Biology subjects

Dehorter, N.

Publications and source records attributed to Dehorter, N..

9 recordsLinked to original sources

bioRxiv2026

Serotonergic circuit architecture underlies sex dimorphism in anxiogenic states

The serotonergic system underpins anxiety-like behavior vital for the adaptive response to a new environment. However, our understanding of the neural circuitry underlying the diversity of anxiety-like behaviors across individuals is limited. Whilst previous studies have characterized diverse features related to the neurochemical substrate of serotonergic neurotransmission and behavioral presentation between males and females, no investigations have fully addressed the sexual dimorphism in the structural and functional connectivity of serotonergic circuits. Here, using functional FosTRAP connectivity analysis, we found sex-dependent functional differences in the serotonergic neurons of the dorsal raphe nucleus (DRN), such as enriched connectivity to the amygdala in females, compared to male mice. We also discovered previously unidentified morpho-functional sex-specific differences in DRN serotonergic circuitry that reflects the disparity in behavior presentation. To understand the molecular basis of serotonergic circuit architecture differences between sexes, we leveraged on single-cell RNA sequencing dataset from DRN serotonergic cells taking sex as a biological variable and spotted some gene candidates involved in neural circuit wiring. Altering the expression of the receptor tyrosine kinase Erbb4 in serotonergic circuits, altered the axonal connectivity to downstream targets and shifted sex-specific behavior which. Overall, this study provides an essential foundation to delineate the molecular basis and connectivity pattern mechanisms underlying the serotonergic system-dependent sex-specific behaviors. Since alterations in serotonin function play a vital role in adaptive behavior, as well as various pathologies including chronic anxiety and depression, this study may advance our understanding of sex-biases in presentation and treatment response of neuropsychiatric disorders.

neuroscience↗

bioRxiv2025

Spatially precise neuron formation via hydrogel mediated modulation of the host astrocyte response

The regenerative capacity of the central nervous system after injury or disease is limited. Advancements in genetic and epigenetic reprogramming of non-neuronal cells into induced neurons presents a promising strategy for neuronal replacement and circuit reconstruction yet is hindered by suboptimal reprogramming efficacy. Here, we have achieved high astrocyte-to-neuron reprogramming efficacy through the ectopic expression of a SOX2 transcription factor using adeno-associated viral vectors. We subsequently designed a hybrid composite biomaterial to act as an implantable reprogramming workshop that perform sequential operations. Once injected, this bespoke system forms a tissue mimetic hydrogel encouraging the ingress of astrocytes to act as our raw material. We demonstrate that the system localized and enhanced the spatially confined delivery of reprogramming factors, entrapping astrocytes to then pass through an intermediate neuroblast state to robustly yield mature neurons. Sustained delivery of valproic acid within the system further promoted neuronal maturation. Overall, using design rules informed by requirements of the reprogramming strategy, we have designed a smart delivery system optimized for both the target tissue and reprogramming factors in a minimally invasive manner to enhance neural repair. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=163 HEIGHT=200 SRC="FIGDIR/small/695501v1_ufig1.gif" ALT="Figure 1"> View larger version (65K): org.highwire.dtl.DTLVardef@397e41org.highwire.dtl.DTLVardef@90047forg.highwire.dtl.DTLVardef@1175831org.highwire.dtl.DTLVardef@19f30eb_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

Tau controls NMDA receptor trafficking during homeostatic synaptic plasticity

Homeostatic synaptic plasticity is essential for maintaining stable neural circuit function by preventing excessive neuronal excitation or inhibition. Chronic perturbation of neuronal activity triggers a compensatory modulation of the number of -amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and N-methyl-D-aspartate (NMDA) glutamate receptors at the excitatory synapses. Previous research has primarily focused on AMPA receptors, yet the molecular mechanisms regulating the trafficking of NMDA receptors during homeostatic synaptic scaling remain unclear. Here we identify the microtubule-associated protein Tau as an essential molecule that mediates the synaptic upscaling of GluN2B-containing NMDA receptors during prolonged synaptic inactivity. Chronic activity blockade increases Tau phosphorylation at Ser-235 by cyclin-dependent kinase 5 (Cdk5), enhancing its interaction with and retention of active Fyn tyrosine kinase in the postsynaptic compartment. This promotes the phosphorylation of GluN2B at Tyr-1472, subsequently stabilising the expression of NMDA receptors on the neuronal plasma membrane. Finally, we showed that Tau pathology and disease-associated mutations in Tau and the GluN2B carboxyl-terminal tail disrupt the homeostatic synaptic upscaling of NMDA receptors following chronic neuronal silencing. Together, our findings identify a physiological role for Tau in homeostatic synaptic plasticity, the perturbation of which can lead to neuronal hyperexcitation, seizures and excitotoxic cell death.

