title: Epigenetic regulation of pyruvate carboxylase gene expression in the postpartum liver.
abstract: Hepatic gluconeogenesis is essential for maintenance of whole body glucose homeostasis and glucose supply for mammary lactose synthesis in the dairy cow. Upregulation of the gluconeogenic enzyme pyruvate carboxylase (PC) during the transition period is vital in the adaptation to the greater glucose demands associated with peripartum lactogenesis. The objective of this study was to determine if PC transcription in hepatocytes is regulated by DNA methylation and if treatment with a nonsteroidal anti-inflammatory drug (NSAID) alters methylation of an upstream DNA sequence defined as promoter 1. Dairy cows were left untreated (n=20), or treated with a NSAID during the first 5 d postcalving (n=20). Liver was biopsied at d 7 precalving and d 7, 14, and 28 postcalving. Total PC and transcript specific gene expression was quantified using quantitative PCR and DNA methylation of promoter 1 was quantified using bisulfite Sanger sequencing. Expression of PC changed over the transition period, with increased expression postcalving occurring concurrently with increased circulating concentration of nonesterified fatty acids. The DNA methylation percentage was variable at all sites quantified and ranged from 21 to 54% across the 15 CpG dinucleotides within promoter 1. The DNA methylation at wk 1 postcalving, however, was not correlated with gene expression of promoter 1-regulated transcripts and we did not detect an effect of NSAID treatment on DNA methylation or PC gene expression. Our results do not support a role for DNA methylation in regulating promoter 1-driven gene expression of PC at wk 1 postcalving. Further research is required to determine the mechanisms regulating increased PC expression over the transition period.
authors.affiliation: DairyNZ Limited, School of Biological Sciences, University of Auckland, Auckland, New Zealand 1010. Electronic address: Caroline.walker@dairynz.co.nz.
authors.forename: C G
authors.initials: CG
authors.lastname: Walker
authors.affiliation: DairyNZ Limited, School of Biological Sciences, University of Auckland, Auckland, New Zealand 1010.
authors.forename: M A
authors.initials: MA
authors.lastname: Crookenden
authors.affiliation: School of Biological Sciences, University of Auckland, Auckland, New Zealand 1010.
authors.forename: K M
authors.initials: KM
authors.lastname: Henty
authors.affiliation: DairyNZ Limited, School of Biological Sciences, University of Auckland, Auckland, New Zealand 1010; School of Biological Sciences, University of Auckland, Auckland, New Zealand 1010.
authors.forename: R R
authors.initials: RR
authors.lastname: Handley
authors.affiliation: DairyNZ Limited, Private bag 3221, Hamilton, New Zealand 3240.
authors.forename: B
authors.initials: B
authors.lastname: Kuhn-Sherlock
authors.affiliation: Department of Dairy Science, College of Agricultural and Life Sciences, University of Wisconsin, Madison 53706.
authors.forename: H M
authors.initials: HM
authors.lastname: White
authors.affiliation: Department of Animal Science, Purdue University, West Lafayette, IN 47907.
authors.forename: S S
authors.initials: SS
authors.lastname: Donkin
authors.affiliation: DairyNZ Limited, Private bag 3221, Hamilton, New Zealand 3240.
authors.forename: R G
authors.initials: RG
authors.lastname: Snell
authors.affiliation: DairyNZ Limited, Private bag 3221, Hamilton, New Zealand 3240.
authors.forename: S
authors.initials: S
authors.lastname: Meier
authors.affiliation: AgResearch, Hopkirk Research Institute, Grasslands Research Centre, Palmerston North, New Zealand 4442.
authors.forename: A
authors.initials: A
authors.lastname: Heiser
authors.affiliation: Department of Animal Sciences, University of Illinois, Urbana 61801.
authors.forename: J J
authors.initials: JJ
authors.lastname: Loor
authors.affiliation: University of Queensland, Centre for Clinical Research, Royal Brisbane & Women's Hospital Campus, Herston, Queensland 4029, Australia.
authors.forename: M D
authors.initials: MD
authors.lastname: Mitchell
authors.affiliation: DairyNZ Limited, Private bag 3221, Hamilton, New Zealand 3240.
authors.forename: J R
authors.initials: JR
authors.lastname: Roche
mesh_terms: D000818:Animals; D002417:Cattle; D044127:Epigenesis, Genetic; D005260:Female; D015870:Gene Expression; D005786:Gene Expression Regulation; D007774:Lactation; D008099:Liver / Q000378:metabolism; D008892:Milk / Q000378:metabolism; D049590:Postpartum Period / Q000378:metabolism; D011766:Pyruvate Carboxylase / Q000378:metabolism*
chemical_list: D011766:Pyruvate Carboxylase
keywords: epigenetic; gluconeogenesis; transcription