title: HLA-G expression is regulated by miR-365 in trophoblasts under hypoxic conditions.
abstract: Hypoxia occurs in the first trimester of placental development and is implicated in the regulation of trophoblast differentiation. Prolonged hypoxic conditions in the placenta are related to the development of preeclampsia. MicroRNAs (miRNAs) are noncoding, single-stranded RNAs that modulate gene expression by targeting messenger RNA. We hypothesized that, under hypoxic conditions, trophoblasts may have a unique miRNA profile that may play a critical role in placental development.
  
  
  
  Total RNA was extracted from human trophoblast, HChEpC1b, exposed to normoxia (20% O2) or hypoxia (2% O2) for 24 h, and the miRNA expression profiles were investigated using a microRNA array. Several differential miRNAs were selected and validated using real-time reverse transcription PCR. We identified potential targets of these miRNAs using in silico analysis. We confirmed a potential target protein by western blot analysis and luciferase assays.
  
  
  
  The expression of miR-365 was significantly upregulated under hypoxic conditions. In silico analysis showed that miR-365 targeted human leukocyte antigen (HLA)-G. Both hypoxic conditions and overexpression of miR-365 inhibited the expression of HLA-G proteins. The overexpression of miR-365 also decreased the activity of the luciferase reporter containing the 3'-untranslated region (UTR) of HLA-G with the predicted miR-365-binding site.
  
  
  
  HLA-G is a non-classical HLA class-Ib molecule that is expressed mainly in extravillous trophoblasts and which plays a key role in maintaining immune tolerance at the maternal-fetal interface. Our results indicate that miR-365 targets the HLA-G 3' UTR to repress its expression. The expression of miR-365 may play an important role in human placental development and in immunoprotection of the semiallogenic embryo.
authors: Department of Obstetrics and Gynecology, Tokyo Medical University, Tokyo, Japan.
authors: Asako
authors: A
authors: Mori
authors: Department of Obstetrics and Gynecology, Tokyo Medical University, Tokyo, Japan. Electronic address: nishih@tokyo-med.ac.jp.
authors: Hirotaka
authors: H
authors: Nishi
authors: Department of Obstetrics and Gynecology, Tokyo Medical University, Tokyo, Japan.
authors: Toru
authors: T
authors: Sasaki
authors: Department of Obstetrics and Gynecology, Tokyo Medical University, Tokyo, Japan.
authors: Yuzo
authors: Y
authors: Nagamitsu
authors: Department of Obstetrics and Gynecology, The Jikei University School of Medicine, Tokyo, Japan.
authors: Rie
authors: R
authors: Kawaguchi
authors: Department of Obstetrics and Gynecology, The Jikei University School of Medicine, Tokyo, Japan.
authors: Aikou
authors: A
authors: Okamoto
authors: Department of Molecular Pathology, Tokyo Medical University, Tokyo, Japan.
authors: Masahiko
authors: M
authors: Kuroda
authors: Department of Obstetrics and Gynecology, Tokyo Medical University, Tokyo, Japan.
authors: Keiichi
authors: K
authors: Isaka
mesh_terms: D020413:3' Untranslated Regions; D002450:Cell Communication; D015687:Cell Hypoxia / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation; D059951:HLA-G Antigens / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D010920:Placenta / Q000166:cytology / Q000378:metabolism; D010929:Placentation / Q000502:physiology*; D011247:Pregnancy; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism*
chemical_list: D020413:3' Untranslated Regions; D059951:HLA-G Antigens; C546819:MIRN365 microRNA, human; D035683:MicroRNAs
keywords: HLA-G; Hypoxia; Placenta; miR-365; miRNA