Protein lysine methyltransferases (PKMTs, HMTs) are an important target class for modulation to regulate gene expression, cell differentiation, and organismal development. Polycomb repressive complex 2 (PRC2) that catalyzes methylation of H3K27 contains either the enzymatic subunit EZH2 or EZH1. Lysine Methyltransferases EZH2 and EZH1 are highly homologous and share 76% sequence identity overall. And the 96% sequence lies in their respective SET domains. Despite their high sequence identity, EZH2 and EZH1 are not functionally redundant and have different expression patterns. While EZH2 is only found in actively dividing cells, EZH1 is found in both dividing and non-dividing cells. In this study, UNC1999 is the orally bioavailable chemical probe of EZH2 and EZH1. UNC1999 is highly potent and selective for EZH2 wild-type and Y641 mutant enzymes as well as EZH1 over a broad range of epigenetic and non-epigenetic targets. UNC2399, a biotinylated UNC1999, is a selective EZH2 degrader.

UNC2399 (1-1000 nM) displays high in vitro potency (IC50=17±2 nM) in the EZH2 radioactive biochemical assay. It also (100 μM) enriches EZH2 from HEK293T cell lysates. UNC2399 is a useful tool for enriching EZH2 from cell lysates and lays the groundwork for future use of UNC2399 in chemoproteomics studies.

In summary, UNC2399, a biotinylated UNC1999, is a selective EZH2 degrader. It maintains high in vitro potency for EZH2 with an  IC50 of 17 nM. UNC2399 enriches EZH2 in pull-down studies and a UNC1999-dye conjugate (UNC2239) for co-localization studies with EZH2 in live cells.  UNC2399 is a useful tool for the biomedical community to investigate the role of EZH2 in health and disease.


Konze KD, et al.  ACS Chem Biol. 2013;8(6):1324-1334.