Next Article in Journal
Chikungunya Virus–Vector Interactions
Next Article in Special Issue
In between: Gypsy in Drosophila melanogaster Reveals New Insights into Endogenous Retrovirus Evolution
Previous Article in Journal
HIV Eradication: Combinatorial Approaches to Activate Latent Viruses
Previous Article in Special Issue
Host Control of Insect Endogenous Retroviruses: Small RNA Silencing and Immune Response
Article Menu

Export Article

Open AccessReview
Viruses 2014, 6(11), 4609-4627; doi:10.3390/v6114609

Implication of Human Endogenous Retrovirus Envelope Proteins in Placental Functions

Département des Sciences Biologiques and Centre de recherche BioMed, Université du Québec à Montréal, 2080 Saint-Urbain, Montréal, PQ H2X 3X8, Canada
Author to whom correspondence should be addressed.
Received: 11 October 2014 / Revised: 2 November 2014 / Accepted: 7 November 2014 / Published: 24 November 2014
(This article belongs to the Special Issue Endogenous Viruses)
View Full-Text   |   Download PDF [651 KB, uploaded 12 May 2015]   |  


Human endogenous retroviruses (ERVs) represent 8% of the total human genome. Although the majority of these ancient proviral sequences have only retained non-coding long terminal repeats (LTRs), a number of “endogenized” retroviral genes encode functional proteins. Previous studies have underlined the implication of these ERV-derived proteins in the development and the function of the placenta. In this review, we summarize recent findings showing that two ERV genes, termed Syncytin-1 and Syncytin-2, which encode former envelope (Env) proteins, trigger fusion events between villous cytotrophoblasts and the peripheral multinucleated syncytiotrophoblast layer. Such fusion events maintain the stability of this latter cell structure, which plays an important role in fetal development by the active secretion of various soluble factors, gas exchange and regulation of fetomaternal immunotolerance. We also highlight new studies showing that these ERV proteins, in addition to their localization at the cell surface of cytotrophoblasts, are also incorporated on the surface of various extracellular microvesicles, including exosomes. Such exosome-associated proteins could be involved in the various functions attributed to these vesicles and could provide a form of tropism. Additionally, through their immunosuppressive domains, these ERV proteins could also contribute to fetomaternal immunotolerance in a local and more distal manner. These various aspects of the implication of Syncytin-1 and -2 in placental function are also addressed in the context of the placenta-related disorder, preeclampsia. View Full-Text
Keywords: human endogenous retrovirus; Syncytin-1 and -2; placenta; syncytiotrophoblast; immunotolerance; exosomes; pre-eclampsia human endogenous retrovirus; Syncytin-1 and -2; placenta; syncytiotrophoblast; immunotolerance; exosomes; pre-eclampsia

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Lokossou, A.G.; Toudic, C.; Barbeau, B. Implication of Human Endogenous Retrovirus Envelope Proteins in Placental Functions. Viruses 2014, 6, 4609-4627.

Show more citation formats Show less citations formats

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Viruses EISSN 1999-4915 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top