Topic
Rhc80267
About: Rhc80267 is a research topic. Over the lifetime, 19 publications have been published within this topic receiving 587 citations. The topic is also known as: RHC 80267 & RHC-80267.
Papers
TL;DR: It is concluded that PC12 cells express a diacylglycerol-activated, non-selective cation channel and expression of this channel function correlates with expression of the TRP-3 andTRP-6 proteins, which have been shown previously to be activated by diacy l Glycerol when expressed heterologously in animal cells.
Abstract: The structures, and mechanisms of activation, of plasma membrane intracellular-messenger-activated, non-selective cation channels in animal cells are not well understood. The PC12 adrenal chromaffin cell line is a well-characterized example of a nerve cell. In PC12 cells, 1-oleolyl-2-acetyl-sn-glycerol (OAG), a membrane-permeant analogue of diacylglycerol, initiated the inflow of Ca(2+), Mn(2+) and Sr(2+). Acetylcholine and thapsigargin initiated the inflow of Ca(2+) and Mn(2+), but not of Sr(2+). The activation of bivalent cation inflow by OAG: (i) was mimicked by another membrane-permeant diacylglycerol analogue, 1,2-dioctanoyl-sn-glycerol, but not by the membrane-impermeant analogue 1-stearoyl-2-arachidonyl-sn-glycerol; (ii) was not blocked by staurosporin or chelerythrine, inhibitors of protein kinase C; (iii) was enhanced by RHC80267 and {"type":"entrez-nucleotide","attrs":{"text":"R50922","term_id":"812824","term_text":"R50922"}}R50922, inhibitors of diacylglycerol lipase and diacylglycerol kinase respectively; and (iv) was inhibited by extracellular Ca(2+). When OAG was added after acetylcholine, the effect of OAG on Ca(2+) inflow was over-and-above that induced by acetylcholine. 2-Aminoethyl diphenylborate (2-APB) inhibited Ca(2+) inflow initiated by either acetylcholine or thapsigargin, but not that initiated by OAG. Flufenamic acid inhibited OAG-initiated, but not acetylcholine-initiated, Ca(2+) and Mn(2+) inflow. OAG-initiated Ca(2+) inflow was less sensitive to inhibition by SK&F96365 than acetylcholine-initiated Ca(2+) inflow. In polyadenylated RNA prepared from PC12 cells, mRNA encoding TRP (transient receptor potential) proteins 1-6 was detected by reverse transcriptase (RT)-PCR, and in lysates of PC12 cells the endogenous TRP-6 protein was detected by Western blot analysis. It is concluded that PC12 cells express a diacylglycerol-activated, non-selective cation channel. Expression of this channel function correlates with expression of the TRP-3 and TRP-6 proteins, which have been shown previously to be activated by diacylglycerol when expressed heterologously in animal cells [Hofmann, Obukhov, Schaefer, Harteneck, Gudermann, and Schultz (1999) Nature (London) 397, 259-263].
100 citations
TL;DR: Data suggest that the signal transduction pathway of the Ep receptor includes the activation of phospholipases A2 and C, resulting in the liberation of DAG and arachidonate and the subsequent formation of LTB4 and 12-HETE.
Abstract: Erythropoietin (Ep) is the peptide growth factor whose actions on the erythroid progenitor cell induce terminal differentiation. However, the intracellular signaling system that is activated by Ep is poorly understood. Our previous studies have implicated the lipoxygenase metabolites of arachidonic acid in the actions of Ep. In this study, we report an early (30 s to 5 min) increase in levels of two lipoxygenase metabolites: leukotriene B4 (LTB4; 3- to 5-fold) and 12-hydroxyeicosatetraenoic acid (12-HETE; 2-fold). These responses were blocked by an antibody to Ep, by lipoxygenase inhibitors, or by 1,6-di[O-(carbamoyl)cyclohexanone oxime]hexane (RHC80267), an inhibitor of diacylglycerol (DAG) lipase. RHC 80267 also significantly inhibited Ep-mediated proliferation. Ep induced the release of [3H]arachidonic acid from cellular phospholipids at 5 min and also increased DAG accumulation at 1 min with a maximum increase of 68.2% over control seen at 30 min. No increase in levels of inositol trisphosphate or phosphatidic acid was observed in response to Ep. Taken together, these data suggest that the signal transduction pathway of the Ep receptor includes the activation of phospholipases A2 and C, resulting in the liberation of DAG and arachidonate and the subsequent formation of LTB4 and 12-HETE.
55 citations
TL;DR: It is shown that comprehensive pharmacological elimination of this activity in brain cryosections by methyl arachidonylfluorophosphonate or hexadecylsulphonyl fluoride results in endocannabinoid‐mediated CB1 receptor activity, which can be visualized by functional autoradiography.
