1
|
Tao YX. Molecular chaperones and G protein-coupled receptor maturation and pharmacology. Mol Cell Endocrinol 2020; 511:110862. [PMID: 32389798 DOI: 10.1016/j.mce.2020.110862] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 12/15/2022]
Abstract
G protein-coupled receptors (GPCRs) are highly conserved versatile signaling molecules located at the plasma membrane that respond to diverse extracellular signals. They regulate almost all physiological processes in the vertebrates. About 35% of current drugs target these receptors. Mutations in these genes have been identified as causes of numerous diseases. The seven transmembrane domain structure of GPCRs implies that the folding of these transmembrane proteins is extremely complicated and difficult. Indeed, many wild type GPCRs are not folded optimally. The most common defect in genetic diseases caused by GPCR mutations is misfolding and failure to reach the plasma membrane where it functions. General molecular chaperones aid the folding of all proteins, including GPCRs, by preventing aggregation, promoting folding and disaggregating small aggregates. Some GPCRs need additional receptor-specific chaperones to assist their folding. Many of these receptor-specific chaperones interact with additional receptors and alter receptor pharmacology, expanding the understanding of these chaperone proteins.
Collapse
Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, 36849-5519, USA.
| |
Collapse
|
2
|
Muttenthaler M, Andersson Å, Vetter I, Menon R, Busnelli M, Ragnarsson L, Bergmayr C, Arrowsmith S, Deuis JR, Chiu HS, Palpant NJ, O'Brien M, Smith TJ, Wray S, Neumann ID, Gruber CW, Lewis RJ, Alewood PF. Subtle modifications to oxytocin produce ligands that retain potency and improved selectivity across species. Sci Signal 2017; 10:10/508/eaan3398. [PMID: 29208680 DOI: 10.1126/scisignal.aan3398] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Oxytocin and vasopressin mediate various physiological functions that are important for osmoregulation, reproduction, cardiovascular function, social behavior, memory, and learning through four G protein-coupled receptors that are also implicated in high-profile disorders. Targeting these receptors is challenging because of the difficulty in obtaining ligands that retain selectivity across rodents and humans for translational studies. We identified a selective and more stable oxytocin receptor (OTR) agonist by subtly modifying the pharmacophore framework of human oxytocin and vasopressin. [Se-Se]-oxytocin-OH displayed similar potency to oxytocin but improved selectivity for OTR, an effect that was retained in mice. Centrally infused [Se-Se]-oxytocin-OH potently reversed social fear in mice, confirming that this action was mediated by OTR and not by V1a or V1b vasopressin receptors. In addition, [Se-Se]-oxytocin-OH produced a more regular contraction pattern than did oxytocin in a preclinical labor induction and augmentation model using myometrial strips from cesarean sections. [Se-Se]-oxytocin-OH had no activity in human cardiomyocytes, indicating a potentially improved safety profile and therapeutic window compared to those of clinically used oxytocin. In conclusion, [Se-Se]-oxytocin-OH is a novel probe for validating OTR as a therapeutic target in various biological systems and is a promising new lead for therapeutic development. Our medicinal chemistry approach may also be applicable to other peptidergic signaling systems with similar selectivity issues.
Collapse
Affiliation(s)
- Markus Muttenthaler
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia. .,Faculty of Chemistry, Institute of Biological Chemistry, University of Vienna, 1090 Vienna, Austria
| | - Åsa Andersson
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Irina Vetter
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.,School of Pharmacy, The University of Queensland, Brisbane, Queensland 4104, Australia
| | - Rohit Menon
- Department of Behavioral and Molecular Neurobiology, Regensburg Center of Neuroscience, University of Regensburg, 93053 Regensburg, Germany
| | - Marta Busnelli
- CNR-Institute of Neuroscience, 20129 Milan, Italy.,Department of Biotechnology and Translational Medicine, University of Milan, 20129 Milan, Italy
| | - Lotten Ragnarsson
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Christian Bergmayr
- Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Sarah Arrowsmith
- Department of Cellular and Molecular Physiology, Harris-Wellbeing Preterm Birth Centre, Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, UK
| | - Jennifer R Deuis
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Han Sheng Chiu
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Nathan J Palpant
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Margaret O'Brien
- National Centre for Biomedical Engineering Science, National University of Ireland, Galway H91 CF50, Ireland
| | - Terry J Smith
- National Centre for Biomedical Engineering Science, National University of Ireland, Galway H91 CF50, Ireland
| | - Susan Wray
- Department of Cellular and Molecular Physiology, Harris-Wellbeing Preterm Birth Centre, Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, UK
| | - Inga D Neumann
- Department of Behavioral and Molecular Neurobiology, Regensburg Center of Neuroscience, University of Regensburg, 93053 Regensburg, Germany
| | - Christian W Gruber
- Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria.,School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Richard J Lewis
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Paul F Alewood
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.
