title: Co-ordinate decrease in the expression of the mitochondrial genome and nuclear genes for mitochondrial proteins in the lactation-induced mitochondrial hypotrophy of rat brown fat.
abstract: The relative abundance of the mitochondrial-encoded mRNAs for cytochrome c oxidase subunit II and NADH dehydrogenase subunit I was lower in brown adipose tissue (BAT) from lactating rats than in virgin controls. This decrease was in parallel with a significant decrease in mitochondrial 16 S rRNA levels and in the relative content of mitochondrial DNA in the tissue. BAT from lactating rats showed lowered mRNA expression of the nuclear-encoded genes for the mitochondrial uncoupling protein, subunit IV of cytochrome c oxidase and the adenine nucleotide translocase isoforms ANT1 and ANT2, whereas mRNA levels for the ATP synthase beta-subunit were unchanged. However, the relative content of this last protein was lower in BAT mitochondria from lactating rats than in virgin controls. It is concluded that lactation-induced mitochondrial hypotrophy in BAT is associated with a co-ordinate decrease in the expression of the mitochondrial genome and nuclear genes for mitochondrial proteins. This decrease is caused by regulatory events acting at different levels, including pre- and post-transcriptional regulation. BAT appears to be a useful model with which to investigate the molecular mechanisms involved in the co-ordination of the expression of the mitochondrial and nuclear genomes during mitochondrial biogenesis.
authors.affiliation: Department de Bioquímica i Fisiologia, Universitat de Barcelona, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Martin
authors.forename: M
authors.initials: M
authors.lastname: Giralt
authors.forename: O
authors.initials: O
authors.lastname: Viñas
authors.forename: R
authors.initials: R
authors.lastname: Iglesias
authors.forename: T
authors.initials: T
authors.lastname: Mampel
authors.forename: F
authors.initials: F
authors.lastname: Villarroya
mesh_terms: D002001:Adipose Tissue, Brown / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D015152:Blotting, Northern; D015139:Blotting, Southern; D015153:Blotting, Western; D002467:Cell Nucleus / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics; D006801:Humans; D007774:Lactation / Q000502:physiology*; D008928:Mitochondria / Q000737:chemistry / Q000235:genetics*; D000226:Mitochondrial ADP, ATP Translocases / Q000235:genetics / Q000378:metabolism; D012313:RNA; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D000077278:RNA, Mitochondrial; D051381:Rats; D017208:Rats, Wistar
chemical_list: D004272:DNA, Mitochondrial; D012333:RNA, Messenger; D000077278:RNA, Mitochondrial; D012313:RNA; D000226:Mitochondrial ADP, ATP Translocases; D003576:Electron Transport Complex IV