Biology subjects

Marie, P.

Publications and source records attributed to Marie, P..

8 recordsLinked to original sources

bioRxiv2026

Cerebral microthrombi promote focal Cav-1-dependent blood-brain barrier impairment, triggering neuroinflammation and neuronal damage after traumatic brain injury

Traumatic brain injury (TBI) is frequently accompanied by blood-brain barrier (BBB) dysfunction, yet the microvascular events that initiate barrier failure and secondary neural injury remain poorly understood. Using highly sensitive fluorescent nanoscale tracers, correlative light and electron microscopy, single-cell transcriptomics, and genetic manipulation of Caveolin-1 (Cav-1), we show that BBB leakage after TBI in mice occurs focally at sites of cerebral microthrombus formation. Endothelial cells adjacent to microthrombi remain structurally intact, but exhibit a distinct transcriptional program enriched in both thrombosis- and transcytosis-related genes, including Cav-1. Microthrombi promote Cav-1-dependent transcytosis and size-selective extravasation of blood-borne proteins, exposing the surrounding parenchyma to circulating factors and inducing focal microglia activation and neuronal damage in vivo. In human induced pluripotent stem cell-derived neurons, these proteins directly impaired neuronal structure and network function. Genetic deletion of Cav-1 markedly reduces microthrombus-associated BBB leakage, immune-cell diapedesis, microglial activation and neuronal loss, whereas endothelial re-expression of Cav-1 using AAVs restores leakage. Human TBI data reveal early dynamic coagulation dysregulation associated with adverse clinical outcome, focal cerebral vascular injury and endothelial transcriptional signatures consistent with reduced barrier integrity and increased caveolae-associated transport. Together, these findings identify cerebral microthrombi as focal sites of Cav-1-dependent BBB dysfunction and establish pathological endothelial transcytosis as a mechanistic link between post-traumatic microvascular thrombosis, blood protein extravasation and secondary neuronal injury. Targeting Cav-1-dependent transcytosis may therefore provide a strategy to limit pathological BBB permeability and secondary injury after TBI.

neuroscience↗

bioRxiv2023

FGF19 and its analog Aldafermin cooperate with MYC to induce aggressive hepatocarcinogenesis

FGF19 hormone has pleiotropic metabolic functions, notably the modulation of insulin sensitivity, glucose/lipid metabolism and energy homeostasis. On top of its physiological metabolic role, FGF19 has been identified as a potentially targetable oncogenic driver, notably in hepatocellular carcinoma (HCC). Nevertheless, FGF19 remained an attractive candidate for treatment of metabolic disease, prompting the development of analogs uncoupling its metabolic and tumor-promoting activities. Using pre-clinical mice models of somatic mutation driven HCC, we assessed the oncogenicity of FGF19 in combination with frequent HCC tumorigenic alterations: p53 inactivation, CTNNB1 mutation, CCND1 or MYC overexpression. Our data revealed a strong oncogenic cooperation between FGF19 and MYC. Most importantly, we show that this oncogenic synergy is conserved with a FGF19-analog Aldafermin (NGM282), designed to solely mimic the hormones metabolic functions. In particular, even a short systemic treatment with recombinant proteins triggered rapid appearance of proliferative foci of MYC-expressing hepatocytes. The fact that FGF19 analog Aldafermin is not fully devoid of the hormones oncogenic properties raises concerns in the context of its potential use for patients with damaged, mutation-prone liver.

cancer biology↗

bioRxiv2023

Gene-to-Gene Coordinated Regulation of Transcription and Alternative splicing by 3D Chromatin Remodeling upon NF-κB activation

The p65/RelA factor of NF-{kappa}B plays a pivotal role in coordinating gene expression in response to diverse stimuli, including viral infections. At the chromatin level, p65/RelA regulates gene transcription and alternative splicing (AS) through promoter enrichment and genomic exon occupancy, respectively. However, the mechanisms underlying the coordination of these processes across distinct genes remain elusive. In this study, we employed the HTLV-1 Tax oncoprotein, a potent activator of NF-{kappa}B, to investigate the integrative relationship between 3D chromatin architecture, NF-{kappa}B-regulated transcription and AS. Our analysis revealed that Tax induces a pronounced reorganization of the 3D genome, resulting in the formation of multigene complexes that comprise genes regulated either transcriptionally or through AS. Notably, we found that the Tax-induced gene-gene contact between the two master genes NFKBIA and RELA is associated with their differential regulation in gene expression and AS, respectively. Through dCas9-mediated approaches, we demonstrated that NFKBIA-RELA interaction is required for AS regulation and is caused by an intragenic enrichment of p65/RelA on RELA. Our findings shed light on new regulatory mechanisms upon HTLV-1 Tax and underscore the integral role of p65/RelA in coordinated regulation of NF-{kappa}B-responsive genes at both transcriptional and AS levels in the context of the 3D genome.

