title: Time-dependent expression profiles of microRNAs and mRNAs in rat milk whey.
abstract: 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.
authors.affiliation: Nutritional Science Institute, Morinaga Milk Industry Co., Ltd., Zama, Kanagawa, Japan.
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Izumi
authors.affiliation: Division of Molecular and Cellular Medicine, National Cancer Center Research Institute, Chuo-ku, Tokyo, Japan.
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Kosaka
authors.affiliation: Nutritional Science Institute, Morinaga Milk Industry Co., Ltd., Zama, Kanagawa, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Shimizu
authors.affiliation: Nutritional Science Institute, Morinaga Milk Industry Co., Ltd., Zama, Kanagawa, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Sekine
authors.affiliation: Division of Molecular and Cellular Medicine, National Cancer Center Research Institute, Chuo-ku, Tokyo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ochiya
authors.affiliation: Nutritional Science Institute, Morinaga Milk Industry Co., Ltd., Zama, Kanagawa, Japan.
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Takase
mesh_terms: D000818:Animals; D005260:Female; D020869:Gene Expression Profiling; D035683:MicroRNAs / Q000235:genetics*; D008892:Milk / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D013997:Time Factors
chemical_list: D035683:MicroRNAs; D012333:RNA, Messenger