Abstract 5006: High-throughput TR-FRET cellular assays for interrogating histone H3 methylation

Abstract Post-translational modifications such as phosphorylation, acetylation and methylation play important roles in regulating the structures and functions of histones, which in turn regulate gene expression and DNA repair and replication. Histone modifying enzymes, such as deacetylases, methyltransferases and demethylases, have been pursued as therapeutic targets for various diseases. However, detection of the activities of these enzymes in high-throughput cell-based formats has remained challenging. We have developed high-throughput LanthaScreen® cellular assays for histone H3 site-specific modifications. These assays utilize cells expressing green fluorescence protein (GFP) tagged-histone H3 transiently delivered via BacMam and terbium labeled-anti-histone H3 modification-specific antibodies. Robust time-resolved Foerster resonance energy transfer signals were detected for H3 lysine-9 di-methylation (K9me2), lysine-4 di- (K4me2) and tri-methylation (K4me3) and lysine-27 tri-methylation (K27me3). Consistent with previous reports, hypoxic stress increased K4 methylation levels and methyltransferase G9a inhibitor UNC-0638 decreased K9me2 levels significantly with little effects on other modifications. Further validation of these assays using methyltransferases-specific RNAi oligos demonstrated that EZH2-specific RNAi reduced the level of K27me3 with little effect on the other three modifications, whereas G9a RNAi and SMYD3 RNAi reduced K9me2 and K4me2/3, respectively. The use of BacMam gene delivery system enables the measurement of these histone methylations in a variety of cell backgrounds including primary cells. In conclusion, we have developed homogenous cellular assays that can enable the high-throughput screening for modulators of histone H3 methylation at various lysine sites. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5006. doi:1538-7445.AM2012-5006