9 research outputs found
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ZNF432 stimulates PARylation and inhibits DNA resection to balance PARPi sensitivity and resistance
Zinc finger (ZNF) motifs are some of the most frequently occurring domains in the human genome. It was only recently that ZNF proteins emerged as key regulators of genome integrity in mammalian cells. In this study, we report a new role for the KrĂĽppel-type ZNF-containing protein ZNF432 as a novel poly(ADP-ribose) (PAR) reader that regulates the DNA damage response. We show that ZNF432 is recruited to DNA lesions via DNA- and PAR-dependent mechanisms. Remarkably, ZNF432 stimulates PARP-1 activity in vitro and in cellulo. Knockdown of ZNF432 inhibits phospho-DNA-PKcs and increases RAD51 foci formation following irradiation. Moreover, purified ZNF432 preferentially binds single-stranded DNA and impairs EXO1-mediated DNA resection. Consequently, the loss of ZNF432 in a cellular system leads to resistance to PARP inhibitors while its overexpression results in sensitivity. Taken together, our results support the emerging concept that ZNF-containing proteins can modulate PARylation, which can be embodied by the pivotal role of ZNF432 to finely balance the outcome of PARPi response by regulating homologous recombination.</p
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A CRISPR-Cas9 screen identifies EXO1 as a formaldehyde resistance gene
Fanconi Anemia (FA) is a rare, genome instability-associated disease characterized by a deficiency in repairing DNA crosslinks, which are known to perturb several cellular processes, including DNA transcription, replication, and repair. Formaldehyde, a by-product of metabolism, is thought to drive FA by generating DNA interstrand crosslinks (ICLs) and DNA-protein crosslinks (DPCs). However, the impact of formaldehyde on global cellular pathways has not been investigated thoroughly. Herein, using a pangenomic CRISPR-Cas9 screen, we identify EXO1 as a critical regulator of formaldehyde-induced DNA lesions. We show that EXO1 knockout cell lines exhibit formaldehyde sensitivity leading to the accumulation of replicative stress, DNA double-strand breaks, and quadriradial chromosomes, a typical feature of FA. After formaldehyde exposure, EXO1 is recruited to chromatin, protects DNA replication forks from degradation, and functions in parallel with the FA pathway to promote cell survival. In vitro, EXO1-mediated exonuclease activity is proficient in removing DPCs. Collectively, we show that EXO1 limits replication stress and DNA damage to counteract formaldehyde-induced genome instability.</p
Distribution of p.Thr141Ile, p.Ser7Ser and p.Ser11Ser by race/ethnicity.
<p>Distribution of p.Thr141Ile, p.Ser7Ser and p.Ser11Ser by race/ethnicity.</p
Distribution of <i>ABRAXAS</i> rare variants (<i>i</i>.<i>e</i>. with a minor allele frequency<1% in the Exome Variant Server (EVS)) identified in the BCFR.
<p>Distribution of <i>ABRAXAS</i> rare variants (<i>i</i>.<i>e</i>. with a minor allele frequency<1% in the Exome Variant Server (EVS)) identified in the BCFR.</p
Analysis of potentially pathogenic <i>ABRAXAS</i> in-frame deletion or rare missense substitutions.
<p>Analysis of potentially pathogenic <i>ABRAXAS</i> in-frame deletion or rare missense substitutions.</p
p.Gly39val and p.Thr141Ile ABRAXAS mutants have defects in gamma-H2AX formation.
<p>(A) Typical DNA damage foci of ABRAXAS in shABRAXAS (shABX145) MCF7 cells complemented with ABRAXAS-HA-Flag, ABRAXAS-HA-Flag pThr141Ile, or ABRAXAS-HA-Flag pGly39Val. The anti-Flag antibody was used to monitor ABRAXAS foci formation (green), anti-gamma-H2AX (red) and the merge picture is depicted. In blue, DAPI staining. (B) Quantification of gamma-H2AX foci formation in MCF7 cells after neocarzinostatin treatment and release. P-values were obtained with a Wilcoxon’s Test with N = 100 cells from four independent experiments.</p
Stratified analyses of the common SNP rs13125836 (c. 1117G>A, p.Asp373Asn) on breast cancer risk in the BCFR.
<p>Stratified analyses of the common SNP rs13125836 (c. 1117G>A, p.Asp373Asn) on breast cancer risk in the BCFR.</p
ABRAXAS multiple-sequence alignment.
<p>Substitution designations are indicated above the corresponding human reference sequence residue. Amino acid symbols are colored to represent standard Dayhoff groupings.</p
Distribution of cases and controls by study center and by ethnicity in the BCFR.
<p>Distribution of cases and controls by study center and by ethnicity in the BCFR.</p