4E Interacting Protein as a Potential Novel Drug Target for Nucleoside Analogues in Trypanosoma brucei

Abstract

Human African trypanosomiasis is a neglected parasitic disease for which the current treatment options are quite limited. Trypanosomes are not able to synthesize purines de novo and thus solely depend on purine salvage from the host environment. This characteristic makes players of the purine salvage pathway putative drug targets. The activity of known nucleoside analogues such as tubercidin and cordycepin led to the development of a series of C7-substituted nucleoside analogues. Here, we use RNA interference (RNAi) libraries to gain insight into the mode-of-action of these novel nucleoside analogues. Whole-genome RNAi screening revealed the involvement of adenosine kinase and 4E interacting protein into the mode-of-action of certain antitrypanosomal nucleoside analogues. Using RNAi lines and gene-deficient parasites, 4E interacting protein was found to be essential for parasite growth and infectivity in the vertebrate host. The essential nature of this gene product and involvement in the activity of certain nucleoside analogues indicates that it represents a potential novel drug target.

The EIF4E1-4EIP cap-binding complex of Trypanosoma brucei interacts with the terminal uridylyl transferase TUT3

“…One observation, however, suggests that EIF4E1 has an independent function; unlike 4EIP, we were unable to obtain procyclic trypanosomes lacking EIF4E1 [ 35 ]. Apart from this, Mabille et al highlighted that 4EIP is essential for in vivo infectivity in the vertebrate host, as evidenced by a failure to detect 4EIP KO parasites after one week of infection [ 39 ]; immunosuppressive treatment could not rescue the defect.…”

Nucleoside analogues for the treatment of animal trypanosomiasis

“…While drug discovery initiatives for HAT have stagnated with the recent implementation of fexinidazole( Lindner et al, 2020 ) and the Phase-II/III clinical progression of acoziborole, the treatment of animal trypanosomiasis still relies on drugs causing severe local reactions as well as systemic side-effects and the further spread of drug resistance( Chitanga et al, 2011 ; Richards et al, 2021 ). Based on the exclusive dependency of trypanosomes on purine salvage, we recently explored several series of nucleoside analogues, some of which are highly effective for the treatment of second-stage sleeping sickness( Hulpia et al, 2019b ; Mabille et al, 2021 ). Given the current more pressing need for novel compounds for the treatment of AT, this study aimed at redirecting several promising nucleoside analogues for HAT towards animal trypanosomes.…”

“…1 ) was tested for in vitro and in vivo activity against the most pathogenic animal trypanosomes. Experimental details regarding the chemical synthesis have been described elsewhere( Hulpia et al, 2019a , 2019b , 2020a , 2020b ; Mabille et al, 2021 ). Purity of all nucleoside analogues was >95%, as assayed via analytical LC/MS (UV-integration), of which the methods are as described before( Hulpia et al, 2020a ).…”

“…Compounds 15 (FH10677) and 16 (FH10679) are 2′-deoxytubercidin analogues with a bromide substitution at C-7 for compound 16 . Compound codes in original publication: (Tubercidin (1), TH1008 (13), TH1003 (31)) [( Hulpia et al, 2019a )], FH6367 (4) [( Mabille et al, 2021 )], FH9531 (36) [( Hulpia et al, 2020a )], (3′-deoxytubercidin (9), FH7429_UP (10), FH10677 (11), FH10679 (12)) [( Hulpia et al, 2019b )], (FH8517 (7), FH8470 (8), FH8496 (9), FH8505 (12), FH10659 (16)) [( Hulpia et al, 2020b )]. …”

Genome-scale RNAi screens in African trypanosomes

“…Another RIT-seq screen assisted in identifying a trypanosomal peptidase (CBP) that activates a class of veterinary oxaboroles [44]. Three distinct genome-scale RNAi screens have identified metabolism of adenosine analogues by adenosine kinase; first in a screen to probe a density sensing mechanism [45] (see below), and more recently in screens for resistance to potentially therapeutic adenosine analogues [23,46]. As noted above, drug metabolism is thought to promote the intracellular accumulation of toxic metabolites.…”