Identification and characterization of long non-coding RNA in prenatal and postnatal skeletal muscle of sheep.

lncRNAs are a class of transcriptional RNA molecules of >200 nucleotides in length. However, the overall expression pattern and function of lncRNAs in sheep muscle is not clear. Here, we identified 1566 lncRNAs and 404 differentially expressed lncRNAs in sheep muscle from prenatal (110 days of fetus) and postnatal (2 to 3 years old of adult sheep) developmental stages by using RNA-seq technology. Several lncRNAs were identified by using RT-PCR and DNA sequencing. The expression levels of several lncRNAs were confirmed by qRT-PCR. We analyzed the effect of lncRNAs that act cis to the target genes. lncRNA targeting genes were involved in signaling pathways associated with growth and development of muscle by GO and KEGG enrichment analysis. Through our study, we provide a comprehensive expression profile of muscle lncRNAs in sheep, which provides valuable resources for further understanding genetic regulation of muscle growth and development from the perspective of lncRNA.

Expression profiles of circular RNAs in sheep skeletal muscle.

OBJECTIVE: Circular RNAs (circRNAs) are a newfound class of non-coding RNA in animals and plants. Recent studies have revealed that circRNAs play important roles in cell proliferation, differentiation, autophagy and apoptosis during development. However, there are few reports about muscle development-related circRNAs in livestock. METHODS: RNA sequencing analysis was employed to identify and annotate circRNAs from longissimus dorsi of sheep. Reverse transcription followed by real-time quantitative (q) polymerase chain reaction (PCR) analysis verified the presence of these circRNAs. Targetscan7.0 and miRanda were used to analyse the interaction of circRNA-microRNA (miRNA). To investigate the function of circRNAs, an experiment was conducted to perform enrichment analysis hosting genes of circRNAs using gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathways. RESULTS: About 75.5 million sequences were obtained from RNA libraries of sheep skeletal muscle. These sequences were mapped to 729 genes in the sheep reference genome. We identified 886 circRNAs, including numerous circular intronic RNAs and exonic circRNAs. Reverse transcription PCR (RT-PCR) and DNA sequencing analysis confirmed the presence of several circRNAs. Real-Time RT-PCR analysis exhibited resistance of sheep circRNAs to RNase R digestion. We found that many circRNAs interacted with muscle-specific miRNAs involved in growth and development of muscle, especially circ776. The GO and KEGG enrichment analysis showed that hosting genes of circRNAs was involved in muscle cell development and signaling pathway. CONCLUSION: The study provides comprehensive expression profiles of circRNAs in sheep skeletal muscle. Our study offers a large number of circRNAs to facilitate a better understanding of their roles in muscle growth. Meanwhile, we suggested that circ776 could be analyzed in future study.