Cellular Responses to Nanoscale Topography Mediated Through the RhoA/ROCK Pathway

Nanotopography exhibits strong effects on cellular properties such as cytoskeletal organization and endocytosis. Responses to topographical cues can propagate into cell-scale characteristics like cortical stiffness as well as systemic effects like inflammation and implant rejection; however, the biological pathways governing these effects remain comparatively unknown. Here we show how the RhoA/ROCK pathway can regulate responses to nanotopographical features vis-à-vis cellular tension. 2D arrays of hemispherical gold nanoparticles are combined with epithelial cells to determine how up- and down-regulating RhoA activity influences cellular responses. It is found that higher RhoA activity correlates with increased tension and decreased membrane conformality, actin reorganization, and endocytosis. Also, increased tension produces large focal adhesions in cells not typically observed from substrate patterns. Conversely, reducing tension by lowering RhoA activity results in increased membrane conformality around the nanoparticles as well as actin and endocytosis colocalization with nanoparticle sites. This study provides a critical connection between biomolecular regulators of cell mechanics, in particular RhoA, and cellular responses to nanoscale topographical features.