Submitted to: International Symposium on Avian Endocrinology Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/11/2008
Publication Date: 7/11/2008
Citation: Proszkowiec-Weglarz, M.,Richards, M.P., Humphrey, B.D. 2008. Role of AMP-activated protein kinase and carbohydrate response element binding protein in the regulation of energy balance in chickens [abstract]. In: Proceedings of the Ninth International Symposium on Avian Endocrinology. Abstract Number 215.
Technical Abstract: AMP-activated protein kinase (AMPK) is a heterotrimeric enzyme complex playing a key role in maintaining intracellular energy balance and, on the whole animal level, regulating energy expenditure and food intake. Once activated by phosphorylation, AMPK phosphorylates a variety of protein targets that influence carbohydrate, protein and lipid metabolism. Carbohydrate response element binding protein (ChREBP) is a glucose-responsive transcription factor involved in the regulation of glucose metabolism and lipid synthesis. When activated by dephosphorylation, ChREBP increases the transcription of glycolytic and lipogenic enzyme genes in liver. The aim of this study was to characterize AMPK and ChREBP activity, mRNA and protein expression, and the expression of their target genes involved in lipid metabolism during fasting and refeeding in broiler chicken liver. In response to changes in energy state (2-48h fasting followed by 2-24h refeeding), no changes in expression of the AMPK alpha subunit were observed, while ChREBP mRNA levels decreased during fasting. AMPK activity and the phosphorylation level of acetyl-CoA carboxylase (ACC) increased, whereas ChREBP activity decreased in liver during fasting. The mRNA levels of sterol regulatory binding protein-1, ACC, ATP-cytrate lyase, fatty acid synthase, Spot14, malic enzyme and stearoyl-CoA desaturase-1 decreased during negative energy balance in chicken liver. Plasma glucose and insulin decreased, whereas glucagon increased in response to fasting. These results suggest that, as in mammals, AMPK and ChREBP play important roles in the regulation of lipid metabolism in chicken liver and that they are key molecular components of a mechanism working to maintain energy balance.