title: DNA methylation-associated repression of MEST/PEG1 expression contributes to the invasion of extravillous trophoblast cells.
abstract: The invasion of extravillous cytotrophoblasts (EVTs) into the maternal uterine decidua and vasculature is critical for human placenta development and pregnancy maintenance. The imprinted gene MEST/PEG1 has been implicated in trophoblast development; however, the role of MEST in EVT invasion and the accompanying early pregnancy complications are not fully understood.
  
  
  
  Western blot, immunofluorescence and immunohistochemistry were used to detect MEST protein expression and localization by using antibodies recognize 2 reported isoforms. Specific small interference RNA (siRNA) targeting both of the MEST isoforms was applied to silence MEST expression in extravillous explants and HTR8/SVneo cells. Cell invasion and migration were assessed using the Matrigel invasion, Transwell migration assay and the xCELLigence system. Promoter DNA methylation was examined using bisulfite-sequencing polymerase chain reaction (BSP).
  
  
  
  MEST protein was highly expressed in EVTs in the first trimester placenta and in the invasive EVT cell lines HTR-8/Svneo and HPT-8. Weak MEST expression was found in cytotrophoblasts (CTBs) and the choriocarcinoma-derived CTB cell line JEG-3. The specific siRNA knockdown of MEST expression significantly reduced HTR-8/Svneo cell invasion and migration as well as extravillous explant outgrowth, which were associated with the downregulation of Twist, N-cadherin and Vimentin. Decreased MEST protein expression with isoform 2 promoter hypermethylation was observed in the placentas of missed abortions, suggesting a possible pathological mechanism of missed abortion.
  
  
  
  Suppressed expression of MEST was associated with its isoform 2 promoter hypermethylation ex vivo placenta tissues and in vitro cultured EVT cell lines. The present results provide a possible pathological mechanism of missed abortion.
authors.affiliation: Department of Obstetrics and Gynecology, The First Affiliated Hospital, Chongqing Medical University, Chongqing, 400016, China; Canada-China-New Zealand Joint Laboratory of Maternal and Fetal Medicine, Chongqing Medical University, Chongqing, 400016, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Peng
authors.affiliation: Department of Obstetrics and Gynecology, The First Affiliated Hospital, Chongqing Medical University, Chongqing, 400016, China; Canada-China-New Zealand Joint Laboratory of Maternal and Fetal Medicine, Chongqing Medical University, Chongqing, 400016, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Obstetrics and Gynecology, The First Affiliated Hospital, Chongqing Medical University, Chongqing, 400016, China; Canada-China-New Zealand Joint Laboratory of Maternal and Fetal Medicine, Chongqing Medical University, Chongqing, 400016, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Luo
authors.affiliation: Department of Obstetrics and Gynecology, The First Affiliated Hospital, Chongqing Medical University, Chongqing, 400016, China; Canada-China-New Zealand Joint Laboratory of Maternal and Fetal Medicine, Chongqing Medical University, Chongqing, 400016, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Shan
authors.affiliation: Laboratory of Reproductive Biology, School of Public Health and Management, Chongqing Medical University, Chongqing, 400016, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Lan
authors.affiliation: Departments of Obstetrics and Gynecology, Pediatrics and Physiology, University of Alberta, Edmonton, AB T6G 2S2, Canada; Canada-China-New Zealand Joint Laboratory of Maternal and Fetal Medicine, Chongqing Medical University, Chongqing, 400016, China.
authors.forename: David
authors.initials: D
authors.lastname: Olson
authors.affiliation: Department of Obstetrics and Gynecology, The First Affiliated Hospital, Chongqing Medical University, Chongqing, 400016, China; Canada-China-New Zealand Joint Laboratory of Maternal and Fetal Medicine, Chongqing Medical University, Chongqing, 400016, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Laboratory of Reproductive Biology, School of Public Health and Management, Chongqing Medical University, Chongqing, 400016, China; Canada-China-New Zealand Joint Laboratory of Maternal and Fetal Medicine, Chongqing Medical University, Chongqing, 400016, China. Electronic address: dingyb@gmail.com.
authors.forename: Yu-Bin
authors.initials: YB
authors.lastname: Ding
authors.affiliation: Department of Obstetrics and Gynecology, The First Affiliated Hospital, Chongqing Medical University, Chongqing, 400016, China; Canada-China-New Zealand Joint Laboratory of Maternal and Fetal Medicine, Chongqing Medical University, Chongqing, 400016, China. Electronic address: qihongbocq@gmail.com.
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: Qi
mesh_terms: D000030:Abortion, Missed / Q000378:metabolism*; D001483:Base Sequence; D015820:Cadherins / Q000378:metabolism; D019175:DNA Methylation; D005260:Female; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000378:metabolism*; D014327:Trophoblasts / Q000378:metabolism*; D014746:Vimentin / Q000378:metabolism
chemical_list: D015820:Cadherins; D011506:Proteins; D014746:Vimentin; C103637:mesoderm specific transcript protein
keywords: DNA methylation; MEST/PEG1; Missed abortion; Trophoblast