Department of Microbiology, Immunology, & Tropical Medicine, The George Washington University, 2300 Eye Street NW, Ross Hall, Room 522, Washington, DC20037, USA.
Parasitology. 2021 Sep;148(10):1143-1150. doi: 10.1017/S0031182021000317. Epub 2021 Feb 17.
Trypanothione is the primary thiol redox carrier in Trypanosomatids whose biosynthesis and utilization pathways contain unique enzymes that include suitable drug targets against the human parasites in this family. Overexpression of the rate-limiting enzyme, γ-glutamylcysteine synthetase (GSH1), can increase the intracellular concentration of trypanothione. Melarsoprol directly inhibits trypanothione and has predicted the effects on downstream redox biology, including ROS management and dNTP synthesis that require further investigation. Thus, we hypothesized that melarsoprol treatment would inhibit DNA synthesis, which was tested using BrdU incorporation assays and cell cycle analyses. In addition, we analysed the effects of eflornithine, which interfaces with the trypanothione pathway, fexinidazole, because of the predicted effects on DNA synthesis, and pentamidine as an experimental control. We found that melarsoprol treatment resulted in a cell cycle stall and a complete inhibition of DNA synthesis within 24 h, which were alleviated by GSH1 overexpression. In contrast, the other drugs analysed had more subtle effects on DNA synthesis that were not significantly altered by GSH1 expression. Together these findings implicate DNA synthesis as a therapeutic target that warrants further investigation in the development of antitrypanosomal drugs.
三价氮烯是原生动物中的主要硫醇氧化还原载体，其生物合成和利用途径包含独特的酶，其中包括针对该家族人体寄生虫的合适药物靶点。限速酶γ-谷氨酰半胱氨酸合成酶（GSH1）的过表达可以增加三价氮烯的细胞内浓度。米替福新直接抑制三价氮烯，并预测对下游氧化还原生物学有影响，包括 ROS 管理和 dNTP 合成，这需要进一步研究。因此，我们假设米替福新治疗会抑制 DNA 合成，这是通过 BrdU 掺入测定和细胞周期分析来测试的。此外，我们分析了依氟鸟氨酸的影响，依氟鸟氨酸与三价氮烯途径相互作用，非达霉素，因为它对 DNA 合成有预测影响，以及戊双脒作为实验对照。我们发现米替福新治疗导致细胞周期停滞和 DNA 合成在 24 小时内完全抑制，GSH1 过表达可缓解这种抑制。相比之下，分析的其他药物对 DNA 合成的影响更为微妙，GSH1 表达并未显著改变。这些发现共同表明 DNA 合成是一个治疗靶点，值得在开发抗原生动物药物方面进一步研究。