| |
Collapse
|
3
|
Tao YX, Conn PM. Chaperoning G protein-coupled receptors: from cell biology to therapeutics. Endocr Rev 2014; 35:602-47. [PMID: 24661201 PMCID: PMC4105357 DOI: 10.1210/er.2013-1121] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 03/14/2014] [Indexed: 12/13/2022]
Abstract
G protein-coupled receptors (GPCRs) are membrane proteins that traverse the plasma membrane seven times (hence, are also called 7TM receptors). The polytopic structure of GPCRs makes the folding of GPCRs difficult and complex. Indeed, many wild-type GPCRs are not folded optimally, and defects in folding are the most common cause of genetic diseases due to GPCR mutations. Both general and receptor-specific molecular chaperones aid the folding of GPCRs. Chemical chaperones have been shown to be able to correct the misfolding in mutant GPCRs, proving to be important tools for studying the structure-function relationship of GPCRs. However, their potential therapeutic value is very limited. Pharmacological chaperones (pharmacoperones) are potentially important novel therapeutics for treating genetic diseases caused by mutations in GPCR genes that resulted in misfolded mutant proteins. Pharmacoperones also increase cell surface expression of wild-type GPCRs; therefore, they could be used to treat diseases that do not harbor mutations in GPCRs. Recent studies have shown that indeed pharmacoperones work in both experimental animals and patients. High-throughput assays have been developed to identify new pharmacoperones that could be used as therapeutics for a number of endocrine and other genetic diseases.
Collapse
Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology, and Pharmacology (Y.-X.T.), College of Veterinary Medicine, Auburn University, Auburn, Alabama 36849-5519; and Departments of Internal Medicine and Cell Biology (P.M.C.), Texas Tech University Health Science Center, Lubbock, Texas 79430-6252
| | | |
Collapse
|
4
|
Use of Kikume green-red fusions to study the influence of pharmacological chaperones on trafficking of G protein-coupled receptors. FEBS Lett 2012; 586:784-91. [DOI: 10.1016/j.febslet.2012.01.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 01/17/2012] [Accepted: 01/22/2012] [Indexed: 11/22/2022]
|
5
|
Chen S, Webber MJ, Vilardaga JP, Khatri A, Brown D, Ausiello DA, Lin HY, Bouley R. Visualizing microtubule-dependent vasopressin type 2 receptor trafficking using a new high-affinity fluorescent vasopressin ligand. Endocrinology 2011; 152:3893-904. [PMID: 21828182 PMCID: PMC3176653 DOI: 10.1210/en.2011-1049] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The vasopressin receptor type 2 (V2R) is the major target of vasopressin (VP) in renal epithelial cells. Although it is known that VP induces V2R internalization, accumulation in the perinuclear area, and degradation, the V2R intracellular trafficking pathways remain elusive. We visualized this process by developing a new fluorescent VP analog tagged by tetramethylrhodamine (TMR)-[Lys-(PEG)(2)-Suc-TMR(8)]VP or (VP(TMR)). This ligand is fully functional as revealed by its high binding affinity toward V2R [(K(d)) =157 ± 52 nM] and ability to increase intracellular cAMP 32-fold. VP(TMR) induced V2R internalization in LLC-PK1 cells expressing either a FLAG-tagged receptor (FLAG-V2R) or V2R C-terminally tagged with green fluorescent protein (GFP) (V2R-GFP). After internalization, VP(TMR) and V2R-GFP colocalized in the perinuclear area, suggesting that the hormone and receptor traffic along the same pathway. VP(TMR) and V2R colocalized initially with the early endosome markers EEA1 and Rab5, and later with the recycling and late endosome markers Rab11 and Rab25. Epifluorescence microscopy of LLC-PK1 cells expressing GFP-tagged microtubules (MT) showed that VP(TMR)-containing vesicles travel along the MT network, and even remain attached to MT during the metaphase and anaphase of mitosis. Colchicine, a MT-depolymerizing agent, abolished perinuclear accumulation of VP(TMR), and Western blot analysis showed that VP-induced V2R-GFP degradation is markedly retarded, but not abolished, by colchicine (10 μM). We conclude that the new VP(TMR) ligand is suitable for dissecting V2R and VP internalization and trafficking in cells, and that V2R trafficking and down-regulation is an MT-dependent mechanism.
