Document Detail


Dexamethasone up-regulates A3 adenosine receptors in rat basophilic leukemia (RBL-2H3) cells.
MedLine Citation:
PMID:  7730645     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
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.
Authors:
V Ramkumar; M Wilson; D N Dhanraj; T W Gettys; H Ali
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of immunology (Baltimore, Md. : 1950)     Volume:  154     ISSN:  0022-1767     ISO Abbreviation:  J. Immunol.     Publication Date:  1995 May 
Date Detail:
Created Date:  1995-05-31     Completed Date:  1995-05-31     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  2985117R     Medline TA:  J Immunol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  5436-43     Citation Subset:  AIM; IM    
Affiliation:
Department of Pharmacology, Southern Illinois University School of Medicine, Springfield 62794, USA.
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MeSH Terms
Descriptor/Qualifier:
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:
DK42486/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
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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