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Abstract
Activating and inactivating mutations in numerous human G protein-coupled receptors (GPCRs) are associated with a wide range of disease phenotypes. Here we use several class A GPCRs with a particularly large set of identified disease-associated mutations, many of which were biochemically characterized, along with known GPCR structures and current models of GPCR activation, to understand the molecular mechanisms yielding pathological phenotypes. Based on this mechanistic understanding we also propose different therapeutic approaches, both conventional, using small molecule ligands, and novel, involving gene therapy.
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Abstract
Targeted positioning of the water channel AQP2 (aquaporin-2) strictly regulates body water homoeostasis. Trafficking of AQP2 to the apical membrane is critical for the reabsorption of water in renal collecting ducts. In addition to the cAMP-mediated effect of vasopressin on AQP2 trafficking to the apical membrane, other signalling cascades can also induce this sorting. Recently, AQP2-binding proteins which could regulate this trafficking have been discovered; SPA-1 (signal-induced proliferation-associated gene-1), a GAP (GTPase-activating protein) for Rap1, and the cytoskeletal protein actin. This review summarizes recent advances related to the trafficking mechanisms of AQP2.
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Affiliation(s)
- Yumi Noda
- Department of Nephrology, Tokyo Medical and Dental University, Tokyo 113-8519, Japan
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3
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Tsutsumi Z, Inokuchi T, Tamada D, Moriwaki Y, Ka T, Takahashi S, Yamamoto T. Compound heterozygous mutation of aquaporin 2 gene in woman patient with congenital nephrogenic diabetes insipidus. Intern Med 2009; 48:437-40. [PMID: 19293543 DOI: 10.2169/internalmedicine.48.1642] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We performed mutational analyses of a woman patient with congenital nephrogenic diabetes insipidus referred to us during pregnancy. The diagnosis was made during the neonatal period, after which she was treated with spironolactone and hydrochlorothiazide. Our examination showed the patient to be apparently in good health without definite evidence of dehydration. Serum and urine osmolality were 220 mOsm/L and 50 mOsm/L, respectively, and the serum concentration of AVP was 2.7 pg/mL. Results of a water-deprivation test performed after delivery were compatible with nephrogenic diabetes insipidus. Mutational analyses showed that the patient was a compound heterozygote with point mutations at nucleotide position 298 (G to A; G100R) in exon 1 and nucleotide position 374 (C to T; T125M) in exon 2 of the aquaporin 2 gene, which have been previously described.
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Affiliation(s)
- Zenta Tsutsumi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya
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Spanakis E, Milord E, Gragnoli C. AVPR2 variants and mutations in nephrogenic diabetes insipidus: review and missense mutation significance. J Cell Physiol 2008; 217:605-17. [PMID: 18726898 DOI: 10.1002/jcp.21552] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Almost 90% of nephrogenic diabetes insipidus (NDI) is due to mutations in the arginine-vasopressin receptor 2 gene (AVPR2). We retrospectively examined all the published mutations/variants in AVPR2. We planned to perform a comprehensive review of all the AVPR2 mutations/variants and to test whether any amino acid change causing a missense mutation is significantly more or less common than others. We performed a Medline search and collected detailed information regarding all AVPR2 mutations and variants. We performed a frequency comparison between mutated and wild-type amino acids and codons. We predicted the mutation effect or reported it based on published in vitro studies. We also reported the ethnicity of each mutation/variant carrier. In summary, we identified 211 AVPR2 mutations which cause NDI in 326 families and 21 variants which do not cause NDI in 71 NDI families. We described 15 different types of mutations including missense, frameshift, inframe deletion, deletion, insertion, nonsense, duplication, splicing and combined mutations. The missense mutations represent the 55.83% of all the NDI published families. Arginine and tyrosine are significantly (P = 4.07E-08 and P = 3.27E-04, respectively) the AVPR2 most commonly mutated amino acids. Alanine and glutamate are significantly (P = 0.009 and P = 0.019, respectively) the least mutated AVPR2 amino acids. The spectrum of mutations varies from rare gene variants or polymorphisms not causing NDI to rare mutations causing NDI, among which arginine and tyrosine are the most common missense. The AVPR2 mutations are spread world-wide. Our study may serve as an updated review, comprehensive of all AVPR2 variants and specific gene locations. J. Cell. Physiol. 217: 605-617, 2008. (c) 2008 Wiley-Liss, Inc.
