Variants in the 3'UTR of the ovine Acetyl-Coenzyme A Acyltransferase 2 gene are associated with dairy traits and exhibit differential allelic expression

D Miltiadou, A. L. Hager-Theodorides, S Symeou, C. Constantinou, Androniki Psifidi, Georgios Banos, O. Tzamaloukas

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The Acetyl-CoA acyltransferase 2 (ACAA2) gene encodes an enzyme of the thiolase family that is involved in mitochondrial fatty acid elongation and degradation by catalyzing the last step of the respective β-oxidation pathway. The increased energy needs for gluconeogenesis and triglyceride synthesis during lactation are met primarily by increased fatty acid oxidation. Therefore, the ACAA2 enzyme plays an important role in the supply of energy and carbon substrates for lactation and may thus affect milk production traits. This study investigates the association of the ACAA2 gene with important sheep traits and the putative functional involvement of this gene in dairy traits. A single nucleotide substitution (SNP), a T to C transition located in the 3' untranslated region (UTR) of the ACAA2 gene, was used in mixed model association analysis with milk yield, milk protein yield and percentage, milk fat yield and percentage, and litter size at birth. The SNP was significantly associated with total lactation production and milk protein percentage, with respective additive effects of 6.81 ± 2.95 kg and -0.05 ± 0.02 %. Additionally, a significant dominance effect of 0.46 ± 0.21 was detected for milk fat yield. Homozygous TT and heterozygous CT animals exhibited higher milk yield compared to homozygous CC animals, while the latter exhibited increased milk protein percentage. Expression analysis from age, lactation and parity matched female sheep showed that mRNA expression of the ACAA2 gene from TT animals was 2.8 and 11.8 fold higher in liver and mammary gland, respectively. In addition, by developing an allelic expression imbalance (AEI) assay, it was estimated that the T allele was expressed at an average of 18% more compared to the C allele in the udder of randomly selected ewes. We demonstrated for the first time that the variants in the 3'UTR of the ovine ACAA2 gene are differentially expressed in homozygous ewes of each allele and exhibit AEI within heterozygotes in a tissue specific manner, supporting the existence of cis-regulatory DNA variation in the ovine ACAA2 gene. This is the first study reporting differential allelic imbalance expression of a candidate gene associated with milk production traits in dairy sheep.
Original languageEnglish
Pages (from-to)6285-6297
JournalJournal of Dairy Science
Issue number8
Early online date16 Jun 2017
Publication statusPublished - Aug 2017

Keywords / Materials (for Non-textual outputs)

  • ACAA2 association
  • 3' UTR Cis-acting SNP
  • gene expression
  • dairy sheep


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