SETD8-mediated mono-methylation of YAP at K76 promotes K48-linked polyubiquitination and degradation to suppress colorectal cancer.

Yes-associated protein (YAP), a key effector of the Hippo pathway, plays a well-established role in colorectal cancer (CRC). However, the functional relevance of site-specific post-translational modifications (PTMs) in YAP, particularly methylation, remains insufficiently explored. SET-domain-containing protein 8 (SETD8), the sole mono-methyltransferase for histone 4 lysine 20 (H4K20), is implicated in various cancers, yet its biological function and underlying mechanisms in CRC are elusive. While SETD8 is primarily known for its histone methylation activity, its capacity to modify non-histone proteins, such as YAP, remains largely unexplored. This study aimed to demonstrate that SETD8 exerted a tumor-suppressive effect on CRC by inhibiting YAP protein expression. Mechanistically, SETD8 physically interacts with YAP to catalyze mono-methylation at lysine 76 (K76me). This modification enhances the interaction between YAP and the E3 ubiquitin ligase RING finger protein 31 (RNF31), promoting YAP K48-linked polyubiquitination and subsequent proteasomal degradation. Clinically, patients with CRC and high SETD8 expression, including elevated YAP K76me levels, exhibited favorable pathological grading and improved prognosis. Collectively, our findings identify a novel SETD8-YAP K76me regulatory axis that restricts CRC progression, suggesting that targeting this axis may represent a promising therapeutic strategy.