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Affiliation(s)
- Elias Spanakis
- Laboratory of Molecular Genetics of Complex and Monogenic Disorders, Department of Medicine and Cellular & Molecular Physiology, M. S. Hershey Medical Center, Hershey, Pennsylvania 17033, USA
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Robben JH, Knoers NVAM, Deen PMT. Cell biological aspects of the vasopressin type-2 receptor and aquaporin 2 water channel in nephrogenic diabetes insipidus. Am J Physiol Renal Physiol 2006; 291:F257-70. [PMID: 16825342 DOI: 10.1152/ajprenal.00491.2005] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
In the renal collecting duct, water reabsorption is regulated by the antidiuretic hormone vasopressin (AVP). Binding of this hormone to the vasopressin V2 receptor (V2R) leads to insertion of aquaporin-2 (AQP2) water channels in the apical membrane, thereby allowing water reabsorption from the pro-urine to the interstitium. The disorder nephrogenic diabetes insipidus (NDI) is characterized by the kidney's inability to concentrate pro-urine in response to AVP, which is mostly acquired due to electrolyte disturbances or lithium therapy. Alternatively, NDI is inherited in an X-linked or autosomal fashion due to mutations in the genes encoding V2R or AQP2, respectively. This review describes the current knowledge of the cell biological causes of NDI and how these defects may explain the patients' phenotypes. Also, the increased understanding of these cellular defects in NDI has opened exciting initiatives in the development of novel therapies for NDI, which are extensively discussed in this review.
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MESH Headings
- Amino Acid Sequence
- Aquaporin 2/genetics
- Aquaporin 2/physiology
- DNA/genetics
- Diabetes Insipidus, Nephrogenic/etiology
- Diabetes Insipidus, Nephrogenic/genetics
- Diabetes Insipidus, Nephrogenic/physiopathology
- Diabetes Insipidus, Nephrogenic/therapy
- Gene Expression Regulation/physiology
- Genetic Diseases, X-Linked/etiology
- Genetic Diseases, X-Linked/genetics
- Genetic Diseases, X-Linked/physiopathology
- Genetic Diseases, X-Linked/therapy
- Humans
- Molecular Sequence Data
- Mutation/genetics
- Mutation/physiology
- Receptors, Vasopressin/genetics
- Receptors, Vasopressin/physiology
- Vasopressins/physiology
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Affiliation(s)
- Joris H Robben
- Department of Physiology, Nijmegen Centre for Molecular Life Sciences and Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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Noda Y, Sasaki S. Regulation of aquaporin-2 trafficking and its binding protein complex. Biochim Biophys Acta 2006; 1758:1117-25. [PMID: 16624255 DOI: 10.1016/j.bbamem.2006.03.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Revised: 02/14/2006] [Accepted: 03/07/2006] [Indexed: 12/19/2022]
Abstract
Trafficking of water channel aquaporin-2 (AQP2) to the apical membrane is critical to water reabsorption in renal collecting ducts and its regulation maintains body water homeostasis. However, exact molecular mechanisms which recruit AQP2 are unknown. Recent studies highlighted a key role for spatial and temporal regulation of actin dynamics in AQP2 trafficking. We have recently identified AQP2-binding proteins which directly regulate this trafficking: SPA-1, a GTPase-activating protein (GAP) for Rap1, and cytoskeletal protein actin. In addition, a multiprotein "force generator" complex which directly binds to AQP2 has been discovered. This review summarizes recent advances related to the mechanism for AQP2 trafficking.
