Laboratory of Clinical Pharmaceutics & Therapeutics, Division of Pharma Sciences, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido, Japan.
Laboratory of Clinical Pharmaceutics & Therapeutics, Division of Pharma Sciences, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido, Japan.
Biochem Biophys Res Commun. 2021 Jun 18;558:120-125. doi: 10.1016/j.bbrc.2021.04.075. Epub 2021 Apr 25.
Human concentrative nucleoside transporters (CNTs) are responsible for cellular uptake of ribonucleosides; however, although it is important to better characterize CNT-subtype specificity to understand the systemic disposition of deoxyribonucleosides (dNs) and their analogs, the involvement of CNTs in transporting dNs is not fully understood. In this study, using COS-7 cells that transiently expressed CNT1, CNT2, or CNT3, we investigated if CNTs could transport not only ribonucleosides but also dNs, i.e., 2'-deoxyadenosine (dAdo), 2'-deoxyguanosine (dGuo), and 2'-deoxycytidine (dCyd). The cellular uptake study demonstrated that dAdo and dGuo were taken up by CNT2 but not by CNT1. Although dCyd was taken up by CNT1, no significant uptake was detected in COS-7 cells expressing CNT2. Similarly, these dNs were transported by CNT3. The apparent K values of their uptake were as follows: CNT1, K ＝ 141 μM for dCyd; CNT2, K ＝ 62.4 μM and 54.9 μM for dAdo and dGuo, respectively; CNT3, K ＝ 14.7 μM and 34.4 μM for dGuo and dCyd, respectively. These results demonstrate that CNTs contribute not only to ribonucleoside transport but also to the transport of dNs. Moreover, our data indicated that CNT1 and CNT2 selectively transported pyrimidine and purine dNs, respectively, and CNT3 was shown to transport both pyrimidine and purine dNs.
人类集中核苷转运体（CNTs）负责细胞摄取核苷；然而，尽管更好地描述 CNT 亚型特异性对于理解脱氧核苷（dNs）及其类似物的全身分布很重要，但 CNT 参与转运 dNs 的情况尚未完全了解。在这项研究中，我们使用瞬时表达 CNT1、CNT2 或 CNT3 的 COS-7 细胞，研究了 CNT 是否不仅可以转运核糖核苷，还可以转运 dNs，即 2'-脱氧腺苷（dAdo）、2'-脱氧鸟苷（dGuo）和 2'-脱氧胞苷（dCyd）。细胞摄取研究表明，dAdo 和 dGuo 被 CNT2 摄取，但不被 CNT1 摄取。虽然 dCyd 被 CNT1 摄取，但在表达 CNT2 的 COS-7 细胞中未检测到明显的摄取。同样，这些 dNs 也被 CNT3 转运。它们摄取的表观 K 值如下：CNT1，dCyd 的 K ＝ 141 μM；CNT2，dAdo 和 dGuo 的 K 分别为 62.4 μM 和 54.9 μM；CNT3，dGuo 和 dCyd 的 K 分别为 14.7 μM 和 34.4 μM。这些结果表明，CNTs 不仅有助于核糖核苷的转运，也有助于 dNs 的转运。此外，我们的数据表明，CNT1 和 CNT2 分别选择性地转运嘧啶和嘌呤 dNs，而 CNT3 则显示出转运嘧啶和嘌呤 dNs 的能力。
