Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01185 (vasopressin)
 23,126 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We analyzed an X-linked metallothionein-vasopressin (MTVP) fusion transgene that undergoes X-chromosome inactivation (X inactivation) and an X-linked transferrin (TFN) transgene that escapes X inactivation with respect to methylation in the 5' regulatory regions. The MTVP transgene promoter region is unmethylated when the transgene is on the active X chromosome and methylated when on the inactive X chromosome. Interestingly, the MTVP transgene is not detectably transcribed from the male X chromosome, although it is unmethylated, consistent with its availability for transcription. The TFN transgene promoter region is hypomethylated on both the active and inactive X chromosomes, consistent with its expression from both chromosomes. The TFN and MTVP transgenes have been mapped to chromosomal regions D and C, respectively, by fluorescence in situ hybridization. These observations are discussed in the context of our understanding of the role of DNA methylation in the spread and maintenance of X-chromosome inactivation.
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PMID:Comparative methylation analysis of murine transgenes that undergo or escape X-chromosome inactivation. 987 69

The molecular mechanisms governing the G protein coupling selectivity of different members of the vasopressin receptor family were studied by using a combined molecular genetic/biochemical approach. While the V1a and V1b vasopressin receptors are selectively linked to G proteins of the Gq/11 class, the V2 vasopressin receptor is preferentially coupled to Gs. Systematic functional analysis of V1a/V2 hybrid receptors showed that the second intracellular loop of the V1a receptor is required and sufficient for efficient coupling to Gq/11, whereas the third intracellular loop of the V2 receptor is required and sufficient for coupling to Gs. By using a strategy involving the coexpression of the wild type V1a receptor with chimeric G protein alpha s/alpha q subunits, two C-terminal alpha q/11 residues were identified that are critical for proper receptor recognition. We previously demonstrated -in transiently transfected COS-7 cells- that selected mutant V2 vasopressin receptors (all of which have been identified in X-linked nephrogenic diabetes insipidus patients) containing inactivating mutations in the C-terminal third of the receptor protein (including missense, frameshift, or nonsense mutations) can be functionally rescued by coexpression with a C-terminal V2 receptor fragment (V2-tail) spanning the region where the various mutations occur. Co-immunoprecipitation experiments and a newly developed sandwich ELISA revealed that the V2-tail polypeptide directly interacts with the mutant V2 receptors thus creating a functional receptor protein. To study the potential therapeutic usefulness of these findings, CHO cell lines stably expressing low levels of functionally inactive mutant V2 vasopressin receptors (E242stop, Y280C, and W284stop) were created and infected with a recombinant adenovirus coding for the V2-tail polypeptide. Following adenovirus infection, arginine vasopressin (AVP) gained the ability to stimulate cAMP formation in all CHO cell clones studied. Adenovirus-mediated gene transfer also proved to be a highly efficient method to achieve expression of the V2-tail fragment (as well as of the wild type V2 vasopressin receptor) in MDCK renal tubular cells. We therefore speculate that the targeted expression of receptor fragments in vivo may represent a novel strategy in the treatment of human diseases caused by inactivating mutations in distinct G protein-coupled receptors.
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PMID:Molecular aspects of vasopressin receptor function. 1002 24

The function of small GTPases is fine-tuned by a complex network of regulatory proteins such as GTPase-activating proteins. The C1 gene at Xq28 encodes a protein assumed to function as a Rho GTPase-activating protein (rhoGAP). Characterization of the molecular defect causing X-linked nephrogenic diabetes insipidus (NDI) in a patient revealed a submicroscopic deletion of a 21.5-kb genomic fragment encompassing the entire arginine-vasopressin V2 receptor gene (AVPR2) and most of the C1 gene locus. In the absence of detailed information about the physiological relevance and specific functions of rhoGAP C1, a thorough clinical and laboratory investigation of the patient was performed. Besides clearly defined NDI symptoms caused by deletion of the AVPR2 gene, no major morphological abnormalities as determined by physical examination, radiography, ultrasound, and computed tomographic scan were detected. Extensive analysis of blood chemical, enzyme, and hormone values over a period of 16 years showed no deviations from normal ranges. On the basis of our observations, the rhoGAP C1 protein is not essential for normal development in the human. Because of a predominant expression pattern of the C1 gene in hematopoietic cells, we focused on immunologic and hematologic laboratory parameters of the affected boy and the mother who was found to be heterozygous. Differential white cell counts, including lymphocyte typing, determination of lymphokines, cytokines, and immunoglobulins, as well as numerous leukocyte function tests, showed no pathological findings. Therefore, we postulate that the loss of rhoGAP C1 function is most likely compensated by other members of the GAP family.
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PMID:Compound deletion of the rhoGAP C1 and V2 vasopressin receptor genes in a patient with nephrogenic diabetes insipidus. 1042 39

