XPA-Mediated Regulation of Global Nucleotide Excision Repair by ATR Is p53-Dependent and Occurs Primarily in S-Phase

Abstract

Cell cycle checkpoints play an important role in regulation of DNA repair pathways. However, how the regulation occurs throughout the cell cycle remains largely unknown. Here we demonstrate that nucleotide excision repair (NER) is regulated by the ATR/p53 checkpoint via modulation of XPA nuclear import and that this regulation occurs in a cell cycle-dependent manner. We show that depletion of p53 abrogated the UV-induced nuclear translocation of XPA, while silencing of Chk1 or MAPKAP Kinase-2 (MK2) had no effect. Inhibition of p53 transcriptional activities and silencing of p53-Ser15 phosphorylation also reduced the damage-induced XPA nuclear import. Furthermore, in G1-phase cells the majority of XPA remained in the cytoplasm even after UV treatment. By contrast, while most of the XPA in S-phase cells was initially located in the cytoplasm before DNA damage, UV irradiation stimulated bulk import of XPA into the nucleus. Interestingly, the majority of XPA molecules always were located in the nucleus in G2-phase cells no matter whether the DNA was damaged or not. Consistently, the UV-induced Ser15 phosphorylation of p53 occurred mainly in S-phase cells, and removal of cyclobutane pyrimidine dimers (CPDs) was much more efficient in S-phase cells than in G1-phase cells. Our results suggest that upon DNA damage in S phase, NER could be regulated by the ATR/p53-dependent checkpoint via modulation of the XPA nuclear import process. In contrast, the nuclear import of XPA in G1 or G2 phase appears to be largely independent of DNA damage and p53.

Noise exposure potentiates the subcellular distribution of nucleotide excision repair proteins within spiral ganglion neurons

“…This nuclear reactivity is a dense accumulation of reaction products that is enclosed by a prominent cytoplasm with residual immunoreactivity. This distinct distribution pattern is consistent with the translocation of NER proteins to the nucleus to bind damaged DNA (Wu et al, 2007;Li et al, 2011).…”

“…Furthermore, XPA induces specificity to the repair process, positions nucleases around the lesion and XPA stays bound to the repair site until the lesion is removed from the genome (Feng et al, 1997;Lambert and Yang, 2000; Bartels and Lambert, 2007). The presence of XPA in the nucleus is considered a signature characteristic for ongoing NER activity and depletion of XPA from the nucleus indicates cessation of NER (Wu et al, 2007;Li, et al, 2011).…”

Targeting DNA repair with aphidicolin sensitizes primary chronic lymphocytic leukemia cells to purine analogs

“…Among the DNA repair pathways involving polymerases δ/ε, namely long-patch BER, MMR and NER, only the latter is thought to operate in non-dividing cells [23]. That NER could be the pathway inhibited by aphidicolin in CLL cells in response to purine analogs is supported by several observations: (1) the repair of UV-C-induced DNA damage, known to occur by NER, was inhibited by aphidicolin, (2) XPA, an essential factor for NER, was translocated from the cytosol to the nucleus after fludarabine, as previously observed after UV and alkylating agent treatment [28, 29, 38], and (3) silencing of XPA in cell lines, including a CLL cell line, resulted in higher caspase-3 activation in response to fludarabine. Moreover, using genome-wide expression profiling, we previously observed that four NER-associated genes ( PCNA , XPC, GADD45 , and DDB2) were among the most up-regulated genes in CLL cells after treatment with fludarabine or cladribine in vitro [39].…”

Alteration of DNA damage signaling pathway profile in radiation-treated glioblastoma stem-like cells

“…The XPA protein is one of eight factors that were found to be deficient in XP disorders, which are characterized by an increased sensitivity to UV radiation and a predisposition to development of skin cancers (16). Functionally, XPA is considered to play roles in verifying DNA damage, stabilizing repair intermediates, and recruiting other NER factors to the damaged DNA (17).…”