Biology subjects

Dupuis, L.

Publications and source records attributed to Dupuis, L..

13 recordsLinked to original sources

bioRxiv2026

Astrocyte diversity and aging in the mouse lemur primate brain

Astrocytes play key roles in maintaining brain homeostasis, metabolism, and neurovascular integrity, yet their diversity and age-related modulation remain insufficiently understood, particularly across primate lineages. While rodent studies have generated extensive knowledge, notable species differences highlight the need for comparative analyses in non-human primates. The gray mouse lemur (Microcebus murinus), a small primate widely used in aging research, offers a valuable but underexplored model for studying astroglial aging. In this study, we characterized astrocyte distribution, morphology, and reactivity in 17 mouse lemurs aged 1.0-11.5 years using GFAP and vimentin immunohistochemistry. We identified marked regional and morphological heterogeneity, with dense astrocytic labeling in white matter, hippocampus, and sparse but diverse cortical populations. Distinct astrocyte subtypes--including fibrous, protoplasmic, projection, pial and subpial interlaminar, radial glia-like cells, tanycytes--were documented. Varicosity-bearing processes were common across multiple astroglial subtypes and may indicate altered physiological states. Quantitative analyses revealed pronounced age-related increases in astrocytic reactivity, particularly in white matter and interlaminar astrocytes. Cortical and hippocampal changes were comparatively modest. These findings indicate region-specific astrocytic vulnerability during aging and support the translational value of the mouse lemur for investigating glial aging in primates. Main PointsO_LIThe mouse lemur is the smallest primate on earth with a key role to understand primate brain characteristics. C_LIO_LIWe characterized seven different astrocyte subtypes: from fibrous to primate-specific astrocyte as interlaminar astrocytes in different brain regions of this primate. C_LIO_LIVaricosities were reported in different astrocyte subtypes found close to brain borders. C_LIO_LIMain age-related changes concerned fibrous astrocytes in the white matter and interlaminar astrocytes at the cortical border. C_LI

neuroscience↗

bioRxiv2025

Repetitive Trans-spinal magnetic stimulation Promotes Repair in Inflammatory Spinal Cord Injury Through Sex-Dependent Immune Modulation

Spinal cord injuries (SCI), whether traumatic or inflammatory such as transverse myelitis (TM), are characterized by severe neuroinflammation, demyelination, and long-term disabilities. Current treatments remain limited, highlighting the need for novel non-invasive therapeutic approaches. Repetitive magnetic stimulation (RMS) has emerged as a promising strategy, but its mechanisms and efficacy in inflammatory contexts remain poorly described. Here, we investigated the effects of RMS applied as trans-spinal RMS (rTSMS) in a mouse model of focal spinal cord demyelination induced by lysophosphatidylcholine (LPC). When applied one day after LPC injection, rTSMS reduced inflammation, demyelination, and fibroglial scar formation, while promoting early locomotor recovery in both sexes. In contrast, when treatment was initiated three days after LPC injection, corresponding to the peak of motor deficits, rTSMS conferred tissue protection and functional benefits only in female mice. RNA sequencing analyses revealed sex-dependent immune modulation: in females, rTSMS primarily regulated adaptive T cell-related pathways, whereas in males, it mainly targeted innate immune responses such as neutrophil activity and phagocytosis. Complementary in vitro experiments using microglial and macrophage cultures further demonstrated that RMS modulates transcriptomic responses differently depending on cell type and inflammatory state. Specifically, RMS attenuated IL-1-induced pro-inflammatory signaling in macrophages and completely abolished these effects in microglia. Altogether, our findings establish rTSMS as a non-invasive therapy capable of reducing neuroinflammation and demyelination in inflammatory SCI, with pronounced sex-dependent effects. By uncovering distinct immune pathways engaged in male and female mice, this study provides mechanistic insights into rTSMS action and opens perspectives for its translational use in neuroinflammatory diseases.

neuroscience↗

bioRxiv2025

Increased white matter microglial reaction and perivascular macrophages in the aging microcebe primate

