A novel FRET analysis method for tension dynamics in a single actin stress fiber: Application to MC3T3-E1 cells during movement on a substrate

Actin stress fibers (SFs) generate tension and play crucial roles in multiple cellular functions. However, it remains unclear how the tension changes in a single SF during cell movement on a substrate. In this study, we developed a new method to analyze the change in tension in a single SF in a cell with a Förster resonance energy transfer (FRET)-based tension sensor. With this new method, we have evaluated the relationship between the movement of SFs in the bottom of an MC3T3-E1 cell and their FRET ratio change, i.e., the tension change, for the first time to our knowledge. We found that the tension in SFs decreases when they rotate. The tension had no significant correlation with their translation nor with their length change.