OGFOD1, a Novel Modulator of Eukaryotic Translation Initiation Factor 2α Phosphorylation and the Cellular Response to Stress

Cells possess mechanisms that permit survival and recovery from stress, several of which regulate the phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2 alpha). We identified the human OGFOD1 protein as a novel stress granule component that regulates the phosphorylation of eIF2 alpha and the resumption of translation in cells recovering from arsenite-induced stress. Coimmunoprecipitation studies revealed that OGFOD1 associates with a small subset of stress granule proteins (G3BP1, USP10, Caprin1, and YB-1) and the ribosome in both unstressed and stressed cells. Overexpression of OGFOD1 led to increased abundance of phosphorylated eIF2 alpha, both in unstressed cells and in cells exposed to arsenite-induced stress, and to accelerated apoptosis during stress. Conversely, knockdown of OGFOD1 resulted in smaller amounts of phosphorylated eIF2 alpha and a faster accumulation of polyribosomes in cells recovering from stress. Finally, OGFOD1 interacted with both eIF2 alpha and the eIF2 alpha kinase heme-regulated inhibitor (HRI), which was identified as a novel stress granule resident. These findings argue that OGFOD1 plays important proapoptotic roles in the regulation of translation and HRI-mediated phosphorylation of eIF2 alpha in cells subjected to arsenite-induced stress.