The antischistosomal potential of GSK-J4, an H3K27 demethylase inhibitor: insights from molecular modeling, transcriptomics and in vitro assays

Abstract

Background Schistosomiasis chemotherapy is largely based on praziquantel (PZQ). Although PZQ is very safe and tolerable, it does not prevent reinfection and emerging resistance is a primary concern. Recent studies have shown that the targeting of epigenetic machinery in Schistosoma mansoni may result in severe alterations in parasite development, leading to death. This new route for drug discovery in schistosomiasis has focused on classes of histone deacetylases (HDACs) and histone acetyltransferases (HATs) as epigenetic drug targets. Schistosoma histone demethylases also seem to be important in the transition of cercariae into schistosomula, as well as sexual differentiation in adult worms. Methods The Target-Pathogen database and molecular docking assays were used to prioritize the druggability of S. mansoni histone demethylases. The transcription profile of Smp_03400 was re-analyzed using available databases. The effect of GSK-J4 inhibitor in schistosomula and adult worms’ motility/viability/oviposition was assessed by in vitro assays. Ultrastructural analysis was performed on adult worms exposed to GSK-J4 by scanning electron microscopy, while internal structures and muscle fiber integrity was investigated by confocal microscopy after Langeronʼs carmine or phalloidin staining. Results The present evaluation of the potential druggability of 14 annotated S. mansoni demethylase enzymes identified the S. mansoni ortholog of human KDM6A/UTX (Smp_034000) as the most suitable druggable target. In silico analysis and molecular modeling indicated the potential for cofactor displacement by the chemical probe GSK-J4. Our re-analysis of transcriptomic data revealed that Smp_034000 expression peaks at 24 h in newly transformed schistosomula and 5-week-old adult worms. Moreover, this gene was highly expressed in the testes of mature male worms compared to the rest of the parasite body. In in vitro schistosome cultures, treatment with GSK-J4 produced striking effects on schistosomula mortality and adult worm motility and mortality, as well as egg oviposition, in a dose- and time-dependent manner. Unexpectedly, western blot assays did not demonstrate overall modulation of H3K27me3 levels in response to GSK-J4. Confocal and scanning electron microscopy revealed the loss of original features in muscle fibers and alterations in cell-cell contact following GSK-J4 treatment. Conclusions GSK-J4 presents promising potential for antischistosomal control; however, the underlying mechanisms warrant further investigation.

Long non-coding RNA levels can be modulated by 5-azacytidine in Schistosoma mansoni

“…It is now clear that epigenetic processes play important roles on schistosomes [81][82][83] . In fact, epigenetic mechanisms participate in schistosome phenotypic plasticity 84,85 , in egg production and adult worm viability 34,86,87 as well as in schistosomula survival [88][89][90][91][92] . DNA methylation, one of the most studied epigenetic mechanisms, has been detected in S. mansoni 15 , although the significance of DNA cytosine methylation (5mC) in this parasite has been somewhat controversial [93][94][95] .…”

Identification of 6-(piperazin-1-yl)-1,3,5-triazine as a chemical scaffold with broad anti-schistosomal activities

“…Careful regulation of histone methylation/demethylation is essential for developmental progression of the major human pathogen S. mansoni 10 , 24 , 25 , 36 . Because of this realisation, exploration of the histone methylation machinery for druggable targets has been actively pursued 10 , 28 , 29 .…”

A novel series of putative Brugia malayi histone demethylase inhibitors as potential anti-filarial drugs

“…mansoni) , a parasitic nematode distinct from B . malayi , presumably through inhibition of demethylase activity, although a direct effect on parasite histone methylation has not been demonstrated [ 6 ]. Interestingly, treatment of parasites with our active compounds lead to modification of relevant methylated histones while treatment with GSK-J4 does not, as reported for S. mansoni [ 6 ].…”

“…malayi , presumably through inhibition of demethylase activity, although a direct effect on parasite histone methylation has not been demonstrated [ 6 ]. Interestingly, treatment of parasites with our active compounds lead to modification of relevant methylated histones while treatment with GSK-J4 does not, as reported for S. mansoni [ 6 ]. In order to gain a better understanding of the mode of action of this class of compounds we performed a global RNA sequencing analysis of drug treated parasites.…”