Figure 5.

Nanoneedle degradation recovers mechanoresponsive cell behaviors. (A) SEM images show nN degradation after 48 h in culture. Scale bars = 1 μm, 2 μm inset. (B) Cell phenotype is restored on degraded nN as compared to flat control substrates at 6 h. Cells exhibit a spread actin cytoskeleton (green: phalloidin, scale bars = 50 μm), dense staining of vinculin-rich focal adhesions (red: vinculin, cyan: DAPI, scale bars = 25 μm), nuclear localization of YAP (green, scale bars = 50 μm), and an unimpinged nucleus (magenta: lamin A, cyan: DAPI, scale bars = 5 μm). (C) Image analysis shows a partial return of YAP localization to the nucleus and (D) increased focal adhesion (vinculin) density (box plots, minimum/maximum). (E) Schematic representation of the cell−nN interaction. Cells on flat substrates display firm focal adhesions, which allow for generation of intracellular tension, yielding YAP nuclear localization and subsequent transcriptional activity, and a uniform nuclear lamina composition. nN interfacing limits focal adhesion formation and maturation, directly stimulates actin ring formation, and results in segregation of lamin A and B at the nucleus. Furthermore, lamin A is downregulated at the protein level but upregulated at the gene level in response to interactions with nN.