Biology subjects

Lescure, A.

Publications and source records attributed to Lescure, A..

8 recordsLinked to original sources

bioRxiv2026

Regulatory landscape of widespread stop codon readthrough in Drosophila

In stop codon readthrough (SCR), ribosomes continue to translate past the stop. While programmed SCR is rare in mammals, it appears remarkably widespread in insects, yet its regulation and biological significance remain poorly understood. Here, we systematically characterize SCR in Drosophila melanogaster by integrating ribosome profiling, comparative genomics, proteomics, and functional screening. We identify [~]1,400 SCR genes, reveal sequence features associated with programmed SCR, and distinguish constitutive and tissue-restricted modes. We identify conserved cis-elements sufficient to stimulate constitutive SCR and demonstrate that many remain functional in mammalian cells. Unexpectedly, the major distinction between insect and mammalian cells was not termination efficiency, but insect responsiveness to SCR-promoting regulatory elements. SCR was further associated with increased overall protein output, suggesting a function beyond proteome diversification. Our results establish SCR as a pervasive regulatory mechanism in Drosophila and provide a new framework for its study through the Drosophila Stop Codon Readthrough Atlas.

genomics↗

bioRxiv2021

Homosalate boosts the release of tumor-derived Extracellular Vesicles with anti-anoikis properties

Eukaryotic cells, including cancer cells, secrete highly heterogeneous populations of extracellular vesicles (EVs). EVs could have different subcellular origin, composition and functional properties, but tools to distinguish between EV subtypes are scarce. Here, we tagged CD63- or CD9-positive EVs secreted by triple negative breast cancer cells with Nanoluciferase enzyme, to set-up a miniaturized method to quantify secretion of these two EV subtypes directly in the supernatant of cells. We performed a cell-based high-content screening to identify clinically-approved drugs able to affect EV secretion. One of the identified hits is Homosalate, an anti-inflammatory drug found in sunscreens which robustly increased EVs release. Comparing EVs induced by Homosalate with those induced by Bafilomycin A1, we discovered that: 1) the two drugs act on EVs generated in distinct subcellular compartments and 2) EVs released upon treatment with Homosalate, but not with Bafilomycin A1, conferred anti-anoikis properties to another recipient tumor cell line. In conclusion, we identified a new drug modifying EV release and demonstrated that under influence of different drugs, triple negative breast cancer cells release EV subpopulations from different subcellular origins harboring distinct functional properties.

cell biology↗

bioRxiv2021

Discovery of genes that modulate flavivirus replication in an interferon-dependent manner

Establishment of the interferon (IFN)-mediated antiviral state provides a crucial initial line of defense against viral infection. Numerous genes that contribute to this antiviral state remain to be identified. Using a loss-of-function strategy, we screened an original library of 1156 siRNAs targeting 386 individual curated human genes in stimulated microglial cells infected with Zika virus (ZIKV), an emerging RNA virus that belongs to the flavivirus genus. The screen recovered twenty-one potential host proteins that modulate ZIKV replication in an IFN-dependent manner, including the previously known IFITM3 and LY6E. Further characterization contributed to delineate the spectrum of action of these genes towards other pathogenic RNA viruses, including Hepatitis C virus and SARS-CoV-2. Our data revealed that APOL3 acts as a proviral factor for ZIKV and several other related and unrelated RNA viruses. In addition, we showed that MTA2, a chromatin remodeling factor, possesses potent flavivirus-specific antiviral functions. Our work identified previously unrecognized genes that modulate the replication of RNA viruses in an IFN-dependent way, opening new perspectives to target weakness points in the life cycle of these viruses.

microbiology↗

bioRxiv2018

The role of Selenoprotein N in the differentiation of erythroid progenitors during stress erythropoiesis

Low serum Se is independently associated with anemia in elderly population, dialysis patients, sickle-cells patients, and hypothyroidism patients. Previous work from our laboratory showed that dietary Se deficiency in mice showed mild anemia indicating activation of stress-erythropoietic mechanisms. Unlike steady state erythropoiesis that is primarily responsible for homeostasis to produce new erythrocytes at a constant rate, stress erythropoiesis predominates when the bone marrow cannot generate sufficient erythrocytes. During such a process, short-term reconstituting hematopoietic stem cells (CD34+Kit+Sca1+Linneg) migrate to the spleen leading to the proliferation and differentiation of stress-erythroid progenitors (SEPs). These cells lead to stress burst forming unit-erythroid cells (BFU-E) followed by terminal differentiation to erythrocytes. Recent studies demonstrate deficits in selenoproteins block the expansion and development of stress BFU-E with defects in terminal differentiation. Analysis of selenoprotein expression showed that selenoprotein W (SelenoW) was highly expressed in developing SEPs. CRISPR-Cas9 knockout of SelenoW blocked the proliferation of immature SEPs in murine and human stress erythropoiesis cultures demonstrating a central role for SelenoW in stress erythropoiesis. Using the two-culture system to generate SEPs, selenoprotein N (SelenoN) expression increased as the progenitors transition from self-renewing \"stem cell like\" progenitors to form committed erythroid progenitors. SelenoN-/- mice showed significantly slower erythroid recovery following phenylhydrazine (PHZ)-induced acute hemolytic anemia. As in the muscle satellite cells where SelenoN regulates cellular Ca2+ signaling, SelenoN may also regulate Ca2+ signaling in SEPs to modulate pathways of differentiation. In summary, these data suggest that multiple selenoproteins, including SelenoN and SelenoW, coordinately regulate stress erythropoiesis.

