title: Arabidopsis transcriptional repressor VAL1 triggers Polycomb silencing at FLC during vernalization.
abstract: The determinants that specify the genomic targets of Polycomb silencing complexes are still unclear. Polycomb silencing of Arabidopsis FLOWERING LOCUS C (FLC) accelerates flowering and involves a cold-dependent epigenetic switch. Here we identify a single point mutation at an intragenic nucleation site within FLC that prevents this epigenetic switch from taking place. The mutation blocks nucleation of plant homeodomain-Polycomb repressive complex 2 (PHD-PRC2) and indicates a role for the transcriptional repressor VAL1 in the silencing mechanism. VAL1 localizes to the nucleation region in vivo, promoting histone deacetylation and FLC transcriptional silencing, and interacts with components of the conserved apoptosis- and splicing-associated protein (ASAP) complex. Sequence-specific targeting of transcriptional repressors thus recruits the machinery for PHD-PRC2 nucleation and epigenetic silencing.
authors.affiliation: Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Julia I
authors.initials: JI
authors.lastname: Qüesta
authors.affiliation: Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK. Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
authors.forename: Jie
authors.initials: J
authors.lastname: Song
authors.affiliation: Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Nuno
authors.initials: N
authors.lastname: Geraldo
authors.affiliation: Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Hailong
authors.initials: H
authors.lastname: An
authors.affiliation: Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Caroline
authors.initials: C
authors.lastname: Dean
mesh_terms: D000107:Acetylation; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000502:physiology*; D001483:Base Sequence; D035264:Flowers / Q000235:genetics / Q000254:growth & development*; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D056426:Genetic Loci; D006657:Histones / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics*; D026161:MADS Domain Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D063151:Polycomb Repressive Complex 2 / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; C418902:At5g10140 protein, Arabidopsis; C504531:HSI2 protein, Arabidopsis; D006657:Histones; D018398:Homeodomain Proteins; D026161:MADS Domain Proteins; D012097:Repressor Proteins; D063151:Polycomb Repressive Complex 2