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Pandey KN. Guanylyl cyclase/natriuretic peptide receptor-A: Identification, molecular characterization, and physiological genomics. Front Mol Neurosci 2023; 15:1076799. [PMID: 36683859 PMCID: PMC9846370 DOI: 10.3389/fnmol.2022.1076799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Accepted: 12/02/2022] [Indexed: 01/06/2023] Open
Abstract
The natriuretic peptides (NPs) hormone family, which consists mainly of atrial, brain, and C-type NPs (ANP, BNP, and CNP), play diverse roles in mammalian species, ranging from renal, cardiac, endocrine, neural, and vascular hemodynamics to metabolic regulations, immune responsiveness, and energy distributions. Over the last four decades, new data has transpired regarding the biochemical and molecular compositions, signaling mechanisms, and physiological and pathophysiological functions of NPs and their receptors. NPs are incremented mainly in eliciting natriuretic, diuretic, endocrine, vasodilatory, and neurological activities, along with antiproliferative, antimitogenic, antiinflammatory, and antifibrotic responses. The main locus responsible in the biological and physiological regulatory actions of NPs (ANP and BNP) is the plasma membrane guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA), a member of the growing multi-limbed GC family of receptors. Advances in this field have provided tremendous insights into the critical role of Npr1 (encoding GC-A/NPRA) in the reduction of fluid volume and blood pressure homeostasis, protection against renal and cardiac remodeling, and moderation and mediation of neurological disorders. The generation and use of genetically engineered animals, including gene-targeted (gene-knockout and gene-duplication) and transgenic mutant mouse models has revealed and clarified the varied roles and pleiotropic functions of GC-A/NPRA in vivo in intact animals. This review provides a chronological development of the biochemical, molecular, physiological, and pathophysiological functions of GC-A/NPRA, including signaling pathways, genomics, and gene regulation in both normal and disease states.
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Breinholt VM, Rasmussen CE, Mygind PH, Kjelgaard-Hansen M, Faltinger F, Bernhard A, Zettler J, Hersel U. TransCon CNP, a Sustained-Release C-Type Natriuretic Peptide Prodrug, a Potentially Safe and Efficacious New Therapeutic Modality for the Treatment of Comorbidities Associated with Fibroblast Growth Factor Receptor 3-Related Skeletal Dysplasias. J Pharmacol Exp Ther 2019; 370:459-471. [PMID: 31235532 DOI: 10.1124/jpet.119.258251] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 06/18/2019] [Indexed: 11/22/2022] Open
Abstract
TransCon CNP is a C-type natriuretic peptide (CNP-38) conjugated via a cleavable linker to a polyethylene glycol carrier molecule, designed to provide sustained systemic CNP levels upon weekly subcutaneous administration. TransCon CNP is in clinical development for the treatment of comorbidities associated with achondroplasia. In both mice and cynomolgus monkeys, sustained exposure to CNP via TransCon CNP was more efficacious in stimulating bone growth than intermittent CNP exposure. TransCon CNP was well tolerated with no adverse cardiovascular effects observed at exposure levels exceeding the expected clinical therapeutic exposure. At equivalent dose levels, reductions in blood pressure and/or an increase in heart rate were seen following single subcutaneous injections of the unconjugated CNP-38 molecule or a daily CNP-39 molecule (same amino acid sequence as Vosoritide, USAN:INN). The half-life of the daily CNP-39 molecule in cynomolgus monkey was estimated to be 20 minutes, compared with 90 hours for CNP-38, released from TransCon CNP. C max for the CNP-39 molecule (20 µg/kg) was approximately 100-fold higher, compared with the peak CNP level associated with administration of 100 µg/kg CNP as TransCon CNP. Furthermore, CNP exposure for the daily CNP-39 molecule was only evident for up to 2 hours postdose (lower limit of quantification 37 pmol/l), whereas TransCon CNP gave rise to systemic exposure to CNP-38 for at least 7 days postdose. The prolonged CNP exposure and associated hemodynamically safe peak serum concentrations associated with TransCon CNP administration are suggested to improve efficacy, compared with short-lived CNP molecules, due to better therapeutic drug coverage and decreased risk of hypotension. SIGNIFICANCE STATEMENT: The hormone C-type natriuretic peptide (CNP) is in clinical development for the treatment of comorbidities associated with achondroplasia, the most common form of human dwarfism. The TransCon Technology was used to design TransCon CNP, a prodrug that slowly releases active CNP in the body over several days. Preclinical data show great promise for TransCon CNP to be an effective and well-tolerated drug that provides sustained levels of CNP in a convenient once-weekly dose, while avoiding high systemic CNP bolus concentrations that can induce cardiovascular side effects.
