Biology subjects

Waddington, S.

Publications and source records attributed to Waddington, S..

5 recordsLinked to original sources

bioRxiv2026

Neuronal targeted AAV Micro-Dystrophin restores neurobehavioural co-morbidities, grip strength and motor coordination in mdx52 mouse model of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a X-linked disorder caused by mutations in the DMD gene, which disrupts production of multiple isoforms of dystrophin in multiple organs namely muscle, heart and brain. While progressive muscle disease and cardiomyopathy are the hallmarks of DMD, over 40% of individuals also experience significant neurobehavioral comorbidities, including autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), obsessive compulsive disorder (OCD) and intellectual disability. These deficits are linked to the loss of brain isoforms and approximately 90% of DMD individuals have loss of either Dp427 or both Dp427 and Dp140 in the brain. We studied the mdx52 mouse model, which lacks these isoforms and exhibits severe fear and anxiety-like behaviours, suitable to evaluate the therapeutic efficacy on neuro-comorbidities after delivering a neuronal-targeted adeno-associated virus (AAV) micro-dystrophin ({micro}Dys) therapy. We compared two delivery routes intravenous (IV) and intracerebroventricular (ICV) in neonatal mdx52 male mice to assess impact on an extensive range of neurobehavioural aspects including emotional reactivity, neurocognitive, OCD and motor coordination deficits. While both routes successfully reduced emotional reactivity and anxiety-related behaviours, IV delivery emerged as the superior therapeutic strategy addressing a more comprehensive spectrum of DMD related brain co-morbidities. Critically, significant improvements in cognitive deficits and OCD-like behaviours were achieved only through IV delivery. This was associated with a widespread lower transduction pattern across the brain, including hindbrain and cerebellum, which were less effectively targeted by ICV injection, although forebrain transduction with ICV delivery was higher. Brain {micro}Dys expression successfully restored dystrophin interactors dystroglycan, syntrophin and pre- and post-synaptic functional interactors VGLUT1, gephyrin, GABAAR with both delivery methods. These results demonstrate that while ICV gene therapy results in improved emotional reactivity and anxiety-related behaviour in the mdx52, only the systemic, neuronal-targeted gene therapy efficiently transduced the central nervous system restoring neuronal synaptic functional complexes of both Dp427 and 140 isoforms and simultaneously restored peripheral NMJ dystrophin deficiency. Beyond cognitive restoration, while both routes improved aspects of gait on CatWalk XT, only IV delivery significantly enhanced motor coordination on the Beam walk and, unexpectedly, normalised grip strength. This was specifically linked to the selective expression of {micro}Dys at neuromuscular junctions (NMJs), which corrected post-synaptic electrophysiological dysfunction of mdx52 mice. Our findings establish a significant foundation for incorporating brain-directed strategies into the future therapeutic approaches for DMD, offering a holistic approach to treating DMD as a multisystemic disease.

neuroscience↗

bioRxiv2024

GENE THERAPY PREVENTS HEPATIC MITOCHONDRIAL DYSFUNCTION IN MURINE DEOXYGUANOSINE KINASE DEFICIENCY

Primary mitochondrial disorders are an uncommon cause of neonatal hepatic failure. Biallelic pathogenic variants of the gene encoding the mitochondrial localising enzyme deoxyguanosine kinase (DGUOK) cause hepatocerebral mitochondrial DNA depletion syndrome leading to acute neonatal liver failure and early mortality. There are currently no effective disease-modifying therapies. In this study, we developed an adeno-associated virus 9 (AAV9) gene therapy approach to treat a mouse model of DGUOK deficiency that recapitulates human disease. We delivered AAV9-hDGUOK gene therapy intravenously to newborn Dguok knock-out mice and showed that liver dysfunction was prevented in a dose dependent manner. Unexpectedly for neonatal delivery, durable and long-lasting liver transduction and RNA expression were demonstrated. Liver mitochondrial DNA depletion, deficiencies of oxidative phosphorylation complexes I, III and IV and liver transaminitis and survival were ameliorated in a dose-dependent manner.

genetics↗

bioRxiv2023

AAV-mediated gene therapy in a GLDC-deficient mouse model of Non-Ketotic Hyperglycinemia

