title: Activin A Increases Human Trophoblast Invasion by Inducing SNAIL-Mediated MMP2 Up-Regulation Through ALK4.
abstract: BACKGROUND
  Activin A increases matrix metalloproteinase (MMP) 2 expression and cell invasion in human trophoblasts, but whether the expression of MMP2 is essential for the proinvasive effect of activin A has yet to be determined. Moreover, the identity of the activin receptor-like kinase (ALK; TGF-β type I receptors) and downstream transcription factors (eg, SNAIL and SLUG) mediating the effects of activin on MMP2 expression and trophoblast cell invasion remains unknown.
  
  
  OBJECTIVE
  To elucidate the role of MMP2 in activin A-induced human trophoblast cell invasion as well as the involvement of ALK4 and SNAIL.
  
  
  METHODS
  HTR8/SVneo immortalized human extravillous cytotrophoblast (EVT) cells and primary cultures of human first-trimester EVT cells were used as study models. Small interfering RNA (siRNA)-mediated knockdown approaches were used to investigate the molecular determinants of activin A-mediated functions.
  
  
  METHODS
  Levels of mRNA and protein were examined by reverse transcription-quantitative real-time PCR and Western blot, respectively. Cell invasiveness was measured by Matrigel-coated transwell assays.
  
  
  RESULTS
  Treatment of HTR8/SVneo cells with activin A increased the production of SNAIL, SLUG, and MMP2 without altering that of MMP9, TIMP1, TIMP2, TWIST, RUNX2, ZEB1, or ZEB2. Similarly, activin A up-regulated the mRNA and protein levels of SNAIL and MMP2 in primary EVT cells. Knockdown of SNAIL attenuated activin A-induced MMP2 up-regulation in HTR8/SVneo and primary EVT cells. In HTR8/SVneo cells, activin A-induced production of SNAIL and MMP2 was abolished by pretreatment with the TGF-β type I receptor (ALK4/5/7) inhibitor SB431542 or siRNA targeting ALK4, SMAD2/3, or common SMAD4. Likewise, knockdown of ALK4 or SMAD4 abolished the stimulatory effects of activin A on SNAIL and MMP2 expression in primary EVT cells. Importantly, activin A-induced HTR8/SVneo and primary EVT cell invasion were attenuated by siRNA-mediated depletion of ALK4 or MMP2.
  
  
  CONCLUSIONS
  Activin A induces human trophoblast cell invasion by inducing SNAIL-mediated MMP2 expression through ALK4 in a SMAD2/3-SMAD4-dependent manner.
authors: Department of Obstetrics and Gynaecology, Child & Family Research Institute, University of British Columbia, Vancouver, BC V5Z 4H4, Canada.
authors: Yan
authors: Y
authors: Li
authors: Department of Obstetrics and Gynaecology, Child & Family Research Institute, University of British Columbia, Vancouver, BC V5Z 4H4, Canada.
authors: Christian
authors: C
authors: Klausen
authors: Department of Obstetrics and Gynaecology, Child & Family Research Institute, University of British Columbia, Vancouver, BC V5Z 4H4, Canada.
authors: Hua
authors: H
authors: Zhu
authors: Department of Obstetrics and Gynaecology, Child & Family Research Institute, University of British Columbia, Vancouver, BC V5Z 4H4, Canada.
authors: Peter C K
authors: PC
authors: Leung
mesh_terms: D030201:Activin Receptors, Type I / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D028341:Activins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000328:Adult; D002461:Cell Line, Transformed; D002465:Cell Movement; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010929:Placentation; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D051785:Smad Proteins / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D012333:RNA, Messenger; C000604407:SNAI1 protein, human; D051785:Smad Proteins; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; C422405:activin A; D028341:Activins; C498932:ACVR1B protein, human; D030201:Activin Receptors, Type I; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2