Abstract: In neuronal signalling mediated by the endocannabinoid 2-arachidonoylglycerol, both synthetic and inactivating enzymes operate within close proximity to the G(i/o)-coupled pre-synaptic CB(1) receptors, thus allowing for rapid onset and transient duration of this lipid modulator. In rat brain, 2-arachidonoylglycerol is inactivated mainly via hydrolysis by serine hydrolase inhibitor-sensitive monoacylglycerol lipase activity. We show in this study that comprehensive pharmacological elimination of this activity in brain cryosections by methyl arachidonylfluorophosphonate or hexadecylsulphonyl fluoride results in endocannabinoid-mediated CB(1) receptor activity, which can be visualized by functional autoradiography. URB597, a specific inhibitor of anandamide hydrolysis proved ineffective. TLC indicated that the bioactivity resided in 2-arachidonoylglycerol-containing fraction and gas chromatography-mass spectroscopy detected elevated levels of monoacylglycerols, including 2-arachidonoylglycerol in this fraction. Although two diacylglycerol lipase inhibitors, tetrahydrolipstatin (THL) and RHC80267, blocked the bulk of 2-arachidonoylglycerol accumulation in methyl arachidonylfluorophosphonate-treated sections, only THL reversed the endocannabinoid-dependent CB(1) receptor activity. Further studies indicated that at the used concentrations, THL rather specifically antagonized the CB(1) receptor. These findings confirm that in brain sections there is preservation of enzymatic pathways regulating the production of endogenous receptor ligands. Furthermore, the presently described methodology may serve as an elegant and intuitive approach to identify novel membrane-derived lipid modulators operating in the CNS.
32 citations
TL;DR: The pH stability assay and circular dichroism spectroscopic analysis revealed that Rv3203 protein is more stable in acidic condition.
Abstract: The Rv3203 (LipV) of Mycobacterium tuberculosis (Mtb) H37Rv, is annotated as a member of Lip family based on the presence of characteristic consensus esterase motif ‘GXSXG’. In vitro culture studies of Mtb H37Ra indicated that expression of Rv3203 gene was up-regulated during acidic stress as compared to normal whereas no expression was observed under nutrient and oxidative stress conditions. Therefore, detailed characterization of Rv3203 was done by gene cloning and its further expression and purification as his-tagged protein in microbial expression system. The enzyme was purified to homogeneity by affinity chromatography. It demonstrated broad substrate specificity and preferentially hydrolyzed p-nitrophenyl myristate. The purified enzyme demonstrated an optimum activity at pH 8.0 and temperature 50 °C. The specific activity, Km and Vmax of enzyme was determined to be 21.29 U mg−1 protein, 714.28 μM and 62.5 μmol ml−1 min−1, respectively. The pH stability assay and circular dichroism spectroscopic analysis revealed that Rv3203 protein is more stable in acidic condition. Tetrahydrolipstatin, a specific lipase inhibitor and RHC80267, a diacylglycerol lipase inhibitor abolished the activity of this enzyme. The catalytic triad residues were determined to be Ser50, Asp180 and His203 residues by site-directed mutagenesis.
28 citations
Journal Article•
TL;DR: A crucial role for the arachidonate-generating enzymes in the induction of lytic activity of NK cells directly or by leading to generation of additional mediators that can play a role in the context of NK cell activation and cytotoxic functions is supported.
Abstract: NKR-P1A protein has been implicated in the triggering of NK-mediated natural killing contributing to target cell recognition by NK cells. The aim of the present work was to assess whether NKR-P1A receptor triggering also induced arachidonic acid (AA) generation and to determine the possible role of this event on granule release and cytotoxicity. We demonstrated that activation of fresh peripheral blood rat NK cells by cross-linking with the anti-NKR-P1A 3.2.3 mAb induced calcium-dependent AA release, which is due to the activation of cytosolic phospholipase A2 (cPLA2), secretory phospholipase A2 (sPLA2), and diacylglycerol/monoacylglycerol lipase. We also documented the presence of a type II sPLA2 activity in the supernatant fluids from NKR-P1A-activated rat NK cells, suggesting that AA and lysophospholipids could be mobilized from the outside of the cell. The involvement of AA-generating enzymes in NKR-P1A-induced cytotoxic functions was also investigated. Treatment of effector cells with arachidonyl trifluoromethylketone, a cPLA2 inhibitor; p-bromophenacylbromide, a sPLA2 inhibitor; or RHC80267, a diacylglycerol lipase inhibitor, led to a partial inhibition of the redirected lysis against P815 target cells as well the granule content release induced by NKR-P1A cross-linking. A complete abolishment of these events was observed when the cells were simultaneously incubated with all three inhibitors. Taken together, our results support a crucial role for the arachidonate-generating enzymes in the induction of lytic activity of NK cells directly or by leading to generation of additional mediators that can play a role in the context of NK cell activation and cytotoxic functions.
26 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2020 | 1 |
| 2019 | 1 |
| 2014 | 1 |
| 2012 | 2 |
| 2011 | 1 |
| 2010 | 1 |