Goldenberg, S. | Search bioRxiv

bioRxiv2023

TcZC3HTTP, a regulatory element that contributes to Trypanosoma cruzi cell proliferation

Post-transcriptional regulation of gene expression is a critical process for adapting and surviving Trypanosoma cruzi, a parasite with a complex life cycle. RNA binding proteins (RBPs) are key players in this regulation, forming ribonucleoprotein complexes (mRNPs) and RNA granules that control transcript stability, localization, degradation, and translation modulation. Understanding the specific roles of individual RBPs is crucial for unraveling the details of this regulatory network. In this study, we generated null mutants of the TcZC3HTTP gene, a specific RBP in the Trypanosoma family, characterized by a C3H zinc finger and a DNAJ domain associated with RNA and protein binding, respectively. Through cell growth assays, we demonstrated that the absence of TcZC3HTTP or the expression of an additional tagged version significantly impacted epimastigote growth, indicating its contribution to cell proliferation. TcZC3HTTP was found to associate with mRNAs involved in cell cycle and division in epimastigotes, while nutritionally stressed parasites exhibited associations with mRNAs coding for other RBPs and rRNA. Furthermore, our analysis of TcZC3HTTP protein partners revealed the presence of several enzymes during normal growth conditions, whereas starvation conditions enriched ribosomal proteins and other RBPs. This study provides insights into the post-transcriptional regulation of gene expression in T. cruzi, highlighting the role of TcZC3HTTP as an RBP involved in cell proliferation and uncovering its versatile functions in different cellular contexts. ImportanceUnderstanding how Trypanosoma cruzi, the causative agent of Chagas disease, regulates gene expression is crucial for developing targeted interventions. In this study, we investigated the role of TcZC3HTTP, an RNA binding protein, in post-transcriptional regulation. Our findings demonstrate that TcZC3HTTP is essential for the growth and proliferation of epimastigotes, a stage of the parasites life cycle. We identified its associations with specific mRNAs involved in cell cycle and division and its interactions with enzymes and other RBPs under normal and starvation conditions. These insights shed light on the regulatory network underlying gene expression in T. cruzi and reveal the multifaceted functions of RBPs in this parasite. Such knowledge enhances our understanding of the parasites biology and opens avenues for developing novel therapeutic strategies targeting post-transcriptional gene regulation in T. cruzi.

microbiology↗

bioRxiv2019

Extracellular vesicle-mediated RNA release in Histoplasma capsulatum

Eukaryotic cells, including fungi, release extracellular vesicles (EVs). These lipid bilayered compartments play essential roles in cellular communication and pathogenesis. EV composition is complex and includes proteins, glycans, pigments, and RNA. RNA classes with putative roles in pathogenesis have been described in EVs produced by fungi. Here we describe the RNA content in EVs produced by the G186AR and G217B strains of Histoplasma capsulatum, an important human fungal pathogen. A total of 124 mRNA were identified in both strains. In this set of RNA classes, 93 transcripts were enriched in EVs from the G217B strain, while 31 enriched in EVs produced by the G186AR strain. This result suggests that there are important strain-specific properties in the mRNA composition of fungal EVs. We also identified short fragments (25-40 long) that were strain-specific, with a greater number of them identified in EVs produced by the G217B strain. Remarkably, the most enriched processes were stress responses and translation. Half of these fragments aligned to the reverse strand of the transcript, suggesting the occurrence of miRNA-like molecules in fungal EVs. We also compared the transcriptome profiles of H. capsulatum with the RNA composition of EVs and no correlation was observed. Altogether, our study provided information about the RNA molecules present in H. capsulatum EVs, and the differences in composition between the G186AR and G217B strains. In addition, we showed that the correlation between the most expressed transcripts in the cell and their presence in the EVs, reinforcing the idea that the RNAs were directed to the EVs by a regulated mechanism.\n\nImportanceExtracellular vesicles (EVs) play important roles in cellular communication and pathogenesis. The RNA molecules in EVs have been implicated in a variety of processes. In pathogenic fungi, EV-associated RNA classes have recently been described; however, only a few studies describing the RNA in fungal EVs are available. An improved knowledge on EV-associated RNA will contribute to the understanding of their role during infection. In this study, we described the RNA content in EVs produced by two isolates of Histoplasma capsulatum. Our results add this important pathogen to the current short list of fungal species with the ability to use EVs for the extracellular release of RNA.

microbiology↗