Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, USA.
Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, USA.
BMC Genomics. 2018 Nov 29;19(1):849. doi: 10.1186/s12864-018-5207-7.
Plasmodium falciparum exhibits resistance to the artemisinin component of the frontline antimalarial treatment Artemisinin-based Combination Therapy in South East Asia. Millions of lives will be at risk if artemisinin resistance (ART-R) spreads to Africa. Single non-synonymous mutations in the propeller region of PF3D7_1343700,"K13" are implicated in resistance. In this work, we use transcriptional profiling to characterize a laboratory-generated k13 insertional mutant previously demonstrated to have increased sensitivity to artemisinins to explore the functional role of k13.
A set of RNA-seq and microarray experiments confirmed that the expression profile of k13 is specifically altered during the early ring and early trophozoite stages of the mutant intraerythrocytic development cycle. The down-regulation of k13 transcripts in this mutant during the early ring stage is associated with a transcriptome advance towards a more trophozoite-like state. To discover the specific downstream effect of k13 dysregulation, we developed a new computational method to search for differential gene expression while accounting for the temporal sequence of transcription. We found that the strongest biological signature of the transcriptome shift is an up-regulation of DNA replication and repair genes during the early ring developmental stage and a down-regulation of DNA replication and repair genes during the early trophozoite stage; by contrast, the expressions of housekeeping genes are unchanged. This effect, due to k13 dysregulation, is antagonistic, such that k13 levels are negatively correlated with DNA replication and repair gene expression.
Our results support a role for k13 as a stress response regulator consistent with the hypothesis that artemisinins mode of action is oxidative stress and k13 as a functional homolog of Keap1 which in humans regulates DNA replication and repair genes in response to oxidative stress.
恶性疟原虫对青蒿素类药物（一线抗疟药物联合疗法中的青蒿素成分）表现出耐药性。如果青蒿素耐药性（ART-R）传播到非洲，数以百万计的生命将面临风险。PF3D7_1343700“K13”螺旋桨区域的单个非同义突变与耐药性有关。在这项工作中，我们使用转录谱分析来描述一个实验室产生的 k13 插入突变体，该突变体先前被证明对青蒿素类药物更敏感，以探索 k13 的功能作用。
一组 RNA-seq 和微阵列实验证实，k13 的表达谱在突变体红细胞内发育周期的早期环和早期滋养体阶段特异性改变。在这个突变体中，k13 转录本在早期环阶段的下调与向更类似于滋养体的状态的转录组前进有关。为了发现 k13 失调的具体下游效应，我们开发了一种新的计算方法，在考虑转录时间序列的情况下搜索差异基因表达。我们发现，转录组转移的最强生物学特征是早期环发育阶段 DNA 复制和修复基因的上调和早期滋养体阶段 DNA 复制和修复基因的下调；相比之下，管家基因的表达不变。这种由于 k13 失调引起的效应是拮抗的，使得 k13 水平与 DNA 复制和修复基因的表达呈负相关。
我们的结果支持 k13 作为应激反应调节剂的作用，这与青蒿素类药物的作用机制是氧化应激以及 k13 作为 Keap1 的功能同源物的假说一致，在人类中，Keap1 调节 DNA 复制和修复基因以应对氧化应激。
