Avian uncoupling protein expressed in yeast mitochondria prevents endogenous free radical damage.
The longevity of birds is surprising since they exhibit high metabolic rates and elevated blood sugar levels compared with mammals of the same body size, which presumably expose them to higher rates of free oxygen radical production, which is implicated in accelerated senescence. Uncoupling proteins (UCPs) are transporters of the inner mitochondrial membrane and their physiological activity is still a subject of debate. Avian UCP was found in birds but data on its activity are scarce. Avian UCP (Gallus gallus) was overexpressed in yeast and we assessed its ability to prevent mitochondrial reactive oxygen species (ROS) production by measuring ROS damage (aconitase activity) and antioxidant defences (MnSOD activity). We show that avian UCP protects yeast mitochondria against the deleterious impact of ROS, but without stimulation of superoxide dismutase activity. Avian UCP protein was specifically immunodetected and retinoic acid, which belongs to the carotenoid family, was found to trigger its activity. These data show that avian UCP basal activity protects against ROS damage. However, when activated by retinoic acid, avian UCP can also operate as the mammalian thermogenic UCP1. The hypothesis that avian UCP activities are state- and species-dependent is further discussed.
Criscuolo
François
F
Faculté de Médecine Necker-Enfants Malades, CNRS-UPR 9078, 156 rue de Vaugirard, 75730 Paris Cedex 15, France. criscuolo@wanadoo.fr
Gonzalez-Barroso
Maria del Mar
Mdel M
Le Maho
Yvon
Y
Ricquier
Daniel
D
Bouillaud
Frederic
F
D000154:Aconitate Hydratase / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D030161:Avian Proteins / Q000235:genetics / Q000378:metabolism*; D002645:Chickens / Q000235:genetics*; D005609:Free Radicals / Q000378:metabolism*; D005649:Fumarate Hydratase / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D000071245:Mitochondrial Uncoupling Proteins; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D014212:Tretinoin / Q000378:metabolism
D030161:Avian Proteins; D005609:Free Radicals; D024101:Mitochondrial Proteins; D000071245:Mitochondrial Uncoupling Proteins; D017382:Reactive Oxygen Species; C422907:mitochondrial uncoupling protein, chicken; D014212:Tretinoin; D013482:Superoxide Dismutase; D005649:Fumarate Hydratase; D000154:Aconitate Hydratase