The new G protein-coupled estrogen receptor 1 (GPER/GPR30) plays important roles in many organ systems. The plasma membrane Ca(2+)-ATPase (PMCA) is essential for removal of cytoplasmic Ca(2+) and for shaping the time courses of Ca(2+)-dependent activities. Here, we show that PMCA and GPER/GPR30 physically interact and functionally influence each other. In primary endothelial cells, GPER/GPR30 agonist G-1 decreases PMCA-mediated Ca(2+) extrusion by promoting PMCA tyrosine phosphorylation. GPER/GPR30 overexpression decreases PMCA activity, and G-1 further potentiates this effect. GPER/GPR30 knockdown increases PMCA activity, whereas PMCA knockdown substantially reduces GPER/GPR30-mediated phosphorylation of the extracellular signal-related kinase (ERK1/2). GPER/GPR30 co-immunoprecipitates with PMCA with or without treatment with 17β-estradiol, thapsigargin, or G-1. Heterologously expressed GPER/GPR30 in HEK 293 cells co-localizes with PMCA4b, the main endothelial PMCA isoform. Endothelial cells robustly express the PDZ post-synaptic density protein (PSD)-95, whose knockdown reduces the association between GPER/GPR30 and PMCA. Additionally, the association between PMCA4b and GPER/GPR30 is substantially reduced by truncation of either or both of their C-terminal PDZ-binding motifs. Functionally, inhibition of PMCA activity is significantly reduced by truncation of GPER/GPR30's C-terminal PDZ-binding motif. These data strongly indicate that GPER/GPR30 and PMCA4b form a hetero-oligomeric complex in part via the anchoring action of PSD-95, in which they constitutively affect each other's function. Activation of GPER/GPR30 further inhibits PMCA activity through tyrosine phosphorylation of the pump. These interactions represent cross-talk between Ca(2+) signaling and GPER/GPR30-mediated activities.
Collapse
Affiliation(s)
- Quang-Kim Tran
- From the Department of Physiology and Pharmacology, College of Osteopathic Medicine, Des Moines University, Des Moines, Iowa 50312
| | - Mark VerMeer
- From the Department of Physiology and Pharmacology, College of Osteopathic Medicine, Des Moines University, Des Moines, Iowa 50312
| | - Michelle A Burgard
- From the Department of Physiology and Pharmacology, College of Osteopathic Medicine, Des Moines University, Des Moines, Iowa 50312
| | - Ali B Hassan
- From the Department of Physiology and Pharmacology, College of Osteopathic Medicine, Des Moines University, Des Moines, Iowa 50312
| | - Jennifer Giles
- From the Department of Physiology and Pharmacology, College of Osteopathic Medicine, Des Moines University, Des Moines, Iowa 50312
| |
Collapse
|
10
|
Barr TP, Kornberg D, Montmayeur JP, Long M, Reichheld S, Strichartz GR. Validation of endothelin B receptor antibodies reveals two distinct receptor-related bands on Western blot. Anal Biochem 2015; 468:28-33. [PMID: 25232999 DOI: 10.1016/j.ab.2014.09.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 08/29/2014] [Accepted: 09/08/2014] [Indexed: 10/24/2022]
Abstract
Antibodies are important tools for the study of protein expression but are often used without full validation. In this study, we used Western blots to characterize antibodies targeted to the N or C terminal (NT or CT, respectively) and the second or third intracellular loop (IL2 or IL3, respectively) of the endothelin B receptor (ETB). The IL2-targeted antibody accurately detected endogenous ETB expression in rat brain and cultured rat astrocytes by labeling a 50-kDa band, the expected weight of full-length ETB. However, this antibody failed to detect transfected ETB in HEK293 cultures. In contrast, the NT-targeted antibody accurately detected endogenous ETB in rat astrocyte cultures and transfected ETB in HEK293 cultures by labeling a 37-kDa band but failed to detect endogenous ETB in rat brain. Bands detected by the CT- or IL3-targeted antibody were found to be unrelated to ETB. Our findings show that functional ETB can be detected at 50 or 37kDa on Western blot, with drastic differences in antibody affinity for these bands. The 37-kDa band likely reflects ETB processing, which appears to be dependent on cell type and/or culture condition.
Collapse
Affiliation(s)
- Travis P Barr
- Pain Research Center, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham & Women's Hospital, Boston, MA 02115, USA
| | - Daniel Kornberg
- Pain Research Center, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham & Women's Hospital, Boston, MA 02115, USA
| | - Jean-Pierre Montmayeur
- Pain Research Center, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham & Women's Hospital, Boston, MA 02115, USA
| | - Melinda Long
- Pain Research Center, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham & Women's Hospital, Boston, MA 02115, USA
| | - Stephen Reichheld
- Pain Research Center, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham & Women's Hospital, Boston, MA 02115, USA
| | - Gary R Strichartz
- Pain Research Center, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham & Women's Hospital, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
| |
Collapse
|
11
|
Ortiz-Capisano MC. Endothelin inhibits renin release from juxtaglomerular cells via endothelin receptors A and B via a transient receptor potential canonical-mediated pathway. Physiol Rep 2014; 2:2/12/e12240. [PMID: 25524278 PMCID: PMC4332218 DOI: 10.14814/phy2.12240] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Renin is the rate-limiting step in the production of angiotensin II: a critical element in the regulation of blood pressure and in the pathogenesis of hypertension. Renin release from the juxtaglomerular (JG) cell is stimulated by the second messenger cAMP and inhibited by increases in calcium (Ca). Endothelins (ETs) inhibit renin release in a Ca-dependent manner. JG cells contain multiple isoforms of canonical transient receptor potential (TRPC) Ca-permeable channels. The proposed hypothesis is that endothelin inhibits renin release by activating TRPC store-operated Ca channels. RT-PCR and immunofluorescence revealed expression of both ETA and ETB receptors in mouse JG cells. Incubation of primary cultures of JG cells with ET-1 (10 nmol/L) decreased renin release by 28%. Addition of either an ETA or an ETB receptor blocker completely prevented the ET inhibition of renin release. Incubation with the TRPC blocker (SKF 96365, 50 μmol/L) completely reversed the Ca-mediated inhibition of renin release by ETs. These results suggest that endothelin inhibits renin release from JG cells via both ETA and ETB receptors, which leads to the activation of TRPC store-operated Ca channels.
