Abstract
BackgroundBreast milk contains complex nutrients and facilitates the maturation of various biological systems in infants. Exosomes, membranous vesicles of endocytic origin found in different body fluids such as milk, can mediate intercellular communication. We hypothesized that microRNAs (miRNAs), a class of non-coding small RNAs of 18–25 nt which are known to be packaged in exosomes of human, bovine and porcine milk, may play important roles in the development of piglets.ResultsIn this study, exosomes of approximately 100 nm in diameter were isolated from porcine milk through serial centrifugation and ultracentrifugation procedures. Total RNA was extracted from exosomes, and 5S ribosomal RNA was found to be the major RNA component. Solexa sequencing showed a total of 491 miRNAs, including 176 known miRNAs and 315 novel mature miRNAs (representing 366 pre-miRNAs), which were distributed among 30 clusters and 35 families, and two predicted novel miRNAs were verified targeting 3’UTR of IGF-1R by luciferase assay. Interestingly, we observed that three miRNAs (ssc-let-7e, ssc-miR-27a, and ssc-miR-30a) could be generated from miRNA-offset RNAs (moRNAs). The top 10 miRNAs accounted for 74.5% (67,154 counts) of total counts, which were predicted to target 2,333 genes by RNAhybrid software. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses using DAVID bioinformatics resources indicated that the identified miRNAs targeted genes enriched in transcription, immunity and metabolism processes, and 14 of the top 20 miRNAs possibly participate in regulation of the IgA immune network.ConclusionsOur findings suggest that porcine milk exosomes contain a large number of miRNAs, which potentially play an important role in information transfer from sow milk to piglets. The predicted miRNAs of porcine milk exosomes in this study provide a basis for future biochemical and biophysical function studies.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-100) contains supplementary material, which is available to authorized users.
Highlights
Breast milk contains complex nutrients and facilitates the maturation of various biological systems in infants
Approximately round-shaped porcine milk exosomes with diameters of ~50-100 nm were observed by Transmission electron microscopy (TEM), showing a greater density at the center than at the boundary (Figure 2A, B)
The extracted RNA could not be digested by DNase I, while it could be degraded by RNase (Figure 3A). These results demonstrated that the porcine milk exosomes contained RNA
Summary
Breast milk contains complex nutrients and facilitates the maturation of various biological systems in infants. We hypothesized that microRNAs (miRNAs), a class of non-coding small RNAs of 18–25 nt which are known to be packaged in exosomes of human, bovine and porcine milk, may play important roles in the development of piglets. Exosomes are small (30–100 nm) membrane vesicles of endocytic origin that are released into the extracellular environment upon fusion of multivesicular bodies (MVB) with the plasma membrane [5]. Several studies have suggested that exosomes, which contain proteins, mRNA and microRNA (miRNA), stimulate and transfer surface receptors to target cells [21,22,23], as well as serve as novel vehicles for genetic exchange between cells [24]. Porcine milk was reported to contain 180 pre-miRNAs, including 140 known and 40 novel porcine pre-miRNAs, altogether encoding 237 mature miRNAs [29]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
