Annexin-I inhibits PMA-induced c-fos SRE activation by suppressing cytosolic phospholipase A2 signal.
Annexin-I (ANX-I) is a 37-kDa protein with a calcium-dependent phospholipid-binding property. Previously we have observed the inhibition of cytosolic phospholipase A2 (cPLA2) by ANX-I in the studies using purified recombinant ANX-I, and proposed a specific interaction model for the mechanism of cPLA2 inhibition by ANX-I [Kim et al. (1994) FEBS Lett. 343, 251-255]. Here we have studied the role of ANX-I in the cPLA2 signaling pathway by transient transfection assay. The stimulation of Rat2 fibroblast cells with phorbol 12-myristate 13-acetate (PMA) induced the c-fos serum response element (SRE). The SRE stimulation by PMA was dramatically reduced by (1) pretreatment with a cPLA2-specific inhibitor, arachidonyltrifluoromethyl ketone, or (2) co-transfection with antisense cPLA2 oligonucleotide, indicating that the SRE activation was through cPLA2 activation. Co-transfection with an ANX-I expression vector also reduced the SRE stimulation by PMA, suggesting the inhibition of cPLA2 by ANX-I. The active domain of ANX-I was mapped using various deletion mutants. ANX-I(1-113) and ANX-I(34-346) were fully active, whereas ANX-I(114-346) abolished the activity. Therefore the activity was in the amino acid 34 to 113 region, which corresponds to the conserved domain I of ANX-I.
Oh
J
J
Department of Biochemistry, College of Medicine, University of Ulsan, 388-1 Poongnap-dong, Songpa-ku, Seoul, South Korea.
Rhee
H J
HJ
Kim
S
S
Kim
S B
SB
You
H
H
Kim
J H
JH
Na
D S
DS
D000818:Animals; D017305:Annexin A1 / Q000494:pharmacology*; D001483:Base Sequence; D002460:Cell Line; D003600:Cytosol / Q000187:drug effects* / Q000201:enzymology; D016762:Genes, fos; D009841:Oligonucleotides; D010741:Phospholipases A / Q000037:antagonists & inhibitors* / Q000378:metabolism; D054467:Phospholipases A2; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D017305:Annexin A1; D009841:Oligonucleotides; D010741:Phospholipases A; D054467:Phospholipases A2; D013755:Tetradecanoylphorbol Acetate