RT Journal Article
SR Electronic
T1 GTP-binding protein G alpha Z: its down-regulation by dexamethasone and its credentials as a mediator of antigen-induced responses in RBL-2H3 cells.
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 473
OP 479
VO 40
IS 4
A1 M Hide
A1 H Ali
A1 S R Price
A1 J Moss
A1 M A Beaven
YR 1991
UL http://molpharm.aspetjournals.org/content/40/4/473.abstract
AB We have investigated the possible role of guanine nucleotide-binding proteins in the process of antigen-induced exocytosis in a cultured rat mast cell line, RBL-2H3 cells. The mRNAs for the alpha subunits of the guanine nucleotide-binding proteins G alpha S (short and long forms), G alpha i-2, G alpha i-3, and G alpha Z were detected by hybridization with G alpha-specific oligonucleotide probes. The corresponding proteins were identified in membranes of RBL-2H3 cells on the basis of size, immunoreactivity with specific antibodies, and their ability to serve as substrates for ADP-ribosylation by cholera toxin or pertussis toxin. Treatment of cells with as little as 10(-9) to 10(-7) M dexamethasone markedly decreased the amount of G alpha Z mRNA and membrane G alpha Z, as well as the responsiveness of the cells to antigen stimulation. In the same cells, the exposure to dexamethasone caused an increase in the amounts of certain other G alpha subunits, particularly G alpha i-3, and in the responsiveness of the cells to an adenosine analog, N(ethylcarboxamido)-adenosine. Because of the apparent decrease in G alpha Z mRNA and protein in dexamethasone-treated cells and the fact that neither cholera toxin nor pertussis toxin inhibits the stimulatory signals to antigen [J. Biol. Chem. 265:745-753 (1990)], we suggest that G alpha Z is a potential candidate for regulating the early signals in antigen-stimulated RBL-2H3 cells.