Figure 7. The expression of WT and mutant β-TMs-_EGFP in human myotubes.

WT and mutant β-TMs were transfected in human myotubes differentiated for three to six days and labeled with TRITC-phalloidin (red) and DAPI (blue) to highlight cell nuclei. (A) WT-β-TM was expressed in human myotubes and incorporated well into endogenous sarcomeric thin filaments as visualised with phalloidin (arrows). (B) The E41K-β-TM mutant induced diffuse perinuclear aggregates in myotubes (arrows). (C) The K49del-β-TM_EGFP mutant produced cytoplasmic rod-shaped filamentous actin in human myotubes. (D) The cells transfected with G53ins-β-TM mutant differentiated into myotubes, showed the integration of the mutant TM into sarcomeric structures and developed the cross-striated myofibrils in an advanced and developed state (arrow). (D’) The G53ins mutant produced diffuse cytoplasmic labeling at the far end of the transfected myotubes (arrow)_. (E) The transfection of the E122K-β-TM_EGFP construct generally resulted in the appearance of cytoplasmic rod-like structures located at the periphery of the transfected myotubes (arrow). (F) The cells transfected with N202K-β-TM_EGFP differentiated into myotubes, showed an accumulation of mutant N202K-β-TM, co-localisation with polymerised actin (arrows). Cells were imaged using a Zeiss Axio Observer microscope. Scale bar  = 10 µm.