Regulation of (1-3)-beta-glucan-stimulated Ca2+ influx by protein kinase Cin NR8383 alveolar macrophages

Stimulation of (1-3)-beta-glucan receptors results in Ca2+ influx through r eceptor-operated channels in alveolar macrophages (AMs), but the mechanism( s) regulating Ca2+ influx is still undefined. In this study we investigated the role of protein kinase C (PKC) regulation of Ca2+ influx in the NR8383 AM cell line using the particulate (1-3)-beta-glucan receptor agonist zymo san. PKC inhibition with calphostin C (CC) or bisindolymaleimide I (BSM) si gnificantly reduced zymosan-induced Ca2+ influx, whereas activation of PKC with phorbol-12-myristate 13-acetate (PMA) or 1,2-dioctanoyl-sn-glycerol (D OG) mimicked zymosan, inducing a concentration-dependent Ca2+ influx. This influx was dependent on extracellular Ca2+ and inhibited by the receptor-op erated Ca2+ channel blocker SK&F96365, indicating that zymosan and PKC acti vate Ca2+ influx through a similar pathway. NR8383 AMs expressed one new PK C isoform (delta) and two atypical PKC isoforms (iota and lambda), but conv entional PKC isoforms were not present. Stimulation with zymosan resulted i n a translocation of PKC-delta from the cytosol to the membrane fraction. F urthermore, inhibition of protein tyrosine kinases (PTKs) with genistein pr evented zymosan-stimulated Ca2+ influx and PKC-delta translocation. These r esults suggest that PKC-delta plays a critical role in regulating (1-3)-bet a-glucan receptor activated Ca2+ influx in NR8383 AMs and PKC-delta translo cation is possibly dependent on PTK activity. (C) 2000 Wiley-Liss, Inc.