As populations age, the incidence of neurodegenerative disorders is rising. Early age-related neuropathological changes are the breeding ground for the development of these disorders. Microglia are the resident macrophages of the central nervous system. They play crucial roles in maintaining brain homeostasis, yet their age-related changes remain not fully understood. While age-related microglia changes have been strongly characterized in rodents, studies in non-human primates are scarce. The microcebe primate (mouse lemur (Microcebus murinus)) is widely used as a model for cerebral aging and to investigate age-related neurodegenerative processes. HLA-DR is a major histocompatibility class II cell surface receptor which presents antigens to cells of the immune response. It is a major marker of microglia reaction. In this study, we explored microglia in the whole brains of middle-aged and old microcebes using HLA-DR immunolabeling. We analyzed microglial morphology and quantified HLA-DR+ cell density and protein expression. A wide range of microglial morphologies was observed in the white matter, including thin processes microglia, "rod-like" elongated and polarized shape, hypertrophic, and amoeboid microglia. Aging was associated with increased HLA-DR+ microglial expression in the white matter while very few HLA-DR+ microglia were observed in the parenchyma of cortical gray matter regions. A second finding was the higher number of HLA-DR+ perivascular macrophages in old animals. This study in a primate outlines that, in the absence of neurodegenerative processes, the most prominent signs of age-related microglia/macrophage changes are region-specific and concern white matter and perivascular regions. This emphasizes the need to target these regions to prevent cerebral aging. Main PointsO_LIHLA-DR+ microglia in Microcebus murinus primate show diverse morphologies and increase with age in white matter. C_LIO_LIHLA-DR+ perivascular macrophage load increase in aged animals. C_LI Table of Contents Image (TOCI) O_FIG O_LINKSMALLFIG WIDTH=167 HEIGHT=200 SRC="FIGDIR/small/645519v2_ufig1.gif" ALT="Figure 1"> View larger version (56K): org.highwire.dtl.DTLVardef@edb574org.highwire.dtl.DTLVardef@23f606org.highwire.dtl.DTLVardef@ed2e0borg.highwire.dtl.DTLVardef@169f059_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

CREB3 gain of function variants protect against ALS

Amyotrophic lateral sclerosis (ALS) is a fatal and rapidly evolving neurodegenerative disease that arises from the loss of glutamatergic corticospinal neurons (CSN) and cholinergic motoneurons (MN). The disease is mostly sporadic, but genetics is expected to highly contribute to disease onset and progression. Genome wide association studies identified a few genetic disease modifiers, mostly associated with a negative outcome, and demonstrated that ALS is primarily a disease of excitatory glutamatergic neurons. Here, we reasoned that at least a subpart of genetic disease modifiers may directly modulate the molecular pathways selectively activated in vulnerable neurons as the disease progresses, and concentrated on CSN for their selective vulnerability and glutamatergic identity. We implemented comparative cross-species transcriptomics using snRNAseq data from postmortem motor cortex of ALS patients and controls, and longitudinal RNAseq data from anatomically defined CSN purified from the Sod1G86R mouse model of ALS. We report that disease vulnerable neuronal populations undergo ER stress and altered mRNA translation, and identify the transcription factor CREB3 and its regulatory network as a resilience marker of neuronal dysfunction in ALS. Using genetic and epidemiologic analyses we further identify the rare variant CREB3R119G (rs11538707) as a new disease modifier in ALS. Through gain of function, CREB3R119G decreases both the risk of developing ALS and the progression rate of ALS patients. This study reveals novel genetic variants that protect against ALS and highlights the benefice of combining transcriptomics and genetics to identify new disease modifiers and therapeutic targets.

genomics↗

bioRxiv2024

FUS controls muscle differentiation and structure through LLPS mediated recruitment of MEF2 and ETV5

FUS is an RNA binding protein mutated in amyotrophic lateral sclerosis (ALS), a neurodegenerative disease characterized by progressive muscle weakness. We show that ALS-associated FUS mutations lead to ultrastructural defects in muscle of FUS-ALS patients, with disruption of sarcomeres and mitochondria. Studies in mouse and Drosophila models demonstrate an evolutionary-conserved cell autonomous function of FUS in muscle development. Mechanistically, FUS is required for transcription of MEF2 dependent genes, binds to the promoter of genes bound by ETS transcription factors in particular ETV5 and co-activates transcription of MEF2 dependent genes with ETV5. FUS phase separates with ETV5 and MEF2A, and MEF2A binding to FUS is potentiated by ETV5. Last, Etv5 haploinsufficiency exacerbates muscle weakness in a mouse model of FUS-ALS. These findings establish FUS as an essential protein for skeletal muscle structure through its phase separation-dependent recruitment of ETV5 and MEF2, defining a novel pathway compromised in FUS-ALS.

