Persistent and recyclable myosin II minifilaments drive cortical contractility in the early C. elegans embryo
- 1Institute for Biology Paris-Seine
Abstract
Non-muscle myosin II is a key regulator of cell and tissue morphogenesis, yet the cortical dynamics of myosin minifilaments in vivo remain poorly understood. Here, we combine SIM-TIRF and single-molecule TIRF microscopy to characterize the structure and dynamics of myosin minifilaments in an early developing embryo. High-temporal-resolution SIM-TIRF imaging revealed diverse minifilament behaviors, including partition-like events, long-range alignment of multiple minifilaments into collective structures we called proto-stress fibers, partial unbinding, and sequential unbinding and rebinding to the cortex. Photoconversion experiments showed that minifilaments persist as intact units after cortical unbinding, diffuse through the cytoplasm, and can be recycled over long distances rather than disassembling upon detachment. Despite these dynamic behaviors, minifilaments are predominantly stationary when bound to actin. Numerical simulations demonstrated that this static behavior is essential to sustain cortical stress within a continuously remodeling actin network. Using myosin motor-domain mutants, we further investigated the contribution of motor activity to these behaviors. Together, our results reveal that myosin minifilaments can persist as stable units while cycling between the cortex and cytoplasm, and that their predominantly static behavior when bound to actin enables sustained force generation in a continuously renewing cortical network. These findings provide new insights into myosin organization, recycling, and force generation during early embryonic development.
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BibTeX
@misc{espinoza2026persistent,
title = {{Persistent and recyclable myosin II minifilaments drive cortical contractility in the early C. elegans embryo}},
author = {K. L. Chauca Espinoza and S. K. Suman and T. Ferraro and C. Plancke and P. Mahou and E. Beaurepaire and T. Kim and F. B. ROBIN},
howpublished = {bioRxiv},
year = {2026},
month = nov,
doi = {10.64898/2026.11.04.764377},
url = {https://www.biorxiv.org/content/10.64898/2026.11.04.764377v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Persistent and recyclable myosin II minifilaments drive cortical contractility in the early C. elegans embryo
AU - K. L. Chauca Espinoza
AU - S. K. Suman
AU - T. Ferraro
AU - C. Plancke
AU - P. Mahou
AU - E. Beaurepaire
AU - T. Kim
AU - F. B. ROBIN
PY - 2026
DA - 2026/11/04
PB - bioRxiv
DO - 10.64898/2026.11.04.764377
UR - https://www.biorxiv.org/content/10.64898/2026.11.04.764377v1
AB - Non-muscle myosin II is a key regulator of cell and tissue morphogenesis, yet the cortical dynamics of myosin minifilaments in vivo remain poorly understood. Here, we combine SIM-TIRF and single-molecule TIRF microscopy to characterize the structure and dynamics of myosin minifilaments in an early developing embryo. High-temporal-resolution SIM-TIRF imaging revealed diverse minifilament behaviors, including partition-like events, long-range alignment of multiple minifilaments into collective structures we called proto-stress fibers, partial unbinding, and sequential unbinding and rebinding to the cortex. Photoconversion experiments showed that minifilaments persist as intact units after cortical unbinding, diffuse through the cytoplasm, and can be recycled over long distances rather than disassembling upon detachment. Despite these dynamic behaviors, minifilaments are predominantly stationary when bound to actin. Numerical simulations demonstrated that this static behavior is essential to sustain cortical stress within a continuously remodeling actin network. Using myosin motor-domain mutants, we further investigated the contribution of motor activity to these behaviors. Together, our results reveal that myosin minifilaments can persist as stable units while cycling between the cortex and cytoplasm, and that their predominantly static behavior when bound to actin enables sustained force generation in a continuously renewing cortical network. These findings provide new insights into myosin organization, recycling, and force generation during early embryonic development.
ER -