Biology subjects

Gay, A.-S.

Publications and source records attributed to Gay, A.-S..

6 recordsLinked to original sources

bioRxiv2026

Zoospore-derived extracellular vesicles in the flagellated stramenopile Phytophthora parasitica

Zoospores are unicellular, wall-less and flagellated cells produced by a number of eukaryotic microorganisms. They allow microbial dispersion, enable the search and location for new sources of nutrients where they aggregate, initiate pathogen-host interactions and communication within microbiota. Little is known about their ability to release bioactive extracellular vesicles (EVs) supporting these adaptations. Here we used electron microscopy to establish that in the biflagellate zoospores of the heterokont and phytopathogenic species Phytophthora parasitica, EV biogenesis occurs from vesicles budding either at cell body plasma membrane or at the front flagellum, in particular from the tubular mastigonemes. Zoospore-conditioned water supernatant was fractionated and characterized by means of morphological, immunochemical, proteomic and lipidomic analyses. Three fractions enriched in cell body, flagella and EVs were obtained by differential ultracentrifugation at 3,000g, 31,000g and 100,000g, respectively, with the EV fraction consisting of small vesicles (100-150 nm). Using mass spectrometry, label-free proteomic analysis of the EV fraction (1,470 proteins) revealed a collection of proteins involved in lipid transport, vesicle membrane and cell wall organization, and tubular mastigoneme architecture, but not in virulence. Label-free quantitative lipidomic analysis (191 lipids) revealed enrichment of EVs in sphingolipids, particularly ceramides compared with the cell body. These findings provide a first hallmark of features characteristic of zoosporic EVs, with ceramides, mastigoneme proteins and the EV-related protein PPTG_13069 containing two tetraspanin MARVELous domains among molecular markers. They define the molecular and cellular principles in understanding zoosporic EV biogenesis within Stramenopiles and intercellular communication between self-aggregating zoospores, with host plant cells or microbiota.

molecular biology↗

bioRxiv2025

Human mammary 3D spheroid models uncover the role of filopodia in breaching the basement membrane to facilitate invasion

Basement membranes (BM) are thin, nanoporous sheets of specialized extracellular matrix (ECM) that line epithelial tissues. They are dynamic structures that serve multiple key functions, as evidenced by numerous diseases, including cancer progression, that are associated with their alterations. Our understanding of the BM and its communication with adjoining epithelial cells remains highly fragmented due to the BMs complex molecular architecture, the lack of molecular tools, limitations in utilizing high-resolution imaging techniques to BMs assembled on tissues, and the difficulty of assessing their functional contributions in vivo. Here, by combining multiple -omics analyses and advanced microscopy methodologies, we characterized the BM from two normal human mammary epithelial cell lines, MCF10 and HMLE, grown as spheroids in 3D matrices. Our findings indicate that the spheroids autonomously assemble a BM exhibiting all the molecular, structural, and biophysical characteristics of physiological BM. Using these minimalist model systems, we show for the first time that the laminins, perlecan, and the hemidesmosomes are all arranged along a shared porous lattice defined by the collagen IV molecular network. Next, we demonstrate that the invasion-promoting PSD4/EFA6B knockout, found in patients with breast cancer, decreases the expression of BM components and their assembly on the spheroid surface. We then show that invasive spheroids develop enlarged pores in the BM via filopodia-like plasma membrane extensions, which further expand in a protease-dependent manner, thereby facilitating the passage of invasive cells. Significance StatementThe basement membrane (BM) directs epithelial tissue architecture and behavior. How tumor cells breach this barrier during invasion remains poorly understood. Using minimalist 3D spheroid models mimicking physiological BM assembly, we reveal a novel infiltration mechanism. Filopodia-like protrusions perforate and widen BM pores. This facilitates cell dissemination through sequential protease-independent and -dependent steps.

cell biology↗

bioRxiv2025

Large extracellular vesicles containing mitochondria (EVMs) derived from Alzheimer disease cells harbor pathologic functional and molecular profiles and spread mitochondrial dysfunctions

In addition to small extracellular vesicles known as exosomes, cells release large extracellular vesicles containing mitochondria (EVMs). However, the molecular and functional characteristics of EVMs, as well as the impact of EVM secretion on the spreading of mitochondrial dysfunction between cells, remain unknown in the context of Alzheimers Disease (AD). Here, we provide an ultrastructural, biochemical, and functional characterization of EVMs isolated from cells expressing the amyloid precursor protein (APP) with the familial Swedish mutation (APPswe). We identified differential proteomic and lipidomic signatures in APPswe-derived EVMs compared to control EVMs and revealed a specific proteomic profile in EVMs isolated from conditioned media of fibroblasts from AD patients at the prodromal stage of the disease. Our findings show that APP-C terminal fragments (APP-CTFs) pathogenic accumulation in cells potentiates EVM secretion through the budding of the plasma membrane. We lastly demonstrated that APP-CTFs loaded EVMs are active carriers of dysfunctional mitochondria that transfer mitochondrial pathology to naive control recipient cells.

