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

• Published in: PloS one 2013-09, Vol.8 (9), p.e72396
• Main Authors: Abdul-Hussein, Saba, Rahl, Karin, Moslemi, Ali-Reza, Tajsharghi, Homa
• Format: Article
• Language: English
• Subjects: ACTIN CYTOSKELETON; Adaptor Proteins, Signal Transducing - metabolism; Amino acids; Animals; CAP DISEASE; Cell culture; Cells (Biology); Cells, Cultured; Clinical Medicine; Cloning; Combinatorial analysis; COMPOSITION; Congenital diseases; CONGENITAL MYOPATHY; Cytomegalovirus; Cytoskeleton - metabolism; DISTAL ARTHROGRYPOSIS; Filaments; Gene Expression; GENE TPM2; Genes; Genetic aspects; Genetic Association Studies; Green Fluorescent Proteins - biosynthesis; Humans; IMMUNOELECTRON; ISOFORM; Klinisk medicin; Medical sciences; Medicin; Mice; MICROSCOPY; Morphology; Muscle contraction; Muscle Fibers, Skeletal - metabolism; Muscle Fibers, Skeletal - pathology; Muscle proteins; Muscles; Muscular Diseases - genetics; Muscular Diseases - pathology; Musculoskeletal system; Mutagenesis; Mutants; Mutation; Myoblasts; Myoblasts - metabolism; Myoblasts - pathology; Myopathy; Myotubes; NEMALINE MYOPATHY; Pathology; Phenotype; Phenotypes; Proteins; RARE CAUSE; Sarcomeres - metabolism; Sequestosome-1 Protein; SKELETAL-MUSCLE; Studies; Tissue culture; Tissue Culture Techniques; Tropomyosin; Tropomyosin - genetics; Tropomyosin - metabolism
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0072396

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.