Collapse
Affiliation(s)
- M Cecilia Ortiz-Capisano
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan
| |
Collapse
|
12
|
Maffei R, Bulgarelli J, Fiorcari S, Martinelli S, Castelli I, Valenti V, Rossi D, Bonacorsi G, Zucchini P, Potenza L, Vallisa D, Gattei V, Poeta GD, Forconi F, Gaidano G, Narni F, Luppi M, Marasca R. Endothelin-1 promotes survival and chemoresistance in chronic lymphocytic leukemia B cells through ETA receptor. PLoS One 2014; 9:e98818. [PMID: 24901342 PMCID: PMC4046988 DOI: 10.1371/journal.pone.0098818] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 05/07/2014] [Indexed: 11/26/2022] Open
Abstract
The endothelin axis, comprising endothelins (ET-1, ET-2 and ET-3) and their receptors (ET(A)R and ETBR), has emerged as relevant player in tumor growth and metastasis. Here, we investigated the involvement of ET-1/ET(A)R axis in chronic lymphocytic leukemia (CLL). CLL cells expressed higher levels of ET-1 and ETA receptor as compared to normal B cells. ET-1 peptide stimulated phosphoinositide-3-kinase and mitogen-activated protein kinase signaling pathways, improved survival and promoted proliferation of leukemic cells throughout ET(A)R triggering. Moreover, the blockade of ET(A)R by the selective antagonist BQ-123 inhibited the survival advantage acquired by CLL cells in contact with endothelial layers. We also found that blocking ET(A)R via BQ-123 interferes with ERK phosphorylation and CLL pro-survival effect mediated by B-cell receptor (BCR) activation. The pro-apoptotic effect of phosphoinositide-3-kinase δ inhibitor idelalisib and mitogen-activated protein kinase inhibitor PD98059 was decreased by the addition of ET-1 peptide. Then, ET-1 also reduced the cytotoxic effect of fludarabine on CLL cells cultured alone or co-cultured on endothelial layers. ET(A)R blockade by BQ-123 inhibited the ET-1-mediated protection against drug-induced apoptosis. Lastly, higher plasma levels of big ET-1 were detected in patients (n = 151) with unfavourable prognostic factors and shorter time to first treatment. In conclusion, our data describe for the first time a role of ET-1/ET(A)R signaling in CLL pathobiology. ET-1 mediates survival, drug-resistance, and growth signals in CLL cells that can be blocked by ET(A)R inhibition.
Collapse
MESH Headings
- Antineoplastic Combined Chemotherapy Protocols/therapeutic use
- Cell Proliferation
- Cell Survival/drug effects
- Cell Survival/genetics
- Drug Resistance, Neoplasm/genetics
- Endothelin A Receptor Antagonists/pharmacology
- Endothelin-1/blood
- Endothelin-1/genetics
- Endothelin-1/metabolism
- Gene Expression
- Humans
- Leukemia, Lymphocytic, Chronic, B-Cell/diagnosis
- Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy
- Leukemia, Lymphocytic, Chronic, B-Cell/genetics
- Leukemia, Lymphocytic, Chronic, B-Cell/metabolism
- Leukemia, Lymphocytic, Chronic, B-Cell/mortality
- Prognosis
- Receptor, Endothelin A/genetics
- Receptor, Endothelin A/metabolism
- Receptors, Antigen, B-Cell/metabolism
- Signal Transduction/drug effects
- Treatment Outcome
Collapse
Affiliation(s)
- Rossana Maffei
- Hematology Division, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Jenny Bulgarelli
- Hematology Division, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Stefania Fiorcari
- Hematology Division, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Silvia Martinelli
- Hematology Division, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Ilaria Castelli
- Hematology Division, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | | | - Davide Rossi
- Hematology Division, Department of Clinical and Experimental Medicine, Amedeo Avogadro University of Eastern Piedmont, Novara, Italy
| | - Goretta Bonacorsi
- Hematology Division, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Patrizia Zucchini
- Hematology Division, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Leonardo Potenza
- Hematology Division, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | | | - Valter Gattei
- Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano (PN), Italy
| | - Giovanni Del Poeta
- Hematology Division, S.Eugenio Hospital and University of Tor Vergata, Rome, Italy
| | - Francesco Forconi
- Cancer Sciences Unit, CRUK Clinical Centre, University of Southampton, Southampton, United Kingdom
- Hematology Division, Department of Clinical Medicine and Immunological Sciences, University of Siena, Siena, Italy
| | - Gianluca Gaidano
- Hematology Division, Department of Clinical and Experimental Medicine, Amedeo Avogadro University of Eastern Piedmont, Novara, Italy
| | - Franco Narni
- Hematology Division, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Mario Luppi
- Hematology Division, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Roberto Marasca
- Hematology Division, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| |
Collapse
|
13
|
