Biology subjects

Nguyen-Renou, E.

Publications and source records attributed to Nguyen-Renou, E..

4 recordsLinked to original sources

bioRxiv2025

A high-content imaging workflow to screen for molecules that reduce cellular uptake of α-synuclein preformed fibrils

A classical pathological hallmark of many neurodegenerative diseases is the formation of protein-rich aggregates and inclusions. In Parkinsons disease (PD), -synuclein (-syn) constitutes a major protein component of pathological inclusions, termed Lewy bodies. These -syn aggregates are hypothesized to spread throughout the nervous system by cell-to-cell transmission acting as templates to amplify aggregate formation. In vitro generated -syn aggregates, commonly called preformed fibrils (PFFs), have been used to investigate a number of aspects related to -syn mediated pathology across different model systems. Here we describe a semi-automated assay to screen for small molecules that interfere with the cellular uptake and accumulation of PFFs. The assay uses dopaminergic progenitor cells (DPCs), derived from human induced pluripotent stem cells (hiPSCs). In an initial screen, we tested 1520 small molecules and identified several molecules that strongly reduce intracellular PFF load in DPCs. From these hits, candidate compounds were validated in dopaminergic neurons (DNs) to demonstrate the utility of the assay. This assay provides a robust, scalable and adaptable tool to screen for molecules that affect PFF uptake in hiPSC-derived cell models. Within the scope of this screen, it led to the identification of a set of compounds with diverse annotated targets that effectively reduce the uptake of synuclein aggregates in DPCs and DNs.

neuroscience↗

bioRxiv2025

An automated workflow for quantifying the formation of synuclein aggregates in human dopaminergic neurons

Parkinsons disease (PD) is a neurodegenerative disorder characterized by alpha-synuclein (-syn) aggregates termed Lewy bodies. To model PD pathology in vitro, preformed fibrils of -syn (PFFs), which can be taken up by cells, provide a seed that drives misfolding and aggregation of endogenous -syn, with new aggregates amplifying this process. External application of PFFs to dopaminergic neurons (DNs) increases aggregate formation, marked by -syn phosphorylation at serine 129 (pS129-syn), a pathological PD marker. Building on this, we developed an automated synuclein seeding assay to quantify new -syn aggregates in iPSC-derived DNs. Using pS129-syn as a readout, we show that PFFs elicit a time- and dose-dependent increase in pS129-syn aggregates. Our high-throughput assay further revealed that aggregate formation depends on endogenous -syn levels. Treatment with PFFs produced a greater increase in pS129-syn aggregates in iPSC DNs derived from a PD patient with a triplication in the SNCA gene, which encodes the -syn protein and which elevates total -syn levels, relative to DNs from an isogenic iPSC line from the same individual, in which the SNCA gene mutation had been corrected by CRISPR/Cas9. In contrast, no pS129-syn signal was detected in neurons in which all copies of the SNCA gene had been knocked out (KO). This high-content imaging assay for synuclein seeding offers a platform for assessing compounds and therapeutics that may impede -syn aggregate formation.

neuroscience↗

bioRxiv2023

A deep learning convolutional neural network distinguishes neuronal models of Parkinson's disease from matched controls

Parkinsons disease (PD) is a neurodegenerative disorder that results in the loss of dopaminergic neurons in the substantia nigra pars compacta. Despite advances in understanding PD, there is a critical need for novel therapeutics that can slow or halt its progression. Induced pluripotent stem cell (iPSC)-derived dopaminergic neurons have been used to model PD but measuring differences between PD and control cells in a robust, reproducible, and scalable manner remains a challenge. In this study, we developed a binary classifier convolutional neural network (CNN) to accurately classify microscopy images of PD models and matched control cells. We acquired images of iPSC-derived neural precursor cells (NPCs) and dopaminergic (DANs) and trained multiple CNN models comparing control cells to genetic and chemical models of PD. Our CNN accurately predicted whether control NPC cells were treated with the PD-inducing pesticide rotenone with 97.60% accuracy. We also compared control to a genetic model of PD (deletion of the Parkin gene) and found a predictive accuracy of 86.77% and 95.47% for NPC and DAN CNNs, respectively. Our cells were stained for nuclei, mitochondria, and plasma membrane, and we compared the contribution of each to the CNNs accuracy. Using all three features together produced the best accuracy, but nuclear staining alone produced a highly predictive CNN. Our study demonstrates the power of deep learning and computer vision for analyzing complex PD-related phenotypes in DANs and suggests that these tools hold promise for identifying new targets for therapy and improving our understanding of PD.

neuroscience↗

bioRxiv2023

A dual hit of α-synuclein internalization and immune challenge leads to formation and maintenance of Lewy body-like inclusions in human dopaminergic neurons

Lewy bodies (LBs), rich in -synuclein, are a hallmark of Parkinsons disease (PD). Understanding their biogenesis is likely to provide insight into the pathophysiology of PD, yet a cellular model for LB formation remains elusive. The realization that the immune challenge is a trigger for neurodegenerative diseases has been a breakthrough in the understanding of PD. Here, iPSC-derived human dopaminergic (DA) neurons from multiple healthy donors were found to form LB-like inclusions following treatment with - synuclein preformed fibrils, but only when coupled to an immune challenge (interferon-gamma or interleukin-1 beta) or when co-cultured with activated microglia. Human cortical neurons derived from the same iPSC lines did not form LB-like inclusions. Exposure to interferon-gamma impairs autophagy in a lysosomal-specific manner in vitro, similar to the disruption of proteostasis pathways that contribute to PD. We find that lysosomal membrane proteins LAMP1 and LAMP2 and transcription factors regulating lysosomal biogenesis and function are downregulated in DA but not cortical neurons. Finally, due to the excellent sample preservation afforded by cells compared to post-mortem PD brain tissue, we conclude that the LB-like inclusions in DA neurons are membrane-bound, suggesting they are not limited to the cytoplasmic compartment. In Brief O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=170 SRC="FIGDIR/small/542776v3_figabs.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@1f41855org.highwire.dtl.DTLVardef@69798dorg.highwire.dtl.DTLVardef@ab55bdorg.highwire.dtl.DTLVardef@8a16b8_HPS_FORMAT_FIGEXP M_FIG C_FIG Bayati et al. identify that iPSC-derived dopaminergic neurons undergoing a dual hit treatment of exogenous -synuclein fibrils and proinflammatory cytokines form Lewy body-like inclusions. The dual hit treatment also led to the downregulation of lysosomal proteins. Characterization of inclusions revealed that inclusions were membrane-bound and LC3B-positive, suggesting they are dysfunctional autophagosomes. HighlightsO_LI-synuclein preformed fibril administration coupled with Interferon-gamma exposure leads dopaminergic neurons to form Lewy body-like inclusions C_LIO_LIInclusions are filamentous, membranous, and filled with aberrant organelles C_LIO_LIImpaired autophagic flux and downregulation of TFEB, NRF2, LAMP1, and LAMP2 correlated with inclusion formation C_LIO_LIActivation of NRF2 through the treatment of neurons with the antioxidant perillaldehyde, prevents inclusion formation C_LI

neuroscience↗