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Affiliation(s)
- Yumi Noda
- Department of Nephrology, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Tokyo 113-8519, Japan.
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Noda Y, Sasaki S. Molecular Mechanisms and Drug Development in Aquaporin Water Channel Diseases: Molecular Mechanism of Water Channel Aquaporin-2 Trafficking. J Pharmacol Sci 2004; 96:249-54. [PMID: 15539762 DOI: 10.1254/jphs.fmj04004x2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Targeted positioning of water channel aquaporin-2 (AQP2) strictly regulates body water homeostasis. Trafficking of AQP2 to the apical membrane is critical for the reabsorption of water in renal collecting ducts. Besides the cAMP-mediated effect of vasopressin on AQP2 trafficking to the apical membrane, other signaling cascades also induce this sorting. Recently, AQP2-binding proteins that directly regulate this trafficking have been uncovered: SPA-1, a GTPase-activating protein (GAP) for Rap1, and cytoskeletal protein actin. This review summarizes recent advances related to the trafficking mechanism of AQP2 and its defect causing nephrogenic diabetes insipidus (NDI).
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Affiliation(s)
- Yumi Noda
- Department of Nephrology, Graduate School, Tokyo Medical and Dental University, Japan.
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Abstract
A manutenção da constância da osmolalidade plasmática e do equilíbrio hidroeletrolítico deve-se à regulação do volume extracelular e da natremia, através da integração entre as ações do hormônio antidiurético (ADH), o sistema renina-angiotensina-aldosterona (SRAA) e o mecanismo da sede. Distúrbios na síntese, secreção ou ação do ADH podem resultar em síndromes poliúricas, em que ocorre excreção aumentada de urina hipotônica, resultante da ingestão excessiva de água, secreção ou ação inadequadas do ADH ou alterações nos canais de água da aquaporina-2 (AQP2). A hiponatremia pode ocorrer por depleção de sal, mecanismos dilucionais ou metabólicos, além de ser uma freqüente ocorrência após a cirurgia hipofisária, tendo sido descrita em 9 a 35% de pacientes operados. A causa pode ser devida a uma lesão transitória ou definitiva da hipófise posterior, a síndrome de secreção inapropriada do hormônio antidiurético (SIADH) ou, mais freqüentemente, a síndrome cerebral perdedora de sal (SCPS). A apresentação clínica de ambas as síndromes é similar e o diagnóstico diferencial pode apresentar dificuldades. A determinação do estado volêmico é essencial para o diagnóstico, já que os pacientes portadores de SIADH caracterizam-se por serem euvolêmicos ou hipervolêmicos, enquanto aqueles com a SCPS são hipovolêmicos. Os critérios para o diagnóstico incluem parâmetros clínicos, determinação da osmolalidade plasmática e urinária e os testes de restrição hídrica, sobrecarga hipertônica e o da furosemida, importante na discriminação entre SIADH e SCPS. O tratamento das síndromes poliúricas depende da etiologia e inclui o uso de análogos do ADH, diuréticos, ou outras drogas tais como clorpropramida, clofibrato, corticóides e carbamazepina. O tratamento da SIADH necessita de restrição de líqüidos e/ou furosemida para diminuir o volume de água extracelular. O tratamento da SCPS, ao contrário, implica em reposição de volume com fornecimento de suplementação de sódio e líqüidos, sendo que a fludrocortisona pode ser uma boa alternativa terapêutica.
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Abstract
A maioria dos hormônios polipeptídicos e mesmo o cálcio extracelular atuam em suas células-alvo através de receptores acoplados à proteína G (GPCRs). Nos últimos anos, tem sido freqüente a identificação e associação causal de mutações em proteínas G e em GPCRs com diversas endocrinopatias, como diabetes insipidus nefrogênico, hipotiroidismo familiar, puberdade precoce familiar no sexo masculino e nódulos tiroidianos hiperfuncionantes. Nesta revisão, abordamos aspectos referentes ao mecanismo de transdução do sinal acoplado à proteína G, e descrevemos como mutações em GPCRs podem levar a algumas doenças endócrinas. Finalmente, comentamos a respeito das implicações diagnósticas e terapêuticas associadas com o maior conhecimento dos GPCRs.
