Biology subjects

Marcy, G.

Publications and source records attributed to Marcy, G..

8 recordsLinked to original sources

bioRxiv2026

Selective vulnerability of intracortical projection neurons drives long-term cortical circuit rewiring after perinatal hypoxia

Cortical circuits are built at perinatal times and gradually refined in an activity-dependent manner during a so-called postnatal period of critical plasticity. Although lesions of the central nervous system (CNS) happening during this period typically recover better than those occurring later in life, they are often associated with long-term behavioral deficits. This suggests that neuronal circuits rewiring, in particular within the cortex, may either be incomplete or inappropriate. To address this possibility, we used chronic perinatal hypoxia, a mouse model of very premature birth. We confirmed that chronic hypoxia induced a decrease in cortical thickness frequently observed in very preterm babies, which rapidly recovered 8 days later. To explore the transcriptional correlates of this recovery we next performed single-nuclei transcriptomic analysis of the cortex at short (P11) and long (P45) timepoints following hypoxia. This revealed persistent transcriptional changes within neurons, including of genes involved in mitochondrial metabolism, axonogenesis and synaptogenesis. Further, histological analysis using anterograde and retrograde tracing as well as mitochondrial labelling support persistent alterations in upper cortical neurons resulting in increased cortico-cortical connectivity within the cortex of adult hypoxic mice. Finally, behavioral testing revealed altered social behavior in mice exposed to chronic hypoxia, which amplified with age. Altogether, our results unravel how brain lesions happening early in life, alter normal cortical development and have long term consequences on cortical wiring, contributing to the observed behaviors defects appearing later in life.

neuroscience↗

bioRxiv2026

Netrin-1 Acts as a Guardian of Naive Pluripotency in Human Embryonic Stem Cells

We investigated the role of Netrin-1 (NTN1) in human naive pluripotency using complementary loss- and gain-of-function approaches. In primate embryos and human embryonic stem cells (hESCs), Netrin-1 expression is associated with the naive pluripotent state. Disruption of NTN1 had no detectable effect on hESCs maintained on murine embryonic fibroblasts. However, under sub-optimal culture conditions, NTN1-knockout cells exhibited compromised naive pluripotency, which was rescued with feeder cells overexpressing Netrin-1. Netrin-1 overexpression in hESCs accelerated acquisition of the naive state and markedly increased resistance to differentiation. These effects were accompanied by extensive epigenetic remodeling, including H3K27ac and H2K27me3. Proteomic and phospho-proteomic analyses further revealed rapid Netrin-1-dependent alterations in pathways controlling cell adhesion, signaling, and chromatin regulation. Together, these findings extend the role of Netrin-1 beyond its established functions and identify it as a coordinator of extracellular cues, intracellular signaling, and nuclear regulatory mechanisms that support human naive pluripotency.

cell biology↗

bioRxiv2025

NAD metabolism plays multiple roles in influenza A virus replication in a novel ex vivo model of mouse lung infection.

