Biology subjects

Diagana, T. T.

Publications and source records attributed to Diagana, T. T..

3 recordsLinked to original sources

bioRxiv2022

A conserved metabolic signature associated with response to fast-acting antimalarial agents

Characterizing the mode of action of antimalarial compounds that emerge from high-throughput phenotypic screens is central to understanding how parasite resistance to these drugs can emerge. Here, we have employed untargeted metabolomics to inform on the mechanism of action of antimalarial leads with different speed of kill profiles being developed by the Novartis Institute of Tropical Diseases (NITD). Time-resolved global changes in malaria parasite metabolite profiles upon drug treatment were quantified using liquid chromatography-based mass spectrometry (LC-MS) and compared to untreated controls. Using this approach, we confirmed previously reported metabolomics profiles of the fast-killing (2.5h) drug dihydroartemisinin (DHA) and the slower killing atovaquone (ATQ). A slow acting antimalarial lead from NITD of imidazolopiperazine (IZP) class, GNF179, elicited little or no discernable metabolic change in malaria parasites in the same 2.5h window of drug exposure. In contrast, fast killing drugs, DHA and the spiroindolone (NITD246) elicited similar metabolomic profiles both in terms of kinetics and content. DHA and NITD246 induced peptide losses consistent with disruption of haemoglobin catabolism and also interfered with the pyrimidine biosynthesis pathway. Two members of the recently described novel class of antimalarial agents of the 5-aryl-2-amino-imidazothiadiazole (ITD) class also exhibited a fast-acting profile that also featured peptide losses indicative of disrupted haemoglobin catabolism. Our screen demonstrates that structurally unrelated, fast acting antimalarial compounds generate similar biochemical signatures in Plasmodium pointing to a common mechanism associated with rapid parasite death. Our study describes a potential biochemical signature that may serve to identify other fast acting drug candidates. ImportanceIn malaria drug discovery, understanding the mode of action of lead compounds is important as it helps in predicting the potential emergence of drug resistance in the field when these drugs are eventually deployed. In this study, we have employed metabolomics technologies to characterize the potential targets of antimalarial drug candidates in the developmental pipeline at NITD. We show that NITD fast acting leads belonging to spiroindolone and imidazothiadiazole class induce a common biochemical theme in drug exposed malaria parasites which is similar to another fast acting, clinically available drug, DHA. These biochemical features which are absent in a slower acting NITD lead (GNF17) point to haemoglobin digestion and inhibition of the pyrimidine pathway as potential action points for these drugs. These biochemical themes can be used to identify fast drug candidates of similar profiles in future drug discovery programs.

microbiology↗

bioRxiv2022

Transcriptional profiling of hepatocytes infected with the replicative form of the malaria parasite Plasmodium cynomolgi

The zoonotic simian parasite Plasmodium cynomolgi develops into replicating schizonts and dormant hypnozoites during the infection of hepatocytes and is used as a model organism to study relapsing malaria. We previously reported the transcriptional profiling of P. cynomolgi liver stages and revealed many important biological features of the parasite (Bertschi et al., Elife, 2018; Voorberg-van der Wel et al., Elife, 2017) but left out the host response to malaria infection. Here, we used our published RNA sequencing data to quantify the expression of host genes in rhesus macaque hepatocytes infected with P. cynomolgi in comparison to either cells from uninfected samples or uninfected bystander cells. Although the dataset could not be used to resolve the transcriptional profile of hypnozoite-infected hepatocytes, it provided a snapshot of the host response to liver stage schizonts and identified specific host pathways that are modulated during malaria infection. This study constitutes a valuable resource characterizing the hepatocyte response to P. cynomolgi infection and provides a framework to build on future research that aims at understanding hepatocyte-parasite interactions during relapsing malaria infection.

microbiology↗

bioRxiv2019

Targeting the trypanosome kinetochore with CLK1 protein kinase inhibitors

The kinetochore is a macromolecular structure that assembles on the centromeres of chromosomes and provides the major attachment point for spindle microtubules during mitosis. In Trypanosoma brucei the proteins that make up the kinetochore are highly divergent, with the inner kinetochore comprising at least 20 distinct and essential proteins (KKT1-20) that include four protein kinases, CLK1 (KKT10), CLK2 (KKT19), KKT2 and KKT3. We performed a phenotypic screen of T. brucei bloodstream forms with a Novartis kinase-focused inhibitor library, which identified a number of selective inhibitors with potent pan-kinetoplastid activity. Deconvolution of an amidobenzimidazole series using a selection of 37 T. brucei mutants that over-express known essential protein kinases identified CLK1 as the primary target. Biochemical studies show that the irreversible competitive inhibition of CLK1 is dependent on a Michael acceptor forming an irreversible bond with C215 in the ATP binding pocket, a residue that is not present in human CLK1, thereby providing selectivity. Chemical inhibition of CLK1 impairs inner kinetochore recruitment and compromises cell cycle progression, leading to cell death. We show that KKT2 is a substrate for CLK1 and identify phosphorylation of S508 to be essential for KKT2 function and for kinetochore assembly. We propose that CLK1 is part of a novel signalling cascade that controls kinetochore function via phosphorylation of the inner kinetochore protein kinase KKT2. This work highlights a novel drug target for trypanosomatid parasitic protozoa and a new chemical tool for investigating the function of their divergent kinetochores.

microbiology↗