title: Glial cell missing-1 mediates over-expression of tissue inhibitor of metalloproteinase-4 in severe pre-eclamptic placental villi.
abstract: BACKGROUND
  Severe pre-eclampsia (sPE) causes significant maternal morbidity and intrauterine growth restriction as a result of severe placental dysfunction. Defects in the formation of both extra-villous and villous trophoblast are characteristic of this disease. The outer syncytiotrophoblast layer covering the placental villi develops syncytial knots and focal necrosis while reduced invasion of the extra-villous trophoblast results in a reduced maternal blood supply and ischemia of the placental villi. The transcription factor glial cell missing-1 (GCM1) regulates formation of both types of trophoblast. GCM1 expression is reduced in placental villi of women with sPE but the functional downstream consequences of reduced GCM1 expression are unknown.
  
  
  RESULTS
  In floating first trimester villous explants we demonstrated increased mRNA (2.5-fold, n = 12) and protein level (9.8-fold) of tissue inhibitor of metalloproteinase-4 (TIMP4) following repression of GCM1 (70 ± 7%) by small interfering-RNA, using RT-PCR and western blot, respectively. Similar increases in TIMP4 mRNA (4.2-fold, n = 7, P< 0.001 versus control) and protein levels were found following gene silencing of GCM1 in BeWo cells (<90% knock down of protein). TIMP4 protein was increased in placenta from women with sPE (3.5 ± 0.4 pg/µg, n = 8), compared with preterm (1.7 ± 0.17 pg/µg, n = 9) and term controls (1.6 ± 0.16 pg/µg, n = 9; P< 0.01; quantified by enzyme-linked immunosorbent assay and visualized using immunohistochemistry) with reduced GCM1 expression, mostly in the pathologic syncytial knots.
  
  
  CONCLUSIONS
  TIMP4 is a downstream target of GCM1 that may link the consequences of reduced GCM-1-directed trophoblast differentiation to histologic and functional components of disordered placentation in sPE.
authors.affiliation: Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON, Canada. drewlo@lunenfeld.ca
authors.forename: Sascha
authors.initials: S
authors.lastname: Drewlo
authors.forename: Marie
authors.initials: M
authors.lastname: Czikk
authors.forename: Dora
authors.initials: D
authors.lastname: Baczyk
authors.forename: Stephen
authors.initials: S
authors.lastname: Lye
authors.forename: John
authors.initials: J
authors.lastname: Kingdom
mesh_terms: D015153:Blotting, Western; D002460:Cell Line; D002824:Chorionic Villi / Q000378:metabolism*; D004268:DNA-Binding Proteins; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D011225:Pre-Eclampsia / Q000235:genetics / Q000378:metabolism*; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019714:Tissue Inhibitor of Metalloproteinases / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000502:physiology*; D000097792:Tissue Inhibitor of Metalloproteinase-4
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D019714:Tissue Inhibitor of Metalloproteinases; D014157:Transcription Factors; D000097792:Tissue Inhibitor of Metalloproteinase-4; C491089:GCM1 protein, human