Abstract
Lysine demethylation of proteins such as histones is catalyzed by several classes of enzymes, including the FAD-dependent amine oxidases KDM1A/B. The KDM1 family is homologous to the mitochondrial monoamine oxidases MAO-A/B and produces hydrogen peroxide in the nucleus as a byproduct of demethylation. Here, we show KDM1A is highly thiol-reactive in vitro and in cellular models. Enzyme activity is potently and reversibly inhibited by the drug disulfiram and by hydrogen peroxide. Hydrogen peroxide produced by KDM1A catalysis reduces thiol labeling and inactivates demethylase activity over time. MALDI-TOF mass spectrometry indicates that hydrogen peroxide blocks labeling of cysteine 600, which we propose forms an intramolecular disulfide with cysteine 618 to negatively regulate the catalytic activity of KDM1A. This activity-dependent regulation is unique among histone-modifying enzymes but consistent with redox sensitivity of epigenetic regulators.
Highlights
Lysine demethylation of proteins such as histones is catalyzed by several classes of enzymes, including the flavin adenine dinucleotide (FAD)-dependent amine oxidases KDM1A/B
KDM1A Is Reversibly Inhibited by Thiol-reactive Compounds—Tranylcypromine (TCP; Parnate) inhibits FAD-dependent amine oxidases by forming covalent cofactor adducts [7]
Epigenetic machinery is regulated by the cellular redox state through several mechanisms, including fluctuations in the availability of metabolites utilized as substrates and cofactors, interaction with redox-sensitive transcription factors, modification by redox-sensitive enzymes, and direct modification by ROS/reactive nitrogen species (RNS) [24]
Summary
Lysine demethylation of proteins such as histones is catalyzed by several classes of enzymes, including the FAD-dependent amine oxidases KDM1A/B. The role of the KDM1 family in hypoxia is less well-established, but KDM1A has been shown to mediate hypoxia-induced histone lysine demethylation at the BRCA1 and RAD51 promoters in MCF-7 breast cancer cells and the MLH1 promoter in RKO colon cancer cells [9, 10] In addition to their requirement for molecular oxygen, all KDMs liberate the former N-methyl group as formaldehyde. Machinery to the 8-oxoG lesions caused by KDM1A catalytic activity has been linked to estrogen-, Myc-, and androgen-induced transcriptional activation [13,14,15] These examples suggest a critical role for H2O2 generation in the mechanism of KDM1A distinct from other classes of histone lysine demethylases. We propose a mechanism where KDM1A utilizes a thiol/disulfide switch to sense H2O2, a unique auto-oxidation mechanism among histone modifiers but consistent with general mechanisms of redox sensing by epigenetic enzymes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
