Role of DLC1 in Regulating Cellular and Focal Adhesion Dynamics

Deleted in Liver Cancer‐1 (DLC1) is a RhoGTPase‐activating protein that is down‐regulated in a number of cancers. It specifically acts on RhoA and to some extent Cdc42, but has no discernible effect on Rac1 activity. DLC1 has been shown to localize to the focal adhesions and its absence leads to enhanced cell migration. However, its role at the focal adhesions and its subsequent effect on cell migration is still unclear. Using immunofluorescence techniques, Total Internal Reflection Fluorescence Microscopy (TIRFM) and quantitative image analysis we examined the effect of DLC1 on cell migration and cell spreading and determined its localization and dynamics at focal complexes, focal adhesions and fibrillar adhesions to understand how these cellular dynamics are affected. We found that DLC1 inhibits cell spreading in a RhoA‐dependent, substrate‐independent manner whereas it inhibits cell migration in a RhoA‐independent manner. DLC1 also localizes to all three adhesion types, with a specific spatial distribution in the focal adhesions during early and late stages of cell spreading when compared to focal adhesion proteins such as paxillin and Focal Adhesion Kinase (FAK). In summary, DLC1 regulates cellular dynamics by its down‐regulation of RhoA as well as its effects on focal adhesion dynamics. Supported by Mechanobiology Institute and Ministry of Education, Singapore (Academic Research Fund T208A3121)