Possible role of CD38 in lipid homeostasis in the liver of CD-1 mice

Master'sMASTER OF SCIENC

Targeting Plasmodium phosphatidylinositol-4 kinase for the treatment, prevention and elimination of malaria

Achieving the goal of malaria elimination is vitally dependent on identifying validated drug targets that are active across all stages of the Plasmodium lifecycle. Here, we identify phosphatidylinositol-4 kinase (PfPI4K) as the target of the imidazopyrazines, a novel antimalarial compound class that potently inhibits the intracellular development of multiple Plasmodium species at each stage of infection of the vertebrate host. Imidazopyrazines demonstrate potent preventive, therapeutic, and transmission-blocking activity in several rodent malaria models. These compounds are also active against blood-stage field isolates of the major human malaria pathogens, P. falciparum and P. vivax, and inhibit liver stage hypnozoites in the human and simian parasite P. cynomolgi. Evolved resistance, full genome-scanning and genome editing experiments in intra-erythrocytic stages as well as biochemical data, show that imidazopyrazines exert their potent antimalarial activity through interaction with the ATP-binding pocket of the lipid kinase. Inhibition of PfPI4K, alters the intracellular distribution of phosphatidylinositol-4 phosphate, the PI4K product, and interferes with cytokinesis via a Rab11A-dependent pathway. Collectively, our data define PfPI4K as a key Plasmodium vulnerability, opening up new avenues of target-based discovery to identify antimalarial drugs with an ideal pharmacological profile for the prevention, treatment and elimination of malaria

Cladosporin, a fungal metabolite with potent blood and hepatic stage antimalarial activity targets lysyl-tRNA synthetase

Cladosporin, a fungal secondary metabolite, is reported to have a wide spectrum of biological activities. However, its primary target and mechanism of action is not known. Here we report that cladosporin has potent antimalarial activity and elucidate its target as the lysyl-tRNA synthetase in Saccharomyces cerevisiae (KRS1) and Plasmodium falciparum. Haploinsufficiency profiling of S. cerevisiae in the presence of cladosporin identified the krs1/KRS1 strain as hypersensitive, and over-expression of KRS1 leads to resistance. Furthermore, point mutations in the Krs1 Lysine-ATP binding-site also yield resistance. In Plasmodium falciparum addition of cladosporin rapidly inhibits protein synthesis. When plasmodial parasites were cultured in the presence of the compound to force the development of resistance, they responded by amplification of the genomic locus encoding the plasmodial lysyl-tRNA synthetase. Cladosporin inhibits both hepatic as well as blood stage parasite development, shows no cytotoxicity up to high concentrations and is thus an attractive antimalarial agent

Targeting Plasmodium PI(4)K to eliminate malaria.

Achieving the goal of malaria elimination will depend on targeting Plasmodium pathways essential across all life stages. Here we identify a lipid kinase, phosphatidylinositol-4-OH kinase (PI(4)K), as the target of imidazopyrazines, a new antimalarial compound class that inhibits the intracellular development of multiple Plasmodium species at each stage of infection in the vertebrate host. Imidazopyrazines demonstrate potent preventive, therapeutic, and transmission-blocking activity in rodent malaria models, are active against blood-stage field isolates of the major human pathogens P. falciparum and P. vivax, and inhibit liver-stage hypnozoites in the simian parasite P. cynomolgi. We show that imidazopyrazines exert their effect through inhibitory interaction with the ATP-binding pocket of PI(4)K, altering the intracellular distribution of phosphatidylinositol-4-phosphate. Collectively, our data define PI(4)K as a key Plasmodium vulnerability, opening up new avenues of target-based discovery to identify drugs with an ideal activity profile for the prevention, treatment and elimination of malaria

