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Updated: Oct 30, 2025
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Sarcomere Shortening of Pluripotent Stem Cell-Derived Cardiomyocytes using Fluorescent-Tagged Sarcomere Proteins.
Published on: March 3, 2021
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Molecular-scale visualization of sarcomere contraction within native cardiomyocytes
Laura Burbaum1, Jonathan Schneider2, Sarah Scholze3
1Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany.
Nature Communications
|July 3, 2021
Summary
This study visualizes muscle contraction at the molecular level, revealing how actin and myosin filaments slide past each other. It provides direct evidence for thin filament sliding in sarcomeres, enhancing our understanding of muscle contractility.
Area of Science:
- Muscle physiology
- Molecular biology
- Biophysics
Background:
- Sarcomeres are the fundamental contractile units of striated muscle.
- Muscle contraction relies on cross-bridge interactions between actin and myosin filaments.
- Direct visualization of the molecular mechanisms of sarcomere contractility has been limited.
Purpose of the Study:
- To visualize the molecular architecture of sarcomere contraction in situ.
- To provide direct evidence for thin filament sliding during muscle contraction.
- To understand thin filament activation and actomyosin interactions in an unperturbed cellular environment.
Main Methods:
- In situ cryo-electron tomography was used to image frozen-hydrated neonatal rat cardiomyocytes.
- Subtomogram averaging was employed for structural assessment of actin polarity.
Main Results:
- The hexagonal lattice of thick filaments is established early in neonatal cardiomyocytes.
- Thin filaments exhibit overlapping arrays of opposite polarity in the sarcomere center during activation.
- Direct evidence for thin filament sliding during muscle contraction was obtained.
Conclusions:
- The study provides unprecedented direct visualization of sarcomere contraction at the molecular level.
- Findings elucidate the structural basis of thin filament sliding and actomyosin interactions.
- This approach offers a foundation for future studies on muscle contractility within native cellular contexts.
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