GSE183063
Assaying peroxisome proliferator-activated receptor activation in the peripartum using precision-cut bovine liver slices reveals novel putative PPAR targets in dairy cows.
Metabolic challenges experienced by dairy cows during the transition between pregnancy and lactation (also known as peripartum), are of considerable interest from a nutrigenomic perspective. The mobilization of large amounts of non-esterified fatty acids (NEFA) leads to an increase in NEFA uptake in the liver, the excess of which can cause hepatic accumulation of lipids and ultimately fatty liver. Interestingly, peripartum NEFA activate the peroxisome proliferator-activated receptor (PPAR), a transcriptional regulator with known nutrigenomic properties. The study of PPAR activation in the liver of periparturient dairy cows is thus crucial; however, current in vitro models of the bovine liver are inadequate, and the isolation of primary hepatocytes is prohibitive and error-prone. The objective of the current study was to evaluate the use of precision-cut liver slices (PCLS) from liver biopsies as a model for PPAR activation in periparturient dairy cows. Four cows were enrolled in the experiment, and PCLS from each were prepared prepartum (-10 DIM) and postpartum (+10 DIM) and treated with a variety of PPAR agonists and antagonist. Gene expression was assayed through RT-qPCR and RNAseq, and intracellular triglyceride concentration was measured. PCLS treated with PPAR? agonist rosiglitazone displayed upregulation of canonical PPAR targets ACADVL and LIPC in the postpartum, while a PPARd agonists increased expression of PPAR target PDK4; no gene expression changes were detected in the prepartum, and triglyceride concentrations were unchanged between treatments. Transcriptome sequencing revealed considerable differences in response to PPAR agonist, mainly related to pathways involved with lipid metabolism and the immune response. Among differentially expressed genes, a subset of 91 genes were identified as novel putative PPAR targets in the bovine liver, by cross-referencing our results with a publicly-available dataset of predicted PPAR target genes, and supplementing our finding with prior literature. Our results provide important insights on the use of PCLS as a model for assaying PPAR activation in the peripartum. Overall design: Gene expression profiling on precision-cut liver slices from 4 early postpartum cows treated with PPAR agonists. Precision-cut liver slices (PCLS) from each animal were treated with 100 µM of the PPARa agonist WY-14643, or 50 µM of the PPARd agonist GW-501516, or 100 µM of the PPAR? agonist rosiglitazone, or were left untreated. RNA was isolated and sequenced after 18 hours of incubation