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)

The substance P (SP) analogues [DArg1, DPhe5, DTrp7,9, Leu11] SP (AntD) and [Arg6, DTrp7,9, MePhe8] SP (6-11) (AntG) inhibit the action of many different neuropeptides including SP. These analogues might be useful in the treatment of small cell lung cancer but their mechanism of action is unclear. Here, we analyzed the effect of AntD and AntG on neuropeptide vs. guanosine 5'-3-O-(thio) triphosphate (GTP gamma S)-stimulated inositol phosphate generation in permeabilized Swiss 3T3 cells. AntD inhibited vasopressin and bombesin stimulated inositol phosphate formation (IC50 of 0.75 microM and 2 microM, respectively). Similarly, AntG inhibited vasopressin-stimulated inositol phosphate generation with an IC50 of 1 microM. Strikingly, neither AntD up to 10 microM nor AntG up to 20 microM was able to inhibit GTP gamma S-stimulated inositol phosphate generation. Dose-response curves of neuropeptide-induced inositol phosphate generation were dramatically displaced to the right by either 10 microM AntD or 20 microM AntG. However, neither antagonist affected the dose response of GTP gamma S-stimulated inositol phosphate generation. Furthermore, 20 microM AntD had no effect on AIF-4-induced inositol phosphates in COS-1 cells transfected with G alpha q. AntD inhibited [3H]vasopressin binding competitively in intact Swiss 3T3 cells and both AntD and AntG inhibited [3H]vasopressin binding in Swiss 3T3 and rat liver membranes. Scatchard analysis revealed that AntD inhibited vasopressin binding by reducing receptor affinity without affecting receptor number in both intact and membrane preparations of Swiss 3T3 cells. The results strongly suggest that SP analogues AntD and AntG block the action of the Ca2+ mobilizing neuropeptides at the receptor level, rather than inhibiting G protein-stimulated inositol phosphate production.
 ...
PMID:Substance P-related antagonists inhibit vasopressin and bombesin but not 5'-3-O-(thio)triphosphate-stimulated inositol phosphate production in Swiss 3T3 cells. 753 71

A selective polyclonal antibody directed toward the C-terminal decapeptide common to the alpha subunits of Gq and G11 G proteins (G alpha q/G alpha 11) was prepared and used to investigate the subcellular distribution fo these proteins in WRK1 cells, a rat mammary tumor cell line. In immunoblots, the antibody recognized purified G alpha q and G alpha 11 proteins and labeled only two bands corresponding to these alpha subunits. Functional studies indicated that this antibody inhibited vasopressin- and guanosine 5'-[alpha-thio]triphosphate-sensitive phospholipase C activities. Immunofluorescence experiments done with this antibody revealed a filamentous labeling corresponding to intracytoplasmic and perimembranous actin-like filament structures. Colocalization of G alpha q/G alpha 11 and F-actin filaments (F-actin) was demonstrated by double-labeling experiments with anti-G alpha q/G alpha 11 and anti-actin antibodies. Immunoblot analysis of membrane, cytoskeletal, and F-actin-rich fractions confirmed the close association of G alpha q/G alpha 11 with actin. Large amounts of G alpha q/G alpha 11 were recovered in the desmin- and tubulin-free F-actin-rich fraction obtained by a double depolymerization-repolymerization cycle. Disorganization of F-actin filaments with cytochalasin D preserved G alpha q/G alpha 11 and F-actin colocalization but partially inhibited vasopressin- and fluoroaluminate-sensitive phospholipase C activity, suggesting that actin-associated G alpha q/G alpha 11 proteins play a role in signal transduction.
 ...
PMID:Close association of the alpha subunits of Gq and G11 G proteins with actin filaments in WRK1 cells: relation to G protein-mediated phospholipase C activation. 766 4

Recent studies have shown that G proteins are a potential regulatory site in the transmembrane signaling cascade. The aim of this study was to examine the effects of prolonged agonist exposure on expression of the Gq class of G protein alpha subunits (G alpha q/G alpha 11) in cultured rat vascular smooth muscle cells (VSMC). Treatment with 100 nM angiotensin II (Ang II) led to a substantial sustained down-regulation of cellular levels of immunologically detectable G alpha q/G alpha 11 by 50% within 6 hr. The effect of Ang II was dose dependent with an EC50 of 2 nM and was specifically blocked by the vascular type-1 Ang II receptor-specific antagonist losartan. The Ang II-induced reduction in cellular levels of G protein alpha subunits was specific for G alpha q/G alpha 11. The calcium ionophore ionomycin or activators of ubiquitous protein kinases (phorbol-12-myristate-13-acetate, forskolin, and 8-bromo-cGMP) did not mimic the effects of Ang II. However, [Arg8]vasopressin also induced a significant loss in cellular G alpha q/G alpha 11 levels. Ang II-induced G alpha q/G alpha 11 down-regulation was reversed by prevention of cellular receptor processing with phenylarsine oxide or chronic potassium depletion. The effects of Ang II on G alpha q/G alpha 11 levels were inhibited when protein kinase C activity was abolished. G alpha q mRNA levels were down-regulated by 30% after 4-hr incubation with Ang II, in part by transcriptional regulation. Although a short term vasopressin pretreatment had no effect on inositol-1,4,5-trisphosphate (IP3) generation in response to subsequent Ang II stimulation, a partial heterologous desensitization of the IP3 response was induced after a long term vasopressin pretreatment, which concurrently down-regulated cellular G alpha q/G alpha 11 levels. Homologous desensitization of IP3 generation on a second Ang II stimulation was observed after both a short and long term Ang II pretreatment. In conclusion, prolonged exposure to Ang II induces down-regulation of cellular G alpha q/G alpha 11 levels in intact VSMC. The effect of Ang II appears to be mediated by the signaling pathway sensitive to inhibition of receptor processing. The present study raises the possibility that agonist-induced G alpha q/G alpha 11 down-regulation participates in the mechanism of long term desensitization of the G alpha q/G alpha 11-mediated signaling system in VSMC.
 ...
PMID:Prolonged exposure to agonist results in a reduction in the levels of the Gq/G11 alpha subunits in cultured vascular smooth muscle cells. 856 18

The V2 vasopressin receptor (V2R) activates the mitogen activated protein kinases (MAPK) ERK1/2 through a mechanism involving the scaffolding protein beta arrestin. Here we report that this activating pathway is independent of G alpha s, G alpha i, G alpha q or G betagamma and that the V2R-mediated activation of G alpha s inhibits ERK1/2 activity in a cAMP/PKA-dependent manner. In the HEK293 cells studied, the beta arrestin-promoted activation was found to dominate over the PKA-mediated inhibition of the pathway, leading to a strong vasopressin-stimulated ERK1/2 activation. Despite the strong MAPK activation and in contrast with other GPCR, V2R did not induce any significant increase in DNA synthesis, consistent with the notion that the stable interaction between V2R and beta arrestin prevents signal propagation to the nucleus. Beta arrestin was found to be essential for the ERK1/2 activation, indicating that the recruitment of the scaffolding protein is necessary and sufficient to initiate the signal in the absence of any other stimulatory cues. Based on the use of selective pharmacological inhibitors, dominant negative mutants and siRNA, we conclude that the beta arrestin-dependent activation of ERK1/2 by the V2R involves c-Src and a metalloproteinase-dependent trans-activation event. These findings demonstrate that beta arrestin is a genuine signalling initiator that can, on its own, engage a MAPK activation machinery upon stimulation of a GPCR by its natural ligand.
 ...
PMID:The V2 vasopressin receptor stimulates ERK1/2 activity independently of heterotrimeric G protein signalling. 1685 42