PML isoform expression and DNA break location relative to PML nuclear bodies impacts the efficiency of homologous recombination.

PML isoform expression and DNA break location relative to PML nuclear bodies impacts the efficiency of homologous recombination. Biochem Cell Biol. 2019 Oct 31;: Authors: Attwood KM, Salsman J, Chung D, Mathavarajah S, Van Iderstine C, Dellaire G Abstract Promyelocytic leukemia nuclear bodies (PML NBs) are nuclear subdomains that respond to genotoxic stress by increasing in number via changes in chromatin structure. However, the role of the PML protein and PML NBs in specific mechanisms of DNA repair has not been fully characterized. Here, we have directly examined the role of PML in homologous recombination (HR) using I-SceI extrachromosomal and chromosome-based homology-directed repair (HDR) assays, and in HDR by CRISPR/Cas9-mediated gene editing. We determined that PML loss can inhibit HR in an extrachromosomal HDR assay but had less of an effect on CRISPR/Cas9-mediated chromosomal HDR. Overexpression of PML also inhibited both CRISPR HDR and I-SceI-induced HDR using a chromosomal reporter, and in an isoform specific-manner. However, the impact of PML overexpression on the chromosomal HDR reporter was dependent on the intra-nuclear chromosomal positioning of the reporter. Specifically, HDR at the TAP1 gene locus, which is associated with PML NBs, was reduced compared to a locus not associated with a PML NB; yet, HDR could be reduced at the non-PML NB-associated locus by PML overexpression. Thus, both loss and overexpression of PML...
Source: Biochemistry and Cell Biology - Category: Biochemistry Authors: Tags: Biochem Cell Biol Source Type: research