Department of Pathology, Microbiology, and Immunology, University of Nebraska Medical Center, Omaha, Nebraska, USA.
Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska, USA.
mSphere. 2024 Nov 21;9(11):e0037124. doi: 10.1128/msphere.00371-24. Epub 2024 Oct 22.
Malaria remains a global health burden, killing over half a million people each year. Decreased therapeutic efficacy to artemisinin, the most efficacious antimalarial, has been detected in sub-Saharan Africa, a worrying fact given that over 90% of deaths occur on this continent. Mutations in Kelch13 are the most well-established molecular marker for artemisinin resistance, but these do not explain all artemisinin-resistant isolates. Understanding the biological underpinnings of drug resistance is key to curbing the emergence and spread of artemisinin resistance. Artemisinin-mediated non-specific alkylation leads to the accumulation of misfolded and damaged proteins and activation of the parasite unfolded protein response (UPR). In addition, the parasite proteasome is vital to artemisinin resistance, as we have previously shown that chemical inhibition of the proteasome or mutations in the β2 proteasome subunit increase parasite susceptibility to dihydroartemisinin (DHA), the active metabolite of artemisinins. Here, we investigate parasites with mutations at the Kelch13 and/or 19S and 20S proteasome subunits with regard to UPR regulation and proteasome activity in the context of artemisinin resistance. Our data show that perturbing parasite proteostasis kills parasites, early parasite UPR signaling dictates DHA survival outcomes, and DHA susceptibility correlates with impairment of proteasome-mediated protein degradation. Importantly, we show that functional proteasomes are required for artemisinin resistance in a Kelch13-independent manner, and compound-selective proteasome inhibition demonstrates why artemisinin-resistant Kelch13 mutants remain susceptible to the related antimalarial peroxide OZ439. These data provide further evidence for targeting the parasite proteasome and UPR to overcome existing artemisinin resistance.IMPORTANCEDecreased therapeutic efficacy represents a major barrier to malaria treatment control strategies. The malaria proteasome and accompanying unfolded protein response are crucial to artemisinin resistance, revealing novel antimalarial therapeutic strategies.
疟疾仍然是全球健康的负担，每年导致超过 50 万人死亡。在撒哈拉以南非洲地区已经检测到青蒿素（最有效的抗疟药物）的治疗效果降低，这是一个令人担忧的事实，因为超过 90%的死亡发生在这个大陆上。Kelch13 的突变是青蒿素耐药性最成熟的分子标志物，但这些并不能解释所有青蒿素耐药株。了解耐药性的生物学基础是遏制青蒿素耐药性的出现和传播的关键。青蒿素介导的非特异性烷基化导致错误折叠和受损蛋白质的积累，并激活寄生虫未折叠蛋白反应 (UPR)。此外，寄生虫蛋白酶体对于青蒿素耐药性至关重要，因为我们之前已经表明，蛋白酶体的化学抑制或β2 蛋白酶体亚基的突变会增加寄生虫对二氢青蒿素（青蒿素的活性代谢物）的敏感性。在这里，我们研究了 Kelch13 和/或 19S 和 20S 蛋白酶体亚基发生突变的寄生虫，以了解它们在青蒿素耐药性背景下的 UPR 调节和蛋白酶体活性。我们的数据表明，扰乱寄生虫的蛋白质稳态会杀死寄生虫，早期寄生虫 UPR 信号决定了 DHA 的生存结果，并且 DHA 的敏感性与蛋白酶体介导的蛋白质降解受损相关。重要的是，我们表明功能性蛋白酶体以 Kelch13 独立的方式是青蒿素耐药性所必需的，并且化合物选择性蛋白酶体抑制证明了为什么青蒿素耐药性 Kelch13 突变体仍然对相关的抗疟过氧化物 OZ439 敏感。这些数据为针对寄生虫蛋白酶体和 UPR 提供了进一步的证据，以克服现有的青蒿素耐药性。
