title: Characterization of the expression of the retinoid-related, testis-associated receptor (RTR) in trophoblasts.
abstract: Previous studies have provided evidence indicating that the nuclear orphan receptor RTR plays an important role during embryonic development and in spermatogenesis. In this study, we examine the expression of RTR in murine placenta and several human placental choriocarcinoma cell lines. Northern blot analysis showed high expression of RTR mRNA in placental tissue. In contrast to murine testis, which contains 7.4 and 2.3 kb transcripts, placental tissue expressed only the larger transcript. Examination of RTR expression in murine placental tissue by immunohistochemistry demonstrated the presence of RTR protein in the nuclei of giant trophoblasts and spongiotrophoblasts. RTR mRNA was also expressed in rat choriocarcinoma Rcho-1 cells and in the human placental choriocarcinoma cell lines BeWo, JAR, and JEG-3. In trophoblasts, RTR was co-expressed with the estrogen-related receptors ERR alpha and ERR beta. Giant trophoblast differentiation in Rcho-1 cells, characterized by induction of placental lactogen I (PL-I), was accompanied by a steady decrease in the expression of RTR mRNA and down-regulation of ERR beta expression while levels of ERR alpha mRNA did not change significantly. RTR was able to inhibit ERR alpha-mediated transactivation through the consensus RTR-response element (RTRE) likely by competing with ERR alpha for binding to the RTRE. These results suggest the possibility of cross-talk between RTR and ERR alpha receptor signalling pathways in trophoblasts.
authors.affiliation: Cell Biology Section, Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
authors.forename: D V
authors.initials: DV
authors.lastname: Mehta
authors.forename: Y-S
authors.initials: YS
authors.lastname: Kim
authors.forename: D
authors.initials: D
authors.lastname: Dixon
authors.forename: A M
authors.initials: AM
authors.lastname: Jetten
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002822:Choriocarcinoma / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D057136:Nuclear Receptor Subfamily 6, Group A, Member 1; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020239:Receptor Cross-Talk; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000235:genetics* / Q000378:metabolism*; D013737:Testis / Q000378:metabolism; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism*; D014594:Uterine Neoplasms / Q000235:genetics / Q000378:metabolism; D000097983:ERRalpha Estrogen-Related Receptor
chemical_list: D004268:DNA-Binding Proteins; D057136:Nuclear Receptor Subfamily 6, Group A, Member 1; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D011960:Receptors, Estrogen; D018168:Receptors, Retinoic Acid; D000097983:ERRalpha Estrogen-Related Receptor; C539950:NR6A1 protein, human; C539954:Nr6a1 protein, mouse; C539956:Nr6a1 protein, rat; C107914:estrogen receptor-related receptor beta