Collapse
Affiliation(s)
- Sylvia Chen
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA
| | | | | | | | | | | | | | | |
Collapse
|
6
|
Faerch M, Christensen JH, Rittig S, Johansson JO, Gregersen N, de Zegher F, Corydon TJ. Diverse vasopressin V2 receptor functionality underlying partial congenital nephrogenic diabetes insipidus. Am J Physiol Renal Physiol 2009; 297:F1518-25. [PMID: 19812297 DOI: 10.1152/ajprenal.00331.2009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
X-linked congenital nephrogenic diabetes insipidus (CNDI) is characterized by a defective renal response to the antidiuretic hormone (AVP) due to variations in the arginine vasopressin receptor 2 (AVPR2) gene. In a unique group of patients, the renal insensitivity to the effects of AVP is incomplete resulting in a partial phenotype. To investigate the molecular defects, two previously published variations in the AVPR2 gene, known to cause a partial CNDI phenotype, were expressed in transiently transfected human embryonic kidney cells. One variation (p.Arg104Cys) is located in the first extracellular loop and the other variation (p.Ser329Arg) is located in the intracellular COOH terminal of the receptor protein. Western blotting showed almost equal amounts of WT-V2R and Arg104Cys-V2R protein at steady state, whereas the level of Ser329Arg-V2R protein was lower. Confocal microscopy established that WT-V2R and Arg104Cys-V2R are localized on the cellular surface while the Ser329Arg-V2R primarily accumulates within the endoplasmic reticulum resulting in reduced surface expression. Ligand binding analysis demonstrated that the B(max) for cells expressing Arg104Cys-V2R and Ser329Arg-V2R were 14.8- and 2.5-fold lower than B(max) for WT-V2R, respectively. AVP affinity (1/K(d)) for WT-V2R and the Ser329Arg-V2R was similar while 1/K(d) for Arg104Cys-V2R was increased. cAMP assay revealed that cells expressing p.Arg104Cys-V2R or p.Ser329Arg-V2R produced 1.7- and 6.8-fold lower amounts of cAMP compared with WT-V2R, respectively. In conclusion, ligand binding and signal transduction capability are dependent on localization of the amino acid variation. Striking divergences at the level of receptor functionality may thus underlie similar clinical phenotypes in CNDI.
Collapse
Affiliation(s)
- Mia Faerch
- Department of Pediatrics, Aarhus University Hospital, Skejby, Denmark.
