title: ZO-1 is involved in trophoblastic cell differentiation in human placenta.
abstract: Trophoblastic cell-cell fusion is an essential event required during human placental development. Several membrane proteins have been described to be directly involved in this process, including connexin 43 (Cx43), syncytin 1 (Herv-W env), and syncytin 2 (Herv-FRD env glycoprotein). Recently, zona occludens (ZO) proteins (peripheral membrane proteins associated with tight junctions, adherens junctions, and gap junctions) were shown to be involved in mouse placental development. Moreover, zona occludens 1 (ZO-1) was localized mainly at the intercellular boundaries between human trophoblastic cells. Therefore the role of ZO-1 in the dynamic process of human trophoblastic cell-cell fusion was investigated using primary trophoblastic cells in culture. In vitro as in situ, ZO-1 was localized mainly at the intercellular boundaries between trophoblastic cells where its expression substantially decreased during differentiation and during fusion. At the same time, Cx43 was localized at the interface of trophoblastic cells and its expression increased during differentiation. To determine a functional role for ZO-1 during trophoblast differentiation, small interfering RNA (siRNA) was used to knock down ZO-1 expression. Cytotrophoblasts treated with ZO-1 siRNA fused poorly, but interestingly, decreased Cx43 expression without altering the functionality of trophoblastic cell-cell communication as measured by relative permeability time constant determined using gap-FRAP experiments. Because kinetics of Cx43 and ZO-1 proteins show a mirror image, a potential association of these two proteins was investigated. By using coimmunoprecipitation experiments, a physical interaction between ZO-1 and Cx43 was demonstrated. These results demonstrate that a decrease in ZO-1 expression reduces human trophoblast cell-cell fusion and differentiation.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U767, Paris, USA.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Pidoux
authors.forename: Pascale
authors.initials: P
authors.lastname: Gerbaud
authors.forename: Sédami
authors.initials: S
authors.lastname: Gnidehou
authors.forename: Michael
authors.initials: M
authors.lastname: Grynberg
authors.forename: Graziello
authors.initials: G
authors.lastname: Geneau
authors.forename: Jean
authors.initials: J
authors.lastname: Guibourdenche
authors.forename: Diane
authors.initials: D
authors.lastname: Carette
authors.forename: Laurent
authors.initials: L
authors.lastname: Cronier
authors.forename: Danièle
authors.initials: D
authors.lastname: Evain-Brion
authors.forename: André
authors.initials: A
authors.lastname: Malassiné
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Frendo
mesh_terms: D002454:Cell Differentiation; D002459:Cell Fusion; D048430:Cell Shape; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000378:metabolism; D018031:Connexin 43 / Q000378:metabolism; D051180:Desmoplakins / Q000378:metabolism; D005260:Female; D036681:Fluorescence Recovery After Photobleaching; D005865:Gestational Age; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D007365:Intercellular Junctions / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010920:Placenta / Q000166:cytology / Q000378:metabolism*; D011247:Pregnancy; D011485:Protein Binding; D034622:RNA Interference; D013997:Time Factors; D014327:Trophoblasts / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein
chemical_list: D006063:Chorionic Gonadotropin; D018031:Connexin 43; C495294:DSP protein, human; D051180:Desmoplakins; D008565:Membrane Proteins; D010750:Phosphoproteins; C569042:TJP1 protein, human; C569043:Tjp1 protein, mouse; D062826:Zonula Occludens-1 Protein