Lenoir O, Milon M, Virsolvy A, Hénique C, Schmitt A, Massé JM, Kotelevtsev Y, Yanagisawa M, Webb DJ, Richard S, Tharaux PL. Direct action of endothelin-1 on podocytes promotes diabetic glomerulosclerosis. J Am Soc Nephrol 2014; 25:1050-62. [PMID: 24722437 DOI: 10.1681/asn.2013020195] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The endothelin system has emerged as a novel target for the treatment of diabetic nephropathy. Endothelin-1 promotes mesangial cell proliferation and sclerosis. However, no direct pathogenic effect of endothelin-1 on podocytes has been shown in vivo and endothelin-1 signaling in podocytes has not been investigated. This study investigated endothelin effects in podocytes during experimental diabetic nephropathy. Stimulation of primary mouse podocytes with endothelin-1 elicited rapid calcium transients mediated by endothelin type A receptors (ETARs) and endothelin type B receptors (ETBRs). We then generated mice with a podocyte-specific double deletion of ETAR and ETBR (NPHS2-Cre×Ednra(lox/lox)×Ednrb(lox/lox) [Pod-ETRKO]). In vitro, treatment with endothelin-1 increased total β-catenin and phospho-NF-κB expression in wild-type glomeruli, but this effect was attenuated in Pod-ETRKO glomeruli. After streptozotocin injection to induce diabetes, wild-type mice developed mild diabetic nephropathy with microalbuminuria, mesangial matrix expansion, glomerular basement membrane thickening, and podocyte loss, whereas Pod-ETRKO mice presented less albuminuria and were completely protected from glomerulosclerosis and podocyte loss, even when uninephrectomized. Moreover, glomeruli from normal and diabetic Pod-ETRKO mice expressed substantially less total β-catenin and phospho-NF-κB compared with glomeruli from counterpart wild-type mice. This evidence suggests that endothelin-1 drives development of glomerulosclerosis and podocyte loss through direct activation of endothelin receptors and NF-κB and β-catenin pathways in podocytes. Notably, both the expression and function of the ETBR subtype were found to be important. Furthermore, these results indicate that activation of the endothelin-1 pathways selectively in podocytes mediates pathophysiologic crosstalk that influences mesangial architecture and sclerosis.
Collapse
Affiliation(s)
- Olivia Lenoir
- Paris Cardiovascular Research Centre, Institut National de la Santé et de la Recherche Médicale, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Marine Milon
- Paris Cardiovascular Research Centre, Institut National de la Santé et de la Recherche Médicale, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Anne Virsolvy
- Physiologie et Médecine expérimentale du Cœur et des Muscles, Institut National de la Santé et de la Recherche Médicale U1046, Université Montpellier 1, Université Montpellier 2, Montpellier, France
| | - Carole Hénique
- Paris Cardiovascular Research Centre, Institut National de la Santé et de la Recherche Médicale, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Alain Schmitt
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Transmission Electron Microscopy Platform, Institut National de la Santé et de la Recherche Médicale U1016, Cochin Institut, Paris, France; Centre National de la Recherche Scientifique UMR81044, Paris, France
| | - Jean-Marc Massé
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Transmission Electron Microscopy Platform, Institut National de la Santé et de la Recherche Médicale U1016, Cochin Institut, Paris, France; Centre National de la Recherche Scientifique UMR81044, Paris, France
| | - Yuri Kotelevtsev
- The Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom; Pushchino State Institute for Natural Sciences, Pushchino, Moscow Region, Russian Federation
| | | | - David J Webb
- The Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Sylvain Richard
- Physiologie et Médecine expérimentale du Cœur et des Muscles, Institut National de la Santé et de la Recherche Médicale U1046, Université Montpellier 1, Université Montpellier 2, Montpellier, France
| | - Pierre-Louis Tharaux
- Paris Cardiovascular Research Centre, Institut National de la Santé et de la Recherche Médicale, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Nephrology Service, Georges Pompidou European Hospital, Assistance Publique Hopitaux de Paris, Paris, France
| |
Collapse
|
14
|
Endothelin receptor polymorphisms in the cardiovascular system: potential implications for therapy and screening. Heart Fail Rev 2014; 19:743-58. [DOI: 10.1007/s10741-014-9426-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
15
|
Rasmussen MNP, Hornbak M, Larsen SS, Sheykhzade M, Edvinsson L. Permanent distal occlusion of middle cerebral artery in rat causes local increased ETB, 5-HT₁B and AT₁ receptor-mediated contractility downstream of occlusion. J Vasc Res 2013; 50:396-409. [PMID: 23988741 DOI: 10.1159/000354242] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 07/05/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS In response to experimental stroke, a characteristic functional and expressional upregulation of contractile G-protein-coupled receptors has been uncovered in the affected cerebral vasculature; however, the mechanism initiating this phenomenon remains unknown. METHODS Using a model of permanent distal occlusion of rat middle cerebral arteries, we investigated whether there was a regional difference in receptor-mediated contractility of segments located upstream and downstream of the occlusion site. The contractile response to endothelin, angiotensin and 5-hydroxytryptamine receptor stimulation was studied by sensitive wire myograph. RESULTS Only downstream segments exhibited an augmented contractile response to stimulation with each of the three ligands, with the response towards sarafotoxin 6c being especially augmented compared to sham, upstream and contralateral controls. This functional increase did not seem to relate to ischemic tissue damage, inflammatory cell infiltration or the element of reperfusion. Interestingly, immunohistochemistry did not show any difference in the level of immunoreactivity towards endothelin B (ETB) receptors between groups. CONCLUSION Single artery occlusion without significant visible infarct resulted in locally increased ETB, angiotensin type 1 and 5-hydroxytryptamine 1B receptor-mediated contractile responses only in segments located downstream of the occlusion site. This suggests lack of wall stress as an initiating trigger leading to regulation of contractile response after cerebral stroke.
