title: Syncytin 1 in the human placenta.
abstract: This study characterises HERV-W (syncytin 1) expression in normal and pathologic placenta and in BeWo cells. HERV-W mRNA levels were higher in the first trimester than at term, and similar patterns were observed with another retrovirally-derived mRNA species, ERV-3. N-glycosylated syncytin 1 precursor (73 kDa) is cleaved to surface-associated (SU) and transmembrane (TM) subunits. Both were evident in villous trophoblast, where perinuclear and punctate cytoplasmic deposits were observed, and linear TM subunit immunoreactivity was seen at the syncytial microvillous membrane. Punctate immunoreactivity was seen in BeWo cells with antibodies to SU and TM, and the two were co-localised. SU immunoreactivity was observed in association with fetal endothelium, and this effect was increased in tissue from pre-eclamptic placentas, which also showed a higher level of total SU protein. Absence of the TM subunit from endothelium suggests it is not a biosynthetic source. We suggest that SU is released from trophoblast into fetal circulation where it may bind vascular endothelium.
authors.affiliation: Division of Human Development, Maternal and Fetal Health Research Group, Manchester Academic Health Sciences Centre, Research Floor, St Mary's Hospital, Manchester M13 9WL, UK.
authors.forename: B S
authors.initials: BS
authors.lastname: Holder
authors.forename: C L
authors.initials: CL
authors.lastname: Tower
authors.forename: V M
authors.initials: VM
authors.lastname: Abrahams
authors.forename: J D
authors.initials: JD
authors.lastname: Aplin
mesh_terms: D045744:Cell Line, Tumor; D002822:Choriocarcinoma; D005260:Female; D005317:Fetal Growth Retardation / Q000378:metabolism; D015686:Gene Products, env / Q000235:genetics*; D006801:Humans; D010920:Placenta / Q000378:metabolism*; D011225:Pre-Eclampsia / Q000378:metabolism; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000235:genetics*; D011261:Pregnancy Trimester, First; D012333:RNA, Messenger / Q000378:metabolism; D014327:Trophoblasts / Q000378:metabolism
chemical_list: D015686:Gene Products, env; D011257:Pregnancy Proteins; D012333:RNA, Messenger; C405335:syncytin