Non-Ketotic Hyperglycinemia (NKH) is a rare inborn error of metabolism caused by impaired function of the glycine cleavage system (GCS) and characterised by accumulation of glycine in body fluids and tissues. NKH is an autosomal recessive condition and the majority of affected individuals carry mutations in GLDC (glycine decarboxylase). Current treatments for NKH are not effective or curative. As a monogenic condition with known genetic causation, NKH is potentially amenable to gene therapy. An AAV9-based expression vector was designed to target sites of GCS activity. Using an ubiquitous promoter to drive expression of a GFP reporter, transduction of liver and brain was confirmed following intra-venous and/or intra-cerebroventricular administration to neonatal mice. Using the same capsid and promoter with transgenes to express mouse or human GLDC, vectors were then tested in a GLDC-deficient mice that provide a model of NKH. GLDC-deficient mice exhibited elevated plasma glycine concentration and accumulation of glycine in liver and brain tissues as previously observed. Moreover, the folate profile indicated suppression of folate one carbon metabolism (FOCM) in brain tissue, as found at embryonic stages, and reduced abundance of FOCM metabolites including betaine and choline. Neonatal administration of vector achieved reinstatement of GLDC mRNA and protein expression in GLDC-deficient mice. Treated GLDC-deficient mice showed significant lowering of plasma glycine, confirming functionality of vector expressed protein. AAV9-GLDC treatment also led to lowering of brain tissue glycine, and normalisation of the folate profile indicating restoration of glycine-derived one-carbon supply. These findings support the hypothesis that AAV-mediated gene therapy may offer potential in treatment of NKH.

molecular biology↗

bioRxiv2020

Beclin-1-mediated activation of autophagy improves proximal and distal urea cycle disorders.

Urea cycle disorders (UCD) are inherited defects in clearance of waste nitrogen with high morbidity and mortality. Novel and more effective therapies for UCD are needed. Studies in mice with constitutive activation of autophagy unraveled Beclin-1 as druggable candidate for therapy of hyperammonemia. Next, we investigated efficacy of cell penetrating autophagy inducing Tat-Beclin-1 (TB-1) peptide for therapy of the two most common UCD, namely ornithine transcarbamylase (OTC) and argininosuccinate lyase (ASL) deficiencies. TB-1 reduced urinary orotic acid and hyperammonemia, and improved survival under protein-rich diet in spf-ash mice, a model of OTC deficiency (proximal UCD). In AslNeo/Neo mice, a model of ASL deficiency (distal UCD), TB-1 increased ureagenesis, reduced argininosuccinate, and improved survival. Moreover, it alleviated hepatocellular injury and decreased both cytoplasmic and nuclear glycogen accumulation in AslNeo/Neo mice. In conclusion, Beclin-1-dependent activation of autophagy improved biochemical and clinical phenotypes of proximal and distal defects of the urea cycle.

genetics↗

bioRxiv2018

Gene therapy in argininosuccinic aciduria

Argininosuccinate lyase (ASL) belongs to the liver-based urea cycle detoxifying ammonia, and the citrulline-nitric oxide cycle synthesising nitric oxide (NO). ASL-deficient patients present argininosuccinic aciduria characterised by hyperammonaemia and a multi-organ disease with neurocognitive impairment. Current therapeutic guidelines aim to control ammonaemia without considering the systemic NO imbalance. Here, we observed a neuronal disease with oxidative/nitrosative stress in ASL-deficient mouse brains. A single systemic injection of gene therapy mediated by an adeno-associated viral vector serotype 8 (AAV8) in adult or neonatal mice demonstrated the long-term correction of the urea cycle and the citrulline-NO cycle in the brain, respectively. The neuronal disease persisted if ammonaemia only was normalised but was dramatically reduced after correction of both ammonaemia and neuronal ASL activity. This was correlated with behavioural improvement and a decrease of the cortical cell death rate. Thus, the cerebral disease in argininosuccinic aciduria involves neuronal oxidative/nitrosative stress not mediated by hyperammonaemia, which is reversed by AAV gene transfer targeting the brain and the liver, acting on two different metabolic pathways via a single vector delivered systemically. This approach provides new hope for hepatocerebral metabolic diseases.

genetics↗