Biology subjects

Vaissiere, T.

Publications and source records attributed to Vaissiere, T..

6 recordsLinked to original sources

bioRxiv2026

NREM Oscillations Mediate Synaptic Proteome Remodelling to Support Synapse Stabilisation

Synapses are known to remodel their proteome during sleep. However, the exact mechanisms driving this remodelling and its impact on synaptic function or cognition are not well understood. We combine 24-hour EEG recordings with time-resolved synaptic proteomics in a model of SYNGAP1-Related Disorders to reveal a mechanism by which slow-waves and spindles, two NREM sleep oscillations, mediate the remodelling of the synaptic proteome. Moreover, we uncover that this remodelling promotes synaptic stabilization, which could support sleep-dependent memory consolidation. In contrast, the increase of slow-waves and decrease of spindles found in Syngap1+/- mice would activate molecular pathways involved in synaptic weakening instead of stabilization. This is consistent with the proposed roles of slow-waves and spindles in synaptic downscaling and potentiation, respectively. Here, we provide evidence on how NREM oscillations regulate the synaptic proteome and reveal a pathological mechanism that could be of relevance to all neurodevelopmental disorders coursing with sleep disturbances.

neuroscience↗

bioRxiv2026

Syngap1 Synchronizes Relative Neuronal Maturation Across Cortical Areas to Organize Distributed Functional Networks

Neurodevelopmental disorders are increasingly viewed as disorders of distributed brain networks, yet how developmental perturbations generate co-occurring hypo- and hyper-functional network states remains unclear. We show that Syngap1 haploinsufficiency in mice produces opposing cortical activity patterns: sensory-evoked responses exhibit reduced gain, whereas state-linked movement/arousal activity is amplified. Restricting Syngap1 deficiency to developing cortical excitatory neurons reproduces distributed sensory hypofunction but not movement-linked hyperfunction, indicating non-uniform, cell-type-dependent contributions to these patterns. During a postnatal window of circuit assembly, Layer 2/3 intratelencephalic populations across cortical regions occupy distinct maturation states, reflected in separable dendritic architectures and intrinsic excitability. Perturbing Syngap1 reduces this developmental separability through region-dependent, opposite-direction effects on dendritic maturation and inversion of ERK-sensitive control of intrinsic excitability. We propose that coordinated relative maturation of interacting neuronal populations establishes distributed network balance, and that gene-dependent shifts in this coordination produce stable, opposing network states.

neuroscience↗

bioRxiv2023

Sensorimotor Integration Supporting Perception Requires Syngap1 Expression in Cortex

Perception, a cognitive construct, emerges through sensorimotor integration (SMI). The genetic mechanisms that shape SMI required for perception are unknown. Here, we demonstrate in mice that expression of the autism/intellectual disability gene, Syngap1, in cortical excitatory neurons is required for formation of somatomotor networks that promote SMI-mediated perception. Cortical Syngap1 expression was necessary and sufficient for setting tactile sensitivity, sustaining tactile object exploration, and promoting tactile learning. Mice with deficient Syngap1 expression exhibited impaired neural dynamics induced by exploratory touches within a cortical-thalamic network known to promote attention and perception. Disrupted neuronal dynamics were associated with circuit-specific long-range synaptic connectivity abnormalities. Our data support a model where autonomous Syngap1 expression in cortical excitatory neurons promotes cognitive abilities through assembly of circuits that integrate temporally-overlapping sensory and motor signals, a process that promotes perception and attention. These data provide systems-level insights into the robust association between Syngap1 expression and cognitive ability.

neuroscience↗

bioRxiv2020

Syngap1 Dynamically Regulates the Fine-Scale Reorganization of Cortical Circuits in Response to Sensory Experience

