TREX2 Exonuclease Causes Spontaneous Mutations and Stress-Induced Replication Fork Defects in Cells Expressing RAD51

Autor: Jun Ho, Ko, Mi Young, Son, Qing, Zhou, Lucia, Molnarova, Lambert, Song, Jarmila, Mlcouskova, Atis, Jekabsons, Cristina, Montagna, Lumir, Krejci, Paul, Hasty
Rok vydání: 2019
Předmět:
Zdroj: Cell reports
ISSN: 2211-1247
Popis: SUMMARY DNA damage tolerance (DDT) and homologous recombination (HR) stabilize replication forks (RFs). RAD18/UBC13/three prime repair exonuclease 2 (TREX2)-mediated proliferating cell nuclear antigen (PCNA) ubiquitination is central to DDT, an error-prone lesion bypass pathway. RAD51 is the recombinase for HR. The RAD51 K133A mutation increased spontaneous mutations and stress-induced RF stalls and nascent strand degradation. Here, we report in RAD51K133A cells that this phenotype is reduced by expressing a TREX2 H188A mutation that deletes its exonuclease activity. In RAD51K133A cells, knocking out RAD18 or overexpressing PCNA reduces spontaneous mutations, while expressing ubiquitination-incompetent PCNAK164R increases mutations, indicating DDT as causal. Deleting TREX2 in cells deficient for the RF maintenance proteins poly(ADP-ribose) polymerase 1 (PARP1) or FANCB increased nascent strand degradation that was rescued by TREX2H188A, implying that TREX2 prohibits degradation independent of catalytic activity. A possible explanation for this occurrence is that TREX2H188A associates with UBC13 and ubiquitinates PCNA, suggesting a dual role for TREX2 in RF maintenance.
Graphical Abstract
In Brief Ko et al. find that TREX2’s exonuclease activity causes mutations, RF stalls, and strand degradation in cells expressing RAD51K133A. RAD18 deletion and PCNA overexpression reduce mutations, implicating DNA damage tolerance. Deleting TREX2 in PARP1-deficient or FANCB mutant cells increases strand degradation that is rescued by TREX2H188A, showing that TREX2’s catalytic activity is unimportant.
Databáze: OpenAIRE
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