title: High Expression of Endogenous Retroviral Envelope Gene in the Equine Fetal Part of the Placenta.
abstract: Endogenous retroviruses (ERVs) are proviral phases of exogenous retroviruses that have co-evolved with vertebrate genomes for millions of years. Previous studies have identified the envelope (env) protein genes of retroviral origin preferentially expressed in the placenta which suggests a role in placentation based on their membrane fusogenic capacity and therefore they have been named syncytins. Until now, all the characterized syncytins have been associated with three invasive placentation types: the endotheliochorial (Carnivora), the synepitheliochorial (Ruminantia), and the hemochorial placentation (human, mouse) where they play a role in the syncytiotrophoblast formation. The purpose of the present study was to evaluate whether EqERV env RNA is expressed in horse tissues as well and investigate if the horse, possessing an epitheliochorial placenta, has "captured" a common retroviral env gene with syncytin-like properties in placental tissues. Interestingly, although in the equine placenta there is no syncytiotrophoblast layer at the maternal-fetal interface, our results showed that EqERV env RNA is highly expressed at that level, as expected for a candidate syncytin-like gene but with reduced abundance in the other somatic tissues (nearly 30-fold lower) thus suggesting a possible role in the placental tissue. Although the horse is one of the few domestic animals with a sequenced genome, few studies have been conducted about the EqERV and their expression in placental tissue has never been investigated.
authors.affiliation: Department of Veterinary Medicine, University of Perugia, Perugia, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Stefanetti
authors.affiliation: Department of Veterinary Medicine, University of Perugia, Perugia, Italy.
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Marenzoni
authors.affiliation: Department of Veterinary Medicine, University of Perugia, Perugia, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Passamonti
authors.affiliation: Department of Veterinary Medicine, University of Perugia, Perugia, Italy.
authors.forename: Katia
authors.initials: K
authors.lastname: Cappelli
authors.affiliation: Department of Genetics, Physical Anthropology and Animal Physiology, University of Basque Country-UPV/EHU, BioCruces Health Research Institute, Leioa, Spain.
authors.forename: Koldo
authors.initials: K
authors.lastname: Garcia-Etxebarria
authors.affiliation: Department of Veterinary Medicine, University of Perugia, Perugia, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Coletti
authors.affiliation: Department of Veterinary Medicine, University of Perugia, Perugia, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Capomaccio
mesh_terms: D000818:Animals; D020077:Endogenous Retroviruses / Q000235:genetics*; D005260:Female; D005333:Fetus / Q000821:virology*; D015967:Gene Expression Regulation, Viral; D015752:Genes, env; D006736:Horses / Q000821:virology*; D010920:Placenta / Q000821:virology*; D011247:Pregnancy; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D014759:Viral Envelope Proteins / Q000235:genetics*
chemical_list: D012367:RNA, Viral; D014759:Viral Envelope Proteins