Despite the availability of prophylactic and therapeutic measures, Influenza A viruses (IAV) remain a major public health concern, causing an estimated 650 000 deaths annually. In this context, the identification of metabolic vulnerabilities of IAV replication could help develop complements to existing antiviral strategies. Here, we used nicotinamide phosphoribosyltransferase (NAMPT) inhibitors to demonstrate that nicotinamide adenine dinucleotide (NAD) is essential for IAV replication and infectious particles production both in vitro and ex vivo. We established an innovant ex vivo model of murine organotypic lung cultures (mOLC) that is pertinent to analyze cell metabolic alterations triggered by IAV infection. Using untargeted metabolomic profiling and spatial transcriptomic analyses, our research revealed that IAV-infection decreased NAD+ levels in mOLCs, while PARPs, a group of NAD+-consuming enzymes, were upregulated. Pharmacological inhibition of the mono-ADP-ribosyl-transferase (mono-ART) activity of PARPs restricted IAV infection ex vivo, suggesting that NAD+ sustains the proviral activity of these enzymes. Overall, our study identifies NAD metabolism as a central regulator of IAV infection, providing redox cofactor to host cell biosynthetic processes and substrate for mono-ART activity. Our results highlight NAMPT and PARP mono-ART activity as promising antiviral targets. Significance StatementViruses are intracellular parasites that rely on the host cellular metabolism for their replication. Our results demonstrate that Influenza A virus (IAV) replication is critically dependent on NAD availability, an enzyme cofactor essential for redox metabolic reactions and a substrate for NAD+-consuming enzymes. Using a novel ex vivo infection model of mouse lung tissue, we found that IAV infection results in NAD depletion and enhanced expression of NAD-consuming PARP enzymes. Inhibitors of NAD biosynthesis and mono(ADP-ribosyl) transferase activity of PARP are restricting viral replication and infectious particles production. These findings highlight the proviral role for PARP mono-ART activity and identify NAMPT and PARP inhibitors as potential host-directed antivirals against IAV.

microbiology↗

bioRxiv2024

Induction of hemodynamic traveling waves by glial-related vasomotion in a rat model of neuroinflammation: implications for functional neuroimaging

BackgroundCerebral hemodynamics are crucial for brain homeostasis and serve as a key proxy for brain activity. Although this process involves coordinated interaction between vessels, neurons and glial cells, its dysregulation in neuroinflammation is not well understood. MethodsWe used in vivo mesoscopic functional ultrasound imaging to monitor cerebral blood volume changes during neuroinflammation in male rats injected with lipopolysaccharide (LPS) in the visual cortex, under resting-state or visual stimulation, combined to advanced ex vivo techniques for glial cell reactivity analysis. FindingsCortical neuroinflammation induced large oscillatory hemodynamic traveling waves in the frequency band of vasomotion ([~]0.1 Hz) in both anesthetized and awake rats. Vasomotor waves traveled through large distances between adjacent penetrating vessels, spanning the entire cortex thickness, and even extending to subcortical areas. Moreover, vasomotion amplitude correlated with microglial morphology changes and was significantly reduced by astrocytic toxins, suggesting that both microglia and astrocytes are involved in the enhancement of vasomotion during neuroinflammation. Notably, functional connectivity was increased under this oscillatory state and functional hyperemia was exacerbated. InterpretationThese findings reveal new spatiotemporal properties of cerebral vasomotion and suggest this is a major component of brain hemodynamics in pathological states. Moreover, reactive microglia and astrocytes are participating to increased vasomotion during neuroinflammation. For the field of functional neuroimaging, our results advocate for considering 0.1 Hz hemodynamic oscillations as an important complement to traditional measurements, particularly in neuroinflammatory conditions. Indeed, brain hemodynamics may provide insights not only into neuronal activity but also glial reactivity. FundingSupported by ANR ("LabCom-NI2D") and Auvergne-Rhone-Alpes Region ("BI2D").

neuroscience↗

bioRxiv2024

Contribution of the neuron-specific ATP1A3 to embryonic spinal circuit emergence

The early neurodevelopmental contributions of ion pumps remain poorly characterized. Combining analysis of public human embryo single-cell transcriptomic datasets and an embryonic chicken model, we found a conserved differentiation sequence whereby spinal cord neurons switch on neuron-specific alpha3 subunit (ATP1A3) of Na+/K+ ATPases. In the chicken model, ATP1A3 is distributed along axons and growth cones. Its knockdown alters axon pathfinding of dorsal interneurons (DIN) that wire spinocerebellar circuits. In mirror of reported electric field (EF)-driven cell migration, we found that DIN axons align in EFs, which was abolished by Na+/K+ ATPase inhibitor Ouabain and ATP1A3 knockdown. We recorded an embryonic trans-neural-epithelial potential generating EF whose pharmacological and surgical manipulation mimicked ATP1A3 knock-down-induced altered DIN axon pathfinding. Using DINs transplantation paradigm, we found that ATP1A3 is required cell-autonomously for EF-mediated long-range guidance. Finally, dominant-negative ATP1A3 mutation causing an early ATP1A3 childhood disease disrupts this fundamental developmental process, revealing unexpected pathogenic mechanisms.

