The adenine nucleotide translocator: a target of nitric oxide, peroxynitrite, and 4-hydroxynonenal

Nitric oxide (NO), peroxynitrite, and 4-hydroxynonenal (HNE) may be involve d in the pathological demise of cells via apoptosis, Apoptosis induced by t hese agents is inhibited by Bcl-2, suggesting the involvement of mitochondr ia in the death pathway. In vitro, NO, peroxynitrite and HNE can cause dire ct permeabilization of mitochondrial membranes, and this effect is inhibite d by cyclosporin A, indicating involvement of the permeability transition p ore complex (PTPC) in the permeabilization event. NO, peroxynitrite and HNE also permeabilize proteoliposomes containing the adenine nucleotide transl ocator (ANT), one of the key components of the PTPC, yet have no or little effects on protein-free control liposomes, ANT-dependent, NO-, peroxynitrit e- or HNE-induced permeabilization is at least partially inhibited by recom binant Bcl-2 protein, as well as the antioxidants trolox and butylated hydr oxytoluene, In vitro, none of the tested agents (NO, peroxynitrite, FINE, a nd tert-butylhydroperoxide) causes preferential carbonylation HNE adduction , or nitrotyrosylation of ANT. How ever, all these agents induced ANT to un dergo thiol oxidation/derivatization. Peroxynitrite and HNE also caused sig nificant lipid peroxidation, which was antagonized by butylated hydroxytolu ene but not by recombinant Bcl-2, Transfection-enforced expression of vMIA, a viral apoptosis inhibitor specifically targeted to ANT, largely reduces the mitochondrial and nuclear signs of apoptosis induced by NO, peroxynitri te and HNE in intact cells. Taken together these data suggest that NO, pero xynitrite, and HNE may directly act on ANT to induce mitochondrial membrane permeabilization and apoptosis.