neuroscience↗

bioRxiv2024

Maladaptation of Memory Systems Impairs Dorsal CA1-Dependent Temporal Binding and Declarative Memory in The Cntnap2 Knockout Mouse Model of Autism

Growing evidence implicates the hippocampus in the pathophysiology of autism spectrum disorder, particularly in the domains of social interactions and cognition. Yet, the mechanisms driving hippocampal-dependent cognitive atypicalities in autism remain poorly defined. Here, we characterized how dysfunction of the CA1 subfield of the dorsal hippocampus drives critical components of declarative memory. Using trace fear conditioning in the Cntnap2 knockout mouse model of autism, we found that capabilities to retain the association of temporally distant stimuli (i.e. temporal binding) were reduced relative to wildtype mice. Fiber photometry and optogenetic experiments demonstrated that reduced CA1 activity during temporal gaps underlies this impairment, linking CA1 dysfunction to a deficit of long-term memory retention in autism. Using a relational/declarative memory task, we also revealed a deficit in flexible spatial memory, and a preferential use of egocentric learning strategy. This unflexible learning strategy resulted from the imbalance between memory system activity, promoting frontostriatal-dependent procedural learning instead of dorsal CA1/hippocampus-dependent relational/declarative memory. Overall, this study establishes dorsal CA1 dysfunction as a circuit-level mechanism underlying cognitive inflexibility in autism, providing a neurobiological framework for hippocampal-dependent memory deficits in the condition.

neuroscience↗

bioRxiv2024

Glutamine Transport via Neurotransmitter Transporter 4 (NTT4, SLC6A17) Maintains Presynaptic Glutamate Supply at Excitatory Synapses in the Central Nervous System

The glutamate-glutamine cycle is thought to be the principle metabolic pathway that recycles glutamate at excitatory synapses. In this cycle, synaptically released glutamate is sequestered by astrocytes and converted to glutamine before being returned to the presynaptic terminal for conversion back into glutamate to replenish the neurotransmitter pool. While many aspects of this cycle have been extensively studied, a key component remains unknown: the nature of the transporter responsible for the presynaptic uptake of glutamine. We hypothesise that neurotransmitter transporter 4 (NTT4/SLC6A17) plays this role. Accordingly, we generated NTT4 knockout mice to assess its contribution to presynaptic glutamine transport and synaptic glutamate supply. Using biochemical tracing of [1-13C] glucose and [1,2-13C] acetate in awake mice, we observe a reduction of neuronal glutamate supply when NTT4 is absent. In addition, direct electrical recording of hippocampal mossy fibre boutons reveals a presynaptic glutamine transport current that is entirely inhibited by genetic or pharmacological elimination of NTT4. The role of NTT4 in neurotransmission was demonstrated by electrophysiological recordings in acute hippocampal slices, which reveal that NTT4 is required to maintain vesicular glutamate content and to sustain adequate levels of glutamate supply during periods of high-frequency neuronal activity. Finally, behavioural studies in mice demonstrate a deficit in trace fear conditioning; a hippocampus-dependent memory paradigm, and abnormalities in nest building, anxiety behaviour, and social preference. These results demonstrate that NTT4 is a presynaptic glutamine transporter which is a central component of the glutamate-glutamine cycle. NTT4 and hence the glutamate-glutamine cycle maintain neuronal glutamate supply for excitatory neurotransmission during high-frequency synaptic activity, and are key regulators of memory retention and normal behaviour.

neuroscience↗

bioRxiv2024

Alpha Synuclein Induced Immune Response Triggers Parkinson's Disease Like Symptoms

