1. Erasure of histone acetylation by Arabidopsis HDA6 mediates large-scale gene silencing in nucleolar dominance
- Author
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Olga Pontes, Craig S. Pikaard, Angel J. Enciso, Richard J. Lawrence, Wanda Viegas, Michael K. Gross, Keith Earley, Rachel Reuther, Manuela Silva, and Nuno Neves
- Subjects
0106 biological sciences ,DNA, Plant ,Arabidopsis ,SAP30 ,Biology ,01 natural sciences ,Histone Deacetylases ,Substrate Specificity ,Histones ,Histone H4 ,Cytosine ,03 medical and health sciences ,Histone H3 ,gene silencing ,nucleolar dominance ,Histone H1 ,Histone H2A ,Genetics ,Histone code ,Gene Silencing ,Promoter Regions, Genetic ,030304 developmental biology ,0303 health sciences ,Arabidopsis Proteins ,Lysine ,Acetylation ,Genes, rRNA ,DNA Methylation ,Histone methyltransferase ,chromatin ,RNA Interference ,Histone deacetylase ,Cell Nucleolus ,epigenetic ,Research Paper ,010606 plant biology & botany ,Developmental Biology - Abstract
Nucleolar dominance describes the silencing of one parental set of ribosomal RNA (rRNA) genes in a genetic hybrid, an epigenetic phenomenon that occurs on a scale second only to X-chromosome inactivation in mammals. An RNA interference (RNAi) knockdown screen revealed that the predicted Arabidopsis histone deacetylase, HDA6, is required for rRNA gene silencing in nucleolar dominance. In vivo, derepression of silenced rRNA genes upon knockdown of HDA6 is accompanied by nucleolus organizer region (NOR) decondensation, loss of promoter cytosine methylation, and replacement of histone H3 Lys 9 (H3K9) dimethylation with H3K4 trimethylation, H3K9 acetylation, H3K14 acetylation, and histone H4 tetra-acetylation. Consistent with these in vivo results, purified HDA6 deacetylates lysines modified by histone acetyltransferases whose substrates include H3K14, H4K5, and H4K12. HDA6 localizes, in part, to the nucleolus, supporting a model whereby HDA6 erases histone acetylation as a key step in an epigenetic switch mechanism that silences rRNA genes through concerted histone and DNA modifications.
- Published
- 2006