Comparative Transcriptome Analysis of MicroRNAs in Newborn and Adult Porcine Skeletal Muscles

The domestic pig (Sus scrofa), an important livestock in meat industry, is a suitable model organism for studying the skeletal muscle development that is complex and sophisticated biological and metabolic processes critically controlled by microRNAs (miRNAs) at the post-transcriptional level. To identify the miRNAs that regulate muscle phenotype in different breeds of pigs and explore the complex mechanism underlying this regulation, Solexa sequencing technology was used to compare the miRNA transcriptome profile in the longissimus dorsi muscle from the Bama mini-pigs with that from the Landrace pigs at the ages of day 1 (newborn) and 180 (adult). We identified 292 known miRNAs and 86 putative novel miRNAs in skeletal muscle, with 9 novel miRNAs identified using RT-PCR and sequencing. Moreover, 10 miRNAs were confirmed by qRT-PCR to manifest increased expression, in concordance with our sequencing results. Target genes of miRNAs that showed significantly differential expression were functionally categorized by using the Gene Ontology and the Kyoto Encyclopedia of Genes. The results suggested that the differences in the expression of these miRNAs might reflect the differences in the muscle phenotype and meat quality traits between the Bama mini-pigs and Landrace pigs. Our results provide us with insights into muscle biology for further improvement of porcine meat quality.