DNA methylation, 3D genome organization and gene expression during Trichomonas vaginalis: host interaction

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DNA methylation, 3D genome organization and gene expression during Trichomonas vaginalis: host interaction ABSTRACT Trichomonas vaginalis is a common sexually transmitted parasite that colonizes the human urogenital tract causing infections that range from asymptomatic to highly inflammatory. Chronic infections can lead to severe complications such as infertility, premature birth during pregnancy, increases the risk of acquiring HIV, cervical cancer and aggressive prostate cancer. Hence, understanding how the process of infection in Trichomonas parasite is regulated remains an important goal in parasitology research and human health. Host: parasite interaction is regulated by changes in gene expression, but it is still largely unknown how these changes in transcriptional profiles are controlled as very few transcriptional regulatory elements have been described. Our recent works highlighted the importance of epigenetics in the regulation of transcription and possible role in parasite pathogenesis. Specifically, we analyzed the abundance of DNA methylation demonstrating that N6-methyladenine (6mA), and not 5‐methylcytosine (5mC), is the main DNA methylation mark in T. vaginalis. Genome-wide distribution of 6mA reveals that this mark is enriched at intergenic regions, with a preference for certain superfamilies of DNA transposable elements. Interestingly, bioinformatics analysis revealed the presence of transcriptionally active or repressive intervals flanked by 6mA-enriched regions and results from chromatin conformation capture (3C) experiments suggest these 6mA flanked regions are in close spatial proximity. This finding revealed a new role for 6mA in modulating 3D chromatin structure and gene expression in this parasite. Based on these antecedents we now propose that 6mA could be a key regulator of 3D genome architecture by modulating expression of transcriptional- modules of genes during parasite infection. Three-dimensional arrangement of DNA in the nucleus are increasingly seen as key contributors to the regulation of gene expression but studies on how genome structure and nuclear organization influence transcription have so far been limited to a handful of model species. Guided by strong preliminary data, we propose to pursue three specific aims to further analyze the role of 6mA in the regulation of 3D genome conformation and gene expression during the process of parasite attachment to host cells. These results will provide new insights into T. vaginalis epigenetic regulation that may help to understand the mechanisms that lead to parasite adherence and cytotoxicity; key steps toward dissecting the specific outcomes of Trichomonas infection. Importantly, the association of 6mA with chromatin looping is noteworthy because it points to a novel function for this epigenetic mark in eukaryotes with scarce 5mC levels. 1