Submitted to: Poultry Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/12/2007
Publication Date: 7/1/2007
Citation: Proszkowiec-Weglarz, M., Humphrey, B., Richards, M.P., Rosebrough, R.W., McMurtry, J.P., Angel, R. 2007. Expression of the carbohydrate response element binding protein gene and related genes involved in hepatic lipogenesis during post-hatch development of broiler chickens [abstract]. Poultry Science. 86(Supplement 1):paper number 462.
Technical Abstract: Carbohydrate response element binding protein (ChREBP) and sterol regulatory element binding protein-1c (SREBP-1c) are important regulators of glucose metabolism and lipid synthesis in mammals. In response to glucose (ChREBP) and insulin (SREBP-1c), these two transcription factors regulate the expression of lipogenic enzyme genes such as acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), stearoyl-CoA desaturase 1 (SCD1), ATP citrate lyase (ACL), and malic enzyme (ME). ChREBP dimerizes with Max-like protein X (Mlx) and binds to carbohydrate response element sites in target gene promoter regions. Expression of ChREBP and SREBP-1c is regulated, in part, by the nuclear liver X receptor (LXR). Since the ChREBP gene has not been identified in birds, the aim of this work was to characterize it and to determine its expression and the expression of related genes in broilers during post-hatch (PH) development. To identify gene transcripts and determine their expression by RT-PCR, total RNA was isolated from 10 different tissues from 3-wk-old birds and from the livers of birds at 0, 1, 2, 3, 4, 6, and 8 d PH that were fed or fasted for 48 h PH. ChREBP, SREBP-1c, Mlx, and LXR gene homologues were expressed in all tissues examined at 3 wk. ChREBP demonstrated significant tissue-specific expression with high mRNA levels found in liver and duodenum. Fasting for 48h PH did not change Mlx or ChREBP expression, whereas SREBP-1c expression was lower at 2 d in fasted compared to fed chicks. Increases in ACC, FAS, SCD1, and ME gene expression were observed in response to feeding. Fasting for 48 h PH delayed the rise in lipogenic enzyme gene expression but had no effect on plasma insulin or glucagon. We suggest that ChREBP functions in the glucose-dependent regulation of lipid synthesis in chickens as it does in mammals.