Biology subjects

Antoniewski, C.

Publications and source records attributed to Antoniewski, C..

14 recordsLinked to original sources

bioRxiv2025

FGF overactivation underlies reduced neurogenesis in cerebellar organoid models of neurodevelopmental ciliopathy

The primary cilium acts as a specialized signaling compartment that coordinates multiple developmental pathways, yet its role in regulating signaling activity during human brain development remains poorly understood. Biallelic mutations in ciliary genes cause neurodevelopmental ciliopathies such as Joubert syndrome, which are characterized by cerebellar hypoplasia and dysplasia. Here, we generated human cerebellar organoids carrying null or patient-derived mutations in RPGRIP1L, a ciliary transition zone gene associated with Joubert Syndrome, to investigate how ciliary dysfunction alters human cerebellar neurogenesis. While control organoids robustly express markers of cerebellar glutamatergic and GABAergic lineages including Purkinje cells, RPGRIP1L-deficient organoids display a consistent and severe reduction in Purkinje cell markers, accompanied by impaired neurogenesis and increased progenitor proliferation. These defects coincide with prolonged overactivation of the FGF/MAPK signaling pathway. We further show that the MAPK effector pMEK1/2 localizes at the base of primary cilia, where its levels are significantly increased in RPGRIP1L-deficient cerebellar progenitors. Pharmacological inhibition of FGF receptors reduces pMEK1/2 activation at cilia base and rescues both the proliferation-neurogenesis imbalance and Purkinje lineage defects, without restoring the underlying ciliary abnormalities. Together, our findings identify the primary cilium as a compartment that refines FGF/MAPK signaling in human cerebellar progenitors, and support a model in which RPGRIP1L restrains FGF pathway activity to promote neurogenesis. These results provide a mechanism linking ciliary dysfunction to altered cerebellar development and provide new insight into the developmental origin of cerebellar impairment in neurodevelopmental ciliopathies

developmental biology↗

bioRxiv2024

A unique malignant cell type per patient tumor is encoded in each cancer cell transcriptome.

Deciphering shared features between patients through unsupervised analyses of tumor single-cell transcriptomes is hindered by the predominant clustering of malignant cells based on the patients tumor of origin. In contrast, cancer-associated non-malignant cells within tumors cluster according to their somatic cell type (e.g. macrophage, fibroblast, astrocyte), regardless of the individual patient. We investigated the origin of this contrasting clustering behavior using computational analyses and novel data sampling techniques across 160 tumors representing 9 distinct cancer types. This led to the unexpected disclosing of tumor-specific malignant cell types. We demonstrate that tumor-driven malignant cell clustering is independent from technical or computational biases, nor is it reducible to defined gene sets with tumor-specific expression across all examined cancers. On the opposite, we unveil redundant information dispersed across the transcriptome that encodes a unique identity shared by the malignant cells within each tumor. Additionally, we found a similar genomic encoding for the identity of normal cell types. Finally, we demonstrate that malignant cell identities are maintained across space and over time, as are the identities of normal somatic cells types. These findings suggest the establishment of a distinct type of malignant cells within each tumor, robustly and diffusively encoded across the entire transcribed genome.

cancer biology↗

bioRxiv2024

Transcriptomic analysis of meiotic genes during the mitosis-to-meiosis transition in Drosophila females

Germline cells produce gametes, which are specialized cells essential for sexual reproduction. Germline cells first amplify through several rounds of mitosis before switching to the meiotic program, which requires specific sets of proteins for DNA recombination, chromosome pairing and segregation. Surprisingly, we previously found that some proteins of the synaptonemal complex, a prophase I meiotic structure, are already expressed and required in the mitotic region of Drosophila females. Here, to assess if additional meiotic genes were expressed earlier than expected, we isolated mitotic and meiotic cell populations to compare their RNA content. Our transcriptomic analysis reveals that all known meiosis I genes are already expressed in the mitotic region, however, only some of them are translated. As a case study, we focused on mei-W68, the Drosophila homologue of Spo11, to assess its expression at both the mRNA and protein levels, and used different mutant alleles to assay for a pre-meiotic function. We could not detect any functional role for Mei-W68 during homologous chromosome pairing in dividing germ cells. Our study paves the way for further functional analysis of meiotic genes expressed in the mitotic region. Article SummaryGermline cells, crucial for sexual reproduction, were thought to switch to meiosis only after several rounds of mitosis. Surprisingly, a few meiotic proteins were found active in the mitotic phase of female flies. Here, we discovered that all known meiosis genes were expressed during mitosis, but only some produced proteins. This study suggests that genes related to reproduction are active earlier than expected, prompting further exploration into their functions during early cell division.

