Functional contributions of the FcepsilonRIalpha and FepsilonRIgamma subunit domains in FcepsilonRI-mediated signaling in mast cells.

The functional contributions of the alpha and gamma subunit domains of the high affinity receptor for IgE (Fcepsilon-RI) were determined following chimeric receptor aggregation. Chimeric receptors of the extracellular (EC) and cytoplasmic tail (CT) domains of FcepsilonRI and the IL-2R p55 subunit (I) were constructed and stably expressed in RBL-2H3 cells. Signaling (inositol phosphate production, tyrosine phosphorylation, Ca2+ mobilization, and secretion of histamine and arachidonic acid metabolites) via alpha/gamma/gamma or I/gamma/gamma was similar to the native rat receptor, and both were shown to associate with endogenous FcepsilonRIbeta and FcepsilonRIgamma subunits.

Functional characterization of the signal transduction events mediated by Fc epsilon RI alpha and gamma chimeric receptors.

Chimeric receptors containing the Fc epsilon RI alpha and gamma subunit domains were constructed, stably transfected into RBL-2H3 cells, and characterized for the biochemical events which are elicited upon receptor aggregation. Chimeric receptors containing the extracellular (EC) domain of the human Fc epsilon RI alpha subunit, or the EC domain of the p55 subunit of the interleukin-2 receptor were fused to the human Fc epsilon RI gamma subunit transmembrane and cytoplasmic (CT) domains or only the CT domain. The chimeras generated included alpha/gamma/gamma, I/gamma/gamma, alpha/I/gamma or I/I/gamma.

Conservation of signal transduction mechanisms via the human Fc epsilon RI alpha after transfection into a rat mast cell line, RBL 2H3.

The high affinity receptor for IgE (Fc epsilon RI) is present on mast cells and basophils, and the aggregation of IgE-occupied receptors by Ag is responsible for the release of allergic mediators. The Fc epsilon RI is composed of at least three different subunits, alpha, beta, and gamma, with the alpha subunit binding IgE. The series of biochemical events linking receptor aggregation to the release of mediators has not been fully delineated.

Differential effects of propranolol on the IgE-dependent, or calcium ionophore-stimulated, phosphoinositide hydrolysis and calcium mobilization in a mast (RBL 2H3) cell line.

Our previous studies demonstrated that propranolol, an inhibitor of phosphatidic acid phosphohydrolase (PAPase) (EC 3.1.3.

Activation of phospholipase D in a rat mast (RBL 2H3) cell line. A possible unifying mechanism for IgE-dependent degranulation and arachidonic acid metabolite release.

RBL 2H3 cells (a model of mast cell function) were sensitized with anti-TNP IgE (0.5 micrograms/ml) and triggered to secrete both histamine and arachidonic acid (AA) metabolites by the addition of TNP-OVA (0 to 100 ng/ml). After a 3-min delay, the release of both groups of mediators proceeded in a parallel manner.