Potential implication of mitochondrial fusion proteins in the ontogeny of muscle bioenergetics in birds

• Main Author: Fongy, Anaïs
• Other Authors: Physiologie intégrative, cellulaire et moléculaire (PICM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Centre National de la Recherche Scientifique (CNRS), Université Claude Bernard - Lyon I, Claude Duchamp, Caroline Romestaing
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2013
• Subjects: Adélie penguins; Ducklings; Mitochondrial activity; Permeabilized fibers; Energetic constraints; Thyroid hormones; Birds; Manchots Adélie; Canetons; Bioénergétique mitochondriale; Fibres perméabilisées; OPA1; Mfn2; Contraintes énergétiques; Hormones thyroïdiennes; Oiseaux; [SDV.SA]Life Sciences [q-bio]/Agricultural sciences; Manchots; Antarc*; Antarctica; Pygoscelis adeliae
• Online Access: https://tel.archives-ouvertes.fr/tel-01127600; https://tel.archives-ouvertes.fr/tel-01127600/document; https://tel.archives-ouvertes.fr/tel-01127600/file/2013LYO10276.pdf

Cold-exposed young birds maintain their homeothermy by stimulating mitochondrial oxidations in skeletal muscle. Prolonged cold exposure enhances muscle thermogenic capacities through mitochondrial bioenergetics plasticity which control still remains hypothetical. In mammals, fusion proteins (mitofusins (Mfns) and OPA1 (Optic Atrophy 1)) contribute to the permanent and dynamic changes in mitochondrial networks in multiple cell types. The aim of our work was to characterize the expression of avian homologues of mammalian fusion proteins and to study the variations of their expression during the establishment of bioenergetics processes in growing birds, during an acute or a prolonged cold exposure and finally during nutritional or endocrine challenges. Methodologically, an integrative approach has been used from whole animal (indirect calorimetry) to protein (western-blot) or gene (RT-PCR) expression through measurements of the bioenergetics functionality of permeabilized muscle fibers and isolated mitochondria. Two animal models were used, a species naturally adapted to Antarctica harsh conditions, the Adélie penguin (Pygoscelis adeliae), and a laboratory model, the Muscovy duck (Cairina moschata).Our results allowed us to characterize, in birds, the expression of immunoreactive fusion proteins (Mfn2, OPA1) which were homologous to those of mammals. The sequencing of a part of the coding sequence of Mfns genes showed a great similitude between avian and mammalian species. In penguins, the relative abundance of these proteins in muscle mitochondria was modified by growth in the cold and was positively correlated with muscle bioenergetics capacities. In ducks, the respiratory activity and the relative abundance of these proteins were also correlated after a 60h fasting period or,though a lesser extent, after a pharmacological alteration of thyroid status. Our results show, for the first time in birds, the expression of proteins homologous to mammalian fusion proteins. The association between the changes in ...