Viscoelasticity of single cells-from subcellular to cellular level

Area of Science:

• Cellular mechanics
• Biophysics
• Cytoskeletal dynamics

Background:

• Understanding cellular structures and processes is crucial for deciphering cell mechanics.
• The interplay between actin and microtubules is key to cell stabilization and migration.
• Existing methods often lack the resolution to probe complex intracellular dynamics.

Purpose of the Study:

• To provide insights into cellular structures and processes by measuring viscoelastic impedances.
• To introduce a mechanical cell model explaining self-stabilization via actin-microtubule crosstalk.
• To explore the mechanisms driving cell movement and migration.

Main Methods:

• Colloidal bead microrheometry to measure viscoelastic impedances of the cell envelope and cytoplasm.
• Development of a mechanical cell model for studying self-stabilization.
• Traction force microscopy and deformation field mapping for force and impedance measurements.
• Utilizing colloidal beads as phantom endosomes to evaluate cytoplasmic properties.
• Biomimetic experiments based on percolation theory for actin network analysis.

Main Results:

• A mechanical cell model elucidates self-stabilization through actin-microtubule crosstalk.
• Cellular movements are driven by solitary actin gelatin waves (SAGW) generated by protein recruitment.
• Actin-microtubule crosstalk, mediated by IQGAP, guides cell migration polarization.
• Viscoelastic impedances of the cell envelope and cytoplasmic properties were quantitatively measured.
• Local transport forces, viscosities, and motion lifetimes along microtubules were determined.

Conclusions:

• Colloidal bead microrheometry offers a powerful approach to quantitatively assess cellular mechanical properties.
• Actin-microtubule interactions and protein dynamics are fundamental to cell mechanics and migration.
• The study provides a framework for understanding the active, dynamic nature of the cytoplasm and cytoskeleton.