Bromophenacyl bromide binding to the actin-bundling protein l-plastin inhibits inositol trisphosphate-independent increase in Ca2+ in human neutrophils
Por:
Rosales C., Jones S.L., McCourt D., Brown E.J.
Publicada:
1 ene 1994
Resumen:
Ligation of IgG Fc receptors on polymorphonuclear leukocytes causes an increase in the concentration of free intracytoplasmic Ca2+ ([Ca2+]i) which arises from release of intracellular stores but is independent of inositol 1,4,5-trisphosphate. We found that bromophenacyl bromide (BPB), an alkylating agent which inhibits leukocyte degranulation, adherence, and phagocytosis, inhibited IgG-stimulated increases in [Ca2+]i with an IC50 Of 0.2 ?M. In contrast, BPB had no effect on inositol 1,4,5-trisphosphate-dependent [Ca2+]i increases induced by fMet-Leu-Phe, complement fragment CSa, ATP, or platelet-activating factor. Using a monoclonal antibody specific for BPB, we identified in polymorphonuclear leukocytes a single cytosolic protein of 66 kDa and isoelectric point pH 5.6 which bound BPB when intact cells were treated with the alkylating agent. This BPB-binding protein was identified as l-plastin, a Ca2+-regulated actin-bundling protein. l-Plastin was found associated with the Triton X-100-insoluble cytoskeleton in polymorphonuclear leukocytes adherent to immune complexes, suggesting that BPB affects Fc receptormediated signal transduction by altering the actin cytoskeleton. Consistent with this hypothesis, both cytochalasin B and cytochalasin D inhibited the IgG-dependent increase in [Ca2+]i, without any effect on fMet-Leu-Phe-induced Ca2+ release. These data suggest that the actin cytoskeleton is essential for signal transduction from plasma membrane Fc receptors and that l-plastin has a critical role in activation of this pathway.
Filiaciones:
Rosales C.:
Washington Univ. School of Medicine, Campus Box 8051, 660 South Euclid Avenue, St. Louis, MO 63110, United States
Jones S.L.:
Washington Univ. School of Medicine, Campus Box 8051, 660 South Euclid Avenue, St. Louis, MO 63110, United States
McCourt D.:
Washington Univ. School of Medicine, Campus Box 8051, 660 South Euclid Avenue, St. Louis, MO 63110, United States
Brown E.J.:
Washington Univ. School of Medicine, Campus Box 8051, 660 South Euclid Avenue, St. Louis, MO 63110, United States
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