neuroscience↗

bioRxiv2023

Multiomics study of CHCHD10S59L-related disease reveals energy metabolism downregulation: OXPHOS and beta-oxidation deficiencies associated with lipids alterations

Mutations in the coiled-coil-helix-coiled-coil-helix domain containing 10 (CHCHD10) gene have been associated with a large clinical spectrum including myopathy, cardiomyopathy and amyotrophic lateral sclerosis (ALS). Herein, we analyzed the metabolic changes induced by the p.S59L CHCHD10 mutation to identify new therapeutic opportunities. Using metabolomic, lipidomic and proteomic analysis we observed a strong alteration of metabolism in plasma and heart of Chchd10S59L/+ mice compared to their wild type littermates at pre-symptomatic and symptomatic stages. In plasma, levels of phospholipids were decreased while those of carnitine derivatives and most of amino acids were increased. The cardiac tissue from Chchd10S59L/+ mice showed a decreased Oxidative Phosphorylation (OXPHOS) and {beta}-oxidation proteins levels as well as tricarboxylic acid cycle (TCA) intermediates and carnitine pathway metabolism. In parallel, lipidomics analysis reveals a drastic change in the lipidome, including triglycerides, cardiolipin and phospholipids. Consistent with this energetic deficiency in cardiac tissue, we show that L-acetylcarnitine supplementation improves the mitochondrial network length in IPS-derived cardiomyocytes from a patient carrying the CHCHD10S59L/+ mutation. These data indicate that a bioenergetic intermediate such as L-acetylcarnitine may restore mitochondrial function in CHCHD10-related disease, due to the reduction in energy deficit that could be compensated by carnitine metabolic pathways.

cell biology↗

bioRxiv2021

OSBP-mediated cholesterol transfer determines epithelial polarity and associated cargo secretion

Golgi lipid environment regulates sorting and cargo secretion. However, the mechanisms that spatiotemporally control the lipid composition of the secretory membranes to drive cargo trafficking are poorly understood. Lipid transfer proteins regulate the concentration of specific lipids at membrane contact sites. We hypothesised that by catalysing cholesterol/PI(4)P exchange at ER-trans-Golgi membrane contact sites the lipid transfer protein oxysterol binding protein (OSBP) affects the secretion of a subset of cargoes. Here, we report that OSBP is a major epithelial protein as its inhibition leads to complete loss of apico-basal polarity. By mapping the OSBP proximity proteome with the biotin ligase TurboID, we found that OSBP controls the secretion of multiple membrane associated proteins, including key polarity determinants such as E-cadherin. Mechanistically, we established that OSBP contributes to E-cadherin secretion by supplying cholesterol to post-Golgi membranes. Importantly, when cells downregulate cell-cell junctions upon epithelial-to-mesenchymal transition, they re-wire their lipid homeostasis and downregulate OSBP as well, thus altering the trafficking of the OSBP-dependent secretory cargoes.

cell biology↗

bioRxiv2021

Tumor protein D54 binds intracellular nanovesicles via an amphipathic lipid packing sensor (ALPS) motif

Tumor Protein D54 (TPD54) is an abundant cytosolic protein that belongs to the TPD52 family, a family of four proteins (TPD52, 53, 54 and 55) that are overexpressed in several cancer cells. Even though the functions of these proteins remain elusive, recent investigations indicate that TPD54 binds to very small cytosolic vesicles with a diameter of ca. 30 nm, half the size of classical transport vesicles (e.g. COPI and COPII). Here, we investigated the mechanism of intracellular nanovesicle capture by TPD54. Bioinformatical analysis suggests that TPD54 contains a small coiled-coil followed by several amphipathic helices, which could fold upon binding to lipid membranes. One of these helices has the physicochemical features of an Amphipathic Lipid Packing Sensor (ALPS) motif, which, in other proteins, enables membrane binding in a curvature-dependent manner. Limited proteolysis, CD spectroscopy, tryptophan fluorescence and cysteine mutagenesis coupled to covalent binding of a membrane sensitive probe show that binding of TPD54 to small liposomes is accompanied by large structural changes in the amphipathic helix region. TPD54 binding to artificial liposomes is very sensitive to liposome size and to lipid unsaturation but is poorly dependent on lipid charge. Cellular investigations confirmed the key role of the ALPS motif in vesicle targeting. Surprisingly, the vesicles selected by TPD54 poorly overlap with those captured by the golgin GMAP-210, a long vesicle tether at the Golgi apparatus, which displays a dimeric coiled-coil architecture and an N-terminal ALPS motif. We propose that TPD54 recognizes nanovesicles through a combination of ALPS-dependent and -independent mechanisms.

cell biology↗