title: Absence of uncoupling protein-3 leads to greater activation of an adenine nucleotide translocase-mediated proton conductance in skeletal muscle mitochondria from calorie restricted mice.
abstract: Calorie restriction (CR), without malnutrition, consistently increases lifespan in all species tested, and reduces age-associated pathologies in mammals. Alterations in mitochondrial content and function are thought to underlie some of the effects of CR. Previously, we reported that rats subjected to variable durations of 40% CR demonstrated a rapid and sustained decrease in maximal leak-dependent respiration in skeletal muscle mitochondria. This was accompanied by decreased mitochondrial reactive oxygen species generation and increased uncoupling protein-3 protein (UCP3) expression. The aim of the present study was to determine the contribution of UCP3, as well as the adenine nucleotide translocase to these functional changes in skeletal muscle mitochondria. Consistent with previous findings in rats, short-term CR (2 weeks) in wild-type (Wt) mice resulted in a lowering of the maximal leak-dependent respiration in skeletal muscle mitochondria, without any change in proton conductance. In contrast, skeletal muscle mitochondria from Ucp3-knockout (KO) mice similarly subjected to short-term CR showed no change in maximal leak-dependent respiration, but displayed an increased proton conductance. Determination of ANT activity (by measurement of inhibitor-sensitive leak) and protein expression revealed that the increased proton conductance in mitochondria from CR Ucp3-KO mice could be entirely attributed to a greater acute activation of ANT. These observations implicate UCP3 in CR-induced mitochondrial remodeling. Specifically, they imply the potential for an interaction, or some degree of functional redundancy, between UCP3 and ANT, and also suggest that UCP3 can minimize the induction of the ANT-mediated 'energy-wasting' process during CR.
authors.affiliation: Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada KIH 8M5.
authors.forename: Lisa
authors.initials: L
authors.lastname: Bevilacqua
authors.forename: Erin L
authors.initials: EL
authors.lastname: Seifert
authors.forename: Carmen
authors.initials: C
authors.lastname: Estey
authors.forename: Martin F
authors.initials: MF
authors.lastname: Gerrits
authors.forename: Mary-Ellen
authors.initials: ME
authors.lastname: Harper
mesh_terms: D000818:Animals; D031204:Caloric Restriction; D004734:Energy Metabolism; D007473:Ion Channels / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008931:Mitochondria, Muscle / Q000378:metabolism*; D000226:Mitochondrial ADP, ATP Translocases / Q000502:physiology*; D024101:Mitochondrial Proteins / Q000502:physiology*; D009929:Organ Size; D017382:Reactive Oxygen Species / Q000378:metabolism; D000071247:Uncoupling Protein 3
chemical_list: D007473:Ion Channels; D024101:Mitochondrial Proteins; D017382:Reactive Oxygen Species; C000604393:Ucp3 protein, mouse; C000604394:Ucp3 protein, rat; D000071247:Uncoupling Protein 3; D000226:Mitochondrial ADP, ATP Translocases