Stress-induced NEDDylation promotes cytosolic protein aggregation through HDAC6 in a p62-dependent manner

Stress-coupled NEDDylation potentially regulates the aggregation of nuclear proteins, which could protect the nuclear ubiquitin-proteasome system from proteotoxic stress. However, it remains unclear how NEDDylation controls protein-aggregation responses to diverse stress conditions. Here, we identified HDAC6 as a direct NEDD8-binding partner that regulates the formation of aggresome-like bodies (ALBs) containing NEDDylated cytosolic protein aggregates during ubiquitin stress. HDAC6 colocalizes with stress-induced ALBs, and HDAC6 inhibition suppresses ALBs formation, but not stress-induced NEDDylation, suggesting that HDAC6 carries NEDDylated-proteins to generate ALBs. Then, we monitored the ALBs-associated proteostasis network and found that p62 directly controls ALBs formation as an acceptor of NEDDylated cytosolic aggregates. Interestingly, we also observed that ALBs are highly condensed in chloroquine-treated cells with impaired autophagic flux, indicating that ALBs rely on autophagy. Collectively, our data suggest that NEDD8, HDAC6, and p62 are involved in the management of proteotoxic stress by forming cytosolic ALBs coupled to the aggresome-autophagy flux.