Abstract
Modulation of protein synthesis according to the physiological cues is maintained through tight control of Eukaryotic Elongation Factor 2 (eEF2), whose unique translocase activity is essential for cell viability. Phosphorylation of eEF2 at its Thr56 residue inactivates this function in translation. In our previous study we reported a novel mode of post-translational modification that promotes higher efficiency in T56 phosphorylation. Cyclin A/CDK2-mediated phosphorylation of eEF2 at the S595 residue is required for more potent phosphorylation at the Thr56, suggesting CDK2 takes a role in robust suppression of protein synthesis. In the current study, we analyzed the cell cycle, proliferation, cell death, migration, colony formation, autophagy, and response to Cisplatin properties of the point-mutant variant of HCT116 cells that express the CDK2 mutant (S595A-eEF2) of eEF2. The knocked in S595A mutation resulted in decreased levels of T56 phosphorylation of eEF2, which appears to have similar biological consequences to other experimental manipulations such as silencing the activity of the kinase for the Thr56 residue, eEF2 Kinase (eEF2K). Our findings indicate that interfering with the inhibition of eEF2 results in elevated protein synthesis in HCT116 cells and is associated with the progression of malignancy in the colorectal cancer cell line, where eEF2K activity could provide a tumor suppressive role.