Phenotypes of Myopathy-Related Beta-Tropomyosin Mutants in Human and Mouse Tissue Cultures

• 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 beta-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-beta-TMEGFP mutant showed perinuclear aggregates. The G53ins-beta-TMEGFP mutant tended to accumulate in myoblasts but was incorporated into filamentous structures of myotubes. The K49del-beta-TMEGFP and E122K-beta-TMEGFP mutants induced the formation of rod-like structures in human cells. The N202K-beta-TMEGFP mutant failed to integrate into thin filaments and formed accumulations in myotubes. The accumulation of mutant beta-TMEGFP 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 beta-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.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Neurologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Neurology (hsv//eng)

Nyckelord

NEMALINE MYOPATHY

SKELETAL-MUSCLE

CAP DISEASE

IMMUNOELECTRON

MICROSCOPY

DISTAL ARTHROGRYPOSIS

CONGENITAL MYOPATHY

ISOFORM

COMPOSITION

ACTIN CYTOSKELETON

RARE CAUSE

GENE TPM2

Medical sciences

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