Key result
During myofibrillogenesis in rat neonatal cardiomyocytes, myosin filaments assemble laterally onto premyofibrils, proceeding stepwise along the axial direction to form mature Z-disks.
This study demonstrates that myosin filaments assemble laterally onto premyofibrils during sarcomeric addition in live neonatal cardiomyocytes, playing a role in Z-disk formation and sarcomeric alignment.
No immediate clinical implications; hypothesis-generating for sarcomere assembly mechanisms in mammalian cardiomyocytes.
AIMS: Understanding myofibrillogenesis is essential for elucidating heart muscle formation, development, and remodelling in response to physiological stimulation. Here, we report the dynamic assembly process of contractile myosin filaments onto myofibrils in a live cardiomyocyte culture during myofibrillogenesis. METHODS AND RESULTS: Utilizing a custom-built, two-photon excitation fluorescence and second harmonic generation imaging system equipped with an on-stage incubator, we observed new sarcomere additions in rat neonatal cardiomyocytes during 10 h of on-stage incubation. The new sarcomere additions occurred at the side of existing myofibrils, where we observed mature myofibrils acting as templates, or at the interstice of several separated myofibrils. CONCLUSIONS: During sarcomeric addition, myosin filaments are assembled onto the premyofibril laterally. This lateral addition, which proceeds stepwise along the axial direction, plays an important role in the accumulation of Z-bodies to form mature Z-disks and in the regulation of sarcomeric alignment during maturation.
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Liu et al. (2012) studied Myofibrillogenesis. TPEF-SHG microscopy observation was evaluated on Dynamic assembly process of contractile myosin filaments onto myofibrils. During myofibrillogenesis in rat neonatal cardiomyocytes, myosin filaments assemble laterally onto premyofibrils, proceeding stepwise along the axial direction to form mature Z-disks.
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