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)

To examine whether expression and distribution of aquaporin of collecting duct (AQP-CD) are regulated by vasopressin V2 receptor (V2R), we performed immunohistochemical studies with specific antibody against AQP-CD. Normal Wistar rats were divided into four groups and treated for 3 d; control, dehydration, vasopressin V1 receptor (V1R) antagonist (OPC-21268 120 mg/kg), V2R antagonist (OPC-31260 30 mg/kg). At time of death, urine osmolality (Uosm) in the dehydration group (1884 +/- 245 mOsm/kg) was significantly higher than that in the control (938 +/- 91). In the V2R antagonist group, Uosm was significantly decreased to 249 +/- 29, whereas V1R antagonist showed no effect on Uosm. In the control and V1R antagonist groups, immunofluorescence studies showed the AQP-CD staining of both apical membrane and subapical cytoplasm of CD cells of the cortex and the inner medulla. Dehydration increased the immunostaining of both apical membrane and subapical cytoplasm of CD cells of the inner medulla, and the degree of increase was dominant in apical membrane. In the V2R antagonist group, only faint staining of apical membrane and weak labeling of cytoplasm of CD cells of the inner medulla were observed. These changes in the localization and protein amount of AQP-CD by dehydration and V2R antagonist were quantitatively confirmed by immunogold studies and immunoblot analysis of the inner medulla. The present results indicate that the distribution and amount of AQP-CD in the CD cells are regulated by vasopressin V2 receptor.
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PMID:Expression and distribution of aquaporin of collecting duct are regulated by vasopressin V2 receptor in rat kidney. 752 48

In patients with liver cirrhosis, impaired water and sodium excretion has been incriminated in the pathogenesis of ascites formation. Increased reabsorption of water in the distal nephron has been shown to play an important role in water retention in cirrhotic rat kidneys. Recently, a complementary DNA (cDNA) for the vasopressin-regulated water channel (the aquaporin of the apical membrane of the kidney collecting duct [AQP-CD]) has been cloned. It is suggested that AQP-CD plays an important role in renal water handling. Therefore, in the present study, to investigate the pathogenic role of the water channel in water retention in liver cirrhosis, gene expression of AQP-CD in the kidney was evaluated in cirrhotic rats. Liver cirrhosis was induced by an intraperitoneal administration of carbon tetrachloride twice a week for 12 weeks in 14 rats. Messenger RNA expression of AQP-CD in whole kidney homogenates determined by Northern blot hybridization was significantly increased in cirrhotic rats (147%; P < .01) and dehydrated rats (206%; P < .0001) compared with control rats. Protein expression of AQP-CD in the homogenates of kidney medulla determined by Western blot analysis was significantly increased in cirrhotic rats (203%; P < .03) compared with control rats. Furthermore, mRNA expression of AQP-CD in the kidney showed a significant correlation with the volume of ascites in cirrhotic rats (r = .62, P < .02). No significant difference was observed in water intake, urinary volume, serum osmolality, serum sodium, and creatinine clearance between control and cirrhotic rats, suggesting that dehydration was unlikely in cirrhotic rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Increased gene expression of water channel in cirrhotic rat kidneys. 752 8

The aquaporins transport water through membranes of numerous tissues, but the molecular mechanisms for sensing changes in extracellular osmolality and regulating water balance in brain are unknown. We have isolated a brain aquaporin by homology cloning. Like aquaporin 1 (AQP1, also known as CHIP, channel-forming integral membrane protein of 28 kDa), the deduced polypeptide has six putative transmembrane domains but lacks cysteines at the known mercury-sensitive sites. Two initiation sites were identified encoding polypeptides of 301 and 323 amino acids; expression of each in Xenopus oocytes conferred a 20-fold increase in osmotic water permeability not blocked by 1 mM HgCl2, even after substitution of cysteine at the predicted mercury-sensitive site. Northern analysis and RNase protection demonstrated the mRNA to be abundant in mature rat brain but only weakly detectable in eye, kidney, intestine, and lung. In situ hybridization of brain localized the mRNA to ependymal cells lining the aqueduct, glial cells forming the edge of the cerebral cortex and brainstem, vasopressin-secretory neurons in supraoptic and paraventricular nuclei of hypothalamus, and Purkinje cells of cerebellum. Its distinctive expression pattern implicates this fourth mammalian member of the aquaporin water channel family (designated gene symbol, AQP4) as the osmoreceptor which regulates body water balance and mediates water flow within the central nervous system.
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PMID:Molecular characterization of an aquaporin cDNA from brain: candidate osmoreceptor and regulator of water balance. 752 31

