Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Aquaporin 2 (AQP2) is responsible for regulating the concentration of urine in the collecting tubules of the kidney under the control of vasopressin (Vp). Studies using Vp-deficient Brattleboro rats, however, indicated the existence of substantial Vp-independent mechanisms for membrane insertion, as well as transcriptional regulation, of this water channel. The Vp-independent mechanism(s) is clinically relevant to patients with X-linked nephrogenic diabetes insipidus (NDI) by therapeutically bypassing the dysfunctional Vp receptor. On the basis of studies with secretin receptor-null (SCTR(-/-)) mice, we report here for the first time that mutation of the SCTR gene could lead to mild polydipsia and polyuria. Additionally, SCTR(-/-) mice were shown to have reduced renal expression of AQP2 and AQP4, as well as altered glomerular and tubular morphology, suggesting possible disturbances in the filtration and/or water reabsorption process in these animals. By using SCTR(-/-) mice as controls and comparing them with wild-type animals, we performed both in vivo and in vitro studies that demonstrated a role for secretin in stimulating (i) AQP2 translocation from intracellular vesicles to the plasma membrane in renal medullary tubules and (ii) expression of this water channel under hyperosmotic conditions. The present study therefore provides information for at least one of the Vp-independent mechanisms that modulate the process of renal water reabsorption. Future investigations in this direction should be important in developing therapeutic means for treating NDI patients.
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PMID:Phenotypes developed in secretin receptor-null mice indicated a role for secretin in regulating renal water reabsorption. 1728 64

The antidiuretic hormone arginine-vasopressin regulates water homeostasis in the human body by binding to its vasopressin type 2 receptor (V2R). Mutations in AVPR2, the gene encoding V2R, lead to the X-linked congenital form of nephrogenic diabetes insipidus (NDI), a disease characterized by the inability to concentrate urine in response to vasopressin; often this involves missense mutations or deletion of one or a few amino acids. In vitro V2R expression studies revealed that the function of most of these receptors is not disturbed, but due to their misfolding, the quality control mechanism of the endoplasmic reticulum (ER) retains these receptors inside the cell, thereby preventing their functioning at the plasma membrane. This review summarizes our current knowledge on ER retention of V2R mutants, and describes the different approaches that have been undertaken to restore the plasma membrane expression and function of V2R mutants in NDI in vitro and in vivo. The use of cell permeable receptor ligands (called 'pharmacological chaperones') appears promising for the treatment of NDI in a subset of patients.
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PMID:Pharmacological chaperones in nephrogenic diabetes insipidus: possibilities for clinical application. 1751 11

The endoplasmic reticulum-associated degradation (ERAD), the main quality control pathway of the cell, is crucial for the elimination of unfolded or misfolded proteins. Several diseases are associated with the retention of misfolded proteins in the early secretory pathway. Among them is X-linked nephrogenic diabetes insipidus, caused by mutations in the gene encoding the V2 vasopressin receptor (V2R). We studied the degradation pathways of three intracellularly retained V2R mutants with different misfolded domains in human embryonic kidney 293 cells. At steady state, the wild-type V2R and the complex-glycosylated mutant G201D were partially located in lysosomes, whereas core-glycosylated mutants L62P and V226E were excluded from this compartment. In pulse-chase experiments, proteasomal inhibition stabilized the nonglycosylated and core-glycosylated forms of all studied receptors. In addition, all mutants and the wild-type receptor were found to be polyubiquitinylated. Nonglycosylated and core-glycosylated receptor forms were located in cytosolic and membrane fractions, respectively, confirming the deglycosylation and retrotranslocation of ERAD substrates to the cytosol. Distinct Derlin-1-dependent and -independent ERAD pathways have been proposed for proteins with different misfolded domains (cytosolic, extracellular, and membrane) in yeast. Here, we show for the first time that V2R mutants with different misfolded domains are able to coprecipitate the ERAD components p97/valosin-containing protein, Derlin-1 and the 26S proteasome regulatory subunit 7. Our results demonstrate the presence of a Derlin-1-mediated ERAD pathway degrading wild-type and disease-causing V2R mutants with different misfolded domains in a mammalian system.
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PMID:Derlin-1 and p97/valosin-containing protein mediate the endoplasmic reticulum-associated degradation of human V2 vasopressin receptors. 1804 2

The purpose of this review is first to describe the importance of early detection of vasopressin receptor mutations responsible for X-linked nephrogenic diabetes insipidus (NDI). We have proposed that all families with hereditary diabetes insipidus should have their molecular defect identified because early diagnosis and treatment of affected infants can avert the physical and mental retardation that results from repeated episodes of dehydration. Secondly, 95 published missense mutations responsible for X-linked NDI are likely to result in misfolded arginine-vasopressin V(2) receptors that are trapped in the endoplasmic reticulum. These misfolded receptors are unable to reach the plasma membrane in principal collecting duct cells and to engage the circulating antidiuretic hormone, arginine-vasopressin. These misfolded proteins potentially could be rescued with pharmacologic chaperones, an active area of research pertinent to other hereditary protein misfolding diseases such as cystic fibrosis, phenylketonuria, and Anderson-Fabry disease among many others. Finally, a long-term careful surveillance of all patients with hereditary NDI should be performed to prevent chronic renal failure likely caused by the long-term functional tract obstruction with reflux.
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PMID:Vasopressin receptor mutations in nephrogenic diabetes insipidus. 1851 85

