Biology subjects

Vincent, J.-P.

Publications and source records attributed to Vincent, J.-P..

10 recordsLinked to original sources

bioRxiv2026

Xrp1 integrates cellular stress through different control modes in Drosophila

Cells and tissues have the ability to respond to different stresses and maintain their homeostasis. The b-Zip transcription factor Xrp1 was found to play a pivotal role in this context in Drosophila. Xrp1 is required for the response to irradiation, in genetic conditions of ribosomal protein (Rp) deficiency leading to cell competition, and more generally in mediating the Integrated Stress Response (ISR). However, how these diverse stresses converge to and activate Xrp1 is still unclear. Our results demonstrate the existence of three separate mechanisms of Xrp1 induction. In response to Rp stress, a short isoform of Xrp1 is produced and requires the function of the ribosomal protein RpS12. In response to irradiation, a specific mRNA isoform is transcriptionally induced, which encodes the Xrp1-short protein isoform, in a p53-dependent manner. In response to the ISR, the long isoform of Xrp1 is translated by the derepression of a uORF present on the Xrp1 5'UTR, a mechanism that requires eIF2 phosphorylation, RpS12, and a transcriptional induction by ATF4. Therefore, our work provides a comprehensive understanding of the role of Xrp1 in different situations of cellular stress, illustrating the complex level of integration of the mechanisms controlling this central gene.

developmental biology↗

bioRxiv2026

An in vivo chemical genetic approach for targeted glycoproteome analysis in Drosophila melanogaster

Glycans impact every aspect of physiology. Despite the rapid increase in relevance and translational potential, there remains a lack of tools for studying glycosylation in vivo. Here, we present FlyMOE, a chemical-genetic platform for targeted glycoprotein profiling in Drosophila melanogaster. Transgenic flies are equipped with biosynthetic capabilities to install bioorthogonally-tagged monosaccharides into the cellular glycoproteome. The genetic tractability of Drosophila allows for versatile application based on developmental stages, genetic drivers and glycosyltransferase enzymes. We employ FlyMOE to create an overview of the glycoproteome of Drosophila tissues and embryos based on mass spectrometry glycoproteomics, and investigate the substrates of individual members of the PGANT glycosyltransferase family in vivo. FlyMOE will allow the detailed investigation of the glycoproteome in Drosophila and similarly genetically modifiable in vivo model systems.

bioengineering↗

bioRxiv2026

Membrane lipid composition and endocytosis modulate Wingless release from secreting cells

Wnts are secreted signalling molecules that regulate development and adult homeostasis. Most Wnts carry a lipid moiety that must be shielded from the aqueous environment. In the secretory pathway, this is achieved by a hydrophobic tunnel in Wntless, a multipass transmembrane protein. However, the Wnt lipid moiety must be released from Wntless before Wnts can engage with Frizzled receptors on receiving cells. Here we address the cell biological basis of Wnt-Wntless dissociation, using as a model the secretion of Drosophila Wingless in wing primordia. Super-resolution microscopy shows that Wingless first reaches the apical surface before being re-internalized to reach, without Wntless, specialized Rab7/Rab4-positive endosomes. From there Wingless traffics to the basolateral membrane where it can engage with glypicans to form a basolateral gradient. Acute inhibition of endocytosis, either with a temperature-sensitive dynamin mutant or a novel optogenetic means of inhibiting clathrin, leads to apical Wingless release in abnormal punctae devoid of Wntless, suggesting that Wingless-Wntless dissociation commences at the apical surface, perhaps because of a distinct lipid composition there. Indeed, similar looking punctae are produced upon genetic abrogation of the ceramide synthase Schlank, specifically in Wingless-producing cells. These punctae resemble insoluble aggregates that form in vitro upon detergent removal. Accordingly, punctae formation can be prevented by shielding the Wingless lipid, in vivo with excess Dally-like protein (Dlp) or in vitro with liposomes. Our results show that membrane lipid composition modulates the orderly transfer of Wingless lipid from Wntless to the inner endosomal surface thus preventing aggregation and ensuring seamless secretion in the basolateral space.

