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bioRxiv · 10.1101/2020.06.04.133272

DNMT3b Dysfunction Promotes DNA cleavages at Centromeric R-loops to Increase Centromere Instability

Shih, H.-T.·Chen, W.-Y.·Wang, H.-Y.·Huang, H.-D.·Chou, C.-H.·Chang, Z.-F.
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Abstract

This study investigates how DNA methyltransferase 3b (DNMT3b) dysfunction causes genome instability. We showed that in DNMT3b deficient cells, R-loops contribute to prominent {gamma}H2AX signal, which was mapped to repetitive satellite sequences including centromere regions. By ChIP and DRIP analyses, our data revealed that centromeric R-loops in DNMT3b deficient cells are removed by XPG/XPF, thus generating DNA breaks in centromeres to increase mitotic aberration. In immunodeficiency-centromeric instability-facial anomalies (ICF) patient cells carrying the loss-of-function mutation at DNMT3b, knockdown of XPG/XPF in ICF cells also reduces DNA breaks in centromere while bringing up centromeric R-loop to the level similar to that in wild-type cells. These results suggest that DNMT3b has a critical function in preventing XPG/XPF-mediated cleavages at centromeric R-loop sites. Finally, we showed the involvement of non-homologous end-joining repair at centromeric sites in ICF cells. Thus, DNA cleavages at centromeric R-loops with error-prone repair undermine centromere stability in ICF cells.

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Shih, H.-T., Chen, W.-Y., Wang, H.-Y., Huang, H.-D., Chou, C.-H., Chang, Z.-F.. 2020-06-04. DNMT3b Dysfunction Promotes DNA cleavages at Centromeric R-loops to Increase Centromere Instability. https://doi.org/10.1101/2020.06.04.133272

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