Targeting Plasmodium PI(4)K to eliminate malaria

Achieving the goal of malaria elimination will depend on targeting Plasmodium pathways essential across all life stages. Here we identify a lipid kinase, phosphatidylinositol-4-OH kinase (PI(4)K), as the target of imidazopyrazines, a new antimalarial compound class that inhibits the intracellular development of multiple Plasmodium species at each stage of infection in the vertebrate host. Imidazopyrazines demonstrate potent preventive, therapeutic, and transmission-blocking activity in rodent malaria models, are active against blood-stage field isolates of the major human pathogens P. falciparum and P. vivax, and inhibit liver-stage hypnozoites in the simian parasite P. cynomolgi. We show that imidazopyrazines exert their effect through inhibitory interaction with the ATP-binding pocket of PI(4)K, altering the intracellular distribution of phosphatidylinositol-4-phosphate. Collectively, our data define PI(4)K as a key Plasmodium vulnerability, opening up new avenues of target-based discovery to identify drugs with an ideal activity profile for the prevention, treatment and elimination of malaria

Lead Optimization of Imidazopyrazines: A New Class of Antimalarial with Activity on <i>Plasmodium</i> Liver Stages

Imidazopyridine <b>1</b> was identified from a phenotypic screen against <i>P. falciparum</i> (Pf) blood stages and subsequently optimized for activity on liver-stage schizonts of the rodent parasite <i>P. yoelii</i> (Py) as well as hypnozoites of the simian parasite <i>P. cynomolgi</i> (Pc). We applied these various assays to the cell-based lead optimization of the imidazopyrazines, exemplified by <b>3</b> (KAI407), and show that optimized compounds within the series with improved pharmacokinetic properties achieve causal prophylactic activity <i>in vivo</i> and may have the potential to target the dormant stages of <i>P. vivax</i> malaria

Antimalarial efficacy of MMV390048, an inhibitor of Plasmodium phosphatidylinositol 4-kinase

As part of the global effort toward malaria eradication, phenotypic whole-cell screening revealed the 2-aminopyridine class of small molecules as a good starting point to develop new antimalarial drugs. Stemming from this series, we found that the derivative, MMV390048, lacked cross-resistance with current drugs used to treat malaria. This compound was efficacious against all Plasmodium life cycle stages, apart from late hypnozoites in the liver. Efficacy was shown in the humanized Plasmodium falciparum mouse model, and modest reductions in mouse-to-mouse transmission were achieved in the Plasmodium berghei mouse model. Experiments in monkeys revealed the ability of MMV390048 to be used for full chemoprotection. Although MMV390048 was not able to eliminate liver hypnozoites, it delayed relapse in a Plasmodium cynomolgi monkey model. Both genomic and chemoproteomic studies identified a kinase of the Plasmodium parasite, phosphatidylinositol 4-kinase, as the molecular target of MMV390048. The ability of MMV390048 to block all life cycle stages of the malaria parasite suggests that this compound should be further developed and may contribute to malaria control and eradication as part of a single-dose combination treatment

Antimalarial efficacy of MMV390048, an inhibitor of Plasmodium phosphatidylinositol 4-kinase.

As part of the global effort toward malaria eradication, phenotypic whole-cell screening revealed the 2-aminopyridine class of small molecules as a good starting point to develop new antimalarial drugs. Stemming from this series, we found that the derivative, MMV390048, lacked cross-resistance with current drugs used to treat malaria. This compound was efficacious against all Plasmodium life cycle stages, apart from late hypnozoites in the liver. Efficacy was shown in the humanized Plasmodium falciparum mouse model, and modest reductions in mouse-to-mouse transmission were achieved in the Plasmodium berghei mouse model. Experiments in monkeys revealed the ability of MMV390048 to be used for full chemoprotection. Although MMV390048 was not able to eliminate liver hypnozoites, it delayed relapse in a Plasmodium cynomolgi monkey model. Both genomic and chemoproteomic studies identified a kinase of the Plasmodium parasite, phosphatidylinositol 4-kinase, as the molecular target of MMV390048. The ability of MMV390048 to block all life cycle stages of the malaria parasite suggests that this compound should be further developed and may contribute to malaria control and eradication as part of a single-dose combination treatment