Among water channel proteins (aquaporins), aquaporin-collecting duct (AQP-CD) is the vasopressin-regulated water channel. Vasopressin causes cAMP production in the renal collecting duct cells, and this is believed to lead to exocytic insertion of water channel into the apical membrane (shuttle hypothesis). AQP-CD contains a consensus sequence for cAMP-dependent protein kinase, residues at positions 253-256 (Arg-Arg-Gln-Ser). To determine the role of this site, Ser-256 was substituted for Ala, Leu, Thr, Asp, or Glu by site-directed mutagenesis. In Xenopus oocytes injected with wild-type or mutated AQP-CD cRNAs, osmotic water permeability (Pf) was 4.8-7.7 times higher than Pf of water-injected oocytes. Incubation with cAMP plus forskolin or direct cAMP injection into the oocytes increased Pf of wild-type, but not mutated, AQP-CD-expressing oocytes, whereas the amounts of AQP-CD expression were similar in wild and mutated types as identified by Western blot analysis. In vitro phosphorylation studies of AQP-CD proteins expressed in oocyte showed that cAMP-dependent protein kinase phosphorylated wild-type, but not mutated, AQP-CD proteins. Phosphoamino acid analysis revealed that this phosphorylation occurred at the serine residue. Moreover, phosphorylation of AQP-CD protein in intact rat kidney medulla tissues was stimulated by incubation with cAMP. Our data suggest that cAMP stimulates water permeability of AQP-CD by phosphorylation. This process may contribute to the vasopressin-regulated water permeability of collecting duct in addition to the apical insertion of AQP-CD by exocytosis.
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PMID:cAMP-dependent phosphorylation stimulates water permeability of aquaporin-collecting duct water channel protein expressed in Xenopus oocytes. 753 30

Congenital nephrogenic diabetes insipidus is a recessive hereditary disorder characterized by the inability of the kidney to concentrate urine in response to vasopressin. Recently, we reported mutations in the gene encoding the water channel of the collecting duct, aquaporin-2 (AQP-2) causing an autosomal recessive form of nephrogenic diabetes insipidus (NDI). Expression of these mutant AQP-2 proteins (Gly64Arg, Arg187Cys, Ser216Pro) in Xenopus oocytes revealed nonfunctional water channels. Here we report further studies into the inability of these missense AQP-2 proteins to facilitate water transport in Xenopus oocytes. cRNAs encoding the missense AQPs were translated with equal efficiency as cRNAs encoding wild-type AQP-2 and were equally stable. Arg187Cys AQP2 was more stable and Gly6-4Arg and Ser216Pro AQP2 were less stable when compared to wild-type AQP2 protein. On immunoblots, oocytes expressing missense AQP-2 showed, besides the wild-type 29 kDa band, an endoplasmic reticulum-retarded form of AQP-2 of approximately 32 kD. Immunoblots and immunocytochemistry demonstrated only intense labeling of the plasma membranes of oocytes expressing wild-type AQP-2. Therefore, we conclude that in Xenopus oocytes the inability of Gly64-Arg, Arg187Cys or Ser216Pro substituted AQP-2 proteins to facilitate water transport is caused by an impaired routing to the plasma membrane.
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PMID:Water channels encoded by mutant aquaporin-2 genes in nephrogenic diabetes insipidus are impaired in their cellular routing. 753 61

The identification, characterization, and mutational analysis of three different genes, namely the prepro-arginine-vasopressin-neurophysin II gene (prepro-AVP-NPII), the arginine-vasopressin receptor 2 gene (AVPR2), and the vasopressin-sensitive water channel gene (aquaporin-2, AQP2), provide the basis for our understanding of three different hereditary forms of diabetes insipidus: autosomal dominant neurogenic diabetes insipidus, X-linked nephrogenic diabetes insipidus, and autosomal recessive nephrogenic diabetes insipidus, respectively. These advances provide diagnostic tools for physicians caring for these patients.
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PMID:Molecular biology of diabetes insipidus. 754 Nov 87

