Context-specific applications of CARM1 inhibitors: functional profiles of EZM2302 and TP-064.

backgroundCoactivator-associated arginine methyltransferase 1 (CARM1) regulates diverse cellular processes-including transcription, cell cycle progression, metabolism, and autophagy-through asymmetric dimethylation of both histone and non-histone substrates. Although TP-064 and EZM2302 both inhibit CARM1, they may elicit distinct biological effects.

methodsWe employed immunoblotting, subcellular fractionation, histone extraction, chromatin immunoprecipitation assay, quantitative PCR, and confocal microscopy to compare the effects of TP-064 and EZM2302. Substrate methylation and autophagic responses were evaluated under nutrient-deprived conditions.

resultsBoth TP-064 and EZM2302 inhibited CARM1-dependent methylation of non-histone substrates, including p300, GAPDH, and DRP1. However, TP-064 markedly reduced nuclear histone methylation marks H3R17me2a and H3R26me2a, whereas EZM2302 had minimal effect on these epigenetic modifications. Reflecting this differential impact, TP-064-but not EZM2302-suppressed transcription of autophagy-related genes and impaired LC3 lipidation and puncta formation under glucose deprivation. Consequently, TP-064 sensitized cells to energy stress by disrupting autophagic flux. These findings indicate that TP-064 inhibits both nuclear and cytoplasmic functions of CARM1, while EZM2302 selectively targets non-histone methylation events.

conclusionOur study reveals fundamental mechanistic differences between TP-064 and EZM2302 in regulating CARM1 substrates and downstream pathways. This substrate-selective inhibition has important implications for experimental design and therapeutic development, underscoring the need for context-specific selection of CARM1 inhibitors in both basic research and precision medicine.