We report on an infant boy with congenital hydrocephalus due to L1 syndrome and polyuria due to diabetes insipidus. We initially believed his excessive urine loss was from central diabetes insipidus and that the cerebral malformation caused a secondary insufficient pituitary vasopressin release. However, he failed to respond to treatment with a vasopressin analogue, which pointed to nephrogenic diabetes insipidus (NDI). L1 syndrome and X-linked NDI are distinct clinical disorders caused by mutations in the L1CAM and AVPR2 genes, respectively, located in adjacent positions in Xq28. In this boy we found a deletion of 61,577 basepairs encompassing the entire L1CAM and AVPR2 genes and extending into intron 7 of the ARHGAP4 gene. To our knowledge this is the first description of a patient with a deletion of these three genes. He is the second patient to be described with L1 syndrome and NDI. During follow-up he manifested complications from the hydrocephalus and NDI including global developmental delay and growth failure with low IGF-1 and hypothyroidism.
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PMID:Nephrogenic diabetes insipidus in a patient with L1 syndrome: a new report of a contiguous gene deletion syndrome including L1CAM and AVPR2. 1855 46

Polyuria, hypernatremia, and hypovolemia are the major clinical signs of inherited nephrogenic diabetes insipidus (NDI). Hypernatremia is commonly considered a secondary sign caused by the net loss of water due to insufficient insertion of aquaporin-2 water channels into the apical membrane of the collecting duct cells. In the present study, we employed transcriptome-wide expression analysis to study gene expression in V2 vasopressin receptor (Avpr2)-deficient mice, an animal model for X-linked NDI. Gene expression changes in NDI mice indicate increased proximal tubular sodium reabsorption. Expression of several key genes including Na+-K+-ATPase and carbonic anhydrases was increased at the mRNA levels and accompanied by enhanced enzyme activities. In addition, altered expression was also observed for components of the eicosanoid and thyroid hormone pathways, including cyclooxygenases and deiodinases, in both kidney and hypothalamus. These effects are likely to contribute to the clinical NDI phenotype. Finally, our data highlight the involvement of the renin-angiotensin-aldosterone system in NDI pathophysiology and provide clues to explain the effectiveness of diuretics and indomethacin in the treatment of NDI.
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PMID:V2 vasopressin receptor deficiency causes changes in expression and function of renal and hypothalamic components involved in electrolyte and water homeostasis. 1871 41

X-linked lissencephaly with abnormal genitalia (XLAG) is characterized by lissencephaly, absent corpus callosum and ambiguous genitalia. We examined hypothalamic dysfunctions in a XLAG case with a novel mutation of the ARX gene, and performed immunohistochemical evaluation of the diencephalons in autopsy brain. A 1-year-old boy showed intractable epilepsy, persistent diarrhea and disturbed temperature regulation. This case had abnormalities in circadian rhythms and pituitary hormone reserve test. He died of pneumonia. The globus pallidus and subthalamic nucleus was not identified, and the putamen and thalamus were dysplasic. The suprachiasmatic nucleus was absent. A few neurons immunoreactive for vasopressin seemed to form the ectopic supraoptic-like nucleus. The diencephalons were disturbed differently in each sub-region, and the changes may be related to various hypothalamic dysfunctions.
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PMID:Analysis of the hypothalamus in a case of X-linked lissencephaly with abnormal genitalia (XLAG). 1884 66

X-linked nephrogenic diabetes insipidus (XNDI) is a severe kidney disease caused by inactivating mutations in the V2 vasopressin receptor (V2R) gene that result in the loss of renal urine-concentrating ability. At present,no specific pharmacological therapy has been developed for XNDI, primarily due to the lack of suitable animal models. To develop what we believe to be the first viable animal model of XNDI, we generated mice in which the V2R gene could be conditionally deleted during adulthood by administration of 4-OH-tamoxifen.Radioligand-binding studies confirmed the lack of V2R-binding sites in kidneys following 4-OH-tamoxifen treatment, and further analysis indicated that upon V2R deletion, adult mice displayed all characteristic symptoms of XNDI, including polyuria, polydipsia, and resistance to the antidiuretic actions of vasopressin. Gene expression analysis suggested that activation of renal EP4 PGE2 receptors might compensate for the lack of renal V2R activity in XNDI mice. Strikingly, both acute and chronic treatment of the mutant mice with a selective EP4 receptor agonist greatly reduced all major manifestations of XNDI, including changes in renal morphology.These physiological improvements were most likely due to a direct action on EP4 receptors expressed on collecting duct cells. These findings illustrate the usefulness of the newly generated V2R mutant mice for elucidating and testing new strategies for the potential treatment of humans with XNDI.
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PMID:A selective EP4 PGE2 receptor agonist alleviates disease in a new mouse model of X-linked nephrogenic diabetes insipidus. 1972 36

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.
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PMID:Diverse vasopressin V2 receptor functionality underlying partial congenital nephrogenic diabetes insipidus. 1981 97

We report a familial case of the nephrogenic syndrome of inappropriate antidiuresis (NSIAD), including 30-year followup data on two patients. The proband and one maternal uncle presented in their infancy with severe recurrent hyponatremia, and clinical pictures consistent with the syndrome of inappropriate antidiuretic hormone (SIADH) in the absence of an elevated ADH level. They were both confirmed to be hemizygous for the R137C mutation on the V2R gene (AVPR2), the same locus of the gain of function mutation demonstrated in the original reports of this condition. The proband's mother was identified as an asymptomatic carrier of this X-linked condition. Our case describes a favourable long-term outcome for NSIAD, in particular, successful treatment with oral urea during the infancy period, and with self-regulated precautions on fluid intake into adult life.
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PMID:Long-term outcomes in a family with nephrogenic syndrome of inappropriate antidiuresis. 2014 77


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