Integrated miRNA-mRNA analysis reveals regulatory pathways underlying the curly fleece trait in Chinese tan sheep.

BACKGROUND: Tan sheep is an indigenous Chinese breed well known for its beautiful curly fleece. One prominent breed characteristic of this sheep breed is that the degree of curliness differs markedly between lambs and adults, but the molecular mechanisms regulating the shift are still not well understood. In this study, we identified 49 differentially expressed (DE) microRNAs (miRNAs) between Tan sheep at the two stages through miRNA-seq, and combined the data with that in our earlier Suppression Subtractive Hybridization cDNA (SSH) library study to elucidate the mechanisms underlying curly fleece formation.

RESULTS: Thirty-six potential miRNA-mRNA target pairs were identified using computational methods, including 25 DE miRNAs and 10 DE genes involved in the MAPK signaling pathway, steroid biosynthesis and metabolic pathways. With the differential expressions between lambs and adults confirmed by qRT-PCR, some miRNAs were already annotated in the genome, but some were novel miRNAs. Inhibition of KRT83 expression by miR-432 was confirmed by both gene knockdown with siRNA and overexpression, which was consistent with the miRNAs and targets prediction results.

CONCLUSION: Our study represents the comprehensive analysis of mRNA and miRNA in Tan sheep and offers detailed insight into the development of curly fleece as well as the potential mechanisms controlling curly hair formation in humans.