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)

AQP-CD is a vasopressin-regulated water channel expressed exclusively in the renal collecting duct. We have previously shown that AQP-CD is present in the apical plasma membrane and subapical vesicles of collecting duct cells, consistent with membrane-shuttling mechanisms that have been proposed to explain the short-term action of [Arg8] vasopressin (AVP) to regulate apical water permeability. We propose here that AVP may also have long-term actions on the collecting duct to regulate the expression of the AQP-CD water channel. We used immunoblotting, immunohistochemistry, and in vitro perfusion of renal tubules to investigate water channel regulation in collecting ducts of diabetes insipidus (Brattleboro) rats treated with a 5-day infusion of AVP or vehicle. Immunoblotting and immunohistochemistry demonstrated that collecting ducts of vehicle-infused Brattleboro rats had markedly reduced expression of AQP-CD relative to normal rats. In response to AVP infusion there was a nearly 3-fold increase in AQP-CD expression as detected by immunoblotting. Immunocytochemistry demonstrated that the increased expression was predominantly in the apical plasma membrane and subapical vesicles of collecting duct cells. Inner medullary collecting ducts of AVP-infused Brattleboro rats displayed a 3-fold increase in osmotic water permeability relative to vehicle-infused controls, in parallel with the change in AQP-CD expression. Based on these findings, we conclude that (i) long-term infusion of AVP, acting either directly or indirectly, regulates expression of the AQP-CD water channel and (ii) AQP-CD is the predominant AVP-regulated water channel.
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PMID:Regulation of collecting duct water channel expression by vasopressin in Brattleboro rat. 752 27

The water channel CHIP28 accounts for the high water permeability of proximal tubules and thin descending limbs of Henle; a homologous water channel, WCH-CD, in the apical membrane of collecting duct principal cells, may be the vasopressin-sensitive water channel. We show here that one antiserum, raised against CHIP28, immunostains the basolateral membrane of collecting duct principal cells, in addition to staining CHIP28 in other cells. This serum was named anti-basolateral integral protein (anti-BLIP) to distinguish it from other anti-CHIP28 antisera. By Western blotting, BLIP serum recognized both CHIP28 and MIP26, and it stained lens fibers, which contain MIP26 but not CHIP28. BLIP antiserum immunoprecipitated a 28-kDa band, a broad 35- to 50-kDa band, and an approximately 16-kDa band from kidney papilla. It also stained the basolateral membrane of gastric parietal cells, which were not stained with anti-CHIP28 or anti-MIP26 antibodies. BLIP antiserum immunoprecipitated a 28-kDa protein band from stomach; this protein was not precipitated by anti-CHIP28 antibodies. These results suggest that basolateral membranes of principal cells and parietal cells contain a protein(s) that shares common epitopes with CHIP28 and MIP26. Finally, BLIP but not CHIP28 antiserum stained mesothelial (but not epithelial) cells of toad urinary bladder, a further indication that the BLIP antiserum recognizes a protein distinct from CHIP28.
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PMID:A basolateral CHIP28/MIP26-related protein (BLIP) in kidney principal cells and gastric parietal cells. 752 36

Vasopressin-regulated water permeability of the kidney collecting duct is a key component of the urine concentration machinery. Recently, a cDNA for AQP-CD, the vasopressin-regulated water channel, initially reported as WCH-CD, has been isolated (K. Fushimi, S. Uchida, Y. Hara, Y. Hirata, F. Marumo, and S. Sasaki. Nature Lond. 361: 549-552, 1993). AQP-CD was expressed in oocyte membrane using a Xenopus expression vector, and functional characteristics of AQP-CD were examined. Osmotic water permeability (Pf) of oocytes expressing AQP-CD was 138 +/- 19 microns/s (mean +/- SE), 12 times greater than the control (11 +/- 3 microns/s), 90% inhibited by 0.3 mM HgCl2, and weakly temperature dependent (energy of activation for Pf was 4.0 kcal/mol). Urea influx measured from 15-min [14C]urea uptake by oocytes injected with AQP-CD/expression vector 1 cRNA was 86 +/- 17% of the control. Two-electrode voltage-clamp experiments revealed insignificant ion conductance of AQP-CD. Immunoblots of membranes from rat kidney medulla and oocytes expressing AQP-CD using anti-AQP-CD COOH-terminal antibody showed a 29-kDa protein and 35- to 50-kDa high-molecular-mass forms. Immunohistochemistry showed apical and subapical localization of AQP-CD in the collecting duct principal cells. Our results indicated that AQP-CD is a 29-kDa protein, a selective water channel, distinct from a urea channel, and localized to the membranes of vasopressin-sensitive components in kidney collecting duct principal cells.
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PMID:Functional characterization and cell immunolocalization of AQP-CD water channel in kidney collecting duct. 752 58

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

Water reabsorption in mammalian renal tubules is mediated by channel-forming membrane glycoproteins termed aquaporins (AQP). So far three different kinds of AQP have been described in renal tubules. AQP CHIP is localized to the luminal and contraluminal membranes of the proximal tubule and descending thin limb cells, i.e., in tubule segments that exhibit a constitutive high permeability to water that is insensitive to vasopressin. AQP-CD is present in subapical vesicles and the luminal membrane of collecting duct principal cells. Its intracellular distribution depends on vasopressin or hydration status of the animal and, thus, may represent the vasopressin-sensitive water channel. The basolateral integral protein (BLIP) may represent the vasopressin-insensitive water channel in basolateral membrane of collecting duct principal cells. The exact localization of a recently cloned homologue, WCH3, which may be either related to BLIP or represent yet another kind of AQP, is not known. Heterogeneity of aquaporins in the renal tubule may provide a molecular basis for the treatment of certain diseases with disturbances in water homeostasis.
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PMID:Water transport in renal tubules is mediated by aquaporins. 753 21

