title: Functional characterization of two newly identified Human Endogenous Retrovirus coding envelope genes.
abstract: A recent in silico search for coding sequences of retroviral origin present in the human genome has unraveled two new envelope genes that add to the 16 genes previously identified. A systematic search among the latter for a fusogenic activity had led to the identification of two bona fide genes, named syncytin-1 and syncytin-2, most probably co-opted by primate genomes for a placental function related to the formation of the syncytiotrophoblast by cell-cell fusion. Here, we show that one of the newly identified envelope gene, named envP(b), is fusogenic in an ex vivo assay, but that its expression - as quantified by real-time RT-PCR on a large panel of human tissues - is ubiquitous, albeit with a rather low value in most tissues. Conversely, the second envelope gene, named envV, discloses a placenta-specific expression, but is not fusogenic in any of the cells tested. Altogether, these results suggest that at least one of these env genes may play a role in placentation, but most probably through a process different from that of the two previously identified syncytins.
authors.affiliation: Unité de Biologie des Rétrovirus, Département de Virologie, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris cedex 15, France. sblaise@pasteur.fr
authors.forename: Sandra
authors.initials: S
authors.lastname: Blaise
authors.forename: Nathalie
authors.initials: N
authors.lastname: de Parseval
authors.forename: Thierry
authors.initials: T
authors.lastname: Heidmann
mesh_terms: D000818:Animals; D001483:Base Sequence; D002415:Cats; D002459:Cell Fusion; D004285:Dogs; D020077:Endogenous Retroviruses / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015686:Gene Products, env / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015752:Genes, env; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D051379:Mice; D008969:Molecular Sequence Data; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D014327:Trophoblasts / Q000502:physiology
chemical_list: D015686:Gene Products, env; D011257:Pregnancy Proteins; C405335:syncytin