Deciphering the Regulatory Network of Tail Fat Deposition in Large- and Small-Tailed Han Sheep Through Transcriptome and MicroRNAome Profiling

Tail fat deposition constitutes a distinctive adaptive phenotype in sheep. The Large-tailed Han (LTH) and Small-tailed Han (STH) breeds display pronounced divergence in tail fat storage, offering an ideal model for elucidating lipid metabolism regulation. Integrated sRNA-Seq and RNA-Seq analysis identified 521 differentially expressed genes and 144 miRNAs, which were significantly enriched in lipid metabolism pathways, including fatty acid metabolism and PPAR signaling. Key candidate genes (<i>ADIRF</i>, <i>LPL</i>, <i>ACSL5</i>) were highlighted as pivotal regulators. Additionally, 23 miRNA-mRNA regulatory networks were constructed, revealing complex interaction patterns from 'one-to-one' to 'many-to-one' relationships. For example, six miRNAs collectively targeted <i>LTA4H</i>. Collectively, this study advances understanding of the genetic network underlying tail fat deposition and provides candidate targets for modulating lipid metabolism. Functional validation is warranted to delineate causal mechanisms.