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Affiliation(s)
- Vibeke Miller Breinholt
- Ascendis Pharma A/S, Hellerup, Denmark (V.M.B., C.E.R., P.H.M., M.K.-H.); and Ascendis Pharma GmbH, Heidelberg, Germany (F.F., A.B., J.Z., U.H.)
| | - Caroline E Rasmussen
- Ascendis Pharma A/S, Hellerup, Denmark (V.M.B., C.E.R., P.H.M., M.K.-H.); and Ascendis Pharma GmbH, Heidelberg, Germany (F.F., A.B., J.Z., U.H.)
| | - Per Holse Mygind
- Ascendis Pharma A/S, Hellerup, Denmark (V.M.B., C.E.R., P.H.M., M.K.-H.); and Ascendis Pharma GmbH, Heidelberg, Germany (F.F., A.B., J.Z., U.H.)
| | - Mads Kjelgaard-Hansen
- Ascendis Pharma A/S, Hellerup, Denmark (V.M.B., C.E.R., P.H.M., M.K.-H.); and Ascendis Pharma GmbH, Heidelberg, Germany (F.F., A.B., J.Z., U.H.)
| | - Frank Faltinger
- Ascendis Pharma A/S, Hellerup, Denmark (V.M.B., C.E.R., P.H.M., M.K.-H.); and Ascendis Pharma GmbH, Heidelberg, Germany (F.F., A.B., J.Z., U.H.)
| | - Ana Bernhard
- Ascendis Pharma A/S, Hellerup, Denmark (V.M.B., C.E.R., P.H.M., M.K.-H.); and Ascendis Pharma GmbH, Heidelberg, Germany (F.F., A.B., J.Z., U.H.)
| | - Joachim Zettler
- Ascendis Pharma A/S, Hellerup, Denmark (V.M.B., C.E.R., P.H.M., M.K.-H.); and Ascendis Pharma GmbH, Heidelberg, Germany (F.F., A.B., J.Z., U.H.)
| | - Ulrich Hersel
- Ascendis Pharma A/S, Hellerup, Denmark (V.M.B., C.E.R., P.H.M., M.K.-H.); and Ascendis Pharma GmbH, Heidelberg, Germany (F.F., A.B., J.Z., U.H.)
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Pandey KN. Molecular and genetic aspects of guanylyl cyclase natriuretic peptide receptor-A in regulation of blood pressure and renal function. Physiol Genomics 2018; 50:913-928. [PMID: 30169131 DOI: 10.1152/physiolgenomics.00083.2018] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Natriuretic peptides (NPs) exert diverse effects on several biological and physiological systems, such as kidney function, neural and endocrine signaling, energy metabolism, and cardiovascular function, playing pivotal roles in the regulation of blood pressure (BP) and cardiac and vascular homeostasis. NPs are collectively known as anti-hypertensive hormones and their main functions are directed toward eliciting natriuretic/diuretic, vasorelaxant, anti-proliferative, anti-inflammatory, and anti-hypertrophic effects, thereby, regulating the fluid volume, BP, and renal and cardiovascular conditions. Interactions of NPs with their cognate receptors display a central role in all aspects of cellular, biochemical, and molecular mechanisms that govern physiology and pathophysiology of BP and cardiovascular events. Among the NPs atrial and brain natriuretic peptides (ANP and BNP) activate guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA) and initiate intracellular signaling. The genetic disruption of Npr1 (encoding GC-A/NPRA) in mice exhibits high BP and hypertensive heart disease that is seen in untreated hypertensive subjects, including high BP and heart failure. There has been a surge of interest in the NPs and their receptors and a wealth of information have emerged in the last four decades, including molecular structure, signaling mechanisms, altered phenotypic characterization of transgenic and gene-targeted animal models, and genetic analyses in humans. The major goal of the present review is to emphasize and summarize the critical findings and recent discoveries regarding the molecular and genetic regulation of NPs, physiological metabolic functions, and the signaling of receptor GC-A/NPRA with emphasis on the BP regulation and renal and cardiovascular disorders.
