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A mechanical function of myosin II in cell motility
1Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.
Journal of Cell Science
|January 1, 1995
Summary
Myosin II is crucial for amoeboid locomotion, enabling cell retraction from surfaces. Myosin II mutant cells show impaired crawling, especially on sticky substrates, highlighting its role in cell detachment and forward movement.
Area of Science:
- Cell Biology
- Biophysics
- Cytoskeletal Dynamics
Background:
- Amoeboid locomotion is essential for cellular functions.
- Myosin II's role in cell motility is not fully understood.
- Dictyostelium discoideum serves as a model organism for studying cell migration.
Purpose of the Study:
- To investigate the contribution of myosin II to amoeboid locomotion in Dictyostelium.
- To determine how myosin II affects cell retraction from surfaces with varying adhesivity.
- To elucidate the mechanism of cell shape regulation during locomotion.
Main Methods:
- Comparative analysis of wild-type and myosin II null mutant Dictyostelium cell speeds on different substratum adhesivities.
- Interference reflection microscopy to visualize cell-substratum interactions and contractions.
- Assessment of cell elongation and retraction dynamics.
Main Results:
- Myosin II null mutant cells exhibited significantly reduced speed on highly adhesive surfaces compared to wild-type cells.
- Myosin II-dependent contractions were observed in wild-type cells but absent in null mutants, indicating a role in retraction.
- Despite retraction defects, myosin II null mutant cells maintained shape on sticky surfaces, suggesting cytoskeletal tension involvement.
Conclusions:
- Myosin II is essential for efficient amoeboid locomotion, particularly for rear-edge retraction from adhesive substrates.
- Contractile forces generated by myosin II balance adhesive forces, facilitating cell detachment and forward movement.
- Cytoskeletal tension may provide a compensatory mechanism for retraction and cell division in myosin II deficient cells.
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