FIG 1 .

Inhibition of LSD1 by monoamine oxidase inhibitors (MAOIs). Upon infection, the HSV or VZV IE gene activator recruits the HCF-1 coactivator complex to viral IE gene promoters to limit the accumulation of repressive histone H3K9 methylation and promote the installation of activating marks such as histone H3K4 methylation. The HCF-1 coactivator complex consists of a set of histone modification components, including the histone H3K9 demethylase LSD1 and the H3K4 methyltransferase Set1 or MLL. MAOIs such as tranylcypromine (TCP) block LSD1 demethylation activity, resulting in stable or increased levels of repressive marks on viral IE gene promoters and suppression of IE gene transcription.