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Affiliation(s)
- Kailash N Pandey
- Department of Physiology, Tulane University Health Sciences Center, School of Medicine , New Orleans, Louisiana
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Endocytosis and Trafficking of Natriuretic Peptide Receptor-A: Potential Role of Short Sequence Motifs. MEMBRANES 2015; 5:253-87. [PMID: 26151885 PMCID: PMC4584282 DOI: 10.3390/membranes5030253] [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: 04/18/2015] [Revised: 06/25/2015] [Accepted: 06/25/2015] [Indexed: 12/19/2022]
Abstract
The targeted endocytosis and redistribution of transmembrane receptors among membrane-bound subcellular organelles are vital for their correct signaling and physiological functions. Membrane receptors committed for internalization and trafficking pathways are sorted into coated vesicles. Cardiac hormones, atrial and brain natriuretic peptides (ANP and BNP) bind to guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA) and elicit the generation of intracellular second messenger cyclic guanosine 3',5'-monophosphate (cGMP), which lowers blood pressure and incidence of heart failure. After ligand binding, the receptor is rapidly internalized, sequestrated, and redistributed into intracellular locations. Thus, NPRA is considered a dynamic cellular macromolecule that traverses different subcellular locations through its lifetime. The utilization of pharmacologic and molecular perturbants has helped in delineating the pathways of endocytosis, trafficking, down-regulation, and degradation of membrane receptors in intact cells. This review describes the investigation of the mechanisms of internalization, trafficking, and redistribution of NPRA compared with other cell surface receptors from the plasma membrane into the cell interior. The roles of different short-signal peptide sequence motifs in the internalization and trafficking of other membrane receptors have been briefly reviewed and their potential significance in the internalization and trafficking of NPRA is discussed.
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Dupré E, Herrou J, Lensink MF, Wintjens R, Vagin A, Lebedev A, Crosson S, Villeret V, Locht C, Antoine R, Jacob-Dubuisson F. Virulence regulation with Venus flytrap domains: structure and function of the periplasmic moiety of the sensor-kinase BvgS. PLoS Pathog 2015; 11:e1004700. [PMID: 25738876 PMCID: PMC4352136 DOI: 10.1371/journal.ppat.1004700] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 01/14/2015] [Indexed: 11/23/2022] Open
Abstract
Two-component systems (TCS) represent major signal-transduction pathways for adaptation to environmental conditions, and regulate many aspects of bacterial physiology. In the whooping cough agent Bordetella pertussis, the TCS BvgAS controls the virulence regulon, and is therefore critical for pathogenicity. BvgS is a prototypical TCS sensor-kinase with tandem periplasmic Venus flytrap (VFT) domains. VFT are bi-lobed domains that typically close around specific ligands using clamshell motions. We report the X-ray structure of the periplasmic moiety of BvgS, an intricate homodimer with a novel architecture. By combining site-directed mutagenesis, functional analyses and molecular modeling, we show that the conformation of the periplasmic moiety determines the state of BvgS activity. The intertwined structure of the periplasmic portion and the different conformation and dynamics of its mobile, membrane-distal VFT1 domains, and closed, membrane-proximal VFT2 domains, exert a conformational strain onto the transmembrane helices, which sets the cytoplasmic moiety in a kinase-on state by default corresponding to the virulent phase of the bacterium. Signaling the presence of negative signals perceived by the periplasmic domains implies a shift of BvgS to a distinct state of conformation and activity, corresponding to the avirulent phase. The response to negative modulation depends on the integrity of the periplasmic dimer, indicating that the shift to the kinase-off state implies a concerted conformational transition. This work lays the bases to understand virulence regulation in Bordetella. As homologous sensor-kinases control virulence features of diverse bacterial pathogens, the BvgS structure and mechanism may pave the way for new modes of targeted therapeutic interventions.
