Postnatal appearance of uncoupling protein and formation of thermogenic mitochondria in hamster brown adipose tissue.
Brown adipose tissue of developing hamster was characterized by western blotting, enzyme activity measurements and immunoelectron microscopy. During the first postnatal week the tissue contained significant amounts of differentiating mitochondria and comparable quantities of active cytochrome oxidase and ATP synthase. The uncoupling protein appeared on the 7/8th day and its specific content increased 80-times between day 8 and day 17. In parallel, the specific content and activity of cytochrome oxidase increased 3-times but ATP synthase decreased 2-times. The total content of uncoupling protein and of cytochrome oxidase in interscapular brown adipose tissue increased 360- and 11-times, respectively. Analysis of isolated mitochondria showed that the observed differences result mainly from changes of the enzymic equipment of the mitochondrial membrane. During the same interval, propylthiouracil-insensitive "type II' thyroxine 5'-deiodinase activity in brown adipose tissue increased 10-times. It was concluded that the thermogenic function of the hamster brown adipose tissue develops after the first postnatal week due to highly differentiated synthesis of mitochondrial proteins leading to replacement of preexisting, uncoupling protein-lacking nonthermogenic mitochondria by thermogenic ones, similarly as shown in brown adipose tissue of the embryonic mouse and rat (Houstĕk, J., et al. (1988) Biochim. Biophys. Acta 935, 19-25).
Houstĕk
J
J
Institute of Physiology, Czechoslovak Academy of Sciences, Prague.
Janíková
D
D
Bednár
J
J
Kopecký
J
J
Sebestián
J
J
Soukup
T
T
D002001:Adipose Tissue, Brown / Q000032:analysis / Q000254:growth & development* / Q000648:ultrastructure; D000818:Animals; D000831:Animals, Newborn; D001835:Body Weight; D002352:Carrier Proteins; D006224:Cricetinae; D003576:Electron Transport Complex IV / Q000032:analysis; D004734:Energy Metabolism; D007150:Immunohistochemistry; D007453:Iodide Peroxidase / Q000032:analysis; D007473:Ion Channels; D008565:Membrane Proteins / Q000032:analysis / Q000502:physiology*; D008647:Mesocricetus; D008854:Microscopy, Electron / Q000379:methods; D008928:Mitochondria / Q000502:physiology* / Q000648:ultrastructure; D024101:Mitochondrial Proteins; D006180:Proton-Translocating ATPases / Q000032:analysis; D014475:Uncoupling Agents / Q000032:analysis*; D000071256:Uncoupling Protein 1
D002352:Carrier Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D014475:Uncoupling Agents; D000071256:Uncoupling Protein 1; D007453:Iodide Peroxidase; D003576:Electron Transport Complex IV; D006180:Proton-Translocating ATPases