Abstract
BackgroundPolycomb repressive complex 2 (PRC2) is an epigenetic transcriptional repression system, whose catalytic subunit (ENHANCER OF ZESTE HOMOLOG 2, EZH2 in animals) is responsible for trimethylating histone H3 at lysine 27 (H3K27me3). In mammals, gain-of-function mutations as well as overexpression of EZH2 have been associated with several tumors, therefore making this subunit a suitable target for the development of selective inhibitors. Indeed, highly specific small-molecule inhibitors of EZH2 have been reported. In plants, mutations in some PRC2 components lead to embryonic lethality, but no trial with any inhibitor has ever been reported.ResultsWe show here that the 1,5-bis (3-bromo-4-methoxyphenyl)penta-1,4-dien-3-one compound (RDS 3434), previously reported as an EZH2 inhibitor in human leukemia cells, is active on the Arabidopsis catalytic subunit of PRC2, since treatment with the drug reduces the total amount of H3K27me3 in a dose-dependent fashion. Consistently, we show that the expression level of two PRC2 targets is significantly increased following treatment with the RDS 3434 compound. Finally, we show that impairment of H3K27 trimethylation in Arabidopsis seeds and seedlings affects both seed germination and root growth.ConclusionsOur results provide a useful tool for the plant community in investigating how PRC2 affects transcriptional control in plant development.
Highlights
Polycomb repressive complex 2 (PRC2) is an epigenetic transcriptional repression system, whose catalytic subunit (ENHANCER OF ZESTE HOMOLOG 2, EZH2 in animals) is responsible for trimethylating histone H3 at lysine 27 (H3K27me3)
Immunoblot analysis of total proteins of RDS 3434- or Dimethyl sulfoxide (DMSO)-treated 5 days-old seedlings was performed with specific antibodies against H3K27me3
Measurement of the amount of proteins marked by H3K27me3 showed that the RDS 3434 inhibitor was effective in a dosedependent manner: while with 30 μM RDS 3434 the slight decrease (16%) of H3K27me3 marked proteins compared to the control was not significant, at 60 and 120 μM they were reduced by, respectively, 45 and 62% (Fig. 2)
Summary
Polycomb repressive complex 2 (PRC2) is an epigenetic transcriptional repression system, whose catalytic subunit (ENHANCER OF ZESTE HOMOLOG 2, EZH2 in animals) is responsible for trimethylating histone H3 at lysine 27 (H3K27me). The activity of PRC2 is crucial during endosperm formation as it controls the imprinting of several genes, and mutations in the imprinting machinery lead to embryonic lethality [13]. This has severely hindered studies on the function of PRC2 during seed development. This allowed to generate viable homozygous fie mutants, derived from seeds where the endosperm was of uniparental (maternal) origin [14, 15]
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