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Affiliation(s)
- Elian Dupré
- Center for Infection and Immunity (CIIL), Institut Pasteur de Lille, Lille, France
- Center for Infection and Immunity (CIIL), University Lille North of France, Lille, France
- UMR 8204, Centre National de la Recherche Scientifique (CNRS), Lille, France
- U1019, Institut National de la Santé et de la Recherche Médicale (INSERM), Lille, France
| | - Julien Herrou
- Center for Infection and Immunity (CIIL), Institut Pasteur de Lille, Lille, France
- Center for Infection and Immunity (CIIL), University Lille North of France, Lille, France
- UMR 8204, Centre National de la Recherche Scientifique (CNRS), Lille, France
- U1019, Institut National de la Santé et de la Recherche Médicale (INSERM), Lille, France
| | - Marc F. Lensink
- Unité de Glycobiologie Structurale et Fonctionnelle, CNRS UMR8576, University Lille North of France, Villeneuve d’Ascq, France
| | - René Wintjens
- Laboratory of Biopolymers and Supramolecular Nanomaterials, Université Libre de Bruxelles, Brussels, Belgium
| | - Alexey Vagin
- Structural Biology Laboratory, University of York, York, England, United Kingdom
| | - Andrey Lebedev
- Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Didcot, England, United Kingdom
| | - Sean Crosson
- Department of Biochemistry & Molecular Biology, University of Chicago, Chicago, Illinois, United States of America
| | - Vincent Villeret
- Unité de Glycobiologie Structurale et Fonctionnelle, CNRS UMR8576, University Lille North of France, Villeneuve d’Ascq, France
| | - Camille Locht
- Center for Infection and Immunity (CIIL), Institut Pasteur de Lille, Lille, France
- Center for Infection and Immunity (CIIL), University Lille North of France, Lille, France
- UMR 8204, Centre National de la Recherche Scientifique (CNRS), Lille, France
- U1019, Institut National de la Santé et de la Recherche Médicale (INSERM), Lille, France
| | - Rudy Antoine
- Center for Infection and Immunity (CIIL), Institut Pasteur de Lille, Lille, France
- Center for Infection and Immunity (CIIL), University Lille North of France, Lille, France
- UMR 8204, Centre National de la Recherche Scientifique (CNRS), Lille, France
- U1019, Institut National de la Santé et de la Recherche Médicale (INSERM), Lille, France
| | - Françoise Jacob-Dubuisson
- Center for Infection and Immunity (CIIL), Institut Pasteur de Lille, Lille, France
- Center for Infection and Immunity (CIIL), University Lille North of France, Lille, France
- UMR 8204, Centre National de la Recherche Scientifique (CNRS), Lille, France
- U1019, Institut National de la Santé et de la Recherche Médicale (INSERM), Lille, France
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Vink S, Jin A, Poth K, Head G, Alewood P. Natriuretic peptide drug leads from snake venom. Toxicon 2012; 59:434-45. [DOI: 10.1016/j.toxicon.2010.12.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Accepted: 12/01/2010] [Indexed: 10/18/2022]
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Sukumaran M, Rossmann M, Shrivastava I, Dutta A, Bahar I, Greger IH. Dynamics and allosteric potential of the AMPA receptor N-terminal domain. EMBO J 2011; 30:972-82. [PMID: 21317871 DOI: 10.1038/emboj.2011.17] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 01/10/2011] [Indexed: 01/13/2023] Open
Abstract
Glutamate-gated ion channels (ionotropic glutamate receptors, iGluRs) sense the extracellular milieu via an extensive extracellular portion, comprised of two clamshell-shaped segments. The distal, N-terminal domain (NTD) has allosteric potential in NMDA-type iGluRs, which has not been ascribed to the analogous domain in AMPA receptors (AMPARs). In this study, we present new structural data uncovering dynamic properties of the GluA2 and GluA3 AMPAR NTDs. GluA3 features a zipped-open dimer interface with unconstrained lower clamshell lobes, reminiscent of metabotropic GluRs (mGluRs). The resulting labile interface supports interprotomer rotations, which can be transmitted to downstream receptor segments. Normal mode analysis reveals two dominant mechanisms of AMPAR NTD motion: intraprotomer clamshell motions and interprotomer counter-rotations, as well as accessible interconversion between AMPAR and mGluR conformations. In addition, we detect electron density for a potential ligand in the GluA2 interlobe cleft, which may trigger lobe motions. Together, these data support a dynamic role for the AMPAR NTDs, which widens the allosteric landscape of the receptor and could provide a novel target for ligand development.
