Characterization of Schistosoma mansoni histone post-translational modifications under the effect of histone deacetylase inhibitors

Abstract

The parasite Schistosoma mansoni has a complex life cycle involving an intermediate host and a definitive host. Their diverse phenotypes are orchestrated by a large genome (363 megabases) and by epigenetic mechanisms such as histone post-translational modifications that regulate the activity of chromatin. Modification of chromatin at the histone amino-terminal tail by acetylation regulates transcription, repair, replication and DNA condensation in the cell. The class I Histone Deacetylases (HDACs) has been described in the parasite, its expression being detected at different stages of the cycle; inhibition of HDACs with Trichostatin A (TSA) has been reported to result in hyperacetylation of histones, enhanced activity of caspase 3/7 and induction of apoptosis. In order to identify genes that have the promoter region controlled by histone acetylation, we evaluated in preliminary experiments the overall profile of gene expression of schistosomula under the influence of HDAC inhibitor TSA in a time course experiment, using microarrays. This made it possible to identify for example the modification of expression of genes related to DNA repair and replication and protein synthesis, pointing to a set of genes as possible targets of regulation by histone acetylation. With these preliminary data, this project proposes to study the interaction of acetylated histone with the promoter of differentially expressed candidate genes, using chromatin immunoprecipitation techniques. This will allow characterization of the regulation of chromatin by this parasite's epigenetic mechanism under the effect of HDACs inhibition. In parallel, we have confirmed in preliminary experiments by western blot an increase in chromatin acetylation following treatment with inhibitors of HDAC, however the detailed histone modifications in this physiological situation remain to be identified. We intend to analyze by mass spectrometry the amino-terminal tail of S. mansoni histones in order to identify the histone code after treatment with HDAC inhibitor in adult worms and schistosomula. In this way, we intend to contribute to the knowledge of regulation of chromatin and gene expression of the parasite, unraveling epigenetic mechanisms involving histone acetylation. (AU)