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)

In the cortical collecting duct (CCD), arginin vasopressin (AVP) has been shown to increase the number and activity of basolateral Na+-K+-ATPase by recruiting or activating a latent pool of pumps. However, the precise mechanism of this phenomenon is still unknown. The aim of this study was to investigate whether this AVP-induced increase in basolateral Na+-K+-ATPase could depend on a dephosphorylation process. To this purpose, the effect of protein serine/threonine phosphatase (PP) inhibitors was examined on both the specific 3H-ouabain binding (to evaluate the number of pumps in the basolateral membrane) and the ouabain-dependent 86Rb uptake (to evaluate pump functionality) in the presence or absence of AVP. In addition, the activity of two PP, PP1 and PP2A, was measured and the influence of AVP was examined on both enzymes. Experiments have been performed on mouse CCD isolated by microdissection. Results show that inhibition of PP2A prevents the AVP-induced increase in the number and activity of Na+-K+-ATPases, independent of an effect on the apical cell sodium entry. In addition, AVP rapidly increased the activity of PP2A without effect on PP1. These data suggest that PP2A is implied in the regulation of Na+-K+-ATPase activity by AVP in the CCD and that the AVP-dependent increase in the number of Na+-K+-ATPases is mediated by a PP2A-dependent dephosphorylation process.
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PMID:Role of protein phosphatase in the regulation of Na+-K+-ATPase by vasopressin in the cortical collecting duct. 884 18

The aquaporin-2 (AQP2) vasopressin water channel is translocated to the apical membrane upon vasopressin stimulation. Phosphorylation of serine 256 of AQP2 by cAMP-dependent protein kinase has been shown, but its relation to vasopressin-regulated translocation has not been elucidated. To address this question, wild type (WT) AQP2 and a mutant with alanine in place of serine 256 of AQP2 (S256A) were expressed in LLC-PK1 cells by electroporation. Measurements by a stopped-flow light-scattering method revealed that the osmotic water permeability (Pf) of LLC-PK1 cells transfected with WT was 69.6 +/- 6.5 microm/s (24.8 +/- 2.2 microm/s for mock-transfected), and stimulation by 500 microM 8-(4-chlorophenylthio)-cAMP increased the Pf by 85 +/- 12%. When S256A AQP2 was transfected, the cAMP-dependent increase in the Pf was only 8 +/- 5%. After cAMP stimulation, the increase in surface expression of AQP2 determined by surface biotin labeling was 4 +/- 10%, significantly less than that for WT (88 +/- 5%). In addition, an in vivo [32P]orthophosphate labeling assay demonstrated significant phosphorylation of WT AQP2 and only minimal phosphorylation of S256A AQP2 in LLC-PK1 cells. Our results indicated that serine 256 of AQP2 is necessary for regulatory exocytosis and that cAMP-responsive redistribution of AQP2 may be regulated by phosphorylation of AQP2.
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PMID:Phosphorylation of serine 256 is required for cAMP-dependent regulatory exocytosis of the aquaporin-2 water channel. 916 47

cAMP and Ca2+ acted together with the acute phase cytokine interleukin-1beta (IL-1beta) to inhibit hepatocyte DNA replication. At sub-basal activity of cAMP-dependent protein kinase (PKA), neither IL-1beta nor the Ca2+-elevating hormone vasopressin affected hepatocyte proliferation. Basal level of PKA activity permitted IL-1beta action. Increased PKA activity also permitted vasopressin action and sensitized further towards IL-1beta, which acted at 10-50 pM concentrations. Vasopressin acted via Ca2+/calmodulin-dependent protein kinase II (CaMKII), and its action was mimicked by the serine/threonine phosphatase inhibitor microcystin, which activates CaMKII. Inhibitors (KN93 and KT5926) of CaMKII selectively counteracted the effects of vasopressin and microcystin on hepatocyte proliferation at concentrations similar to those required to inhibit CaMKII in vitro. Two-dimensional gel electrophoresis of 32P-prelabeled hepatocytes revealed a common set of proteins phosphorylated in response to vasopressin and microcystin. Their phosphorylation was counteracted by CaMKII inhibitor (KT5926). Phosphorylation of the CaMKII substrate phenylalanine hydroxylase (PAH; EC 1.14.16.1) was used as an endogenous marker of CaMKII activation. It was found that treatment of the cells with vasopressin or microcystin increased the phosphorylation of PAH, and that the vasopressin-induced PAH phosphorylation was inhibited by KT5926. In conclusion, the Ca2+-elevating hormone vasopressin potentiated the antiproliferative effects of cAMP and IL-1beta through CaMKII activation.
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PMID:Synergistic antiproliferative actions of cyclic adenosine 3',5'-monophosphate, interleukin-1beta, and activators of Ca2+/calmodulin-dependent protein kinase in primary hepatocytes. 932 53

