Protein neddylation: substrate landscape and target modulators

Neddylation is a crucial ubiquitin-like post-translational modification orchestrated by the sequential action of the NEDD8-activating enzyme (NAE), E2 conjugating enzymes (UBE2M/UBE2F), and various E3 ligases, a process dynamically reversed by deneddylases. The Cullin family, serving as the core scaffold of the largest family of E3 ubiquitin ligases (the Cullin-RING ligases, CRLs), constitutes the major physiological substrates of neddylation. Neddylation of Cullins activates CRLs, which are estimated to mediate the ubiquitination of approximately 20% of proteins degraded through the ubiquitin-proteasome system (UPS). In contrast, modification of a growing list of non-Cullin substrates predominantly influences their stability, enzymatic activity, and subcellular localization, thus participating in a broader spectrum of biological processes beyond proteolysis. Given that key components of the neddylation pathway are frequently hyperactivated in various human cancers, targeting this pathway has emerged as a promising therapeutic strategy. To date, numerous small-molecule inhibitors targeting different nodes of the pathway, including NAE, DCN1, and CSN5, have been developed. Notably, the NAE inhibitors MLN4924 and TAS4464 have advanced into clinical trials, demonstrating the therapeutic potential of neddylation inhibition. This review systematically outlines the neddylation and deneddylation cascades, provides a comprehensive summary of non-Cullin substrates and their associated regulatory enzymes, and critically evaluates the current landscape of neddylation-targeted inhibitors, highlighting opportunities for future drug development.