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This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Gay, J. C. Articles by Stitt, E. S. Search for Related Content PubMed PubMed Citation Articles by Gay, J. C. Articles by Stitt, E. S. Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  Platelet-activating factor induces protein kinase activity in the particulate fraction of human neutrophils JC Gay and ES Stitt Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232. Platelet-activating factor (PAF) is a proinflammatory lipid that has both platelet- and phagocyte-stimulating properties. Because several known activators of calcium-, phospholipid-dependent protein kinase (protein kinase c, PKC) also stimulate neutrophil responses and because neutrophil stimuli such as phorbol diesters and the chemotactic peptide f-Met-Leu-Phe are reported to increase protein kinase activity in neutrophil (PMN) particulate fractions, we investigated the effect of PAF on neutrophil protein kinase activities. In neutrophils exposed to 10(-6) mol/L PAF, cytosolic PKC activity was 521 +/- 38 pmol 32P/10(7) PMN/min (mean +/- SEM), which was not significantly lower than cystolic activity in buffer-treated controls (558 +/- 32 pmol 32P/10(7) PMN/min, n = 14). PAF-exposed cells exhibited a concomitant rise in protein kinase activity associated with the particulate fraction with 53 +/- 4 pmol 32P/10(7) PMN/min compared with 32 +/- 2 pmol in control cells (n = 14). Particulate protein kinase activity was independent of the presence of calcium and phospholipid in the assay medium. The specific PKC inhibitor H-7 inhibited particulate protein kinase activity, however, which suggested that the enzyme activity assayed in this fraction may be PKC in a constitutively activated form. The increase in particulate protein kinase activity induced by PAF required the presence of cytochalasin B, was detectable within 5 seconds of exposure to PAF, and was not reversed by washing the cells free of extracellular PAF after initial exposure. Although PAF did not have a direct effect on PKC activity from cytosolic fractions from resting cells, the increase in particulate protein kinase activity induced by PAF was inhibited when the cells were first depleted of calcium by incubation with Quin 2. These results suggest that PAF induces an increase in particulate protein kinase activity in neutrophils by a calcium- dependent mechanism and that the induction of membrane-associated protein kinase activity may be involved in neutrophil-stimulating actions such as superoxide production, which occur at higher concentrations of PAF. Volume 71, Issue 1, pp. 159-165, 01/01/1988 Copyright © 1988 by The American Society of Hematology CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

	Copyright © 1988 by American Society of Hematology         Online ISSN: 1528-0020