Biology subjects

Marcel, V.

Publications and source records attributed to Marcel, V..

8 recordsLinked to original sources

bioRxiv2025

Translatome and translation dynamics analysis of a RiboCancer cell line panel reveals that leukemia-associated Rps15 mutations rewire translation through codon-specific tRNA accommodation defects.

Deletions and point mutations targeting ribosomal proteins (RPs) have been identified in cancer. Yet, their role in translational dysregulation remains poorly understood. We performed an integrated genome-wide translatome analysis (proteome, Ribo-seq and total RNA-seq) as well as RiboMethSeq on an isogenic cell line library modeling the most recurrent RP defects in cancer (Rpl5+/-, Rpl11+/-, Rpl22+/-, Rpl22-/-, Rpl10 R98S, Rps15 P131S and Rps15 H137Y). RP knock-out had minimal effects on translation, whereas RP point mutations induced a significant number of translation efficiency changes, affecting up to 10% of expressed genes in Rps15 mutants associated with Chronic Lymphocytic Leukemia (CLL). Cryo-electron microscopy and biochemical analyses revealed that the Rps15 mutations destabilize the C-terminal Rps15 domain, affecting the translation elongation cycle dynamics, and deregulating accommodation of aminoacylated tRNAs at the ribosomal A-site. Using Ribo-seq and translation reporter assays, we show that this accommodation defect shows codon specificity, explaining the reduced translation efficiency of genes enriched for these codons in Rps15 mutant cells, such as histones. Notably, genes with reduced translation efficiency in Rps15 mutated cells were enriched for transcriptional regulators such as transcription factor Runx3, resulting in downregulation of Runx3 target genes involved in immune regulation. Altogether, this study provides a comparative map of the translational rewiring driven by the most frequent somatic RP mutations. We provide unprecedented mechanistic insights in the translation defects induced by CLL-associated Rps15 mutations, and reveal an unappreciated cross-talk between translational and transcriptional dysregulation in these RP mutant cells. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=102 SRC="FIGDIR/small/687986v1_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@cd2846org.highwire.dtl.DTLVardef@10f3c49org.highwire.dtl.DTLVardef@13f1595org.highwire.dtl.DTLVardef@a212df_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2025

SnoBIRD: A tool to identify C/D box snoRNAs and refine their annotation across all eukaryotes

Small nucleolar RNAs (snoRNAs), a group of noncoding RNAs present amongst all eukaryotes, are most extensively characterized for their regulation of ribosome biogenesis and splicing. Despite their central roles, current snoRNA annotations remain incomplete. Several eukaryote genome annotations contain few or no snoRNAs, and none distinguish expressed snoRNAs from their pseudogenes--a recently characterized snoRNA subclass with distinct features and expression levels. To address this, we developed SnoBIRD, a BERT-based C/D box snoRNA predictor trained on snoRNAs spanning all eukaryote kingdoms. We show that SnoBIRD outperforms existing tools and is the only predictor capable of identifying snoRNA pseudogenes using biologically relevant signal. Applied on the fission yeast and human genomes, we demonstrate that only SnoBIRD scales well with genome size in terms of runtime, and we identify and experimentally validate several new SnoBIRD-predicted C/D box snoRNAs. By running SnoBIRD on multiple eukaryote genomes, we identify hundreds of novel snoRNA candidates and highlight SnoBIRDs usefulness to determine the evolutionary paths of snoRNAs distributed across different species. Overall, SnoBIRD represents a user-friendly and efficient tool for reliably predicting C/D box snoRNAs and their pseudogenes across any eukaryote genome. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/646650v1_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@99b390org.highwire.dtl.DTLVardef@dbe375org.highwire.dtl.DTLVardef@32358aorg.highwire.dtl.DTLVardef@58fb3a_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioinformatics↗

bioRxiv2025

A TranSNP in the DDIT4 mRNA can impact its translation efficiency and modulate p53-dependent responses in cancer cells

