Biology subjects

Calderano, S. G.

Publications and source records attributed to Calderano, S. G..

3 recordsLinked to original sources

bioRxiv2026

Reduced levels of inositol hexakisphosphate kinase (IP6K) impair life-cycle transitions and the intracellular development of Trypanosoma cruzi within human cardiomyocytes

Trypanosoma cruzi is the etiological agent of Chagas disease. During its life cycle, T. cruzi undergoes several key differentiation processes that are essential for its survival. The precise mechanisms that regulate these processes remain elusive, and any interference in this cycle would represent a breakthrough in the development of effective therapy against Chagas disease. Here, after depleting a single IP6K allele of T. cruzi, we observed that key differentiation processes (metacyclogenesis, amastigogenesis and trypomastigogenesis) were profoundly impaired. Epimastigote forms of IP6K-deficient T. cruzi exhibited morphological alterations and reduced metacyclogenesis. IP6K-deficient metacyclic forms had reduced infective potential in human cardiomyocytes. IP6K-deficient amastigote forms showed impaired ability to transform into trypomastigotes, with most of the population egressing from human cardiomyocytes without completing trypomastigogenesis. Together, our results suggest that IP6K is critical to sustain the T. cruzi life cycle. Since disruption of both IP6K alleles was lethal and the primary structure of IP6K shares only [~]25% similarity with its human homolog, this kinase emerges as a promising target for drug development against Chagas disease. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=153 HEIGHT=200 SRC="FIGDIR/small/700787v2_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@1cb37f0org.highwire.dtl.DTLVardef@c59fb8org.highwire.dtl.DTLVardef@791cb7org.highwire.dtl.DTLVardef@14c68fd_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2025

Stage-Specific MCM Protein Expression in Trypanosoma cruzi: Insights Into Metacyclogenesis and G1 Arrested epimastigotes.

Trypanosoma cruzi is a protozoan parasite that is the etiological agent of Chagas disease, which is endemic to Latin America with reported cases in non-endemic regions such as Europe, Asia, and Oceania due to migration. During its lifecycle, T. cruzi alternates between replicative and non-replicative infective lifeforms. Metacyclogenesis is the most studied transition in which replicative epimastigotes differentiate into infective metacyclic trypomastigotes inside the gut of the triatomine vector. This early-branching organism presents a divergent pre-replication complex (pre-RC) where the only conserved component is the MCM2-7 protein family. Given the role of pre-RC components in cell cycle regulation, we investigated whether MCM expression and location could be involved in proliferation control in epimastigotes and during metacyclogenesis. Our findings reveal that MCMs are consistently expressed and localized to the nucleus throughout the epimastigote cell cycle, including in G1/G0-arrested cells. However, MCM proteins are degraded during metacyclogenesis as cells enter the G0 state, marking the transition to replication arrest. Therefore, epimastigotes arrested in G1/G0 can either maintain MCM expression and resume the cell cycle when conditions become favorable, or they can undergo metacyclogenesis, exiting the cell cycle and entering a G0 state, where MCMs are degraded as part of the replication repression mechanism.

cell biology↗

bioRxiv2021

{-}{-} Histone H2B.V demarcates strategic regions in the Trypanosoma cruzi genome, associates with a bromodomain factor and affects parasite differentiation and host cell invasion

Histone variants play a crucial role in chromatin structure organization and gene expression. Trypanosomatids have an unusual H2B variant (H2B.V) that is known to dimerize with the variant H2A.Z generating unstable nucleosomes. Previously, we found that H2B.V protein is enriched in nonreplicative life forms of Trypanosoma cruzi, suggesting that this variant may contribute to the differences in chromatin structure and global transcription rates observed among parasite life forms. Here, we performed the first genome-wide profiling of histone localization in T. cruzi using replicative and nonreplicative life forms, and we found that H2B.V was preferentially located at the edges of divergent switch regions, which encompass putative transcriptional start regions; at some tDNA loci; and between the conserved and disrupted genome compartments, mainly at trans-sialidase, mucin and MASP genes. Remarkably, the chromatin of nonreplicative forms was depleted of H2B.V-enriched peaks in comparison to replicative forms. Interactome assays indicated that H2B.V associated specifically with H2A.Z, bromodomain factor 2, nucleolar proteins and a histone chaperone, among others. Parasites expressing reduced H2B.V levels were associated with higher rates of parasite differentiation and mammalian cell infectivity. Taken together, H2B.V demarcates critical genomic regions and associates with regulatory chromatin proteins, suggesting a scenario wherein local chromatin structures associated with parasite differentiation and invasion are regulated during the parasite life cycle. Author SummaryTrypanosomatids have to adapt to different environmental conditions, changing their morphology, gene expression and metabolism. These organisms have many unique features in terms of gene expression regulation. The genomic organization includes polycistronic regions with the absence of well-defined transcription start sites. In T. brucei, histone variants mark the start and ending sites of transcription; however, little is known about whether these proteins change their genome location, expression levels and interactors along life forms and what the impact is of these changes on parasite differentiation and infection. In T. cruzi, the causative agent of Chagas disease, we previously found that the histone variant of H2B is enriched in nonreplicative and infective forms, suggesting that this variant may contribute to the differences in chromatin structure and global transcription rates observed among these life forms. Here, we aimed to go one step further and performed the first histone ChIP-seq analysis in T. cruzi, in which we found that H2B.V was enriched at divergent strand switch regions, some tDNA loci and other critical genomic regions associated with T. cruzi genome compartments. We found that H2B.V interacts with a bromodomain factor, suggesting an intricate network involving chromatin acetylation around H2B.V enriched sites. Moreover, parasites expressing reduced H2B.V levels were associated with higher rates of differentiation and mammalian cell infectivity.

microbiology↗