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The uncoupling protein thermogenin during acclimation: indications for pretranslational control
A Jacobsson1, M Mühleisen, B Cannon
1Wenner-Gren Institute, Arrhenius Laboratories F3, Stockholm University, Sweden.
The American Journal of Physiology
|October 1, 1994
Summary
Cold exposure increases brown fat thermogenin (uncoupling protein) and mRNA levels. While glycerol-phosphate dehydrogenase mRNA and protein levels correlate, thermogenin shows a time delay, suggesting complex regulation beyond simple mRNA control.
Area of Science:
- Physiology
- Molecular Biology
- Biochemistry
Background:
- Brown adipose tissue (BAT) is crucial for thermogenesis.
- Understanding the regulation of thermogenin (uncoupling protein 1) is key to BAT function.
- Investigating the relationship between mRNA and protein levels provides insights into gene expression control.
Purpose of the Study:
- To analyze the regulation of thermogenin content in brown adipose tissue during cold acclimation.
- To investigate the relationship between thermogenin mRNA and protein levels over time.
- To determine if pretranslational control adequately explains thermogenin regulation.
Main Methods:
- Mice were subjected to cold acclimation (transfer from 28°C to 4°C).
- Levels of thermogenin mRNA and protein were measured.
- Cytosolic glycerol-3-phosphate dehydrogenase served as a comparative control.
- Computer simulations were used to model regulatory mechanisms.
Main Results:
- Cold acclimation increased brown fat protein and RNA content.
- Glycerol-3-phosphate dehydrogenase mRNA and protein levels showed acute correlation, indicating pretranslational control.
- Thermogenin mRNA levels increased rapidly, but thermogenin protein levels showed a significant delay (>3 weeks).
- Computer simulations supported a pretranslational control model for thermogenin with a protein half-life of approximately 5 days.
Conclusions:
- Pretranslational control mechanisms, potentially involving a long protein half-life, can explain thermogenin regulation during cold acclimation.
- The regulation of thermogenin differs from that of glycerol-3-phosphate dehydrogenase.
- This study highlights the complex temporal dynamics in protein regulation within brown adipose tissue.