Receptor recycling plays a critical role in the regulation of cellular responsiveness to environmental stimuli. Agonist-promoted phosphorylation of G protein-coupled receptors has been related to their desensitization, internalization, and sequestration. Dephosphorylation of internalized G protein-coupled receptors by cytoplasmic phosphatases has been shown to be pH-dependent, and it has been postulated to be necessary for receptors to recycle to the cell surface. The internalized V2 vasopressin receptor (V2R) expressed in HEK 293 cells is an exception to this hypothesis because it does not recycle to the plasma membrane for hours after removal of the ligand. Because this receptor is phosphorylated only by G protein-coupled receptor kinases (GRKs), the relationship between recycling and GRK-mediated phosphorylation was examined. A nonphosphorylated V2R, truncated upstream of the GRK phosphorylation sites, rapidly returned to the cell surface after removal of vasopressin. Less-drastic truncations of V2R revealed the presence of multiple phosphorylation sites and suggested a key role for a serine cluster present at the C terminus. Replacement of any one of Ser-362, Ser-363, or Ser-364 with Ala allowed quantitative recycling of full-length V2R without affecting the extent of internalization. Examination of the stability of phosphate groups incorporated into the recycling S363A mutant V2Rs revealed that the recycling receptor was dephosphorylated after hormone withdrawal, whereas the wild-type V2R was not, providing molecular evidence for the hypothesis that GRK sites must be dephosphorylated prior to receptor recycling. These experiments uncovered a role for GRK phosphorylation in intracellular sorting and revealed a GRK-dependent anchoring domain that blocks V2R recycling.
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PMID:A serine cluster prevents recycling of the V2 vasopressin receptor. 948 66

Familial diabetes insipidus (FDI) is a syndrome of central vasopressin deficiency that is inherited in an autosomal dominant manner and that typically becomes clinically apparent in the first decade of life. Two novel mutations of the vasopressin gene have been identified in two previously unstudied kindreds with FDI. In each kindred, the inheritance of the FDI phenotype was consistent with an autosomal dominant mode of inheritance. In each proband, the diagnosis of central diabetes insipidus had been confirmed previously with a water deprivation protocol. After extraction of genomic DNA from each individual, the three exons of the vasopressin gene were separately amplified by PCR and directly sequenced using an automated dye termination method. In the proband and two other carriers of one kindred, a heterozygous C to T mutation was identified at nucleotide 1857. This is predicted to produce a serine to phenylalanine substitution at residue 56 of the vasopressin-related neurophysin peptide encoded by the mutated allele. The mutation also abolished an MspI site in the vasopressin sequence, and analysis of genomic DNA from eight members of the kindred (five with FDI) confirmed segregation of the mutation with the FDI phenotype. Another member of the kindred, a 13-month-old infant, also has the heterozygous C to T mutation, but a formal water balance study showed no evidence of diabetes insipidus. In the proband of the other kindred, a heterozygous G to A mutation was identified at nucleotide 1873. This mutation would be predicted to cause a cysteine to tyrosine substitution at residue 61 of the neurophysin encoded by the mutated allele. This heterozygous mutation was confirmed by the presence of an RsaI restriction site in one vasopressin allele in two members of the kindred. Therefore, two novel heterozygous mutations of the vasopressin gene have been identified in FDI kindreds. In one kindred, an asymptomatic carrier infant was identified and will require continued observation to determine whether she will develop clinical diabetes insipidus. The presence of these two novel mutations in a region of the vasopressin gene where other FDI mutations have been reported suggests that the part of the neurophysin peptide encoded by these sequences may be critically important in the appropriate expression of vasopressin.
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PMID:Two novel mutations of the vasopressin gene associated with familial diabetes insipidus and identification of an asymptomatic carrier infant. 981 75

