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Abstract
The XPG/ERCC5 endonuclease was originally identified as the causative gene for Xeroderma Pigmentosum complementation group G. Ever since its discovery, in depth biochemical, structural and cell biological studies have provided detailed mechanistic insight into its function in excising DNA damage in nucleotide excision repair, together with the ERCC1–XPF endonuclease. In recent years, it has become evident that XPG has additional important roles in genome maintenance that are independent of its function in NER, as XPG has been implicated in protecting replication forks by promoting homologous recombination as well as in resolving R-loops. Here, we provide an overview of the multitasking of XPG in genome maintenance, by describing in detail how its activity in NER is regulated and the evidence that points to important functions outside of NER. Furthermore, we present the various disease phenotypes associated with inherited XPG deficiency and discuss current ideas on how XPG deficiency leads to these different types of disease.
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2
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Lee TL, Lin PH, Chen PL, Hong JB, Wu CC. Hereditary Hearing Impairment with Cutaneous Abnormalities. Genes (Basel) 2020; 12:43. [PMID: 33396879 PMCID: PMC7823799 DOI: 10.3390/genes12010043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 12/25/2020] [Accepted: 12/26/2020] [Indexed: 12/15/2022] Open
Abstract
Syndromic hereditary hearing impairment (HHI) is a clinically and etiologically diverse condition that has a profound influence on affected individuals and their families. As cutaneous findings are more apparent than hearing-related symptoms to clinicians and, more importantly, to caregivers of affected infants and young individuals, establishing a correlation map of skin manifestations and their underlying genetic causes is key to early identification and diagnosis of syndromic HHI. In this article, we performed a comprehensive PubMed database search on syndromic HHI with cutaneous abnormalities, and reviewed a total of 260 relevant publications. Our in-depth analyses revealed that the cutaneous manifestations associated with HHI could be classified into three categories: pigment, hyperkeratosis/nail, and connective tissue disorders, with each category involving distinct molecular pathogenesis mechanisms. This outline could help clinicians and researchers build a clear atlas regarding the phenotypic features and pathogenetic mechanisms of syndromic HHI with cutaneous abnormalities, and facilitate clinical and molecular diagnoses of these conditions.
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Affiliation(s)
- Tung-Lin Lee
- Department of Medical Education, National Taiwan University Hospital, Taipei City 100, Taiwan;
| | - Pei-Hsuan Lin
- Department of Otolaryngology, National Taiwan University Hospital, Taipei 11556, Taiwan;
- Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei City 100, Taiwan;
| | - Pei-Lung Chen
- Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei City 100, Taiwan;
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei City 100, Taiwan
- Department of Medical Genetics, National Taiwan University Hospital, Taipei 10041, Taiwan
- Department of Internal Medicine, National Taiwan University Hospital, Taipei 10041, Taiwan
| | - Jin-Bon Hong
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei City 100, Taiwan
- Department of Dermatology, National Taiwan University Hospital, Taipei City 100, Taiwan
| | - Chen-Chi Wu
- Department of Otolaryngology, National Taiwan University Hospital, Taipei 11556, Taiwan;
- Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei City 100, Taiwan;
- Department of Medical Genetics, National Taiwan University Hospital, Taipei 10041, Taiwan
- Department of Medical Research, National Taiwan University Biomedical Park Hospital, Hsinchu City 300, Taiwan
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Chikhaoui A, Elouej S, Nabouli I, Jones M, Lagarde A, Ben Rekaya M, Messaoud O, Hamdi Y, Zghal M, Delague V, Levy N, De Sandre-Giovannoli A, Abdelhak S, Yacoub-Youssef H. Identification of a ERCC5 c.2333T>C (L778P) Variant in Two Tunisian Siblings With Mild Xeroderma Pigmentosum Phenotype. Front Genet 2019; 10:111. [PMID: 30838033 PMCID: PMC6383105 DOI: 10.3389/fgene.2019.00111] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 01/30/2019] [Indexed: 11/22/2022] Open
Abstract
Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder due to a defect in the nucleotide excision repair (NER) DNA repair pathway, characterized by severe sunburn development of freckles, premature skin aging, and susceptibility to develop cancers at an average age of eight. XP is an example of accelerated photo-aging. It is a genetically and clinically heterogeneous disease. Eight complementation groups have been described worldwide. In Tunisia, five groups have been already identified. In this work, we investigated the genetic etiology in a family with an atypically mild XP phenotype. Two Tunisian siblings born from first-degree consanguineous parents underwent clinical examination in the dermatology department of the Charles Nicolle Hospital on the basis of acute sunburn reaction and mild neurological disorders. Blood samples were collected from two affected siblings after written informed consent. As all mutations reported in Tunisia have been excluded using Sanger sequencing, we carried out mutational analysis through a targeted panel of gene sequencing using the Agilent HaloPlex target enrichment system. Our clinical study shows, in both patients, the presence of achromic macula in sun exposed area with dermatological feature suggestive of Xeroderma pigmentosum disease. No developmental and neurological disorders were observed except mild intellectual disability. Genetic investigation shows that both patients were carriers of an homozygous T to C transition at the nucleotide position c.2333, causing the leucine to proline amino acid change at the position 778 (p.Leu778Pro) of the ERCC5 gene, and resulting in an XP-G phenotype. The same variation was previously reported at the heterozygous state in a patient cell line in Europe, for which no clinical data were available and was suggested to confer an XP/CS phenotype based on functional tests. This study contributes to further characterization of the mutation spectrum of XP in consanguineous Tunisian families and is potentially helpful for early diagnosis. It also indicates that the genotype-phenotype correlation is not always coherent for patients with mild clinical features. These data therefore suggest that targeted NGS is a highly informative diagnostic strategy, which can be used for XP molecular etiology determination.
