MicroRNAomes Of Porcine Arterial And Venous Blood

MicroRNAs (miRNAs), a class of 18～24 nucleotide noncoding RNAs, regulate gene expression by specifically binding with target mRNA and are involved in a variety of cellular biological processes, such as cell proliferation, cell differentiation, cell metabolism, cell apoptosis and immune response. As the most important body fluid, blood plays an important role in many biological processes, and circulating miRNAs in the blood have been reported to be biomarkers for various physiological and pathological states. However, few studies have examined the porcine blood miRNAs, and the miRNA transcriptome of arterial blood has not, until now, been studied. In order to identify the the miRNA transcriptome of porcine blood and the different expression level of miRNAs between arterial blood and venous blood, we present the miRNA transcriptome of both blood using deep sequencing technology and validated with RT-PCR. The results showed that:(1) A total of 5.21 million (M) and 8.61M counts of sequenced sequences were obtained from pig arterial and venous blood, respectively. More than 78% of counts met the accepted criteria and were deemed as mappable reads, and the length distribution peaked at 21-23nt.(2) A total of 272 known miRNAs,52 conserved miRNAs and 281 putative new miRNAs were identified in both libraries. The top 20 unique miRNAs with the highest expression levels accounted for 85.35% and 84.75% of the total counts in arterial and venous blood, respectively.(3) Among the top 20 most abundant miRNAs,17 were present in both libraries. According to KEGG pathway annotation, the highly expressed miRNAs were implicated in erythropoiesis and angiogenesis.(4) After been tested by IDEG6 program, there were 57 significant differentially expressed miRNAs between arterial and venous blood (p< 0.001). And only five (miR-18a, miR-21, miR-99a, miR-144, and miR-7) and seven (miR-423, miR-16, miR-181a, miR-425, miR-151, miR-192, and miR-142) were significantly enriched in venous and arterial blood, respectively, meeting the 1.5-fold changes.(5) The bioinformatics analysis of the 12 different expressed miRNAs showed that the target genes of venous blood-enriched miRNAs were enriched in cell apoptosis and hypoxia induced process, however, the target genes of arterial blood-enriched miRNAs were strongly associated with immune response pathways.Our results provided new reference data of the porcine miRNAs and basic information for further investigation of the blood, and may help promote the further molecular diagnosis of blood.