15-LOX-catalytic bias towards ether-(alkenyl)-ETE-PEs oxidation bestows selectivity of PRO-ferroptotic cell death signaling.

Ether (alkyl/alkenyl) phospholipids, particularly phosphatidylethanolamine (PE) and phosphatidylcholine (PC), are broadly represented in membranes, but their physiological functions are poorly characterized. The antioxidant role of plasmalogens realized via oxidation of sn-1 vinyl bond has been associated with anti-ferroptotic regulatory function. Alternatively, peroxidation of polyunsaturated fatty acid (PUFA) in sn-2-position of alkenyl-PEs can be pro-ferroptotic. Since 15-LOXs generate 15-HpETE-PEs as ferroptotic signals, we explored alkyl/alkenyl-ETE-PE as substrates of enzymatic peroxidation. Using redox lipidomics, biochemical, biophysical, genetic approaches, and molecular dynamics simulations, we established that both isoforms of 15-LOX (15-LOX-1 and 15-LOX-2) selectively oxidize alkyl/alkenyl-ETE-PE (but not alkyl/alkenyl-ETE-PC), forming 15-HpETE-PEs, triggering ferroptotic death, independently of the vinyl bond. We showed that LOX-catalyzed peroxidation rate of sn-1 vinyl bond is ~500-fold lower than sn-2-ETE-PE, thus excluding the antioxidant role of plasmalogens in ferroptosis. We showed 15-LOX-driven production of sn-1-alkenyl-sn-2-15-HpETE-PE acts as pathogenic factor in acute/chronic diseases: asthma, cancer, brain trauma, skin UVB-injury. Thus, 15-LOX-catalyzed bias towards oxidation of alkenyl-ETE-PE may represent a new therapeutic target.