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Regulation of phospholipase A 2 activation and arachidonic acid metabolism in an interleukin‐3–dependent macrophage‐like cell line
Author(s) -
Shibata Yoshimi,
McCaffrey Patricia G.,
Minowada Jun,
Volkman Alvin,
Oghiso Yoichi
Publication year - 1992
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.51.1.32
Subject(s) - phospholipase a2 , cytosol , arachidonic acid , biology , protein kinase c , eicosanoid metabolism , phorbol , phospholipase a , leukotriene , cell culture , eicosanoid , biochemistry , phospholipase , leukotriene c4 , microbiology and biotechnology , enzyme , immunology , genetics , asthma
An interleukin 3 (IL‐3)–dependent macrophage‐like cell line, 11‐1‐B3, was newly established from CBA/J mouse bone marrow cell cultures. Assay of eicosanoids in the culture supernatants of the intact and [ 3 H]arachidonic acid (AA)–prelabeled cells showed that, after stimulation with the Ca 2+ ionophore A23187, the 11‐1‐B3 cells synthesized and released relatively large amounts of prostaglandin E 2 (PGE 2 ) and leukotriene B 4 (LTB 4 ) but not LTC 4 . In addition, 11‐1‐B3 cells showed Ca 2+ ‐dependent and alkaline pH–optimal phospholipase A 2 (PLA 2 ) activity that preferentially hydrolyzed cleavage of sn ‐2‐arachidonyl‐ but not sn ‐2‐oleoylphosphatidylcholine. The cellular enzyme was distributed with 90% of the activity in the cytosol and 10% in the membrane fraction. Treatment of cells with A23187 for 5–10 min resulted in five‐ to sevenfold increases in the membrane‐associated PLA 2 but activity in the cytosol was unchanged. This increase in membrane‐associated enzyme activity was transient, returning to the pretreatment distribution after 30 min. In sharp contrast, phorbol myristate acetate (PMA) stimulation failed to induce either eicosanoid release or PLA 2 activation, although PMA induced translocation of protein kinase C (PKC) to the membrane fraction within 10 min. The data suggest that increases in cellular Ca 2+ directly activate membrane‐associated PLA 2 and consequently initiate AA metabolism; PKC activation by PMA requires additional steps to activate PLA 2 , a mechanism that is apparently deficient in the IL‐3–dependent Mø‐like cells.