Alteration of the function of the UDP-glucuronosyltransferase 1A subfamily by cytochrome P450 3A4: Different susceptibility for UGT isoforms and UGT1A1/7 variantss

Yuji Ishii, Hiroki Koba, Kousuke Kinoshita, Toshiya Oizaki, Yuki Iwamoto, Shuso Takeda, Yuu Miyauchi, Yoshio Nishimura, Natsuki Egoshi, Futoshi Taura, Satoshi Morimoto, Shin'Ichi Ikushiro, Kiyoshi Nagata, Yasushi Yamazoe, Peter I. MacKenzie, Hideyuki Yamada

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Functional protein-protein interactions between UDPglucuronosyltransferase (UGT)1A isoforms and cytochrome P450 (CYP)3A4 were studied. To this end, UGT1A-catalyzed glucuronidation was assayed in Sf-9 cells that simultaneously expressed UGT and CYP3A4. In the kinetics of UGT1A6-catalyzed glucuronidation of serotonin, both Michaelis constant (Km) and maximal velocity (V max) were increased by CYP3A4. When CYP3A4 was coexpressed with either UGT1A1 or 1A7, the Vmax for the glucuronidation of the irinotecan metabolite (SN-38) was significantly increased. S50 and KKm both which are the substrate concentration giving 0.5 V max were little affected by simultaneous expression of CYP3A4. This study also examined the catalytic properties of the allelic variants of UGT1A1 and 1A7 and their effects on the interaction with CYP3A4. Although the UGT1A1- catalyzing activity of 4-methylumbelliferone glucuronidation was reduced in its variant, UGT1A1*6, the coexpression of CYP3A4 restored the impaired function to a level comparable with the wild type. Similarly, simultaneous expression of CYP3A4 increased the Vmax of UGT1A7*1 (wild type) and *2 (N129K and R131K), whereas the same was not observed in UGT1A7*3 (N129K, R131K, and W208R). In the kinetics involving different concentrations of UDPglucuronic acid (UDP-GlcUA), the KKm for UDP-GlcUA was significantly higher for UGT1A7*2 and *3 than *1. The KKm of UGT1A7*1 and *3 was increased by CYP3A4, whereas *2 did not exhibit any such change. These results suggest that (1) CYP3A4 changes the catalytic function of the UGT1A subfamily in a UGT isoformspecific manner and (2) nonsynonymous mutations in UGT1A7*3 reduce not only the ability of UGT to use UDP-GlcUA but also CYP3A4-mediated enhancement of catalytic activity, whereas CYP3A4 is able to restore the UGT1A1*6 function.

元の言語英語
ページ(範囲)229-238
ページ数10
ジャーナルDrug Metabolism and Disposition
42
発行部数2
DOI
出版物ステータス出版済み - 2 2014

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmaceutical Science

フィンガープリント Alteration of the function of the UDP-glucuronosyltransferase 1A subfamily by cytochrome P450 3A4: Different susceptibility for UGT isoforms and UGT1A1/7 variantss' の研究トピックを掘り下げます。これらはともに一意のフィンガープリントを構成します。

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    Ishii, Y., Koba, H., Kinoshita, K., Oizaki, T., Iwamoto, Y., Takeda, S., Miyauchi, Y., Nishimura, Y., Egoshi, N., Taura, F., Morimoto, S., Ikushiro, SI., Nagata, K., Yamazoe, Y., MacKenzie, P. I., & Yamada, H. (2014). Alteration of the function of the UDP-glucuronosyltransferase 1A subfamily by cytochrome P450 3A4: Different susceptibility for UGT isoforms and UGT1A1/7 variantss. Drug Metabolism and Disposition, 42(2), 229-238. https://doi.org/10.1124/dmd.113.054833