The human V2 vasopressin receptor contains one consensus site for N-linked glycosylation at asparagine 22 in the predicted extracellular amino terminal segment of the protein. This segment also contains clusters of serines and threonines that are potential sites for O-glycosylation. Mutagenesis of asparagine 22 to glutamine abolished N-linked glycosylation of the V2 receptor (N22Q-V2R), without altering its function or level of expression. The N22Q-V2R expressed in transfected cells migrated in denaturing acrylamide gels as two protein bands with a difference of 7000 Da. Protein labeling experiments demonstrated that the faster band could be chase to the slower one suggesting the presence of O-linked sugars. Sialidase treatment of membranes from cells expressing the N22Q-V2R or of immunoprecipitated metabolically labeled V2R accelerated the migration of the protein in acrylamide gels demonstrating the existence of O-glycosylation, the first time this type of glycosylation has been found in a G protein coupled receptor. Synthesis of metabolically labeled receptor in the presence of 1 mM phenyl-N-acetyl-alpha-D-galactosaminide, a competitive inhibitor of N-acetyl-alpha-D-galactose and N-acetylneuraminic acid transferases, also produced a receptor that migrated faster in denaturing gels. Serines and threonines present in the amino terminus were analyzed by alanine scanning mutagenesis to identify the acceptor sites. O-glycosylation was found at most serines and threonines present in the amino terminus. Because the disappearance of a site opened the availability of others to the transferases, the exact identification of the acceptor sites was not feasible. The wild type V2R expressed in HEK 293, COS, or MDCK cells underwent N- and O-linked glycosylation. The mutant V2R bearing all serine/threonine substitutions by alanine at the amino terminus yielded a receptor functionally indistinguishable from the wild type protein, whose mobility in polyacrylamide gels was no longer affected by sialidase treatment.
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PMID:O-Glycosylation of the V2 vasopressin receptor. 1036 43

Autosomal dominant neurohypophyseal diabetes insipidus is caused by mutations in the gene encoding the vasopressin precursor protein, prepro-vasopressin-neurophysin II. We analyzed the molecular consequences of a mutation (DeltaG227) recently identified in a Swiss kindred that destroys the translation initiation codon. In COS-7 cells transfected with the mutant cDNA, translation was found to initiate at an alternative ATG, producing a truncated signal sequence that was functional for targeting and translocation but was not cleaved by signal peptidase. The mutant precursor was completely retained within the endoplasmic reticulum. The uncleaved signal did not affect folding of the neurophysin portion of the precursor, as determined by its protease resistance. However, formation of disulfide-linked aggregates indicated that it interfered with the formation of the disulfide bond in vasopressin, most likely by blocking its insertion into the hormone binding site of neurophysin. Preventing disulfide formation in the vasopressin nonapeptide by mutation of cysteine 6 to serine was shown to be sufficient to cause aggregation and retention. These results indicate that the DeltaG227 mutation induces translation of a truncated signal sequence that cannot be cleaved but prevents correct folding and oxidation of vasopressin, thereby causing precursor aggregation and retention in the endoplasmic reticulum.
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PMID:Mechanism of endoplasmic reticulum retention of mutant vasopressin precursor caused by a signal peptide truncation associated with diabetes insipidus. 1038 95

Vasopression-induced phosphorylation of serine 256 of the aquaporin-2 (AQP2) water channel triggers translocation of the protein from cystolic reservoir vesicles to the apical membrane of collecting duct principal cells. Dileucine motifs are located in the sixth transmembrane domain (6TM) of AQP2 and are known as the signal sequence for internalization, sorting from the trans-Golgi network to endosomes/lysosomes, and basolateral sorting. In this study, involvement of 6TM in vasopressin-induced translocation of the protein was investigated. A series of mutations in 6TM of AQP2 was introduced to rat cDNA and expressed in LLC-PK(1) cells. Immunofluorescence microscopy indicated that the mutant AQP2 proteins were retained in the cytoplasm after vasopressin stimulation, which actually promoted the plasma membrane expression of wild-type protein. Immunoelectron microscopy showed that the mutant AQP2 proteins reached the endosomes but did not reach the plasma membrane. These results demonstrate that 6TM has essential domains for vasopressin-induced translocation from endosomes to the plasma membrane.
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PMID:Mutations in sixth transmembrane domain of AQP2 inhibit its translocation induced by vasopression. 1071 May 44

