Identification And Differences Of MicroRNA Transcriptomes Between Cardiac Muscle And Skeletal Muscles In Porcine

MicroRNAs (miRNAs) are non-coding RNAs, approximately 22 nucleotides (nt) in length, which negatively regulate the expression of target genes. Compelling evidences have demonstrated the important roles of miRNAs in muscle proliferation, differentiation and development processes. Cardiac muscle and skeletal muscle (longissimus dorsi muscle and psoas major muscle) are both striated muscles, but they perform different functions in vivo. Pigs (Sus scrofa) are of great value to animal husbandry and medical researches. Meanwhile, little is known about the differences of miRNA expression pattern between these distinct muscles. In this study, we applied Illumina deep sequencing approach to identify the miRNA transcriptomes of cardiac muscle, longissimus dorsi muscle and psoas major muscle and three sequencing libraries were constructed from three 210-day-old female pigs (Landrace). All results are as follows:1) A total of 56 M raw data was generated from three sequencing libriaries; of which 20.31 M (94.12%),15.87 M (95.48%) and 17.93 M (97.14%) were high-quality reads in cardiac muscle, longissimus dorsi muscle and psoas major muscle, respectively.2) In total,907 unique miRNAs were identified in three sequencing libraries. Of 441 co-expressed miRNAs,123 were differentially expressed (P< 10-6) by IDEG6 program calculation among the three libraries.3) By Hierarchical clustering analysis and Pearson’s correlations analysis, the expression patterns of differentially expressed miRNAs showed that longissimus dorsi muscle and psoas major muscle had a more similar expression pattern, while cardiac muscle and two skeletal muscles had a different expression pattern.4) Ranking analysis showed that top ten expressed miRNAs in cardiac muscle also highly expressed in longissimus dorsi muscle and psoas major muscle. Of these ten miRNAs, eight were differentially expressed (miR-143,-378,-1,-133a,-27b,-30e,-101 and let-7a) and six miRNAs (miR-143,-378,-27b,-30e,-101 and let-7a) were up-regulated (>1.5-fold change) in cardiac muscle compared to longissimus dorsi muscle and psoas major muscle simultaneously.5) GO and KEGG pathway analyses for the predicted target genes of the up-regulated six miRNAs showed that the targets of highly expressed miRNAs in cardiac muscle are mainly involved in insulin (n= 21, P< 0.01) and calcium (n= 25, P< 0.01) signaling pathways.6) Based on previous studies, we constructed miRNA-mRNA interaction networks involved in insulin and calcium signaling pathways of cardiac muscle during four muscle developmental stages (including 0 d,30 d,210 d and 7 years), which indicated the negative regulation relationship between miRNAs and mRNA, and the important differences between cardiac and skeletal muscles.In summary, all results provided the differences of miRNA expression patterns between cardiac muscle and skeletal muscles with distinct charicteristcs. These may promote the researches on muscle and muscle-related diseases in a certain degree.