Disease relevance of ERCC5

• The human XPG (ERCC5) gene encodes a large acidic protein that corrects the ultraviolet light sensitivity of cells from both xeroderma pigmentosum complementation group G and rodent ERCC group 5 [1].
• Loss of a nonenzymatic function of XPG results in defective transcription-coupled repair (TCR), Cockayne syndrome (CS), and early death, but the molecular basis for these phenotypes is unknown [2].
• In particular, ERCC5 Asp1104His was associated with increased risk of NHL overall (OR: 1.46; 95% CI: 1.13-1.88; P = 0.004), DLBCL (OR: 1.44; 95% CI: 0.99-2.09; P = 0.058), and also T cell lymphoma [3].
• An XPG DNA repair defect causing mutagen hypersensitivity in mouse leukemia L1210 cells [4].
• Here we report the isolation of full-length XPG as a soluble protein expressed from a recombinant baculovirus [5].

High impact information on ERCC5

• Transcription-coupled repair of 8-oxoguanine: requirement for XPG, TFIIH, and CSB and implications for Cockayne syndrome [6].
• In addition to xeroderma pigmentosum, mutations in the human XPG gene cause early onset Cockayne syndrome (CS) [7].
• This structure suggests the way in which the widely separated conserved regions in the larger nucleotide excision repair proteins, such as human XPG, could assemble into a structure like that of the smaller replication nucleases [8].
• Expression of the human cDNA in vivo restores to normal the sensitivity to ultraviolet light and unscheduled DNA synthesis of lymphoblastoid cells from XP group G, but not CS group A. The XP-G correcting protein XPGC is generated from a messenger RNA of approximately 4 kilobases that is present in normal amounts in the XP-G cell line [9].
• Polarity appears crucial for positioning of the excision repair nucleases XPG and ERCC1-XPF on the DNA [10].

Chemical compound and disease context of ERCC5

• We have studied the role of nucleotide excision repair (NER) in cisplatin DNA damage-induced apoptotic cell death using both normal human fibroblasts and NER-defective xeroderma pigmentosum (XP) XPA and XPG cells [11].
• Transcription-coupled repair of 8-oxoguanine: requirement for XPG, TFIIH, and CSB and implications for Cockayne syndrome [12].
• Cells from Cockayne syndrome patients with mutations in the XPG gene show approximately 2-fold reduced global repair of thymine glycol [13].
• The recombinant baculovirus produced XPG with a mobility of approximately 185 kDa in a denaturing polyacrylamide gel [14].
• The data show that ERCC5, encoding Xeroderma pigmentosum protein G (XPG), essential for DNA excision repair, and ribonucleotide reductase subunit M1 (RNRM1), encoding a gene necessary for providing the nucleotides needed for DNA repair, were down-regulated in cells treated with diazinon [15].

Biological context of ERCC5

• Human ERCC5 cDNA-cosmid complementation for excision repair and bipartite amino acid domains conserved with RAD proteins of Saccharomyces cerevisiae and Schizosaccharomyces pombe [16].
• The complete deduced amino acid sequence of ERCC5 was reconstructed from several cDNA clones encoding a predicted protein of 1,186 amino acids [16].
• The cloned human sequences exhibited 100% concordance with the locus designated genetically as ERCC5 located on human chromosome 13q [17].
• Analysis of transformants derived from the active cosmid pairs showed that the functional 32-kbp ERCC5 gene was reconstructed by homologous intercosmid recombination [17].
• Transfection with mouse ERCC5 cDNA restored normal levels of UV resistance to XL216 cells [18].

