Reversible acetylation of the chromatin remodelling complex NoRC is required for non-coding RNA-dependent silencing.

The SNF2h (sucrose non-fermenting protein 2 homologue)-containing chromatin-remodelling complex NoRC silences a fraction of ribosomal RNA genes (rDNA) by establishing a heterochromatic structure at the rDNA promoter. Here we show that the acetyltransferase MOF (males absent on the first) acetylates TIP5, the largest subunit of NoRC, at a single lysine ...
residue, K633, adjacent to the TIP5 RNA-binding domain, and that the NAD(+)-dependent deacetylase SIRT1 (sirtuin-1) removes the acetyl group from K633. Acetylation regulates the interaction of NoRC with promoter-associated RNA (pRNA), which in turn affects heterochromatin formation, nucleosome positioning and rDNA silencing. Significantly, NoRC acetylation is responsive to the intracellular energy status and fluctuates during S phase. Activation of SIRT1 on glucose deprivation leads to deacetylation of K633, enhanced pRNA binding and an increase in heterochromatic histone marks. These results suggest a mechanism that links the epigenetic state of rDNA to cell metabolism and reveal another layer of epigenetic control that involves post-translational modification of a chromatin remodelling complex.
Mesh Terms:
Acetylation, Adenosine Triphosphatases, Animals, Blotting, Western, Cell Line, Cell Line, Tumor, Chromatin Assembly and Disassembly, Chromatin Immunoprecipitation, Chromosomal Proteins, Non-Histone, Flow Cytometry, Hela Cells, Heterochromatin, Histone Acetyltransferases, Humans, Lysine, Mice, NIH 3T3 Cells, RNA Interference, RNA, Ribosomal, S Phase, Sirtuin 1, Sirtuins
Nat. Cell Biol.
Date: Aug. 01, 2009
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