developmental biology↗

bioRxiv2023

Cannabinoid receptor type 2 expression in mouse brain: from mapping to regulation in microglia under inflammatory conditions

Since its detection in the brain, the cannabinoid receptor type 2 (CB2) has been deemed a promising therapeutic target for various neurological and psychiatric disorders. However, precise brain mapping of CB2 expression is currently lacking. Using magnetic cell sorting, calibrated reverse transcription-quantitative PCR, and single-nucleus RNA-seq, we revealed the low level of CB2 expression in all brain regions examined, mainly by a few microglial cells and by neurons in an even lower proportion. Upon lipopolysaccharide stimulation to simulate non-sterile neuroinflammatory conditions, we demonstrated that the inflammatory response was associated with a transient reduction in CB2 mRNA levels in the brain tissue, particularly in microglia. This result, confirmed in the BV2 microglial cells, contrasts with the positive correlation observed between CB2 mRNA levels and the inflammatory response upon stimulation by interferon-gamma, which models sterile inflammatory conditions. Thus, discrete brain CB2 expression may be upregulated or downregulated depending on the inflammatory context.

neuroscience↗

bioRxiv2022

Single cell analysis of the dorsal V-SVZ reveals differential quiescence of postnatal pallial and subpallial neural stem cells driven by TGFbeta/BMP-signalling

The ventricular-subventricular zone (V-SVZ) is the largest neurogenic region of the postnatal forebrain, containing neural stem cells (NSCs) that emerge from both the embryonic pallium and subpallium. Despite of this dual origin, glutamatergic neurogenesis declines rapidly after birth, while gabaergic neurogenesis persists throughout life. Here, we performed single-cell RNA-sequencing (scRNA-Seq) of the postnatal dorsal V-SVZ for unravelling the mechanisms leading to pallial lineage germinal activity silencing. We identify cell lineage-specific NSCs primed for the generation of neurons or glial cells, as well as a large population of so far uncharacterized quiescent NSCs (qNSC). Pallial qNSCs enter a state of deep quiescence, characterized by persistent TGFbeta/BMP signalling, reduced transcriptional activity and Hopx expression, whilst in contrast, subpallial qNSCs remain transcriptionally primed for activation. Induction of deep pallial quiescence is paralleled by a rapid blockade of glutamatergic neuron production and differentiation. Finally, manipulation of the TGFbeta/BMP receptor Bmpr1a demonstrate its key role in mediating these effects at early postnatal times. Together, our results highlight a central role of TGFbeta/BMP-signalling in synchronizing quiescence induction and blockade of neuronal differentiation to rapidly silence pallial germinal activity after birth.

neuroscience↗

bioRxiv2020

Primate naive pluripotent stem cells stall in the G1 phase of the cell cycle and differentiate prematurely during embryo colonization

After reprogramming to naive pluripotency, human pluripotent stem cells (PSCs) still exhibit very low ability to make interspecies chimeras. Whether this is because they are inherently devoid of the attributes of chimeric competency or because naive PSCs cannot colonize embryos from distant species remains to be elucidated. Here, we have used different types of mouse, human and rhesus monkey naive PSCs and analyzed their ability to colonize rabbit and cynomolgus monkey embryos. Mouse embryonic stem cells (ESCs) remained mitotically active and efficiently colonized host embryos. In contrast, primate naive PSCs colonized host embryos with much lower efficiency. Unlike mouse ESCs, they slowed DNA replication after dissociation and, after injection into host embryos, they stalled in the G1 phase and differentiated prematurely, regardless of host species. We conclude that human and non-human primate naive PSCs do not efficiently make chimeras because they are inherently unfit to remain mitotically active during colonization.

cell biology↗