The mitochondrial respiratory complex I is a target for 15 - deoxy - 12 , 14 - prostaglandin J 2 action

The prostaglandin J 2 derivative 15-deoxy12,14 prostaglandin J 2 (15d-PGJ 2 ) is a very active compound with important effects on inflammation, apoptosis, and cell growth processes. To exert this broad range of effects, 15dPGJ 2 binds and alters the activity of diverse proteins, which consequently are postulated to be mediators of its action. Among them are the transcription factors peroxisome proliferator-activated receptor and nuclear factor B, which are thought to play an essential role in the antitumorigenic and anti-inflammatory actions of 15d-PGJ 2 . Here, we show that 15d-PGJ 2 , at micromolar concentrations, efficiently blocks state 3 oxygen consumption in intact nonsynaptic mitochondria isolated from rat cerebral cortex. This effect is attributable to the inhibition by this prostaglandin of the activity of the enzyme NADH-ubiquinone reductase (complex I) of the mitochondrial respiratory chain. In addition to this, 15d-PGJ 2 dramatically increases the rate of reactive oxygen species generation by complex I. The inhibition by 15d-PGJ 2 of complex I activity was abolished by dithiothreitol, which raises the possibility that adduct formation with a critical component of complex I accounts for the inhibitory effect of this prostaglandin. These results clearly identified mitochondrial complex I as a new target for 15d-PGJ 2 actions. —Martínez, B., A. Pérez-Castillo, and A. Santos. The mitochondrial respiratory complex I is a target for 15deoxy12,14 -prostaglandin J 2 action. J. Lipid Res. 2005. 46: 736–743. Supplementary key words respiratory chain • reactive oxygen species • cyclopentenone prostaglandins Prostaglandin J 2 (PGJ 2 ) and its metabolites 12 -PGJ 2 and 15-deoxy12,14 -PGJ 2 (15d-PGJ 2 ) are naturally occurring derivatives of prostaglandin D 2 , the most abundant prostaglandin in normal tissues (1). They have been shown to exert important effects on diverse biological processes, such as inflammation, cell growth, and apoptosis, with 15d-PGJ 2 as the most active component of this group of cyclopentenone prostaglandins (2, 3). Multiple mechanisms have been proposed to explain the diversity of action of 15d-PGJ 2 , although the relative importance of each of them is not completely established. 15d-PGJ 2 is the most active natural ligand of the peroxisome proliferator-activated receptor (PPAR ) (4, 5). PPAR is a transcription factor that belongs to the superfamily of nuclear receptors and therefore regulates gene expression in a ligand-dependent manner (6, 7). In addition to 15d-PGJ 2 , many other compounds have been shown to activate PPAR . Among them are the antidiabetic drugs thiazolidinedione and the nonsteroidal anti-inflammatory drugs (2). It is believed that PPAR mediates, at least in part, the actions of 15d-PGJ 2 on cell growth and apoptosis through the regulation by this transcription factor of the expression of genes critical to these processes, such as cyclin D1 and D2 (8, 9), cyclin-kinase inhibitors p21 warf1/cip1 and p27 kip1 (8, 10), tumor suppressors phosphatase and tensisn homologue deleted from chromosoma 10 (PTEN) and breast cancer susceptibility gene 1 (BRCA1) (11, 12), and bcl2 family members (13, 14). The transcription factor nuclear factor B (NFB) is another important target for 15d-PGJ 2 action. In the unstimulated state, NFB is sequestered in the cytosol by the repressor protein inhibitor B (IB) and consequently inactive. Upon cellular signaling, IB is phosphorylated by IB kinase, resulting in the degradation of IB and the translocation of NFB to the nucleus, where it regulates, among other functions, the expression of genes implicated in inflammatory processes (15). 15d-PGJ 2 inhibits NFB action by blocking IB kinase activity and NFB binding to DNA (16, 17). NFB inhibition by 15d-PGJ 2 is thought to represent the major pathway in the anti-inflammatory effects of this prostaglandin. In addition to PPAR Abbreviations: DCFH, dichlorofluorescin; 15d-PGJ 2 , 15-deoxy12,14 prostaglandin J 2 ; IB, inhibitor B; NFB, nuclear factor B; PGJ 2 , prostaglandin J 2 ; PPAR , peroxisome proliferator-activated receptor ; ROS, reactive oxygen species. 1 To whom correspondence should be addressed. e-mail: [email protected] (A.S.); [email protected] (A.P-C.) Manuscript received 7 October 2004 and in revised form 21 December 2004. Published, JLR Papers in Press, January 16, 2005. DOI 10.1194/jlr.M400392-JLR200 at P E N N S T A T E U N IV E R S IT Y , on F ebuary 0, 2013 w w w .j.org D ow nladed fom