Discovery of the First-in-Class G9a/GLP Covalent Inhibitors

• Published in: Journal of medicinal chemistry 2022-08, Vol.65 (15), p.10506-10522
• Main Authors: Park, Kwang-Su, Xiong, Yan, Yim, Hyerin, Velez, Julia, Babault, Nicolas, Kumar, Prashasti, Liu, Jing, Jin, Jian
• Format: Article
• Language: English
• Subjects: Crystallography, X-Ray; Histone-Lysine N-Methyltransferase - metabolism; Humans; Lysine - metabolism; Mass Spectrometry
• ISSN: 0022-2623; 1520-4804
• DOI: 10.1021/acs.jmedchem.2c00652

The highly homologous protein lysine methyltransferases G9a and GLP, which catalyze mono- and dimethylation of histone H3 lysine 9 (H3K9), have been implicated in various human diseases. To investigate functions of G9a and GLP in human diseases, we and others reported several noncovalent reversible small-molecule inhibitors of G9a and GLP. Here, we report the discovery of the first-in-class G9a/GLP covalent irreversible inhibitors, 1 and 8 (MS8511), by targeting a cysteine residue at the substrate binding site. We characterized these covalent inhibitors in enzymatic, mass spectrometry based and cellular assays and using X-ray crystallography. Compared to the noncovalent G9a/GLP inhibitor UNC0642, covalent inhibitor 8 displayed improved potency in enzymatic and cellular assays. Interestingly, compound 8 also displayed potential kinetic preference for covalently modifying G9a over GLP. Collectively, compound 8 could be a useful chemical tool for studying the functional roles of G9a and GLP by covalently modifying and inhibiting these methyltransferases.