Spontaneous neutrophil apoptosis involves caspase 3-mediated activation of protein kinase C-δ

Judit Pongracz, Paul Webb, Keqing Wang, Elizabeth Deacon, Olivia J. Lunn, Janet M. Lord

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Abstract

Neutrophils are short-lived leukocytes that die by apoptosis. Whereas stress-induced apoptosis is mediated by the p38 mitogen-activated protein (MAP) kinase pathway (Frasch, S. C., Nick, J. A., Fadok, V. A., Bratton, D. L., Worthen, G. S., and Henson, P. M. (1998) J. Biol. Chem. 273, 8389-8397), signals regulating spontaneous neutrophil apoptosis have not been fully determined. In this study we found increased activation of protein kinase C (PKC)-β and -δ in neutrophils undergoing spontaneous apoptosis, but we show that only activation of PKC-δ was directly involved in the induction of apoptosis. PKC-δ can be proteolytically activated by caspase 3. We detected the 40-kDa caspase-generated fragment of PKC-δ in apoptotic neutrophils and showed that the caspase 3 inhibitor Asp-Glu-Val-Asp-fluoromethylketone prevented generation of the 40-kDa PKC-δ fragment and delayed neutrophil apoptosis. In a cell-free system, removal of PKC-δ by immunoprecipitation reduced DNA fragmentation, whereas loss of PKC-α, -β, or -ζ had no significant effect. Rottlerin and LY379196 inhibit PKC-δ and PKC-β, respectively. Only Rottlerin was able to delay neutrophil apoptosis. Inhibitors of MAP-ERK kinase 1 (PD98059) or p38 MAP kinase (SB202190) had no effect on neutrophil apoptosis, and activation of p42/44 and p38 MAP kinase did not increase in apoptotic neutrophils. We conclude that spontaneous neutrophil apoptosis involves activation of PKC-δ but is MAP kinase- independent.

Original languageEnglish
Pages (from-to)37329-37334
Number of pages6
JournalJournal of Biological Chemistry
Volume274
Issue number52
DOIs
Publication statusPublished - Dec 24 1999

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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