Relationship between rheological properties and actin filaments of single cells investigated by atomic force microscopy

Abstract

We investigated how rheological properties of single cells are spatially correlated with actin filaments (F-actin) by atomic force microscopy (AFM). This was achieved by measuring the power-law rheological properties of mouse fibroblast cells adhered on micropatterned substrate by multi-frequency force modulation AFM in the combination of the immunofluorescent observation of F-actin. We observed that G0, a scale factor of the modulus at a certain frequency, of cells was decreased as the F-actin was disrupted with a chemical treatment, showing that the spatial-averaged stiffness is associated with the F-actin formation, as observed in various cell types and microrheological methods. Interestingly, we found that G0 measured in local locations within cells displayed a negative correlation with the corresponding F-actin density. The results indicate that the local cell stiffness is not necessarily correlated with the F-actin density, but rather depending on how network structures of F-actin are formed in local regions.