Collapse
Affiliation(s)
- Marianne N P Rasmussen
- Department of Clinical Experimental Research, Glostrup Research Institute, Glostrup University Hospital, Glostrup, Denmark
| | | | | | | | | |
Collapse
|
16
|
Kohan DE. Role of collecting duct endothelin in control of renal function and blood pressure. Am J Physiol Regul Integr Comp Physiol 2013; 305:R659-68. [PMID: 23986358 DOI: 10.1152/ajpregu.00345.2013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Over 26,000 manuscripts have been published dealing with endothelins since their discovery 25 years ago. These peptides, and particularly endothelin-1 (ET-1), are expressed by, bind to, and act on virtually every cell type in the body, influencing multiple biological functions. Among these actions, the effects of ET-1 on arterial pressure and volume homeostasis have been most extensively studied. While ET-1 modulates arterial pressure through regulation of multiple organ systems, the peptide's actions in the kidney in general, and the collecting duct in particular, are of unique importance. The collecting duct produces large amounts of ET-1 that bind in an autocrine manner to endothelin A and B receptors, causing inhibition of Na(+) and water reabsorption; absence of collecting duct ET-1 or its receptors is associated with marked salt-sensitive hypertension. Collecting duct ET-1 production is stimulated by Na(+) and water loading through local mechanisms that include sensing of salt and other solute delivery as well as shear stress. Thus the collecting duct ET-1 system exists, at least in part, to detect alterations in, and maintain homeostasis for, extracellular fluid volume. Derangements in collecting duct ET-1 production may contribute to the pathogenesis of genetic hypertension. Blockade of endothelin receptors causes fluid retention due, in large part, to inhibition of the action of ET-1 in the collecting duct; this side effect has substantially limited the clinical utility of this class of drugs. Herein, the biology of the collecting duct ET-1 system is reviewed, with particular emphasis on key issues and questions that need addressing.
Collapse
Affiliation(s)
- Donald E Kohan
- Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah
| |
Collapse
|
17
|
Drawnel FM, Archer CR, Roderick HL. The role of the paracrine/autocrine mediator endothelin-1 in regulation of cardiac contractility and growth. Br J Pharmacol 2013; 168:296-317. [PMID: 22946456 DOI: 10.1111/j.1476-5381.2012.02195.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Revised: 08/23/2012] [Accepted: 08/28/2012] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Endothelin-1 (ET-1) is a critical autocrine and paracrine regulator of cardiac physiology and pathology. Produced locally within the myocardium in response to diverse mechanical and neurohormonal stimuli, ET-1 acutely modulates cardiac contractility. During pathological cardiovascular conditions such as ischaemia, left ventricular hypertrophy and heart failure, myocyte expression and activity of the entire ET-1 system is enhanced, allowing the peptide to both initiate and maintain maladaptive cellular responses. Both the acute and chronic effects of ET-1 are dependent on the activation of intracellular signalling pathways, regulated by the inositol-trisphosphate and diacylglycerol produced upon activation of the ET(A) receptor. Subsequent stimulation of protein kinases C and D, calmodulin-dependent kinase II, calcineurin and MAPKs modifies the systolic calcium transient, myofibril function and the activity of transcription factors that coordinate cellular remodelling. The precise nature of the cellular response to ET-1 is governed by the timing, localization and context of such signals, allowing the peptide to regulate both cardiomyocyte physiology and instigate disease. LINKED ARTICLES This article is part of a themed section on Endothelin. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.168.issue-1.
Collapse
Affiliation(s)
- Faye M Drawnel
- Babraham Research Campus, Babraham Institute, Cambridge, UK
| | | | | |
Collapse
|
18
|
Stuart D, Chapman M, Rees S, Woodward S, Kohan DE. Myocardial, smooth muscle, nephron, and collecting duct gene targeting reveals the organ sites of endothelin A receptor antagonist fluid retention. J Pharmacol Exp Ther 2013; 346:182-9. [PMID: 23709116 DOI: 10.1124/jpet.113.205286] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Endothelin-1 binding to endothelin A receptors (ETA) elicits profibrogenic, proinflammatory, and proliferative effects that can promote a wide variety of diseases. Although ETA antagonists are approved for the treatment of pulmonary hypertension, their clinical utility in several other diseases has been limited by fluid retention. ETA blocker-induced fluid retention could be due to inhibition of ETA activation in the heart, vasculature, and/or kidney; consequently, the current study was designed to define which of these sites are involved. Mice were generated with absence of ETA specifically in cardiomyocytes (heart), smooth muscle, the nephron, the collecting duct, or no deletion (control). Administration of the ETA antagonist ambrisentan or atrasentan for 2 weeks caused fluid retention in control mice on a high-salt diet as assessed by increases in body weight, total body water, and extracellular fluid volume (using impedance plethysmography), as well as decreases in hematocrit (hemodilution). Mice with heart ETA knockout retained fluid in a similar manner as controls when treated with ambrisentan or atrasentan. Mice with smooth muscle ETA knockout had substantially reduced fluid retention in response to either ETA antagonist. Mice with nephron or collecting duct ETA disruption were completely prevented from ETA blocker-induced fluid retention. Taken together, these findings suggest that ETA antagonist-induced fluid retention is due to a direct effect of this class of drug on the collecting duct, is partially related to the vascular action of the drugs, and is not due to alterations in cardiac function.
