O-GlcNAcylation of Focal Adhesion Kinase Regulates Cell Adhesion, Migration, and Proliferation via the FAK/AKT Pathway

Focal Adhesion Kinase (FAK) is a non-receptor tyrosine kinase pivotal in cellular signal transduction, regulating cell adhesion, migration, growth, and survival. However, the regulatory mechanisms of FAK during tumorigenesis and progression still need to be fully understood. Our previous study demonstrated that <i>O</i>-GlcNAcylation regulates integrin-mediated cell adhesion. To further elucidate the underlying molecular mechanism, we focused on FAK in this study and purified it from 293T cells. Using liquid chromatography-mass spectrometry (LC-MS/MS), we identified the <i>O</i>-GlcNAcylation of FAK at Ser708, Thr739, and Ser886. Compared with wild-type FAK expressed in <i>FAK</i>-knockout 293T cells, the FAK mutant, in which Ser708, Thr739, and Ser886 were replaced with Ala, exhibited lower phosphorylation levels of Tyr397 and AKT. Cell proliferation and migration, assessed through MTT and wound healing assays, were significantly suppressed in the FAK mutant cells compared to the wild-type FAK cells. Additionally, the interaction among FAK, paxillin, and talin was enhanced, and cell adhesion was increased in the mutant cells. These data indicate that specific <i>O</i>-GlcNAcylation of FAK plays a critical regulatory role in integrin-mediated cell adhesion and migration. This further supports the idea that <i>O</i>-GlcNAcylation is essential for tumorigenesis and progression and that targeting the <i>O</i>-GlcNAcylation of FAK could offer a promising therapeutic strategy for cancer treatment.