Cellular, electrophysiological and behavioral improvements in a mouse model of Rett syndrome following gene therapy combined with focused ultrasound-mediated blood-brain barrier opening.
It is demonstrated that using FUS following systemic administration of an AAV9 vector represents a significant improvement over classical gene therapy protocol for RTT, and the evaluation of the protein levels indicates a possible overdose of Mecp2 protein in the brain cells.
Abstract
Rett syndrome (RTT) is a severe X-linked neurodevelopmental disorder due to pathogenic variants in the methyl CpG binding protein 2 gene (MECP2). The discovery that deficits resulting from Mecp2 loss are reversible in mice has increased interest in gene therapy as a potential cure for RTT. We have previously evaluated the efficacy of a self-complementary AAV9 vector expressing a codon-optimized version of Mecp2 (scAAV9-MCO) delivered via a systemic approach in early symptomatic Mecp2-knock-out male (KO) mice. In the present study, focused ultrasound (FUS) was used to transiently disrupt the blood-brain barrier (BBB) in a RTT mouse model, thereby facilitating enhanced AAV delivery to the central nervous system (CNS). Our findings demonstrate that scAAV9-MCO administration, when combined with FUS, significantly improves survival, body weight, respiratory function, and locomotor activity, while restoring the excitatory-inhibitory synaptic balance in hippocampal neurons in treated KO mice relative to untreated animals. Quantification of the brain infection level revealed that 20-40% of cells are Mecp2-positive in the brain of KO mice following the treatment with scAAV9-MCO and FUS. This is a significant improvement compared to prior results without FUS. The evaluation of the protein levels indicates a possible overdose of Mecp2 protein in the brain cells. Nevertheless, these results demonstrate that using FUS following systemic administration of an AAV9 vector represents a significant improvement over classical gene therapy protocol for RTT.
The heterotrimeric G proteins are ubiquitous membrane-bound complexes specialized in the transduction of receptor-mediated extracellular signals into intracellular responses. Mutations in the G protein subunit alpha O1 (Gαo), encoded by GNAO1, have been associated with neurodevelopmental disorders characterized by prominent movement disorder with or without epilepsy. The Gnao1[C215Y]/+ mouse model recapitulates key features of the human disease, with a relatively mild phenotype, normal viability and late onset movement abnormalities, detectable in specific motor tasks. Here we report functional alterations in cortical layer V pyramidal neurons from Gnao1[C215Y]/+ mice, with reduction of the inward currents (Ih) and impairment of the GABAB-mediated outward current. We propose an adeno-associated virus (AAV)-based gene therapy aimed at overexpressing the wild-type form of Gαo by intracerebroventricular injection in newborn heterozygous Gnao1[C215Y]/ + mice. Our results demonstrate that overexpression of the wild-type protein mitigates behavioral abnormalities and restores functional neuronal deficits in young adult mice, thereby supporting the development of AAV-mediated gene augmentation strategies to counteract the effects of GNAO1 variants in patients. The potential of gene supplementation therapy is further supported by data from genetically modified C. elegans strains carrying not only the relatively mild C215Y variant but also a panel of goa-1/GNAO1 mutations associated with more severe phenotypes, suggesting a broader potential of this therapeutic strategy.
Germana Cocozza, T. D’Andrea, Martina Di Rocco et al.· Acta Neuropathologica Commun...· 0 citations
It is shown that FMR1 gene therapy using delivery routes and vehicles approved for clinical use improves core phenotypes in a mouse model for FXS, and suggests that a dual route may be needed to achieve full brain coverage.
Richard K Lacher, Kari Henson, Lindsay N Wathen et al.· Gene Therapy· 0 citations
This study evaluates the therapeutic potential of the lipid-conjugated antimiR-23b, X82108, designed to promote MBNL1/2 upregulation through inhibition of miR-23b, and highlights X82108 as a promising systemic therapy for DM1.
