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

It has recently been demonstrated that an established cell line from pig kidney, LLC-PK1, is a useful model for the study of vasopressin-sensitive adenylate cyclase (Roy, C., and Ausiello, D. A. (1981) J. Biol. Chem. 256, 3415-3422; Roy, C., Hall, D., Karish, M., and Ausiello, D. A. (1981) J. Biol. Chem. 256, 3423-3427). The present study on the regulation of this enzyme has led to the demonstration of the modulation of vasopressin-stimulated adenylate cyclase by Ca2+-calmodulin. The characteristics of calmodulin regulation were similar to those described for other enzymes: (a) activation required micromolar quantities of free Ca2+; (b) maximal enzyme rates were altered but not the Km for hormone activation; (c) activity was inhibitable by trifluoperazine; and (d) activation was dependent on the Mg2+ concentration. These findings should help to define the mechanisms of action of several agents known to alter vasopressin-sensitive adenylate cyclase and cell Ca2+ content.
 ...
PMID:Regulation of vasopressin-sensitive adenylate cyclase by calmodulin. 727 76

The aquaporins (AQPs) are a family of homologous water-channel proteins that can be inserted into epithelial cell plasma membranes either constitutively (AQP1) or by regulated exocytosis following vasopressin stimulation (AQP2). LLC-PK1 porcine renal epithelial cells were stably transfected with cDNA encoding AQP2 (tagged with a C-terminal c-Myc epitope) or rat kidney AQP1 cDNA in an expression vector containing a cytomegalovirus promoter. Immunofluorescence staining revealed that AQP1 was mainly localized to the plasma membrane, whereas AQP2 was predominantly located on intracellular vesicles. After treatment with vasopressin or forskolin for 10 min, AQP2 was relocated to the plasma membrane, indicating that this relocation was induced by cAMP. The location of AQP1 did not change. The basal water permeability of AQP1-transfected cells was 2-fold greater than that of nontransfected cells, whereas the permeability of AQP2-transfected cells increased significantly only after vasopressin treatment. Endocytotic uptake of fluorescein isothiocyanate-coupled dextran was stimulated 6-fold by vasopressin in AQP2-transfected cells but was only slightly increased in wild-type or AQP1-transfected cells. This vasopressin-induced endocytosis was inhibited in low-K+ medium, which selectively affects clathrin-mediated endocytosis. These water channel-transfected cells represent an in vitro system that will allow the detailed dissection of mechanisms involved in the processing, targeting, and trafficking of proteins via constitutive versus regulated intracellular transport pathways.
 ...
PMID:Constitutive and regulated membrane expression of aquaporin 1 and aquaporin 2 water channels in stably transfected LLC-PK1 epithelial cells. 754 77

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)
 ...
PMID:Cellular distribution of the aquaporins: a family of water channel proteins. 758 54

The calcitonin receptor has been proposed to function as an extracellular Ca2+ concentration ([Ca2+]o) sensor (Stroop, S. D., Thompson, D. L., Kuestner, R. E., and Moore, E. E. (1993) J. Biol. Chem. 268, 19927-19930). To test this hypothesis we studied the LLC-PK1 renal tubular cells and the PC1 cells, a cell line stably transfected with the cloned porcine calcitonin receptor. [Ca2+]i was measured by fura-2 single cell microfluorometry. Addition to the cells equilibrated in 1.25 mM Ca(2+)-containing media of 1-10 mM extracellular Ca2+ did not result in a significant increase of [Ca2+]i. Treatment with 10(-7) M salmon calcitonin (sCT) elicited a rapid, persistent elevation of [Ca2+]i. Addition of 1-10 mM extracellular Ca2+ in the presence of sCT induced a significant [Ca2+]i elevation, about 10-fold that observed in the absence of the hormone. Ca2+ influx was inhibited by lanthanum. The rise of [Ca2+]i at elevated [Ca2+]o was not due to a Ca2+ sensing mechanism with release of Ca2+ from intracellular stores, since it was prolonged, and was not abolished by prior depletion of Ca2+ stores with 10(-6)M thapsigargin. On the contrary, this agent potentiated Ca2+ influx after addition of 1-10 mM Ca2+ by 13-fold versus control. Prior stimulation of [Ca2+]i with 10(-7) M arginine-vasopressin had similar effects, enhancing the subsequent Ca2+ influx. Enhancement of Ca2+ influx by sCT was confirmed by increased Mn2+ quenching of fura-2 fluorescence. In conclusion, arginine-vasopressin or calcitonin enhance Ca2+ influx in LLC-PK1 cells via a Ca2+ release-activated conductance, probably dependent upon capacitative Ca2+ entry. Thus, these effects are not unique to the calcitonin receptor and argue against the receptor functioning as a [Ca2+]o sensor.
 ...
PMID:Calcitonin increases cytosolic free calcium concentration via capacitative calcium influx. 762 75

