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Journal of Lipid Research, Vol. 49, 332-339, February 2008
Copyright © 2008 by American Society for Biochemistry and Molecular Biology

* University of Pecs, Medical Faculty, Department of Biochemistry and Medical Chemistry, H-7624 Pecs, Hungary
University of Szeged, Department of Medical Chemistry, H-6720 Szeged, Hungary
Published, JLR Papers in Press, November 5, 2007.
1 To whom correspondence should be addressed. e-mail: atila.sandor{at}aok.pte.hu
Rats were exposed to cold and then reacclimated at neutral temperature. Changes related to fatty acid and glucose metabolism in brown and white adipose tissues (BAT and WAT) and in muscle were then examined. Of the many proteins involved in the metabolic response, two lipogenic enzymes, acetyl-coenzyme A carboxylase (ACC) and ATP-citrate lyase, were found to play a pervasive role and studied in detail. Expression of the total and phosphorylated forms of both lipogenic enzymes in response to cold increased in BAT but decreased in WAT. Importantly, in BAT, only the phosphorylation of the ACC1 isoenzyme was enhanced, whereas that of ACC2 remained unchanged. The activities of these enzymes and the in vivo rate of FFA synthesis together suggested that WAT supplies BAT with FFA and glucose by decreasing its own synthetic activity. Furthermore, cold increased the glucose uptake of BAT by stimulating the expression of components of the insulin signaling cascade, as observed by the enhanced expression and phosphorylation of Akt and GSK-3. In muscle, these changes were observed only during reacclimation, when serum insulin also increased. Such changes may be responsible for the extreme glycogen accumulation in the BAT of rats reacclimated from cold.
Supplementary key words brown adipose tissue white adipose tissue lipogenic enzymes insulin signaling phosphorylation
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