Caroline Toudic: Département des Sciences Biologiques and Centre d'excellence en Recherche sur les Maladies Orphelines-Fondation Courtois, Université du Québec à Montréal, Montréal, QC H3C 3P8, Canada.
Maike Maurer: Robert-Koch Institute, 13353 Berlin, Germany.
Guillaume St-Pierre: Glycobiology and Bioimaging Laboratory, Research Centre for Infectious Diseases and Axe Maladies Infectieuses et Immunitaires, Laval University, Quebec City, QC G1V 0A6, Canada.
Yong Xiao: Département des Sciences Biologiques and Centre d'excellence en Recherche sur les Maladies Orphelines-Fondation Courtois, Université du Québec à Montréal, Montréal, QC H3C 3P8, Canada.
Norbert Bannert: Robert-Koch Institute, 13353 Berlin, Germany.
Julie Lafond: Département des Sciences Biologiques and Centre d'excellence en Recherche sur les Maladies Orphelines-Fondation Courtois, Université du Québec à Montréal, Montréal, QC H3C 3P8, Canada.
Éric Rassart: Département des Sciences Biologiques and Centre d'excellence en Recherche sur les Maladies Orphelines-Fondation Courtois, Université du Québec à Montréal, Montréal, QC H3C 3P8, Canada.
Sachiko Sato: Glycobiology and Bioimaging Laboratory, Research Centre for Infectious Diseases and Axe Maladies Infectieuses et Immunitaires, Laval University, Quebec City, QC G1V 0A6, Canada.
Benoit Barbeau: Département des Sciences Biologiques and Centre d'excellence en Recherche sur les Maladies Orphelines-Fondation Courtois, Université du Québec à Montréal, Montréal, QC H3C 3P8, Canada. ORCID
Syncytin-1 and -2 are glycoproteins encoded by human endogenous retrovirus (hERV) that, through their fusogenic properties, are needed for the formation of the placental syncytiotrophoblast. Previous studies suggested that these proteins, in addition to the EnvP(b) envelope protein, are also involved in other cell fusion events. Since galectin-1 is a β-galactoside-binding protein associated with cytotrophoblast fusion during placental development, we previously tested its effect on Syncytin-mediated cell fusion and showed that this protein differently modulates the fusogenic potential of Syncytin-1 and -2. Herein, we were interested in comparing the impact of galectin-1 on hERV envelope proteins in different cellular contexts. Using a syncytium assay, we first demonstrated that galectin-1 increased the fusion of Syncytin-2- and EnvP(b)-expressing cells. We then tested the infectivity of Syncytin-1 and -2 vs. VSV-G-pseudotyped viruses toward Cos-7 and various human cell lines. In the presence of galectin-1, infection of Syncytin-2-pseudotyped viruses augmented for all cell lines. In contrast, the impact of galectin-1 on the infectivity of Syncytin-1-pseudotyped viruses varied, being cell- and dose-dependent. In this study, we report the functional associations between three hERV envelope proteins and galectin-1, which should provide information on the fusogenic activity of these proteins in the placenta and other biological and pathological processes.
