Quantification of ENT1 and ENT2 Proteins at the Placental Barrier and Contribution of These Transporters to Ribavirin Uptake

Tomohiro Nishimura, Yuichiro Sano, Yu Takahashi, Saki Noguchi, Yasuo Uchida, Akinori Takagi, Takahiro Tanaka, Satomi Katakura, Emi Nakashima, Masanori Tachikawa, Tetsuo Maruyama, Tetsuya Terasaki, Masatoshi Tomi

Research output: Contribution to journalArticle

Abstract

The aims of this study are to quantify the protein levels of nucleoside transporters in placental microvillous membranes (MVMs) and to clarify the contributions of these transporters to ribavirin uptake at the placental barrier. Placental MVMs of human and rat expressed equilibrative nucleoside transporter (ENT) 1 protein, whereas the expression of ENT2 protein was obscure. Maternal-to-fetal transfer of [3H]ribavirin in rats was much higher than that of [14C]sucrose. The uptake of [3H]ribavirin by rat placental trophoblast TR-TBT 18 d-1 cells, which functionally express both ENT1 and ENT2 proteins, was saturable, and was significantly inhibited by 0.1 μM nitrobenzylthioinosine, which selectively abolishes ENT1-mediated uptake. Dipyridamole at 10 μM is capable of inhibiting ENT2 as well as ENT1, but a degree of inhibition by 10 μM dipyridamole on [3H]ribavirin uptake was not much different from that by 0.1 μM nitrobenzylthioinosine (ENT1-specific inhibitor). Therefore, ENT2 may contribute little to [3H]ribavirin uptake by these cells. Rat ENT1 cRNA-injected oocytes showed increased [3H]ribavirin uptake compared with water-injected oocytes, while rat ENT2 cRNA-injected oocytes did not. In conclusion, ENT1 protein expressed in placental MVMs appears to play a predominant role in the uptake of ribavirin.

Original languageEnglish
JournalJournal of Pharmaceutical Sciences
DOIs
Publication statusAccepted/In press - 2019 Jan 1

Fingerprint

Pregnancy Proteins
Ribavirin
Oocytes
Complementary RNA
Dipyridamole
Proteins
Membranes
Nucleoside Transport Proteins
Trophoblasts
Sucrose
Mothers
Water

Keywords

  • drug transport
  • membrane transporter(s)
  • nucleoside transporter
  • pharmacokinetics
  • placenta
  • pregnancy

ASJC Scopus subject areas

  • Pharmaceutical Science

Cite this

Quantification of ENT1 and ENT2 Proteins at the Placental Barrier and Contribution of These Transporters to Ribavirin Uptake. / Nishimura, Tomohiro; Sano, Yuichiro; Takahashi, Yu; Noguchi, Saki; Uchida, Yasuo; Takagi, Akinori; Tanaka, Takahiro; Katakura, Satomi; Nakashima, Emi; Tachikawa, Masanori; Maruyama, Tetsuo; Terasaki, Tetsuya; Tomi, Masatoshi.

In: Journal of Pharmaceutical Sciences, 01.01.2019.

Research output: Contribution to journalArticle

Nishimura, Tomohiro ; Sano, Yuichiro ; Takahashi, Yu ; Noguchi, Saki ; Uchida, Yasuo ; Takagi, Akinori ; Tanaka, Takahiro ; Katakura, Satomi ; Nakashima, Emi ; Tachikawa, Masanori ; Maruyama, Tetsuo ; Terasaki, Tetsuya ; Tomi, Masatoshi. / Quantification of ENT1 and ENT2 Proteins at the Placental Barrier and Contribution of These Transporters to Ribavirin Uptake. In: Journal of Pharmaceutical Sciences. 2019.
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abstract = "The aims of this study are to quantify the protein levels of nucleoside transporters in placental microvillous membranes (MVMs) and to clarify the contributions of these transporters to ribavirin uptake at the placental barrier. Placental MVMs of human and rat expressed equilibrative nucleoside transporter (ENT) 1 protein, whereas the expression of ENT2 protein was obscure. Maternal-to-fetal transfer of [3H]ribavirin in rats was much higher than that of [14C]sucrose. The uptake of [3H]ribavirin by rat placental trophoblast TR-TBT 18 d-1 cells, which functionally express both ENT1 and ENT2 proteins, was saturable, and was significantly inhibited by 0.1 μM nitrobenzylthioinosine, which selectively abolishes ENT1-mediated uptake. Dipyridamole at 10 μM is capable of inhibiting ENT2 as well as ENT1, but a degree of inhibition by 10 μM dipyridamole on [3H]ribavirin uptake was not much different from that by 0.1 μM nitrobenzylthioinosine (ENT1-specific inhibitor). Therefore, ENT2 may contribute little to [3H]ribavirin uptake by these cells. Rat ENT1 cRNA-injected oocytes showed increased [3H]ribavirin uptake compared with water-injected oocytes, while rat ENT2 cRNA-injected oocytes did not. In conclusion, ENT1 protein expressed in placental MVMs appears to play a predominant role in the uptake of ribavirin.",
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AU - Nishimura, Tomohiro

