In vitro evidence of inhibition of mitochondrial protease processing by HIV-1 protease inhibitors in yeast: a possible contribution to lipodystrophy syndrome.

Highly active antiretroviral therapy has been associated with the emergence of lipodystrophy syndromes that have clinical features commonly seen in patients with mitochondrial dysfunction. The effect of therapeutic protease inhibitors (PIs) on mitochondrial function is unknown. Mitochondrial matrix space proteins possess an amino-terminal leader peptide that is removed by the mitochondrial processing protease (MPP). Lack of cleavage could result in non- or dysfunctional mitochondrial proteins. The effects of different PIs on protease processing using pure MPP or yeast mitochondria, recognized models for mammalian counterparts, were examined in vitro. Multiple PIs were found to inhibit MPP, evidenced by accumulation of immature pALDH and decreased levels of processed ALDH. Both indinavir and amprenavir at 5.0 mg/ml resulted in significant inhibition of MPP. Although inhibition of MPP was also observed with ritonavir and saquinavir, the inhibition was difficult to quantify due to background inhibition of MPP by DMSO that was required to solubilize the drugs for the in vitro studies. Indinavir was also shown to inhibit MPP within yeast mitochondria. Lack of processing may impair mitochondrial function and contribute to the observed mitochondrial dysfunctions in patients receiving HAART and implicated in antiretroviral-associated lipodystrophy.