Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0043346 (xeroderma pigmentosum)
 2,924 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Six Japanese patients in Hokkaido area were diagnosed as xeroderma pigmentosum (XP) at two University Hospital; one patient, a 29 years old female (XP2AS) at Asahikawa Medical College, and five patients, namely, a 53 years old male (XP1SA), a 45 years old female (XP2SA), a 46 years old female (XP3SA), a 47 years old male (XP4SA) and a 34 years old male (XP5SA) at Hokkaido University School of Medicine. All these XP patients showed mild skin symptoms and had no apparent neurological abnormalities. To identify genetic complementation groups of these patients, DNA repair capacities in skin fibroblasts derived from the patients were analyzed by ultraviolet light (UV)-induced unscheduled DNA synthesis (UDS), and also by colony-forming abilities of UV-irradiated cells incubated with or without caffeine added in post-UV culture medium. The levels of UDS measured by autoradiography in these XP cells irradiated with 20 J/m2 of UV were 67 to 84% of those of normal human fibroblasts. Although one XP cell strain (XP2AS) showed about 2-fold greater sensitivity to killing by UV than normal cells, UV sensitivities of the rest of 5 XP strains were similar or only slightly higher than those of normal cells. However, UV sensitivities of all the 6 XP cell strains markedly increased by addition of 1 mM caffeine in the post-UV incubation medium, a phenomenon characteristic of XP variant cells. We also analyzed post-replication repair in XP1SA cells by sedimentation of newly-synthesized DNA in alkaline sucrose gradient, and found that this strain is defective in this repair system. From these results, we concluded that all the 6 XP strains studied here belong to XP variants.
J Radiat Res 1994 Sep
PMID:Assignment of six patients with xeroderma pigmentosum in Hokkaido area to a variant form. 783 Feb 60

Genetic risk factor(s) for skin cancers have been described in patients with xeroderma pigmentosum (XP). The tumor suppressor gene, p53, is one of the most frequently mutated genes found in human tumors. To evaluate the role of XP-related genetic defects in the p53 gene, skin fibroblast cell lines derived from XP donors were analysed for mutations in exons 5-9 (the regions of gene highly susceptible for mutations) by single-strand conformation polymorphism (SSCP) and nucleotide sequencing. Of the five XP-derived fibroblasts (complementation group A) and two control fibroblast cell lines, only one XP cell line showed an aberrant SSCP banding pattern in the region of the p53 gene (comprising the 7th exon and neighbouring intronic sequences). Nucleotide sequencing of this region confirmed a mutation in the 7th intron adjacent to the 7th exon, which did not affect the RNA splice site. These results suggest that constitutional/germ-line mutations in the p53 gene may not play a role in the occurrence of skin carcinomas in XP patients.
Cancer Lett 1994 Sep 30
PMID:Analysis of the tumor suppressor gene p53 in xeroderma pigmentosum fibroblasts. 792 8

Cytochrome P450 1A1 (CYP1A1) activity is associated with increased susceptibility to lung cancer induced by polycyclic aromatic hydrocarbons such as benzo[a]pyrene (BP). In non-hepatic human tissues, CYP1A1 is the principal enzyme responsible for the metabolic activation of the proximate BP mutagenic metabolite, (-)-benzo[a]pyrene-trans-7,8-dihydrodiol, to (+)-anti-benzo[a]pyrene-trans-7,8-dihydrodiol-9,10-epoxide, the ultimate BP mutagen. We have genetically engineered both DNA repair-deficient (xeroderma pigmentosum group A) and DNA repair-proficient human skin fibroblasts to express human CYP1A1 under control of the inducible mouse metallothionein-I promoter. CYP1A1 activity was induced by CdSO4 and monitored by following the O-deethylation of ethoxy fluorescein ethyl ester or of 7-ethoxyresorufin. Induced CYP1A1 activities were similar in both cell lines and were dependent on CdSO4 concentration and induction time. Maximal CYP1A1 activities were obtained in 4-6 h with 5-7 microM CdSO4. BPD-induced cytotoxicity and hypoxanthine phosphoribosyl transferase mutagenicity were both quantitatively correlated with the level of CYP1A1 activity and were greater in DNA repair-deficient cells than in DNA repair-proficient cells. The results suggest that modestly induced CYP1A1 activity is a risk factor in polycyclic aromatic hydrocarbon-induced carcinogenesis.
Carcinogenesis 1994 Sep
PMID:Cytotoxicity and genotoxicity of (+/-)-benzo[a]pyrene-trans-7,8-dihydrodiol in CYP1A1-expressing human fibroblasts quantitatively correlate with CYP1A1 expression level. 792 75

