MicroRNA Expression Differences Under Different Treatments Of Mammalian Milk

Breast milk is the best natural food of human’s and other mammals’babies, it plays a very important role of systemic resistance to disease and local disease prevention for babies, and it is nutritionally balance, clean, convenient, helps digestion and absorption. Breast milk can also contribute to control the disease, so that it protect babies from infections, promote the rapid maturation of the infant immune system, help the baby resist bacterial and viral infection, and improve its ability to resist disease.MicroRNA (miRNA) is a class of endogenous approximately22nucleotide non-coding small RNA molecules regulating after gene transcription levels, they are widespread in a variety of eukaryotic body, they can degrade mRNA or inhibit their translation with the target mRNA complementary combination of the3’UTR (non-coding regions). These miRNAs play an important role in gene expression, individual organisms and development, metabolism and disease and other physiological processes.Human breast milk contains a large number of immune-related miRNAs, our laboratory also found that in pig milk, these miRNAs may enter through the milk to the babies’body and exercise their functions. But we all know that RNA can be degraded easily, then the stability of the miRNA is a matter of concern. So our experiment is to investigate the expression of pig milk, human breast milk and cow milk miRNAs before and after different treatments.The experiment results show that all of the endogenous miRNAs and exogenous miRNA were significant degraded (P<0.01), but degradation multiples of endogenous miRNAs far lower than the degradation multiples of exogenous miRNA. Pig milk endogenous genes degradation multiples is1.8to5.3, however the degradation multiples of exogenous gene is in13.2to5000.0; degradation of endogenous genes in human milk in multiples is2to12.5, and exogenous gene degradation multiples is in12.5to1111.1; cow milk endogenous genes degradation multiples is1.8to3.7, however the degradation multiples of exogenous gene is in30.3to500.0.These results indicate that pig milk, human milk and cow milk endogenous miRNA is more stable and greater resistance to harsh condition than exogenous miRNA. The result suggests that the miRNA in these three kinds of milk may be packaged in exosome or microvesicles for protecting, thus completing the miRNA transfer from mother to baby and transmission of information between cells to exercise its regulatory function.