| | | | | | | | | | | | | |
Collapse
|
7
|
Jean-Alphonse F, Perkovska S, Frantz MC, Durroux T, Méjean C, Morin D, Loison S, Bonnet D, Hibert M, Mouillac B, Mendre C. Biased agonist pharmacochaperones of the AVP V2 receptor may treat congenital nephrogenic diabetes insipidus. J Am Soc Nephrol 2009; 20:2190-203. [PMID: 19729439 DOI: 10.1681/asn.2008121289] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
X-linked congenital nephrogenic diabetes insipidus (cNDI) results from inactivating mutations of the human arginine vasopressin (AVP) V2 receptor (hV(2)R). Most of these mutations lead to intracellular retention of the hV(2)R, preventing its interaction with AVP and thereby limiting water reabsorption and concentration of urine. Because the majority of cNDI-hV(2)Rs exhibit protein misfolding, molecular chaperones hold promise as therapeutic agents; therefore, we sought to identify pharmacochaperones for hV(2)R that also acted as agonists. Here, we describe high-affinity nonpeptide compounds that promoted maturation and membrane rescue of L44P, A294P, and R337X cNDI mutants and restored a functional AVP-dependent cAMP signal. Contrary to pharmacochaperone antagonists, these compounds directly activated a cAMP signal upon binding to several cNDI mutants. In addition, these molecules displayed original functionally selective properties (biased agonism) toward the hV(2)R, being unable to recruit arrestin, trigger receptor internalization, or stimulate mitogen-activated protein kinases. These characteristics make these hV(2)R agonist pharmacochaperones promising therapeutic candidates for cNDI.
Collapse
Affiliation(s)
- Frédéric Jean-Alphonse
- CNRS UMR 5203, Institut de Génomique fonctionnelle, INSERM U661, and Université Montpellier I and II, Montpellier, France
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Pérez Oliva AB, Fernéndez LP, Detorre C, Herráiz C, Martínez-Escribano JA, Benítez J, Lozano Teruel JA, García-Borrón JC, Jiménez-Cervantes C, Ribas G. Identification and functional analysis of novel variants of the human melanocortin 1 receptor found in melanoma patients. Hum Mutat 2009; 30:811-22. [PMID: 19338054 DOI: 10.1002/humu.20971] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The melanocortin 1 receptor, a Gs protein-coupled receptor expressed in epidermal melanocytes, is a major determinant of skin pigmentation and phototype and an important contributor to melanoma risk. MC1R activation stimulates synthesis of black, strongly photoprotective eumelanin pigments. Several MC1R alleles are associated with red hair, fair skin, increased sensitivity to ultraviolet radiation, and increased skin cancer risk. The MC1R gene is highly polymorphic, but only a few naturally occurring alleles have been functionally characterized, which complicates the establishment of accurate correlations between the signaling properties of mutant alleles and defined cutaneous phenotypes. We report the functional characterization of six MC1R alleles found in Spanish melanoma patients. Two variants (c.152T>C, p.Val51Ala and c.865T>C, p.Cys289Arg) have never been described, and the others (c.112G>A, p.Val38Met; c.122C>T, p.Ser41Phe; c.383T>C, p.Met128Thr; and c.842A>G, p.Asn281Ser) have not been analyzed for function. p.Asn281Ser corresponds to a functionally silent polymorphism. The other mutations are associated with varying degrees of loss of function (LOF), from moderate decreases in coupling to the cAMP pathway (p.Val38Met and p.Val51Ala) to nearly complete absence of functional coupling (p.Ser41Phe, p.Met128Thr, and p.Cys289Arg). The LOF p.Met128Thr and p.Cys289Arg mutants are trafficked to the cell surface, but are unable to bind agonists efficiently. Conversely, LOF of p.Val38Met, p.Ser41Phe, and p.Val51Ala is due to reduced cell surface expression as a consequence of retention in the endoplasmic reticulum (ER). Therefore, LOF of MC1R alleles is frequently associated with aberrant forward trafficking and accumulation within the ER or with inability to bind properly the activatory ligand.