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Affiliation(s)
- Madhav Sukumaran
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
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Alli AA, Gower WR. Molecular approaches to examine the phosphorylation state of the C type natriuretic peptide receptor. J Cell Biochem 2010; 110:985-94. [PMID: 20564198 DOI: 10.1002/jcb.22612] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The intracellular domain of the C type natriuretic peptide receptor (NPRC) contains one threonine and several serine residues where phosphorylation is thought to occur. Several phosphorylation consensus sequences for various kinases have been identified within the intracellular domain of NPRC, but the exact residues that are phosphorylated and the specific kinases responsible for their phosphorylation have not been thoroughly defined. Here we introduce a recombinant GST fusion protein and a rat gastric mucosa (RGM1) cell line as molecular tools to study the phosphorylation state of NPRC in vitro and in vivo, respectively. We utilize a previously characterized polyclonal antibody against NPRC to probe for total NPRC protein and various phosphospecific and substrate motif antibodies to probe for phosphorylation of NPRC. Phosphoprotein staining reagents were used with a phosphoprotein control set to detect phosphorylation of NPRC at serine and threonine residues. Recombinant GST-NPRC fusion protein was phosphorylated in vitro by RGM1 lysate in the presence of adenosine-5'-triphosphate (ATP). Western blot analysis using a monoclonal phospho-Thr antibody, which exclusively detects phosphorylated threonine residues, and does not cross-react with phosphorylated serine residues revealed NPRC immunoprecipitated from RGM1 lysate is phosphorylated on a threonine residue. Global analysis of the entire rat NPRC sequence using a protein kinase A (PKA) prediction algorithm, identified five putative PKA phosphorylation sites containing a serine residue and one containing a threonine residue, Thr 505. Taken together, the data presented here suggest that rat NPRC is a substrate for PKA and Thr 505 located within the intracellular domain of NPRC is a likely candidate site for the phosphorylation.
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Affiliation(s)
- Abdel A Alli
- Research Service, James A. Haley Veterans Hospital, Tampa, Florida 33612, USA
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Molecular dynamics investigation of cyclic natriuretic peptides: Dynamic properties reflect peptide activity. J Mol Graph Model 2010; 28:834-41. [DOI: 10.1016/j.jmgm.2010.03.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 03/01/2010] [Accepted: 03/02/2010] [Indexed: 11/22/2022]
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Pandey KN. Ligand-mediated endocytosis and intracellular sequestration of guanylyl cyclase/natriuretic peptide receptors: role of GDAY motif. Mol Cell Biochem 2010; 334:81-98. [PMID: 19941037 PMCID: PMC4316816 DOI: 10.1007/s11010-009-0332-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Accepted: 11/04/2009] [Indexed: 12/31/2022]
Abstract
The guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA), also referred to as GC-A, is a single polypeptide molecule having a critical function in blood pressure regulation and cardiovascular homeostasis. GC-A/NPRA, which resides in the plasma membrane, consists of an extracellular ligand-binding domain, a single transmembrane domain, and an intracellular cytoplasmic region containing a protein kinase-like homology domain (KHD) and a guanylyl cyclase (GC) catalytic domain. After binding with atrial and brain natriuretic peptides (ANP and BNP), GC-A/NPRA is internalized and sequestered into intracellular compartments. Therefore, GC-A/NPRA is a dynamic cellular macromolecule that traverses different subcellular compartments through its lifetime. This review describes the roles of short-signal sequences in the internalization, trafficking, and intracellular redistribution of GC-A/NPRA from cell surface to cell interior. Evidence indicates that, after internalization, the ligand-receptor complexes dissociate inside the cell and a population of GC-A/NPRA recycles back to the plasma membrane. Subsequently, the disassociated ligands are degraded in the lysosomes. However, a small percentage of the ligand escapes the lysosomal degradative pathway, and is released intact into culture medium. Using pharmacologic and molecular perturbants, emphasis has been placed on the cellular regulation and processing of ligand-bound GC-A/NPRA in terms of receptor trafficking and down-regulation in intact cells. The discussion is concluded by examining the functions of short-signal sequence motifs in the cellular life-cycle of GC-A/NPRA, including endocytosis, trafficking, metabolic processing, inactivation, and/or down-regulation in model cell systems.