Collapse
Affiliation(s)
- Deborah Stuart
- Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, UT 84132, USA
| | | | | | | | | |
Collapse
|
19
|
Stuart D, Rees S, Woodward SK, Koesters R, Strait KA, Kohan DE. Disruption of the endothelin A receptor in the nephron causes mild fluid volume expansion. BMC Nephrol 2012; 13:166. [PMID: 23217151 PMCID: PMC3537641 DOI: 10.1186/1471-2369-13-166] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 11/27/2012] [Indexed: 11/10/2022] Open
Abstract
Background Endothelin, via endothelin A receptors (ETA), exerts multiple pathologic effects that contribute to disease pathogenesis throughout the body. ETA antagonists ameliorate many experimental diseases and have been extensively utilized in clinical trials. The utility of ETA blockers has been greatly limited, however, by fluid retention, sometimes leading to heart failure or death. To begin to examine this issue, the effect of genetic disruption of ETA in the nephron on blood pressure and salt handling was determined. Methods Mice were generated with doxycycline-inducible nephron-specific ETA deletion using Pax8-rtTA and LC-1 transgenes on the background of homozygous loxP-flanked ETA alleles. Arterial pressure, Na metabolism and measures of body fluid volume status (hematocrit and impedance plethysmography) were assessed. Results Absence of nephron ETA did not alter arterial pressure whether mice were ingesting a normal or high Na diet. Nephron ETA disruption did not detectably affect 24 hr Na excretion or urine volume regardless of Na intake. However, mice with nephron ETA knockout that were fed a high Na diet had mild fluid retention as evidenced by an increase in body weight and a fall in hematocrit. Conclusions Genetic deletion of nephron ETA causes very modest fluid retention that does not alter arterial pressure. Nephron ETA, under normal conditions, likely do not play a major role in regulation of Na excretion or systemic hemodynamics.
Collapse
Affiliation(s)
- Deborah Stuart
- Division of Nephrology, University of Utah Health Sciences Center, 1900 East 30 North, Salt Lake City, UT 84132, USA
| | | | | | | | | | | |
Collapse
|
20
|
Why two endothelins and two receptors for ovulation and luteal regulation? Life Sci 2012; 91:501-6. [DOI: 10.1016/j.lfs.2012.05.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2012] [Revised: 05/11/2012] [Accepted: 05/19/2012] [Indexed: 01/12/2023]
|
21
|
Sallum CO, Wilson JL, Rupasinghe C, Berg E, Yu J, Green DS, Taylor L, Mierke D, Polgar P. Enhancing and limiting endothelin-1 signaling with a cell-penetrating peptide mimicking the third intracellular loop of the ETB receptor. Chem Biol Drug Des 2012; 80:374-81. [PMID: 22553998 DOI: 10.1111/j.1747-0285.2012.01405.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
TAT (a 13-mer derived from the HIV-1 Tat protein)-linked cell-permeable peptides deliver plasma membrane impermeable cargos into the cell. We investigated the effect of a TAT-linked intracellular third loop of the endothelin-1 type B receptor on endothelin-1 activation of ERK. The effect of this peptide on ERK activation was determined in ETB receptor cDNA-transfected Chinese hamster ovary cells and in ETA- and ETB-expressing human pulmonary artery smooth muscle cells obtained from a normal and a bone morphogenetic protein-2 receptor, exon 1-8 deletion subject, with pulmonary hypertension. In the Chinese hamster ovary cells the peptide, at optimum 10 μm concentration, suppressed endothelin-1 activation. In the normal human pulmonary artery smooth muscle cells, the peptide marginally enhanced endothelin-1 activation of ERK. However, it markedly enhanced the endothelin-1 activation of ERK in the bone morphogenetic protein-2 receptor human pulmonary artery smooth muscle cells. While the effective concentration for endothelin-1 activation of ERK remained unchanged in the bone morphogenetic protein-2 receptor human pulmonary artery smooth muscle cells, the number of ETB receptors declined by 2/3. These data point to the intracellular third loop peptide as having variable receptor interactive effects with both signal repressive and enhancing capabilities. Peptides that can alter endothelin-1 signal capabilities are potentially important in the study and treatment of pulmonary hypertension.
Collapse
Affiliation(s)
- Christine O Sallum
- Department of Biochemistry, Boston University School of Medicine, MA 02118, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Ahnstedt H, Stenman E, Cao L, Henriksson M, Edvinsson L. Cytokines and growth factors modify the upregulation of contractile endothelin ET(A) and ET(B) receptors in rat cerebral arteries after organ culture. Acta Physiol (Oxf) 2012; 205:266-78. [PMID: 22145714 DOI: 10.1111/j.1748-1716.2011.02392.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 09/20/2011] [Accepted: 11/30/2011] [Indexed: 11/30/2022]
Abstract
AIM Experimental cerebral ischaemia and organ culture of cerebral arteries induce an increased endothelin ET(B) receptor-mediated contraction. The aim of this study was to examine whether cytokines and growth factors, known to be activated in ischaemia, can influence the expression and function of endothelin receptors after organ culture. METHODS Rat middle cerebral arteries were cultured for 24 h at 37 °C in humidified 5% CO(2) and air in culture medium alone, or with tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β), platelet-derived growth factor (PDGF), epidermal growth factor (EGF) or basic fibroblast growth factor (bFGF). Concentration-response curves were obtained for sarafotoxin 6c (ET(B) receptor agonist) and endothelin-1 (here ET(A) receptor agonist, because of ET(B) receptor desensitization). The receptor mRNA expression was examined by real-time PCR and the protein expression by immunohistochemistry and Western blot. RESULTS Tumour necrosis factor-α (100 ng mL(-1) ) and EGF (20 ng mL(-1) ) potentiated the ET(B) receptor-mediated contraction (increase in pEC(50) without change in E(max) ). bFGF (10 ng mL(-1) ) and IL-1β (10 ng mL(-1) ) induced an enhanced ET(A) receptor-mediated contraction. bFGF (10 ng mL(-1) ) significantly increased the ET(B) mRNA level, and EGF (20 ng mL(-1) ) increased the ET(A) receptor protein. Increased ET(B) receptor mRNA and protein level also were observed after treatment with IL-1β (10 ng mL(-1) ). CONCLUSION This study shows that TNF-α, IL-1β, EGF and bFGF can modify the expression and function of endothelin receptors during organ culture. Because there is similar receptor upregulation in experimental stroke, the effect of cytokines and growth factors on endothelin receptor upregulation is an interesting aspect to study in vivo.
