Implication of Human Endogenous Retrovirus Envelope Proteins in Placental Functions

Viruses

Adjimon Gatien Lokossou²  Caroline Toudic²  Benoit Barbeau¹ 

[1] Département des Sciences Biologiques and Centre de recherche BioMed, Université du Québec à Montréal, 2080 Saint-Urbain, Montréal, PQ H2X 3X8, Canada;

关键词: human endogenous retrovirus;    Syncytin-1 and -2;    placenta;    syncytiotrophoblast;    immunotolerance;    exosomes;    pre-eclampsia;   

DOI  :  10.3390/v6114609

来源: mdpi

【 摘 要 】

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.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.