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

## TL;DR

This study explores how genes and microRNAs control fat storage in sheep tails, identifying key regulators and networks that could help improve breeding strategies.

## Contribution

The study identifies novel miRNA–mRNA regulatory networks and candidate genes involved in tail fat deposition in sheep.

## Key findings

- Transcriptomic and microRNAome analysis revealed 521 differentially expressed genes and 144 miRNAs linked to lipid metabolism.
- Key genes like ADIRF, LPL, and ACSL5 were identified as pivotal regulators of tail fat deposition.
- 23 miRNA–mRNA regulatory networks were constructed, showing complex interactions including multiple miRNAs targeting LTA4H.

## Abstract

Fat tail development in sheep shows considerable phenotypic variation, but the genetic mechanisms remain unclear. To address this, we compared Large-tailed Han and Small-tailed Han sheep, which differ markedly in tail fat storage capacity. Transcriptomic profiling of tail adipose tissues identified 521 differentially expressed genes and 144 microRNAs. Functional enrichment analysis revealed significant involvement of lipid metabolism pathways. Further analysis pinpointed core genes regulating lipid synthesis and catabolism, and we constructed 23 miRNA–mRNA regulatory networks that showed coordinated regulation of fat storage-related genes by multiple miRNAs. These findings advance our understanding of the genetic mechanisms governing tail fat development and provide a foundation for future breeding strategies.

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 (ADIRF, LPL, ACSL5) 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 LTA4H. 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.