Negative epigenetic regulation of rRNA expression

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R-HSA-5250941
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Pathway
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Homo sapiens
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Transcription of rRNA genes is controlled by epigenetic activation and repression (reviewed in McStay and Grummt 2008, Goodfellow and Zomerdijk 2012, Grummt and Langst 2013). About half of the roughly 400 rRNA genes are expressed and these have the modifications of active chromatin: unmethylated DNA and acetylated histones. Repressed genes generally have methylated DNA and histone H3 methylated at lysine-9. Regulators of repression include the eNoSC complex, SIRT1, and the NoRC complex.
SIRT1 negatively regulates rRNA expression as a subunit of the eNoSC complex, which deacetylates histone H3 and dimethylates lysine-9 of histone H3 (H3K9me2).
NoRC negatively regulates rRNA expression by shifting a nucleosome near the start of rRNA transcription into a more repressive location and recruiting Histone Deacetylase 1 and 2 (HDAC1, HDAC2) and DNA Methyltransferase 1 and 3b (DNMT1, DNMT3b).

Literature References
PubMed ID Title Journal Year
18616426 The epigenetics of rRNA genes: from molecular to chromosome biology

McStay, B, Grummt, I

Annu Rev Cell Dev Biol 2008
23150253 Basic mechanisms in RNA polymerase I transcription of the ribosomal RNA genes

Goodfellow, SJ, Zomerdijk, JC

Subcell. Biochem. 2012
23063748 Epigenetic control of RNA polymerase I transcription in mammalian cells

Grummt, I, Längst, G

Biochim. Biophys. Acta 2013
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