Ricerc@Sapienza

The Polycomb repressive complex2 (PRC2) represents a transcriptional epigenetic repression system, and is responsible of trimethylating histone H3 at lysine27 (H3K27me3) through its catalytic subunit EZH2. In mammals, gain-of-function mutations and overexpression of EZH2 has been associated with several tumors, therefore making this subunit an ideal target for the development of selective inhibitors. Indeed, highly specific small-molecule inhibitors of EZH2 have been reported. In particular, the highly selective inhibitor of EZH2, UNC1999, has been shown to be highly effective in vitro for both wild-type and mutant EZH2, and to suppress H3K27me3 level over many epigenetic targets.
In plants, mutations in some PRC2 components lead to embryonic lethality, but no trial with any inhibitor has ever been reported. Taking advantage of the homology of the catalytic subunit between animals and plants, we have assessed the efficacy of the UNC1999 inhibitor in plants. We proved the effectiveness of UNC1999 on seedlings of Arabidopsis thaliana, since treatment with this inhibitor reduces the total amount of H3K27me3, as well as the level of this epigenetic mark in two PRC2 target genes, ABSCISIC ACID INSENSITIVE 3 (ABI3) and DOF AFFECTING GERMINATION1 (DAG1). To further improve this strategy, we propose to test new molecules for their efficacy, namely two EZH2 selective inhibitors synthesized in the laboratory of Prof. R. Costi (Sapienza,University of Rome,Dept. of Chemistry and Technology of Drugs). The effectiveness and selectivity of these molecules have been already proved on human leukemia cells.
Therefore, the aim of this research proposal is to validate the efficacy and the selectivity of these molecules on Arabidopsis seeds and seedlings. In addition to the molecular analysis on the expression level of three PRC2 target genes, a phenotypic analysis will be performed, to study the effect of the reduced H3K27me3 level during seedling development.