Biology subjects

Hantraye, P.

Publications and source records attributed to Hantraye, P..

5 recordsLinked to original sources

bioRxiv2025

AAV-mediated allele-specific silencing alleviates neuropathology in a novel non-human primate model of Spinocerebellar ataxia type 3

Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease (MJD), is an autosomal dominant neurodegenerative disorder caused by an abnormal expansion of the cytosine-adenine-guanine (CAG) repeats in the ATXN3 gene. This mutation results in the production of an Ataxin-3 protein with an extended polyglutamine sequence, contributing to the diseases neuropathology. Currently, no treatment is available that can slow or halt the progression of SCA3. Gene-targeted therapies have gained significant attention for their potential to address the root cause of SCA3. Preliminary studies in transgenic mice using adeno-associated viral vector serotype 9 (AAV9) encoding artificial microRNAs targeting the mutant ATXN3 allele (AAV9-miR-ATXN3) have shown promising results. However, to advance this therapeutic approach toward clinical application, further studies in an animal model that more closely resembles human biology are essential. In this exploratory study, we assessed the biodistribution and target engagement of AAV9-miR-ATXN3 delivered via intracisterna magna (ICM) injection in non-human primates (NHPs). Using a lentiviral vector (LV) to introduce a mutant Ataxin-3 cDNA with 72 glutamines (LV-mutATXN3-Q72) into the NHP cerebellum, we successfully overexpressed SCA3 in the NHP brain. SCA3 NHP exhibited Ataxin-3 aggregation in the cerebellum, recruitment of inflammatory cells and reduced cerebellar volume. ICM administration of AAV9-miR-ATXN3 effectively directed transgene expression to key brain regions impacted by SCA3 pathology and enabled specific, dose-dependent silencing of mutant Ataxin-3. Furthermore, the therapeutic dose prevented the cerebellar morphological and biochemical alterations induced by the overexpression of mutant ATXN3. These proof-of-concept experiments are crucial, not only for advancing AAV9-miR-ATXN3 toward clinical use but also for establishing a valuable platform for validating future therapeutic interventions.

molecular biology↗

bioRxiv2021

The JAK2-STAT3 pathway controls a beneficial proteostasis response of reactive astrocytes in Huntington disease

Huntingtons disease is a fatal neurodegenerative disease characterized by striatal neurodegeneration, aggregation of mutant Huntingtin and the presence of reactive astrocytes. Astrocytes are important partners for neurons and engage in a specific reactive response in Huntingtons disease that involves morphological, molecular and functional changes. How reactive astrocytes contribute to Huntingtons disease is still an open question, especially because their reactive state is poorly reproduced in experimental mouse models. Here, we show that the JAK2-STAT3 pathway, a central cascade controlling astrocyte reactive response, is activated in the putamen of Huntingtons disease patients. Selective activation of this cascade in astrocytes through viral gene transfer reduces the number and size of mutant Huntingtin aggregates in neurons and improves neuronal defects in two complementary mouse models of Huntingtons disease. It also reduces striatal atrophy and increases glutamate levels, two central clinical outcomes measured by non-invasive magnetic resonance imaging. Moreover, astrocyte-specific transcriptomic analysis shows that activation of the JAK2-STAT3 pathway in astrocytes coordinates a transcriptional program that increases their intrinsic proteolytic capacity, through the lysosomal and ubiquitin-proteasome degradation systems. This pathway also enhances their production and exosomal release of the co-chaperone DNAJB1, which contributes to mutant Huntingtin clearance in neurons. Together, our results show that the JAK2-STAT3 pathway controls a beneficial proteostasis response in reactive astrocytes in Huntingtons disease, which involves bi-directional signalling with neurons to reduce mutant Huntingtin aggregation, eventually improving disease outcomes.

neuroscience↗

bioRxiv2020

Optogenetic therapy: High spatiotemporal resolution and pattern recognition compatible with vision restoration in non-human primates

