Layer II of placental syncytiotrophoblasts expresses MDR1 and BCRP at the apical membrane in rodents

• Published in: Reproductive toxicology (Elmsford, N.Y.) Vol. 65; pp. 375 - 381
• Main Authors: Akashi, Tomoya, Nishimura, Tomohiro, Takaki, Yoshiya, Takahashi, Masaya, Shin, Bo-Chul, Tomi, Masatoshi, Nakashima, Emi
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-10-2016
• Subjects: Animals; ATP Binding Cassette Transporter, Sub-Family G, Member 2 - genetics; ATP Binding Cassette Transporter, Sub-Family G, Member 2 - metabolism; ATP-Binding Cassette, Sub-Family B, Member 1 - genetics; ATP-Binding Cassette, Sub-Family B, Member 1 - metabolism; BCRP; Female; MDR1; Mice, Inbred C57BL; Mice, Knockout; Placenta - cytology; Placenta - metabolism; Placental barrier; Pregnancy; Rats, Sprague-Dawley; RNA, Messenger - metabolism; Rodent; Syncytiotrophoblast; Transporter; Trophoblasts - metabolism; BCRP; GLUT1; MDR1; Placental barrier; SynT-II; SynTI; Cx26; Syncytiotrophoblast; Rodent; Transporter
• ISSN: 0890-6238; 1873-1708
• DOI: 10.1016/j.reprotox.2016.09.002

•In rodents, MDR1 and BCRP are expressed in syncytiotrophoblast layer II.•In layer II, MDR1 and BCRP are localized in the apical membrane.•Layer II plays a defensive role in the machinery of the placental barrier.
The purpose of this study is to clarify the subcellular localizations of multidrug resistance protein 1 (MDR1)/ABCB1 and breast cancer resistance protein (BCRP)/ABCG2 in the rodent placental SynT bilayer, i.e., a maternal-facing (SynT-I) layer and a fetal-facing (SynT-II) layer. In double immunofluorescence staining, the signals of MDR1 and BCRP appeared midway between the signals of glucose transporter 1 on the apical membrane of SynT-I and the basal plasma membrane of SynT-II, and mostly overlapped with signals of connexin 26, which forms gap junctions between SynT-I and SynT-II. In detail, median intensities (pixels) of the MDR1 and BCRP signals were significantly closer to the fetal circulation as compared to the location of connexin 26 signals. In double in situ hybridization studies, the signals of Mdr1b mRNA mostly overlapped with those of Syncytin-B, a SynT-II marker. In conclusion, MDR1 and BCRP are expressed on apical membranes of the rodent placental SynT-II layer.