Use of a short-term nutritional supplementation for transcriptional profiling of liver tissues in sheep

Abstract

This study aimed to evaluate if a short-term nutritional supplementation has any stimulatory effects on liver function and metabolic status in sheep. The experiment was carried out using 30 Dorset×Han crossbred ewes (age, 9 ± 0.6 months; weight, 36.58 ± 2.56 kg) allocated into two treatments, the control group (AD group: DE 11.72 MJ/d; DP 79.71 g/d) and the nutritional supplementation group (HE group: DE18.75 MJ/d; DP 108.44 g/d), respectively. Experiment lasted 20 days, including 10 d for adaption. Blood samples of these ewes were collected to detect the concentrations of glucose, insulin, leptin, and cholesterol. Then, liver samples of these animals were collected to explore the genome-wide transcriptome analysis. Results showed that the weight gain was significantly increased in the nutritional supplementation group, compared with those in the control group (p = 1.27e-03). The concentrations of glucose, insulin, leptin, and cholesterol were also influenced, compared with the AD groups, higher glucose concentrations ranging from 0.10 to 1.11 mmol/L were observed in the HE groups. The concentrations of insulin and leptin varied over time and they were higher in HE groups. The cholesterol concentration was lower in the HE groups. Furthermore, 622 differentially expressed genes (DEGs) were identified between different treatments. Of these, 271 genes were down regulated while 351 genes were up regulated. qRT-PCR analysis of 10 randomly selected genes were consistent with the sequencing results. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways revealed these DEGs in HE group were significantly enriched in energy and lipid metabolism, such as cellular carbohydrate catabolic and metabolic process (DGKI, SOCS2, GHR, GHRHR, CSKMT), lipid metabolic and transport process (ALDH6A1, ABCA9, G0S2, PPARGC1) and monosaccharide metabolic process (PDK4, LPIN1, ABCA9, SLC45A3), etc. Additionally, we concluded an interaction network related to energy metabolism, which showed that a short-term nutritional supplementation in sheep may be associated with liver metabolism by PPAR signaling pathway, AMPK signaling and Insulin signaling pathway. Importantly, PDK4 and G0S2 may be core essential genes and play an important role in these pathways. All these results might be contributed to detect related genes associated with energy metabolism in the liver tissues of sheep. Overall, the findings presented here provide the first evidence for key candidate genes affecting liver function.