developmental biology↗

bioRxiv2023

High CD44 expression identifies rare chemoresistant leukemic cells endowed with enhanced E-Selectin binding in T-ALL

T-cell acute lymphoblastic leukemia (T-ALL) is a hematopoietic malignancy characterized by an increased proliferation and incomplete maturation of T-cell progenitors. Despite therapeutic improvements, relapses are often of bad prognosis. Therapeutic vulnerabilities and chemoresistance mechanisms arising from cell plasticity induced by the bone marrow (BM) microenvironment remain an important field of investigation. Employing single cell RNA sequencing (scRNAseq) of human T-ALL cells recovered from adipocyte-rich and -poor BM, a distinct leukemic stem cell (LSC) population defined by quiescence and elevated CD44 level (Ki67neg/lowCD44high) expression is identified in both territories. In vivo chemotherapy demonstrated that the LSC population evades drug treatment. Patient sample analyses confirmed the presence of Ki67neg/lowCD44high LSC both at diagnosis and relapse that displayed a specific transcriptomic signature. Interestingly, the intense expression of CD44 in T-ALL Ki67neg/lowLSC was associated with E-selectin binding. Importantly, when 39 human T-ALL samples were analyzed, the E-selectin binding ability was found significantly higher in Relapse/Refractory compared to drug-sensitive patients. These findings characterize a T-ALL LSC population with chemoresistant properties and shade light on new strategies for prognostic stratification while opening avenues for novel therapeutic options.

cancer biology↗

bioRxiv2023

Switching of RNA splicing regulators in immature neuroblasts: a key step in adult neurogenesis

The lateral wall of the subventricular zone harbors neural stem cells (NSC, B cells) which generate proliferating transient-amplifying progenitors (TAP, C cells) that ultimately give rise to neuroblasts (NB, A cells). Molecular profiling at the single cell level struggles to distinguish these different cell types. Here, we combined transcriptome analyses of FACS-sorted cells and single-cell RNAseq to demonstrate the existence of an abundant, clonogenic and multipotent population of immature neuroblasts (iNB cells) at the transition between TAP and migrating NB (mNB). iNB are reversibly engaged in neuronal differentiation. Indeed, they keep molecular features of both undifferentiated progenitors, plasticity and unexpected regenerative properties. Strikingly, they undergo important progressive molecular switches, including changes in the expression of splicing regulators leading to their differentiation in mNB subdividing them into 2 subtypes, iNB1 and iNB2. Due to their plastic properties, iNB could represent a new target for regenerative therapy of brain damage.

genomics↗

bioRxiv2022

Smurfness-based two-phase model of ageing helps deconvolve the ageing transcriptional signature