Collapse
Affiliation(s)
- Ana B Pérez Oliva
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Murcia, Murcia, Spain
| | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Fenton RA, Brønd L, Nielsen S, Praetorius J. Cellular and subcellular distribution of the type-2 vasopressin receptor in the kidney. Am J Physiol Renal Physiol 2007; 293:F748-60. [PMID: 17553938 DOI: 10.1152/ajprenal.00316.2006] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Arginine vasopressin (AVP) is essential for maintaining body fluid homeostasis. The antidiuretic effects of AVP are initialized by binding of AVP to the type-2 vasopressin receptor (V2R) in the kidney collecting duct (CD), resulting in the exocytic insertion of aquaporin-2 (AQP-2) water channels into the apical plasma membrane. In this study, we describe the generation and characterization of a polyclonal antibody targeted against the NH2 terminus of the rat V2R. HEK-293 cells overexpressing the rat, mouse, or human V2R showed strong intracellular immunolabeling. Additionally, immunostaining of M-1 kidney cells expressing a V2R-green fluorescent protein (GFP) fusion construct showed colocalization between GFP and antibody-specific V2R labeling. Immunoblots of rat kidney showed 43- and 47-kDa proteins in all zones that were both reduced to 34-kDa by N-glycosidase F. Protein solubilization with nonionic detergents or the use of homobifunctional cross-linkers demonstrated that the rat V2R exists as a protein complex in native kidney. Immunohistochemistry of rat and mouse kidney revealed abundant labeling of the CD. Double-labeling confocal immunofluorescence microscopy [using distal convoluted tubule/connecting tubule (CNT)-specific marker calbindin and CNT/CD-specific marker AQP-2] showed V2R labeling in both CD and CNT. There was a complete absence of labeling in vascular structures and other renal tubules, including the thick ascending limb (TAL), although RT-PCR of microdissected tubules showed expression of V2R mRNA in TAL. Confocal microscopy demonstrated that at the subcellular level, V2R labeling was predominantly intracellular in normal kidneys, although some staining was apparent in basolateral membrane domains. Confocal microscopy of isolated inner medullary collecting duct tubules showed that the V2R is expressed both intracellularly and in basolateral membrane domains.
Collapse
Affiliation(s)
- Robert A Fenton
- The Water and Salt Research Center, Institute of Anatomy, University of Aarhus, Aarhus, Denmark.
| | | | | | | |
Collapse
|
10
|
Thielen A, Oueslati M, Hermosilla R, Krause G, Oksche A, Rosenthal W, Schülein R. The hydrophobic amino acid residues in the membrane-proximal C tail of the G protein-coupled vasopressin V2 receptor are necessary for transport-competent receptor folding. FEBS Lett 2005; 579:5227-35. [PMID: 16162341 DOI: 10.1016/j.febslet.2005.08.043] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Accepted: 08/16/2005] [Indexed: 11/26/2022]
Abstract
It is believed that the membrane-proximal C tail of the G protein-coupled receptors forms an additional alpha helix with amphipathic properties (helix 8). It was previously shown for the vasopressin V2 receptor (V2R) that a conserved dileucine motif (L(339), L(340)) in this putative helix 8 is necessary for endoplasmic reticulum (ER) to Golgi transfer of the receptor. Here, we demonstrate that the other hydrophobic residues forming the non-polar side of this helix (F(328), V(332) and L(336)) are also transport-relevant. In contrast, the multiple serine residues contributing to the more hydrophilic side (S(330), S(331), S(333), S(334), S(338)) do not influence receptor trafficking. In addition, we show unambiguously by the use of pharmacological chaperones that the hydrophobic residues of the putative helix 8 do not form a transport signal necessary for receptor sorting into ER to Golgi vesicles. Instead, they are necessary to establish a transport-competent folding state in the early secretory pathway.