The proteins that are implicated in the basal transcription of protein coding genes have now been identified. Although little is known about their function, recent data demonstrate the ability of these proteins, previously called class II transcription factors, to participate in other reactions: TBP, the TATA-box binding factor, is involved in class I and III transcription, while TFIIH has been shown to possess components that are involved in the DNA repair mechanism. The involvement of some if not all of the TFIIH subunits in transcription and repair may explain the heterogeneity of the various and sometimes completely unrelated symptoms observed in xeroderma pigmentosum, Cockayne Syndrome and trichothiodystrophy disorders.
Bioessays 1994 Sep
PMID:Transcription by RNA polymerase II: a process linked to DNA repair. 798 Apr 91

The rad16 mutant of Saccharomyces cerevisiae was previously shown to be impaired in removal of UV-induced pyrimidine dimers from the silent mating-type loci (D. D. Bang, R. A. Verhage, N. Goosen, J. Brouwer, and P. van de Putte, Nucleic Acids Res. 20:3925-3931, 1992). Here we show that rad7 as well as rad7 rad16 double mutants have the same repair phenotype, indicating that the RAD7 and RAD16 gene products might operate in the same nucleotide excision repair subpathway. Dimer removal from the genome overall is essentially incomplete in these mutants, leaving about 20 to 30% of the DNA unrepaired. Repair analysis of the transcribed RPB2 gene shows that the nontranscribed strand is not repaired at all in rad7 and rad16 mutants, whereas the transcribed strand is repaired in these mutants at a fast rate similar to that in RAD+ cells. When the results obtained with the RPB2 gene can be generalized, the RAD7 and RAD16 proteins not only are essential for repair of silenced regions but also function in repair of nontranscribed strands of active genes in S. cerevisiae. The phenotype of rad7 and rad16 mutants closely resembles that of human xeroderma pigmentosum complementation group C (XP-C) cells, suggesting that RAD7 and RAD16 in S. cerevisiae function in the same pathway as the XPC gene in human cells. RAD4, which on the basis of sequence homology has been proposed to be the yeast XPC counterpart, seems to be involved in repair of both inactive and active yeast DNA, challenging the hypothesis that RAD4 and XPC are functional homologs.
Mol Cell Biol 1994 Sep
PMID:The RAD7 and RAD16 genes, which are essential for pyrimidine dimer removal from the silent mating type loci, are also required for repair of the nontranscribed strand of an active gene in Saccharomyces cerevisiae. 806 46

A predominant form of the inherited syndrome xeroderma pigmentosum is genetic complementation group C (XP-C). XP-C cells are defective in DNA nucleotide excision repair in the bulk of the genome but can repair transcribed strands of active genes. An activity that can complement the repair deficiency of extracts from XP-C cells has been purified approximately 2,000-fold from HeLa cells. The factor also increases the unscheduled DNA synthesis of XP-C fibroblasts in vivo after microinjection. Hydrodynamic measurements show that the XP-C complementing factor has a native molecular mass of approximately 160 kDa. The factor binds tightly to single-stranded DNA cellulose, eluting in approximately 1.3 M NaCl. No incision or ATPase activity of the protein alone was detected. XP-C protein is involved in an early stage of repair since its presence was required before the start of gap-filling repair synthesis. In vitro complementation was achieved with naked DNA substrates, and so a primary role in processing chromatin to allow access for repair enzymes seems unlikely. Surprisingly, however, extracts from an XP-C cell line introduced some incisions in UV-irradiated DNA; these were unstable in cell extracts and did not lead to complete repair. The data can be explained by a model in which XP-C factor participates in forming one of the repair incisions flanking DNA damage but not the other. In transcribed DNA, its role is subsumed by RNA polymerase and/or transcription coupling factors.
J Biol Chem 1994 Sep 09
PMID:DNA repair defect in xeroderma pigmentosum group C and complementing factor from HeLa cells. 807 26

