Integrated mRNA and miRNA Analysis Reveals Layer-Specific Mechanisms of Antler Yield Variation in Sika Deer

Antlers exhibit exceptionally rapid growth, representing a rare biological phenomenon among mammals. In addition to their scientific significance, antlers are widely used in traditional medicine, and their yield directly impacts the economic efficiency of the deer farming industry. However, antler yield varies substantially among individuals, and the molecular mechanisms underlying this variation remain poorly understood. This study aimed to elucidate the transcriptomic and post-transcriptional mechanisms underlying antler yield variation by comparing gene and miRNA expression profiles across four distinct antler tissue layers-dermis (D), reserve mesenchyme (RM), pre-cartilage (PC), and cartilage (C)-in sika deer with different yields. RNA-seq and miRNA-seq were performed, followed by differential expression, GO and KEGG pathway enrichment, and miRNA-mRNA co-expression network analyses. Our results reveal layer-specific expression patterns and key regulatory genes and miRNAs associated with proliferation, chondrogenesis, angiogenesis, and mineralization. In particular, genes such as FBP2, TPT1, TFRC, ZEB1, and PHOSPHO1 were upregulated in high-yield deer across specific tissue layers, while NFATC2 was downregulated in these high-yield deer. Additionally, miRNAs such as miR-140, miR-296-3p, and let-7e exhibited layer-specific expression patterns linked to growth and differentiation. Our miRNA-mRNA regulatory network analysis highlighted significant interactions, particularly miR-296-3p-PHOSPHO1 and miR-296-3p-FBP2, as key regulators of antler growth. Enrichment of PI3K-Akt and TGF-β signaling pathways further suggests their involvement in promoting chondrogenesis and ossification. These findings provide novel insights into the molecular basis of antler growth and yield, which may inform future strategies for selective breeding in deer farming.