Bcl-2 inhibits selective oxidation and externalization of
phosphatidylserine during paraquat-induced apoptosis.
Fabisiak, James P., Valerian E. Kagan, Vladimir B. Ritov, Daniel E.
Johnson, John S. Lazo.
Departments of Pharmacology, Medicine and Environmental &
Occupational Health, Schools of Medicine and Public Health,
University of Pittsburgh, Pittsburgh, PA 15261
APStracts 3:0287C, 1996.
Oxidative stress is a potential component of the final common pathway
leading to apoptosis following many diverse stimuli. Here we document
that the oxidant paraquat caused apoptosis in mouse 32D cells. We
examined early paraquat-induced lipid peroxidation after metabolic
incorporation of the oxidant-sensitive fluorescent fatty acid cis
-parinaric acid (cis-PA) into phospholipids and HPLC separation of
specific phospholipid classes. Paraquat induced peroxidation of cis
-PA primarily in phosphatidylserine (PS), and to a lesser extent
phosphatidylinositol (PI) within 2 hr. The selective oxidation of PS
occurred before signs of cytotoxicity and preceded the
externalization of PS as assessed by annexin V binding.
Overexpression of Bcl-2 afforded significant protection against
paraquat-induced apoptosis, early PS and PI oxidation, and PS
externalization, but not the ultimate formation of high molecular
weight DNA fragments. Therefore, both selective phospholipid
peroxidation and DNA damage occurred following paraquat exposure, but
only the former was specifically associated with apoptosis. We
suggest Bcl-2 may inhibit oxidant-induced apoptosis by preventing the
peroxidation of specific membrane phospholipids.
Received 22 July 1996; accepted in final form 3 September 1996.
APS Manuscript Number C406-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996