title: Expression analyses of human endogenous retroviruses (HERVs): tissue-specific and developmental stage-dependent expression of HERVs.
abstract: The evolutional and biological roles of human endogenous retroviruses (HERVs) are less recognized compared to those of L1. In the present study, we focused on the transcriptional activity of HERVs in normal human tissues and found five HERV loci that are actively expressed in normal tissues. All but one showed tissue specificity of expression: one was expressed in stomach and small intestine and three were in placenta. We subsequently examined by TaqMan-based RT-PCR assays the temporal expression profiles of the three placenta-specific HERVs along with syncytin and syncytin 2 and observed three patterns. Syncytin and HERV-Fb showed almost constant expression through gestations. Syncytin 2 gradually decreased as pregnancy proceeded. In contrast, expression from the HERV-H/F and HERV-K(HML-6) loci increased remarkably in term placentas. Term placentas in general showed larger interindividual differences in HERV expression levels. Our results suggest that HERVs might have more diverse effects than currently thought.
authors.affiliation: Department of Molecular Biology, Ryukyu University School of Medicine, 207 Uehara, Okinawa 903-0215, Japan.
authors.forename: Goichi
authors.initials: G
authors.lastname: Okahara
authors.forename: Shinobu
authors.initials: S
authors.lastname: Matsubara
authors.forename: Takaya
authors.initials: T
authors.lastname: Oda
authors.forename: Jun
authors.initials: J
authors.lastname: Sugimoto
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Jinno
authors.forename: Fuminori
authors.initials: F
authors.lastname: Kanaya
mesh_terms: D030541:Databases, Genetic; D020077:Endogenous Retroviruses / Q000235:genetics / Q000378:metabolism*; D020224:Expressed Sequence Tags; D005260:Female; D005333:Fetus / Q000821:virology*; D018507:Gene Expression Regulation, Developmental; D015686:Gene Products, env / Q000235:genetics / Q000378:metabolism; D006801:Humans; D017403:In Situ Hybridization; D009928:Organ Specificity / Q000235:genetics; D010920:Placenta / Q000821:virology; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014018:Tissue Distribution; D014158:Transcription, Genetic
chemical_list: D015686:Gene Products, env; D011257:Pregnancy Proteins; C405335:syncytin