Phenotypes of myopathy-related beta-tropomyosin mutants in human and mouse tissue cultures

PLoS One. 2013 Sep 10;8(9):e72396. doi: 10.1371/journal.pone.0072396. eCollection 2013.

Abstract

Mutations in TPM2 result in a variety of myopathies characterised by variable clinical and morphological features. We used human and mouse cultured cells to study the effects of β-TM mutants. The mutants induced a range of phenotypes in human myoblasts, which generally changed upon differentiation to myotubes. Human myotubes transfected with the E41K-β-TM(EGFP) mutant showed perinuclear aggregates. The G53ins-β-TM(EGFP) mutant tended to accumulate in myoblasts but was incorporated into filamentous structures of myotubes. The K49del-β-TM(EGFP) and E122K-β-TM(EGFP) mutants induced the formation of rod-like structures in human cells. The N202K-β-TM(EGFP) mutant failed to integrate into thin filaments and formed accumulations in myotubes. The accumulation of mutant β-TM(EGFP) in the perinuclear and peripheral areas of the cells was the striking feature in C2C12. We demonstrated that human tissue culture is a suitable system for studying the early stages of altered myofibrilogenesis and morphological changes linked to myopathy-related β-TM mutants. In addition, the histopathological phenotype associated with expression of the various mutant proteins depends on the cell type and varies with the maturation of the muscle cell. Further, the phenotype is a combinatorial effect of the specific amino acid change and the temporal expression of the mutant protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism
  • Animals
  • Cells, Cultured
  • Cytoskeleton / metabolism
  • Gene Expression
  • Genetic Association Studies
  • Green Fluorescent Proteins / biosynthesis
  • Humans
  • Mice
  • Muscle Fibers, Skeletal / metabolism*
  • Muscle Fibers, Skeletal / pathology
  • Muscular Diseases / genetics*
  • Muscular Diseases / pathology
  • Myoblasts / metabolism
  • Myoblasts / pathology
  • Phenotype
  • Sarcomeres / metabolism
  • Sequestosome-1 Protein
  • Tissue Culture Techniques
  • Tropomyosin / genetics*
  • Tropomyosin / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • SQSTM1 protein, human
  • Sequestosome-1 Protein
  • Tropomyosin
  • enhanced green fluorescent protein
  • Green Fluorescent Proteins

Grants and funding

The study was supported by a grant from the Swedish Research Council (Project No. 073018 to HT) and Åke Wiberg's Foundation to HT. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.