Low content of mitochondrial ATPase in brown adipose tissue is the result of post-transcriptional regulation.

The mRNA levels of ATPase beta, ATPase 6, cytochrome oxidase (COX) VIb and COX I subunits were found to be 2.4-13.8-fold higher in brown adipose tissue (BAT) than in heart, skeletal muscle, brain and liver of mice. The comparison with tissue contents of ATPase and COX revealed that the selective, 5-11-fold reduction of ATPase in BAT is not caused by decreased transcription of ATPase genes. Likewise, the ATPase beta and COX VIb mRNA levels in cultured brown adipocytes were also not influenced by norepinephrine, which activated the expression of the UCP gene by two orders of magnitude. The results indicate that the biosynthesis of mitochondrial ATPase in BAT is post-transcriptionally regulated.