title: The Roles of Syncytin-Like Proteins in Ruminant Placentation.
abstract: Recent developments in genome sequencing techniques have led to the identification of huge numbers of endogenous retroviruses (ERV) in various mammals. ERVs, which occupy 8%-13% of mammalian genomes, are believed to affect mammalian evolution and biological diversity. Although the functional significance of most ERVs remains to be elucidated, several ERVs are thought to have pivotal roles in host physiology. We and other groups recently identified ERV envelope proteins (e.g., Fematrin-1, Syncytin-Rum1, endogenous Jaagsiekte sheep retrovirus Env) that may determine the morphogenesis of the unique fused trophoblast cells, termed trinucleate cells and syncytial plaques, found in ruminant placentas; however, there are still a number of outstanding issues with regard to the role of ERVs that remain to be resolved. Here, we review what is known about how these ERVs have contributed to the development of ruminant-specific trophoblast cells.
authors.affiliation: Department of Infectious Diseases, Kyoto Prefectural University of Medicine, 465 Kawaramachi-hirokoji-Kajiicho, Kamigyo-ku, Kyoto 602-8566, Japan. nakayayuki@gmail.com.|Laboratory of Signal Transduction, Department of Cell Biology, Institute for Virus Research, Kyoto University, 53 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507, Japan. nakayayuki@gmail.com.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Nakaya
authors.affiliation: Laboratory of Signal Transduction, Department of Cell Biology, Institute for Virus Research, Kyoto University, 53 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507, Japan. takavet@gmail.com.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Miyazawa
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D020077:Endogenous Retroviruses / Q000201:enzymology*; D005260:Female; D015686:Gene Products, env / Q000378:metabolism*; D010929:Placentation; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000378:metabolism*; D012418:Ruminants / Q000502:physiology* / Q000821:virology; D014327:Trophoblasts / Q000502:physiology
chemical_list: D015686:Gene Products, env; D011257:Pregnancy Proteins; C405335:syncytin
keywords: cell-to-cell fusion; endogenous retrovirus; envelope glycoprotein; fematrin-1; placenta; ruminants; syncytin-rum1