Histone deacetylase inhibition modulates histone acetylation at gene promoter regions and affects genome-wide gene transcription in Schistosoma mansoni

Abstract

BackgroundSchistosomiasis is a parasitic disease infecting hundreds of millions of people worldwide. Treatment depends on a single drug, praziquantel, which kills the Schistosoma spp. parasite only at the adult stage. HDAC inhibitors (HDACi) such as Trichostatin A (TSA) induce parasite mortality in vitro (schistosomula and adult worms), however the downstream effects of histone hyperacetylation on the parasite are not known.Methodology/Principal findingsTSA treatment of adult worms in vitro increased histone acetylation at H3K9ac and H3K14ac, which are transcription activation marks, not affecting the unrelated transcription repression mark H3K27me3. We investigated the effect of TSA HDACi on schistosomula gene expression at three different time points, finding a marked genome-wide change in the transcriptome profile. Gene transcription activity was correlated with changes on the chromatin acetylation mark at gene promoter regions. Moreover, combining expression data with ChIP-Seq public data for schistosomula, we found that differentially expressed genes having the H3K4me3 mark at their promoter region in general showed transcription activation upon HDACi treatment, compared with those without the mark, which showed transcription down-regulation. Affected genes are enriched for DNA replication processes, most of them being up-regulated. Twenty out of 22 genes encoding proteins involved in reducing reactive oxygen species accumulation were down-regulated. Dozens of genes encoding proteins with histone reader motifs were changed, including SmEED from the PRC2 complex. We targeted SmEZH2 methyltransferase PRC2 component with a new EZH2 inhibitor (GSK343) and showed a synergistic effect with TSA, significantly increasing schistosomula mortality.Conclusions/SignificanceGenome-wide gene expression analyses have identified important pathways and cellular functions that were affected and may explain the schistosomicidal effect of TSA HDACi. The change in expression of dozens of histone reader genes involved in regulation of the epigenetic program in S. mansoni can be used as a starting point to look for possible novel schistosomicidal targets.

The repositioning of epigenetic probes/inhibitors identifies new anti-schistosomal lead compounds and chemotherapeutic targets

“…These hits consisted of 5 compounds targeting epigenetic readers, 6 targeting epigenetic writers and 3 targeting epigenetic erasers. Reassuringly, GSK343 was identified as a hit in these screens, supporting previous anti-schistosomal investigations [61] and providing further confidence in the results obtained for the additional EPs and EIs. In one (out of three) JQ1 replicate screens, the motility result was not considered a hit as the value fell above the ‘hit’ cut-off (−0.35).…”

Epigenetic and parasitological parameters are modulated in EBi3-/- mice infected with Schistosoma mansoni

“…In our study, this machinery was downregulated in male parasites recovered from EBi3 -/-I mice due to decreased SmMBD expression; SmHDAC8 expression levels revealed only a loss of sex-specific function in worms recovered from EBi3 -/-I mice. Motility and viability of schistosomula and adults may also be affected by the absence of histone deacetylase activity [43]. SmHDAC1 expression levels revealed a notable difference between females recovered from WT mice and females recovered from EBi3 -/mice, and males and female parasites recovered from EBi3 -/-I mice gained sex-specific functions.…”

Inhibition of histone methyltransferase EZH2 in Schistosoma mansoni in vitro by GSK343 reduces egg laying and decreases the expression of genes implicated in DNA replication and noncoding RNA metabolism

“…In our group, we have recently identified a set of genes differentially expressed in schistosomula exposed to TSA in culture [ 15 ], which are genes associated with DNA replication, recombination and repair, cell cycle and cell death. Interestingly, a network of genes with altered expression related to cell death was identified [ 15 ], among which the Embryonic Ectoderm Development (EED) gene was present; EED expression was strongly suppressed by TSA treatment [ 15 ].…”

“…In our group, we have recently identified a set of genes differentially expressed in schistosomula exposed to TSA in culture [ 15 ], which are genes associated with DNA replication, recombination and repair, cell cycle and cell death. Interestingly, a network of genes with altered expression related to cell death was identified [ 15 ], among which the Embryonic Ectoderm Development (EED) gene was present; EED expression was strongly suppressed by TSA treatment [ 15 ]. EED encodes a regulatory protein that is required for the catalytic activity of the histone methyltransferase EZH2 enzyme, the subunit of polycomb repressor complex 2 (PRC2) that is responsible for trimethylation of histone H3 lysine 27 (H3K27me3) and inhibition of gene transcription [ 16 ].…”

“…EED encodes a regulatory protein that is required for the catalytic activity of the histone methyltransferase EZH2 enzyme, the subunit of polycomb repressor complex 2 (PRC2) that is responsible for trimethylation of histone H3 lysine 27 (H3K27me3) and inhibition of gene transcription [ 16 ]. Inhibition of EED expression by TSA led us to test the hypothesis that the decrease in the activity of PRC2 would be related to the death of the parasites [ 15 ]. We therefore targeted the S .…”