Hydrogen peroxide-induced c-fos expression is mediated by arachidonic acid release: role of protein kinase C.
We found previously that stimulation of c-fos and c-myc mRNA expression are early events in hydrogen peroxide-induced growth in rat aortic smooth muscle (RASM) cells. In the present study, we investigated the role of phospholipase A2 (PLA2) and protein kinase C (PKC) in mediating hydrogen peroxide-induced c-fos mRNA expression in RASM cells. Mepacrine and p-bromophenacylbromide, potent inhibitors of PLA2 activity, blocked hydrogen peroxide-induced c-fos mRNA expression. Arachidonic acid, a product of PLA2 activity, stimulated the expression of c-fos mRNA with a time course similar to that of hydrogen peroxide. PKC down-regulation attenuated both hydrogen peroxide and arachidonic acid-induced c-fos mRNA expression by 50%. Nordihydroguaiaretic acid (a lipoxygenase-cytochrome P450 monooxygenase inhibitor) significantly inhibited both hydrogen peroxide and arachidonic acid-induced c-fos mRNA expression, whereas indomethacin (a cyclooxygenase inhibitor) had no effect. Together, these findings indicate that 1) hydrogen peroxide-induced c-fos mRNA expression is mediated by PLA2-dependent arachidonic acid release, 2) both PKC-dependent and independent mechanisms are involved in hydrogen peroxide-induced expression of c-fos mRNA and 3) arachidonic acid metabolism via the lipoxygenase-cytochrome P450 monooxygenase pathway appears to be required for hydrogen peroxide-induced expression of c-fos mRNA.
Rao
G N
GN
Cardiology Division, Emory University School of Medicine, Atlanta, GA 30322.
Lasségue
B
B
Griendling
K K
KK
Alexander
R W
RW
Berk
B C
BC
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D015152:Blotting, Northern; D002478:Cells, Cultured; D015870:Gene Expression / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009637:Masoprocol / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics* / Q000378:metabolism; D011796:Quinacrine / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley
D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D016718:Arachidonic Acid; D009637:Masoprocol; D006861:Hydrogen Peroxide; D011493:Protein Kinase C; D011796:Quinacrine; D007213:Indomethacin