Micromechanical coupling between cell surface receptors and RGD peptides

Area of Science:

• Cell Biology
• Biophysics
• Biochemistry

Background:

• Cell adhesion, migration, and growth are mediated by integrins, which connect cells to the extracellular matrix (ECM).
• The cytoplasmic recruitment of molecules to integrins upon ECM contact is known, but its effect on integrin-ECM binding affinity is unclear.

Purpose of the Study:

• To investigate whether intracellular signaling molecules recruited to integrins enhance the binding affinity between the ECM and cell surface receptors.
• To explore the relationship between cell stiffness, receptor-ligand unbinding lifetime, and cytoskeletal integrity.

Main Methods:

• Utilized soft microneedles coated with Arg-Gly-Asp (RGD) peptides to apply localized shear stress to HeLa cell surfaces.
• Measured cell stiffness and the collective unbinding lifetime of surface receptors (integrins) to RGD peptides.
• Assessed the dependence of these parameters on pre-shear contact duration, shear rate, and actin filament network integrity.

Main Results:

• Both cell stiffness and the collective integrin-RGD unbinding lifetime increased with pre-shear contact duration and shear rate.
• These mechanical properties were critically dependent on the integrity of the actin filament network.
• Results support a positive feedback model where initial RGD-mediated recruitment enhances integrin-ECM interactions.

Conclusions:

• Intracellular recruitment of cytoskeletal proteins to integrins, triggered by ECM contact, enhances the mechanical stability of the integrin-ECM bond.
• This positive feedback mechanism plays a crucial role in regulating cell adhesion and mechanical responses.
• The findings provide insights into the dynamic regulation of cell-matrix interactions.