EXPRESSION OF SELECTED LIPOGENIC GENES AND FATTY ACID TRANSPORTERS CHANGES ACROSS STAGES OF LACTATION IN DAIRY EWES

Abstract

Background. During lactation the mammary fat synthesis is increased compared to adipose tissue. Objective. This study evaluated the promoter specific gene expression of acetyl-CoA carboxylase alpha (ACACA) transcripts from promoters II and III, fatty acid synthase (FASN), sterol regulatory element binding transcription factor 1 (SREBF1) in mammary gland and adipose tissue and, peroxisome proliferator-activated receptor gamma (PPARG), fatty acid transporters acyl-CoA synthetase long chain family member 1 (ACSL1), solute carrier family 27 member 6 (SLC27A6), fatty acid binding proteins 3 and 4 (FABP3 and FABP4), CD36 molecule (CD36) and lipoprotein lipase (LPL) in the mammary gland. Methodology. Eight Lacaune lactating ewes at 15, 70, and 120 days in milk (DIM) were used. Results. There was no effect of tissue, lactation stage, or tissue by lactation stage interaction for PIII ACACA transcripts. Mammary PII transcripts changed according to stage of lactation with higher expression at 15 than 120 DIM. In adipose tissue at 120 DIM, expression of PII ACACA transcripts were higher than 15 and 70 DIM. Expression of FASN in adipose tissue was higher at 70 and 120 DIM when compared to mammary tissue at 120 DIM. The SREBF1 expression at 70 was higher than 15 DIM in mammary tissue and higher than 70 DIM in adipose tissue. In the mammary gland, the gene expression of LPL, CD36 and FABP3 was decreased from 15 to 120 DIM. Implications. Collectively, our results highlight the fact that in early lactation (15 to 70 DIM) milk fat synthesis is prioritized over adipose tissue in dairy sheep. Conclusion. This prioritization is managed through an orchestrated increase in mammary gene expression of ACACA transcripts, FASN, SREBF1, LPL, CD36, and FABP3.