Identificatioil Of Food-derived Exogenous Plant MiRNAs In Swine

microRNAs (miRNAs), a class of22-nucleotide-long noncoding RNAs, emerge as key post-transcriptional regulators of gene expression in eukaryotic organisms and involve in a variety of cellular processes, such as cell proliferation, cell differentiation and apoptosis. It has been estimated that miRNAs can regulate the expression of more about30%of the human genes. MIR168a is a kind of plant miRNAs which widely present in food crops such as rice, corn and soybeans. At present, Nanjing University Professor Zhang Chenyu provided direct evidence that food-derived plant miRNAs can be digested and absorbed by human,mouse,cow,horse and other animals,in addition, MIR168a could bind to the human/mouse low-density lipoprotein receptor adapter protein1(LDLRAP1) mRNA, inhibit LDLRAP1expression in liver,and consequently decrease LDL removal from mouse plasma. In addition, a large number of reports indicated that transgenic plants expressing interfering RNA can effectively reduce insect damage, these studies provide strong evidence for the regulation of cross-species of small RNA molecules. Sus scrofa (pig or swine) as an important agricultural economic animal and biomedical research model, which feed is most of plant feed such as corn and soybeans, then whether the existence of exogenous plant miRNAs in swine tissues? Our study first used swine as the experimental animal and detected whether there is genuine plant miRNA in sow serum and tissues and analysised the concentration of plant miRNAs using fluorescence quantitative method. Our results indicate that:1. By using high-throughput sequencing, we obtained13.31M raw data and identified135known maize miRNAs in fresh corn.2. We detected miRNAs concentration of4differently-treated corns by RT-PCR. According to the average concentration of miRNAs, the sequence can be arranged like this:fresh corn (529.40fmol/g)> steamed corn (190.20fmol/g)> dried corn (102.95fmol/g)> puffed corn (17.71fmol/g).3. We detected18exogenous maize miRNAs concentration in swine serum and tissues by RT-PCR, MIR164a.、IR390a、MIR319a、MIR167e and MIR408a showed high considerable levels. These five exogenous miRNAs treated with sodium periodate, after oxidation treatment the exogenous miRNAs still had a relatively high level, while endogenous animal miRNAs can not be detected in the tissues, thus prove them to be genuine plant miRNAs. In addition, only mature plant miRNAs were detected in swine serum and tissues while these pre-miRNAs were not.4. In swine serum, the concentration of plant miRNAs ranges from0.01fM to0.15fM, almost one-tenth of that of endogenous miR-16. In swine tissues, the concentration of plant miRNAs ranges from0.001fmol/g to0.5fmol/g, almost one thousandth of that of endogenous miR-16. Besides, plant miRNAs can be also detect in serum exosome.These results showed that the exogenous plant miRNA can enter the body of the animal, and exosome may be a way of protection. Our results provided basic information for further investigation of the cross-kingdom regulation mechanism of food-derived miRNA.