Calcium homeostasis in myogenic differentiation factor 1 (MyoD)-transformed, virally-transduced, skin-derived equine myotubes.
Authors: Fernandez-Fuente Marta, Terracciano Cesare M, Martin-Duque Pilar, Brown Susan C, Vassaux Georges, Piercy Richard J
Journal: PloS one
Summary
# Editorial Summary: Calcium Homeostasis in Equine Myotubes Calcium dysregulation within skeletal muscle underpins several significant equine and human myopathies, most notably recurrent exertional rhabdomyolysis (RER) in Thoroughbreds and genetic disorders linked to ryanodine receptor 1 (RYR1) mutations. Traditionally, investigating these calcium handling defects required invasive muscle biopsies subjected to caffeine challenge—a test of limited availability and impractical for valuable athletic animals. Fernandez-Fuente and colleagues developed and validated a non-invasive cellular model using equine skin fibroblasts genetically reprogrammed to skeletal muscle cells via MyoD transduction, then characterised their calcium homeostasis and responses to dantrolene (the prophylactic agent used for RER management). This in vitro approach proved capable of detecting meaningful calcium dynamics and pharmacological responses, offering a less invasive avenue for screening RYR1 polymorphisms of uncertain significance identified through genetic sequencing and potentially for pre-emptive identification of RER-susceptible individuals. The practical value lies in enabling targeted investigation of candidate gene variants without repeated biopsy, supporting more informed breeding and training decisions whilst reducing welfare concerns associated with invasive testing protocols.
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Practical Takeaways
- •This in vitro model could enable non-invasive screening of horses for RYR1-associated calcium handling defects without requiring muscle biopsy, particularly useful for identifying RER-susceptible animals in training
- •The technique allows testing of novel RYR1 gene variants identified through genetic sequencing to determine their pathological significance before clinical use of the findings
- •Dantrolene responsiveness can be assessed in cultured cells from individual horses, potentially guiding prophylactic treatment decisions for RER-affected animals
Key Findings
- •MyoD-transduced equine skin fibroblasts can be successfully converted to muscle lineage cells for studying calcium homeostasis in vitro
- •The cultured myotubes demonstrate calcium handling responses to RYR1 agonists and antagonists, including dantrolene
- •This model provides a less invasive alternative to traditional muscle biopsy and caffeine contracture testing for assessing calcium dyshomeostasis