Multiplexed Imaging of Posttranslational Modifications of Endogenous Proteins in Live Cells

Posttranslational histone modifications are associated with the regulation of genome function. Some modifications are quite stable to maintain epigenome states of chromatin, and others can exhibit dynamic changes in response to internal and external stimuli. To track the local and global changes in histone modifications, multiplexed imaging in living cells is beneficial. Among live cell probes for detecting histone modifications, genetically encoded modification-specific intracellular antibodies, or mintbodies, are convenient and suitable tools for this purpose. We here describe the mintbody-based methods to monitor the changes in histone modification levels induced by histone methyltransferase and deacetylase inhibitors. By measuring the nuclear to cytoplasmic intensity ratios of mintbodies in living cells, changes in histone H4 lysine 20 methylation states and the increase in histone H3 acetylation were detected.