developmental biology↗

bioRxiv2018

MYO1C facilitates arrival at the Golgi apparatus through stabilization of branched actin

We aim at the identification of myosin motor proteins that control trafficking at the Golgi apparatus. In addition to the known Golgi-associated myosins MYO6, MYO18A and MYH9 (myosin IIA), we identify MYO1C as a novel player at the Golgi. We demonstrate that depletion of MYO1C induces Golgi apparatus fragmentation and decompaction. MYO1C accumulates at dynamic structures around the Golgi apparatus that colocalize with Golgi-associated actin dots. Interestingly, MYO1C depletion leads to loss of cellular F-actin, and Golgi apparatus decompaction is also observed after the inhibition or loss of the Arp2/3 complex. We show that the functional consequences of MYO1C depletion is a delay in the arrival of incoming transport carriers, both from the anterograde and retrograde routes. We propose that MYO1C stabilizes branched actin at the Golgi apparatus that facilitates the arrival of incoming transport at the Golgi.

cell biology↗

bioRxiv2018

The small and large ribosomal subunits depend on each other for stability and accumulation

The 1:1 balance between the numbers of large and small ribosomal subunits can be disturbed by mutations that inhibit the assembly of one of the subunits. We have investigated if the cell has mechanisms to counteract an imbalance of subunits. We show that accumulation of 40S subunits stops after abrogating 60S assembly. In contrast, cessation of the 40S pathways does not prevent 60S accumulation, but does, however, lead to fragmentation of the 25S rRNA in 60S subunits. Even though 40S subunits do not accumulate in the absence of 60S assembly, 40S assembly continues, indicating that excess 40S is degraded after assembly. Thus, the cell expends substantial resources in a futile attempt to increase the number of functional 80S ribosomes. We propose that a mechanism for preventing the accumulation of 40S subunits in excess over 60S subunits may have evolved to prevent mRNAs from being tied up in 40S-mRNA translation initiation complexes that cannot be turned into productive translation complexes because of the deficit of 60S subunits.

molecular biology↗

bioRxiv2018

Dissecting transcriptomic signatures of neuronal differentiation and maturation using iPSCs

Human induced pluripotent stem cells (hiPSCs) are a powerful model of neural differentiation and maturation. We present a hiPSC transcriptomics resource on corticogenesis from 5 iPSC donor and 13 subclonal lines across nine time points over 5 broad conditions: self-renewal, early neuronal differentiation, neural precursor cells (NPCs), assembled rosettes, and differentiated neuronal cells that were validated using electrophysiology. We identified widespread changes in the expression of individual transcript features and their splice variants, gene networks, and global patterns of transcription. We next demonstrated that co-culturing human NPCs with rodent astrocytes resulted in mutually synergistic maturation, and that cell type-specific expression data can be extracted using only sequencing read alignments without potentially disruptive cell sorting. We lastly developed and validated a computational tool to estimate the relative neuronal maturity of iPSC-derived neuronal cultures and human brain tissue, which were maturationally heterogeneous but contained subsets of cells most akin to adult human neurons.

genomics↗

bioRxiv2018

Differential screening identifies molecules specifically inhibiting CCR5 transport to the cell surface and HIV infection

Proteins destined to the cell surface are conveyed through membrane-bound compartments using the secretory pathway. Multiple secretory routes exist in cells, which paves the way to the development of inhibitory molecules able to specifically perturb the transport of a chosen cargo. We used differential high-content screening of chemical libraries to identify molecules reducing the secretion of CCR5, the major co-receptor for HIV-1 entry. Three molecules strongly affected the anterograde transport of CCR5, without inhibiting the transport of the related G protein-coupled receptors CCR1 and CXCR4. These three molecules perturb the transport of endogenous CCR5 and decrease the entry of HIV in human primary target cells. Two molecules were found to share the same mode of action, inhibiting palmitoylation of CCR5. Our results demonstrate that secretory routes can be specifically targeted which allows to envisage novel strategies to provoke the intracellular retention or rerouting of secretory proteins involved in disease development.

cell biology↗