Expression of Myomaker and Myomerger in myofibers causes muscle pathology

Skeletal Muscle

Research

Chengyi Sun¹  Phillip C. Witcher¹  Douglas P. Millay² 

[1] Division of Molecular Cardiovascular Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA;Division of Molecular Cardiovascular Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA;Department of Pediatrics, University of Cincinnati College of Medicine, 45229, Cincinnati, OH, USA;

关键词: Myomaker;    Myomerger/Myomixer;    Muscle pathology;    Myocyte fusion;   

DOI  :  10.1186/s13395-023-00317-z

 received in 2022-12-16, accepted in 2023-04-17,  发布年份 2023

来源: Springer

【 摘 要 】

BackgroundSkeletal muscle development and regeneration depend on cellular fusion of myogenic progenitors to generate multinucleated myofibers. These progenitors utilize two muscle-specific fusogens, Myomaker and Myomerger, which function by remodeling cell membranes to fuse to each other or to existing myofibers. Myomaker and Myomerger expression is restricted to differentiating progenitor cells as they are not detected in adult myofibers. However, Myomaker remains expressed in myofibers from mice with muscular dystrophy. Ablation of Myomaker from dystrophic myofibers results in reduced membrane damage, leading to a model where persistent fusogen expression in myofibers, in contrast to myoblasts, is harmful.MethodsDox-inducible transgenic mice were developed to ectopically express Myomaker or Myomerger in the myofiber compartment of skeletal muscle. We quantified indices of myofiber membrane damage, such as serum creatine kinase and IgM+ myofibers, and assessed general muscle histology, including central nucleation, myofiber size, and fibrosis.ResultsMyomaker or Myomerger expression in myofibers independently caused membrane damage at acute time points. This damage led to muscle pathology, manifesting with centrally nucleated myofibers and muscle atrophy. Dual expression of both Myomaker and Myomerger in myofibers exacerbated several aspects of muscle pathology compared to expression of either fusogen by itself.ConclusionsThese data reveal that while myofibers can tolerate some level of Myomaker and Myomerger, expression of a single fusogen above a threshold or co-expression of both fusogens is damaging to myofibers. These results explain the paradigm that their expression in myofibers can have deleterious consequences in muscle pathologies and highlight the need for their highly restricted expression during myogenesis and fusion.

【 授权许可】

CC BY   
© The Author(s) 2023

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