neuroscience↗

bioRxiv2024

CausalXtract: a flexible pipeline to extract causal effects from live-cell time-lapse imaging data

Live-cell microscopy routinely provides massive amount of time-lapse images of complex cellular systems under various physiological or therapeutic conditions. However, this wealth of data remains difficult to interpret in terms of causal effects. Here, we describe CausalXtract, a flexible computational pipeline that discovers causal and possibly time-lagged effects from morphodynamic features and cell-cell interactions in live-cell imaging data. CausalXtract methodology combines network-based and information-based frameworks, which is shown to discover causal effects overlooked by classical Granger and Schreiber causality approaches. We showcase the use of CausalXtract to uncover novel causal effects in a tumor-on-chip cellular ecosystem under therapeutically relevant conditions. In particular, we find that cancer associated fibroblasts directly inhibit cancer cell apoptosis, independently from anti-cancer treatment. CausalXtract uncovers also multiple antagonistic effects at different time delays. Hence, CausalXtract provides a unique computational tool to interpret live-cell imaging data for a range of fundamental and translational research applications.

systems biology↗

bioRxiv2024

Cellular Modeling of CLN6 with IPSC-derived Neurons and Glia

Neuronal ceroid lipofuscinosis (NCL), type 6 (CLN6) is a neurodegenerative disorder associated with progressive neurodegeneration leading to dementia, seizures, and retinopathy. CLN6 encodes a resident-ER protein involved in trafficking lysosomal proteins to the Golgi. CLN6p deficiency results in lysosomal dysfunction and deposition of storage material comprised of Nile Red+ lipids/proteolipids that include subunit C of the mitochondrial ATP synthase (SUBC). White matter involvement has been recently noted in several CLN6 animal models and several CLN6 subjects had neuroimaging was consistent with leukodystrophy. CLN6 patient-derived induced pluripotent stem cells (IPSCs) were generated from several of these subjects. IPSCs were differentiated into oligodendroglia or neurons using well-established small-molecule protocols. A doxycycline-inducible transgenic system expressing neurogenin-2 (the I3N-system) was also used to generate clonal IPSC-lines (I3N-IPSCs) that could be rapidly differentiated into neurons (I3N-neurons). All CLN6 IPSC-derived neural cell lines developed significant storage material, CLN6-I3N-neuron lines revealed significant Nile Red+ and SUBC+ storage within three and seven days of neuronal induction, respectively. CLN6-I3N-neurons had decreased tripeptidyl peptidase-1 activity, increased Golgi area, along with increased LAMP1+ in cell bodies and neurites. SUBC+ signal co-localized with LAMP1+ signal. Bulk-transcriptomic evaluation of control- and CLN6-I3N-neurons identified >1300 differentially-expressed genes (DEGs) with Gene Ontogeny (GO) Enrichment and Canonical Pathway Analyses having significant changes in lysosomal, axonal, synaptic, and neuronal-apoptotic gene pathways. These findings indicate that CLN6-IPSCs and CLN6-I3N-IPSCs are appropriate cellular models for this disorder. These I3N-neuron models may be particularly valuable for developing therapeutic interventions with high-throughput drug screening assays and/or gene therapy.

neuroscience↗

bioRxiv2022

A conditional null allele of Dync1h1 enables targeted analyses of dynein roles in neuronal length sensing and neurological disorders

Size homeostasis is one of the most fundamental aspects of biology and it is particularly important for large cells as neurons. We have previously proposed a motor-dependent length-sensing and growth-regulating mechanism wherein a partial reduction in the levels of microtubule motor proteins should lead to accelerated neuronal growth. This prediction was originally validated in sensory neurons heterozygous for the Loa point mutation in dynein heavy chain 1 (Dync1h1Loa). Here we describe a new mouse model with a conditional allele allowing deletion of exons 24-25 in Dync1h1. Homozygous Islet1-Cre deletion of Dync1h1 is embryonic lethal, but heterozygous animals (Isl1-Dync1h1+/-) survive to adulthood with approximately 50% dynein expression in targeted cell types. Isl1-Dync1h1+/- adult sensory neurons reveal an accelerated growth phenotype, similar to that previously reported in Dync1h1Loa neurons. Moreover, Isl1-Dync1h1+/- mice show mild impairments in gait, proprioception and tactile sensation; and slightly impaired recovery from peripheral nerve injury. Thus, conditional deletion of Dync1h1 exons 24-25 enables targeted studies of the role of dynein in neuronal growth and neurological disorders.

neuroscience↗

bioRxiv2020

Wild-type FUS corrects ALS-like disease induced by cytoplasmic mutant FUS through autoregulation.

