Expression profile analysis of microRNAs during hair follicle development in the sheep foetus

MicroRNAs (miRNAs) regulate the development and growth cycle of hair follicles (HFs). The molecular mechanism by which miRNAs determine the development of HFs in the sheep foetus remains elusive. In this study, the expression profiles of miRNAs at 11 development periods (45, 55, 65, 75, 85, 95, 105, 115, 125, 135 and 145 d) in sheep foetus skin were analysed by high-throughput sequencing and bioinformatics analysis. A total of 72 conserved miRNAs, 44 novel miRNAs and 32 known miRNAs were significantly differentially expressed. qRT-PCR results for 18 miRNAs were consistent with the sequencing data. 85 d of foetal development was the starting point for secondary hair follicle (SF) development according to tissue morphology and cluster analysis. In SF development, the prolactin signalling pathway and platelet activation played important roles, and 10 miRNAs were potential candidate miRNAs in SF initiation. During 85d fetal development, 19 miRNAs were significantly up-regulated and 18 miRNAs were significantly down-regulated in initiation of secondary hair follicle growth

微小RNA（miRNAs）可调控毛囊（HFs）的发育与生长周期。目前，关于miRNAs调控绵羊胎儿毛囊发育的分子机制仍有待阐明。本研究通过高通量测序与生物信息学分析，对绵羊胎儿皮肤中11个发育时期（45、55、65、75、85、95、105、115、125、135及145日龄）的miRNAs表达谱进行了分析。共计72种保守型miRNAs、44种新发现miRNAs及32种已知miRNAs呈现显著差异表达。针对18种miRNAs的实时定量逆转录PCR（qRT-PCR）检测结果与测序数据一致。结合组织形态学观察与聚类分析结果可知，胎儿发育至85日龄为次级毛囊（SF）发育的起始节点。在次级毛囊发育过程中，催乳素信号通路与血小板活化发挥了关键作用，另有10种miRNAs可作为次级毛囊起始发育的潜在候选miRNAs。在胎儿发育至85日龄阶段，次级毛囊生长起始过程中有19种miRNAs显著上调，18种miRNAs显著下调。