Collapse
Affiliation(s)
- Anja Thielen
- Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | | | | | | | | | | | | |
Collapse
|
11
|
Sarmiento JM, Ehrenfeld P, Añazco CC, Reyes CE, Troncoso S, Figueroa CD, Müller-Esterl W, González CB. Differential distribution of the vasopressin V2 receptor along the rat nephron during renal ontogeny and maturation. Kidney Int 2005; 68:487-96. [PMID: 16014025 DOI: 10.1111/j.1523-1755.2005.00426.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Ontogeny and cellular distribution of vasopressin receptors in the kidney are key factors determining the role of vasopressin in renal physiology. Expression of vasopressin V(2) receptor (V(2)R) mRNA and the immunoreactive protein in rat kidney were investigated. METHODS An antiserum directed to epitope TLD25 of the rat V(2)R sequence was characterized by Western blotting. Expression of V(2)R mRNA was assessed by reverse transcription-polymerase chain reaction (RT-PCR), and on protein level by immunohistochemistry. RESULTS Specificity of the antiserum was documented by Western blots from cells expressing a fusion protein of V(2)R and GFP. Using lysates of rat kidney and of native cell lines expressing V(2)R but not V(1)R, our antiserum to peptide TLD25 revealed a major band of 55 kD corresponding to the monomeric form of V(2)R, and a band of 110 kD most likely representing the homodimeric form of the receptor. This highly specific antiserum allowed us to localize the V(2)R in thick ascending limbs, distal convoluted and connecting tubules, and in collecting ducts. During ontogeny, immunoreactivity was first observed at the luminal membrane on prenatal day 20, emerging at the basolateral side from postnatal day 5 on. RT-PCR demonstrated V(2)R transcripts from prenatal day 18 to gradually increasing thereafter. CONCLUSION Expression of V(2)R is first detectable in the late embryonic stage of rat ontogeny starting from day E18 and gradually increasing with kidney maturation. In the adult kidney, V(2)R is differentially distributed in the various nephron segments.
Collapse
MESH Headings
- Age Factors
- Animals
- Antibody Specificity
- Cell Membrane/metabolism
- Female
- Gene Expression Regulation, Developmental
- Gestational Age
- Immunohistochemistry
- Kidney Tubules, Collecting/embryology
- Kidney Tubules, Collecting/physiology
- Kidney Tubules, Distal/embryology
- Kidney Tubules, Distal/physiology
- Loop of Henle/embryology
- Loop of Henle/physiology
- Male
- Nephrons/embryology
- Nephrons/physiology
- Pregnancy
- RNA, Messenger/analysis
- Rats
- Rats, Sprague-Dawley
- Receptors, Vasopressin/genetics
- Receptors, Vasopressin/immunology
- Receptors, Vasopressin/metabolism
Collapse
Affiliation(s)
- José M Sarmiento
- Institutos de Fisiología and Histología y Patología, Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Wüller S, Wiesner B, Löffler A, Furkert J, Krause G, Hermosilla R, Schaefer M, Schülein R, Rosenthal W, Oksche A. Pharmacochaperones Post-translationally Enhance Cell Surface Expression by Increasing Conformational Stability of Wild-type and Mutant Vasopressin V2 Receptors. J Biol Chem 2004; 279:47254-63. [PMID: 15319430 DOI: 10.1074/jbc.m408154200] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Some membrane-permeable antagonists restore cell surface expression of misfolded receptors retained in the endoplasmic reticulum (ER) and are therefore termed pharmacochaperones. Whether pharmacochaperones increase protein stability, thereby preventing rapid degradation, or assist folding via direct receptor interactions or interfere with quality control components remains elusive. We now show that the cell surface expression and function (binding of the agonist) of the mainly ER-retained wild-type murine vasopressin V2 receptor GFP fusion protein (mV2R.GFP) is restored by the vasopressin receptor antagonists SR49059 and SR121463B with EC50 values similar to their KD values. This effect was preserved when protein synthesis was abolished. In addition, SR121463B rescued eight mutant human V2Rs (hV2Rs, three are responsible for nephrogenic diabetes insipidus) characterized by amino acid exchanges at the C-terminal end of transmembrane helix TM I and TM VII. In contrast, mutants with amino acid exchanges at the interface of TM II and IV were not rescued by either antagonist. The mechanisms involved in successful rescue of cell surface delivery are explained in a three-dimensional homology model of the antagonist-bound hV2R.