Anatomical context of ERCC5

• ERCC5 corrects the excision repair deficiency of Chinese hamster ovary cell line UV135, of complementation group 5 [17].
• Microinjection of ERCC5 cDNA specifically restored the defect of xeroderma pigmentosum group G cells (XP-G) as measured by unscheduled DNA synthesis, and XP-G cells stably transformed with ERCC5 cDNA showed nearly normal UV resistance [18].
• Comparison of the IC50 values for irofulven, cisplatin, and ecteinascidin 743 with the expression levels of ERCC1, XPD, and XPG genes in different solid tumor cell lines shows no correlation between the expression levels of any of the three nucleotide excision repair proteins and the sensitivity to ecteinascidin 743 [19].
• Immunofluorescence analysis using antibodies directed against the essential repair factors proliferating cell nuclear antigen and XPG did not reveal labeling of the coiled body in either untreated cells or cells irradiated with UV light, arguing that coiled bodies are probably not involved in DNA repair mechanisms [20].
• Using beta-galactosidase-XPG fusion constructs (beta-gal-XPG) transfected into HeLa cells, we have identified a single region of XPG that is evidently responsible both for foci formation and for the UV dynamic response [21].

Associations of ERCC5 with chemical compounds

• A conserved arginine in FEN-1 (Arg339) and XPG (Arg992) was found to be crucial for PCNA binding activity [22].
• In contrast, expression of the XPG endonuclease was correlated with the cytotoxicity for irofulven and, to a lesser degree, for cisplatin [19].
• We have observed that mutation of the XPG gene drastically reduced the level and rate of global removal of thymine glycol (induced by 2-Gy irradiation), and there was no evidence for an inducible response [23].
• This changed the highly conserved Pro-72 to a histidine, a substitution that would be expected to seriously impair the 3' endonuclease function of XPG in nucleotide excision repair [24].
• In addition, exposure of XPA and XPG fibroblasts to UV (5, 10 or 20 J/m2) followed by incubation without araC resulted in a strong upregulation of p53 [25].

Physical interactions of ERCC5

• We show that XPG interacts with elongating RNA polymerase II (RNAPII) in the cell and binds stalled RNAPII ternary complexes in vitro both independently and cooperatively with CSB [2].
• XPG binding stabilizes the NER preincision complex and is essential for the 5' incision by the ERCC1/XPF endonuclease [26].
• Using extracts from A23187-treated cells, a similar conclusion was drawn except that the inhibitory effect of cytosolic extracts on UVDRP binding was completely diminished by proteinase K [27].

Regulatory relationships of ERCC5

• Recruitment of the Nucleotide Excision Repair Endonuclease XPG to Sites of UV-Induced DNA Damage Depends on Functional TFIIH [26].

Other interactions of ERCC5

• During nucleotide excision repair in human cells, a damaged DNA strand is cleaved by two endonucleases, XPG on the 3' side of the lesion and ERCC1-XPF on the 5' side [28].
• The results obtained from our immunoprecipitation experiment further demonstrated that the ATM protein interacted with the TFIIH basal transcription factor and the XPG protein of the NER pathway [11].
• The human cell lines, defective in nucleotide excision protein, such as xeroderma pigmentosum (XP) A, XPD, and XPG, excised Ultraviolet C-induced adducts less rapidly than normal fibroblasts, but excised As(2)O(3) adducts at the same rate as the normal cells [29].
• A moderate increase in the levels of SSBs was also found in individuals with the homozygous XPG exon 15 wild type (GG) and heterozygous (GC) genotypes in comparison to those with the homozygous (CC) genotype (P=0.066) and in individuals with low activity EPHX1 genotype in comparison to those with high activity genotype [30].
• Such dispersal requires functional XPA, XPF and XPG proteins [31].

Analytical, diagnostic and therapeutic context of ERCC5

• The genomic DNA fragment encoding the excision repair gene, ERCC5, was mapped by direct R-banding fluorescence in situ hybridization [32].
• XPGDelta184-210 and XPGDelta554-730 are not observed at sites of local UV damage in living cells by immunofluorescence, suggesting that the weakened interaction between XPG and TFIIH results in an NER reaction with altered kinetics [33].
• Using confocal microscopy, we have localized the immunofluorescent, antigenic signal of XPG protein to foci throughout the cell nucleus [21].
• Indirect immunofluorescence studies demonstrated that the recombinant full-length XPG protein was expressed predominantly as a nuclear protein [14].
• Northern blot analysis revealed that XPG mRNA was more extensively transcribed in CSB cells treated with HuIFN-beta than in those without HuIFN-beta treatment [34].

References