Reactive oxygen species and NO-derived oxidizing, nitrosating and nitrating products mediate diverse cell signaling and pathologic processes in cardiovascular, pulmonary, and neurodegenerative diseases (1, 2). These reactive inflammatory mediators chemically modify carbohydrates, DNA bases, amino acids, and unsaturated fatty acids to form oxidized, nitrosated and nitrated derivatives. For example, accumulation of inflammatory-induced protein tyrosine nitration products represents a shift from the physiological signal-transducing actions of NO to an oxidative, nitrative, and potentially pathogenic pathway (1).Recently, it has been reported that nitration products of unsaturated fatty acids (nitroalkenes) are formed via NO-dependent oxidative reactions (3-5). These derivatives were initially viewed to be, like nitrotyrosine, a "footprint" of NO-dependent redox reactions (3, 6). More recently, we have observed that nitrolinoleate (LNO 2 ) 7 mediates pluripotent cell signaling actions, since it induces relaxation of phenylephrine-preconstricted rat aortic rings, inhibits thrombin-induced Ca 2ϩ elevations and aggregation of human platelets, and attenuates human neutrophil superoxide generation, degranulation, and integrin expression. These cell responses are mediated by both cGMP-and cAMP-dependent and -independent mechanisms (7-9).LNO 2 positional isomers, including 9-, 10-, 12-, and 13-nitro-9,12-cis-octadecadienoic acids, have been identified as free acids in human plasma and red blood cells and as esterified components of plasma lipoproteins and red blood cell membranes (10). In addition, plasma and red cell free and esterified nitrooleate (OA-NO 2 , isomers 9-and 10-nitro-9-cis-octadecenoic acid) was also identified in healthy human blood (11).Current knowledge indicates that enzymatically oxidized unsaturated fatty acid-derived products, such as prostaglandins, thromboxanes, leukotrienes, epoxyeicosatrienoic acids, hydroxyeicosatetraenoic acids, lipoxins, and resolvins serve as lipid mediators or autacoids. These signaling mediators act within a local microenvironment to orchestrate both physiological and pathological events, including platelet aggregation, constriction of vascular smooth muscle, neonatal development, wound healing, and resolution of inflammation (12, 13). In this context, endogenous nitrated fatty acid derivatives, such as * This work was supported by National Institutes of Health Grants HL068878, HL075397, and S06GM08248 (to Y. E. C.), HL70146 (to R. P. P.), and HL58115 and HL64937 (to B. A. F.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. □ S The on-line version of this article (available at http://www.jbc.org) contains supplemental Table S1, Fig. 1, and Movie 1. 1 Supported by American Diabetes Association Grant JFA 7-05-JF-12. 2 These authors contributed equally to this work. 3 Supported by the postdoctoral f...
