The evolution of PfCRT from a carrier with a natural function to a drug transporting system in Plasmodium falciparum

在控制疟疾方面，耐药性仍然是一个悬而未决的问题。特别令人关切的是，人类疟疾寄生虫恶性疟原虫对喹诺酮类抗疟药物的反应性降低。喹啉衍生物用于疟疾化疗已有一个多世纪的历史。它们仍然是不可或缺的，作为青蒿素衍生物的伙伴药物，青蒿素衍生物作为青蒿素联合疗法构成了目前疟疾化疗的支柱。pfcrt基因编码药物/代谢物载体系统，该基因经常导致对喹啉类药物的反应变化，但也对大量结构无关的生物活性化合物产生反应。该项目的目的是：1)确定PfCRT的天然底物；ii)研究PfCRT如何从代谢物载体演变为药物运输系统；iii)开发工具来预测PfCRT在未来面对新药挑战时如何突变；iv)探讨PfCRT能否获得多药耐药能力。该项目汇集了两个具有互补专业知识的小组：一个在耐药性方面有记录的寄生虫学实验室和一个在离子和代谢物运输系统功能表征方面有记录的电生理学实验室。这两个团体都成功地合作过。该项目涉及PfCRT变体的选择，这些变体赋予恶性疟原虫对不同药物的反应变化，PfCRT变体在非洲爪蟾卵母细胞中的功能表达，PfCRT介导电流的底物特异性的研究，PfCRT在铁运输中的作用，使用放射性示踪剂的运输研究，以及活细胞成像。深入了解PfCRT的结构和功能对于维持喹啉类抗疟药物的临床疗效以及制定有效的策略来抑制PfCRT的转运功能至关重要。

Drug resistance remains a pending problem in the control of malaria. Of particular concern is the reduced responsiveness of the human malaria parasite Plasmodium falciparum to quinolone antimalarial drugs. Quinoline derivatives have been used in malaria chemotherapy for more than a century. They are still indispensable, serving as partner drugs to artemisinin derivatives, which as artemisinin combination therapy comprise the current mainstay of malaria chemotherapy. A gene frequently contributing to response variations to quinolines, but also to a large number of structurally unrelated bioactive compounds, is pfcrt encoding a drug/metabolite carrier system. The objective of this project is i) to identify the natural substrate(s) of PfCRT; ii) to study how PfCRT has evolved from a metabolite carrier to a drug transporting system; iii) to develop tools to predict how PfCRT will mutate in the future when exposed to new drug challenges; and iv) to explore whether PfCRT can acquire a multi-drug resistance capability. The project brings together two groups with complementary expertise: a parasitology laboratory with a track record in drug resistance and an electrophysiology laboratory with a track record in the functional characterization of ion and metabolite transport systems. Both groups have successfully worked together. The project involves selection of PfCRT variants that confer response variations to diverse drugs in P. falciparum, the functional expression of PfCRT variants in Xenopus laevis oocytes, the investigation of the substrate specificity of PfCRT-mediated currents, the role of PfCRT in iron transport, transport studies using radioactive tracers, and live cell imaging. In depth knowledge about the structure and function of PfCRT will be crucial to efforts to maintain the clinical efficacy of quinoline antimalarial drugs and to develop effective strategies aimed at inhibiting the transport functions of PfCRT.