Protein kinase C activator PMA reduces the Ca(2+) response to antigen stimulation of adherent RBL-2H3 mucosal mast cells by inhibiting depletion of intracellular Ca(2+) stores.

Kuchtey J, Fewtrell C
J Cell Physiol. 1999 181 (1): 113-23

PMID: 10457359 · DOI:10.1002/(SICI)1097-4652(199910)181:1<113::AID-JCP12>3.0.CO;2-7

Activation of protein kinase C has been shown to reduce the Ca(2+) responses of a variety of cell types. In most cases, the reduction is due to inhibition of Ca(2+) influx, but acceleration of Ca(2+) efflux and inhibition of Ca(2+) store depletion by protein kinase C activation have also been described. For adherent RBL-2H3 mucosal mast cells, results from whole-cell patch clamp experiments suggest that protein kinase C activation reduces Ca(2+) influx, while experiments with intact, fura-2-loaded cells suggest that Ca(2+) influx is not affected. Here we present single-cell data from Ca(2+) imaging experiments with adherent RBL-2H3 cells, showing that antigen-stimulated Ca(2+) responses of phorbol 12-myristate 13-acetate (PMA)-treated cells are more transient than those of control cells. PMA also reduced the response to antigen in the absence of extracellular Ca(2+), indicating that depletion of intracellular Ca(2+) stores is inhibited. If PMA was added after stores had been depleted by thapsigargin, a small decrease in [Ca(2+)](i) was observed, consistent with a slight inhibition of Ca(2+) influx. However, the major effect of PMA on the antigen-stimulated Ca(2+) response is to inhibit depletion of intracellular Ca(2+) stores. We also show that inhibition of protein kinase C did not enhance the Ca(2+) response to antigen, suggesting that inhibition of the Ca(2+) response by activation of protein kinase C does not contribute to the physiological response to antigen.

Copyright 1999 Wiley-Liss, Inc.

MeSH Terms (14)

Antigens Calcium Cell Adhesion Cell Line Enzyme Activation Fluorescent Dyes Fura-2 Logistic Models Mast Cells Patch-Clamp Techniques Protein Kinase C Stimulation, Chemical Tetradecanoylphorbol Acetate Thapsigargin

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