RESUMO
Spreading of H3K27me3 is crucial for the maintenance of mitotically inheritable Polycomb-mediated chromatin silencing in animals and plants. However, how Polycomb repressive complex 2 (PRC2) accesses unmodified nucleosomes in spreading regions for spreading H3K27me3 remains unclear. Here, we show in Arabidopsis thaliana that the chromatin remodeler PICKLE (PKL) plays a specialized role in H3K27me3 spreading to safeguard cell identity during differentiation. PKL specifically localizes to H3K27me3 spreading regions but not to nucleation sites and physically associates with PRC2. Loss of PKL disrupts the occupancy of the PRC2 catalytic subunit CLF in spreading regions and leads to aberrant dedifferentiation. Nucleosome density increase endowed by the ATPase function of PKL ensures that unmodified nucleosomes are accessible to PRC2 catalytic activity for H3K27me3 spreading. Our findings demonstrate that PKL-dependent nucleosome compaction is critical for PRC2-mediated H3K27me3 read-and-write function in H3K27me3 spreading, thus revealing a mechanism by which repressive chromatin domains are established and propagated.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Diferenciação Celular , Montagem e Desmontagem da Cromatina , Histonas , Nucleossomos , Complexo Repressor Polycomb 2 , Nucleossomos/metabolismo , Nucleossomos/genética , Arabidopsis/genética , Arabidopsis/metabolismo , Histonas/metabolismo , Histonas/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Complexo Repressor Polycomb 2/metabolismo , Complexo Repressor Polycomb 2/genética , Regulação da Expressão Gênica de Plantas , Cromatina/metabolismo , Cromatina/genéticaRESUMO
MULTICOPY SUPPRESSOR OF IRA1 (MSI1) is a conserved subunit of Polycomb Repressive Complex 2 (PRC2), which mediates gene silencing by histone H3 lysine 27 trimethylation (H3K27Me3). Here, we demonstrated that MSI1 interacts with the RPD3-like histone deacetylase HDA6 both in vitro and in vivo. MSI1 and HDA6 are involved in flowering and repress the expression of FLC, MAF4, and MAF5 by removing H3K9 acetylation but adding H3K27Me3. Chromatin immunoprecipitation analysis showed that HDA6 and MSI1 interdependently bind to the chromatin of FLC, MAF4, and MAF5. Furthermore, H3K9 deacetylation mediated by HDA6 is dependent on MSI1, while H3K27Me3 mediated by PRC2 containing MSI1 is also dependent on HDA6. Taken together, these data indicate that MSI1 and HDA6 act interdependently to repress the expression of FLC, MAF4, and MAF5 through histone modifications. Our findings reveal that the HDA6-MSI1 module mediates the interaction between histone H3 deacetylation and H3K27Me3 to repress gene expression involved in flowering time control.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Cromatina/metabolismo , Flores/metabolismo , Histona Desacetilases/metabolismo , Acetilação , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Imunoprecipitação da Cromatina , Flores/genética , Regulação da Expressão Gênica de Plantas , Inativação Gênica , Histona Desacetilases/genética , Histonas/metabolismo , Proteínas de Domínio MADS/metabolismo , Complexo Repressor Polycomb 2/genética , Complexo Repressor Polycomb 2/metabolismo , Proteínas Repressoras/metabolismoRESUMO
Histone deacetylases (HDAs) play an important role in transcriptional regulation of multiple biological processes. In this study, we investigated the function of HDA15 in abscisic acid (ABA) responses. We used immunopurification coupled with mass spectrometry-based proteomics to identify proteins interacting with HDA15 in Arabidopsis (Arabidopsis thaliana). HDA15 interacted with the core subunits of the MOS4-associated complex (MAC), MAC3A and MAC3B, with interaction between HDA15 and MAC3B enhanced by ABA. hda15 and mac3a/mac3b mutants were ABA-insensitive during seed germination and hyposensitive to salinity. RNA sequencing analysis demonstrated that HDA15 and MAC3A/MAC3B co-regulate ABA-responsive intron retention (IR). Furthermore, HDA15 reduced the histone acetylation level of genomic regions near ABA-responsive IR sites and the association of MAC3B with ABA-responsive pre-mRNA was dependent on HDA15. Our results indicate that HDA15 is involved in ABA responses by interacting with MAC3A/MAC3B to mediate splicing of introns.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Fenômenos Biológicos , Ácido Abscísico/metabolismo , Ácido Abscísico/farmacologia , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Germinação/genética , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Íntrons/genética , Sementes/metabolismoRESUMO
BRAHMA (BRM) is the ATPase of the SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodelling complex, which is indispensable for transcriptional inhibition and activation, associated with vegetative and reproductive development in Arabidopsis thaliana. Here, we show that BRM directly binds to the chromatin of SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1), which integrates multiple flowering signals to regulate floral transition, leading to flowering. In addition, genetic and molecular analysis showed that BRM interacts with GNC (GATA, NITRATE-INDUCIBLE, CARBON METABOLISM INVOLVED), a GATA transcription factor that represses flowering by directly repressing SOC1 expression. Furthermore, BRM is recruited by GNC to directly bind to the chromatin of SOC1. The transcript level of SOC1 is elevated in brm-3, gnc, and brm-3/gnc mutants, which is associated with increased histone H3 lysine 4 tri-methylation (H3K4Me3) but decreased DNA methylation. Taken together, our results indicate that BRM associates with GNC to regulate SOC1 expression and flowering time.