molecular biology↗

bioRxiv2020

Accessory ESCRT-III proteins selectively regulate Rab11-exosome biogenesis in Drosophila secondary cells

Exosomes are secreted nanovesicles with potent signalling activity that are initially formed as intraluminal vesicles (ILVs) in multivesicular endosomes, which subsequently fuse with the plasma membrane. These ILVs are made in both late endosomes and recycling endosomes, the latter marked by the small GTPase Rab11 and generating exosomes with different cargos and functions. Core proteins within four Endosomal Sorting Complex Required for Transport (ESCRT) assemblies (0-III) play key sequential roles in late endosomal exosome biogenesis and ILV-mediated destruction of ubiquitinylated cargos through the endolysosomal system. They also control additional cellular processes, such as cytokinesis and other vesicle budding. By contrast, the functions of several accessory ESCRTs are not well defined. Here we assess the ESCRT-dependency of Rab11-exosomes, using RNA knockdown in Drosophila secondary cells (SCs) of the male accessory gland, which have unusually enlarged Rab11-positive compartments. Unexpectedly, not only are core proteins in all four ESCRT complexes required for Rab11-exosome formation, but also accessory ESCRT-III proteins, CHMP1, CHMP5 and IST1. Suppressing expression of these accessory proteins does not affect other aspects of cell morphology, unlike most core ESCRT knockdowns, and does not lead to accumulation of ubiquitinylated cargos. We conclude that accessory ESCRT-III components have a specific and potentially ubiquitin-independent role in Rab11-exosome generation, which might provide a target for blocking the pro-tumorigenic activities of these vesicles in cancer.

cell biology↗

bioRxiv2020

Drosophila Sex Peptide Controls the Assembly of Lipid Microcarriers in Seminal Fluid

Seminal fluid plays an essential role in promoting male reproductive success and modulating female physiology and behaviour. In the fruit fly, Drosophila melanogaster, Sex Peptide (SP) is the best-characterised protein mediator of these effects. It is secreted from the paired male accessory glands (AGs), which, like the mammalian prostate and seminal vesicles, generate most of the seminal fluid contents. After mating, SP binds to spermatozoa and is retained in the female sperm storage organs. It is gradually released by proteolytic cleavage and induces several long-term post-mating responses including ovulation, elevated feeding and reduced receptivity to remating, primarily signalling through the SP receptor (SPR). Here, we demonstrate a previously unsuspected SPR-independent function for SP. We show that, in the AG lumen, SP and secreted proteins with membrane-binding anchors are carried on abundant, large neutral lipid-containing microcarriers, also found in other SP-expressing Drosophila species. These microcarriers are transferred to females during mating, where they rapidly disassemble. Remarkably, SP is a key assembly factor for microcarriers and is also required for the female disassembly process to occur normally. Males expressing non-functional SP mutant proteins that affect SPs binding to and release from sperm in females also do not produce normal microcarriers, suggesting that this male-specific defect contributes to the resulting widespread defects in ejaculate function. Our data therefore reveal a novel role for SP in formation of seminal macromolecular assemblies, which may explain the presence of SP in Drosophila species, which lack the signalling functions seen in D. melanogaster. Significance StatementSeminal fluid plays a critical role in reprogramming female physiology and behaviour to promote male reproductive success. We show in the fruit fly that specific seminal proteins, including the archetypal female-reprogramming molecule Sex Peptide, are stored in male seminal secretions in association with large neutral lipid-containing microcarriers, which rapidly disperse in females. Related structures are also observed in other Sex Peptide-expressing Drosophila species. Males lacking Sex Peptide have structurally defective microcarriers, leading to abnormal cargo loading and transfer to females. Our data reveal that this key signalling molecule in Drosophila seminal fluid is also a microcarrier assembly factor that controls transfer of other seminal factors, and that this may be a more evolutionarily ancient role of this protein.