Ageing is characterised at the molecular level by six transcriptional hallmarks of ageing, that are commonly described as progressively affected as time passes. By contrast, the Smurf assay separates high-and-constant-mortality risk individuals from healthy, zero-mortality risk individuals, based on increased intestinal permeability. Performing whole body total RNA sequencing, we found that Smurfness distinguishes transcriptional changes associated with chronological age from those associated with biological age. We show that transcriptional heterogeneity increases with chronological age in non-Smurf individuals preceding the other five hallmarks of ageing, that are specifically associated with the Smurf state. Using this approach, we also devise targeted pro-longevity genetic interventions delaying entry in the Smurf state. We anticipate that increased attention to the evolutionary conserved Smurf phenotype will bring about significant advances in our understanding of the mechanisms of ageing. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=150 HEIGHT=200 SRC="FIGDIR/small/517330v5_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@37b39org.highwire.dtl.DTLVardef@8ef8f0org.highwire.dtl.DTLVardef@797299org.highwire.dtl.DTLVardef@1529b0d_HPS_FORMAT_FIGEXP M_FIG The two-phase model of ageing allows to study separately the effect of chronological and physiological age. (A) Classic approaches for studying ageing tend to consider it as a black box affecting all individuals progressively from birth to death. Instead, the Smurf phenotype shows that life can be divided into two consecutive phases separated by an abrupt transition. (B) All individuals undergo this transition at a different moment in their life, prior to death. This allows us to switch from population based approaches, comparing bulks of age-matched individuals through time, to individuals-centred approaches relying on direct access to their transition status. (C) Such paradigm shift shows that hallmarks of ageing long thought to progressively change with age are actually mostly affected in a growing proportion of Smurfs, allowing for the identification of the chain of events accompanying ageing and death from natural causes. (D) By studying the behaviour of the ageing transcriptome as a function of chronological age and Smurfness separately, we demonstrate that the progressively changing transcriptional ageing signature, as described in Frenk & Houseley (2018), is in fact the convolution changes accompanying chronological age signature (increased transcriptional noise) and changes associated with Smurfness (or biological age) signature (increased stress response and inflammation, decreased expression of ribosomal and mitochondrial genes). We also identified a hallmark partially associated with only old Smurfs (ATH5), suggesting that chronological age can affect, late in life, the Smurf response. C_FIG

systems biology↗

bioRxiv2022

Cellular senescence in malignant cells promotes tumor progression in mouse and patient Glioblastoma

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults, yet it remains refractory to systemic therapy. Elimination of senescent cells has emerged as a promising new treatment approach against cancer. Here, we investigated the contribution of senescent cells to GBM progression. Senescent cells were identified in patient and mouse GBMs. Partial removal of p16Ink4a-expressing malignant senescent cells, which make up less than 7 % of the tumor, modified the tumor ecosystem and improved the survival of GBM-bearing mice. By combining single cell and bulk RNA sequencing, immunohistochemistry and genetic knockdowns, we identified the NRF2 transcription factor as a determinant of the senescent phenotype. Remarkably, our mouse senescent transcriptional signature and underlying mechanisms of senescence are conserved in patient GBMs, in whom higher senescence scores correlate with shorter survival times. These findings suggest that senolytic drug therapy may be a beneficial adjuvant therapy for patients with GBM.

cancer biology↗

bioRxiv2022

Human glioblastoma cell motility depends on the activity of the cysteine metabolism enzyme 3-Mercaptopyruvate sulfurtransferase

Cancer cells in similar functional states are found in all glioblastoma, despite the genomic heterogeneity observed between and within these brain tumors. Metabolism being downstream of all signaling pathways regulating cell behaviors, we looked for metabolic weaknesses in link with motility, a key functional state for glioblastoma aggressiveness. A signature-driven data reduction approach highlighted motile cells present in thirty tumors from four independent single-cell transcriptomic datasets. Analyses integrating trajectory modeling disclosed, as characteristic of motile cells, enhanced oxidative stress coupled with mobilization of the cysteine metabolism enzyme 3-Mercaptopyruvate sulfurtransferase (MPST). The soundness of this prediction was verified using migration and invasion assays with patient-derived cells and tissue organoids. Pharmacological and genetic manipulations showed that enhanced ROS production and MPST activity are required for the cells motility. Biochemical assays indicated that MPST acts by protecting protein cysteine residues from dismal hyperoxidation. In vivo, MPST knockdown translated in reduced tumor burden, and a robust increase in mice survival. These results show that enhanced oxidative stress coupled with MPST mobilization plays a key role in glioblastoma cell motility.

