| Dexamethasone up-regulates A3 adenosine receptors in rat basophilic leukemia (RBL-2H3) cells. | |
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MedLine Citation:
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PMID: 7730645 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The cross-linking of surface IgE receptors by multi-functional Ags promotes the degranulation of mast cells. Previous studies have indicated that the nucleoside adenosine potentiates this response by activating putative A3 adenosine receptors (AR) coupled to phospholipase C in mast cells or their cultured analogues, rat basophilic leukemia (RBL-2H3) cells. Moreover, it has been shown that exposure of RBL-2H3 cells to dexamethasone attenuated antigen-mediated mast cell degranulation, but potentiated the response elicited by adenosine. To determine whether the A3AR is a potential site of action of dexamethasone, we have assessed the status of these receptors in RBL-2H3 cells treated with and without dexamethasone. Treatment with dexamethasone (100 nM) for 24 h resulted in an increase in the number of A3AR to 217 +/- 50% of control. The increased receptor expression was both time- and concentration-dependent, with optimal increases observed following 16 h of treatment and using 100 nM of dexamethasone. No increase in the level of the A2aAR was detectable following dexamethasone treatment. Northern blotting studies indicated a 2.7 +/- 0.3-fold increase in A3AR mRNA in RBL-2H3 cells treated with dexamethasone for 24 h. Dexamethasone also increased the expression of G protein alpha i2, alpha i3, alpha s, and beta subunits by two- to threefold. Activation of the A3AR by aminophenylethyladenosine (APNEA) following dexamethasone treatment enhanced the production of inositol phosphates and the mobilization of intracellular Ca2+. From these data, it is concluded that dexamethasone increases the expression of both A3AR and G proteins in RBL-2H3 cells which contributes to the enhanced response to adenosine. |
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Authors:
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V Ramkumar; M Wilson; D N Dhanraj; T W Gettys; H Ali |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Journal of immunology (Baltimore, Md. : 1950) Volume: 154 ISSN: 0022-1767 ISO Abbreviation: J. Immunol. Publication Date: 1995 May |
Date Detail:
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Created Date: 1995-05-31 Completed Date: 1995-05-31 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 2985117R Medline TA: J Immunol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 5436-43 Citation Subset: AIM; IM |
Affiliation:
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Department of Pharmacology, Southern Illinois University School of Medicine, Springfield 62794, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Blotting, Western Calcium / analysis Dexamethasone / pharmacology* GTP-Binding Proteins / biosynthesis*, drug effects Inositol Phosphates / analysis Leukemia, Basophilic, Acute Mast Cells / drug effects* Rats Receptors, Purinergic P1 / biosynthesis*, drug effects* Tumor Cells, Cultured Up-Regulation beta-N-Acetylhexosaminidases / secretion |
| Grant Support | |
ID/Acronym/Agency:
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DK42486/DK/NIDDK NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Inositol Phosphates; 0/Receptors, Purinergic P1; 50-02-2/Dexamethasone; 7440-70-2/Calcium; EC 3.2.1.52/beta-N-Acetylhexosaminidases; EC 3.6.1.-/GTP-Binding Proteins |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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