Biology subjects

Pascual, O.

Publications and source records attributed to Pascual, O..

3 recordsLinked to original sources

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↗