Modulation of cell death pathways to apoptosis and necrosis of H2O2-treated rat thymocytes by lipocortin I

Lipocortin I, also called annexin I, a calcium and phospholipid binding protein, protected rat thymocytes from H2O2-elicited necrosis and facilitated H2O2-induced apoptosis, while anti-lipocortin I antibody enhanced H2O2-elicited necrosis by blocking H2O2-induced apoptosis. Essentially similar results were obtained with phospholipase A(2) inhibitors and activators such as 3,4-octyadecyl-benzylacrylic acid and melittin, respectively. Available evidence suggests that lipocortin I modulates signals for cell death pathways of H2O2-treated rat thymocytes to apoptosis and necrosis by regulating cellular phospholipase A(2) activities but not by inhibiting membrane lipid peroxidation. (C) 1996 Academic Press, Inc.