5-Hydroxyeicosatetraenoic acid is a key intermediate of the arachidonate-dependent protective signaling in monocytes/macrophages exposed to peroxynitrite.
Endogenous generation of arachidonic acid via selective activation of cytosolic phospholipase A(2) has been implicated in the mechanism of monocytes/macrophage survival in the presence of peroxynitrite. In particular, the lipid messenger was shown to prevent the otherwise rapid onset of a mitochondrial permeability-transition (MPT)-dependent necrosis by causing the mitochondrial translocation of protein kinase Calpha (PKCalpha) and the ensuing cytosolic accumulation of the Bcl-2-antagonist of cell death (Bad), an event promoting the anti-MPT function of Bcl-2 (or Bcl-X(L)). Here, we show that the effects on PKCalpha are not mediated directly by arachidonate but rather, by downstream products of the enzyme 5-lipoxygenase (5-LO). Peroxynitrite elicited the nuclear membrane translocation of 5-LO and enhanced its enzymatic activity via a mechanism sensitive to low concentrations of inhibitors of 5-LO or the 5-LO-activating protein, as well as to genetic depletion of the latter enzyme. Inhibition of 5-LO activity was invariably associated with the cytosolic localization of PKCalpha, the mitochondrial accumulation of Bad, and a rapid MPT-dependent necrosis. All these events were prevented by nanomolar concentrations of the 5-LO product 5-hydroxyeicosatetraenoic acid.
Tommasini
Ilaria
I
Università degli Studi di Urbino Carlo Bo, Urbino, Italy.
Guidarelli
Andrea
A
Palomba
Letizia
L
Cerioni
Liana
L
Cantoni
Orazio
O
D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism; D016718:Arachidonic Acid / Q000494:pharmacology / Q000502:physiology*; D016923:Cell Death / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology / Q000502:physiology*; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000276:immunology; D016859:Lipoxygenase Inhibitors; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology; D009637:Masoprocol / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000494:pharmacology*; D051571:Protein Kinase C-alpha / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D013329:Structure-Activity Relationship; D020298:U937 Cells
D004791:Enzyme Inhibitors; D006893:Hydroxyeicosatetraenoic Acids; D016859:Lipoxygenase Inhibitors; D030421:Peroxynitrous Acid; D016718:Arachidonic Acid; C022022:5-hydroxy-6,8,11,14-eicosatetraenoic acid; D009637:Masoprocol; D001094:Arachidonate 5-Lipoxygenase; D051571:Protein Kinase C-alpha