Restoring vision using optogenetics is an ideal medical application because the eye offers a direct window to access and stimulate the pathological area: the retina. Optogenetic therapy could be applied to diseases with photoreceptor degeneration such as retinitis pigmentosa. Here, we select the specific optogenetic construct that is now used in the clinical trial and assess the opsin functional efficacy on non-human primates retinal ganglion cells (RGCs). We chose the microbial opsin ChrimsonR and showed that the vector AAV2.7m8 produced greater transfection in RGCs compared to AAV2, and that ChrimsonR attached to tdTomato (ChR-tdT) is more efficiently expressed than ChrimsonR. The 600 nm light activates the RGCs transfected with the vector AAV2.7m8-ChR-tdT from an irradiance of 1015 photons.cm-2.s-1. Vector doses of 5.1010 and 5.1011 vg/eye transfect up to 7000 RGCs/mm2 in the perifovea, with no significant immune reaction. Furthermore, using a multielectrode array we recorded RGCs responses starting from 1ms stimulus duration. Using the recorded activity we were able to decode stimulus information and estimate a theoretical visual acuity of 20/249, above legal blindness. Altogether, our results pave the way for the ongoing clinical trial with the AAV2.7m8-ChrimsonR-tdT vector for vision restoration in patients affected by retinitis pigmentosa. One Sentence SummaryWe select here the vector and genetic construct best suited to provide vision restoration in patients suffering from retinopathies, we demonstrate temporal resolution compatible with high dynamic visual scenes and a visual acuity above legal blindness.

neuroscience↗

bioRxiv2019

Complex roles for reactive astrocytes in the triple transgenic mouse model of Alzheimer disease

In Alzheimer disease (AD), astrocytes undergo complex changes and become reactive. The consequences of this reaction are still unclear. To evaluate the net impact of reactive astrocytes in AD, we recently developed viral vectors targeting astrocytes that either activate or inhibit the JAK2-STAT3 pathway, a central cascade controlling astrocyte reaction.\n\nWe aimed to evaluate whether reactive astrocytes contribute to Tau as well as amyloid pathologies in the hippocampus of 3xTg-AD mice, an AD model that develops Tau hyperphosphorylation and aggregation in addition to amyloid deposition. JAK2-STAT3 pathway-mediated modulation of reactive astrocytes in the hippocampus of 3xTg-AD mice, did not significantly influence Tau phosphorylation or amyloid processing and deposition, at early, advanced and terminal stage of the disease. Interestingly, inhibition of the JAK2-STAT3 pathway in hippocampal astrocytes did not improve short-term spatial memory in the Y maze but it reduced anxiety in the elevated plus maze. Our unique approach to specifically manipulate reactive astrocytes in situ show these cells may impact behavioral outcomes without influencing Tau or amyloid pathology.

neuroscience↗

bioRxiv2018

Diffusion-weighted magnetic resonance spectroscopy enables cell-specific monitoring of astrocyte reactivity in vivo

The diffusion of brain intracellular metabolites, as measured using diffusion-weighted magnetic resonance spectroscopy in vivo, is thought to specifically depend on the cellular structure constraining them. However, it has never been established that variations of metabolite diffusion, e.g. as observed in some diseases, could indeed be linked to alterations of cellular morphology. Here we demonstrate, in a mouse model of reactive astrocytes, that advanced diffusion-weighted magnetic resonance spectroscopy acquisition and modeling techniques enable non-invasive detection of reactive astrocyte hypertrophy (increased soma radius, increased fiber radius and length), as inferred from variations of myo-inositol diffusion, and as confirmed by confocal microscopy ex vivo. This establishes that specific alterations of intracellular metabolite diffusion can be measured and related to cell-specific morphological alterations. Furthermore, as reactive astrocytes are a hallmark of many brain pathologies, this work opens exciting perspectives for neuroscience and clinical research.

bioinformatics↗