Increasing evidence suggests that Parkinsons disease is an autoimmune disorder, with findings of elevated peripheral blood mononuclear cell in patients, and antigenic properties of -synuclein driving both the innate and adaptive immunity. Yet, how the interaction of -synuclein and a specific immune response participates to Parkinsons disease ontogenesis has remained unanswered. Here, we reveal that autoimmune response to an -synuclein antigen underlies Parkinsons disease. We demonstrate that autoimmunity mediated by CD4+T cell activation with -synuclein -syn61-75 antigen is required to lead to immune cell infiltration and localized inflammation in the substantia nigra, triggering dopaminergic cell neurodegeneration and deficits in locomotion and gait kinematics. This study offers the first immune-induced mouse model that recapitulates all features of Parkinsons disease to study the mechanisms triggering disease onset. It provides the basis for temporally tracking symptom development, exploring preventive strategies and prodromal therapeutic interventions in Parkinsons Disease. In briefPeripheral -synuclein immunization causes Parkinsons disease-like symptoms in mice. Highlights- Both CD4+ T cells and -synuclein are essential for Parkinsons disease ontogenesis. - Peripheral injection of -syn61-75 induces significant CD4+ T cell infiltration in the mouse brain. - -syn61-75 immunization is associated with inflammation, -synuclein aggregation and dopaminergic cell loss in the substantia nigra pars compacta. - Levodopa-sensitive motor symptoms are detected 8 weeks following -syn61-75 immunization in mice. - This study offers a novel autoimmune -synuclein induced mouse model of Parkinsons disease.

neuroscience↗

bioRxiv2022

Identification of m6A and m5C RNA modifications at single-molecule resolution from Nanopore sequencing

The epitranscriptome embodies many new and largely unexplored functions of RNA. A significant roadblock hindering progress in epitranscriptomics is the identification of more than one modification in individual transcript molecules. We address this with CHEUI (CH3 (methylation) Estimation Using Ionic current). CHEUI predicts N6-methyladenosine (m6A) and 5-methylcytidine (m5C) in individual molecules from the same sample, the stoichiometry at transcript reference sites, and differential methylation between any two conditions. CHEUI processes observed and expected nanopore direct RNA sequencing signals to achieve high single-molecule, transcript-site, and stoichiometry accuracies in multiple tests using synthetic RNA standards and cell line data. CHEUIs capability to identify two modification types in the same sample reveals a co-occurrence of m6A and m5C in individual mRNAs in cell line and tissue transcriptomes. CHEUI provides new avenues to discover and study the function of the epitranscriptome.

bioinformatics↗

bioRxiv2021

Autism Spectrum Disorder is a Risk Factor for PTSD-like Memory Formation

A rising concern in Autism Spectrum Disorder (ASD) is the heightened sensitivity to stress and trauma, the potential consequences of which have been overlooked, particularly upon the severity of the ASD traits. This study investigated the predisposition to, and impact of, Post-Traumatic Stress Disorder (PTSD) in ASD. We first demonstrated a reciprocal relationship between the two disorders and revealed that exposure to a mild stressful event induces PTSD-like memory in four mouse models of ASD. We also establish an unanticipated consequence of stress in this condition, showing that the formation of PTSD-like memory leads to the aggravation of the core traits associated with ASD. Such a susceptibility to developing PTSD-like memory in ASD stemmed from hyperactivation of the prefrontal cortex and altered fine-tuning of parvalbumin interneuron firing. We show that this traumatic memory can be treated by recontextualization, reducing the deleterious effects on the core symptoms of ASD. Overall, this study reveals multi-level neurobiological mechanisms that explain the increased vulnerability to develop PTSD in ASD. It provides a framework for future examination of the impact of PTSD-like memory in autism and offers new directions toward behavioral therapeutic interventions targeting traumatic memory in ASD.

neuroscience↗

bioRxiv2020

Loss of the Er81 Transcription Factor in Cholinergic Cells Alters Striatal Activity and Habit Formation

The finely-tuned activity of cholinergic interneurons (CINs) in the striatum is key for motor control, learning, and habit formation. Yet, the molecular mechanisms that determine their unique functional properties remain poorly explored. Using a combination of genetic and biochemical assays, in vitro and in vivo physiological characterisation, we report that selective ablation of the Er81 transcription factor leads to prominent changes in CIN molecular, morphological and electrophysiological features. In particular, the lack of Er81 amplifies intrinsic delayed-rectifier and hyperpolarization-activated currents, which subsequently alters the tonic and phasic activity of CINs. We further demonstrate that these alterations enhance their pause and time-locked responses to sensorimotor inputs in awake mice. Finally, this study reveals an Er81-dependent developmental mechanism in CINs essential for habit formation in adult mice. Highlights- The Er81 transcription factor is expressed in striatal cholinergic interneurons (CINs) - Conditional deletion of Er81 alters key molecular, morphological and electrophysiological properties of CINs in adult mice - Deletion of Er81 reduces the intrinsic excitability of CINs by upregulating delayed rectifier and hyperpolarization-activated currents - Deletion of Er81 alters in vivo striatal activity and habit formation

neuroscience↗