Nanoscale curvature of the plasma membrane regulates mechanoadaptation through nuclear deformation and rupture
Nuclear translocation of the transcription regulatory proteins YAP and TAZ is a critical readout of cellular mechanotransduction. Recent experiments have demonstrated that cells on substrates with well-defined nanotopographies demonstrate mechanoadaptation through a multitude of effects - increased integrin endocytosis as a function of nanopillar curvature, increased local actin assembly on nanopillars but decreased global cytoskeletal stiffness, and enhanced nuclear deformation. How do cells respond to local nanotopo-graphical cues and integrate their responses across multiple length scales? This question is addressed using a biophysical model that incorporates plasma membrane (PM) curvature-dependent endocytosis, PM curvature-sensitive actin assembly, and stretch-induced opening of nuclear pore complexes (NPCs) in the nuclear envelope (NE). This model recapitulates lower levels of global cytoskeletal assembly on nanopillar substrates, which can be partially compensated for by local actin assembly and NE indentation, leading to enhanced YAP/TAZ transport through stretched NPCs. Using cell shapes informed by electron micrographs and fluorescence images, the model predicts lamin A and F-actin localization around nanopillars, in good agreement with experimental measurements. Finally, simulations predict nuclear accumulation of YAP/TAZ following rupture of the NE and this is validated by experiments. Overall, this study indicates that nanotopography tunes mechanoadaptation through both positive and negative feedback on mechanotransduction. Table of Contents O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=185 SRC="FIGDIR/small/619165v2_ufig1.gif" ALT="Figure 1"> View larger version (84K): org.highwire.dtl.DTLVardef@ec6d5aorg.highwire.dtl.DTLVardef@1ff6ec2org.highwire.dtl.DTLVardef@c09f46org.highwire.dtl.DTLVardef@18df50_HPS_FORMAT_FIGEXP M_FIG C_FIG This study uses experiments and biophysical modeling to examine the response and adaptation of cells to nanoscale topography of surfaces. It is shown that cytoskeletal assembly and nuclear localization of transcription regulatory factors such as YAP/TAZ can be tuned by nanoscale membrane curvature and nuclear deformation and rupture due to substrate nanotopography.