When we treated vasopressin-sensitive vascular smooth muscle cells (A10 cells) and kidney cells (LLC-PK1 cells) with hypertonic sucrose and vasopressin, we observed a decrease in the internalization of radiolabeled vasopressin into these cells and an increase in the amount of second messenger present in these cells following vasopressin stimulation. In A10 cells exposed to hypertonic sucrose, there was an increase in the amount of cellular inositol phosphates accumulated in response to vasopressin compared with cells not exposed to hypertonic sucrose. Similarly, in hypertonic sucrose-treated LLC-PK1 cells, vasopressin increased the amount of adenosine 3',5'-cyclic monophosphate (cAMP) present within the cells compared with LLC-PK1 cells not exposed to hypertonic sucrose. Hypertonic sucrose treatment inhibited receptor-mediated endocytosis in both these cell lines. Hypertonic sucrose alone did not increase the basal amounts of inositol phosphates or cAMP present in A10 or LLC-PK1 cells, respectively. Hypertonic sucrose treatment inhibits receptor endocytosis and increases second messenger concentrations in vasopressin-sensitive cells.
 ...
PMID:Hypertonic sucrose treatment enhances second messenger accumulation in vasopressin-sensitive cells. 768 May 31

Several lines of evidence suggest that the Golgi apparatus is involved in Ca2+ regulation in renal epithelial LLC-PK1 cells. Laser scanning confocal microscopy (LSCM) was employed to establish that a prominent perinuclear region is occupied mainly by the Golgi apparatus in this cell line. LSCM measurements in individual cells with the ionized Ca2+ indicator calcium green revealed that stimulation of LLC-PK1 cells with arginine vasopressin (AVP) resulted in the elevation of ionized Ca2+ levels. However, the vasopressin-induced rise in ionized Ca2+ was attenuated if the Golgi apparatus was disassembled by pretreating the cells with brefeldin A (BFA). Subcellular measurements of total Ca2+ with ion microscopy in cryogenically prepared cells indicated that 1) within 1 min of AVP treatment significant quantities of sequestered Ca2+ were released from the perinuclear Golgi region and 2) the BFA treatment reduced the total Ca2+ stored in the Golgi region. These observations indicate that the Golgi apparatus is sensitive to hormonal stimulation and may play important roles in intracellular Ca2+ regulation in LLC-PK1 cells.
 ...
PMID:Golgi apparatus is involved in intracellular Ca2+ regulation in epithelial LLC-PK1 cells. 776 5

We characterized the endothelin (ET) receptor subtypes responsible for signal transduction in cultured porcine kidney epithelial LLC-PK1 cells. Both ET-1 (IC50, 43 pM) and ET-3 (IC50, 46 pM) inhibited the binding of [125I]ET-1 to LLC-PK1 cells to a similar extent. The binding affinity of LLC-PK1 cells was about 10,000 times higher for the ETB antagonist BQ-788 [N-cis-2,6-dimethyl-piperidinocarbonyl-L-tau-metylleucyl-D-+ ++Nin- methoxycarbonyltryptophanyl-D-norleucine] (IC50, 1.3 nM) than for the ETA antagonist BQ-123 [cyclo-(D-Trp-D-Asp-Pro-D-Val-Leu)] (IC50, 14 microM). ET-1 enhanced cyclic GMP (cGMP) production, but reduced vasopressin- and forskolin-stimulated cyclic AMP (cAMP) production. Both effects of ET-1 were antagonized by BQ-788, but not by BQ-123. The cAMP decrease, but not the cGMP increase, in response to ET-1 was inhibited by pertussis toxin, suggesting that the former response is mediated by pertussis toxin-sensitive Gi, whereas the latter is mediated by a pertussis toxin-insensitive G-protein. Therefore, the ETB receptors in LLC-PK1 cells couple to the two types of signal transduction cascades to reduce cAMP production and stimulate cGMP production via distinct G-proteins. ET-1 and probably also ET-3 may play a role in the regulation of renal epithelial transport by decreasing cAMP and increasing cGMP.
 ...
PMID:Endothelin ETB receptors couple to two distinct signaling pathways in porcine kidney epithelial LLC-PK1 cells. 793 50

