Tc BDF6 deficiency compromises intracellular amastigote development and infectivity in Trypanosoma cruzi
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Trypanosoma cruzi , the causative agent of Chagas disease, relies on complex gene regulatory mechanisms to adapt to its diverse host environments. Although this parasite lacks canonical transcriptional control, epigenetic regulation plays a pivotal role in modulating gene expression. Bromodomain-containing factors (BDFs), known for recognizing acetylated lysines on histones, have emerged as key regulators of chromatin structure and gene activity. Among the eight predicted BDFs in T. cruzi, Tc BDF6 is part of a TINTIN-like complex with Tc MRGx and Tc MRGBP, homologous to components of the NuA4/TIP60 chromatin remodeling complex. To investigate the function of Tc BDF6, we generated knockout (KO) parasites using CRISPR/Cas9 gene editing. While BDF6-deficient epimastigotes did not exhibit very significative growth differences, the resulting metacyclic trypomastigotes displayed drastically reduced infectivity. Strikingly, once inside host cells, Tc BDF6 deficient parasites differentiated into amastigotes but failed to replicate. This intracellular arrest was partially reversed by episomal re-expression of Tc BDF6. Consistently, BDF6 KO parasites also exhibited impaired infectivity, a defect that was also rescued in the add-back line. Our findings highlight Tc BDF6 as a critical regulator of intracellular parasite development, operating in stages beyond epimastigotes where epigenetic plasticity is essential for host adaptation. The unique, stage-specific phenotype of BDF6 knockouts underscores its functional importance and suggests that bromodomains may represent novel therapeutic targets against T. cruzi .
Author Summary
To survive in the dramatically different environments of its life cycle, Trypanosoma cruzi , the parasite that causes Chagas disease, must finely tune its gene expression. Unlike many organisms, T. cruzi lacks classical transcriptional regulation and instead relies on epigenetic mechanisms. Among the proteins involved in this regulation are bromodomain containing factors, which interpret chemical marks on chromatin. In this study, we focused on Tc BDF6, a bromodomain protein thought to be part of a chromatin remodeling complex. Using CRISPR/Cas9, we disrupted the TcBDF6 gene and discovered that, while the mutant parasites could still form infective stages, they failed to replicate inside host cells. Reintroducing TcBDF6 , it was rescued this defect, confirming its critical role in intracellular development. Our findings highlight the importance of epigenetic control in parasite survival and suggest that bromodomain proteins could be valuable targets for future treatments against Chagas disease.