cell biology↗

bioRxiv2025

Insect wings arose with a genetic circuit that extends the useful range of a BMP morphogen

Morphogens are produced by a subset of cells to trigger a signalling gradient that provides positional information to surrounding tissues. At increasing distances from the source, the dwindling number of morphogen molecules is expected to constrain the useful range of morphogen gradients. We have identified a genetic circuit that counteracts this limitation in developing wings of Drosophila by boosting BMP signalling at the distal end of the gradient without amplifying the signal near the source. This circuit involves Brinker, a transcription factor that represses BMP target genes while itself being repressed by BMP signalling. We suggest that temporal averaging inherent to the production of the inverse Brk gradient contributes to the enhancement of the positional information far from the Dpp source. Despite being a core component of BMP signalling in flies, Brinker is exclusively found in insects, likely in all insect species. Genomic analysis across a wide range of insects and gene expression analysis in limb primordia of the apterygote Thermobia domestica suggests that Brinker is an insect-specific innovation that was subsequently wired into the BMP signalling network in pterygotes, perhaps to enable wing development.

developmental biology↗

bioRxiv2024

Growth-induced physiological hypoxia correlates with growth deceleration during normal development

Growth deceleration is a universal feature of growth during development: most organs and tissues slow down their growth rate much before growth termination. Using transcriptomics analysis, we show that during their two-day period of growth deceleration, wing imaginal discs of Drosophila undergo a progressive metabolic shift away from oxidative phosphorylation and towards glycolysis. We then develop an ultra-sensitive reporter HIF-1 activity, which reveals that imaginal discs become increasingly hypoxic during development in normoxic conditions, suggesting that limiting oxygen supply could underlie growth deceleration. Growth is energetically expensive and thus expected to contribute, indirectly, to oxygen consumption. Indeed, excess TOR signalling, a key stimulator of growth, triggers hypoxia locally and systemically, highlighting the need to rein in growth when oxygen becomes limiting. This is achieved by a negative feedback loop whereby the classic TOR-inhibitory function of HIF-1 is deployed in response to developmental hypoxia. The absence of Sima/HIF-1 leads to cellular stress, which is alleviated by reduced TOR signalling. Conversely, a small increase in oxygen supply reduces the stress induced by excess TOR activity. We conclude that mild hypoxia is a normal feature of organ development and that Sima/HIF-1 prevents growth-induced oxygen demand from exceeding supply.

developmental biology↗

bioRxiv2023

Drosophila AHR limits tumor growth and stem cell proliferation in the intestine

The aryl hydrocarbon receptor (AHR) plays important roles in intestinal homeostasis, limiting tumour growth and promoting differentiation in the intestinal epithelium. Spineless, the Drosophila homolog of AHR, has only been studied in the context of development but not in the adult intestine. Here, we show that spineless is upregulated in the adult intestinal epithelium after infection with Pseudomonas entomophila (P.e.). Spineless knockdown increased stem cell proliferation following infection-induced injury. Spineless overexpression limited intestinal stem cell proliferation and reduced survival after infection. In two tumour models, using either Notch RNAi or constitutively active Yorkie, Spineless suppressed tumour growth and doubled the lifespan of tumour-bearing flies. At the transcriptional level it reversed the gene expression changes induced in Yorkie tumours, counteracting cell proliferation and altered metabolism. These findings demonstrate a new role for Spineless in the adult Drosophila midgut and highlight the evolutionarily conserved functions of AHR/Spineless in the control of proliferation and differentiation of the intestinal epithelium.

cancer biology↗

bioRxiv2023

Signalling-dependent refinement of cell fate choice during tissue remodelling

How biological form emerges from cell fate decisions and tissue remodelling is a fundamental question in development biology. However, an understanding of how these processes operate side-by-side to set precise and robust patterns is largely missing. Here, we investigate this interplay during the process of vein refinement in the Drosophila pupal wing. By following reporters of signalling activity dynamically, together with tissue flows, we show that longitudinal vein refinement arises from a combination of local tissue deformation and cell fate adjustments controlled by a signalling network involving Notch, Dpp, and EGFR. Perturbing large-scale convergence and extension tissue flows does not affect vein refinement, showing that pre-patterned vein domains are able to intrinsically refine to the correct width. A minimal biophysical description taking into account key signalling interactions recapitulates the intrinsic tissue ability to establish a thin, regular vein independently of large-scale tissue flows. Supporting this prediction, artificial proveins optogenetically generated orthogonal to the axis of wing elongation refine against large-scale flows. Overall, we find that signalling-mediated updating of cell fate is a key contributor to reproducible patterning.

