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The important biological roles of Syncytin-1 of human endogenous retrovirus W (HERV-W) and Syncytin-2 of HERV-FRD in the human placenta development

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Abstract

Background: Human endogenous retroviruses (HERVs) entered the germ line by retroviral infection from a distant ancestor over 30 million years ago and constitute 8% of the human genome. The majorities of HERVs are non-protein coding and lack function because of the accumulation of mutations, insertions, deletions, and/or truncations. However, a small number of HERV genes carried ORFs with beneficial functions for the host. Methods & results: In this review, we summarize the structural and important biological roles of two HERV gene products termed Syncytin-1 and Syncytin-2 in human placenta development. Indeed, two retroviral gene products that have important roles in mammalian development, Syncytin-1 (HERV-W) and Syncytin-2 (HERV-FRD), are prime examples encoded by env genes and expressed in the placental trophoblasts. Several pivotal studies revealed that Syncytins are fundamental genes implicated in regulating trophoblast fusion and placenta morphogenesis. Conclusion: Interestingly, it has been suggested that syncytins may also be implicated in non-fusogenic activities leading to apoptosis, proliferation, and immunosuppressive activities.

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Abbreviations

CTB :

Cytotrophoblast cells

EVTs :

Extravillous trophoblasts

Env :

Envelope

FcRn :

Neonatal Fc receptor

FP :

Fusion peptide

HERVs :

Human endogenous retroviruses

HLA :

Human leukocyte antigen

HEK293 :

Human embryonic kidney cells

HR :

Heptad repeat

hCG :

Human chorionic gonadotrophic

ISD :

Immunosuppressive domain

ICM :

Inner cell mass

PPT :

Polypurine tract

RBD :

Receptor binding domain

SU :

Surface

SP :

Signal peptide

SCT :

Syncytiotrophoblast

TM :

Transmembrane

TMD :

Transmembrane domain

TE :

Trophectoderm

6HB :

Six-helix bundle

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Correspondence to Somayeh Shatizadeh Malekshahi.

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Gholami barzoki , M., Shatizadeh Malekshahi, S., Heydarifard, Z. et al. The important biological roles of Syncytin-1 of human endogenous retrovirus W (HERV-W) and Syncytin-2 of HERV-FRD in the human placenta development. Mol Biol Rep 50, 7901–7907 (2023). https://doi.org/10.1007/s11033-023-08658-0

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