Analysis of cell mechanics in single vinculin-deficient cells using a magnetic tweezer

A magnetic tweezer was constructed to apply controlled tensional forces (10 pN to greater than 1 nN) to transmembrane receptors via bound ligand-coate d microbeads while optically measuring lateral bead displacements within in dividual cells. Use of this system with wild-type F9 embryonic carcinoma ce lls and cells from a vinculin knockout mouse F9 Vin (-/-) revealed much lar ger differences in the stiffness of the transmembrane integrin linkages to the cytoskeleton than previously reported using related techniques that mea sured average mechanical properties of large cell populations. The mechanic al properties measured varied widely among cells, exhibiting an approximate ly log-normal distribution. The median lateral bead displacement was a-fold larger in F9 Vin (-/-) cells compared to wild-type cells whereas the arith metic mean displacement only increased by 37%. We conclude that vinculin se rves a greater mechanical role in cells than previously reported and that t his magnetic tweezer device may be useful for probing the molecular basis o f cell mechanics within single cells. (C) 2000 Academic Press.