Biology subjects

Hautbergue, G. M.

Publications and source records attributed to Hautbergue, G. M..

9 recordsLinked to original sources

bioRxiv2026

Astrocyte dysfunction distinguishes monozygotic twin C9orf72 expansion carriers discordant for amyotrophic lateral sclerosis.

Hexanucleotide repeat expansions in C9orf72 are the most common genetic cause of amyotrophic lateral sclerosis, yet many carriers remain asymptomatic for decades or never develop disease. This incomplete penetrance suggests that phenoconversion from genetic susceptibility to symptomatic disease onset is governed by epigenetic, environmental and cell-intrinsic modifiers. Astrocytes are key mediators of non-cell-autonomous neurodegeneration in ALS, but whether they undergo disease-associated phenoconversion in C9orf72 expansion carriers remains unclear. We investigated astrocyte-associated mechanisms of phenoconversion using a unique C9orf72 pedigree comprising monozygotic twins discordant for ALS and their asymptomatic father. This enabled analysis across a continuum from non-penetrance to late-stage neurodegeneration while controlling for inherited genetic background. Notably, the unaffected twin exhibited hypermethylation of the expanded C9orf72 allele, identifying an epigenetic correlate of non-penetrance. To define symptomatic and asymptomatic-associated astrocyte states, fibroblasts from this pedigree were directly reprogrammed into astrocytes and subjected to molecular, functional, electrophysiological and translatome analyses. Astrocytes derived from symptomatic ALS individuals were found to exhibit astrocyte-mediated toxicity towards motor neurons, canonical C9orf72 molecular pathology and connexin-related membrane dysfunction. Specifically, RNA foci and dipeptide repeat protein burden peaked in astrocytes obtained early in disease in the symptomatic twin and declined in astrocytes derived from samples obtained at advanced disease stages, whereas motor neuron toxicity increased progressively, demonstrating a dissociation between aggregate burden and functional neurotoxicity. In contrast, connexin-mediated electrophysiological dysfunction emerged with symptomatic disease and closely tracked with maximal toxicity. Translatome profiling revealed early global translational repression and impaired proteostasis in symptomatic astrocytes, whereas unaffected and non-penetrant C9-carriers retained enrichment of protein homeostasis pathways. These findings define distinct astrocyte states associated with asymptomatic, early symptomatic and late-stage disease. Notably, the affected twin reported substantially higher lifetime strenuous physical activity compared to the unaffected twin, consistent with a potential role for sustained exercise-related stress in accelerating disease onset in genetically susceptible individuals. Experimentally modelling increased stress induced aberrant upregulation of connexin-mediated currents in C9orf72 astrocytes, including in asymptomatic carriers, indicating that physiological stress can unmask latent astrocyte-intrinsic vulnerability and precipitate dysfunction in cellular homeostasis. Together, these findings redefine phenoconversion in C9orf72-associated amyotrophic lateral sclerosis to be associated with a significant upregulation of astrocyte toxicity, failure of resilience and demonstrate that the astrocyte disease state can be potentially induced by external stressors.

neuroscience↗

bioRxiv2025

Comparison of AAV9-driven motor neuron transduction following different CNS-directed delivery methods in mice

AbstractO_ST_ABSBackgroundC_ST_ABSGene therapies are promising for diseases previously considered incurable. Adeno-associated virus serotype 9 (AAV9) demonstrates remarkable tropism for motor neurons (MNs) and represents an exciting candidate to target genetic causes of motor neuron diseases like amyotrophic lateral sclerosis (ALS). However, systemic delivery risks immunogenicity and off-target effects, therefore localised delivery to the CNS is advantageous. New methodWe assessed MN transduction in wild-type mice using AAV9-controlled, cytomegalovirus-promoter driven, enhanced GFP expression. Intra-cisterna magna (ICM) and intra-cerebroventricular (ICV) methods were compared. Four weeks post-delivery, GFP positivity in MN and astrocytes were quantified via immunohistochemical approaches and viral genome copy number determined by qPCR. ResultsAll delivery methods achieved high MN transduction in lumbar spinal cord (>68%). Unilateral ICV delivery provided the highest and most consistent levels (89 {+/-} 3%), and minimal peripheral viral copies. ICV delivery resulted in higher astrocytic transduction, most notably in the cortex. Brainstem MN transduction was high with all methods (>55%). We failed to find evidence of neuronal transduction in motor cortex. Viral genome copies trended higher in spinal cord and brainstem with ICV approaches, however further work is required to understand how bilateral delivery leads to such profound increases. Comparison to existing methodsWhilst several routes of administration into cerebrospinal fluid exist, direct comparisons for targeting MNs in vivo remain limited. ConclusionsOverall, consideration of gene therapy delivery methods is critical to ensure that the most appropriate administration route is chosen to reach MNs effectively, selectively, and at high levels to exact biological effects. HighlightsO_LICSF delivery of AAV9 targets >68% of lumbar spinal cord (SC) motor neurons C_LIO_LIUnilateral ICV yields high and consistent lumbar SC motor neuron transduction (>88%) C_LIO_LIUnilateral ICV results in the lowest number of peripheral viral copies C_LIO_LIICV targets significantly more astrocytes, particularly in cortex C_LIO_LIBilateral ICV leads to significantly higher viral copies in the liver C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=138 SRC="FIGDIR/small/662642v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@bd83a5org.highwire.dtl.DTLVardef@df63aorg.highwire.dtl.DTLVardef@a09142org.highwire.dtl.DTLVardef@1a0887a_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