The cellular and subcellular localization and expression of a kidney collecting duct water channel, aquaporin (AQP)-CD, were examined in the kidneys of hydrated and dehydrated rats by immunostaining, Northern blot analysis, and radioimmunoassay. In hydrated rat kidneys, AQP-CD was selectively found in the collecting duct principal cells and inner medullary collecting duct cells, but not in the intercalated cells. At a light microscopic level, AQP-CD was diffusely present in a granular pattern throughout the cytoplasm of the collecting duct cells with a preferential accumulation in subapical regions. By immunoelectron microscopy, AQP-CD was frequently demonstrated along membranes of small vesicles in the subapical cytoplasm and occasionally along the basolateral membranes of these cells. However, immunolabeling was sparse on the apical membranes. In dehydrated rats, AQP-CD immunostaining was intensified in the subapical cytoplasm of the collecting duct cells, along with increases in the number and size of AQP-CD-bearing vesicles in the subapical regions and with increment of labeling along the apical membranes. The increase in the amount of AQP-CD in the collecting duct cells of dehydrated rat kidneys was quantitatively confirmed by elevation of AQP-CD at mRNA and protein levels. The AQP-CD localization is consistent with the predicted site of the antidiuretic hormone (ADH)-regulated water channel in the collecting ducts and the increase in AQP-CD at mRNA and protein levels by dehydration may account for high concentration of urine in dehydrated subjects.
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PMID:Localization and expression of a collecting duct water channel, aquaporin, in hydrated and dehydrated rats. 754 39

A group of transmembrane proteins that are related to the major intrinsic protein of lens fibers (MIP26) have been named "aquaporins" to reflect their role as water channels. These proteins are located at strategic membrane sites in a variety of epithelia, most of which have well-defined physiological functions in fluid absorption or secretion. However, some aquaporins have been localized in cell types where their role is at present unknown. Most of the aquaporins are delivered to the plasma membrane in a non-regulated (constitutive) fashion, but AQP2 enters the regulated exocytotic pathway and its membrane expression is controlled by the action of the antidiuretic hormone, vasopressin. These pathways of constitutive versus regulated delivery to the plasma membrane have been reconstituted in transfected LLC-PK1 epithelial cells, indicating that the information encoded within the protein sequence is sufficient to allow sorting of newly synthesized protein into distinct intracellular vesicles. Finally, different members of the aquaporin family can be targeted to apical, basolateral or both apical and basolateral plasma membrane domains of polarized epithelial cells. This implies that signals for the polarized targeting of these proteins also is located in non-homologous regions of these similar proteins. Thus, future investigations on the aquaporin family of proteins will provide important information not only on the physiology of membrane transport processes in many cell types, but also on the targeting and trafficking signals that allow proteins to enter distinct intracellular vesicular pathways in epithelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cellular distribution of the aquaporins: a family of water channel proteins. 758 54

Congenital nephrogenic diabetes insipidus (NDI) is a rare inherited disorder characterized by the inability of the kidney to concentrate urine in response to vasopressin (AVP). Following the recent characterization of the cDNA and genomics sequences encoding the human V2 receptor to AVP (AVPR2), X-linked NDI has been found to be due to mutations in the AVPR2 gene that maps to the chromosome Xq28 region. To date more than 30 mutations, insertions or deletions have been reported in independent families, without any significant differences in the phenotypic expression of the disease. The AVPR2 is a member of the superfamily of 7 transmembrane domain, G protein-coupled receptor, linked to cyclic AMP second messenger system. Other types of inheritance have been described in NDI, and recently, a mutation of the aquaporin-2 gene, encoding a water channel of the renal collecting duct, has been reported in an autosomal recessive form of NDI.
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PMID:[Hereditary nephrogenic diabetes insipidus]. 764 Jul 59

Concentration of urine in mammals is regulated by the antidiuretic hormone vasopressin. Binding of vasopressin to its V2 receptor leads to the insertion of water channels in apical membranes of principal cells in collecting ducts. In nephrogenic diabetes insipidus (NDI), the kidney fails to concentrate urine in response to vasopressin. A male patient with an autosomal recessive form of NDI was found to be a compound heterozygote for two mutations in the gene encoding aquaporin-2, a water channel. Functional expression studies in Xenopus oocytes revealed that each mutation resulted in nonfunctional water channel proteins. Thus, aquaporin-2 is essential for vasopressin-dependent concentration of urine.
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PMID:Requirement of human renal water channel aquaporin-2 for vasopressin-dependent concentration of urine. 814 Apr 21


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