AU - Sano, Yuichiro

AU - Takahashi, Yu

AU - Noguchi, Saki

AU - Uchida, Yasuo

AU - Takagi, Akinori

AU - Tanaka, Takahiro

AU - Katakura, Satomi

AU - Nakashima, Emi

AU - Tachikawa, Masanori

AU - Maruyama, Tetsuo

AU - Terasaki, Tetsuya

AU - Tomi, Masatoshi

PY - 2019/1/1

Y1 - 2019/1/1

N2 - The aims of this study are to quantify the protein levels of nucleoside transporters in placental microvillous membranes (MVMs) and to clarify the contributions of these transporters to ribavirin uptake at the placental barrier. Placental MVMs of human and rat expressed equilibrative nucleoside transporter (ENT) 1 protein, whereas the expression of ENT2 protein was obscure. Maternal-to-fetal transfer of [3H]ribavirin in rats was much higher than that of [14C]sucrose. The uptake of [3H]ribavirin by rat placental trophoblast TR-TBT 18 d-1 cells, which functionally express both ENT1 and ENT2 proteins, was saturable, and was significantly inhibited by 0.1 μM nitrobenzylthioinosine, which selectively abolishes ENT1-mediated uptake. Dipyridamole at 10 μM is capable of inhibiting ENT2 as well as ENT1, but a degree of inhibition by 10 μM dipyridamole on [3H]ribavirin uptake was not much different from that by 0.1 μM nitrobenzylthioinosine (ENT1-specific inhibitor). Therefore, ENT2 may contribute little to [3H]ribavirin uptake by these cells. Rat ENT1 cRNA-injected oocytes showed increased [3H]ribavirin uptake compared with water-injected oocytes, while rat ENT2 cRNA-injected oocytes did not. In conclusion, ENT1 protein expressed in placental MVMs appears to play a predominant role in the uptake of ribavirin.

AB - The aims of this study are to quantify the protein levels of nucleoside transporters in placental microvillous membranes (MVMs) and to clarify the contributions of these transporters to ribavirin uptake at the placental barrier. Placental MVMs of human and rat expressed equilibrative nucleoside transporter (ENT) 1 protein, whereas the expression of ENT2 protein was obscure. Maternal-to-fetal transfer of [3H]ribavirin in rats was much higher than that of [14C]sucrose. The uptake of [3H]ribavirin by rat placental trophoblast TR-TBT 18 d-1 cells, which functionally express both ENT1 and ENT2 proteins, was saturable, and was significantly inhibited by 0.1 μM nitrobenzylthioinosine, which selectively abolishes ENT1-mediated uptake. Dipyridamole at 10 μM is capable of inhibiting ENT2 as well as ENT1, but a degree of inhibition by 10 μM dipyridamole on [3H]ribavirin uptake was not much different from that by 0.1 μM nitrobenzylthioinosine (ENT1-specific inhibitor). Therefore, ENT2 may contribute little to [3H]ribavirin uptake by these cells. Rat ENT1 cRNA-injected oocytes showed increased [3H]ribavirin uptake compared with water-injected oocytes, while rat ENT2 cRNA-injected oocytes did not. In conclusion, ENT1 protein expressed in placental MVMs appears to play a predominant role in the uptake of ribavirin.

KW - drug transport

KW - membrane transporter(s)

KW - nucleoside transporter

KW - pharmacokinetics

KW - placenta

KW - pregnancy

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