title: Human villous trophoblasts express and secrete placenta-specific microRNAs into maternal circulation via exosomes.
abstract: In this study, we performed small RNA library sequencing using human placental tissues to identify placenta-specific miRNAs. We also tested the hypothesis that human chorionic villi could secrete miRNAs extracellularly via exosomes, which in turn enter into maternal circulation. By small RNA library sequencing, most placenta-specific miRNAs (e.g., MIR517A) were linked to a miRNA cluster on chromosome 19. The miRNA cluster genes were differentially expressed in placental development. Subsequent validation by real-time PCR and in situ hybridization revealed that villous trophoblasts express placenta-specific miRNAs. The analysis of small RNA libraries from the blood plasma showed that the placenta-specific miRNAs are abundant in the plasma of pregnant women. By real-time PCR, we confirmed the rapid clearance of the placenta-specific miRNAs from the plasma after delivery, indicating that such miRNAs enter into maternal circulation. By using the trophoblast cell line BeWo in culture, we demonstrated that miRNAs are indeed extracellularly released via exosomes. Taken together, our findings suggest that miRNAs are exported from the human placental syncytiotrophoblast into maternal circulation, where they could target maternal tissues. Finally, to address the biological functions of placenta-specific miRNAs, we performed a proteome analysis of BeWo cells transfected with MIR517A. Bioinformatic analysis suggests that this miRNA is possibly involved in tumor necrosis factor-mediated signaling. Our data provide important insights into miRNA biology of the human placenta.
authors.affiliation: Departments of Molecular Medicine and Anatomy, Obstetrics and Gynecology, and Biochemistry and Molecular Biology, Nippon Medical School, Tokyo, Japan.
authors.forename: Shan-Shun
authors.initials: SS
authors.lastname: Luo
authors.forename: Osamu
authors.initials: O
authors.lastname: Ishibashi
authors.forename: Gen
authors.initials: G
authors.lastname: Ishikawa
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Akira
authors.initials: A
authors.lastname: Katayama
authors.forename: Takuya
authors.initials: T
authors.lastname: Mishima
authors.forename: Takami
authors.initials: T
authors.lastname: Takizawa
authors.forename: Takako
authors.initials: T
authors.lastname: Shigihara
authors.forename: Tadashi
authors.initials: T
authors.lastname: Goto
authors.forename: Akio
authors.initials: A
authors.lastname: Izumi
authors.forename: Akihide
authors.initials: A
authors.lastname: Ohkuchi
authors.forename: Shigeki
authors.initials: S
authors.lastname: Matsubara
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Takeshita
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Takizawa
mesh_terms: D002460:Cell Line; D002824:Chorionic Villi / Q000378:metabolism*; D055354:Exosomes / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D017403:In Situ Hybridization; D035683:MicroRNAs / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011247:Pregnancy / Q000097:blood*; D040901:Proteomics; D017423:Sequence Analysis, RNA; D014327:Trophoblasts / Q000378:metabolism*
chemical_list: C546349:MIRN517 microRNA, human; D035683:MicroRNAs