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Affiliation(s)
- F Gilbert
- Weill Medical College of Cornell University, New York, NY 10021, USA.
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Arthus MF, Lonergan M, Crumley MJ, Naumova AK, Morin D, DE Marco LA, Kaplan BS, Robertson GL, Sasaki S, Morgan K, Bichet DG, Fujiwara TM. Report of 33 novel AVPR2 mutations and analysis of 117 families with X-linked nephrogenic diabetes insipidus. J Am Soc Nephrol 2000; 11:1044-1054. [PMID: 10820168 DOI: 10.1681/asn.v1161044] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
X-linked nephrogenic diabetes insipidus (NDI) is a rare disease caused by mutations in the arginine vasopressin receptor 2 gene (AVPR2). Thirty-three novel AVPR2 mutations were identified in 62 families that were not included in our previous studies. This study describes the diversity of mutations observed in a total of 117 families, the number of affected people at the time of diagnosis, skewed X chromosome inactivation in severely affected females, the inferred parental origin of de novo mutations, and it provides estimates of incidence. Among 117 families, there were 82 different putative disease-causing mutations. Based on haplotype analysis, it can be inferred that when the same AVPR2 mutation is identified in different families that were not known to be related, the mutations most likely arose independently. More than half of the families had only one affected male; two families presented with a severely affected female and no family history of NDI. A de novo mutation arose during oogenesis in the mother in 20% of isolated cases. The estimate of about 8.8 per million male live births of the incidence of X-linked NDI in the province of Quebec, Canada may be representative of the general population except in Nova Scotia and New Brunswick, where the incidence is more than six times higher. Documentation of the diversity of mutations will assist in revealing the full spectrum of clinical variation. Discussion of genetic and population genetic aspects of X-linked NDI may contribute to early diagnosis and treatment.
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Affiliation(s)
- Marie-Françoise Arthus
- Department of Medicine, Université de Montréal and Research Centre, Hôpital du Sacré-Coeur de Montréal, Montreal, Canada
| | - Michèle Lonergan
- Department of Medicine, Université de Montréal and Research Centre, Hôpital du Sacré-Coeur de Montréal, Montreal, Canada
| | - M Joyce Crumley
- Montreal General Hospital Research Institute, Montreal, Canada
| | - Anna K Naumova
- Department of Medicine, McGill University, Montreal, Canada
- Department of Obstetrics and Gynecology, McGill University, Montreal, Canada
| | - Denis Morin
- Unité 469, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique-INSERM de Pharmacologie-Endocrinologie, Montpellier, France
| | - Luiz A DE Marco
- Department of Pharmacology, University Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Bernard S Kaplan
- Division of Nephrology, The Children's Hospital of Philadelphia and Department of Pediatrics, The University of Pennsylvania, Philadelphia, Pennsylvania
| | - Gary L Robertson
- Clinical Research Center and Northwestern University Medical School, Chicago, Illinois
| | - Sei Sasaki
- Second Department of Internal Medicine, School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kenneth Morgan
- Department of Human Genetics, McGill University, Montreal, Canada
- Department of Medicine, McGill University, Montreal, Canada
- Montreal General Hospital Research Institute, Montreal, Canada
| | - Daniel G Bichet
- Department of Medicine, Université de Montréal and Research Centre, Hôpital du Sacré-Coeur de Montréal, Montreal, Canada
| | - T Mary Fujiwara
- Department of Human Genetics, McGill University, Montreal, Canada
- Department of Medicine, McGill University, Montreal, Canada
- Montreal General Hospital Research Institute, Montreal, Canada
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