Mutual role of ecto-5'-nucleotidase/CD73 and concentrative nucleoside transporter 3 in the intestinal uptake of dAMP
Mutual role of ecto-5'-nucleotidase/CD73 and concentrative nucleoside transporter 3 in the intestinal uptake of dAMP
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DOI：
10.1371/journal.pone.0223892
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发表时间：
2019-10-21
期刊：
影响因子：
3.7
通讯作者：
Iseki, Ken
中科院分区：
文献类型：
--
作者：
Narumi, Katsuya;Ohata, Tsukika;Iseki, Ken
2'-脱氧腺苷5'-单磷酸（dAMP）是DNA中发现的一种脱氧核糖核苷酸，影响肠细胞的生长。与食物一起摄入的外源DNA的胃肠道吸收的分子机制几乎没有研究。本研究的目的是探讨肠道吸收湿的机制。Caco-2细胞对[H-3]dAMP的摄取依赖于Na+-和ph，并受到各种核苷的抑制。相比之下，硝基苄基硫代肌苷（nitrobenzylthiioinosine， NMBPR）作为一种平衡核苷转运蛋白抑制剂，对[H-3]dAMP的摄取几乎没有抑制作用。此外，在COS-7细胞中短暂表达的人类浓缩核苷转运蛋白（CNT） 3介导了[3H]dAMP的摄取。动力学研究表明，cnt3介导的dAMP （59.6 μ M）摄取的K-m值与2'-脱氧腺苷（dAdo） （56.3 μ M）接近，而dAMP V-max （15.6 μ M）的K-m值与cnt3的K-m值相近。mg蛋白（-1）min（-1）比dAdo V-max （7782 pmol）少500倍。mg protein-1min-1)。此外，与单独表达CNT3的细胞相比，表达外5′-核苷酸酶/CD73的COS-7细胞对[3H]湿气的摄取更大。这些数据表明，尽管dAMP是CNT3的底物，但它被CD73去磷酸化为dAdo，并被肠腔有效地吸收为dAdo。
2'-Deoxyadenosine 5'-monophosphate (dAMP), a deoxyribonucleotide found in DNA, affects intestinal cell growth. The molecular mechanisms underlying gastrointestinal absorption of foreign DNA ingested along with food has hardly been investigated. The aim of this study was to investigate the mechanism underlying intestinal absorption of dAMP. The uptake of [H-3]dAMP by Caco-2 cells was Na+- and pH-dependent and was inhibited by various nucleosides. In contrast, nitrobenzylthioinosine (NMBPR), an equilibrative nucleoside transporter inhibitor, showed little inhibitory effects on [H-3]dAMP uptake. Additionally, human concentrative nucleoside transporter (CNT) 3, transiently expressed in COS-7 cells, mediated the uptake of [3H]dAMP. A kinetic study revealed that the K-m value of CNT3-mediated uptake of dAMP (59.6 mu M) was close to that of 2'-deoxyadenosine (dAdo) (56.3 mu M), whereas the dAMP V-max (15.6 pmol.mg protein(-1)min(-1)) was 500-fold lesser than the dAdo V-max (7782 pmol.mg protein-1min-1). Further, [3H]dAMP uptake was greater in COS-7 cells expressing ecto-5'-nucleotidase/CD73 with CNT3 than in those expressing CNT3 alone. These data suggest that, although dAMP is a substrate of CNT3, it is dephosphorylated to dAdo by CD73 and is efficiently absorbed as dAdo from the intestinal lumen.