Recycling of dysfunctional mitochondria in coenzyme Q deficiency

Resumen del póster presentado al 22nd IUBMB & 37th FEBS Congress, celebrado en Sevilla (España) del 4 al 9 de septiembre de 2012.Coenzyme Q10(CoQ) is a unique redox lipid that transports electrons from complexes I and II to complex III in the mitochondrial respiratory chain. In addition, CoQ is a key component of the antioxidant system in all intracellular membranes, being the only endogenously synthesized lipid soluble antioxidant (Betinger M, et al 2007). CoQ deficiency is a rare human genetic condition that has been associated with an increasing number of clinical phenotypes including encephalomiopathy and renal syndromes (Quinzii M, et al. 2011). CoQ deficiency may be associated to mutations in genes directly involved in CoQ biosynthesis (primary deficiency) or in other genes unrelated to the biosynthetic pathway as well as non genetics factors (secondary deficiencies) (Trevisson E, et al. 2011). In order to elucidate how CoQ deficiency affects an organism, we have investigated the pathophysiologic processes present within fibroblasts derived from patients with this syndrome. Assays of cultured fibroblasts revealed a large group of alterations, with affection of the OX-PHOS activity, increased production of reactive oxygen species (ROS) and activation of mitochondrial permeability transition (MPT). These abnormalities triggered a mitochondrial degradation process by autophagy (mitophagy) detected by enhanced expression of autophagy genes and presence of autophagosomes containing abnormal mitochondria. Autophagy in CoQ-deficient fibroblasts affected only mitochondria but not other organelles, and was partially abolished by either antioxidants or cyclosporine treatments suggesting that both ROS and MPT participate in this process. Furthermore, prevention of autophagy in this model resulted in apoptotic cell death, suggesting a protective role of autophagy in CoQ deficient fibroblasts.Peer reviewe