The effect of a conventional antibiotic (penicillin/streptomycin) mixture on the widely used kidney epithelial cell line, LLC-PK1, was investigated by measuring growth and intracellular free calcium. Free calcium concentration was the same in cells cultured for 3 to 7 wk with ("plus") and without ("minus") antibiotics both at rest and when challenged with high (14 mM) external calcium. When exposed to vasopressin, minus cells exhibited significantly smaller calcium transients than plus cells. A similar difference existed for transients elicited by a calcium ionophore, 4-br-A23187. After longer periods of culture (> 20 wk), minus cells grew slower than plus cells but on reaching confluence (minus cells took 1 day longer) the morphologies and viabilities were indistinguishable. The finding that culture with penicillin/streptomycin reversibly modified some properties of LLC-PK1 cells, at least partly through altered calcium homeostasis, is of importance for workers using this cell model to study drug effects and raises the general possibility of similar effects on other cultured cells.
 ...
PMID:Altered free calcium transients in pig kidney cells (LLC-PK1) cultured with penicillin/streptomycin. 795 10

We previously described a new iodinated vasopressin analogue (N epsilon-[125I]L-Tyr-[Lys8]-vasopressin) with high affinity for the vasopressin V1 and V2 isoreceptors. The aim of the present study was: i) to analyse the degradation pathway of N epsilon-[125I]L-Tyr-[Lys8]-vasopressin and (ii) to look for an effective inhibitor of radioligand degradation. N epsilon-[125I]L-Tyr-[Lys8]-vasopressin was processed in a temperature-dependent manner by crude cell membranes from LLC-PK1 cells. Only one degradation product was seen using RP-HPLC. The degradation product co-eluted with monoiodotyrosine. The stereoisomer, N epsilon-[125I]D-Tyr-[Lys8]-vasopressin, underwent the same degradation process. Bacitracin prevented degradation at doses as low as 40 mg/l without alterating the binding affinity.
 ...
PMID:Effect of bacitracin on the degradation of a vasopressin receptor ligand with high affinity for the V1 and V2 vasopressin isoreceptors. 800 78

The lateral mobility of membrane integral receptors has been implicated as playing a significant role in signal transduction. The adenylate cyclase-coupled vasopressin V2 receptor has been shown to be highly laterally mobile in membranes of LLC-PK1 renal epithelial cells at physiological temperature using a fluorescent vasopressin agonist, with lateral mobility of the V2 receptor proposed to play a role in both adenylate cyclase activation and ligand induced receptor internalization and down-regulation. This study reports the synthesis and characterization of two new fluorescent antagonists [(beta-mercapto-beta,beta-cyclopentamethylene propionic acid)1,D-Tyr2,Ile4,Lys9(N6-fluoresceinylaminothiocarbonyl )]AVP (FL-AVP-anta) and [(beta-mercapto-beta,beta-cyclopentamethylene propionic acid)1,D-Tyr2,Ile4,Lys9(N6-tetramethylrhodamylaminothioca rbonyl)]AVP (TR-AVP-anta) for the V2 receptor. The latter was used to determine the parameters of lateral mobility of the V2 receptor in the non-activated antagonist-occupied form. Using fluorescence photobleaching techniques, results were largely comparable to those for agonist-occupied receptor, indicating high mobility at 37 degrees C. Antagonistic properties of the V2 receptor ligands are apparently not related to decreased receptor lateral mobility. Photobleaching measurements, however, did show that in contrast to V2 agonist, V2 antagonist did not induce receptor immobilization due to aggregation with time at 37 degrees C, indicating that this could be of mechanistic importance in the internalization process.
 ...
PMID:Lateral mobility of the antagonist-occupied V2 vasopressin receptor in membranes of renal epithelial cells. 808 94


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>