Transcriptome Analysis of Adipose Tissues from Five Sheep Breeds Reveals Key Genes Involved in Fat Deposition

Area of Science:

• Genomics and Transcriptomics
• Animal Science
• Comparative Biology

Background:

• Sheep adipose tissue deposition, particularly tail fat, shows significant breed-specific variation impacting meat quality and adaptation.
• Understanding the transcriptomic basis of tail fat diversity is crucial for sheep breeding and understanding adaptive traits.

Purpose of the Study:

• To systematically compare transcriptional profiles across five adipose depots and five sheep breeds.
• To identify molecular mechanisms and key regulatory genes underlying fat deposition and tail phenotype divergence in sheep.

Main Methods:

• RNA-sequencing data from 250 samples across five adipose tissues and five sheep breeds were analyzed.
• Differential gene expression, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed.
• Breeds were phenotypically classified (fat-tailed, short fat-tailed, thin-tailed) for phenotype-specific pathway analysis.

Main Results:

• Subcutaneous and intermuscular fat showed the most transcriptional divergence; tail fat displayed conserved and phenotype-specific pathways.
• Fat-tailed breeds exhibited enrichment in mitochondrial oxidative phosphorylation and lipid biosynthesis pathways (e.g., TAFAZZIN, GPAM).
• Short fat-tailed breeds were characterized by extracellular matrix remodeling genes (e.g., MMP9, MMP12), while thin-tailed sheep lacked these pathways.

Conclusions:

• Distinct molecular mechanisms differentiate sheep tail fat phenotypes: metabolic efficiency in fat-tailed, ECM remodeling in short fat-tailed, and limited pathways in thin-tailed breeds.
• Identified candidate genes provide potential targets for molecular breeding strategies to enhance fat deposition and adaptive traits in sheep.