Mitochondrial peroxiredoxin-3 is selectively oxidised in cells treated with pro-apoptotic isothiocyanates Free

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The isothiocyanates are a class of natural products derived from cruciferous vegetables. We have shown that aromatic isothiocyanates, in particular phenethyl isothiocyanate, possess an ability to induce apoptosis in cells that overexpress the anti-apoptotic protein Bcl-2. Many isothiocyanates, including sulforaphane, were unable to induce apoptosis in the cells expressing Bcl-2, despite sharing other biological properties. In this study we focussed on identification of the cellular targets of the pro-apoptotic isothiocyanates that may play a role in mediating apoptosis. The predominant intracellular reaction of the isothiocyanates is with cysteine residues, therefore, using a sensitive proteomic technique to label oxidised thiol proteins a preliminary investigation of the targets of the pro-apoptotic isothiocyanates was undertaken. We have shown that a selective pool of thiol proteins are modified following exposure to phenethyl isothiocyanate, but are not affected by exposure to sulforaphane. One thiol protein that consistently changed when cells were exposed to phenethyl isothiocyanate was identified as mitochondrial peroxiredoxin-3. The oxidation of peroxiredoxin-3 was validated by western blotting and shown to occur before the activation of apoptosis. This effect may bypass the anti-apoptotic action of Bcl-2 and promote apoptosis.