Generation of zebrafish model for limb-girdle muscular dystrophy 2A


Muscle Regeneration in Disease (includes satellite cells)

Poster Number: 110


Lucia Caceres, PhD, Sergey V. Prykhozhij, Jason Berman, Eric Hoffman, PhD, Kanneboyina Nagaraju, DVM, PhD


1. AGADA BioSciences, 2. Children’s Hospital of Eastern Ontario (CHEO) Research Institute, University of Ottawa, Ontario, Can, 3. Children’s Hospital of Eastern Ontario (CHEO) Research Institute, University of Ottawa, Ontario, Can, 4. Binghamton University, 5. Binghamton University

Background: Limb-Girdle Muscular Dystrophy Type 2A (LGMD2A) is characterized by progressive muscle weakness in the limb and girdle muscles. Mutations in the Calpain 3 gene represent one of the most common causes of LGMD 2A. We have taken advantage of the genetically amenable zebrafish to generate a vertebrate model for LGDM 2A. The rapid, ex-utero development and translucent embryos allow for rapid visualization of muscles in vivo, coupled with their small size and the large numbers makes zebrafish an ideal animal model for high-throughput chemical and behavioral screening. Methods: Calpain 3B (capn3b) encodes the human homologue of Calpain 3. A loss of function mutation (mut1) in the zebrafish capn3b gene was generated using CRISPR/Cas9 mutagenesis. We place fish in fish water containing 0.5% methylcellulose to stress the fish and visualized the muscle phenotype in live animals with polarized light (birefringence) under a stereomicroscope. Results: Consistent with our bioinformatic analysis, which predicts no protein products being generated from the mut1 mRNA, in-situ hybridization assay reveals the presence of Capn3b mRNA in skeletal muscles of wildtype fish but not in its mutant counterpart. Interestingly, the skeletal muscle phenotype of capn3b was indistinguishable from that of its wild-type counterpart. However, upon exposure to viscous medium containing 0.5% methylcellulose, a significant number of capn3b homozygote mutant fish exhibited impaired muscle phenotype resulting in early death. Conclusion: We have developed, and are in the process of characterizing, a novel zebrafish model for LGMD 2A. These capn3b mutant fish provide a tractable model for not only studying the mechanism of muscle repair and remodeling but for whole animal therapeutics and behavioral screenings. This is of importance when an assessing the specificity, efficacy and toxicity of small molecules in the context of whole animal development.