D. Piqueras-Losilla, Andrea García-Rey, Aline Huguet-Lachon et al.· Cell Reports Medicine· 0 citations
Cockayne Syndrome (CS) is an autosomal recessive, progressive developmental and neurodegenerative disease. Approximately 30% of cases are caused by mutations in the ERCC8/CSA gene. Patients with CS present with cutaneous photosensitivity, growth failure, shorter life span, and a progressive degeneration of the central nervous system. Loss-of-function mutations in CSA result in deficiencies in the transcription-coupled nucleotide excision repair (TC-NER). Currently, no therapies are available for these patients. Adeno-associated virus (AAV)-mediated gene therapy offers an opportunity to address this unmet need. We designed a new AAV vector encoding human CSA under a ubiquitous promoter. We tested the therapeutic efficacy of this AAV9-CSA vector by neonatal intracerebroventicular injection in the Csa-/-;Xpa-/- mouse model. Treatment with AAV9-CSA resulted in a significant increase in lifespan, and broad distribution of human CSA in the brain and heart, without evidence of vector-related toxicity. Despite clear therapeutic benefit, we also observed neuroradiological abnormalities, and neuropathologic alterations, including hypomyelination, astrocytosis, and microgliosis, as well as likely life-limiting transcriptomic alterations in liver at endpoint. Nonetheless, the success of these experiments paves the way for the first clinical translation of an AAV gene therapy for CS patients into humans.
A. R. Batista, Aine C. Scholand, William S. Callahan et al.· Journal of Clinical Investig...· 0 citations
The beta-site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1) is a promising and rational target for Alzheimer’s disease (AD), but current clinical trials have been disappointing. Consequently, utilizing the intrinsic regulatory mechanisms of BACE1 during AD pathogenesis might provide valuable insights into the treatment of this devastating disease. In this study, we proposed a combination of AAV delivery and microRNA therapeutics targeting AD at its root by sustained and spatial inhibition of BACE1 with a single therapeutic injection. We demonstrate that upregulation of BACE1 is correlated with downregulation of miR-143-3p in the hippocampus of individuals with AD, and miR-143-3p can directly target BACE1 to inhibit Aβ generation. In the brains of 5×FAD model mice, BACE1 levels are found to be elevated with age in the cornu ammonis 1 (CA1) subfield of the hippocampus. AAV-mediated miR-143-3p restoration in the hippocampal CA1 subfield of AD mice can improve cognitive performance, attenuate BACE1 expression, reduce Aβ levels, induce microglia polarization toward the anti-inflammatory phenotype, modulate neural-related genes including Gal3, and promote synaptic functions. Collectively, the AAV-mediated microRNA gene therapy approach developed for spatial suppression of BACE1 can effectively enhance cognitive performance in AD model mice, offering an attractive therapeutic option for AD treatment with long-lasting efficacy.
Ying Zhou, Yuelin Diao, Zhexiao Yan et al.· Biomolecules· 0 citations
OBJECTIVE
Repeat expansion mutations underlie diverse neurogenetic disorders, many involving the peripheral nervous system. Despite peripheral neuropathy being the most common neurological disorder worldwide, its contribution to repeat expansion diseases remains poorly defined, and robust preclinical models are limited. We established a translational framework to study peripheral neuropathy in spinocerebellar ataxia type 3 (SCA3), a fatal multisystem disorder caused by a pathogenic CAG expansion in ATXN3.
METHODS
SCA3 Knock-In Atxn3Q300/Q6 (KI) and Atxn3-/- Knock-Out (KO) mice underwent sensorimotor nerve conduction and behavioral testing. Peripheral tissues were evaluated for SCA3-related pathology, and transcriptional changes in KI dorsal root ganglia (DRG) were assessed by bulk RNA sequencing. To test therapeutic relevance, we generated a conditional "OFF" SCA3 knock-in (cKI) mouse and crossed it with Avil-Cre to selectively silence mutant ATXN3 in sensory neurons. Peripheral phenotyping was repeated in Avil-Cre; cKI mice.
RESULTS
KI mice developed progressive sensorimotor deficits, peripheral histopathology, and RNA splicing dysregulation that parallel clinical features of SCA3. In contrast, KO mice showed normal peripheral nerve function, implicating toxic gain-of-function from mutant ATXN3 as the causative driver. Sensory neuron-specific silencing of mutant ATXN3 significantly ameliorated peripheral nerve abnormalities and DRG splicing dysregulation.
INTERPRETATION
These findings define a pathogenic role for repeat expansion-driven peripheral nerve degeneration in SCA3, identify sensory neurons as key therapeutic targets, and provide a preclinical platform for developing peripheral interventions in SCA3 and related repeat expansion disorders. ANN NEUROL 2026.
Juan P Mato, John M. Hayes, Jacen Emerson et al.· Annals of Neurology· 0 citations
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