Systematic profiling of DNMT3A variants reveals protein instability mediated by the DCAF8 E3 ubiquitin ligase adaptor

Clonal hematopoiesis is a prevalent age-related condition associated with greatly increased risk of hematologic malignancies. Mutations in DNA methyltransferase 3A (DNMT3A) are the most common drivers of this state and contribute to multiple types of hematologic malignancy. DNMT3A variants occur across the gene and some are associated with particular disease states, but the functional relevance and mechanisms of pathogenesis of the majority of the mutations is unknown. Here, we systematically investigated the methyltransferase activity and protein stability of 253 disease-associated DNMT3A mutations, finding that 74% were loss-of-function mutations. Nearly half of these variants exhibited reduced protein stability and, as a class, correlated with greater clonal expansion and AML development. To identify the mechanisms underlying the instability, we conducted a CRISPR screen and uncovered regulated destruction of DNMT3A mediated by the DCAF8 E3 ubiquitin ligase adaptor. We establish a new paradigm to classify novel variants that has prognostic and therapeutic significance for patients with hematologic disease. Overall design: Examination of WGBS and RNAseq under proteasome inhibitor treatment in patient-derived LCLs.