cancer biology↗

bioRxiv2020

A single-cell RNA-seq Training and Analysis Suite using the Galaxy Framework

BackgroundThe vast ecosystem of single-cell RNA-seq tools has until recently been plagued by an excess of diverging analysis strategies, inconsistent file formats, and compatibility issues between different software suites. The uptake of 10x Genomics datasets has begun to calm this diversity, and the bioinformatics community leans once more towards the large computing requirements and the statistically-driven methods needed to process and understand these ever-growing datasets. ResultsHere we outline several Galaxy workflows and learning resources for scRNA-seq, with the aim of providing a comprehensive analysis environment paired with a thorough user learning experience that bridges the knowledge gap between the computational methods and the underlying cell biology. The Galaxy reproducible bioinformatics framework provides tools, workflows and trainings that not only enable users to perform one-click 10x preprocessing, but also empowers them to demultiplex raw sequencing from custom tagged and full-length sequencing protocols. The downstream analysis supports a wide range of high-quality interoperable suites separated into common stages of analysis: inspection, filtering, normalization, confounder removal and clustering. The teaching resources cover an assortment of different concepts from computer science to cell biology. Access to all resources is provided at the singlecell.usegalaxy.eu portal. ConclusionsThe reproducible and training-oriented Galaxy framework provides a sustainable HPC environment for users to run flexible analyses on both 10x and alternative platforms. The tutorials from the Galaxy Training Network along with the frequent training workshops hosted by the Galaxy Community provide a means for users to learn, publish and teach scRNA-seq analysis. Key PointsO_LISingle-cell RNA-seq has stabilised towards 10x Genomics datasets. C_LIO_LIGalaxy provides rich and reproducible scRNA-seq workflows with a wide range of robust tools. C_LIO_LIThe Galaxy Training Network provides tutorials for the processing of both 10x and non-10x datasets. C_LI

bioinformatics↗

bioRxiv2019

tRNA fragments (tRFs) populations analysis in mutants affecting tRNAs processing and tRNA methylation

tRNA fragments (tRFs) are a class of small non-coding RNAs (sncRNAs) derived from tRNAs. tRFs are highly abundant in many cell types including stem cells and cancer cells, and are found in all domains of life. Beyond translation control, tRFs have several functions ranging from transposon silencing to cell proliferation control. However, the analysis of tRFs presents specific challenges and their biogenesis is not well understood. They are very heterogeneous and highly modified by numerous post-transcriptional modifications. Here we describe a bioinformatic pipeline to study tRFs populations and shed light onto tRNA fragments biogenesis. Indeed, we used small RNAs Illumina sequencing datasets extracted from wild type and mutant Drosophila ovaries affecting two different highly conserved steps of tRNA biogenesis: 5pre-tRNA processing (RNase-P subunit Rpp30) and tRNA 2-O-methylation (CG7009 and CG5220). Using our pipeline, we show how defects in tRNA biogenesis affect nuclear and mitochondrial tRFs populations and other small non-coding RNAs biogenesis, such as small nucleolar RNAs (snoRNAs). This tRF analysis workflow will advance the current understanding of tRFs biogenesis, which is crucial to better comprehend tRFs roles and their implication in human pathology.

bioinformatics↗

bioRxiv2019

Capture at the single cell level of metabolic modules distinguishing aggressive and indolent glioblastoma cells

Glioblastoma cell ability to adapt their functioning to microenvironment changes is a source of the extensive intra-tumor heterogeneity characteristic of this devastating malignant brain tumor. A systemic view of the metabolic pathways underlying glioblastoma cell functioning states is lacking. We analyzed public single cell RNA-sequencing data from glioblastoma surgical resections, which offer the closest available view of tumor cell heterogeneity as encountered at the time of patients diagnosis. Unsupervised analyses revealed that information dispersed throughout the cell transcript repertoires encoded the identity of each tumor and masked information related to cell functioning states. Data reduction based on an experimentally-defined signature of transcription factors overcame this hurdle. It allowed cell grouping according to their tumorigenic potential, regardless of their tumor of origin. The approach relevance was validated using an independent dataset of glioblastoma tissue transcriptomes, patient-derived cell lines and orthotopic xenografts. Overexpression of genes coding for amino acid and lipid metabolism enzymes involved in anti-oxidative, energetic and cell membrane processes characterized cells with high tumorigenic potential. Modeling of their expression network highlighted the very long chain polyunsaturated fatty acid synthesis pathway at the core of the network. Expression of its most downstream enzymatic component, ELOVL2, was associated with worsened patient survival, and required for cell tumorigenic properties in vivo. Our results demonstrate the power of signature-driven analyses of single cell transcriptomes to obtain an integrated view of metabolic pathways at play within the heterogeneous cell landscape of patient tumors.

cancer biology↗

bioRxiv2019

tRNA 2-O-methylation modulates small RNA silencing and life span in Drosophila.