Collapse
Affiliation(s)
- H. Ahnstedt
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University; Lund; Sweden
| | - E. Stenman
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University; Lund; Sweden
| | - L. Cao
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University; Lund; Sweden
| | - M. Henriksson
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University; Lund; Sweden
| | - L. Edvinsson
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University; Lund; Sweden
| |
Collapse
|
23
|
Zhang Y, Jose PA, Zeng C. Regulation of sodium transport in the proximal tubule by endothelin. CONTRIBUTIONS TO NEPHROLOGY 2011; 172:63-75. [PMID: 21893989 DOI: 10.1159/000328684] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Human essential hypertension and rodent genetic hypertension are associated with increased sodium transport in the renal proximal tubule and medullary thick ascending limb of Henle. The proximal tubule, which secretes endothelin (ET), expresses the ET(B) receptor. Low (nM) concentrations of ET, via the ET(B) receptor, inhibit sodium and water transport and ATP-driven drug secretion in the proximal tubule. In contrast, very low (pM) and high nM concentrations of ET increase renal proximal sodium transport, but the receptor involved remains to be determined. The natriuretic effect of ET(B) receptor stimulation is impaired in spontaneously hypertensive rats, due in part to a defective interaction with D(3) dopamine and angiotensin II type 1 receptors. Impaired ET(B) receptor function in the renal proximal tubule may be important in the pathogenesis of genetic hypertension.
Collapse
|
24
|
Rapoport RM, Zuccarello M. Endothelin(A)-endothelin(B) receptor cross-talk and endothelin receptor binding. J Pharm Pharmacol 2011; 63:1373-7. [PMID: 21988418 DOI: 10.1111/j.2042-7158.2011.01334.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND OBJECTIVE The magnitude of inhibition of an endothelin (ET)-1 response by selective blockade of the ET(A) or ET(B) receptors can be limited by apparent compensation mediated by the unblocked receptor. While the mechanism underlying this functionally defined interaction, or 'cross-talk', is not clear, binding studies suggest an interaction between the ET receptor subtypes. KEY FINDINGS These binding studies are reviewed and suggest that, in general, they support the hypothesis that ET(A) and ET(B) receptor activation of intracellular signalling pathways influence ET-1 binding to these receptor subtypes. SUMMARY However, the relationship of these binding studies to functional effects and, thus, functional ET(A)-ET(B) receptor cross-talk, remains largely untested.
Collapse
Affiliation(s)
- Robert M Rapoport
- Research Service, Veterans Affairs Medical Center, Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0575, USA.
| | | |
Collapse
|
25
|
Montmayeur JP, Barr TP, Kam SA, Packer SJ, Strichartz GR. ET-1 induced Elevation of intracellular calcium in clonal neuronal and embryonic kidney cells involves endogenous endothelin-A receptors linked to phospholipase C through Gα(q/11). Pharmacol Res 2011; 64:258-67. [PMID: 21515378 DOI: 10.1016/j.phrs.2011.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 04/07/2011] [Accepted: 04/07/2011] [Indexed: 01/23/2023]
Abstract
Endothelin-1 (ET-1) is a pain mediator, elevated in skin after injury, which potentiates noxious thermal and mechanical stimuli (hyperalgesia) through the activation of ET(A) (and, perhaps, ET(B)) receptors on pain fibers. Part of the mechanism underlying this effect has recently been shown to involve potentiation of neuronal TRPV1 by PKCɛ. However, the early steps of this pathway, which are recapitulated in HEK 293 cells co-expressing TRPV1 and ET(A) receptors, remain unexplored. To clarify these steps, we investigated the pharmacological profile and signaling properties of native endothelin receptors in immortalized cell lines including HEK 293 and ND7 model sensory neurons. Previously we showed that in ND7/104, a dorsal root ganglia-derived cell line, ET-1 elicits a rise in intracellular calcium ([Ca(2+)](in)) which is blocked by BQ-123, an ET(A) receptor antagonist, but not by BQ-788, an ET(B) receptor antagonist, suggesting that ET(A) receptors mediate this effect. Here we extend these findings to HEK 293T cells. Examination of the expression of ET(A) and ET(B) receptors by RT-PCR and [(125)I]-ET-1 binding experiments confirms the slight predominance of ET(A) receptor binding sites and messenger RNA in both ND7/104 and HEK 293T cells. In addition, selective agonists of the ET(B) receptor (sarafotoxin 6c, BQ-3020 or IRL-1620) do not induce a transient increase in [Ca(2+)](in). Furthermore, reduction of ET(B) mRNA levels by siRNA does not abrogate calcium mobilization by ET-1 in HEK 293T cells, corroborating the lack of an ET(B) receptor role in this response. However, in HEK 293 cells with low endogenous ET(A) mRNA levels, ET-1 does not induce a transient increase in [Ca(2+)](in). Observation of the [Ca(2+)](in) elevation in ND7/104 and HEK 293T cells in the absence of extracellular calcium suggests that ET-1 elicits a release of calcium from intracellular stores, and pretreatment of the cells with pertussis toxin or a selective inhibitor of phospholipase C (PLC) point to a mechanism involving Gαq/11 coupling. These results are consistent with the hypothesis that a certain threshold of ET(A) receptor expression is necessary to drive a transient [Ca(2+)](in) increase in these cells and that this process involves release of calcium from intracellular stores following Gαq/11 activation.
