Rhabdomyolysis is a clinical emergency characterized by severe muscle damage, resulting in the release of intracellular muscle components, which leads to myoglobinuria and, in severe cases, acute kidney failure. Rhabdomyolysis is caused by genetic factors linked to increased disease susceptibility in response to extrinsic triggers. Recessive mutations in TANGO2 result in episodic rhabdomyolysis, metabolic crises, encephalopathy, and cardiac arrhythmia. The underlying mechanism contributing to disease onset in response to specific triggers remains unclear. To address these challenges, we created a zebrafish model of Tango2 deficiency. Here we demonstrate that the loss of Tango2 in zebrafish results in growth defects, early lethality, and increased susceptibility of skeletal muscle defects in response to extrinsic triggers similar to TANGO2 patients. Using lipidomics, we identified alterations in the glycerolipid pathway in tango2 mutants which is critical for membrane stability and energy balance. Therefore, these studies provide insight into key disease processes in Tango2 deficiency and have increased our understanding of the impacts of specific defects on predisposition to environmental triggers in TANGO2-related disorders.

Rhabdomyolysis is a clinical emergency characterized by severe muscle damage resulting in the release of intracellular muscle components leading to myoglobinuria and in severe cases, acute kidney failure. Rhabdomyolysis is caused by genetic factors that are linked to increased disease susceptibility in response to extrinsic triggers. Recessive mutations inTANGO2result in episodic rhabdomyolysis, metabolic crises, encephalopathy and cardiac arrhythmia, the underlying mechanism contributing to disease onset in response to specific triggers remains unclear. To address these challenges, we created a zebrafish model of Tango2 deficiency. Here we show that loss of Tango2 in zebrafish results in growth defects, early lethality and increased susceptibility of muscle defects similar toTANGO2patients. Detailed analyses of skeletal muscle revealed defects in the sarcoplasmic reticulum and mitochondria at the onset of disease development. The sarcoplasmic reticulum (SR) constitutes the primary lipid biosynthesis site and regulates calcium handling in skeletal muscle to control excitation-contraction coupling. Tango2 deficient SR exhibits increased sensitivity to calcium release that was partly restored by inhibition of Ryr1-mediated Ca2+release in skeletal muscle. Using lipidomics, we identified alterations in the glycerolipid state oftango2mutants which is critical for membrane stability and energy balance. Therefore, these studies provide insight into key disease processes in Tango2 deficiency and increased our understanding of how specific defects can predispose to environmental triggers in TANGO2-related disorders.

Nemaline myopathy is a rare neuromuscular disorder associated with congenital or childhood-onset of skeletal muscle weakness and hypotonia that results in limited motor function. Nemaline myopathy is a genetic disorder and mutations in 12 genes are known to contribute to autosomal dominant or recessive forms of the disease. Recessive mutations in nebulin (NEB) are the most common cause of nemaline myopathy affecting about 50% of patients. Due to the large size of the NEB gene and lack of mutational hot spots, developing therapies that can benefit a wide group of patients is challenging. Although there are several promising therapies under investigation, there is no cure for nemaline myopathy. Therefore, targeting disease modifiers that can stabilize or improve skeletal muscle function may represent alternative therapeutic strategies. Our studies have identified Nrap upregulation in nebulin deficiency that contributes to structural and functional deficits in nemaline myopathy. We show that genetic ablation of nrap in nebulin deficiency restored sarcomeric disorganization, reduced protein aggregates and improved skeletal muscle function in zebrafish. Our findings suggest that Nrap is a disease modifier that affects skeletal muscle structure and function in nemaline myopathy, thus therapeutic targeting of Nrap in nebulin related nemaline myopathy and related diseases may be beneficial for patients.