Mutations in FUS, an RNA-binding protein involved in multiple steps of RNA metabolism, are associated with the most severe forms of amyotrophic lateral sclerosis (ALS). Accumulation of cytoplasmic FUS is likely to be a major culprit in the toxicity of FUS mutations. Thus, preventing cytoplasmic mislocalization of the FUS protein may represent a valuable therapeutic strategy. FUS binds to its own pre-mRNA creating an autoregulatory loop efficiently buffering FUS excess through multiple proposed mechanisms including retention of introns 6 and/or 7. Here, we introduced a wild-type FUS gene allele, retaining all intronic sequences, in mice whose heterozygous or homozygous expression of a cytoplasmically retained FUS protein (Fus{Delta}NLS) was previously shown to provoke ALS-like disease or postnatal lethality, respectively. Wild-type FUS completely rescued the early lethality caused by the two Fus{Delta}NLS alleles, and improved age-dependent motor deficit and reduced lifespan associated with the heterozygous expression of Fus{Delta}NLS. Mechanistically, wild-type FUS decreased the load of cytoplasmic FUS, increased exon 7 skipping and retention of introns 6 and 7 in the endogenous mouse Fus mRNA, leading to decreased expression of the mutant mRNA. Thus, the wild-type FUS allele activates the homeostatic autoregulatory loop, maintaining constant FUS levels and decreasing the mutant protein in the cytoplasm. These results provide proof of concept that an autoregulatory competent wild-type FUS expression could protect against this devastating, currently intractable, neurodegenerative disease.

neuroscience↗

bioRxiv2020

Disruption of orbitofrontal-hypothalamic projections in a murine ALS model and human patients

Increased catabolism is a new clinical manifestation of Amyotrophic Lateral Sclerosis. A dysfunction of lateral hypothalamus may drive hypermetabolism in ALS; however, Its causes and anatomical substrates are unknown. We hypothesize that disruption cortico-hypothalamic circuits may impair energy homeostasis in ALS. We used rAAV2 for large-scale projection mapping and image analysis pipeline based on Wholebrain and Ilastik to quantify projections from the forebrain to the latera hypothalamus of the SOD1(G93A) ALS mouse model as well as of the Fus{Delta}NLS ALS mouse model. Expanded projections from agranular Insula, ventrolateral orbitofrontal and secondary motor cortex to lateral hypothalamus were found in two independent cohorts of the hypermetabolic SOD1(G93A) ALS model. The non-hypermetabolic Fus{Delta}NLS ALS mouse model display a loss of projections from motor cortex but no change in projections from insula and orbitofronal cortex. 3T DTI-MRI data on 83 ALS patients and 65 controls confirmed the disruption of the orbitofrontal-hypothalamic tract in ALS patients. Converging murine and human data demonstrate the selective disruption of hypothalamic inputs in ALS as a factor contributing to the origin of hypermetabolism. Significance statementWe provide a circuit perspective of the recently identified and medically relevant hyper-metabolic phenotype of Amyotrophic Lateral Sclerosis. We demonstrate the selective involvement of orbitofrontal, insular and motor cortex projections to hypothalamus in murine ALS models and in human patients. The enhanced pipeline for large-scale registration, segmentation projections mapping, the identification of new circuits target of neurodegeneration, and the relevance of these circuits in metabolic disturbances make this work relevant not only for the investigation of ALS but also for other neurodegenerative disease as well as for all conditions characterized by systemic energy imbalances.

neuroscience↗

bioRxiv2020

Cytoplasmic accumulation of FUS triggers early behavioral alterations linked to cortical neuronal hyperactivity and defects in inhibitory synapses