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Affiliation(s)
- Kailash N Pandey
- Department of Physiology, Tulane University School of Medicine, SL-39 1430 Tulane Ave, New Orleans, LA 70112, USA.
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Natriuretic Peptides and Cardiovascular Regulation. Cardiovasc Endocrinol 2008. [DOI: 10.1007/978-1-59745-141-3_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Kovacic P, Pozos RS, Draskovich CD. Unifying electrostatic mechanism for receptor-ligand activity. J Recept Signal Transduct Res 2008; 27:411-31. [PMID: 18097940 DOI: 10.1080/10799890701699686] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
A prior article in skeletal form proposed an electrostatic mechanism for receptor-ligand activity. The present review provides an elaboration, including supporting evidence. The fundamental aspect entails the presence of molecular electrostatic potential associated with ions and dipoles in the ligand. The ligand can be regarded as an electrical link that joins prevalent electrostatic fields present in the surrounding protein matrix. The exact role of these fields is speculative. One possibility is to function as conduits for electrons and radicals in cell signaling. There is increasing support for important participation of these species in signal transduction. There might also be a favorable influence on energetics involving the electron transfer process. A summary of receptor biology is also provided, including receptors for acetylcholine (nicotinic and muscarinic), GABA, adrenergic, and glutamate.
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Affiliation(s)
- Peter Kovacic
- Department of Chemistry, San Diego State University, San Diego, California 921812, USA.
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Castel H, Diallo M, Chatenet D, Leprince J, Desrues L, Schouft MT, Fontaine M, Dubessy C, Lihrmann I, Scalbert E, Malagon M, Vaudry H, Tonon MC, Gandolfo P. Biochemical and functional characterization of high-affinity urotensin II receptors in rat cortical astrocytes. J Neurochem 2006; 99:582-95. [PMID: 16942596 DOI: 10.1111/j.1471-4159.2006.04130.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The urotensin II (UII) gene is primarily expressed in the central nervous system, but the functions of UII in the brain remain elusive. Here, we show that cultured rat astrocytes constitutively express the UII receptor (UT). Saturation and competition experiments performed with iodinated rat UII ([(125)I]rUII) revealed the presence of high- and low-affinity binding sites on astrocytes. Human UII (hUII) and the two highly active agonists hUII(4-11) and [3-iodo-Tyr9]hUII(4-11) were also very potent in displacing [(125)I]rUII from its binding sites, whereas the non-cyclic analogue [Ser5,10]hUII(4-11) and somatostatin-14 could only displace [(125)I]rUII binding at micromolar concentrations. Reciprocally, rUII failed to compete with [(125)I-Tyr0,D-Trp8]somatostatin-14 binding on astrocytes. Exposure of cultured astrocytes to rUII stimulated [(3)H]inositol incorporation and increased intracellular Ca(2+) concentration in a dose-dependent manner. The stimulatory effect of rUII on polyphosphoinositide turnover was abolished by the phospholipase C inhibitor U73122, but only reduced by 56% by pertussis toxin. The GTP analogue Gpp(NH)p caused its own biphasic displacement of [(125)I]rUII binding and provoked an affinity shift of the competition curve of rUII. Pertussis toxin shifted the competition curve towards a single lower affinity state. Taken together, these data demonstrate that rat astrocytes express high- and low-affinity UII binding sites coupled to G proteins, the high-affinity receptor exhibiting the same pharmacological and functional characteristics as UT.
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Affiliation(s)
- Hélène Castel
- INSERM, Laboratory of Cellular and Molecular Neuroendocrinology, European Institute for Peptide Research, University of Rouen, Mont-Saint-Aignan, France
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