Vreux, L. | bioRxiv Science

bioRxiv2026

Identification of a key residue in the cellular transcription factor BCL11b important for its global acetylation and its nuclear localization

AO_SCPLOWBSTRACTC_SCPLOWThe cellular transcription factor BCL11b (B-cell CLL/lymphoma 11b) interacts with numerous cellular and viral factors to modulate gene expression positively or negatively. Post-translational modifications of BCL11b, such as SUMOylation and phosphorylation, have been documented to switch its transcriptional activity from a repressor to an activator state. In the present study, we investigated the acetylation of BCL11b and we identified the histone acetyltransferase p300 as able to acetylate BCL11b. Subsequently, we observed that the mutation of the lysine K686 residue of BCL11b (BCL11b K686R) influenced its global acetylation. Furthermore, the BCL11b K686R mutation also modulated the transcriptional regulation of BCL11b, including its activity in regulating the p21 and IL-2 promoters. This effect on transcriptional regulation was due to the importance of the lysine K686 residue for BCL11b nuclear localization. Our results underscore the critical role of the lysine K686 residue in BCL11b for its interaction with p300 and its nuclear localization, suggesting a possible function of p300 in the nuclear transport of BCL11b. Collectively, our findings contribute to a better understanding of BCL11b-mediated gene expression and of the interactions of BCL11b with cellular partners.

molecular biology↗

bioRxiv2024

Unbiased and comprehensive identification of viral encoded circular RNAs in a large range of viral species and families

Non-coding RNAs play a significant role in viral infection cycles, with recent attention focused on circular RNAs (circRNAs) originating from various viral families. Notably, these circRNAs have been associated with oncogenesis and alterations in viral fitness. However, identifying their expression has proven more challenging than initially anticipated due to unique viral characteristics. This challenge has the potential to impede progress in our understanding of viral circRNAs. Key hurdles in working with viral genomes include: (1) the presence of repetitive regions that can lead to misalignment of sequencing reads, and (2) unconventional splicing mechanisms that deviate from conserved eukaryotic patterns. To address these challenges, we developed vCircTrappist, a bioinformatic pipeline tailored to identify backsplicing events and pinpoint loci expressing circRNAs in RNA sequencing data. Applying this pipeline, we obtained novel insights from both new and existing datasets encompassing a range of animal and human pathogens belonging to Herpesviridae, Retroviridae, Adenoviridae and Orthomyxoviridae families. Subsequent RT-PCR and Sanger sequencings validated the accuracy of the developed bioinformatic tool for a selection of new candidate viral encoded circRNAs. These findings demonstrate that vCircTrappist is an open and unbiased approach for comprehensive identification of virus-derived circRNAs. Significance StatementCircular RNAs (circRNAs) were revealed to have prominent roles in cellular life in the past decade. They were more recently shown to be expressed by viruses, influencing their infectious cycles and host-pathogen relationship. In this context, viruses that were not previously associated with cellular splicing processes are shown to express circRNAs through unknown mechanisms. These non-canonical circRNAs were already shown to be important in the viral cycle and pathogenesis of the viruses they are encoded from. Here, we propose a bioinformatics pipeline that bypasses the limitations of the existing tools in the identification of viral circRNA. Using this pipeline, we discovered numerous candidates and invite the reader to start its own exploration in the realm of viral encoded circRNAs. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=72 SRC="FIGDIR/small/600382v1_ufig1.gif" ALT="Figure 1"> View larger version (16K): org.highwire.dtl.DTLVardef@1003330org.highwire.dtl.DTLVardef@20d366org.highwire.dtl.DTLVardef@116f38forg.highwire.dtl.DTLVardef@1d04a76_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioinformatics↗