Comparative transcriptome analysis of goat (Capra hircus) adipose tissue reveals physiological regulation of body reserve recovery after the peak of lactation.

Adipose tissue is the energy storage organ providing energy to other tissues, including mammary gland, that supports the achievement of successive lactation cycles. Our objective was to investigate the ability of goats to restore body fat reserves by comparing lipogenic enzyme activities and by transcriptomic RNA-Seq data at two different physiological stages, mid- and post-lactation. Key lipogenic enzyme activities were higher in goat omental adipose tissue during mid-lactation (74 days in milk) than during the post-lactation period (300 days postpartum). RNA-Sequencing analysis revealed 19,271 expressed genes in the omental adipose tissue. The comparison between adipose transcriptome analysis from mid- and post-lactation goats highlighted 252 differentially expressed genes (p < 0.05) between these two physiological stages. The differential expression of 11 genes was confirmed by RT-qPCR. Functional genomic analysis revealed that 31% were involved in metabolic processes among which 38% in lipid metabolism. Most of the genes involved in lipid synthesis and those in lipid transport and storage were upregulated in adipose tissue of mid- compared to post-lactation goats. In addition, adipose tissue plasticity was emphasized by genes involved in cellular signaling and tissue integrity. Network analyses also highlighted three key regulators of lipid metabolism (LEP, APOE and HNF4A) and a key target gene (VCAM1). The greatest lipogenic enzyme activities with the upregulation of genes involved in lipid metabolism highlighted a higher recovery of lipid reserves after the lactation peak than 4 months post-lactation. This study contributes to a better understanding of the molecular mechanisms controlling the body lipid reserves management during the successive lactations.