Loss of the Ash2l subunit of histone H3K4 methyltransferase complexes promotes chromatin compaction at promoters [ChIP-seq CTCF]
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ABSTRACT: Cell fate decisions are closely associated with changes in gene expression programs. A large number of post-translational modifications of core histones contribute to controlling the expression of genes. A modification that is closely correlated with open chromatin and gene transcription is methylation of lysine 4 of histone H3 (H3K4). It is catalyzed by methyltransferases of the KMT2 family, which require interaction with 4 core subunits, WDR5, RBBP5, ASH2L and DPY30, for catalytic activity. Ash2l is required for organismal development and for tissue homeostasis in the mouse. In mouse embryo fibroblasts (MEFs), the loss of Ash2l results in downregulated gene expression, which provokes a senescence phenotype. We now find that both H3K4 mono- and tri-methylation (H3K4me1 and me3, respectively) are deregulated. H3K4me3 is lost while H3K4me1 is increased at promoters upon knockout of Ash2l. In particular, loss of H3K4me3 at promoters correlates with downregulation of gene expression, which is particularly obvious at CpG island promoters. Ash2l loss results in an increase of histone H3 loading at promoters, paralleled by enhanced chromatin compaction. This is accompanied by an increase of repressing and a decrease of activating histone marks. One of the sequence-specific transcription factors with altered binding upon depletion of Ash2l is CTCF. It is lost from some promoter-associated sites, but gained binding in other regions of the genome. This suggests that in addition to the well-known effects on H3K4 methylation upon depleting KMT2 complex components, Ash2l loss affects chromatin compaction. Whether the decrease of H3K4me3 promotes chromatin compaction at promoters or whether these are independent consequences of Ash2l loss remains to be determined. We suggest that both contribute mechanistically to gene repression and thus to the observed cellular effects.
ORGANISM(S): Mus musculus
PROVIDER: GSE205231 | GEO | 2022/12/13
REPOSITORIES: GEO
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