title: β-1,4-Galactosyltransferase III suppresses extravillous trophoblast invasion through modifying β1-integrin glycosylation.
abstract: BACKGROUND
  Glycosylation controls diverse protein functions and regulates various cellular phenotypes. Trophoblast invasion is essential for normal placental development. However, the role of glycosylation in human placenta throughout pregnancy is still unclear. The β-1,4-galactosyltransferase III (B4GALT3) has been found to regulate cancer cell invasion. We therefore investigated the expression of B4GALT3 in placenta and its roles in trophoblast.
  
  
  METHODS
  B4GALT3 protein expression was examined by quantitative Western blotting analysis in human placentas. For identification of B4GALT3-positive cells in normal human placenta, immunohistochemistry and immunofluorescence methods were used. To investigate effects of B4GALT3 on extravillous trophoblast (EVT)-like cell and primary EVT cells, we analyzed cell growth, adhesion, migration, and invasion in mock and B4GALT3-transfected cell.
  
  
  RESULTS
  B4GALT3 expression significantly increased in third trimester human placenta. Immunostaining revealed that B4GALT3 expressed in placental villous cytotrophoblast, syncytiotrophoblast, and a subpopulation of EVT cells throughout pregnancy. Interestingly, we found increases in the expression level and percentage of B4GALT3-positive cells in third trimester EVT, but not in syncytiotrophoblasts and cytotrophoblasts of placental villi. Overexpression of B4GALT3 in HTR8/SVneo cells and primary trophoblast cells significantly suppressed cell migration. In addition, B4GALT3 suppressed cell invasion, and enhanced cell adhesion to laminin in HTR8/SVneo cells. Notably, we found that B4GALT3 modified glycans on β1-integrin, suppressed focal adhesion kinase (FAK) signaling, and enhanced β1-integrin degradation.
  
  
  CONCLUSIONS
  We propose that B4GALT3-mediated glycosylation change not only enhances β1-integrin binding to laminin, but also attenuates β1-integrin stability. Our findings suggest that B4GALT3 is a critical regulator for suppressing EVT invasion in the late stages of pregnancy.
authors: Department of Anatomy, Faculty of Medicine, Chung Shan Medical University, Taichung 402, Taiwan; Department of Pediatrics, Chung Shan Medical University Hospital, Taichung 402, Taiwan.
authors: W-C
authors: WC
authors: Liao
authors: Research and Development Center for Immunology, China Medical University, Taichung 404, Taiwan.
authors: C-H
authors: CH
authors: Liu
authors: Department of Neurosurgery, Chang-Gung Memorial Hospital, Taoyuan 333, Taiwan.
authors: C-H
authors: CH
authors: Chen
authors: Department of Surgery, National Taiwan University Hospitaland College of Medicine, National Taiwan University, Taipei 100, Taiwan.
authors: W-M
authors: WM
authors: Hsu
authors: Department of Obstetrics and Gynecology, National Taiwan University Hospital, Chung-Shan South Road, Taipei 100, Taiwan.
authors: Y-Y
authors: YY
authors: Liao
authors: Department of Anatomy, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors: H-M
authors: HM
authors: Chang
authors: Department of Anatomy, Faculty of Medicine, Chung Shan Medical University, Taichung 402, Taiwan.
authors: C-T
authors: CT
authors: Lan
authors: Graduate Institute of Anatomy and Cell Biology, National Taiwan University College of Medicine, Taipei 100, Taiwan.
authors: M-C
authors: MC
authors: Huang
authors: Department of Obstetrics and Gynecology, National Taiwan University Hospital, Chung-Shan South Road, Taipei 100, Taiwan. Electronic address: mchuang@ntu.edu.tw.
authors: M-K
authors: MK
authors: Shyu
mesh_terms: D000328:Adult; D002448:Cell Adhesion; D002460:Cell Line; D002465:Cell Movement; D002478:Cells, Cultured; D015536:Down-Regulation; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006031:Glycosylation; D006801:Humans; D007150:Immunohistochemistry; D019012:Integrin beta1 / Q000737:chemistry / Q000378:metabolism*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D009237:N-Acetyllactosamine Synthase / Q000235:genetics / Q000378:metabolism*; D010929:Placentation; D011247:Pregnancy; D011499:Protein Processing, Post-Translational; D055550:Protein Stability; D011994:Recombinant Proteins / Q000378:metabolism; D014327:Trophoblasts / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*
chemical_list: D019012:Integrin beta1; D007527:Isoenzymes; D011994:Recombinant Proteins; D009237:N-Acetyllactosamine Synthase
keywords: B4GALT3; Extraillous trophoblast; Glycosylation; Integrin; Invasion; Placenta