Time-dependent expression profiles of microRNAs and mRNAs in rat milk whey

• Published in: PloS one Vol. 9; no. 2; p. e88843
• Main Authors: Izumi, Hirohisa, Kosaka, Nobuyoshi, Shimizu, Takashi, Sekine, Kazunori, Ochiya, Takahiro, Takase, Mitsunori
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 12.02.2014; Public Library of Science (PLoS)
• Subjects: Animals; Biology; Biosynthesis; Cancer; Cell cycle; Colostrum; Cytokines; DNA microarrays; Female; Gene expression; Gene Expression Profiling; Hormones; In vivo methods and tests; Laboratory animals; Medicine; Messenger RNA; MicroRNA; MicroRNAs; MicroRNAs - genetics; Milk; Milk - metabolism; miRNA; Neonates; Newborn babies; Oligonucleotide Array Sequence Analysis; Polymerase Chain Reaction; Postpartum; Pregnancy; Proteins; Rats; Ribonucleic acid; RNA; RNA, Messenger - genetics; Rodents; Studies; Time dependence; Time Factors; Veterinary Science; Whey
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0088843

Functional RNAs, such as microRNA (miRNA) and mRNA, are present in milk, but their roles are unknown. To clarify the roles of milk RNAs, further studies using experimental animals such as rats are needed. However, it is unclear whether rat milk also contains functional RNAs and what their time dependent expression profiles are. Thus, we prepared total RNA from whey isolated from rat milk collected on days 2, 9, and 16 postpartum and analyzed using microarrays and quantitative PCR. The concentration of RNA in colostrum whey (day 2) was markedly higher than that in mature milk whey (days 9 and 16). Microarray analysis detected 161 miRNAs and 10,948 mRNA transcripts. Most of the miRNAs and mRNA transcripts were common to all tested milks. Finally, we selected some immune- and development-related miRNAs and mRNAs, and analysed them by quantitative PCR (in equal sample volumes) to determine their time-dependent changes in expression in detail. Some were significantly more highly expressed in colostrum whey than in mature milk whey, but some were expressed equally. And mRNA expression levels of some cytokines and hormones did not reflect the protein levels. It is still unknown whether RNAs in milk play biological roles in neonates. However, our data will help guide future in vivo studies using experimental animals such as rats.