Collapse
Affiliation(s)
- Stefan Wüller
- Forschungsinstitut für Molekulare Pharmakologie, Campus Berlin Buch, Robert-Roessle-Str. 10, 13125 Berlin, Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Schülein R. The early stages of the intracellular transport of membrane proteins: clinical and pharmacological implications. Rev Physiol Biochem Pharmacol 2004; 151:45-91. [PMID: 15103508 DOI: 10.1007/s10254-004-0022-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Intracellular transport mechanisms ensure that integral membrane proteins are delivered to their correct subcellular compartments. Efficient intracellular transport is a prerequisite for the establishment of both cell architecture and function. In the past decade, transport processes of proteins have also drawn the attention of clinicians and pharmacologists since many diseases have been shown to be caused by transport-deficient proteins. Membrane proteins residing within the plasma membrane are transported via the secretory (exocytotic) pathway. The general transport routes of the secretory pathway are well established. The transport of membrane proteins starts with their integration into the ER membrane. The ribosomes synthesizing membrane proteins are targeted to the ER membrane, and the nascent chains are co-translationally integrated into the bilayer, i.e., they are inserted while their synthesis is in progress. During ER insertion, the orientation (topology) of the proteins in the membrane is determined. Proteins are folded, and their folding state is checked by a quality control system that allows only correctly folded forms to leave the ER. Misfolded or incompletely folded forms are retained, transported back to the cytosol and finally subjected to proteolysis. Correctly folded proteins are transported in the membranes of vesicles through the ER/Golgi intermediate compartment (ERGIC) and the individual compartments of the Golgi apparatus ( cis, medial, trans) to the plasma membrane. In this review, the current knowledge of the first stages of the intracellular trafficking of membrane proteins will be summarized. This "early secretory pathway" includes the processes of ER insertion, topology determination, folding, quality control and the transport to the Golgi apparatus. Mutations in the genes of membrane proteins frequently lead to misfolded forms that are recognized and retained by the quality control system. Such mutations may cause inherited diseases like cystic fibrosis or retinitis pigmentosa. In the second part of this review, the clinical implications of the early secretory pathway will be discussed. Finally, new pharmacological strategies to rescue misfolded and transport-defective membrane proteins will be outlined.
Collapse
Affiliation(s)
- R Schülein
- Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany.
| |
Collapse
|
14
|
Sangkuhl K, Schulz A, Römpler H, Yun J, Wess J, Schöneberg T. Aminoglycoside-mediated rescue of a disease-causing nonsense mutation in the V2 vasopressin receptor gene in vitro and in vivo. Hum Mol Genet 2004; 13:893-903. [PMID: 14998935 DOI: 10.1093/hmg/ddh105] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Many human diseases are caused by inactivating mutations in specific G-protein-coupled receptors (GPCRs). In about 10% of these cases, a premature stop codon leads to the generation of a truncated, functionally inactive receptor protein. In this study, we tested the hypothesis that such GPCR mutations can be functionally rescued in vitro and in vivo by treatment with aminoglycoside antibiotics, which are known for their ability to suppress premature termination codons. As a model system, we studied a mutant V2 vasopressin receptor (AVPR2) containing the inactivating E242X nonsense mutation which mimics human X-linked nephrogenic diabetes insipidus (XNDI) when introduced into mice via gene targeting techniques. Studies with cultured mammalian cells expressing the E242X mutant receptor showed that G418 (geneticin) was by far the most potent aminoglycoside antibiotic capable of suppressing the E242X nonsense codon. Strikingly, G418 treatment increased AVP-mediated cAMP responses in cultured kidney collecting duct cells prepared from E242X mutant mice in vitro, and significantly improved the urine-concentrating ability of E242X mutant mice in vivo. This is the first study demonstrating that G418 (aminoglycosides) can ameliorate the clinical symptoms of a disease-causing premature stop codon in a member of the GPCR superfamily.
