Poster: "In vivo selection of JARID histone demethylases inhibitors and their use to enlighten the biological role of these enzymes in yeast and mammalian cells with focus on transcriptional regulation”

We recently discovered in S.cerevisiae an interesting conditional negative genetic interaction between the unique JARID histone demethylase Jhd2, responsible for H3K4 demethylation, and Not4, a protein which is involved in several different regulatory processes, including transcriptional regulation, RNA stability and Jhd2 degradation. The double deletion mutant Δjhd2/Δnot4 is hypersensitive to rapamycin and its sensitivity is promptly suppressed by episomal Jhd2 expression in the double deletion strain. While this genetic interaction could be useful for the understanding of the transcriptional role of Jhd2 in yeast, which is still elusive, it is also an ideal system for in vivo screening of inhibitors specific for JARID demethylases. In a pilot screening on 45 candidate small molecules, we identified a compound which specifically inhibits Jhd2 in vivo, leading to a consistent increase in trimethyl-H3K4. The compound inhibits human JARID 1B and 1D in vitro and shows a strong cytostatic effect, a mild cytotoxicity and a selective increase of trimethyl-H3K4 in HeLa cells. We better characterized the inhibitor’s effects in yeast and mammalian cells, with focus on transcriptional effects. The results in yeast enlighten a role of Jhd2 in regulating a set of genes transcriptionally induced upon diauxic shift.