title: Nuclear organization changes and the epigenetic silencing of FLC during vernalization.
abstract: Changes in nuclear organization are considered an important complement to trans-acting factors, histone modifications and non-coding RNAs in robust and stable epigenetic silencing. However, how these multiple layers interconnect mechanistically to reinforce each other's activity is still unclear. A system providing long timescales facilitating analysis of these interconnections is vernalization. This involves the Polycomb-mediated epigenetic silencing of flowering locus C (FLC) that occurs as Arabidopsis plants are exposed to prolonged cold. Analysis of changes in nuclear organization during vernalization has revealed that disruption of a gene loop and physical clustering of FLC loci are part of the vernalization mechanism. These events occur at different times and thus contribute to distinct aspects of the silencing mechanism. The physical clustering of FLC loci is tightly correlated with the accumulation of specific Polycomb complexes/H3K27me3 at a localized intragenic site during the cold. Since the quantitative nature of vernalization is a reflection of a bistable cell autonomous switch in an increasing number of cells, this correlation suggests a tight connection between the switching mechanism and changes in nuclear organization. This integrated picture is likely to be informative for many epigenetic mechanisms.
authors.affiliation: Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Danling
authors.initials: D
authors.lastname: Zhu
authors.affiliation: Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Rosa
authors.affiliation: Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK. Electronic address: caroline.dean@jic.ac.uk.
authors.forename: Caroline
authors.initials: C
authors.lastname: Dean
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002467:Cell Nucleus / Q000502:physiology*; D044127:Epigenesis, Genetic; D035264:Flowers / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D026161:MADS Domain Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C418902:At5g10140 protein, Arabidopsis; D026161:MADS Domain Proteins
keywords: FLC; epigenetic silencing; gene loop; vernalization