The G protein-coupled vasopressin V2 receptor (V2 receptor) contains a pair of conserved cysteine residues (C112 and C192) which are thought to form a disulfide bond between the first and second extracellular loops. The conserved cysteine residues were found to be important for the correct formation of the ligand binding domain of some G protein-coupled receptors. Here we have assessed the properties of the V2 receptor after site-directed mutagenesis of its conserved cysteine residues in transiently transfected human embryonic kidney (HEK 293) cells. Mutant receptors (C112S, C112A and C192S, C192A) were non-functional and located mostly in the cell's interior. The conserved cysteine residues of the V2 receptor are thus not only important for the structure of the ligand binding domain but also for efficient intracellular receptor transport. In addition to the functional significance of the conserved cysteine residues, we have also analyzed the defects of two mutant V2 receptors which cause X-linked nephrogenic diabetes insipidus (NDI) by the introduction of additional cysteine residues into the second extracellular loop (mutants G185C, R202C). These mutations are assumed to impair normal disulfide bond formation. Mutant receptor G185C and R202C were efficiently transported to the plasma membrane but were defective in ligand binding. Only in the case of the mutant receptor R202C, the more sensitive adenylyl cyclase activity assay revealed vasopressin-stimulated cAMP formation with a 35-fold increased EC(50) value and with a reduced EC(max), indicating that ligand binding is not completely abolished. Taking the unaffected intracellular transport of both NDI-causing mutant receptors into account, our results indicate that the observed impairment of ligand binding by the additional cysteine residues is not due to the prevention of disulfide bond formation between the conserved cysteine residues.
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PMID:The role of conserved extracellular cysteine residues in vasopressin V2 receptor function and properties of two naturally occurring mutant receptors with additional extracellular cysteine residues. 1064 21

The aim of this study was to identify loss-of-function mutations of the V2 vasopressin receptor gene (AVPR2) in Italian patients affected by X-linked nephrogenic diabetes insipidus (NDI). Mutations were found in 15 of the 18 unrelated families investigated: nine of these mutations were previously unknown, including two affecting residues located in regions known to be important for determining the pharmacologic properties of the receptor, which were therefore functionally investigated. The first (A84D) involves a residue located near an aspartic acid (D85) that is highly conserved in all G protein-coupled receptors and that is believed to play a role in the process of their isomerization into functionally active and inactive states. The present study indicates that this mutation not only affects receptor folding in such a way as to lead to its retention inside the intracellular compartments but, as expected, also has profound effects on its binding and coupling properties. The second was a mutation of a tryptophan located at the beginning of the first extracellular loop (W99R) that greatly impaired the binding properties of the receptor and had a minor effect on its intracellular routing. Molecular analysis of the first extracellular loop bearing this mutation suggests that this residue plays a fundamental role in stabilizing the peptide/receptor interactions responsible for the high-affinity binding of agonists to the V2 receptor.
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PMID:Nephrogenic diabetes insipidus: functional analysis of new AVPR2 mutations identified in Italian families. 1082 Jan 67

Hereditary non-X-linked nephrogenic diabetes insipidus (NDI) is caused by mutations in the aquaporin-2 (AQP2) water channel. In transfected cells, the human disease-causing mutant AQP2-T126M is retained at the endoplasmic reticulum (ER) where it is functional and targetable to the plasma membrane with chemical chaperones. A mouse knock-in model of NDI was generated by targeted gene replacement using a Cre-loxP strategy. Along with T126M, mutations H122S, N124S, and A125T were introduced to preserve the consensus sequence for N-linked glycosylation found in human AQP2. Breeding of heterozygous mice yielded the expected Mendelian distribution with 26 homozygous mutant offspring of 99 live births. The mutant mice appeared normal at 2-3 days after birth but failed to thrive and generally died by day 6 if not given supplemental fluid. Urine/serum analysis showed a urinary concentrating defect with serum hyperosmolality and low urine osmolality that was not increased by a V2 vasopressin agonist. Northern blot analysis showed up-regulated AQP2-T126M transcripts of identical size to wild-type AQP2. Immunoblots showed complex glycosylation of wild-type AQP2 but mainly endoglycosidase H-sensitive core glycosylation of AQP2-T126M indicating ER-retention. Biochemical analysis revealed that the AQP2-T126M protein was resistant to detergent solubilization. Kidneys from mutant mice showed collecting duct dilatation, papillary atrophy, and unexpectedly, some plasma membrane AQP2 staining. The severe phenotype of the AQP2 mutant mice compared with that of mice lacking kidney water channels AQP1, AQP3, and AQP4 indicates a critical role for AQP2 in neonatal renal function in mice. Our results establish a mouse model of human autosomal NDI and provide the first in vivo biochemical data on a disease-causing AQP2 mutant.
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PMID:Neonatal mortality in an aquaporin-2 knock-in mouse model of recessive nephrogenic diabetes insipidus. 1103 38