cell biology↗

bioRxiv2019

Glutamine deprivation regulates the origin and function of cancer cell exosomes

Exosomes are secreted extracellular vesicles (EVs) carrying diverse cargos, which can modulate recipient cell behaviour. They are thought to derive from intraluminal vesicles formed in late endosomal multivesicular bodies (MVBs). An alternate exosome formation mechanism, which is conserved from fly to human, is described here, with exosomes carrying unique cargos, including the GTPase Rab11, generated in Rab11-positive recycling endosomal MVBs. Release of these exosomes from cancer cells is increased by reducing Akt/mechanistic Target of Rapamycin (mTORC1) signalling or depleting the key metabolic substrate glutamine, which diverts membrane flux through recycling endosomes. The resulting vesicles promote tumour cell proliferation and turnover, and modulate blood vessel networks in xenograft mouse models in vivo. Their growth-promoting activity, which is also observed in vitro, is Rab11a-dependent, involves ERK-MAPK-signalling and is inhibited by antibodies against Amphiregulin, an EGFR ligand concentrated on these vesicles. Therefore, glutamine depletion or mTORC1 inhibition stimulates release of Rab11a-exosomes with pro-tumorigenic functions, which we propose promote stress-induced tumour adaptation.

cancer biology↗

bioRxiv2019

Quantitative proteomics and transcriptomics exploration of primary myeloid cells: importance of β tubulin isotypes for bone resorption.

Among hematopoietic cells. osteoclasts (Oc) and immature dendritic cells (Dc) are closely related myeloid cells with distinct functions; Oc participate skeleton maintenance while Dc sample the environment for foreign antigens. Such specificities rely on profound modifications of gene and protein expression during Oc and Dc differentiation. We provide global proteomic and transcriptomic analyses of primary mouse Oc and Dc. based on original SILAC and RNAseq data. We established specific signatures for Oc and Dc including genes and proteins of unknown functions. In particular. we showed that Oc and Dc have the same and {beta} tubulin isotypes repertoire but that Oc express much more {beta} tubulin isotype Tubb6. In both mouse and human Oc. we demonstrate that elevated expression of Tubb6 in Oc is necessary for correct podosomes organization and thus for the structure of the sealing zone. which sustains the bone resorption apparatus. Hence. lowering Tubb6 expression hindered Oc resorption activity. Overall. we highlight here potential new regulators of Oc and Dc biology and illustrate the functional importance of the tubulin isotype repertoire in the biology of differentiated cells. Summary statementThis study provides original proteomic and transcriptomic data of primary myeloid cells. The analysis led to signatures for osteoclasts and for immature dendritic cells including potential new regulators of their specific biology. RNA interference showed in particular that {beta} tubulin isotype Tubb6 participates in osteoclast podosome patterning. sealing zone structure and in the resorption activity.

cell biology↗

bioRxiv2019

Mating Induces Switch From Hormone-Dependent to -Independent Steroid Receptor-Mediated Growth in Drosophila Prostate-Like Cells

Male reproductive glands like the mammalian prostate and the paired Drosophila melanogaster accessory glands secrete seminal fluid components that enhance fecundity. In humans, the prostate grows throughout adult life, stimulated by environmentally regulated endocrine and local androgens. We previously showed that in each fly accessory gland, secondary cells (SCs) and their nuclei also grow in adults, a process enhanced by mating and controlled by bone morphogenetic protein (BMP) signalling. Here we demonstrate that BMP-mediated SC growth is dependent on the receptor for the developmental steroid, ecdysone, whose concentration reflects socio-sexual experience in adults. BMP signalling regulates ecdysone receptor (EcR) levels post-transcriptionally, partly via EcRs N-terminus. Nuclear growth in virgin males is ecdysone-dependent. However, mating activates genome endoreplication to drive additional BMP-mediated nuclear growth via a cell type-specific form of hormone-independent EcR signalling. In virgin males with low ecdysone levels, this mechanism ensures resources are conserved. However, by switching to hormone-independence after mating, this control is overridden to hyper-activate growth of secretory secondary cells. Our data suggest parallels between this physiological, behaviour-induced switch and altered pathological signalling associated with prostate cancer progression.

cell biology↗