Influence of αvβ3 integrin on the mechanical properties and the morphology of M21 and K562 cells

Integrins play an important role in cell adhesion, morphology, migration, and many other physiological processes. The role of αvβ3 integrin has been intensively investigated in the past. However, much is still unclear about its selective role in cell contractility, adhesion, and mechanics. We looked at the influence of αvβ3 integrin on the cell mechanics of adherent M21 and suspended K562 cells with a microconstriction assay and found that the expression of αvβ3 integrin leads to higher cell stiffness and decreased fluidity in both cell lines. The disruption of the actin cytoskeleton decreased cellular stiffness in M21 (expressing α5β1 and αvβ3 integrins) and M21L (expressing only α5β1 integrin) cell lines in a similar way, but did not lead to the same baseline stiffness. The activation of integrins after the addition of Mn2+ led to higher stiffness in all observed cell lines, independent of αvβ3 integrin expression and disruption of the actin cytoskeleton. In summary, these results show that differences in stiffness/fluidity due to αvβ3 integrin expression or integrin activation by Mn2+ might not simply be explained by the coupling of integrins to actin via focal adhesions, which in turn induces changes in the actin cytoskeleton, but also by other cellular components such as the cell nucleus, intermediate filaments, or microtubules.