Identification of the Genetic Basis for the Large-tailed Phenotypic Trait in Han Sheep Through Integrated mRNA and miRNA Analysis of Tail Fat Tissue Samples

Abstract Background: While evolution has led certain breeds of sheep to exhibit large tails composed of fatty tissue, the genetic basis for this fatty large-tailed phenotypic trait remains to be defined in breeds of Han sheep. Here, we employed a high-throughput sequencing approach to identify mRNAs and microRNAs (miRNAs) that were differentially expressed in tail fat tissue samples from large-tailed Han (LTH) and small-tailed Han (STH) sheep in order to identify key genetic determinants of the large-tailed phenotype.Results: In total, we identified 521 mRNAs (237 upregulated, 284 downregulated) and 14 miRNAs (6 upregulated, 8 downregulated) that were differentially expressed between these two sheep breeds. Predictive analytical database tools were subsequently utilized to identify 2,409 putative targets of these differentially expressed miRNAs (DEMs), including 65 which were among the list of differentially expressed genes (DEGs) identified in the present study. By specifically focusing on predicted DEM/DEG pairs with appropriate regulatory directionality, we identified DIRF, HSD17B12, LPL, APOBR, INSIGI, THRSP, ACSL5, FAAH, ACSS2, APOA1, ACLY, and ACSM3 through mRNA analyses and ACSL4, FTO, FGF8, IGF2, GNPDA2, LIPG, PRKAA2, ELOVL7, SOAT2, and SIRT1 through miRNA analyses as candidate genes which may regulate fat deposition and fatty acid metabolism in the adipose tissue from the tails of Han sheep. Conclusion: Together, our data provide insight into the potential genetic basis for the large-tailed phenotype of LTH sheep, suggesting that it may be attributable to specific DEMs and DEGs that regulate one another and thereby control lipid metabolism. These data provide a basis for future research regarding the role of these genes in ovine tail fat deposition, and offer preliminary perspectives on the molecular mechanisms governing the fatty large-tailed phenotype in LTH sheep.