Ectopic PLAG1 induces muscular dystrophy in the mouse

Area of Science:

• Genetics and Molecular Biology
• Cardiovascular and Muscle Diseases

Background:

• Genetic mutations are known causes of muscular dystrophies (MD), but the biology of MD without identified mutations requires further investigation.
• PLAG1 is a transcription factor expressed in developing skeletal muscle and is an oncogene in certain cancers like rhabdomyosarcoma (RMS).

Purpose of the Study:

• To develop and characterize a novel mouse model of MD by inducing ectopic expression of PLAG1 in skeletal and cardiac muscle.
• To investigate the role of PLAG1 in the pathogenesis of MD and its potential link to IGF2.

Main Methods:

• Generation of Cre/PLAG1 mice by breeding LSL-PLAG1 mice with the MCK-Cre line for targeted PLAG1 expression.
• Assessment of cardiac function (left ventricle fractional shortening) and skeletal muscle histology (necrosis, fibrosis, etc.).
• Analysis of Dmd mRNA and dystrophin protein levels using QRT-PCR, Western blot, and immunofluorescence; in vitro cell culture studies.

Main Results:

• Cre/PLAG1 mice exhibited a lethal phenotype before 6 weeks, characterized by severe cardiomyopathy and dystrophic features in skeletal muscle.
• Skeletal muscle displayed myofiber necrosis, central nuclei, fatty infiltration, and fibrosis, mimicking human MD pathology.
• Ectopic PLAG1 expression led to decreased Dmd mRNA and dystrophin protein, with excess IGF2 potentially mediating this effect.

Conclusions:

• A new mouse model of lethal MD was successfully created through ectopic PLAG1 expression, impacting both cardiac and skeletal muscle.
• The findings suggest a role for PLAG1 and potentially excess IGF2 in MD pathogenesis.
• This mouse model offers a valuable tool for further research into MD mechanisms and the development of new therapeutic strategies.