Human villous trophoblasts express and secrete placenta-specific microRNAs into maternal circulation via exosomes.
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.
Luo
Shan-Shun
SS
Departments of Molecular Medicine and Anatomy, Obstetrics and Gynecology, and Biochemistry and Molecular Biology, Nippon Medical School, Tokyo, Japan.
Ishibashi
Osamu
O
Ishikawa
Gen
G
Ishikawa
Tomoko
T
Katayama
Akira
A
Mishima
Takuya
T
Takizawa
Takami
T
Shigihara
Takako
T
Goto
Tadashi
T
Izumi
Akio
A
Ohkuchi
Akihide
A
Matsubara
Shigeki
S
Takeshita
Toshiyuki
T
Takizawa
Toshihiro
T
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*
C546349:MIRN517 microRNA, human; D035683:MicroRNAs