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.
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.
Martin
I
I
Department de Bioquímica i Fisiologia, Universitat de Barcelona, Spain.
Giralt
M
M
Viñas
O
O
Iglesias
R
R
Mampel
T
T
Villarroya
F
F
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
D004272:DNA, Mitochondrial; D012333:RNA, Messenger; D000077278:RNA, Mitochondrial; D012313:RNA; D000226:Mitochondrial ADP, ATP Translocases; D003576:Electron Transport Complex IV