Genome binding/occupancy profiling by high throughput sequencing Methylation profiling by high throughput sequencing
Summary
Precise deposition of CpG methylation is critical for mammalian development and tissue homeostasis and is often dysregulated in human diseases. The localization of de novo DNA methyltransferases 3A (DNMT3A) and 3B (DNMT3B) is facilitated by PWWP domain recognition of histone H3 lysine 36 (H3K36) methylation (Baubec et al. 2015, Weinberg et al. 2019) and is normally excluded from CpG islands (CGIs) (Wu et al. 2010). However, CpG methylation of CGIs that are regulated by Polycomb repressive complexes (PRCs) has been observed during embryogenesis (Chen et al. 2019), cellular differentiation (Mohn et al. 2008), and cancer progression (Ohm et al. 2007, Schlesinger et al. 2007, Widschwendter et al. 2007), suggesting that an uncharacterized mechanism exists to compete for de novo DNMT recruitment. Here we report that DNMT3A PWWP domain mutations recently identified in paragangliomas (Remacha et al. 2018) and microcephalic dwarfism (Heyn et al. 2019) promote localization of DNMT3A to CGIs in a PRC1-dependent manner. Genome-wide analysis shows that DNMT3A PWWP mutants redistribute to regions containing ubiquitylation of histone H2A at lysine 119 (H2AK119Ub) deposited by PRC1, irrespective of the levels of PRC2-catalyzed tri-methylation of histone H3 at lysine 27 (H3K27me3). DNMT3A, but not DNMT3B, is capable of directly interacting with H2AK119Ub-modified nucleosomes through a putative amino-terminal ubiquitin-dependent recruitment (UDR) region, which serves as an alternative form of genomic targeting in cells upon loss of PWWP reader function. Ablation of PRC1 abrogates localization of DNMT3A PWWP mutants to CGIs and prevents aberrant hypermethylation at these sites. Our study implies that a balance between DNMT3A recruitment by distinct reader domains guides de novo CpG methylation and may underlie the abnormal DNA methylation landscapes observed in human cancers and developmental disorders.
Overall design
ChIP-seq for DNMT3A1 variants and histone H3 post-translational modifications, and RRBS in parental C3H10T1/2 cells. ChIP-seq for DNMT3A1 variants, ChIP-Rx (Drosophila spike-in) for H2AK119Ub, and H3K27me3, and RRBS in sgRing1a/b C3H10T1/2 cells.
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