The Study Of Expression Of MiNRAs In Wool Follicle During Different Development Phases

Sheep is important material for living and producting for farmers and herdsmen in Tibet. The sheep industry occupies an important position in animal husbandry. Threre are about39.45million Livestocks in Tibet in2009, and25.52of them are sheep. It is about64.7%of the number of total livestocks. Tibet is the third province which has the largest number of sheep in China. Wool and mutton quality are important economic traits of tibetan sheep. The wool is the fiber derived from the tissues called wool follicle. The wool follicle development process could be divided into anagen, catagen and telogen3phases. So understanding the molecular mechanism of wool follicle development is an important basis of improveing the quality of wool.MicroRNAs (miRNAs) are a class of noncoding RNAs which could regulate gene expression at the posttranscriptional level by bongding the3'UTR of mRNAs. There are increasing evidences to show that miRNAs play important roles in cell proliferation and differentiation; however, few studies have focused on miRNAs in wool follicle. Wool follicle is one of the most important economic trait of sheep. Wool is the fibber derived from wool follicle. So understanding the molecular mechanism of wool follicle development is an important basis of improveing the quality of wool. In this study, we used high-throughput sequencing technology to identify miRNAs which expressed in anagen, catagen and telogen in wool follicle and analysed the sequencing data by bioinformatics. also we predicted the target genes of miRNA-31, miRNA-184and miRNA-205. The results show that:1. By performming small RNA sequencing to wool follicle during3different phases, we identified406miRNAs all together. Among the406miRNAs,5of them are known miRNAs in sheep database, and the other401miRNAs are novel. Among the401novel miRNAs,320of them are homologous with other species and the other86are totally novel. The results can enrich the information of database of miRNAs in sheep. 2. We study the distribution of of miRNAs expressed in wool follicle on genome. We found that the number of miRNA which are located on chromosome11is much high than others. That suggest that chromosome11is important for wool follicle.3.We found102differential expressed miRNA in wool follicle among3phases by bioinformatic analysis, and44of them are phase specific expressed. The number of phase specific expressed miRNAs in wool follicle are10in anagen,27in catagen and7in Tolegen. It suggest that these miRNAs might play important role in wool follicle development cycle,4. We detected the expression of microRNA-31in hair follicle tissue of Tibetan sheep at three different developmental stages by QPCR. The precursor of microRNA-31was predicted and the sequence of microRNA-31was mapped to genome of sheep. Furthermore two target genes of microRNA-31were predicted and verified by QPCR. The results of our study indicate that the expression of microRNA-31in hair follicle tissue shows decreasing trend from anagen to telogen., and the sequence of microRNA-31was located on chromosome2of sheep genome. Moreover KRT17probably was one of target genes of micro RNA-31.5. We detected the expression of miRNA-184and miRNA-205in hair follicle at three different developmental stages of sheep by QPCR. The precursors of these two microRNAs was predicted and the sequences were mapped to genome of sheep. Furthermore target genes and pathways of these two microRNAs were predicted. The results of our study indicate that the expression of miRNA-184in hair follicle tissue shows increasing trend from anagen to telogen. But miRNA-205increase from anagen to catagen, and then decrease from catagen to telogen. The expression of miRNA-205was highest in catagen. We found miRNA-184and miRNA-205both expressed in many different tiusses. Moreover the candidate target genes of these two microRNAs were involved in15different pathways and miRNA-184and miRNA-205probably regulate the hair follicle development through Wnt signaling pathway. 6. We found that most of wool follicle of tibetan sheep are primary follicle in embryonic skin. However most of wool follcile are Secondary follcile in adult skin. The ratio of S/P is2.55. that suggest that tibetan sheep is one kind of coarse-wooled sheep.