Humans with a defect in the XPG protein suffer from xeroderma pigmentosum (XP) resulting from an inability to perform DNA nucleotide excision repair properly. Here we show that XPG makes a structure-specific endonucleolytic incision in a synthetic DNA substrate containing a duplex region and single-stranded arms. One strand of the duplex is cleaved at the border with single-stranded DNA. A cut with the same polarity is also made in a bubble structure, at the 3' side of the centrally unpaired region. Normal cell extracts introduce a nick 3' to a platinum-DNA lesion, but an XP-G cell extract is defective in making this incision. These data show that XPG has a direct role in making one of the incisions required to excise a damaged oligonucleotide, by cleaving 3' to DNA damage during nucleotide excision repair.
Nature 1994 Sep 29
PMID:XPG endonuclease makes the 3' incision in human DNA nucleotide excision repair. 793 9

The molecular basis of group A xeroderma pigmentosum (XP) was investigated by Southern blot analysis of genomic DNA and Northern blot analysis of poly (A)+ RNA from patients with group A and atypical group A XP and normal controls. The clones of a patient with group A XP who had typical symptoms showed a G-->C substitution at the 3' splice acceptor site of intron 3, which is the most common mutation in Japanese group A XP patients. On the other hand, one typical group A patient and one atypical group A patient with mild skin lesions and minimal neurological abnormalities showed compound heterozygote for the splicing mutation of intron 3 and the nonsense mutation of exon 6. The other one atypical group A patient showed a homozygote of the nonsense mutation of exon 6, thus suggesting no direct correlationship between severity of neurological complication and DNA abnormality. Northern blot analysis of poly (A)+ RNA revealed that the XPAC mRNAs of group A XP cells were smaller than that of normal controls, and amounts were markedly reduced. Of three atypical group A XP patients, one showed almost normal size and amount of the XPAC mRNA, another showed as small size and reduced amount of the XPAC mRNA, while the third one showed an intermediate type between typical group A XP and normal controls.
Nihon Rinsho 1993 Sep
PMID:[Neurological manifestations and molecular basis of group A xeroderma pigmentosum]. 810 18

A case of malignant melanoma in a medium-sized congenital naevus in a prepubertal girl is presented. Risk factors for developing melanoma during childhood include giant congenital naevi, dysplastic naevus syndrome and xeroderma pigmentosum. The lifetime risk of melanoma associated with giant congenital naevi has been estimated to be 4%-20%; the risk associated with small and medium-sized congenital naevi however remains controversial. In the latter lesions, malignant transformation is considered an almost exclusively postpubertal phenomenon, in contrast to giant congenital naevi where it often occurs prior to puberty. In our patient, malignant transformation in a medium-sized congenital naevus occurred before puberty. We suggest that the true incidence of malignant transformation within these lesions and the time at which it occurs, should be documented by prospective studies and that not only the giant congenital naevi but also the smaller congenital naevi should be considered for prophylactic excision in early childhood.
Eur J Pediatr 1993 Sep
PMID:Prepubertal melanoma in a medium-sized congenital naevus. 822 3

The mammalian ERCC1-encoded polypeptide is required for nucleotide excision repair of damaged DNA and is homologous to Saccharomyces cerevisiae RAD10, which functions in repair and mitotic intrachromosomal recombination. Rodent cells representing repair complementation group 1 have nonfunctional ERCC1. We report that repair of UV-irradiated DNA can be reconstituted by combining rodent group 1 cell extracts with correcting protein from HeLa cells. Background repair was minimized by employing fractionated rodent cell extracts supplemented with human replication proteins RPA and PCNA. Group 1-correcting activity has a native molecular mass of 100 kDa and contains the 33 kDa ERCC1 polypeptide, as well as complementing activities for extracts from rodent group 4 and xeroderma pigmentosum group F (XP-F) cells. Extracts of group 1, group 4 or XP-F cells do not complement one another in vitro, although they complement extracts from other groups. The amount of ERCC1 detectable by immunoblotting is reduced in group 1, group 4 and XP-F extracts. Recombinant ERCC1 from Escherichia coli only weakly corrected the group 1 defect. The data suggest that ERCC1 is part of a functional protein complex with group 4 and XP-F correcting activities. The latter two may be equivalent to one another and analogous to S. cerevisiae RAD1.
EMBO J 1993 Sep
PMID:Co-correction of the ERCC1, ERCC4 and xeroderma pigmentosum group F DNA repair defects in vitro. 825 90


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