Essential Bromodomain <i>Tc</i> BDF2 as a Drug Target against Chagas Disease

Abstract

<i>Trypanosoma cruzi</i> is a unicellular parasite that causes Chagas disease, which is endemic in the American continent but also worldwide, distributed by migratory movements. A striking feature of trypanosomatids is the polycistronic transcription associated with post-transcriptional mechanisms that regulate the levels of translatable mRNA. In this context, epigenetic regulatory mechanisms have been revealed to be of great importance, since they are the only ones that would control the access of RNA polymerases to chromatin. Bromodomains are epigenetic protein readers that recognize and specifically bind to acetylated lysine residues, mostly at histone proteins. There are seven coding sequences for BD-containing proteins in trypanosomatids, named <i>Tc</i>BDF1 to <i>Tc</i>BDF7, and a putative new protein containing a bromodomain was recently described. Using the Tet-regulated overexpression plasmid p<i>Tc</i>INDEX-GW and CRISPR/Cas9 genome editing, we were able to demonstrate the essentiality of <i>Tc</i>BDF2 in <i>T. cruzi</i>. This bromodomain is located in the nucleus, through a bipartite nuclear localization signal. <i>Tc</i>BDF2 was shown to be important for host cell invasion, amastigote replication, and differentiation from amastigotes to trypomastigotes. Overexpression of <i>Tc</i>BDF2 diminished epimastigote replication. Also, some processes involved in pathogenesis were altered in these parasites, such as infection of mammalian cells, replication of amastigotes, and the number of trypomastigotes released from host cells. In <i>in vitro</i> studies, <i>Tc</i>BDF2 was also able to bind inhibitors showing a specificity profile different from that of the previously characterized <i>Tc</i>BDF3. These results point to <i>Tc</i>BDF2 as a druggable target against <i>T. cruzi</i>.