GRASPS: a simple-to-operate translatome technology reveals omics-hidden disease-associated pathways in TDP-43-related amyotrophic lateral sclerosis

Transcriptomes and translatomes measure genome-wide levels of total and ribosome-associated RNAs. A few hundred translatomes were reported over >250,000 transcriptomes highlighting the challenges of identifying translating RNAs. Here, we used a human isogenic inducible model of TDP-43-linked amyotrophic lateral sclerosis, which exhibits altered expression of thousands of transcripts, as a paradigm for the direct comparison of whole-cell, cytoplasmic and translating RNAs, showing broad uncoupling and poor correlation between disease-altered transcripts. Moreover, based on precipitation of endogenous ribosomes, we developed GRASPS (Genome-wide RNA Analysis of Stalled Protein Synthesis), a simple-to-operate translatome technology. Remarkably, GRASPS identified three times more differentially-expressed transcripts with higher fold changes and statistical significance, providing unprecedented opportunities for data modeling at stringent filtering and discovery of previously omics-missed disease-relevant pathways, which functionally map on dense gene regulatory networks of protein-protein interactions. Based on its simplicity and robustness, GRASPS is widely applicable across disciplines in the biotechnologies and biomedical sciences.

molecular biology↗

bioRxiv2024

RAN translation of C9ORF72-related dipeptide repeat proteins recapitulates hallmarks of motor neurone disease and identifies hypothermia as a therapeutic strategy in zebrafish

ObjectiveHexanucleotide repeat expansions in the C9orf72 gene are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). A large body of evidence implicates DPRs as one of the main drivers of neuronal injury in cell and animal models. MethodsA pure repeat-associated non-AUG (RAN) translation zebrafish model of C9orf72-ALS/FTD was generated. Embryonic and adult transgenic zebrafish lysates were investigated for the presence of RAN-translated DPR species and adult-onset motor deficits. Using C9orf72 cell models as well as embryonic C9orf72-ALS/FTD zebrafish, hypothermic-therapeutic temperature management (TTM) was explored as a potential therapeutic option for C9orf72-ALS/FTD. ResultsHere we describe a pure RAN translation zebrafish model of C9orf72-ALS/FTD that exhibits significant RAN-translated DPR pathology and progressive motor decline. We further demonstrate that hypothermic-TTM results in a profound reduction in DPR species in C9orf72-ALS/FTD cell models as well as embryonic C9orf72-ALS/FTD zebrafish. InterpretationThe transgenic model detailed in this paper provides a medium throughput in vivo research tool to further investigate the role of RAN-translation in C9orf72-ALS/FTD and further understand the mechanisms that underpin neuroprotective strategies. Hypothermic-TTM presents a viable therapeutic avenue to explore in the context of C9orf72-ALS/FTD.

molecular biology↗

bioRxiv2021

C9orf72-derived poly-GA DPRs undergo endocytic uptake in iNPC-derived astrocytes and spread to motor neurons

Dipeptide repeat proteins (DPRs) are aggregation-prone polypeptides encoded by the pathogenic G4C2 repeat expansion in the C9orf72 gene, the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD). In this study, we focus on the role of poly-GA DPRs in disease spread. We demonstrate that recombinant poly-GA oligomers can directly convert into solid-like aggregates and form characteristic &[beta]-sheet fibrils in vitro. To dissect the process of cell-to-cell DPR transmission, we closely follow the fate of poly-GA DPRs in either their oligomeric or fibrillized form after administration in the cell culture medium. We observe that poly-GA DPRs are taken up via dynamin-dependent and - independent endocytosis, eventually converging at the lysosomal compartment and leading to axonal swellings in neurons. We then use a co-culture system to demonstrate astrocyte-to- motor neuron DPR propagation, showing that astrocytes may internalise and release aberrant peptides in disease pathogenesis. Overall, our results shed light on the mechanisms of poly- GA cellular uptake and cell-to-cell propagation, suggesting lysosomal impairment as a possible feature underlying the cellular pathogenicity of these DPR species.

neuroscience↗

bioRxiv2021

The master energy homeostasis regulator PGC-1alpha couples transcriptional co-activation and mRNA nuclear export

PGC-1 plays a central role in maintaining the mitochondrial and energy metabolism homeostasis, linking external stimuli to the transcriptional co-activation of genes involved in adaptive and age-related pathways. The carboxyl-terminus encodes a serine/arginine-rich (RS) region and a putative RNA recognition motif, however potential RNA-processing role(s) have remained elusive for the past 20 years. Here, we show that the RS domain of human PGC-1 directly interacts with RNA and the nuclear RNA export factor NXF1. Inducible depletion of endogenous PGC-1 and expression of RNAi-resistant RS-deleted PGC-1 further demonstrate that the RNA-binding activity is required for nuclear export of co-activated transcripts and mitochondrial homeostasis. Moreover, a quantitative proteomics approach confirmed PGC-1-dependent RNA transport and mitochondrial-related functions, identifying also novel mRNA nuclear export targets in age-related telomere maintenance. Discovering a novel function for a major cellular homeostasis regulator provides new directions to further elucidate the roles of PGC-1 in gene expression, metabolic disorders, ageing and neurodegenerative diseases.

