Gp93 safeguards tissue homeostasis by preventing ROS-JNK-mediated apoptosis.

Reactive oxygen species (ROS) play a pivotal role in maintaining tissue homeostasis, yet their overabundance can impair normal cellular functions, induce cell death, and potentially lead to neurodegenerative disorders. This study identifies Drosophila Glycoprotein 93 (Gp93) as a crucial factor that safeguards tissue homeostasis and preserves normal neuronal functions by preventing ROS-induced, JNK-dependent apoptotic cell death. Firstly, loss of Gp93 induces JNK-dependent apoptosis primarily through the induction of ROS. Secondary, neuro-specific depletion of Gp93 results in ROS-JNK-mediated neurodegeneration. Thirdly, overexpression of Gp93 effectively curtails oxidative stress and neurodegeneration caused by paraquat exposure or the aging process. Furthermore, these functions of Gp93 can be substituted by its human ortholog, HSP90B1. Lastly, depletion of HSP90B1 in cultured human cells triggers ROS production, JNK activation, and apoptosis. Thus, this study not only unveils a novel physiological function of Gp93, but also provides valuable insights for understanding the physiological and pathological functions of human HSP90B1.