Collapse
Affiliation(s)
- Jean-Pierre Montmayeur
- Pain Research Center, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham & Women's Hospital, Boston, MA 02115, USA; Centre des Sciences du Goût et de l'Alimentation, UMR6265 CNRS, F-21000 Dijon, France
| | | | | | | | | |
Collapse
|
26
|
Abstract
Since its discovery in 1988 as an endothelial cell-derived peptide that exerts the most potent vasoconstriction of any known endogenous compound, endothelin (ET) has emerged as an important regulator of renal physiology and pathophysiology. This review focuses on how the ET system impacts renal function in health; it is apparent that ET regulates multiple aspects of kidney function. These include modulation of glomerular filtration rate and renal blood flow, control of renin release, and regulation of transport of sodium, water, protons, and bicarbonate. These effects are exerted through ET interactions with almost every cell type in the kidney, including mesangial cells, podocytes, endothelium, vascular smooth muscle, every section of the nephron, and renal nerves. In addition, while not the subject of the current review, ET can also indirectly affect renal function through modulation of extrarenal systems, including the vasculature, nervous system, adrenal gland, circulating hormones, and the heart. As will become apparent, these pleiotropic effects of ET are of fundamental physiologic importance in the control of renal function in health. In addition, to help put these effects into perspective, we will also discuss, albeit to a relatively limited extent, how alterations in the ET system can contribute to hypertension and kidney disease.
Collapse
Affiliation(s)
- Donald E Kohan
- Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah, USA.
| | | | | | | |
Collapse
|
27
|
Kohan DE, Rossi NF, Inscho EW, Pollock DM. Regulation of blood pressure and salt homeostasis by endothelin. Physiol Rev 2011; 91:1-77. [PMID: 21248162 DOI: 10.1152/physrev.00060.2009] [Citation(s) in RCA: 291] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Endothelin (ET) peptides and their receptors are intimately involved in the physiological control of systemic blood pressure and body Na homeostasis, exerting these effects through alterations in a host of circulating and local factors. Hormonal systems affected by ET include natriuretic peptides, aldosterone, catecholamines, and angiotensin. ET also directly regulates cardiac output, central and peripheral nervous system activity, renal Na and water excretion, systemic vascular resistance, and venous capacitance. ET regulation of these systems is often complex, sometimes involving opposing actions depending on which receptor isoform is activated, which cells are affected, and what other prevailing factors exist. A detailed understanding of this system is important; disordered regulation of the ET system is strongly associated with hypertension and dysregulated extracellular fluid volume homeostasis. In addition, ET receptor antagonists are being increasingly used for the treatment of a variety of diseases; while demonstrating benefit, these agents also have adverse effects on fluid retention that may substantially limit their clinical utility. This review provides a detailed analysis of how the ET system is involved in the control of blood pressure and Na homeostasis, focusing primarily on physiological regulation with some discussion of the role of the ET system in hypertension.
Collapse
Affiliation(s)
- Donald E Kohan
- Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah 84132, USA.
| | | | | | | |
Collapse
|
28
|
New perspectives on the endothelin axis in pain. Pharmacol Res 2011; 63:532-40. [PMID: 21352917 DOI: 10.1016/j.phrs.2011.02.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 02/01/2011] [Accepted: 02/02/2011] [Indexed: 01/14/2023]
|
29
|
Abstract
The 21-amino-acid peptide ET-1 (endothelin-1) regulates a diverse array of physiological processes, including vasoconstriction, angiogenesis, nociception and cell proliferation. Most of the effects of ET-1 are associated with an increase in intracellular calcium concentration. The calcium influx and mobilization pathways activated by ET-1, however, vary immensely. The present review begins with the basics of calcium signalling and investigates the different ways intracellular calcium concentration can increase in response to a stimulus. The focus then shifts to ET-1, and discusses how ET receptors mobilize calcium. We also examine how disease alters calcium-dependent responses to ET-1 by discussing changes to ET-1-mediated calcium signalling in hypertension, as there is significant interest in the role of ET-1 in this important disease. A list of unanswered questions regarding ET-mediated calcium signals are also presented, as well as perspectives for future research of calcium mobilization by ET-1.
Collapse
Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA.
| | | |
Collapse
|
30
|
Thorin E, Clozel M. The cardiovascular physiology and pharmacology of endothelin-1. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2010; 60:1-26. [PMID: 21081213 PMCID: PMC3693982 DOI: 10.1016/b978-0-12-385061-4.00001-5] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
One year after the discovery in 1980 that the endothelium was obligatory for acetylcholine to relax isolated arteries, it was clearly shown that the endothelium could also promote contraction. In 1988, Dr Yanagisawa's group identified endothelin-1 (ET-1) as the first endothelium-derived contracting factor. The circulating levels of this short (21 amino acids) peptide were quickly determined in humans and it was reported that in most cardiovascular diseases, circulating levels of ET-1 were increased and ET-1 was then recognized as a likely mediator of pathological vasoconstriction in human. The discovery of two receptor subtypes in 1990, ET(A) and ET(B), permitted optimization of bosentan, which entered clinical development in 1993, and was offered to patients with pulmonary arterial hypertension in 2001. In this report, we discuss the physiological and pathophysiological role of endothelium-derived ET-1, the pharmacology of its two receptors, focusing on the regulation of the vascular tone and as much as possible in humans. The coronary bed will be used as a running example, but references to the pulmonary, cerebral, and renal circulation will also be made. Many of the cardiovascular complications associated with aging and cardiovascular risk factors are initially attributable, at least in part, to endothelial dysfunction, particularly dysregulation of the vascular function associated with an imbalance in the close interdependence of NO and ET-1, in which the implication of the ET(B) receptor may be central.
