Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0268140 (XPF)
 549 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

DNA-protein crosslinks (DPC) involving all major histones are the dominant form of DNA damage in formaldehyde-exposed cells. In order to understand the repair mechanisms for these lesions we conducted detailed analysis of the stability of formaldehyde-induced DPC in vitro and in human cells. DNA-histone linkages were found to be hydrolytically unstable, with t(1/2) = 18.3 h at 37 degrees C. When histones were allowed to remain bound to DNA after crosslink breakage, the half-life of DPC increased to 26.3 h. This suggests that approximately 30% of spontaneously broken DPC could be re-established under physiological conditions. The half-lives of DPC in three human cell lines (HF/SV fibroblasts, kidney Ad293 and lung A549 cells) were similar and averaged 12.5 h (range 11.6-13.0 h). After adjustment for spontaneous loss, an active repair process was calculated to eliminate DPC from these cells with an average t(1/2) = 23.3 h. Removal of DPC from peripheral human lymphocytes was slower (t(1/2) = 18.1 h), due to inefficient active repair (t(1/2) = 66.6 h). This indicates that the major portion of DPC is lost from lymphocytes through spontaneous hydrolysis rather than being actively repaired. Depletion of intracellular glutathione from A549 cells had no significant effect on the initial levels of DPC, the rate of their repair or cell survival. Nucleotide excision repair does not appear to be involved in the removal of DPC, since the kinetics of DPC elimination in XP-A and XP-F fibroblasts were very similar to normal cells. Incubation of normal or XP-A cells with lactacystin, a specific inhibitor of proteosomes, caused inhibition of DPC repair, suggesting that the active removal of DPC in cells may involve proteolytic degradation of crosslinked proteins. XP-F cells showed somewhat higher sensitivity to formaldehyde, possibly signaling participation of XPF protein in the removal of residual peptide-DNA adducts.
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PMID:Loss of DNA-protein crosslinks from formaldehyde-exposed cells occurs through spontaneous hydrolysis and an active repair process linked to proteosome function. 1091 Sep 61

Formaldehyde is a reactive chemical that is commonly used in the production of industrial, laboratory, household, and cosmetic products. The causal association between formaldehyde exposure and increased incidence of cancer led the International Agency for Research on Cancer to classify formaldehyde as a carcinogen. Formaldehyde-induced DNA-protein crosslinks (DPCs) elicit responses involving nucleotide excision repair (NER) and homologous recombination (HR) repair pathways; however, little is known about the cellular and genetic changes that subsequently lead to formaldehyde-induced genotoxic and cytotoxic effects. Herein, investigations of genes that modulate the cytotoxic effects of formaldehyde exposure revealed that of five NER-deficient Chinese Hamster Ovary (CHO) cell lines tested, XPF- and ERCC1-deficient cells were most sensitive to formaldehyde treatment as compared to wild-type cells. Cell cycle analyses revealed that formaldehyde-treated XPF-deficient cells exhibited an immediate G2/M arrest that was associated with altered cell ploidy and apoptosis. Additionally, an elevated number of DNA double-strand breaks (DSBs), chromosomal breaks and radial formation were also observed in XPF-deficient cells following formaldehyde treatment. Formaldehyde-induced DSBs occurred in a replication-dependent, but an XPF-independent manner. However, delayed DSB repair was observed in the absence of XPF function. Collectively, our findings highlight the role of an XPF-dependent pathway in mitigating the sensitivity to formaldehyde-induced DNA damage as evidenced by the increased genomic instability and reduced cell viability in an XPF-deficient background. In addition, centrosome and microtubule abnormalities, as well as enlarged nuclei, caused by formaldehyde exposure are demonstrated in a repair-proficient cell line.
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PMID:Formaldehyde-induced genome instability is suppressed by an XPF-dependent pathway. 2218 32