Alzahrani Khalid J H, Ali Juma A M, Eze Anthonius A, Looi Wan Limm, Tagoe Daniel N A, Creek Darren J, Barrett Michael P, de Koning Harry P
Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom; Department of Clinical Laboratory, College of Applied Medical Sciences, Taif University, Taif, Saudi Arabia.
Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom; Al Jabal Al Gharbi University, Gharyan, Libya.
Int J Parasitol Drugs Drug Resist. 2017 Aug;7(2):206-226. doi: 10.1016/j.ijpddr.2017.04.003. Epub 2017 Apr 20.
Leishmania pyrimidine salvage is replete with opportunities for therapeutic intervention with enzyme inhibitors or antimetabolites. Their uptake into cells depends upon specific transporters; therefore it is essential to establish whether various Leishmania species possess similar pyrimidine transporters capable of drug uptake. Here, we report a comprehensive characterization of pyrimidine transport in L. major and L. mexicana. In both species, two transporters for uridine/adenosine were detected, one of which also transported uracil and the antimetabolites 5-fluoruracil (5-FU) and 5F,2'deoxyuridine (5F,2'dUrd), and was designated uridine-uracil transporter 1 (UUT1); the other transporter mediated uptake of adenosine, uridine, 5F,2'dUrd and thymidine and was designated Nucleoside Transporter 1 (NT1). To verify the reported L. donovani model of two NT1-like genes encoding uridine/adenosine transporters, and an NT2 gene encoding an inosine transporter, we cloned the corresponding L. major and L. mexicana genes, expressing each in T. brucei. Consistent with the L. donovani reports, the NT1-like genes of either species mediated the adenosine-sensitive uptake of [H]-uridine but not of [H]-inosine. Conversely, the NT2-like genes mediated uptake of [H]-inosine but not [H]-uridine. Among pyrimidine antimetabolites tested, 5-FU and 5F,2'dUrd were the most effective antileishmanials; resistance to both analogs was induced in L. major and L. mexicana. In each case it was found that the resistant cells had lost the transport capacity for the inducing drug. Metabolomics analysis found that the mechanism of action of 5-FU and 5F-2'dUrd was similar in both Leishmania species, with major changes in deoxynucleotide metabolism. We conclude that the pyrimidine salvage system is highly conserved in Leishmania species - essential information for the development of pyrimidine-based chemotherapy.
利什曼原虫嘧啶补救途径存在诸多利用酶抑制剂或抗代谢物进行治疗干预的机会。它们进入细胞依赖于特定的转运蛋白;因此,确定不同利什曼原虫物种是否拥有能够摄取药物的相似嘧啶转运蛋白至关重要。在此,我们报告了硕大利什曼原虫和墨西哥利什曼原虫中嘧啶转运的全面特征。在这两个物种中,检测到两种尿苷/腺苷转运蛋白,其中一种还转运尿嘧啶以及抗代谢物5-氟尿嘧啶(5-FU)和5-氟-2'-脱氧尿苷(5F,2'dUrd),并被命名为尿苷-尿嘧啶转运蛋白1(UUT1);另一种转运蛋白介导腺苷、尿苷、5F,2'dUrd和胸苷的摄取,被命名为核苷转运蛋白1(NT1)。为了验证已报道的杜氏利什曼原虫中两个编码尿苷/腺苷转运蛋白的类NT1基因和一个编码次黄苷转运蛋白的NT2基因的模型,我们克隆了相应的硕大利什曼原虫和墨西哥利什曼原虫基因,并在布氏锥虫中进行表达。与杜氏利什曼原虫的报道一致,任一物种的类NT1基因介导[³H]-尿苷的腺苷敏感性摄取,但不介导[³H]-次黄苷的摄取。相反,类NT2基因介导[³H]-次黄苷的摄取,但不介导[³H]-尿苷的摄取。在所测试的嘧啶抗代谢物中,5-FU和5F,2'dUrd是最有效的抗利什曼原虫药物;在硕大利什曼原虫和墨西哥利什曼原虫中均诱导出对这两种类似物的抗性。在每种情况下,发现抗性细胞丧失了对诱导药物的转运能力。代谢组学分析发现,5-FU和5F-2'dUrd在两种利什曼原虫中的作用机制相似,脱氧核苷酸代谢发生了重大变化。我们得出结论,嘧啶补救系统在利什曼原虫物种中高度保守——这是基于嘧啶的化疗发展的重要信息。