Qiu Z H, Leslie C C
Department of Pediatrics, National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado 80206.
J Biol Chem. 1994 Jul 29;269(30):19480-7.
The activation of mitogen-activated protein kinase (MAP kinase) in macrophages and the involvement of protein kinase C (PKC) in MAP kinase activation was investigated in macrophages exposed to agents that have previously been shown to activate the 85-kDa cytosolic phospholipase A2 (PLA2) and induce arachidonic acid release. Phorbol 12-myristate 13-acetate (PMA) and zymosan maximally stimulated MAP kinase activity by 5 and 15 min, respectively, whereas the response to okadaic acid was maximal by 60-90 min. MAP kinase activation correlated with tyrosine phosphorylation of p44 MAP kinase in PMA-stimulated cells and p44 and p42 MAP kinases in zymosan- and okadaic acid-stimulated cells. MAP kinase activity was not elevated in A23187-stimulated macrophages. Inhibition of PKC with the inhibitor, bisindolylmaleimide (GF109203X), or by prolonged exposure to PMA suppressed both arachidonic acid release and MAP kinase activation in PMA- and zymosan-stimulated macrophages but not in okadaic acid or A23187-treated cells. However, prolonged exposure to PMA did not suppress the increased cytosolic PLA2 activity in agonist-treated macrophages. This approach was complicated since initial exposure to PMA to down-regulate PKC increased cytosolic PLA2 activity which remained elevated for 16 h. In contrast, GF109203X treatment suppressed the increase in cytosolic PLA2 activity in response to zymosan and PMA but not to okadaic acid or A23187. The results demonstrate that PMA and zymosan trigger PKC activation that leads to the activation of MAP kinase and PLA2, whereas these responses are PKC independent in okadaic acid-treated cells. In addition, the results are consistent with a role for MAP kinase activation in regulating the activation of the 85-kDa PLA2 and arachidonic acid release in PMA-, zymosan-, and okadaic acid-stimulated cells, whereas these responses in A23187-treated cells are MAP kinase-and PKC-independent.
在暴露于先前已证明可激活85 kDa胞质磷脂酶A2（PLA2）并诱导花生四烯酸释放的试剂的巨噬细胞中，研究了丝裂原活化蛋白激酶（MAP激酶）的激活以及蛋白激酶C（PKC）在MAP激酶激活中的作用。佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）和酵母聚糖分别在5分钟和15分钟时最大程度地刺激MAP激酶活性，而对冈田酸的反应在60 - 90分钟时达到最大。在PMA刺激的细胞中，MAP激酶激活与p44 MAP激酶的酪氨酸磷酸化相关，在酵母聚糖和冈田酸刺激的细胞中与p44和p42 MAP激酶的酪氨酸磷酸化相关。在A23187刺激的巨噬细胞中，MAP激酶活性未升高。用抑制剂双吲哚马来酰亚胺（GF109203X）抑制PKC，或长时间暴露于PMA，可抑制PMA和酵母聚糖刺激的巨噬细胞中花生四烯酸的释放和MAP激酶的激活，但对冈田酸或A23187处理的细胞无此作用。然而，长时间暴露于PMA并未抑制激动剂处理的巨噬细胞中胞质PLA2活性的增加。这种方法很复杂，因为最初暴露于PMA以下调PKC会增加胞质PLA2活性，该活性会持续升高16小时。相反，GF109203X处理可抑制酵母聚糖和PMA刺激引起的胞质PLA2活性增加，但对冈田酸或A23187刺激无此作用。结果表明，PMA和酵母聚糖触发PKC激活，进而导致MAP激酶和PLA2的激活，而在冈田酸处理的细胞中，这些反应不依赖于PKC。此外，结果表明MAP激酶激活在调节PMA、酵母聚糖和冈田酸刺激的细胞中85 kDa PLA2的激活和花生四烯酸释放中起作用，而在A23187处理的细胞中，这些反应不依赖于MAP激酶和PKC。