developmental biology↗

bioRxiv2023

The ecdysone receptor promotes or suppresses proliferation according toligand level

Steroid hormones control various cellular activities in a context-dependent manner. For example, ecdysone, which acts through a type II nuclear receptor, has seemingly opposite effects in Drosophila wing precursors, promoting proliferation during larval stages, and triggering proliferation arrest at pupariation. We find that wing precursors proliferate normally in the complete absence of the ecdysone receptor (EcR), whether ecdysone is present or not, suggesting that ecdysone overrides a default antiproliferative activity of the receptor. By contrast, termination of proliferation by high concentration of 20E at the end of larval life involves conventional gene regulation by the ligand-receptor complex. The switch from one mode of regulation to the other is determined by ligand level, as measured with a calibrated EcR transcriptional reporter and ex vivo proliferation assays. Accordingly, RNA Seq analysis uncovers distinct transcriptional responses to different doses of ecdysone. Some genes are only activated at high doses (high threshold targets) and likely to comprise genes that stop proliferation at pupariation, when ecdysone titres are high. We find that other target genes respond to all physiological concentrations of ecdysone. Some of these genes are known to promote proliferation and could therefore contribute to the pro-proliferation activity of low-level ecdysone. Finally, we show mathematically and with synthetic reporters that relatively simple combinations of regulatory elements can recapitulate the behaviour of both types of target genes.

developmental biology↗

bioRxiv2020

Frizzled-dependent Planar Cell Polarity without Wnt Ligands

Planar cell polarity (PCP) organizes the orientation of cellular protrusions and migratory activity within the tissue plane. PCP establishment involves the subcellular polarization of core PCP components. It has been suggested Wnt gradients could provide a global cue that coordinates local PCP with tissue axes. Here we dissect the role of Wnt ligands in the orientation of hairs of Drosophila wings, an established system for study of PCP. We found that PCP was normal in quintuple mutant wings that rely solely on membrane-tethered Wingless for Wnt signaling, suggesting that a Wnt gradient is not required. We then used a nanobody-based approach to trap Wntless in the endoplasmic reticulum, and hence prevent all Wnt secretion, specifically during the period of PCP establishment. PCP was still established. We conclude that, even though Wnt ligands could contribute to PCP, they are not essential, and another global cue must exist for tissue-wide polarization.

developmental biology↗

bioRxiv2018

Apical caspase reporters uncover unknown stages of apoptosis and enable ready visualization of undead cells

The caspase-mediated regulation of many cellular processes, including apoptosis, justifies the substantial interest in understanding all of the biological features of these enzymes. To complement functional assays, it is critical to identify caspase-activating cells in live tissues. Our work describes new caspase-reporters that, for the first time, provide direct information concerning the initial steps of the caspase activation cascade in Drosophila tissues. One of our caspase-sensors has capitalized on the rapid subcellular localization change of a fluorescent marker to uncover novel cellular apoptotic events. These refer to the actin-mediated positioning of the nucleus before cell delamination. The other construct has benefited from a caspase-induced nuclear translocation of a QF transcription factor. This feature enables the genetic manipulation of caspase-activating cells, whilst showing the spatio-temporal patterns of apical caspase activation. Collectively, our sensors offer new experimental opportunities that are already illuminating unknown aspects of caspase-dependent processes in apoptotic and non-apoptotic cellular scenarios.\n\nSummary statementWe describe a novel set of caspase sensors that directly detect early caspase activation. The exclusive features of our reporters uncovered unknown stages of apoptosis and properties of caspase-activating cells.

cell biology↗