molecular biology↗

bioRxiv2021

A cell-penetrant peptide blocking C9ORF72-repeat RNA nuclear export suppresses neurodegeneration

Hexanucleotide repeat expansions in C9ORF72 are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), a spectrum of incurable debilitating neurodegenerative diseases. Here, we report a novel ALS/FTD drug concept with in vivo and in vitro therapeutic activity in preclinical models of C9ORF72-ALS/FTD. Our data demonstrate that supplementation or oral administration of a cell-penetrant peptide, which competes with the SRSF1:NXF1 interaction, confers neuroprotection by inhibiting the nuclear export of pathological C9ORF72-repeat transcripts in various models of disease including primary neurons, patient-derived motor neurons and Drosophila. Our drug-like rationale for disrupting the nuclear export of microsatellite repeat transcripts in neurological disorders provides a promising alternative to conventional small molecule inhibitors often limited by poor blood-brain barrier penetrance.

molecular biology↗

bioRxiv2021

Safety and efficacy of C9ORF72-repeat RNA nuclear export inhibition in amyotrophic lateral sclerosis

BackgroundLoss of motor neurons in amyotrophic lateral sclerosis (ALS) leads to progressive paralysis and death. Dysregulation of thousands of RNA molecules with roles in multiple cellular pathways hinders the identification of ALS-causing alterations over downstream changes secondary to the neurodegenerative process. How many and which of these pathological gene expression changes require therapeutic normalisation remains a fundamental question. MethodsHere, we investigated genome-wide RNA changes in C9ORF72-ALS patient-derived neurons and Drosophila, as well as upon neuroprotection taking advantage of our gene therapy approach which specifically inhibits the SRSF1-dependent nuclear export of pathological C9ORF72-repeat transcripts. This is a critical study to evaluate (i) the overall safety and efficacy of the partial depletion of SRSF1, a member of a protein family involved itself in gene expression, and (ii) a unique opportunity to identify neuroprotective RNA changes. ResultsOur study demonstrates that manipulation of 362 transcripts out of 2,257 pathological changes in C9ORF72-ALS patient-derived neurons is sufficient to confer neuroprotection upon partial depletion of SRSF1. In particular, expression of 90 disease-altered transcripts is fully reverted upon neuroprotection leading to the characterisation of a human C9ORF72-ALS disease-modifying gene expression signature. These findings were further investigated in vivo in diseased and neuroprotected Drosophila transcriptomes, highlighting a list of 21 neuroprotective changes conserved with 16 human orthologues in patient-derived neurons. We also functionally validated the high therapeutic potential of one of these disease-modifying transcripts, demonstrating that inhibition of ALS-upregulated human KCNN1-3 (Drosophila SK) voltage-gated potassium channel orthologs mitigates degeneration of human motor neurons as well as Drosophila motor deficits. ConclusionsStrikingly, manipulating the expression levels of a small proportion of RNAs is sufficient to induce a therapeutic effect, further indicating that the SRSF1-targeted gene therapy approach is safe in the above preclinical models as it does not disrupt globally gene expression. The efficacy of this intervention is also validated at genome-wide level with therapeutically-induced RNA changes involved in the vast majority of biological processes affected in C9ORF72-ALS. Finally, the identification of a characteristic signature with key RNA changes modified in both the disease state and upon neuroprotection also provides potential new therapeutic targets and biomarkers.

systems biology↗

bioRxiv2020

Ankhd1 enhances polycystic kidney disease development via promoting proliferation and fibrosis.

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most common genetic kidney disorder resulting in 10% of patients with renal failure. The molecular events responsible for the relentless growth of cysts are not defined. Thus, identification of novel drivers of ADPKD may lead to new therapies. Ankyrin Repeat and Single KH domain-1 (ANKHD1) controls cancer cell proliferation, yet its role in ADPKD is unexplored. Here, we present the first data that identify ANKHD1 as a driver of proliferative growth in cellular and mouse models of ADPKD. Using the first Ankhd1-deficient mice, we demonstrate that Ankhd1 heterozygosity potently reduces cystic growth and fibrosis, in a genetically orthologous mouse model of ADPKD. We performed transcriptome-wide profiling of patient-derived ADPKD cells with and without ANKHD1 siRNA silencing, revealing a major role for ANKHD1 in the control of cell proliferation and matrix remodelling. We validated the role of ANKHD1 in enhancing proliferation in patient-derived cells. Mechanistically ANKHD1 promotes STAT5 signalling in ADPKD mice. Hence, ANKHD1 is a novel driver of ADPKD, and its inhibition may be of therapeutic benefit.

molecular biology↗