Collapse
MESH Headings
- Aminoglycosides/pharmacology
- Animals
- COS Cells
- Cells, Cultured
- Codon, Nonsense/drug effects
- Cricetinae
- Diabetes Insipidus, Nephrogenic/drug therapy
- Diabetes Insipidus, Nephrogenic/genetics
- Female
- Gentamicins/pharmacokinetics
- Gentamicins/pharmacology
- Humans
- Kidney Tubules, Collecting/cytology
- Kidney Tubules, Collecting/drug effects
- Kidney Tubules, Collecting/metabolism
- Mice
- Mice, Mutant Strains
- Receptors, G-Protein-Coupled/drug effects
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Vasopressin/drug effects
- Receptors, Vasopressin/genetics
- Receptors, Vasopressin/metabolism
Collapse
Affiliation(s)
- Katrin Sangkuhl
- Institute of Biochemistry, Department of Molecular Biochemistry, Medical Faculty, University of Leipzig, Leipzig, Germany
| | | | | | | | | | | |
Collapse
|
15
|
Filipek S, Teller DC, Palczewski K, Stenkamp R. The crystallographic model of rhodopsin and its use in studies of other G protein-coupled receptors. ANNUAL REVIEW OF BIOPHYSICS AND BIOMOLECULAR STRUCTURE 2003; 32:375-97. [PMID: 12574068 PMCID: PMC1351250 DOI: 10.1146/annurev.biophys.32.110601.142520] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
G protein-coupled receptors (GPCRs) are integral membrane proteins that respond to environmental signals and initiate signal transduction pathways activating cellular processes. Rhodopsin is a GPCR found in rod cells in retina where it functions as a photopigment. Its molecular structure is known from cryo-electron microscopic and X-ray crystallographic studies, and this has reshaped many structure/function questions important in vision science. In addition, this first GPCR structure has provided a structural template for studies of other GPCRs, including many known drug targets. After presenting an overview of the major structural elements of rhodopsin, recent literature covering the use of the rhodopsin structure in analyzing other GPCRs will be summarized. Use of the rhodopsin structural model to understand the structure and function of other GPCRs provides strong evidence validating the structural model.
Collapse
Affiliation(s)
- Slawomir Filipek
- Departments of Biological Structure
- Biomolecular Structure Center, University of Washington, Seattle, Washington 98195; ;;
- International Institute of Molecular and Cell Biology and
- Faculty of Chemistry, University of Warsaw, 02-109 Warsaw, Poland;
| | - David C. Teller
- Biochemistry
- Biomolecular Structure Center, University of Washington, Seattle, Washington 98195; ;;
| | | | - Ronald Stenkamp
- Departments of Biological Structure
- Biomolecular Structure Center, University of Washington, Seattle, Washington 98195; ;;
| |
Collapse
|
16
|
Grantcharova E, Furkert J, Reusch HP, Krell HW, Papsdorf G, Beyermann M, Schulein R, Rosenthal W, Oksche A. The extracellular N terminus of the endothelin B (ETB) receptor is cleaved by a metalloprotease in an agonist-dependent process. J Biol Chem 2002; 277:43933-41. [PMID: 12226103 DOI: 10.1074/jbc.m208407200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The extracellular N terminus of the endothelin B (ET(B)) receptor is susceptible to limited proteolysis (cleavage at R64 downward arrow S65), but the regulation and the functional consequences of the proteolysis remain elusive. We analyzed the ET(B) receptor or an ET(B)-GFP fusion protein stably or transiently expressed in HEK293 cells. After incubation of cells at 4 degrees C, only the full-length ET(B) receptor was detected at the cell surface. However, when cells were incubated at 37 degrees C, N-terminal cleavage was observed, provided endothelin 1 was present during the incubation. Cleavage was not inhibited by internalization inhibitors (sucrose, phenylarsine oxide). However, in cells incubated with both internalization inhibitors and metalloprotease inhibitors (batimastat, inhibitor of TNFalpha-convertase) or metal chelators (EDTA, phenanthroline), the cleavage was blocked, indicating that metalloproteases cleave the agonist-occupied ET(B) receptor at the cell surface. Functional analysis of a mutant ET(B) receptor lacking the first 64 amino acids ([Delta2-64]ET(B) receptor) revealed normal functional properties, but a 15-fold reduced cell surface expression. The results suggest a role of the N-terminal proteolysis in the regulation of cell surface expression of the ET(B) receptor. This is the first example of a multispanning membrane protein, which is cleaved by a metalloprotease, but retains its functional activity and overall structure.
Collapse
Affiliation(s)
- Evelina Grantcharova
- Forschungsinstitut für Molekulare Pharmakologie, Campus Berlin Buch, Robert-Roessle-Strasse 10, 13125 Berlin, Federal Republic of Germany
| | | | | | | | | | | | | | | | | |
Collapse
|