Experience induces complex, neuron-specific changes in population activity within sensory cortex circuits. However, the mechanisms that enable neuron-specific changes within cortical populations remain unclear. To explore the idea that synapse strengthening is involved, we studied fine-scale cortical plasticity in Syngap1 mice, a neurodevelopmental disorder model useful for linking synapse biology to circuit functions. Repeated functional imaging of the same L2/3 somatosensory cortex neurons during single whisker experience revealed that Syngap1 selectively regulated the plasticity of a low-active, or "silent", neuronal subpopulation. Syngap1 also regulated spike-timing-dependent synaptic potentiation and experience-mediated in vivo synapse bouton formation, but not synaptic depression or bouton elimination in L2/3. Adult re-expression of Syngap1 restored plasticity of "silent" neurons, demonstrating that this gene controls dynamic cellular processes required for population-specific changes to cortical circuits during experience. These findings suggest that abnormal experience-dependent redistribution of cortical population activity may contribute to the etiology of neurodevelopmental disorders.

neuroscience↗

bioRxiv2020

A Simple and Robust Cell Based Assay for the Discovery of Novel Cytokinesis Inhibitors

Cytokinesis is the last step of mitotic cell division that separates the cytoplasm of dividing cells. Small molecule inhibitors targeting either the elements of the regulatory pathways controlling cytokinesis, or the terminal effectors have been of interest as potential drug candidates for the treatment of various diseases. Here we have developed a cell-based assay for the discovery of novel cytokinesis inhibitors. The assay is performed in a 96-well plate format in 48 hours. Living cells, nuclei and nuclei of dead cells are revealed by a single staining step with three fluorescent dyes, followed by live cell imaging using an automated fluorescence microscope. The primary signal is the nuclei-to-cell ratio (NCR). In the presence of cytokinesis inhibitors, this ratio is expected to increase over time, as the ratio of multinucleated cells increases in the population. Cytotoxicity is quantified as the ratio of dead nuclei to total nuclei. A screening window coefficient (Z) of 0.65 indicates that the assay is suitable for screening purposes, as the positive and negative controls are well-separated. EC50 values for four compounds can be reliably determined in a single 96-well plate by using only six different compound concentrations. An excellent test-retest reliability (R2=0.998) was found for EC50 values covering a [~]1500-fold range of potencies. The robustness, simplicity and flexibility of the assay is demonstrated here by using modulators of actin dynamics with different mechanisms of action (jasplakinolide, cytochalasin D and swinholide A) and derivatives of the nonmuscle myosin II inhibitor blebbistatin.

cell biology↗

bioRxiv2018

Re-expression of SynGAP Protein in Adulthood Improves Translatable Measures of Brain Function and Behavior in a Model of Neurodevelopmental Disorders

BackgroundNeurodevelopmental disorder (NDD) risk genes have pleiotropic biological functions, such as control over both developmental and non-developmental processes that influence disease-related phenotypes. Currently, it remains unclear how developmental versus non-developmental processes influence the duration and/or effectiveness of permissive treatment windows for NDDs. SYNGAP1 haploinsufficiency causes an NDD defined by autistic traits, cognitive impairment, and epilepsy. Syngap1 heterozygosity in mice disrupts a developmental critical period, and, consistent with this, certain behavioral abnormalities are resistant to gene therapy initiated in adulthood. However, the Syngap1 endophenotype is extensive and this protein has diverse cell biological functions. Therefore, SynGAP pleiotropy may influence the permissive treatment window for previously untested disease-relevant phenotypes.\n\nMethodsA whole-body gene restoration technique was used to determine how restoration of SynGAP protein in adult heterozygous mice impacted previously untested phenotypes, such as memory, seizure susceptibility, systems-level cortical hyperexcitability, and hippocampal oscillations linked to mnemonic processes.\n\nResultsAdult restoration of SynGAP protein in haploinsufficient mice reversed long-term contextual memory deficits and behavioral measures of seizure susceptibility. Moreover, SynGAP re-expression in adult mice eliminated brain state-dependent, patient-linked paroxysmal interictal spiking and increased the amplitude of hippocampal theta oscillations.\n\nConclusionsSynGAP protein in the mature brain dynamically regulates neural circuit function and influences disease-relevant phenotypes. The impact of these findings is that treatments targeting certain debilitating aspects of SYNGAP1-related disorders may be effective throughout life. Moreover, the efficacy of experimental treatments for SYNGAP1 patients may be quantifiable through changes in species-conserved, state-dependent pathological electroencephalogram signals.

neuroscience↗