Collapse
Affiliation(s)
- Eric Thorin
- Department of Surgery, Montreal Heart Institute, Research Center, Université de Montréal, Montreal, Quebec, Canada
| | | |
Collapse
|
31
|
Watts SW. Endothelin receptors: what's new and what do we need to know? Am J Physiol Regul Integr Comp Physiol 2009; 298:R254-60. [PMID: 19907001 DOI: 10.1152/ajpregu.00584.2009] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Receptors are at the heart of how a molecule transmits a signal to a cell. Two receptor classes for endothelin (ET) are recognized, the ET(A) and ET(B) receptors. Intriguing questions have arisen in the field of ET receptor pharmacology, physiology, and function. For example, a host of pharmacological studies support the interaction of the ET(A) and ET(B) receptor in tissues (veins, arteries, bronchus, arterioles, esophagus), but yet few have been able to demonstrate direct ET(A)/ET(B) receptor interaction. Have we modeled this interaction wrong? Do we have a truly selective ET(A) receptor agonist such that we could selectively stimulate this important receptor? What can we learn from the recent phylogenic studies of the ET receptor family? Have we adequately addressed the number of biological molecules with which ET can interact to exert a biological effect? Recent mass spectrometry studies in our laboratory suggest that ET-1 interacts with other hereto unrecognized proteins. Biased ligands (ligands at the same receptor that elicit distinct signaling responses) have been discovered for other receptors. Do these exist for ET receptors and can we take advantage of this possibility in drug design? These and other questions will be posed in this minireview on topics on ET receptors.
Collapse
Affiliation(s)
- Stephanie W Watts
- Dept. of Pharmacology and Toxicology, B445 Life Sciences Bldg., East Lansing, MI 48824-1317, USA.
| |
Collapse
|
32
|
Raymond MN, Robin P, De Zen F, Vilain G, Tanfin Z. Differential endothelin receptor expression and function in rat myometrial cells and leiomyoma ELT3 cells. Endocrinology 2009; 150:4766-76. [PMID: 19628575 PMCID: PMC2754684 DOI: 10.1210/en.2009-0118] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Uterine leiomyoma are the most common benign tumors of the myometrium. We previously identified endothelin (ET)-1 as a proliferative and antiapoptotic factor in Eker rat-derived leiomyoma (ELT3) cells. A major role of ETB receptor in the prosurvival effect was revealed. Here we investigated, in ELT3 and myometrial cells, the respective contribution of ETA and ETB in the proliferative effect of ET-1. In myometrial cells, binding experiments show that ETA is almost exclusively expressed and stimulates phospholipase C (PLC) activity and ERK1/2 phosphorylation and proliferation. In ELT3 cells, ETB is expressed at about the same level as ETA, and the two receptors are differently coupled to Gi protein. The ETB agonist, sarafotoxin S6c, stimulates PLC activity 60% less than ET-1 but is as potent as ET-1 to increase ERK1/2 phosphorylation and induce proliferation. However, the ability of ETA to activate ERK1/2 is observed after ETB desensitization. Although ETA and ETB antagonists partially reduce ET-1 stimulated PLC activity, they are without effect on ET-1-induced ERK1/2 phosphorylation and proliferation. Only the simultaneous use of ETA and ETB antagonists reduces ET-1-triggered ERK1/2 activation. These unconventional properties of ETRs may reveal the existence of functional ETA-ETB heterodimers. Finally, treatment of ELT3 cells with ETB but not ETA-directed small interfering RNA reduces the proliferative effect of ET-1. All the data obtained in ELT3 cells strengthen the relation between ETB overexpression, which decreases the ETA to ETB ratio, and the ability of leiomyoma cells to highly proliferate and resist apoptosis.
Collapse
Affiliation(s)
- Marie-Noëlle Raymond
- Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Centre National de la Recherche Scientifique Unité Mixte de Recherche 8619, 91 405 Orsay Cedex, France
| | | | | | | | | |
Collapse
|
33
|
Abstract
Endothelin-1 (ET-1) mediates physiological responses via endothelin A (ET(A)) and B (ET(B)) receptors, which may form homo- and heterodimers with unknown function. Here, we investigated ET-receptor dimerization using fluorescence resonance energy transfer (FRET) between receptors tagged with CFP (donor) and receptors tagged with tetracysteine-FlAsH (fluorescein arsenical hairpin) (acceptor) expressed in HEK293 cells. FRET efficiencies were 15%, 22%, and 27% for ET(A)/ET(A), ET(B)/ET(B), and ET(A)/ET(B), respectively, and dimerization was further supported by coimmunoprecipitation. For all dimer pairs, the natural but nonselective ligand ET-1 rapidly (<or=30 s) reduced FRET by >50%, but did not detectably reduce coimmunoprecipitation. ET-1 stimulated a transient increase in intracellular Ca(2+) ([Ca(2+)](i)) lasting 1-2 min for both homodimer pairs, and these ET-1 actions on FRET and [Ca(2+)](i) elevation were blocked by the appropriate subtype-selective antagonist. In contrast, ET(A)/ET(B) heterodimers mediated a sustained [Ca(2+)](i) increase lasting >10 min, and required a combination of ET(A) and ET(B) antagonists to block the observed FRET and [Ca(2+)](i) responses. The sensitive CFP/FlAsH FRET assay used here provides new insights into endothelin-receptor dimer function, and represents a unique approach to characterize G-protein-coupled receptor oligomers, including their pharmacology.
Collapse
|