Pioglitazone Ameliorates Mitochondrial Oxidative Stress and Inflammation via AMPK-Dependent Inhibition of Mitochondrial Fission in Leigh Syndrome.

Abstract

Loss of function mutations of NDUFS4 resulted in Leigh syndrome, which is a progressive neurodegenerative disease and characterized by mitochondrial oxidative stress, inflammation and aberrant mitochondrial dynamics. However, there is currently no effective treatment. Here, we demonstrate that pioglitazone significantly mitigates mitochondrial reactive oxygen species (ROS) generation, lowers cyclooxygenase-2 (COX-2) mRNA levels, and rescues aberrant mitochondrial dynamics in vitro (increasing Opa-1 expression while decreasing Drp-1 expression). Furthermore, similar effects were observed with the selective Drp-1 inhibitor mdivi-1, suggesting that inhibiting mitochondrial fission mediates the therapeutic effects of pioglitazone. Pioglitazone administration activated AMPK phosphorylation, but these effects, along with pioglitazone's ability to reverse oxidative stress, inflammation, and mitochondrial fission, were abolished by the AMPK inhibitor compound C. In vivo, pioglitazone alleviated motor dysfunction, prolonged lifespan, and promoted weight gain in Ndufs4 KO mice. This was accompanied by enhanced mitochondrial fusion and increased levels of mitochondrial complex subunits. Consistently, pioglitazone attenuated neuroinflammation and oxidative stress in vivo. Collectively, our findings indicate that pioglitazone alleviates mitochondrial oxidative stress and inflammation through an AMPK-dependent inhibition of Drp-1-mediated mitochondrial fission. Therefore, suppression of mitochondrial fission may represent a novel therapeutic strategy for Leigh syndrome (LS).