The V2 vasopressin receptor (V2R) plays a key role in the maintenance of a normal body water balance. To generate an in vivo model that allows the physiological and molecular analysis of the role of V2Rs in kidney function, we have created mouse lines that lack functional V2Rs by using targeted mutagenesis in mouse embryonic stem cells. Specifically, we introduced a nonsense mutation known to cause X-linked nephrogenic diabetes insipidus (XNDI) in humans (Glu242stop) into the mouse genome. V2R-deficient hemizygous male pups showed a decrease in basal urine osmolalities and were unable to concentrate their urine. These pups also exhibited an enlargement of renal pelvic space, failed to thrive, and died within the first week after birth due to hypernatremic dehydration. Interestingly, female mice heterozygous for the V2R mutation showed normal growth but displayed an XNDI-like phenotype, characterized by reduced urine concentrating ability of the kidney, polyuria, and polydipsia. Western blot analysis and immunoelectron microscopic studies showed that the loss of functional V2Rs had no significant effect on the basal expression levels of aquaporin-2 and the bumetanide-sensitive Na-K-2Cl cotransporter (BSC-1). The V2R mutant mice described here should serve as highly useful tools for the development of novel therapeutic strategies for the treatment of XNDI.
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PMID:Generation and phenotype of mice harboring a nonsense mutation in the V2 vasopressin receptor gene. 1110 89

Contractions of rat thoracic aorta to vasopressin (VP) are threefold higher in females (F) than in males (M), primarily because nitric oxide (NO) attenuation of contraction is greater in M. To determine the role of the androgen receptor (AR) in this mechanism, vascular reactivity to VP was examined in thoracic aorta of the testicular-feminized male (Tfm) rat, which has an X-linked, recessive defect in AR function in affected M. Maximal contraction of normal aortas to VP was fourfold higher in F (4,128 +/- 291 mg/mg ring wt) than in M (971 +/- 133 mg); maximal response of Tfm (3,967 +/- 253 mg) was similar to that of normal F. N(G)-nitro-L-arginine methyl ester increased maximal response to VP threefold in M but had no effect in F or Tfm. In contrast, maximal contraction of normal aortas to phenylephrine was 43% higher in M (4,011 +/- 179 mg) than in F (2,809 +/- 78 mg); maximal response of Tfm (2,716 +/- 126 mg) was similar to that of normal F. N(G)-nitro-L-arginine methyl ester increased maximal response to phenylephrine by >50% in F and Tfm but had no effect in M. Maximal contractile response to 80 mM KCl did not differ among M, F, or Tfm. Thus androgens and normal vascular AR function are important in the greater NO-mediated attenuation of reactivity to VP in M than in F rat aorta, which may involve specific modulation of endothelial VP signal transduction pathways and NO release by androgens. These data also establish the importance of the Tfm rat as a model to study the effects of androgens on cardiovascular function.
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PMID:Androgen-receptor defect abolishes sex differences in nitric oxide and reactivity to vasopressin in rat aorta. 1171 25

The identification of the different molecular causes of congenital nephrogenic diabetes insipidus (NDI), a disorder characterized by renal insensitivity to the antidiuretic effect of arginine vasopressin, has been of indispensable importance for understanding the cellular processes involved in diuresis and antidiuresis. In most cases, NDI is X-linked and caused by mutations in the vasopressin type-2 receptor (V2R) gene. Mutations in the aquaporin-2 (AQP2) water channel gene are responsible for the autosomal recessive and rare dominant forms of NDI. By in vitro expression, it has been shown that the majority of V2R mutants and all AQP2 mutants found in recessive NDI are misfolded and retained within the endoplasmic reticulum (ER). Functional analysis of one of the mutations identified in dominant NDI showed that this mutant is properly folded and transported out of the ER, but is retained in the Golgi region. In addition, this mutant, in contrast to mutants found in recessive NDI, is able to heterotetramerize with wild-type AQP2. The resulting complex is hindered in its transport to the membrane, a finding that explains the dominant-negative effect of this mutation. Several new methodologies focused on the molecular defects causing NDI are presently being investigated in vitro and might eventually develop into useful therapeutic strategies.
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PMID:Molecular and cellular defects in nephrogenic diabetes insipidus. 1179 19

By screening patients with X-linked nephrogenic diabetes insipidus (NDI) for mutations within the V(2) vasopressin receptor (AVPR2) gene, we have identified six novel and two recurrent mutations. Additionally, one patient revealed a genomic deletion of 3.2 kb encompassing most of the AVPR2 gene and the last exon/3'-region of C1 gene, which is in close proximity to the AVPR2 locus. In-depth characterization of the mutant AVPR2s by a combination of functional and immunological techniques allowed to gain further insight into molecular mechanisms leading to the receptor dysfunction. Aiming at the functional reconstitution of mutant G protein-coupled receptors, several strategies of potential therapeutic usefulness have been tested. Because the functional rescue of truncated receptors is most challenging, we addressed this issue by applying an aminoglycoside approach. Here, we demonstrate that the misreading capacity of the aminoglycoside antibiotic geneticin was sufficient to restore function of mutant AVPR2s harboring premature stop codons in an in vitro expression system.
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PMID:Aminoglycoside pretreatment partially restores the function of truncated V(2) vasopressin receptors found in patients with nephrogenic diabetes insipidus. 1241 99


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