title: Identification of CD147 (basigin) as a mediator of trophoblast functions.
abstract: OBJECTIVE
  Does CD147 regulate trophoblast functions in vitro?
  
  
  CONCLUSIONS
  CD147 exists as a receptor complex on human trophoblast and regulates the implantation, invasion and differentiation of trophoblast.
  
  
  BACKGROUND
  CD147 is a membrane protein implicated in a variety of physiological and pathological conditions due to its regulation of cell-cell recognition, cell differentiation and tissue remodeling. Reduced placental CD147 expression is associated with pre-eclampsia, but the mechanism of actions remains unclear.
  
  
  METHODS
  A loss of function approach or functional blocking antibody was used to study the function of CD147 in primary human cytotrophoblasts isolated from first trimester termination of pregnancy and/or in the BeWo cell line, which possesses characteristics of human cytotrophoblasts.
  
  
  METHODS
  CD147 expression was analyzed by immunofluorescence staining and western blotting. CD147-associated protein complex on plasma membrane were separated by blue native gel electrophoresis and identified by reversed-phase liquid chromatography coupled with quadrupole time-of-flight hybrid mass spectrometer. Cell proliferation and invasion were determined by fluorometric cell proliferation assays and transwell invasion assays, respectively. Matrix metalloproteinases (MMPs) and urokinase plasminogen activator (uPA) activities were measured by gelatin gel zymography and uPA assay kits, respectively. Cell migration was determined by wound-healing assays. Cell fusion was analyzed by immunocytochemistry staining of E-cadherin and 4',6-diamidino-2-phenylindole. The transcripts of matrix proteinases and trophoblast lineage markers were measured by quantitative PCR. Extracellular signal-regulated kinase (ERK) activation was analyzed by western blot using antibodies against ERKs.
  
  
  RESULTS
  CD147 exists as protein complexes on the plasma membrane of primary human cytotrophoblasts and BeWo cells. Several known CD147-interacting partners, including integrin β1 and monocarboxylate transporter-1, were identified. Suppression of CD147 by siRNA significantly (P < 0.05) reduced trophoblast-endometrial cell interaction, cell invasion, syncytialization, differentiation and ERK activation of BeWo cells. Consistently, anti-CD147 functional blocking antibody suppressed the invasiveness of primary human cytotrophoblasts. The reduced invasiveness was probably due to the restrained (P < 0.05) enzyme activities of MMP-2, MMP-9 and uPA.
  
  
  CONCLUSIONS
  Most of the above findings are based on BeWo cell lines. These results need to be confirmed with human first trimester primary cytotrophoblast.
  
  
  CONCLUSIONS
  This is the first study on the role of CD147 in trophoblast function. Further investigation on the function of CD147 and its associated protein complexes will enhance our understanding on human placentation.
  
  
  BACKGROUND
  This work was supported in part by the University of Hong Kong Grant 201011159200. The authors have no competing interests to declare.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Cheuk-Lun
authors.initials: CL
authors.lastname: Lee
authors.forename: Maggie P Y
authors.initials: MP
authors.lastname: Lam
authors.forename: Kevin K W
authors.initials: KK
authors.lastname: Lam
authors.forename: Carmen O N
authors.initials: CO
authors.lastname: Leung
authors.forename: Ronald T K
authors.initials: RT
authors.lastname: Pang
authors.forename: Ivan K
authors.initials: IK
authors.lastname: Chu
authors.forename: Tiffany H L
authors.initials: TH
authors.lastname: Wan
authors.forename: Joyce
authors.initials: J
authors.lastname: Chai
authors.forename: William S B
authors.initials: WS
authors.lastname: Yeung
authors.forename: Philip C N
authors.initials: PC
authors.lastname: Chiu
mesh_terms: D051926:Basigin / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015153:Blotting, Western; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D049109:Cell Proliferation; D002853:Chromatography, Liquid; D010064:Embryo Implantation / Q000502:physiology; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D020935:MAP Kinase Signaling System; D013058:Mass Spectrometry; D010920:Placenta / Q000166:cytology / Q000378:metabolism; D011247:Pregnancy; D034622:RNA Interference; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism / Q000502:physiology*
chemical_list: C497886:BSG protein, human; D051926:Basigin
keywords: CD147; basigin; implantation; invasion; trophoblast