Identification of GRIM-19, a novel cell death-regulatory gene induced by the interferon-β and retinoic acid combination, using a genetic approach

We show here that the combination of interferon-beta (TFN-beta) and all-trans-retinoic acid (RA) induces the death of tumor cells. To understand the molecular basis for synergistic growth-suppressive action and to identify the gene products that participate in this process, me have employed an antisense knock-out technique. This approach permits the isolation of cell death-associated genes based on their selective inactivation by over-expression of antisense cDNAs, Because the antisense mRNA inactivates gene expression of death-specific genes, transfected cells survive in the presence death inducers. Several Genes associated with Retinoid-IFN-induced Mortality (GRIM) were identified using this approach. Here me report, the isolation of a novel GRIM gene, GRIM-19. This 552-base pair cDNA encodes a 16-kDa protein. Antisense expression of GRIM-19 confers a strong resistance against IFN/RA-induced death by reducing the intracellular levels of GRIM-19 protein. Overexpression of GRIM-19 enhances cell death in response to IFN/RA. GRIM-IS is primarily a nuclear protein whose expression is induced by the IFN/RA combination. Together, our studies identify a novel cell death-regulatory molecule.