Biology subjects

Kourakis, S.

Publications and source records attributed to Kourakis, S..

5 recordsLinked to original sources

bioRxiv2026

ADSS1 is a suppressed metabolic control node in dystrophic skeletal muscle

Duchenne muscular dystrophy is initiated by dystrophin loss but is accompanied by profound metabolic remodelling. Here, we identify suppression of the muscle-enriched adenylosuccinate synthase, ADSS1, and the purine nucleotide cycle in mdx muscle. Integrated multi-omic profiling revealed a compensated purine-stress state in which nucleotide salvage and quality control were increased to preserve adenine nucleotide abundance and buffer consequential toxic/disruptive deoxy-/nucleotide production. Purine metabolism was the highest-impact joint pathway with metabolite and transcript hits in mdx muscle, and its maintenance program was directionally conserved in human ADSS1 myopathy. Interventions positioned around ADSS1 separated the outputs of this node. Ribose and dimethyl fumarate remodelled upstream or downstream stress programs, whereas only adenylosuccinic acid bypassed ADSS1 to expand the adenine nucleotide pool and remodel CoA/acetyl-CoA metabolism. All three interventions suppressed pro-adipogenic transcription without broadly correcting the lipidome. These findings identify ADSS1 as a regulated metabolic control node that couples purine retention to inflammatory and adipogenic remodelling in dystrophic muscle.

molecular biology↗

bioRxiv2026

Endocrine-metabolic decoupling drives stress vulnerability in dystrophin deficiency

Skeletal muscle orchestrates systemic metabolism, dynamically coordinating glucose uptake and fuel use to match energy demand. In Duchenne muscular dystrophy, loss of dystrophin is associated with altered metabolic regulation. In the mdx mouse, we show that physiological stress reveals impaired coordination between insulin and stress responses: glucocorticoid signalling increases without a proportional rise in insulin secretion, resulting in systemic hyperglycaemia despite preserved capacity for muscle glucose uptake. These data support a multi-tissue dystrophinopathy associated with altered endocrine-metabolic coordination. Skeletal muscle glycogen is elevated and incompletely mobilised under stress. The heart maintains high glucose uptake, whereas the brain exhibits reduced uptake, highlighting tissue specific differences in metabolic response. Acute insulin supplementation improves systemic glucose control and restores stress-induced behavioural deficits. Likewise, empagliflozin-mediated glucose offloading reduces stress-associated blood glucose spikes and is associated with improved muscle function to levels comparable with standard care prednisolone. These findings identify impaired coordination of endocrine and metabolic responses during stress as a contributor to metabolic vulnerability in DMD and suggest that modulating insulin availability or glucose flux can improve systemic metabolic control.

systems biology↗

bioRxiv2024

Moderate-term dimethyl fumarate treatment reduces pathology of dystrophic skeletal and cardiac muscle in a mouse model

In Duchenne muscular dystrophy (DMD), corticosteroids significantly slow disease progression and have been used as a standard of care tool for more than 30 years. However, corticosteroids also impart side effects severe enough to preclude use in some patients. There remains an unmet need for new therapeutics that target the flow-on pathogenic mechanisms of DMD with a more favourable side-effect profile. We have previously demonstrated that short-term treatment with dual-purpose anti-inflammatory, anti-oxidative dimethyl fumarate (DMF), a drug with indication and established safety data in Multiple Sclerosis, more selectively modulates Duchenne (mdx) immunology than the frequently used corticosteroid, prednisone (PRED). Here, we assess the effect of moderate-term DMF treatment over 5 weeks in the typically mild mdx mouse model that we aggravated using exercise. We show that like PRED, DMF maintains anti-inflammatory action but with additional anti-fibrotic and anti-lipogenic effects on muscle with moderate-term use. This study supports our previous work highlighting DMF as a possible repurposing candidate for DMD, especially for patients who cannot tolerate chronic corticosteroid treatment.

pathology↗

bioRxiv2024

Loss of endogenous estrogen alters mitochondrial metabolism and muscle clock-related protein Rbm20 in female mdx mice

Female carriers of a Duchenne muscular dystrophy (DMD) gene mutation manifest exercise intolerance and metabolic anomalies that may be exacerbated following menopause due to the loss of estrogen, a known regulator of skeletal muscle function and metabolism. Here, we studied the impact of estrogen depletion (via ovariectomy) on exercise tolerance and muscle mitochondrial metabolism in female mdx mice and the potential of estrogen replacement therapy (using estradiol) to protect against functional and metabolic perturbations. We also investigated the effect of estrogen depletion, and replacement, on the skeletal muscle proteome through an untargeted proteomic approach with TMT-labelling. Our study confirms that loss of estrogen in female mdx mice reduces exercise capacity, tricarboxylic acid cycle intermediates and citrate synthase activity but that these deficits can be offset through estrogen replacement therapy. Furthermore, ovariectomy downregulated protein expression of RNA binding motif factor 20 (Rbm20), a critical regulator of sarcomeric and muscle homeostasis gene splicing, which impacted pathways involving ribosomal and mitochondrial translation. Estrogen replacement modulated Rbm20 protein expression and promoted metabolic processes and the upregulation of proteins involved in mitochondrial dynamics and metabolism. Our data suggests that estrogen mitigates dystrophinopathic features in female mdx mice and that estrogen replacement may be a potential therapy for post-menopausal DMD carriers.

pathology↗

bioRxiv2022

Dimethyl fumarate modulates the Duchenne muscular dystrophy disease program following short-term treatment in mdx mice

New medicines are urgently required to treat the fatal neuromuscular disease, Duchenne muscular dystrophy (DMD). DMD involves progressive muscle damage and weakness, which are preceded by oxidative stress, inflammation, and mitochondrial dysfunction. Dimethyl fumarate (DMF) is a potent small molecule nuclear erythroid 2-related factor 2 (Nrf2) activator with current clinical utility in the treatment of multiple sclerosis and psoriasis. Pharmaceutical targeting of Nrf2 by DMF has strong translational potential for DMD, given it: (1) promotes antioxidant defence systems; (2) has a potent immuno-modulatory profile; and (3) can be rapidly re-purposed into clinical care strategies for DMD patients. Here, we tested two weeks of daily 100mg/kg DMF versus 5mg/kg standard care prednisone (PRED) treatment during the peak muscle degeneration period in juvenile mdx mice, the gold standard murine DMD model. Both drugs modulated seed genes driving the DMD disease program and improved muscle force production in fast-twitch muscle. However, only DMF showed pro-mitochondrial effects that protected contracting muscles from fatigue, improved histopathology and augmented clinically compatible muscle function tests. In contrast, PRED treatment stunted mouse growth, worsened histopathology and modulated many normally expressed inflammatory and extracellular matrix (ECM) genes consistent with pan immunosuppression. These findings suggest DMF could be a more selective modulator of the DMD disease program with better efficacy and fewer side effects than standard care PRED therapy warranting follow-up studies to progress clinical translation.

pathology↗