Water excretion by the kidney is regulated by the peptide hormone vasopressin. Vasopressin increases the water permeability of the renal collecting duct cells, allowing more water to be reabsorbed from collecting duct urine to blood. Despite long-standing interest in this process, the mechanism of the water permeability increase has remained undetermined. Recently, a molecular water channel (AQP-CD) has been cloned whose expression appears to be limited to the collecting duct. Previously, we immunolocalized this water channel to the apical plasma membrane (APM) and to intracellular vesicles (IVs) of collecting duct cells. Here, we test the hypothesis that vasopressin increases cellular water permeability by inducing exocytosis of AQP-CD-laden vesicles, transferring water channels from IVs to APM. Rat collecting ducts were perfused in vitro to determine water permeability and subcellular distribution of AQP-CD in the same tubules. The collecting ducts were fixed for immunoelectron microscopy before, during, and after exposure to vasopressin. Vasopressin exposure induced increases in water permeability and the absolute labeling density of AQP-CD in the APM. In parallel, the APM:IV labeling ratio increased. Furthermore, in response to vasopressin withdrawal, AQP-CD labeling density in the APM and the APM:IV labeling ratio decreased in parallel to a measured decrease in osmotic water permeability. We conclude that vasopressin increases the water permeability of collecting duct cells by inducing a reversible translocation of AQP-CD water channels from IVs to the APM.
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PMID:Vasopressin increases water permeability of kidney collecting duct by inducing translocation of aquaporin-CD water channels to plasma membrane. 753 4

According to the 'shuttle hypothesis', vasopressin increases the water permeability of renal epithelial cells by exocytotic fusion of vesicles containing the water channel AQP-CD with the apical plasma membrane, whereas withdrawal of vasopressin results in endocytotic uptake of AQP-CD. The proteins involved in the redistribution of AQP-CD have not been identified. With a panel of monoclonal antibodies, we detected Rab3-, Rab5a- and synaptobrevin II-like proteins in a kidney preparation enriched in AQP-CD-containing vesicles. The synaptobrevin II-like proteins is not identical with the ubiquitous cellubrevin. Rab3- and synaptobrevin II- but not Rab5a-like proteins were co-enriched with AQP-CD. The data suggest that the proteins involved in hormonal regulation of water permeability in kidney epithelial cells are identical or similar to those involved in regulated exocytosis in secretory cells.
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PMID:Identification of Rab3-, Rab5a- and synaptobrevin II-like proteins in a preparation of rat kidney vesicles containing the vasopressin-regulated water channel. 754 Jan 51

Several membranes of the kidney are highly water permeable, thereby enabling this organ to retain large quantities of water. Recently, the molecular identification of water channels responsible for this high water permeability has finally been accomplished. At present, four distinct renal water channels have been identified, all members of the family of major intrinsic proteins. Aquaporin 1 (AQP1), aquaporin 2 (AQP2) and the mercury-insensitive water channel (MIWC) are water-selective channel proteins, whereas the fourth, referred to as aquaporin 3 (AQP3), permits transport of urea and glycerol as well. Furthermore, a putative renal water channel (WCH3) has been found. AQP1 is expressed in apical and basolateral membranes of proximal tubules and descending limbs of Henle, AQP2 predominantly in apical membranes of principal and inner medullary collecting duct cells and AQP3 in basolateral membranes of kidney collecting duct cells. MIWC is expressed in the inner medulla of the kidney and has been suggested to be localised in the vasa recta. The human genes encoding AQP1 and AQP2 have been cloned, permitting deduction of their amino acid sequence, prediction of their two-dimensional structure by hydropathy analysis, speculations on their way of functioning and DNA analysis in patients with diseases possibly caused by mutant aquaporins. Mutations in the AQP1 gene were recently detected in clinically normal individuals, a finding which contradicts the presumed vital importance of this protein. Mutations in the AQP2 gene were shown to cause autosomal recessive nephrogenic diabetes insipidus. The renal unresponsiveness to arginine vasopressin, which characterises this disease, is in accordance with the assumption that AQP2 is the effector protein of the renal vasopressin pathway.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Discovery of aquaporins: a breakthrough in research on renal water transport. 754 Aug 50

The effect of vasopressin on subcellular localization of AQP-CD and AQP3 water channels was examined in thirsted Brattleboro rats by immunohistochemistry and immunoelectron microscopy. AQP-CD was mainly present in the cytoplasm of the collecting duct cells in association with cytoplasmic vesicles but was sparse in the apical membrane in control vehicle-injected rats. In rats given vasopressin 15 min before death, the number of immunogold particles for AQP-CD in the apical membrane increased significantly (P < 0.002) from 1.8 +/- 0.2 to 10.0 +/- 0.4/microns with a significant decrease (P < 0.05) of cytoplasmic labeling from 32.6 +/- 6.4 to 24.6 +/- 5.6/microns 2, indicating that AQP-CD is the vasopressin-regulated water channel predicted by the "shuttle" hypothesis. In contrast, AQP3 was restricted to the basolateral membrane of the collecting duct cells, and the labeling density of AQP3 was unchanged by vasopressin treatment, indicating that AQP3 is constitutively expressed and may maintain high water permeability of the basolateral membrane.
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PMID:Vasopressin increases AQP-CD water channel in apical membrane of collecting duct cells in Brattleboro rats. 754 41

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


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