The Uncoupling Protein Thermogenin During Acclimation: Indications for Pretranslational Control

Am J Physiol. 1994 Oct;267(4 Pt 2):R999-1007. doi: 10.1152/ajpregu.1994.267.4.R999.

Abstract

To analyze the regulation of the content of the uncoupling protein thermogenin in brown adipose tissue, we have selected a physiological transition phase during which to investigate the relationship between the level of mRNA and the level of the ensuing protein product. Mice preacclimated to 28 degrees C were transferred to 4 degrees C. Cold acclimation led to the expected increases in brown fat total protein and RNA content. Two recruited proteins were analyzed: the cytosolic glycerol-3-phosphate dehydrogenase and the mitochondrial uncoupling protein thermogenin. The activity of the dehydrogenase acutely followed the level of the corresponding mRNA, indicating pretranslational control. However, for thermogenin there was a marked time delay between the establishment of the fully recruited level of thermogenin mRNA (after only approximately 4 h of cold exposure) and that of thermogenin itself (after > 3 wk). By reiterative computer simulation, it was investigated whether a model only involving pretranslational regulation could be invoked for either system. For glycerol-phosphate dehydrogenase, a plausible model could be constructed, provided the protein half-life was shorter than approximately 24 h. Despite the long time delay between full thermogenin mRNA recruitment and full thermogenin protein recruitment, a plausible pretranslational control model could also be constructed, provided that the protein half-life was approximately 5 days. This computed value was in good agreement with the half-life obtained from independent thermogenin half-life studies. It is implied that pretranslational control may suffice to explain the regulation of thermogenin content in brown adipose tissue during a warm-to-cold transition period.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acclimatization*
  • Adipose Tissue, Brown / metabolism*
  • Animals
  • Carrier Proteins / biosynthesis*
  • Cold Temperature
  • DNA Probes
  • Enzyme-Linked Immunosorbent Assay
  • Gene Expression*
  • Glycerolphosphate Dehydrogenase / metabolism
  • Ion Channels
  • Male
  • Membrane Proteins / biosynthesis*
  • Mice
  • Mice, Inbred Strains
  • Mitochondrial Proteins
  • RNA, Messenger / analysis
  • RNA, Messenger / biosynthesis*
  • Transcription, Genetic
  • Uncoupling Agents
  • Uncoupling Protein 1

Substances

  • Carrier Proteins
  • DNA Probes
  • Ion Channels
  • Membrane Proteins
  • Mitochondrial Proteins
  • RNA, Messenger
  • Uncoupling Agents
  • Uncoupling Protein 1
  • Glycerolphosphate Dehydrogenase