RT Journal Article SR Electronic T1 Cell Mechanosensing and Avoidance of Strain Gradients JF bioRxiv FD Cold Spring Harbor Laboratory SP 095976 DO 10.1101/095976 A1 Sophie Chagnon-Lessard A1 Hubert Jean-Ruel A1 Michel Godin A1 Andrew E. Pelling YR 2017 UL http://biorxiv.org/content/early/2017/01/25/095976.abstract AB INSIGHT, INNOVATION, INTEGRATION In the body, mechanical stress arising due to movement exposes cells to complex and anisotropic strains and strain gradients. Employing an innovative microfabricated device, we have uncovered how strain gradients can act as an important biological signal. Our device enables the systematic investigation of strain and strain gradient directions in a single membrane. Decoupling these two pieces of mechanical information provides critical new evidence that cells are able to spatially integrate and respond to both physical cues. Moreover, cells specifically respond to these two simultaneous physical cues by exhibiting a clear strain gradient avoidance behaviour. This work reveals new insights into how strain gradients play a key role in guiding the long-range organization in populations of living cells.ABSTRACT The strain-induced reorientation response of cyclically stretched cells has been well characterized in uniform strain fields. In the present study, we comprehensively analyse the behaviour of human fibroblasts subjected to a highly non-uniform strain field within a polymethylsiloxane microdevice. We first demonstrate a strong correlation between the strain amplitude and the degree of cell alignment perpendicular to the principal strain direction (stretching avoidance). More importantly, our results indicate that the strain gradient amplitude and direction also regulate cell reorientation through a coordinated gradient avoidance response. We provide critical new evidence that strain gradient is a key physical cue that can guide cell organization. Specifically, our work suggests that cells are able to pinpoint the location under the cell of multiple physical cues and integrate this information (strain and strain gradient amplitudes and directions), resulting in a coordinated response. To gain insight into the underlying mechanosensing processes, we studied focal adhesion reorganization and the effect of modulating myosin-II contractility. The extracted focal adhesion orientation distributions are similar to those obtained for the cell bodies, and their density is increased by the presence of stretching forces. Moreover, it was found that the myosin-II activity promoter calyculin-A has little effect on the cellular response, while the inhibitor blebbistatin suppresses cell and focal adhesion alignment and reduces focal adhesion density. These results confirm that similar internal structures involved in sensing and responding to strain direction and amplitude are also key players in strain gradient mechanosensing and avoidance.