Brody Disease: Utilizing a Novel Zebrafish Animal Model for Exploring Potential Therapeutic Strategies for this Rare Human Condition

Brody disease is a “rare” genetic disorder characterised by exercise-induced muscle stiffness and impairment of relaxation (Brody 1996). Bovine “congenital pseudomyotonia” (PMT) is a genetic muscular disorder similar to human Brody myopathy. Missense mutations in the ATP2A1 gene (Drögemüller et al 2008), encoding sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA1), cause congenital PMT in cattle and Brody myopathy in humans. The mouse is commonly used as an animal model for preclinical testing of novel therapeutic compounds. However, it is not suitable for studying Brody myopathy due to the high presence of type II muscle fibers in the diaphragm. Clinical symptoms, genetic information, and biochemical evidence have shown that congenital PMT in Chianina cattle serves as a genuine equivalent mammal to Brody disease (Sacchetto et al. in 2009). We have recently introduced a novel pharmacological strategy that revolves around the utilization of protein folding correctors, specifically CFTR (Cystic Fibrosis Transmembrane Regulator) (European Patent EU 2925317), which have been extensively studied in the context of Cystic Fibrosis. We've successfully demonstrated the effectiveness of the C17 corrector in restoring the expression of mutated SERCA1 in both in-vitro and in-vivo settings, where local muscle treatment was administered to cattle affected with PMT (manuscript in preparation). However, it's worth noting that large animals are not suitable for systemic drug administration. Due to the unavailability of an ideal mouse model, we decided to employ the commercially available natural mutant Zebrafish Accordion, which carries the S766F SERCA1 mutation, as an essential tool to validate the effectiveness and safety of our innovative therapeutic approach. Simultaneously, we utilised CRISPR/Cas9 technology to manipulate the zebrafish genome, creating a mutant line that carries the SERCA1 mutation observed in bovine PMT. This allowed us to establish the suitability of this mutated zebrafish line as a novel animal model for studying human Brody disease. Our objective is to translate the use of the CFTR C17 small molecule into a therapeutic solution for people who have Brody myopathy.