Biology subjects

Breton, L.

Publications and source records attributed to Breton, L..

5 recordsLinked to original sources

bioRxiv2025

Seed structure and phosphorylation in the fuzzy coat impact tau seeding competency

Tau is a pathogenic protein in Alzheimers (AD) and other neurodegenerative diseases. The misfolding of tau into {beta}-sheet rich elongated filaments is thought to be a key event in disease pathogenesis, followed by subsequent templated recruitment of monomeric tau into this pathogenic form. Cryo-electron microscopy has revealed that specific tau conformations characterize different diseases. In this study, we explored how tau filament core structure and post-translational modifications in its disordered fuzzy coat influence its seeding capacity in primary neurons and mice. We show that the structure of the seeds affects seeding capacity, but that the AD tau core structure alone is insufficient to capture the full seeding capacity of AD tau. Proteolytic cleavage of AD tau which removes the fuzzy coat causes a loss in seeding capacity, as does removal of phosphorylation from the fuzzy coat by phosphatase treatment. Re-phosphorylation of phosphatase-treated AD tau by kinase treatment partially restores seeding activity. Finally, we find that filaments of recombinant tau with twelve phospho-mimetic residues (PAD12 tau) with the AD fold are able to recapitulate the seeding capacity of AD tau. Combined, these results suggest that the structure of the ordered core, together with phosphorylation in the fuzzy coat, confers the seeding capacity of tau filaments.

neuroscience↗

bioRxiv2024

Network analysis of α-synuclein pathology progression reveals p21-activated kinases as regulators of vulnerability

-Synuclein misfolding and progressive accumulation drive a pathogenic process in Parkinson's disease, yet many brain regions develop more or less pathology than would be predicted by connectivity alone, indicating that intrinsic biological factors influence regional vulnerability. Here, we combined whole brain mapping of -synuclein pathology in wildtype mice 3 days to 9 months after seeding with network diffusion modeling based on anatomical connectivity to derive quantitative measures of regional vulnerability. To identify molecular drivers of this vulnerability, we generated a brain-wide sPAtial Neuron Gene Expression Atlas (PANGEA) and compared regional transcriptional profiles with model-derived vulnerability scores. Vulnerable regions were enriched for specific cellular programs. Specific kinases were also enriched in vulnerable regions, leading to the identification of group II p21-activated kinases (PAKs) as candidate regulators of -synucleinopathy. Pharmacological inhibition of group II PAKs reduced -synuclein aggregation and protected against neuron loss in primary neurons, remained effective when administered after pathology initiation, and suppressed pathology in vivo. Consistent with these findings, genetic depletion of PAK5/6 also suppressed -synuclein aggregation. Together, these results establish a framework linking network-level measures to cellular mechanisms of selective vulnerability and nominate group II PAKs as promising disease-modifying therapeutic targets for Parkinson's disease.

neuroscience↗

bioRxiv2023

Spatial transcriptomics reveals molecular dysfunction associated with Lewy pathology

Lewy pathology composed of -synuclein is the key pathological hallmark of Parkinsons disease (PD), found both in dopaminergic neurons that control motor function, and throughout cortical regions that control cognitive function. Recent work has investigated which dopaminergic neurons are most susceptible to death, but little is known about which neurons are vulnerable to developing Lewy pathology and what molecular changes an aggregate induces. In the current study, we use spatial transcriptomics to selectively capture whole transcriptome signatures from cortical neurons with Lewy pathology compared to those without pathology in the same brains. We find, both in PD and in a mouse model of PD, that there are specific classes of excitatory neurons that are vulnerable to developing Lewy pathology in the cortex. Further, we identify conserved gene expression changes in aggregate-bearing neurons that we designate the Lewy-associated molecular dysfunction from aggregates (LAMDA) signature. This gene signature indicates that neurons with aggregates downregulate synaptic, mitochondrial, ubiquitin-proteasome, endo-lysosomal, and cytoskeletal genes and upregulate DNA repair and complement/cytokine genes. However, beyond DNA repair gene upregulation, we find that neurons also activate apoptotic pathways, suggesting that if DNA repair fails, neurons undergo programmed cell death. Our results identify neurons vulnerable to Lewy pathology in the PD cortex and identify a conserved signature of molecular dysfunction in both mice and humans.

