Role of OAT4 in Uptake of Estriol Precursor 16α-Hydroxydehydroepiandrosterone Sulfate Into Human Placental Syncytiotrophoblasts From Fetus.
Estriol biosynthesis in human placenta requires the uptake of a fetal liver-derived estriol precursor, 16α-hydroxydehydroepiandrosterone sulfate (16α-OH DHEAS), by placental syncytiotrophoblasts at their basal plasma membrane (BM), which faces the fetal circulation. The aim of this work is to identify the transporter(s) mediating 16α-OH DHEAS uptake at the fetal side of syncytiotrophoblasts by using human placental BM-enriched vesicles and to examine the contribution of the putative transporter to estriol synthesis at the cellular level, using choriocarcinoma JEG-3 cells. Organic anion transporter (OAT)-4 and organic anion transporting polypeptide 2B1 proteins were enriched in human placental BM vesicles compared with crude membrane fraction. Uptake of [(3)H]16α-OH DHEAS by BM vesicles was partially inhibited in the absence of sodium but was significantly increased in the absence of chloride and after preloading glutarate. Uptake of [(3)H]16α-OH DHEAS by BM vesicles was significantly inhibited by OAT4 substrates such as dehydroepiandrosterone sulfate, estrone-3-sulfate, and bromosulfophthalein but not by cyclosporin A, tetraethylammonium, p-aminohippuric acid, or cimetidine. These characteristics of vesicular [(3)H]16α-OH DHEAS uptake are in good agreement with those of human OAT4-transfected COS-7 cells as well as forskolin-differentiated JEG-3 cells. Estriol secretion from differentiated JEG-3 cells was detected when the cells were incubated with 16α-OH DHEAS for 8 hours but was inhibited in the presence of 50 μM bromosulfophthalein. Our results indicate that OAT4 at the BM of human placental syncytiotrophoblasts plays a predominant role in the uptake of 16α-OH DHEAS for placental estriol synthesis.
Faculty of Pharmacy (M.T., H.E., M.O., T.T., S.N., K.H., T.N., E.N.), Keio University, Minato-ku 105-8512, Tokyo, Japan; School of Pharmaceutical Sciences (K.H.), Teikyo University, Itabashi-ku 173-8605, Tokyo, Japan; and Department of Obstetrics and Gynecology (T.M.), School of Medicine, Keio University, Shinjuku-ku 160-8512, Tokyo, Japan.
Masatoshi
M
Tomi
Faculty of Pharmacy (M.T., H.E., M.O., T.T., S.N., K.H., T.N., E.N.), Keio University, Minato-ku 105-8512, Tokyo, Japan; School of Pharmaceutical Sciences (K.H.), Teikyo University, Itabashi-ku 173-8605, Tokyo, Japan; and Department of Obstetrics and Gynecology (T.M.), School of Medicine, Keio University, Shinjuku-ku 160-8512, Tokyo, Japan.
Hiromi
H
Eguchi
Faculty of Pharmacy (M.T., H.E., M.O., T.T., S.N., K.H., T.N., E.N.), Keio University, Minato-ku 105-8512, Tokyo, Japan; School of Pharmaceutical Sciences (K.H.), Teikyo University, Itabashi-ku 173-8605, Tokyo, Japan; and Department of Obstetrics and Gynecology (T.M.), School of Medicine, Keio University, Shinjuku-ku 160-8512, Tokyo, Japan.
Mayuko
M
Ozaki
Faculty of Pharmacy (M.T., H.E., M.O., T.T., S.N., K.H., T.N., E.N.), Keio University, Minato-ku 105-8512, Tokyo, Japan; School of Pharmaceutical Sciences (K.H.), Teikyo University, Itabashi-ku 173-8605, Tokyo, Japan; and Department of Obstetrics and Gynecology (T.M.), School of Medicine, Keio University, Shinjuku-ku 160-8512, Tokyo, Japan.
Tomohiro
T
Tawara
Faculty of Pharmacy (M.T., H.E., M.O., T.T., S.N., K.H., T.N., E.N.), Keio University, Minato-ku 105-8512, Tokyo, Japan; School of Pharmaceutical Sciences (K.H.), Teikyo University, Itabashi-ku 173-8605, Tokyo, Japan; and Department of Obstetrics and Gynecology (T.M.), School of Medicine, Keio University, Shinjuku-ku 160-8512, Tokyo, Japan.
Sachika
S
Nishimura
Faculty of Pharmacy (M.T., H.E., M.O., T.T., S.N., K.H., T.N., E.N.), Keio University, Minato-ku 105-8512, Tokyo, Japan; School of Pharmaceutical Sciences (K.H.), Teikyo University, Itabashi-ku 173-8605, Tokyo, Japan; and Department of Obstetrics and Gynecology (T.M.), School of Medicine, Keio University, Shinjuku-ku 160-8512, Tokyo, Japan.
Kei
K
Higuchi
Faculty of Pharmacy (M.T., H.E., M.O., T.T., S.N., K.H., T.N., E.N.), Keio University, Minato-ku 105-8512, Tokyo, Japan; School of Pharmaceutical Sciences (K.H.), Teikyo University, Itabashi-ku 173-8605, Tokyo, Japan; and Department of Obstetrics and Gynecology (T.M.), School of Medicine, Keio University, Shinjuku-ku 160-8512, Tokyo, Japan.
Tetsuo
T
Maruyama
Faculty of Pharmacy (M.T., H.E., M.O., T.T., S.N., K.H., T.N., E.N.), Keio University, Minato-ku 105-8512, Tokyo, Japan; School of Pharmaceutical Sciences (K.H.), Teikyo University, Itabashi-ku 173-8605, Tokyo, Japan; and Department of Obstetrics and Gynecology (T.M.), School of Medicine, Keio University, Shinjuku-ku 160-8512, Tokyo, Japan.
Tomohiro
T
Nishimura
Faculty of Pharmacy (M.T., H.E., M.O., T.T., S.N., K.H., T.N., E.N.), Keio University, Minato-ku 105-8512, Tokyo, Japan; School of Pharmaceutical Sciences (K.H.), Teikyo University, Itabashi-ku 173-8605, Tokyo, Japan; and Department of Obstetrics and Gynecology (T.M.), School of Medicine, Keio University, Shinjuku-ku 160-8512, Tokyo, Japan.
Emi
E
Nakashima
D000328:Adult; D000818:Animals; D019556:COS Cells; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D003687:Dehydroepiandrosterone / Q000031:analogs & derivatives* / Q000378:metabolism; D019314:Dehydroepiandrosterone Sulfate / Q000494:pharmacology; D004964:Estriol / Q000096:biosynthesis / Q000378:metabolism; D004970:Estrone / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D005333:Fetus; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D029362:Organic Anion Transporters, Sodium-Independent / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010920:Placenta / Q000187:drug effects / Q000378:metabolism; D011247:Pregnancy; D011868:Radioisotopes; D013448:Sulfobromophthalein / Q000494:pharmacology; D022161:Transport Vesicles / Q000378:metabolism; D014316:Tritium; D014327:Trophoblasts / Q000187:drug effects / Q000378:metabolism*
D029362:Organic Anion Transporters, Sodium-Independent; D011868:Radioisotopes; C427207:SLC22A11 protein, human; D013448:Sulfobromophthalein; D014316:Tritium; C024368:16-hydroxydehydroepiandrosterone sulfate; D004970:Estrone; D003687:Dehydroepiandrosterone; D019314:Dehydroepiandrosterone Sulfate; D004964:Estriol; C017296:estrone sulfate