Dataset Information

SIRT7-dependent deacetylation of fibrillarin controls H2A methylation and rRNA synthesis during the cell cycle

ABSTRACT: Fibrillarin (FBL) is a dual function nucleolar protein which catalyses 2´-O methylation of pre-rRNA and methylation of histone H2A at glutamine 104 (H2AQ104me). The mechanisms that regulate FBL activity are unexplored. Here we show that FBL is acetylated at several lysine residues by the acetyltransferase CBP and deacetylated by SIRT7. While reversible acetylation does not impact FBL-mediated pre-rRNA methylation, hyperacetylation impairs the interaction of FBL with histone H2A and chromatin, thereby compromsing H2AQ104 methylation (H2AQ104me) and rDNA transcription. SIRT7-dependent deacetylation of FBL ensures H2AQ104me and high levels of rRNA synthesis during interphase. At the onset of mitosis, nucleolar disassembly is accompanied by hyperacetylation of FBL, loss of H2AQ104me and repression of Pol I transcription. H2AQ104me and transcriptional activity are restored by overexpression of an acetylation-deficient but not by an acetylation-mimicking FBL mutant. The results reveal that SIRT7-dependent deacetylation impacts nucleolar activity by a FBL-driven circuitry that mediates cell cycle-dependent fluctuation of rDNA transcription.

ORGANISM(S): Homo sapiens

PROVIDER: GSE115360 | GEO | 2018/12/12

REPOSITORIES: GEO

ACCESS DATA

Similar Datasets

Project description:Transcription of the several hundred of mouse and human Ribosomal RNA (rRNA) genes accounts for the majority of RNA synthesis in the cell nucleus and is the determinant of cytoplasmic ribosome abundance, a key factor in regulating gene expression. The rRNA genes, referred to globally as the rDNA, are clustered as direct repeats at the Nucleolar Organiser Regions, NORs, of several chromosomes, and in many cells the active repeats are transcribed at near saturation levels. The rDNA is also a hotspot of recombination and chromosome breakage, and hence understanding its control has broad importance. Despite the need for a high level of rDNA transcription, typically only a fraction of the rDNA is transcriptionally active, and some NORs are permanently silenced by CpG methylation. Various chromatin-remodelling complexes have been implicated in counteracting silencing to maintain rDNA activity. However, the chromatin structure of the active rDNA fraction is still far from clear. Here we have combined a high-resolution ChIP-Seq protocol with conditional inactivation of key basal factors to better understand what determines active rDNA chromatin. The data resolve questions concerning the interdependence of the basal transcription factors, show that preinitiation complex formation is driven by the architectural factor UBF (UBTF) independently of transcription, and exclude a significant role for termination by a torpedomechanism. They further reveal the existence of an asymmetric Boundary Complex formed by CTCF, Cohesin and three phased nucleosomes lying adjacent to the rDNA Enhancer and an arrested RNA Polymerase I complex. We find that this complex is the only site of active histone modification in the whole 45kbp rDNA repeat. Strikingly, the Enhancer Boundary Complex not only delimits each functional rRNA gene, but also is stably maintained after gene inactivation and the re-establishment of surrounding repressive chromatin. Our data define the poised state of rDNA chromatin and place the Enhancer Boundary Complex as the likely entry point for the chromatin remodelling complexes.

Dataset Information

SIRT7-dependent deacetylation of fibrillarin controls H2A methylation and rRNA synthesis during the cell cycle

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure