ACTIVATION OF MITOGEN-ACTIVATED PROTEIN-KINASE BY ARACHIDONIC-ACID IN RAT-LIVER EPITHELIAL WB CELLS BY A PROTEIN-KINASE C-DEPENDENT MECHANISM

被引:102
作者
HII, CST
FERRANTE, A
EDWARDS, YS
HUANG, ZH
HARTFIELD, PJ
RATHJEN, DA
POULOS, A
MURRAY, AW
机构
[1] WOMENS & CHILDRENS HOSP,DEPT CHEM PATHOL,ADELAIDE,SA 5006,AUSTRALIA
[2] FLINDERS UNIV S AUSTRALIA,SCH BIOL SCI,BEDFORD PK,SA 5042,AUSTRALIA
关键词
D O I
10.1074/jbc.270.9.4201
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Arachidonic acid (20:4(n-6)), which is released by cells responding to a wide range of stimuli, may play an important role in intracellular signaling. We now report that incubation of WB cells with 20:4(n-6) resulted in the appearance of several tyrosine-phosphorylated cytosolic proteins. Two of the phosphotyrosine-containing proteins, migrating in SDS-polyacrylamide gels of approximately 43 and 45 kDa, corresponded in mobility to phosphorylated species of the 42- and 44-kDa mitogen-activated protein kinase (MAPK) isoforms. Immunoblots of soluble fractions from unstimulated WR cells with anti-MAPK antibodies revealed the presence of the 42- and 44 kDa isoforms of MAPK. Upon incubation with 20:4(n-6), the mobility of both isoforms was retarded, consistent with their activation by phosphorylation. Chromatography of soluble fractions from these cells on Mono Q columns revealed early and late eluting peaks of myelin basic protein kinase activity, which contained the 42- and 44-kDa MAPK isoforms, respectively. Activation of MAPK was transient, peaking at 5 min, and was detectable at 5 mu M 20:4(n-6). Further studies into the mechanisms by which MAPK was activated by 20:4(n-6) strongly suggested the involvement of protein kinase C (PRC). Not only did incubation of WB cells with 20:4(n-6) result in the translocation of PKC alpha, delta, and epsilon to a particulate fraction, it was found that the fatty acid failed to activate MAPK in cells pretreated for 26 h with phorbol la myristate 13-acetate, which depleted WE cells of PKC alpha, delta, and epsilon. In addition, fatty acids of the n-3 series were effective activators of MAPK. The present study, to our knowledge, is the first to report that polyunsaturated fatty acids can cause the activation of MAPK.
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页码:4201 / 4204
页数:4
相关论文
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