neuroscience↗

bioRxiv2021

Oligomeric α-Synuclein induces skin degeneration in a reconstructed human epidermis model

Cell senescence may promote epidermal inflammation and degeneration, termed as inflammaging, which is accompanied by keratinocyte loss, resulting in fine lines of wrinkles. Recent findings showed that healthy elderly skin expresses age- and neuron-related amyloidogenic proteins, such as tau, {beta}-Amyloid34, and -synuclein (-Syn), typically found in patients with neurodegenerative diseases. These proteins form toxic aggregates that trigger inflammatory signals. Herein, we investigated the impact of oligomeric -Syn (O-Syn) on the neurosphere (NP) and the reconstructed human epidermis (RHE) 3D models. First, we found the expression of -Syn, {beta}-Amyloid, and amyloid precursor protein (APP) in the RHE. Second, we challenged the RHE and NP with O-Syn, which decreased RHE regeneration, measured by the percentage of cell proliferation and thickness of the stratum basale, but did not affect NP neurite outgrowth. O-Syn did not decrease the number of human neonatal epidermal keratinocytes (HEKn) but, as seen for the RHE, it also decreased the proliferation of HEKn. We confirmed that the oligomeric, and not the monomeric -Syn species, accounted for the proliferation-decreasing effect. O-Syn also increased the NF-kB nuclear translocation in HEKn analyzed by nucleus/cytoplasm NF-{kappa}B fluorescence intensity. In addition, O-Syn triggered inflammation in the RHE, by increasing the mRNA levels of IL-1{beta} and tumor necrosis factor-alpha (TNF-), and the release of TNF- in a time-dependent manner. These findings show that O-Syn does not affect neurite outgrowth but induces a decrease in keratinocyte proliferation along with epidermal inflammation. With our tridimensional models, we demonstrated that the neurodegenerative protein O-Syn also degenerates the epidermis, drawing attention to the need of target-based screening to prevent and treat the effects of skin aging.

neuroscience↗

bioRxiv2018

Generation Of iPSC-Derived Human Peripheral Sensory Neurons Releasing Substance P Elicited By TRPV1 Agonists

Neural crest stem cells (NCPCs) have been shown to differentiate into various cell types and tissues during embryonic development, including sensory neurons. The few studies addressing the generation of NCPCs and peripheral sensory neurons (PSNs) from human induced Pluripotent Stem Cells (hiPSCs), generated sensory cells without displaying robust activity. Here, we describe an efficient strategy for hiPSCs differentiation into NCPCs and functional PSNs using chemically defined media and factors to achieve efficient differentiation, confirmed by the expression of specific markers. After 10 days hiPSCs differentiated into NCPCs, cells were then maintained in neural induction medium containing defined growth factors for PSNs differentiation, followed by 10 days in neonatal human epidermal keratinocytes-(HEKn-) conditioned medium. We observed a further increase in PSN markers expression and neurites length after conditioned medium treatment. The resulting neurons released substance P (SP) in response to nociceptive agents such as anandamide and resiniferatoxin. Anandamide induced substance P release via activation of TRPV1 and not CB1. Transcriptomic analysis of the PSNs revealed the main dorsal root ganglia (DRG) neuronal markers and a transcriptional profile compatible with C-LTMR. TRPV1 was detected by immunofluorescence and RNA-Seq in multiple experiments. In conclusion, the developed strategy generated PSNs useful for drug screening that could be applied to patient-derived hiPSCs, consisting in a powerful tool to model human diseases in vitro.

neuroscience↗