A molecular mechanism of artemisinin resistance in Plasmodium falciparum malaria

Abstract

Artemisinins are the corner stone of anti-malarial drugs1. Emergence and spread of resistance to them2–4 raises risk of wiping out recent gains achieved in reducing world-wide malaria burden and threatens future malaria control and elimination on a global level. Genome wide association studies (GWAS) have revealed parasite genetic loci associated with artemisinin resistance5–10. However, there is no consensus on biochemical targets of artemisinin. Whether and how these targets interact with genes identified by GWAS, remains unknown. Here we provide biochemical and cellular evidence that artemisinins are potent inhibitors of Plasmodium falciparum phosphatidylinositol-3-kinase (PfPI3K), revealing an unexpected mechanism of action. In resistant clinical strains, increased PfPI3K was associated with the C580Y mutation in P. falciparum Kelch13 (PfKelch13), a primary marker of artemisinin resistance. Polyubiquitination of PfPI3K and its binding to PfKelch13 were reduced by PfKelch13 mutation, which limited proteolysis of PfPI3K and thus increased levels of the kinase as well as its lipid product phosphatidylinositol 3-phosphate (PI3P). We find PI3P levels to be predictive of artemisinin resistance in both clinical and engineered laboratory parasites as well as across non-isogenic strains. Elevated PI3P induced artemisinin resistance in absence of PfKelch13 mutations, but remained responsive to regulation by PfKelch13. Evidence is presented for PI3P-dependent signaling, where transgenic expression of an additional kinase confers resistance. Together these data present PI3P as the key mediator of artemisinin resistance and the sole PfPI3K as an important target for malaria elimination.

Biology of Malaria Transmission

“…To block transmission, ACT is often combined with the only transmissionblocking drug on the market, Primaquine. However, recent emergence of artemisinin resistance in Southeast Asia asks for urgent evaluation of alternative treatment strategies (Noedl et al 2008;Dondorp et al 2009;Mbengue et al 2015;Straimer et al 2015).Of the five Plasmodium species known to cause malaria in humans, Plasmodium falciparum is lethal and responsible for severe disease pathology and the majority of deaths due to malaria, especially in sub-Saharan Africa. Plasmodium vivax typically causes milder infections than P. falciparum but has a much greater geographical distribution (Gething et al 2012).…”

“…To block transmission, ACT is often combined with the only transmissionblocking drug on the market, Primaquine. However, recent emergence of artemisinin resistance in Southeast Asia asks for urgent evaluation of alternative treatment strategies (Noedl et al 2008;Dondorp et al 2009;Mbengue et al 2015;Straimer et al 2015).…”

Artemisinin resistance, some facts and opinions

“…More recently, a mutation on the K13-Propeller locus has been observed to be associated to DPC in Cambodia [9]; subsequently, additional mutations on the same gene have been observed in other regions in South Asia [10][11][12][13][14][15][16]. This promising marker is currently used in association with DPC to identify ART resistance but both still require a substantial clinical validation.…”

<i>In silico</i> Design of Phosphonic Arginine and Hydroxamic Acid Inhibitors of <i>Plasmodium falciparum</i> M17 Leucyl Aminopeptidase with Favorable Pharmacokinetic Profile

“…For one decade (2006 -2016), survival of millions people at risk of malaria infection relies on the strategy of "ACT", the strength of which remains unable to address the unstoppably growing spread of artemisinin-resistant Plasmodium falciparum (pf) [2,3] for long.…”