A Splice Site Mutation in Laminin-α2 Results in a Severe Muscular Dystrophy and Growth Abnormalities in Zebrafish

• DOI: 10.1371/journal.pone.0043794
• Publication Date: 2012-08-27T21:13:43Z
• Authors: Vandana A. Gupta; Genri Kawahara; Jennifer A. Myers; Aye T. Chen; Thomas E. Hall; M. Chiara Manzini; Peter D. Currie; Yi Zhou; Leonard I. Zon; Louis M. Kunkel; Alan H. Beggs
• Keywords: 0301 basic medicine; 570; Anatomy and Physiology; 1300 Biochemistry; Science; Muscle Fibers, Skeletal; 610; Genetics and Molecular Biology; Muscular Dystrophies; 1100 Agricultural and Biological Sciences; 03 medical and health sciences; Model Organisms; Genetic Mutation; Genetics; Animals; Humans; Biology; Musculoskeletal System; Musculoskeletal Anatomy; Zebrafish; Base Sequence; Q; R; Human Genetics; Muscle Biochemistry; Animal Models; Molecular Development; Zebrafish Proteins; Extracellular Matrix; Multidisciplinary Sciences; 2700 Medicine; Genetics of Disease; Mutation; Muscle; Science & Technology - Other Topics; Medicine; Laminin; RNA Splice Sites; Developmental Biology; Research Article

Congenital muscular dystrophy (CMD) is a clinically and genetically heterogeneous group of inherited muscle disorders. In patients, muscle weakness is usually present at or shortly after birth and is progressive in nature. Merosin deficient congenital muscular dystrophy (MDC1A) is a form of CMD caused by a defect in the laminin-α2 gene (LAMA2). Laminin-α2 is an extracellular matrix protein that interacts with the dystrophin-dystroglycan (DGC) complex in membranes providing stability to muscle fibers. In an N-ethyl-N-nitrosourea mutagenesis screen to develop zebrafish models of neuromuscular diseases, we identified a mutant fish that exhibits severe muscular dystrophy early in development. Genetic mapping identified a splice site mutation in the lama2 gene. This splice site is highly conserved in humans and this mutation results in mis-splicing of RNA and a loss of protein function. Homozygous lama2 mutant zebrafish, designated lama2(cl501/cl501), exhibited reduced motor function and progressive degeneration of skeletal muscles and died at 8-15 days post fertilization. The skeletal muscles exhibited damaged myosepta and detachment of myofibers in the affected fish. Laminin-α2 deficiency also resulted in growth defects in the brain and eye of the mutant fish. This laminin-α2 deficient mutant fish represents a novel disease model to develop therapies for modulating splicing defects in congenital muscular dystrophies and to restore the muscle function in human patients with CMD.