title: Reptilian uncoupling protein: functionality and expression in sub-zero temperatures.
abstract: Here we report the partial nucleotide sequence of a reptilian uncoupling protein (repUCP) gene from the European common lizard (Lacerta vivipara). Overlapping sequence analysis reveals that the protein shows 55%, 72% and 77% sequence homology with rat UCP1, UCP2 and UCP3, respectively, and 73% with bird and fish UCPs. RepUCP gene expression was ubiquitously detected in 4 degrees C cold-acclimated lizard tissues and upregulated in muscle tissues by a 20 h exposure to sub-zero temperatures in a supercooling state or after thawing. In parallel, we show an increase in the co-activators, peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha) and peroxisome proliferator-activated receptors (PPAR), mRNA expression, suggesting that the mechanisms regulating UCP expression may be conserved between mammals (endotherms) and reptiles (ectotherms). Furthermore, mitochondria extracted from lizard skeletal muscle showed a guanosine diphosphate (GDP)-sensitive non phosphorylating respiration. This last result indicates an inhibition of extra proton leakage mediated by an uncoupling protein, providing arguments that repUCP is functional in lizard tissues. This result is associated with a remarkable GDP-dependent increase in mitochondrial endogenous H(2)O(2) production. All together, these data support a physiological role of the repUCP in superoxide limitation by lizard mitochondria in situations of stressful oxidative reperfusion following a re-warming period in winter.
authors.affiliation: Laboratoire de Physiologie Intégrative, cellulaire et moléculaire, Centre National de la Recherche Scientifique (CNRS) - Université Claude Bernard Lyon 1, 43 Bvd 11 Novembre 1918, F-69622 Villeurbanne Cedex, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Rey
authors.forename: Brigitte
authors.initials: B
authors.lastname: Sibille
authors.forename: Caroline
authors.initials: C
authors.lastname: Romestaing
authors.forename: Maud
authors.initials: M
authors.lastname: Belouze
authors.forename: Dominique
authors.initials: D
authors.lastname: Letexier
authors.forename: Stéphane
authors.initials: S
authors.lastname: Servais
authors.forename: Hervé
authors.initials: H
authors.lastname: Barré
authors.forename: Claude
authors.initials: C
authors.lastname: Duchamp
authors.forename: Yann
authors.initials: Y
authors.lastname: Voituron
mesh_terms: D000595:Amino Acid Sequence; D000704:Analysis of Variance; D000818:Animals; D001483:Base Sequence; D003080:Cold Temperature; D005786:Gene Expression Regulation / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000378:metabolism; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism*; D008116:Lizards / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D047492:Peroxisome Proliferator-Activated Receptors / Q000378:metabolism; D030162:Reptilian Proteins / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D013045:Species Specificity; D000071256:Uncoupling Protein 1
chemical_list: D007473:Ion Channels; D024101:Mitochondrial Proteins; D047492:Peroxisome Proliferator-Activated Receptors; D030162:Reptilian Proteins; C000604373:Ucp1 protein, rat; D000071256:Uncoupling Protein 1; D006861:Hydrogen Peroxide