Biology subjects

Pascual, O.

Publications and source records attributed to Pascual, O..

5 recordsLinked to original sources

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

MorphoCellSorter: An Andrews plot-based sorting approach to rank microglia according to their morphological features

Microglia exhibit diverse morphologies reflecting environmental conditions, maturity or functional states. Thus, morphological characterization provides important information to understand microglial roles and functions. Most recent morphological analysis relies on classifying cells based on morphological parameters. However, this classification may lack biological relevance, as microglial morphologies represent a continuum rather than distinct, separate groups, and do not correspond to mathematically defined, clusters irrelevant of microglial cells function. Instead, we propose a new open-source tool, MorphoCellSorter, which assesses microglial morphology by automatically computing morphological criteria, using principal component analysis and Andrews plots to rank cells. MorphoCellSorter properly ranked cells from various microglia datasets in mice and rats of different age, from in vivo, in vitro and ex vivo models, that were acquired using diverse imaging techniques. This approach allowed for the discrimination of cell populations in various pathophysiological conditions. Finally, MorphoCellSorter offers a versatile, easy and ready-to-use method to evaluate microglial morphological diversity that could easily be generalized to standardize practices across laboratories.

neuroscience↗

bioRxiv2024

The HUSH epigenetic repressor complex silences PML nuclear bodies-associated HSV-1 quiescent genomes

Herpes simplex virus 1 (HSV-1) latently infected neurons show multiple patterns in the distribution of the viral genomes within the nucleus, at least in mouse models. One of the major patterns is characterized by the presence of quiescent HSV-1 genomes trapped in promyelocytic leukemia nuclear bodies (PML NBs) to form viral DNA-containing PML-NBs (vDCP NBs). Using a cellular model reproducing the formation of vDCP NBs we previously showed that viral genomes are chromatinized with the H3.3 histone variant modified on its lysine 9 by tri-methylation (H3.3K9me3) a chromatin mark associated with transcriptional repression. Here we identify an essential role for the HUSH complex and its SETDB1 and MORC2 effectors in the acquisition of the H3K9me3 mark on the PML NBs-associated HSV-1 and in the maintenance of HSV-1 transcriptional repression. ChiP-seq analyses highlight the association of the H3K9me3 mark with the entire viral genome. Inactivating the HUSH-SETDB1-MORC2 repressor complex prior to viral infection results in a significant reduction of H3K9me3 on the viral genome, while the overall impact on the cellular genome is minimal, except for expected changes in families of LINE1 retroelements. Depletion of HUSH, SETDB1, or MORC2, relieves the repressive state of HSV-1 in infected primary human fibroblasts as well as human induced pluripotent stem cell-derived sensory neurons (hiPSDN). We discovered that the viral protein ICP0 induces MORC2 degradation via the proteasome machinery. This process is concurrent with ICP0 and MORC2 depletion capability to reactivate silenced HSV-1 in hiPSDN. Overall, our findings underscore the robust antiviral function of the HUSH-SETDB1-MORC2 repressor complex against a herpesvirus by modulating chromatin marks linked to repression, thus presenting promising avenues for novel anti-herpesvirus therapeutic strategies. Significance statementHerpes simplex virus 1 (HSV-1) is a major human pathogen, which remains latent in the trigeminal ganglia (TG) neurons of the infected individuals. Its reactivation is characterized by a variety of clinical symptoms the most severe ones being keratitis and herpesvirus encephalitis. The colonization of the CNS by the virus during the individual life is a well-known fact but the pathophysiological effects on neurons homeostasis are still underestimated. It is thus paramount to understand the molecular mechanisms that control HSV-1 latency and maintain the virus in a pseudo silent state.

microbiology↗

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↗

bioRxiv2022

Microglia shape the embryonic development of mammalian respiratory networks

Microglia, brain-resident macrophages, play key roles during prenatal development in defining neural circuitry function, including ensuring proper synaptic wiring and maintaining homeostasis. Mammalian breathing rhythmogenesis arises from interacting brainstem neural networks that are assembled during embryonic development, but the specific role of microglia in this process remains unknown. Here, we investigated the anatomical and functional consequences of respiratory circuit formation in the absence of microglia. We first established the normal distribution of microglia within the wild-type (WT, Pu.1+/+) mouse brainstem at embryonic ages when the respiratory networks are known to emerge (embryonic day (E) 14.5 for the parafacial respiratory group (epF) and E16.5 for the preBotzinger complex (preBotC)). In transgenic mice depleted of microglia (Pu.1-/- mutant), we performed anatomical staining, calcium imaging and electrophysiological recordings of neuronal activities in vitro to assess the status of these circuits at their respective times of functional emergence. Spontaneous respiratory-related activity recorded from reduced in vitro preparations showed an abnormally slow rhythm frequency expressed by the epF at E14.5, the preBotC at E16.5 and in the phrenic motor nerves from E16.5 onwards. These deficits were associated with a reduced number of active epF neurons, defects in commissural projections that couple the bilateral preBotC half-centers, and an accompanying decrease in their functional coordination. These abnormalities probably contribute to eventual neonatal death, since plethysmography revealed that E18.5 Pu.1-/- embryos are unable to sustain breathing activity ex utero. Our results thus point to a crucial contribution of microglia in the proper establishment of the central respiratory command during embryonic development.

neuroscience↗