ERVFRD1

ERVFRD1 is a human gene that encodes the envelope glycoprotein known as Syncytin-2, derived from an endogenous retrovirus of the FRD family. It is part of the human endogenous retrovirus (HERV) sequences integrated into the genome millions of years ago and later repurposed for a role in placental development.

Expression and localization: ERVFRD1 transcripts and Syncytin-2 are primarily expressed in the placenta, particularly in the trophoblast lineage that gives rise to the syncytiotrophoblast, a multinucleated layer essential for nutrient exchange between mother and fetus.

Function: The Syncytin-2 envelope protein is fusogenic and promotes cell-cell fusion, contributing to the formation of the syncytiotrophoblast layer during placental morphogenesis. This fusogenic activity is believed to involve interaction with its receptor, MFSD2A, on target cells, enabling membrane fusion events at the placental interface.

Evolution and regulation: ERVFRD1 exemplifies exaptation, where a viral gene has been retained and adapted to serve a host developmental function. Its placental expression is tightly regulated by placental transcription factors and epigenetic mechanisms, reflecting its specialized role in pregnancy.

Clinical relevance: Alterations in ERVFRD1/Synchytin-2 expression or function have been explored in the context of placental disorders and adverse pregnancy outcomes. Ongoing research aims to clarify the gene’s contribution to placental biology and disease.

See also: Syncytin-2; HERV-FRD; MFSD2A.