Decoupling of Apoptosis from Activation of the ER Stress Response by the Metallopeptidase .

Endoplasmic reticulum (ER) stress-induced apoptosis is a primary cause and modifier of degeneration in a number of genetic disorders. Understanding how genetic variation influences the ER stress response and subsequent activation of apoptosis could improve individualized therapies and predictions of outcomes for patients. In this study, we find that the uncharacterized, membrane-bound metallopeptidase in , which we rename as (), plays a role in modifying ER stress-induced apoptosis. We demonstrate that loss of reduces apoptosis and degeneration in the model of ER stress through the JNK signaling cascade. This effect on apoptosis occurs without altering the activation of the unfolded protein response (IRE1 and PERK), suggesting that the beneficial prosurvival effects of this response are intact. Furthermore, we show that functions epistatically upstream of -a known JNK-activated proapoptotic factor in this model of ER stress. We demonstrate that is not only a modifier of this particular model, but affects the general tolerance to ER stress, including ER stress-induced apoptosis. Finally, we present evidence of Superdeath localization to the ER membrane. While similar in sequence to a number of human metallopeptidases found in the plasma membrane and ER membrane, its localization suggests that is orthologous to in humans. Together, this study provides evidence that is a link between stress in the ER and activation of cytosolic apoptotic pathways.