Mitochondrial Network Configuration Influences Sarcomere and Myosin Filament Structure in Striated Muscles

Abstract

Sustained muscle contraction occurs through interactions between actin and myosin filaments within sarcomeres and requires a constant supply of adenosine triphosphate (ATP) from nearby mitochondria. However, it remains unclear how different physical configurations between sarcomeres and mitochondria alter the energetic support for contractile function. Here, we show that sarcomere cross-sectional area (CSA) varies along its length in a cell type-dependent manner where the reduction in Z-disk CSA relative to the sarcomere center is closely coordinated with mitochondrial network configuration. Further, we find myosin filaments near the sarcomere periphery are curved relative to interior filaments with greater curvature for filaments near mitochondria compared to the sarcoplasmic reticulum. Finally, we demonstrate myosin filament lattice spacing is smaller at filament ends than filament centers in a cell type-dependent manner. These data suggest that both sarcomere structure and myofilament interactions are influenced by the location and orientation of mitochondria within a muscle cell.

Sarcomere maturation: function acquisition, molecular mechanism, and interplay with other organelles

“…Mitochondria are positioned between lined myofibrils and mechanically elongated by the myofibrils. The geometry of mitochondria also influences the interaction between sarcomeres and thick filaments within the muscle cell [172]. Myofibril and mitochondria morphogenesis are intimately linked in Drosophila muscles.…”