Month: September 2022

MAMMALIAN ACQUISITIONS. "Here we describe the opposite situation, where a viral gene has been sequestered to serve an important function in the physiology of a mammalian host. This gene, encoding a protein that we have called syncytin, is the envelope gene of a recently identified human endogenous defective retrovirus, HERV-W2." https://lnkd.in/e9E9b8u View in LinkedIn

VIRAL GENE CAPTURE BY HOST. "The major sites of syncytin expression are placental syncytiotrophoblasts, multinucleated cells that originate from fetal trophoblasts." https://lnkd.in/e9E9b8u View in LinkedIn

ALIENS IN HUMAN DNA. "The host occasionally takes advantage of the presence of these ancestrally transmitted foreign genomes to serve physiological functions; several possible beneficial effects have been reported, including embryo implantation, gene variability, alternative splicing and polyadenylation, mother’s immunosuppression to protect the fetal allograft, protection against superinfection by exogenous retroviruses, and involvement in development and/or differentiation." https://lnkd.in/eZe8TGB View in LinkedIn

ERV BENEFITS. "Despite the fact that ERVs have been linked to various diseases, such as multiple sclerosis, cancer and diabetes, the retention of their genes during evolution suggests that they have provided a beneficial role to human survival. In this respect, studies that have highlighted a strong implication of ERV genes in the development and the function of the placenta represent the best example of their beneficial nature." https://lnkd.in/eNxap6v View in LinkedIn

HERVS BUILD PLACENTA. "One could postulate that HERV elements may have a beneficial role in human development. Since retroviral envelope proteins have fusogenic properties, it was assumed that HERV-encoded Env proteins may play a role in the formation of the syncytiotrophoblast layer of the placenta. The hypothesis that Env proteins are involved in syncytiotrophoblast formation has been recently confirmed." http://jvi.asm.org/content/79/1/341.full View in LinkedIn

BUDDING PARTICLES. "Electron micrographs of placental tissue from humans and a variety of other animals showed retrovirus-like particles budding from placental cells, particularly within the syncytiotrophoblast layer — the layer consisting of fused cells." https://lnkd.in/e6q2jTP View in LinkedIn

KEY VIRAL GENE. "Who would have thought that a virus could have anything to do with a tissue as important to life, and its development, as the placenta? A viral protein, now known as syncytin, whose gene was probably integrated into the primate genome over 25 millions years ago, is hugely expressed in placental tissue - especially at the beginning of embryonic development - and is giving signs of bearing an essential role in placental architecture." https://lnkd.in/eRQwBvJ View in LinkedIn

HOW CAN IT BE? "Could it be that placental evolution - and indeed mammalian evolution - finds its origins in the doings of a virus?" https://lnkd.in/eRQwBvJ View in LinkedIn

SELF/NON-SELF. "Another postulated beneficial role of HERV-encoded Env proteins is their involvement in suppressing possible maternal immunological reactions against the fetus based on the immunosuppressive activity characteristic of retroviral Env proteins." http://jvi.asm.org/content/79/1/341.full View in LinkedIn

ANTI-VIRAL. "Expressed HERVs may block infectious retroviruses, thus protecting the growing fetus from exogenous retroviruses that could possibly be transferred from the maternal blood." https://lnkd.in/bNEJmbG View in LinkedIn