title: Expression of the uncoupling protein 1 from the aP2 gene promoter stimulates mitochondrial biogenesis in unilocular adipocytes in vivo.
abstract: Mitochondrial uncoupling protein 1 (UCP1) is a specific marker of multilocular brown adipocytes. Ectopic UCP1 in white fat of aP2-Ucp1 mice mitigates development of obesity by both, increasing energy expenditure and decreasing in situ lipogenesis. In order to further analyse consequences of respiratory uncoupling in white fat, the effects of the ectopic UCP1 on the morphology of adipocytes and biogenesis of mitochondria in these cells were studied. In subcutaneous white fat of both aP2-Ucp1 and young control (5-week-old) mice, numerous multilocular adipocytes were found, while they were absent in adult (7- to 9-month-old) animals. Only unilocular cells were present in epididymal fat of both genotypes. In both fat depots of aP2-Ucp1 mice, the levels of the UCP1 transcript and UCP1 antigen declined during ageing, and they were higher in subcutaneous than in epididymal fat. Under no circumstances could ectopic UCP1 induce the conversion of unilocular into multilocular adipocytes. Presence of ectopic UCP1 in unilocular adipocytes was associated with the elevation of the transcripts for UCP2 and for subunit IV of mitochondrial cytochrome oxidase (COX IV), and increased content of mitochondrial cytochromes. Electron microscopy indicated changes of mitochondrial morphology and increased mitochondrial content due to ectopic UCP1 in unilocular adipocytes. In 3T3-L1 adipocytes, 2,4-dinitrophenol increased the levels of the transcripts for both COX IV and for nuclear respiratory factor-1. Our results indicate that respiratory uncoupling in unilocular adipocytes of white fat is capable of both inducing mitochondrial biogenesis and reducing development of obesity.
authors.affiliation: Department of Adipose Tissue Biology and Center for Integrated Genomics, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Rossmeisl
authors.forename: Giorgio
authors.initials: G
authors.lastname: Barbatelli
authors.forename: Pavel
authors.initials: P
authors.lastname: Flachs
authors.forename: Petr
authors.initials: P
authors.lastname: Brauner
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Zingaretti
authors.forename: Mariella
authors.initials: M
authors.lastname: Marelli
authors.forename: Petra
authors.initials: P
authors.lastname: Janovská
authors.forename: Milada
authors.initials: M
authors.lastname: Horáková
authors.forename: Ivo
authors.initials: I
authors.lastname: Syrový
authors.forename: Saverio
authors.initials: S
authors.lastname: Cinti
authors.forename: Jan
authors.initials: J
authors.lastname: Kopecký
mesh_terms: D017667:Adipocytes / Q000378:metabolism* / Q000648:ultrastructure; D000375:Aging / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D007473:Ion Channels; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000502:physiology* / Q000648:ultrastructure; D024101:Mitochondrial Proteins; D009765:Obesity / Q000517:prevention & control; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis; D000071256:Uncoupling Protein 1
chemical_list: D002352:Carrier Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; C000604372:Ucp1 protein, mouse; D000071256:Uncoupling Protein 1