Human cultured skin fibroblasts survive profound inherited ubiquinone depletion

Beside its role in electron transfer in the mitochondrial respiratory chain , ubiquinone is known to prevent lipid peroxidation and DNA damage by trapp ing cellular free radicals. Thanks to its antioxidant properties, ubiquinon e may represent an important factor controlling both necrotic and apoptotic processes. We have investigated the consequences of a profound inherited u biquinone depletion on cultured skin fibroblasts of a patient presenting wi th encephalomyopathy. Interestingly, cell respiration, mitochondrial oxidat ion of various substrates, and cell growth of ubiquinone-deficient fibrobla sts were only partially decreased. Moreover, these cells did not apparently overproduce superoxide anions or lipoperoxides. Finally, apoptosis did not increase as compared to control, even after serum deprivation. These obser vations suggest that ubiquinone may not play a major role in the antioxidan t defenses of cultured fibroblasts and that its role in controlling oxidati ve stress and apoptosis may greatly vary across cell types, especially as n ot all tissues were equally affected in the patient despite the widespread ubiquinone depletion in vivo.