Identification And Expression Of MiRNAs From Chicken Adipose Tissue And Skeletal Muscle

microRNAs(miRNAs) are a class of～22 nt small noncoding RNAs. They exist extensively in various organisms, negatively regulate gene expression by translational repression and degradation of target mRNAs. miRNAs are involved in many bioprocesses, including proliferation, differentiation, apoptosis and development.In this study, we constructed the cDNA libraries of small RNAs from 4 week chicken's adipose tissue and skeletal muscle. In the adipose library 44(16 varieties) were chicken miRNAs published, 39(5 varieties) were miRNAs homolog to other species. In the skeletal muscle library 81(27 varieties) were chicken miRNAs published, 31(4 varieties) were miRNAs homolog to other species. By further analysis, 11(9 varieties) potential new miRNAs were predicted in adipose, 7(4 varieties) potential new miRNAs were predicted in skeletal muscle. By location of various sequenced miRNAs in chicken genome, 5 miRNA gene clusters were found. Among the 5 miRNA gene clusters, 4 clusters have 2 miRNA genes respectively, 1 cluster has 4 miRNA genes. The sequence polymorphism was revealed by sequence alignment of the obtained miRNAs.Based on the bioinformatics method, 192 potential target genes were predicted in 250 expression genes in adipose, 216 potential target genes were predicted in 250 expression genes in skeletal muscle by using miRNA target prediction software miRanda and TargetScan. The interaction between miRNAs and their target genes was analyzed. These results establish a basis for further research on miRNA target genes in chicken adipose and skeletal muscle.The expression level of 10 miRNAs in 12 chicken tissues were detected using stem-loop RT and TaqMan real-time fluorescence quantitative PCR. gga-miR-133a and gga-miR-1a are expressed specifically in muscle. They may play an important role in growth and development of chicken muscle. gga-miR-122 has the highest expression level in liver and a low expression level in adipose. It may be involved in fatty acids metabolism and growth and development of chicken adipose. gga-miR-22, gga-miR-199, miR-23a and miR-145 has a high expression level in heart and muscular stomach and a very low expression level in skeletal muscle. They may play different roles in different type of muscle. gga-miR-126, gga-miR-200b and miR-191 has very low expression level in skeletal muscle and adipose. They may play no roles in the two tissues.