Gene mutations causing cytoplasmic mislocalization of the RNA-binding protein FUS, lead to severe forms of amyotrophic lateral sclerosis (ALS). Cytoplasmic accumulation of FUS is also observed in other diseases, with unknown consequences. Here, we show that cytoplasmic mislocalization of FUS drives behavioral abnormalities in knock-in mice, including locomotor hyperactivity and alterations in social interactions, in the absence of widespread neuronal loss. Mechanistically, we identified a profound increase in neuronal activity in the frontal cortex of Fus knock-in mice in vivo. Importantly, RNAseq analysis suggested involvement of defects in inhibitory neurons, that was confirmed by ultrastructural and morphological defects of inhibitory synapses and increased synaptosomal levels of mRNAs involved in inhibitory neurotransmission. Thus, cytoplasmic FUS triggers inhibitory synaptic deficits, leading to increased neuronal activity and behavioral phenotypes. FUS mislocalization may trigger deleterious phenotypes beyond motor neuron impairment in ALS, but also in other neurodegenerative diseases with FUS mislocalization.

neuroscience↗

bioRxiv2020

Synaptic accumulation of FUS triggers age-dependent misregulation of inhibitory synapses in ALS-FUS mice

FUS is a primarily nuclear RNA-binding protein with important roles in RNA processing and transport. FUS mutations disrupting its nuclear localization characterize a subset of amyotrophic lateral sclerosis (ALS-FUS) patients, through an unidentified pathological mechanism. FUS regulates nuclear RNAs, but its role at the synapse is poorly understood. Here, we used super-resolution imaging to determine the physiological localization of extranuclear, neuronal FUS and found it predominantly near the vesicle reserve pool of presynaptic sites. Using CLIP-seq on synaptoneurosome preparations, we identified synaptic RNA targets of FUS that are associated with synapse organization and plasticity. Synaptic FUS was significantly increased in a knock-in mouse model of ALS-FUS, at presymptomatic stages, accompanied by alterations in density and size of GABAergic synapses. RNA-seq of synaptoneurosomes highlighted age-dependent dysregulation of glutamatergic and GABAergic synapses. Our study indicates that FUS accumulation at the synapse in early stages of ALS-FUS results in synaptic impairment, potentially representing an initial trigger of neurodegeneration.

neuroscience↗

bioRxiv2019

Atxn2-CAG100-KnockIn mouse spinal cord shows progressive TDP43 pathology associated with cholesterol biosynthesis suppression

Large polyglutamine expansions in Ataxin-2 (ATXN2) cause multi-system nervous atrophy in Spinocerebellar Ataxia type 2 (SCA2). Intermediate size expansions carry a risk for selective motor neuron degeneration, known as Amyotrophic Lateral Sclerosis (ALS). Conversely, the depletion of ATXN2 prevents disease progression in ALS. Although ATXN2 interacts directly with RNA, and in ALS pathogenesis there is a crucial role of RNA toxicity, the affected functional pathways remain ill defined. Here, we examined an authentic SCA2 mouse model with Atxn2-CAG100-KnockIn for a first definition of molecular mechanisms in spinal cord pathology. Neurophysiology of lower limbs detected sensory neuropathy rather than motor denervation. Triple immunofluorescence demonstrated cytosolic ATXN2 aggregates sequestrating TDP43 and TIA1 from the nucleus. In immunoblots, this was accompanied by elevated CASP3, RIPK1 and PQBP1 abundance. RT-qPCR showed increase of Grn, Tlr7 and Rnaset2 mRNA versus Eif5a2, Dcp2, Uhmk1 and Kif5a decrease. These SCA2 findings overlap well with known ALS features. Similar to other ataxias and dystonias, decreased mRNA levels for Unc80, Tacr1, Gnal, Ano3, Kcna2, Elovl5 and Cdr1 contrasted with Gpnmb increase. Preterminal stage tissue showed strongly activated microglia containing ATXN2 aggregates, with parallel astrogliosis. Global transcriptome profiles from stages of incipient motor deficit versus preterminal age identified molecules with progressive downregulation, where a cluster of cholesterol biosynthesis enzymes including Dhcr24, Msmo1, Idi1 and Hmgcs1 was prominent. Gas chromatography demonstrated a massive loss of crucial cholesterol precursor metabolites. Overall, the ATXN2 protein aggregation process affects diverse subcellular compartments, in particular stress granules, endoplasmic reticulum and receptor tyrosine kinase signaling. These findings identify new targets and potential biomarkers for neuroprotective therapies.

neuroscience↗