Transcriptome Comparison Reveals the Difference in Liver Fat Metabolism between Different Sheep Breeds

Area of Science:

• Comparative genomics
• Animal physiology
• Biochemistry

Background:

• Hu sheep and Tibetan sheep exhibit distinct morphological traits and environmental adaptations.
• The liver is central to fatty acid (FA) metabolism, influencing uptake, esterification, oxidation, and secretion.
• High-altitude and arid environments significantly impact liver metabolic processes.

Purpose of the Study:

• To characterize differences in liver fat metabolism between Hu sheep and Tibetan sheep using RNA-sequencing.
• To identify differentially expressed genes (DEGs) and enriched pathways related to fat metabolism.
• To investigate the role of specific genes in adaptive thermogenesis in Tibetan sheep.

Main Methods:

• RNA-sequencing (RNA-seq) to compare gene expression profiles in the livers of Hu sheep and Tibetan sheep.
• Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis to identify significantly affected biological pathways.
• Quantitative real-time PCR (qRT-PCR) and Western blot analysis to validate mRNA and protein expression levels of key genes.

Main Results:

• Identified 1179 differentially expressed genes (DEGs), including 25 fat-metabolism-related genes.
• Enriched pathways included proteasome, glutamatergic synapse, oxidative phosphorylation, and notably, thermogenesis.
• Genes like ACSL1, CPT1A, and FGF21, involved in FA oxidation, showed significantly higher mRNA and protein expression in Tibetan sheep livers.

Conclusions:

• Tibetan sheep livers exhibit a greater capacity for fatty acid oxidation compared to Hu sheep livers.
• Upregulated fat-metabolism genes in the thermogenesis pathway are linked to plateau-adaptive thermogenesis in Tibetan sheep.
• Liver and fat-metabolism-related genes play a crucial role in the adaptive thermogenesis of Tibetan sheep.