Identification of key microRNAs affecting drip loss in porcine longissimus dorsi by RNA-Seq.

MicroRNAs (miRNAs) are a class of ~22-nt non-coding small RNA that play an important role in various metabolic processes, mainly through suppressing the expression of protein coding genes at post-transcriptional level. Drip loss (DL) is one of the most important meat quality traits affecting the end product yield and quality of pork. To date, the underlying regulatory factors involved in DL trait are still incompletely understood. In the present study, we constructed two small RNA libraries with longissimus dorsi muscles from the higher DL (WJJ-H group) and the lower DL (WJJ-L group) individuals, and applied RNA-Seq technology to identify the differentially expressed miRNAs between the two extreme phenotypes of DL groups. A total of 184 and 176 porcine known miRNAs were detected from WJJ-H and WJJ-L groups, respectively. Moreover, 73 differentially expressed miRNAs were identified between two groups, of which 40 were up-regulated and 33 were down-regulated. In addition, 133 and 140 novel potential miRNAs were predicted from WJJ-H and WJJ-L groups, respectively. Notably, we preliminary confirmed that both miRNA-499 and miRNA-22 were potential candidates influencing DL trait by their expression pattern analysis. Overall, our data enhance the knowledge of porcine skeletal muscle miRNAs, and provide foundation for clarifying the miRNA regulatory mechanisms involved in DL trait.