Relatively few studies have examined the link between SNPs and mRNA translation, despite the established importance of translational regulation in shaping cell phenotypes. We developed a pipeline analyzing the allelic imbalance in total and polysome-bound mRNAs from paired RNA-seq data of HCT116 cells and identified 40 candidate tranSNPs, i.e. SNPs associated with allele-specific translation. Among them, the SNP rs1053639 (T/A) on DNA damage-inducible transcript 4 (DDIT4) 3UTR was identified, with the reference T allele showing a higher polysome association. rs1053639 TT clones generated by genome editing exhibited significantly higher DDIT4 protein levels than AA ones. The difference in DDIT4 proteins was even greater when cells were treated with Thapsigargin or Nutlin, two perturbations that induce DDIT4 transcription. The RNA-binding protein RBMX influenced these allele-dependent differences in DDIT4 protein expression, as shown by RNA-EMSA, RIP, and smiFISH assays. RBMX depletion reduced DDIT4 protein in TT clones to the AA levels. Functionally, TT clones more effectively repressed mTORC1 under ER stress, while AA clones outcompeted TT clones in vitro or when injected in zebrafish embryos. RBMX depletion increased the fitness of TT cells in co-culture experiments. The rs1053639 AA genotype, under a recessive model, correlates with poor prognosis in TCGA cancer data. Key points- Translatome analysis in HCT116 cells revealed allele-specific mRNA translation for 40 SNPs - rs1053639 (T/A) in DDIT4 3UTR showed allelic differences in mRNA localization & protein expression - AA cells showed weaker mTOR inhibition & higher proliferation; AA individuals had poorer prognosis

molecular biology↗

bioRxiv2025

Ribosome biogenesis is a therapeutic vulnerability in paediatric neuroblastoma

BackgroundNeuroblastoma is a heterogeneous malignant paediatric tumor with prognosis depending on patient age and disease stage. Current treatment strategies rely on four key diagnostic criteria: age, histological stage, MYCN gene status, and genomic profile. It has been reported that MYC oncogenic activity depends on ribosome biogenesis, whose hyperactivation in cancer cells supports their high proliferative capacity, and thus represent a potential therapeutic target. Methodswe utilized the well-established IMR-32 cell line along with a panel of patient-derived neuroblastoma cell lines with varying MYCN status, which we previously established. Additionally, we generated an IMR-32 cell line expressing an shRNA targeting the ribosome biogenesis factor fibrillarin (FBL). Cell growth, apoptosis markers, and cell cycle regulators were analyzed. Expression of ribosome biogenesis factors was assessed using publicly available datasets and RT-qPCR data from an in-house neuroblastoma cohort. ResultsWe explored whether ribosome biogenesis represents a vulnerability in neuroblastoma. Our findings demonstrate that inhibition of RNA polymerase I using CX-5461 and BMH-21 suppressed cell proliferation at nanomolar concentrations and induced ribosomal stress, leading to activation of apoptosis and the p21 pathway. Furthermore, we identified FBL as a marker of poor prognosis in neuroblastoma. Consistently, FBL knockdown reduced neuroblastoma cell proliferation, supporting its potential as a therapeutic target. ConclusionOur study reinforces the therapeutic potential of ribosome biogenesis inhibition in neuroblastoma and expands the list of potential targets to include rRNA maturation factors. These findings highlight the promise of targeting ribosome biogenesis as a novel approach for neuroblastoma treatment.

cancer biology↗

bioRxiv2025

Fibrillarin-mediated ribosomal RNA maturation is a novel therapeutic vulnerability in triple-negative breast cancer

Triple-negative breast cancer (TNBC) remains one of the most challenging breast cancer subtypes to treat due to the lack of effective therapeutic options. Ribosome biogenesis has recently emerged as a promising therapeutic target across various cancers. Despite the current targeting of ribosome biogenesis through RNA polymerase I (RNA Pol I) inhibition, we speculated that other factors essential for ribosome assembly, such as rRNA maturation factors, may also represent therapeutic targets in TNBC. Here, we demonstrate that ribosome biogenesis-related genes are notably overexpressed in TNBC compared to other breast cancer subtypes, highlighting its critical role in TNBC progression. Accordingly, we show that RNA Pol I inhibition exerts potent anti-proliferative effects in pre-clinical models of TNBC, both in vitro and in vivo. However, the DNA-damaging activity of RNA Pol I inhibitors raises safety concerns, highlighting the need for alternative strategies to inhibit ribosome biogenesis. To this end, we show that targeting a downstream rRNA maturation step, specifically pre-rRNA cleavage, by inhibiting the maturation factor Fibrillarin, also inhibits tumor growth in TNBC models. Notably, ribosome biogenesis inhibition, through either RNA Pol I or Fibrillarin targeting, induces cell cycle arrest without triggering significant cell death. These findings establish ribosome biogenesis as a therapeutic vulnerability in TNBC and identify rRNA maturation, and Fibrillarin in particular, as novel targets for potential therapeutic intervention. SignificanceTargeting ribosome biogenesis, through inhibition of either rRNA synthesis or maturation, induces anti-tumoral effects in TNBC, representing a novel therapeutic vulnerability with potential to improve patient outcomes.

