title: The brown and brite adipocyte marker Cox7a1 is not required for non-shivering thermogenesis in mice.
abstract: The cytochrome c oxidase subunit isoform Cox7a1 is highly abundant in skeletal muscle and heart and influences enzyme activity in these tissues characterised by high oxidative capacity. We identified Cox7a1, well-known as brown adipocyte marker gene, as a cold-responsive protein of brown adipose tissue. We hypothesised a mechanistic relationship between cytochrome c oxidase activity and Cox7a1 protein levels affecting the oxidative capacity of brown adipose tissue and thus non-shivering thermogenesis. We subjected wildtype and Cox7a1 knockout mice to different temperature regimens and tested characteristics of brown adipose tissue activation. Cytochrome c oxidase activity, uncoupling protein 1 expression and maximal norepinephrine-induced heat production were gradually increased during cold-acclimation, but unaffected by Cox7a1 knockout. Moreover, the abundance of uncoupling protein 1 competent brite cells in white adipose tissue was not influenced by presence or absence of Cox7a1. Skin temperature in the interscapular region of neonates was lower in uncoupling protein 1 knockout pups employed as a positive control, but not in Cox7a1 knockout pups. Body mass gain and glucose tolerance did not differ between wildtype and Cox7a1 knockout mice fed with high fat or control diet. We conclude that brown adipose tissue function in mice does not require the presence of Cox7a1.
authors.affiliation: Chair of Molecular Nutritional Medicine, Technische Universität München, Else Kröner-Fresenius Center for Nutritional Medicine &ZIEL-Institute for Food and Health, 85350 Freising-Weihenstephan, Germany.
authors.forename: Stefanie F
authors.initials: SF
authors.lastname: Maurer
authors.affiliation: Chair of Molecular Nutritional Medicine, Technische Universität München, Else Kröner-Fresenius Center for Nutritional Medicine &ZIEL-Institute for Food and Health, 85350 Freising-Weihenstephan, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Fromme
authors.affiliation: Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors.forename: Lawrence I
authors.initials: LI
authors.lastname: Grossman
authors.affiliation: Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors.forename: Maik
authors.initials: M
authors.lastname: Hüttemann
authors.affiliation: Chair of Molecular Nutritional Medicine, Technische Universität München, Else Kröner-Fresenius Center for Nutritional Medicine &ZIEL-Institute for Food and Health, 85350 Freising-Weihenstephan, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Klingenspor
mesh_terms: D000064:Acclimatization / Q000235:genetics*; D017667:Adipocytes / Q000378:metabolism* / Q000502:physiology; D002001:Adipose Tissue, Brown / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D003080:Cold Temperature; D059305:Diet, High-Fat; D003576:Electron Transport Complex IV / Q000096:biosynthesis* / Q000235:genetics; D005947:Glucose / Q000378:metabolism; D007473:Ion Channels / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D012768:Shivering / Q000502:physiology; D013312:Stress, Physiological / Q000235:genetics; D022722:Thermogenesis / Q000235:genetics*; D000071256:Uncoupling Protein 1
chemical_list: D007473:Ion Channels; D024101:Mitochondrial Proteins; C000604372:Ucp1 protein, mouse; D000071256:Uncoupling Protein 1; D003576:Electron Transport Complex IV; C573492:cytochrome c oxidase subunit 7a1, mouse; D005947:Glucose; D009638:Norepinephrine