Crispr-Cas9 screen identifies potential novel regulators of CD8+ T cell dysfunction.

Abstract CD8+ T cells directly target and kill cancer cells and are required for effective antitumor immunity. However, CD8+ T cells may become dysfunctional when exposed to chronic antigen stimulation during cancer. Dysfunction is characterized by reduced proliferation, increased expression of inhibitory receptors, and impaired effector function, yet the genetic mechanisms controlling dysfunction remain poorly understood. To address this gap, we have developed an ex vivo restimulation model that recapitulates features of CD8+ T cell dysfunction seen within the tumor microenvironment. By coupling this system with genome-wide CRISPR-Cas9 loss of function screening, we have identified eIF4G2, a non-canonical protein translation factor, which may play a novel role in the progression of CD8+ T cells to a dysfunctional state. Deletion of eIF4G2 restored CD8+ T cell survival and proliferation during chronic restimulation conditions in vitro. Transcriptomic and flow cytometric analyses revealed that eIF4G2 controls expression of genes contributing to oxidative stress and a dysfunctional phenotype in vitro. Future studies will focus on characterizing the mechanistic and functional roles of this protein translation factor in vivo, as well as translating this model to primary human CD8+ T cells. In summary, we have uncovered eIF4G2 as a novel potential regulator of CD8+ T cell dysfunction and targeting eIF4G2 may improve antitumor immunity and immunotherapy efficacy.