Probing transmembrane mechanical coupling and cytomechanics using magnetic twisting cytometry

Area of Science:

• Cellular biomechanics
• Molecular mechanotransduction
• Biophysics

Background:

• Cells sense and respond to mechanical forces through transmembrane receptors.
• Integrins are key mediators of cell-matrix interactions and force transmission.
• Cytoskeletal dynamics are crucial for cell shape, function, and response to mechanical stimuli.

Purpose of the Study:

• To investigate the role of different transmembrane receptors in mechanical force transfer.
• To characterize the relationship between applied stress, cytoskeletal stiffness, and cell shape.
• To assess the versatility of magnetic twisting cytometry for studying cell mechanics.

Main Methods:

• Magnetic twisting cytometry (MTC) to apply controlled forces to cell surface receptors.
• Use of ligand-coated ferromagnetic microbeads to engage specific receptors.
• Measurement of cellular mechanical response and cytoskeletal stiffness in living cells.

Main Results:

• Beta 1 integrins, but not scavenger receptors, mediate force transfer to the cytoskeleton.
• Cytoskeletal stiffness increases linearly with applied stress to integrins, with varying slopes based on cell shape.
• Different integrins and other receptors exhibit distinct force-transfer capabilities.
• Linear stiffening response is conserved across various cell types.
• Cell spreading and retraction dynamics correlate with cytoskeletal stiffness changes.

Conclusions:

• Magnetic twisting cytometry is a powerful tool for analyzing transmembrane mechanical coupling to the cytoskeleton.
• Receptor type and cell shape significantly modulate mechanical signal transmission.
• Dynamic cell shape changes are tightly linked to cytoskeletal stiffness regulation.