Physiological vasoconstrictor concentrations of Arg8-vasopressin (AVP, 10-100 pM) stimulate oscillations (spikes) in cytosolic free Ca2+ concentration ([Ca2+]i) in A7r5 rat vascular smooth muscle cells. These Ca2+ spikes are dependent on L-type voltage-sensitive Ca2+ channels and increase in frequency with increasing AVP concentration. The signal transduction pathway responsible for this effect was examined in fura-2-loaded A7r5 cell monolayers. The serine/threonine phosphatase inhibitor calyculin A (5 nM) sensitized A7r5 cells to AVP, resulting in the stimulation of Ca2+ spiking by 1-10 pM AVP. Calyculin A alone did not stimulate Ca2+ spiking. The protein kinase C (PKC) activator 4beta-phorbol 12-myristate 13-acetate (PMA, 100 pM to 200 nM), also stimulated Ca2+ spiking and this effect was additive with a submaximal concentration of AVP (50 pM). The PKC inhibitors Ro-31-8220 (1 microM) and calphostin C (250 nM) completely blocked the stimulation of Ca2+ spiking by either PMA or AVP. alpha, beta, gamma, delta, epsilon, zeta and &lamdda; isoforms of PKC were detected in A7r5 cells by Western blot analysis. Time-dependent redistribution of PKC-alpha, -delta and -epsilon isoforms between the membrane and cytosolic fractions occurred in response to 100 pM AVP. Pretreatment for 24 h with 1 microM PMA downregulated expression of PKC-alpha and -delta, but not PKC-epsilon, and prevented the Ca2+-spiking responses to either 1 nM PMA or 100 pM AVP. Neither the release of intracellular Ca2+ by 1 microM AVP nor the increase in [Ca2+]i in response to elevated extracellular [K+] was prevented by the PMA pretreatment. We conclude that PKC activation is a necessary step in the signal transduction pathway linking low concentrations of AVP to Ca2+ spiking in A7r5 cells.
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PMID:Ca2+ signalling in rat vascular smooth muscle cells: a role for protein kinase C at physiological vasoconstrictor concentrations of vasopressin. 1079 Jan 61

In collecting duct principal cells, aquaporin 2 (AQP2) is shuttled from intracellular vesicles to the plasma membrane upon vasopressin (VP) stimulation. VP activates adenylyl cyclase, increases intracellular cAMP, activating protein kinase A (PKA) to phosphorylate AQP2 on the COOH-terminal residue, serine 256. Using rat kidney slices and LLC-PK1 cells stably expressing AQP2 (LLC-AQP2 cells), we now show that AQP2 trafficking can be stimulated by cAMP-independent pathways. In these systems, the nitric oxide (NO) donors sodium nitroprusside (SNP) and NONOate and the NO synthase substrate L-arginine mimicked the effect of VP, stimulating relocation of AQP2 from cytoplasmic vesicles to the plasma membrane. Unlike VP, these other agents did not increase intracellular cAMP. However, SNP increased intracellular cGMP, and exogenous cGMP stimulated AQP2-membrane insertion. Atrial natriuretic factor, which signals via cGMP, also stimulated AQP2 translocation. The VP and SNP effects were blocked by the kinase inhibitor H89. SNP did not stimulate membrane insertion of AQP2 in LLC-PK1 cells expressing the phosphorylation-deficient mutant 256SerAla-AQP2, indicating that phosphorylation of Ser256 is required for signaling. Both PKA and cGMP-dependent protein kinase G phosphorylated AQP2 on this COOH-terminal residue in vitro. These results demonstrate a novel, cAMP-independent and cGMP-dependent pathway for AQP2 membrane insertion in renal epithelial cells.
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PMID:Nitric oxide and atrial natriuretic factor stimulate cGMP-dependent membrane insertion of aquaporin 2 in renal epithelial cells. 1106 64


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