cancer biology↗

bioRxiv2024

Targeting a shared neoepitope derived from non-canonical translation of c-MYC oncogene in cancer cells

Cancer cells rely on alternative modes of translation for protein synthesis, promoting internal ribosome entry site (IRES)-dependent translation of mRNA encoding pro-oncogenic factors. Furthermore, ribosomes translate mRNA with lower fidelity in tumor cells. We proposed that these translational modifications in cancer produce shared tumor-specific epitopes derived from IRES-containing oncogenes. To identify such neoepitopes, we developed an in silico-based method that we applied to c-MYC. We showed that the non-canonical translation of c-MYC mRNA in cancer cells, involving a (+1) ribosomal frameshift, generates a shared neoepitope which induces high-avidity T cells able to kill tumor cells in vitro and in vivo while sparing normal cells. Our data provide preclinical rationale for developing immunotherapies targeting this c-MYC-derived neoepitope and validate a new type of shared translation-associated neoantigens.

immunology↗

bioRxiv2024

SURF2 is a MDM2 antagonist in triggering the nucleolar stress response

Cancer cells are addicted to strong ribosome production to sustain their proliferation rate. Many chemotherapies impede ribosome production which is perceived by cells as "nucleolar stress" (NS), triggering p53-dependent and independent response pathways leading to cell cycle arrest and/or apoptosis. The 5S RNP particle, a sub-ribosomal particle, is instrumental to NS response. Upon ribosome assembly defects, the 5S RNP accumulate as free form. This free form is able to sequester and inhibit MDM2, thus promoting p53 stabilization. To investigate how cancer cells can resist to NS, we purified free-5S RNP and uncovered a new interaction partner, SURF2. Functional characterization of SURF2 shows that its depletion increases cellular sensitivity to NS, while its overexpression promotes their resistance to it. Consistently, SURF2 expression level negatively correlates with the overall survival in adrenocortical and head and neck squamous cell carcinomas. Our data demonstrate that SURF2 buffers free-5S RNP particles, and can modulate their activity. SURF2 regulates NS responses, and is a key player in both ribosomopathies and oncogenic mechanisms.

cell biology↗

bioRxiv2020

Alteration of ribosome function upon 5-fluorouracil treatment favours cancer cell drug-tolerance

Partial response to chemotherapy leads to disease resurgence. Upon treatment, a subpopulation of cancer cells, called drug-tolerant persistent cells, display a transitory drug tolerance that lead to treatment resistance 1,2. Though drug-tolerance mechanisms remain poorly known, they have been linked to non-genomic processes, including epigenetics, stemness and dormancy 2-4. 5-fluorouracil (5-FU), the most widely used chemotherapy in cancer treatment, is associated with resistance. While prescribed as an inhibitor of DNA replication, 5-FU alters all RNA pathways 5-9. Here, we show that 5-FU treatment leads to the unexpected production of fluorinated ribosomes, exhibiting altered mRNA translation. 5-FU is incorporated into ribosomal RNAs of mature ribosomes in cancer cell lines, colorectal xenografts and human tumours. Fluorinated ribosomes appear to be functional, yet, they display a selective translational activity towards mRNAs according to the nature of their 5-untranslated region. As a result, we found that sustained translation of IGF-1R mRNA, which codes for one of the most potent cell survival effectors, promoted the survival of 5-FU-treated colorectal cancer cells. Altogether, our results demonstrate that "man-made" fluorinated ribosomes favour the drug-tolerant cellular phenotype by promoting translation of survival genes. This could be exploited for developing novel combined therapies. By unraveling translation regulation as a novel gene expression mechanism helping cells to survive a drug-challenge, our study extends the spectrum of molecular mechanisms driving drug-tolerance.

cancer biology↗