Negative energy balance and hepatic gene expression patterns in high-yielding dairy cows during the early postpartum period: a global approach

Abstract

In high-yielding dairy cows the liver undergoes extensive physiological and biochemical changes during the early postpartum period in an effort to re-establish metabolic homeostasis and to counteract the adverse effects of negative energy balance (NEB). These adaptations are likely to be mediated by significant alterations in hepatic gene expression. To gain new insights into these events an energy balance model was created using differential feeding and milking regimes to produce two groups of cows with either a mild (MNEB) or severe NEB (SNEB) status. Cows were slaughtered and liver tissues collected on days 6-7 of the first follicular wave postpartum. Using an Affymetrix 23k oligonucleotide bovine array to determine global gene expression in hepatic tissue of these cows, we found a total of 416 genes (189 up- and 227 downregulated) to be altered by SNEB. Network analysis using Ingenuity Pathway Analysis revealed that SNEB was associated with widespread changes in gene expression classified into 36 gene networks including those associated with lipid metabolism, connective tissue development and function, cell signaling, cell cycle, and metabolic diseases, the three most significant of which are discussed in detail. SNEB cows displayed reduced expression of transcription activators and signal transducers that regulate the expression of genes and gene networks associated with cell signaling and tissue repair. These alterations are linked with increased expression of abnormal cell cycle and cellular proliferation associated pathways. This study provides new information and insights on the effect of SNEB on gene expression in high-yielding Holstein Friesian dairy cows in the early postpartum period.

Fig. 1.

Classification of differentially expressed genes (DEG) according to top 20 molecular and cellular functions, most significantly affected by energy balance (EB) using Ingenuity Pathways Analysis. The blue bars indicate the likelihood [−log (P-value)] that the specific molecular and cellular function category was affected by negative energy balance compared with others represented in the list of DEG. The number of up- and downregulated genes in each group is represented on the righthand side by red and green numbers, respectively. The cut-off (yellow line) is shown at P < 0.05 (1.301 log scale).

Fig. 2.

Network #1: lipid metabolism, molecular transport, small molecule biochemistry. The network is displayed graphically as nodes (genes). The node color intensity indicates the expression of genes, with red representing upregulation and green downregulation in severe negative energy balance (SNEB) versus mild negative energy balance (MNEB) liver. The fold value is indicated under each node. The shapes of nodes indicate the functional class of the gene product, and the lines indicate the type of interaction (Supplementary Fig. S1).

Fig. 3.

Network #2: lipid metabolism, small molecule biochemistry, cell cycle. The network is displayed graphically as nodes (genes). The node color intensity indicates the expression of genes, with red representing upregulation and green downregulation in SNEB versus MNEB liver. The fold value is indicated under each node. The shapes of nodes indicate the functional class of the gene product and the lines indicate the type of interaction (Supplementary Fig. S1).

Fig. 4.

Network #3: gene expression, cellular compromise, DNA replication, recombination, and repair. The network is displayed graphically as nodes (genes). The node color intensity indicates the expression of genes, with red representing upregulation and green downregulation in SNEB versus MNEB liver. The fold value is indicated under each node. The shapes of nodes indicate the functional class of the gene product and the lines indicate the type of interaction (Supplementary Fig. S1).