title: Human endogenous retrovirus-FRD envelope protein (syncytin 2) expression in normal and trisomy 21-affected placenta.
abstract: Human trophoblast expresses two fusogenic retroviral envelope proteins, the widely studied syncytin 1, encoded by HERV-W and the recently characterized syncytin 2 encoded by HERV-FRD. Here we studied syncytin 2 in normal and Trisomy 21-affected placenta associated with abnormal trophoblast differentiation. Syncytin 2 immunolocalization was restricted throughout normal pregnancy to some villous cytotrophoblastic cells (CT). During the second trimester of pregnancy, syncytin 2 was immunolocalized in some cuboidal CT in T21 placentas, whereas in normal placentas it was observed in flat CT, extending into their cytoplasmic processes. In vitro, CT isolated from normal placenta fuse and differentiate into syncytiotrophoblast. At the same time, syncytin 2 transcript levels decreased significantly with syncytiotrophoblast formation. In contrast, CT isolated from T21-affected placentas fused and differentiated poorly and no variation in syncytin 2 transcript levels was observed. Syncytin 2 expression illustrates the abnormal trophoblast differentiation observed in placenta of fetal T21-affected pregnancies.
authors.affiliation: INSERM, U767, 4 avenue de l'Observatoire 75006 Paris, France. andre.malassine@univ-paris5.fr
authors.forename: André
authors.initials: A
authors.lastname: Malassiné
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Frendo
authors.forename: Sandra
authors.initials: S
authors.lastname: Blaise
authors.forename: Karen
authors.initials: K
authors.lastname: Handschuh
authors.forename: Pascale
authors.initials: P
authors.lastname: Gerbaud
authors.forename: Vassilis
authors.initials: V
authors.lastname: Tsatsaris
authors.forename: Thierry
authors.initials: T
authors.lastname: Heidmann
authors.forename: Danièle
authors.initials: D
authors.lastname: Evain-Brion
mesh_terms: D002454:Cell Differentiation; D002478:Cells, Cultured; D004314:Down Syndrome / Q000378:metabolism*; D020077:Endogenous Retroviruses / Q000378:metabolism*; D005260:Female; D006801:Humans; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000378:metabolism*; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism
chemical_list: C518353:ERVFRD-1 protein, human; D011257:Pregnancy Proteins