Biology subjects

Bermudez, Y.

Publications and source records attributed to Bermudez, Y..

3 recordsLinked to original sources

bioRxiv2025

Virally encoded interleukin-6 (vIL-6) coordinates with human IL-6 to modulate cytokine expression during KSHV infection

Kaposi Sarcoma-Associated Herpesvirus (KSHV) is characterized by its ability to establish lifelong infections that can lead to disease in immunocompromised individuals. Understanding the complex interactions between KSHV, the host cellular machinery, and the immune response is essential for unraveling the mechanisms underlying viral persistence and pathogenesis. KSHV extensively remodels the host gene expression landscape by inducing widespread RNA decay via the viral endoribonuclease SOX. While the vast majority of cellular mRNAs are degraded by SOX, select transcripts including Interleukin 6 (IL-6) escape degradation. Interestingly, KSHV encodes a viral homolog of IL-6, known as viral interleukin-6 (vIL-6). Given the importance of IL-6 for KSHV biology and its ability to escape SOX-mediated decay, we explored how vIL-6 expression is regulated upon KSHV infection. Our data demonstrate that unlike IL-6, vIL-6 3UTR does not provide protection from SOX degradation, yet vIL-6 mRNA steady state levels remain high throughout KSHV lytic cycle, suggesting a distinct transcriptional regulation. To assess the contributions of vIL-6 and IL-6 in modulating host gene expression, inflammatory signaling and KSHV-driven pathogenesis, we used a vIL-6 null viral mutant combined with an IL-6 knock down to perform transcriptomic analyses. This analysis revealed that depletion of IL-6, vIL-6 or both results in distinct alterations of the host gene expression environment, with differential effects on chemokine signaling and related pathways as well as a synergistic effect when both IL-6 and vIL-6 are present. Furthermore, functional assays confirmed vIL-6 alone is sufficient to activate key signaling pathways and pro-inflammatory responses, including the JAK/STAT pathway. Collectively, our findings suggest a mechanistic synergy between vIL-6 and IL-6 that may enhance KSHV-mediated immune modulation and contribute to viral persistence and tumorigenesis.

microbiology↗

bioRxiv2022

Nonstructural protein 1 (nsp1) widespread RNA decay phenotype varies among Coronaviruses

AO_SCPLOWBSTRACTC_SCPLOWExtensive remodeling of the host gene expression environment by coronaviruses nsp1 proteins is a well-documented and conserved piece of the coronavirus-host takeover battle. However, whether and how the underlying mechanism of regulation or the transcriptional target landscape differ amongst coronaviruses remains mostly uncharacterized. In this study we use comparative transcriptomics to investigate the diversity of transcriptional targets between four different coronavirus nsp1 proteins (from MERS, SARS1, SARS2 and 229E). In parallel, we performed Affinity Purification followed by Mass-Spectrometry to identify common and divergent interactors between these different nsp1. For all four nsp1 tested, we detected widespread RNA destabilization, confirming that both - and {beta}-Coronavirus nsp1 broadly affect the host transcriptome. Surprisingly, we observed that even closely related nsp1 showed little similarities in the clustering of genes targeted. Additionally, we show that the RNA targeted by nsp1 from the -CoV 229E partially overlapped with MERS nsp1 targets. Given MERS nsp1 preferential targeting of nuclear transcripts, these results may indicate that these nsp1 proteins share a similar targeting mechanism. Finally, we show that the interactome of these nsp1 proteins differ widely. Intriguingly, our data indicate that the 229E nsp1, which is the smallest of the nsp1 proteins tested here, interacts with the most host proteins, while MERS nsp1 only engaged with a few host proteins. Collectively, our work highlights that while nsp1 is a rather well-conserved protein with conserved functions across different coronaviruses, its precise effects on the host cell is virus specific. SO_SCPLOWIGNIFICANCEC_SCPLOWCoronaviruses extensively co-opt their host gene expression machinery in order to quicky benefit from the host resources. The viral protein nsp1 plays a major role in this takeover as nsp1 is known to induce a widespread shutdown of the host gene expression, both at the RNA and the translational level. Previous work characterized the molecular basis for nsp1-mediated host shutdown. However, this was mostly conducted in the context of {beta}-coronaviruses and in particular SARS-CoV1, CoV2 and MERS due to the important public health burden that these viruses represent. Here instead, we explored the impact of nsp1 on the host using a comparative approach, defining the influence of 4 nsp1 protein from - and {beta}-coronaviruses. We delineated the impact of these 4 nsp1 on the host transcriptome and mapped their interactome. We revealed that host target range and interactomes vary widely among different nsp1, suggesting a viral-specific targeting. Understanding how these differences shape infection will be important to better inform antiviral drug development.

microbiology↗

bioRxiv2018

Identification of proteins involved in Trypanosoma brucei DNA replication fork dynamics using nascent DNA proteomics

DNA replication, transcription and chromatin remodeling are coordinated to ensure accurate duplication of genetic and epigenetic information. In regard to DNA replication, trypanosomatid parasites such as Trypanosoma brucei display unusual properties including significantly fewer origins of replication than model eukaryotes, a highly divergent Origin Replication Complex (ORC), and an apparent lack of several replication factor homologs. Although recent studies in T. brucei indicate functional links among DNA replication, transcription, and antigenic variation, the underlying mechanisms remain unknown. Here, we adapted an unbiased technology for the identification of replication fork proteins called iPOND (isolation of proteins on nascent DNA) to T. brucei, its first application to a parasite system. This led to the mass spectrometric identification of core replication machinery and of proteins associated with transcription, chromatin organization, and DNA repair that were enriched in the vicinity of an unperturbed active replication fork. Of a total of 410 enriched proteins, among which DNA polymerase and replication factor C were scoring in the top, around 25% of the proteins identified were of unknown function and, therefore, have the potential to be essential trypanosome-specific replication proteins. Initial characterization of a protein annotated as a Replication Factor C subunit (Tb927.10.7990), and a protein of unknown function (Tb927.3.5370) revealed that both proteins retain nuclear localization throughout the cell cycle. While Tb927.3.5370 appeared to be a dispensable gene, Tb927.10.7990 proved to be essential since its silencing caused a growth defect in procyclic cells, accumulation of zoids and impaired DNA replication. Future studies on the generated proteins list can contribute to the understanding of DNA replication dynamics in T. brucei and how replication is coordinated with other cellular processes to maintain genome integrity.

molecular biology↗