Characterization of bovine pyruvate carboxylase promoter 1 responsiveness to serum from control and feed-restricted cows

Pyruvate carboxylase (PC; EC 6.4.1.1) is critical in gluconeogenesis from lactate and maintenance of tricarboxylic acid cycle intermediates. Whereas increases in PC mRNA have been observed during feed restriction, the mechanism of regulation is unknown; however, coinciding increases in circulating N...

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Bibliographic Details
Published in:Journal of animal science 2011-06, Vol.89 (6), p.1763-1768
Main Authors: White, H.M, Koser, S.L, Donkin, S.S
Format: Article
Language:English
Subjects:
Animal productions
Animals
Biological and medical sciences
Cattle
Cell Line, Tumor
cows
fatty acid composition
fatty acids
Fatty Acids - blood
Feed and pet food industries
Food Deprivation
Food industries
free fatty acids
Fundamental and applied biological sciences. Psychology
gene expression regulation
Gene Expression Regulation, Enzymologic - physiology
hepatoma
messenger RNA
Promoter Regions, Genetic
pyruvate carboxylase
Pyruvate Carboxylase - genetics
Pyruvate Carboxylase - metabolism
Rats
restricted feeding
Serum
Terrestrial animal productions
tricarboxylic acid cycle
Vertebrates
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Summary:Pyruvate carboxylase (PC; EC 6.4.1.1) is critical in gluconeogenesis from lactate and maintenance of tricarboxylic acid cycle intermediates. Whereas increases in PC mRNA have been observed during feed restriction, the mechanism of regulation is unknown; however, coinciding increases in circulating NEFA concentrations suggests that fatty acids may contribute to regulation of gene expression during feed restriction. The objective of this study was to examine the direct effect of exposure to serum from full-fed control cows with serum from cows that were restricted to 50% of ad libitum intake for 5 d on PC expression in vitro. Rat hepatoma (H4IIE) cells were transiently transfected with bovine promoter-luciferase constructs containing bovine PC promoter 1 and treated with serum from control cows, serum from feed-restricted cows, or modified serum. Modified serum pools were generated by supplemented serum from control cows with C14:0, C16:0, C18:0, C18:1n-9 cis, C18:2n-6 cis, and C18:3n-3 cis to match the total NEFA in serum from feed-restricted cows (1.3 mM) in the relative proportion found in serum from control or feed-restricted cows. Exposure of cells to serum from feed-restricted cows increased (P < 0.05) PC promoter 1 activity 2.2-fold compared with cells exposed to control cow serum. Exposure to serum from control cows with fatty acids added to a NEFA concentration of 1.3 mM to reflect the fatty acid profile of control and feed-restricted cows increased (P < 0.05) promoter 1 activity 2.1- and 2.5-fold, respectively, compared with cells incubated with control cow serum. There was no difference (P ≥ 0.05) in promoter 1 activity in cells treated with modified serum compared with serum from feed-restricted cows. These data indicate that promoter 1 is activated by fatty acids found in serum of feed-restricted cows. These data suggest a role of NEFA to regulate expression of bovine PC mRNA through specific activation of PC promoter 1.
ISSN:0021-8812
1525-3163
DOI:10.2527/jas.2010-3407