2-O-methylation (Nm) represents one of the most common RNA modifications. Nm affects RNA structure and function with crucial roles in various RNA-mediated processes ranging from RNA silencing, translation, self versus non-self recognition to viral defense mechanisms. Here, we identify two novel Nm methyltransferases (Nm-MTases) in Drosophila melanogaster (CG7009 and CG5220) as functional orthologs of yeast TRM7 and human FTSJ1, respectively. Genetic knockout studies together with MALDI-TOF mass spectrometry and RiboMethSeq mapping revealed that CG7009 is responsible for methylating the wobble position in tRNAPhe, tRNATrp and tRNALeu, while subsequently, CG5220 methylates position C32 in the same tRNAs and targets also additional tRNAs. CG7009 or CG5220 mutant animals were viable and fertile but exhibited various phenotypes such as life span reduction, small RNA pathways dysfunction and increased sensitivity to RNA virus infections. Our results provide the first detailed characterization of two TRM7 family members in Drosophila and uncover a molecular link between enzymes catalysing Nm at specific tRNAs and small RNA-induced gene silencing pathways.

molecular biology↗

bioRxiv2018

GC content shapes mRNA decay and storage in human cells

Control of protein expression results from the fine tuning of mRNA synthesis, decay and translation. These processes, which are controlled by a large number of RNA-binding proteins and by localization in RNP granules such as P-bodies, appear often intimately linked although the rules of this interplay are not well understood. In this study, we combined our recent P-body transcriptome with various transcriptomes obtained following silencing of broadly acting mRNA decay and repression factors. This analysis revealed the central role of GC content in mRNA fate, in terms of P-body localization, mRNA translation and mRNA decay. It also rationalized why PBs mRNAs have a strikingly low protein yield. We report too the existence of distinct mRNA decay pathways with preference for AU-rich or GC-rich transcripts. Compared to this impact of the GC content, sequence-specific RBPs and miRNAs appeared to have only modest additional effects on their bulk targets. Altogether, these results lead to an integrated view of post-transcriptional control in human cells where most regulation at the level of translation is dedicated to AU-rich mRNAs, which have a limiting protein yield, whereas regulation at the level of 5 decay applies to GC-rich mRNAs, whose translation is optimal.

molecular biology↗

bioRxiv2018

Dual-layer transposon repression in heads of Drosophila melanogaster

piRNA-mediated repression of transposable elements (TE) in the germline limits the accumulation of heritable mutations caused by their transposition in the genome. It is not clear whether the piRNA pathway plays a functional role in adult, non-gonadal tissues in Drosophila melanogaster. To address this question, we first analyzed the small RNA content of adult Drosophila melanogaster heads. We found that varying amount of piRNA-sized, ping-pong positive molecules in heads correlates with contamination by gonadal tissue during RNA extraction, suggesting that most of piRNAs detected in head sequencing libraries originate from gonads. We next sequenced the heads of wild type and piwi mutants to address whether piwi loss of function would affect the low amount of piRNA-sized, ping-pong negative molecules that are still detected in heads hand-checked to avoid gonadal contamination. We find that loss of piwi does not affect significantly these 24-28 RNA molecules. Instead, we observe increased siRNA levels against the majority of Drosophila transposable element families. To determine the effect of this siRNA level change on transposon expression, we sequenced the transcriptome of wild type, piwi, dicer-2 and piwi, dicer-2 double-mutant fly heads. We find that RNA expression levels of the majority of TE families in piwi or dicer-2 mutants remain unchanged and that TE transcript abundance increases significantly only in piwi, dicer-2 double-mutants. These results lead us to suggest a dual-layer model for TE repression in adult somatic tissues. Piwi-mediated transcriptional gene silencing (TGS) established during embryogenesis constitutes the first layer of TE repression whereas Dicer-2-dependent siRNA-mediated post-transcriptional gene silencing (PTGS) provide a backup mechanism to repress TEs that escape silencing by piwi-mediated TGS.

genetics↗