Biology subjects

Livesey, F.

Publications and source records attributed to Livesey, F..

4 recordsLinked to original sources

bioRxiv2026

Extracellular matrix defects destabilise apical cytoarchitecture and mechanical properties during early Down syndrome neurodevelopment

Down syndrome (DS) is associated with altered brain development, especially in the cerebellum. However, how trisomy 21 (TS21) is linked to cerebellar defects remains poorly understood. Cerebellar organoids reveal that TS21 leads to extracellular matrix (ECM) alterations, perturbing downstream pathways linked to reduction of apical RAB11+ endosomes. These changes lead to impaired apical maintenance and altered progenitor composition. Significantly, ECM-enriched culture rescues apical defects in TS21 organoids, supporting a functional role for ECM in preserving apical organisation and progenitor niche integrity. In the developing human DS cerebellum and 2D neural cultures, where exogenous ECM is present, severe epithelial disorganisation is attenuated. Nevertheless, ECM organisation and mechanical properties remain altered in 2D cultures. Our findings identify TS21-driven ECM abnormalities as a mechanism impairing apical integrity, progenitor composition and mechanical proprieties in neural stem cell models of DS. Altogether, we established apical maintenance instability as an early developmental defect contributing for DS neuropathology.

Developmental Biology↗

bioRxiv2025

Lysosomal stress induces amyloid-β aggregate release and reactive transformation in human astrocytes

Astrocytes are essential for brain homeostasis and are involved in amyloid-{beta} (A{beta}) clearance, but whether they can produce and release A{beta} aggregates remains unclear. Using human iPSC-derived astrocytes, we show that astrocytes cell autonomously generate small, diffusible A{beta} aggregates under baseline conditions. By combining ultrasensitive single-molecule imaging (DNA-PAINT) and immunoassays, we detect intracellular aggregates and their release into the media. Notably, lysosomal membrane damage induced by L-leucyl-L-leucine methyl ester (LLOMe) significantly increases A{beta} aggregate secretion without altering their size or morphology. Transcriptomic analysis and cytokine profiling reveal that lysosomal stress triggers a reactive astrocyte phenotype marked by upregulation of inflammatory genes and secreted cytokines. These findings suggest that astrocytes are not merely passive A{beta} scavengers but can actively contribute to extracellular A{beta} accumulation under lysosomal stress. Our study highlights astrocytes as active players in Alzheimers disease pathology.

neuroscience↗

bioRxiv2024

Targeting the acetyltransferase NAT10 corrects pathologies in human frontotemporal neurons and extends lifespan in an in vivo Drosophila tauopathy model

Disruption of the neuronal nuclear membrane and perturbation of nucleocytoplasmic transport are features of neurodegenerative diseases, including Alzheimers disease, that involve the microtubule-associated protein tau (MAPT). We previously identified that missense and splicing mutations in the MAPT gene, causal for frontotemporal dementia, result in nuclear envelope deformation and disrupted nucleocytoplasmic transport in human neurons. This is most likely due to microtubule mechanical stress, similar to that observed in Hutchinson-Gilford Progeria Syndrome (HGPS). A small molecule inhibitor of the acetyltransferase NAT10 has been shown to correct nuclear membrane defects in HGPS by modulating microtubule dynamics. We report here that NAT10 inhibition alters microtubule dynamics and corrects nuclear lamina defects and aberrant nucleocytoplasmic transport in human iPSC-derived FTD-MAPT neurons. Similarly, NAT10 inhibition and haploinsufficiency correct neuronal nuclear shape defects and extend lifespan in vivo in a Drosophila model of tauopathy. Our results show that NAT10 mediates neuronal pathologies in tauopathies and is a promising new therapeutic target in these diseases.

neuroscience↗

bioRxiv2017

Extracellular monomeric and aggregated tau efficiently enter human neurons through overlapping but distinct pathways

A current working model is that Alzheimer's disease actively spreads from diseased to healthy neurons, mediated by transfer of extracellular, abnormal, disease-specific forms of the microtubule-associated protein tau. It is currently unclear whether transfer of tau between neurons is a toxic gain-of-function process in dementia, or reflects a constitutive biological process. We report two mechanisms of entry of monomeric tau to neurons: a rapid early dynamin-dependent phase, and a second, slower actin-dependent phase, suggesting that monomeric tau enters neurons via rapid saturable clathrin-mediated endocytosis and also by bulk endocytosis. Aggregated tau entry is independent of actin polymerisation and largely dynamin dependent, consistent with clathrin-mediated endocytosis and distinct from macropinocytosis, the major route for aggregated tau entry reported for non-neuronal cells. Anti-tau antibodies abrogate tau entry into neurons, with tau carrying antibody with it into neurons, indicating that antibody binding is insufficient to prevent neuronal tau entry.

neuroscience↗