The <i>Drosophila</i> ZER1 homolog interacts with ref(2)P to regulate autophagy and Keap1-cnc/NFE2L2/Nrf2-mediated oxidative stress

The ubiquitin-proteasome system (UPS) and macroautophagy/autophagy are two major pathways for maintaining cellular protein homeostasis. Increasing evidence has highlighted the complex interactions and crosstalk between these pathways; however, the specific molecules and mechanisms mediating the interplay between the UPS and autophagy are still not fully elucidated. In this study, we discovered that knocking down the <i>Drosophila</i> Cul2 (Cullin 2)-RING ubiquitin ligase complex adaptor CG12084/DmZer1 impedes autophagy and autophagic flux. DmZer1 interacts with the <i>Drosophila</i> SQSTM1/p62 homolog ref(2)P, promoting its association with ubiquitinated proteins and degradation. ref(2)P is a crucial player in regulating autophagy and the Keap1-cnc/NFE2L2 pathway-mediated antioxidant response. Knockdown of DmZer1 leads to the formation of ref(2)P bodies, which sequester Keap1 and promote cnc/NFE2L2-mediated antioxidant responses under oxidative stress conditions. These findings reveal the pivotal role of DmZer1 in regulating autophagy and the ref(2)P-Keap1-cnc/NFE2L2-mediated oxidative stress response.<b>Abbreviations</b>: ARM: armadillo-like domain; ATG: autophagy related; BTZ: bortezomib; CL1-GFP: GFP fused with a CL1 degron; cnc: cap-n-collar; co-IP: co-immunoprecipitation; CRL2: Cullin 2-RING E3 ubiquitin ligase complex; CQ: chloroquine; CUL2/Cul2: cullin 2; EloB: Elongin B; EloC: Elongin C; <i>esg</i>: escargot; ISCs: intestinal stem cells; KEAP1: kelch like ECH associated protein 1; LIR: LC3-interacting region; LLPS: liquid-liquid phase separation; LRR: leucine-rich repeat; NFE2L2/Nrf2: NFE2 like bZIP transcription factor 2; p-H3: phospho-histone H3; PQ: paraquat; ref(2)P: refractory to sigma P; SQSTM1/p62: sequestosome 1; UBA: ubiquitin-associated; UPS: ubiquitin-proteasome system; VHL: von Hippel-Lindau tumor suppressor; ZER1: zyg-11 related cell cycle regulator.