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Affiliation(s)
- Asma Chikhaoui
- Laboratoire de Génomique Biomédicale et Oncogénétique, Institut Pasteur de Tunis, Université de Tunis El Manar, Tunis, Tunisia
| | - Sahar Elouej
- Laboratoire de Génomique Biomédicale et Oncogénétique, Institut Pasteur de Tunis, Université de Tunis El Manar, Tunis, Tunisia.,Aix Marseille Univ, Inserm, MMG, U 1251, Marseille, France
| | - Imen Nabouli
- Laboratoire de Génomique Biomédicale et Oncogénétique, Institut Pasteur de Tunis, Université de Tunis El Manar, Tunis, Tunisia
| | - Meriem Jones
- Laboratoire de Génomique Biomédicale et Oncogénétique, Institut Pasteur de Tunis, Université de Tunis El Manar, Tunis, Tunisia.,Service de Dermatologie, Hôpital Charles Nicolle, Tunis, Tunisia
| | - Arnaud Lagarde
- Aix Marseille Univ, Inserm, MMG, U 1251, Marseille, France
| | - Meriem Ben Rekaya
- Laboratoire de Génomique Biomédicale et Oncogénétique, Institut Pasteur de Tunis, Université de Tunis El Manar, Tunis, Tunisia
| | - Olfa Messaoud
- Laboratoire de Génomique Biomédicale et Oncogénétique, Institut Pasteur de Tunis, Université de Tunis El Manar, Tunis, Tunisia
| | - Yosr Hamdi
- Laboratoire de Génomique Biomédicale et Oncogénétique, Institut Pasteur de Tunis, Université de Tunis El Manar, Tunis, Tunisia
| | - Mohamed Zghal
- Service de Dermatologie, Hôpital Charles Nicolle, Tunis, Tunisia
| | | | - Nicolas Levy
- Aix Marseille Univ, Inserm, MMG, U 1251, Marseille, France.,Département de Génétique Médicale, AP-HM, Hôpital la Timone, Marseille, France
| | - Annachiara De Sandre-Giovannoli
- Aix Marseille Univ, Inserm, MMG, U 1251, Marseille, France.,Département de Génétique Médicale, AP-HM, Hôpital la Timone, Marseille, France
| | - Sonia Abdelhak
- Laboratoire de Génomique Biomédicale et Oncogénétique, Institut Pasteur de Tunis, Université de Tunis El Manar, Tunis, Tunisia
| | - Houda Yacoub-Youssef
- Laboratoire de Génomique Biomédicale et Oncogénétique, Institut Pasteur de Tunis, Université de Tunis El Manar, Tunis, Tunisia
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Sabatella M, Theil AF, Ribeiro-Silva C, Slyskova J, Thijssen K, Voskamp C, Lans H, Vermeulen W. Repair protein persistence at DNA lesions characterizes XPF defect with Cockayne syndrome features. Nucleic Acids Res 2018; 46:9563-9577. [PMID: 30165384 PMCID: PMC6182131 DOI: 10.1093/nar/gky774] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 07/19/2018] [Accepted: 08/16/2018] [Indexed: 12/28/2022] Open
Abstract
The structure-specific ERCC1-XPF endonuclease plays a key role in DNA damage excision by nucleotide excision repair (NER) and interstrand crosslink repair. Mutations in this complex can either cause xeroderma pigmentosum (XP) or XP combined with Cockayne syndrome (XPCS-complex) or Fanconi anemia. However, most patients carry compound heterozygous mutations, which confounds the dissection of the phenotypic consequences for each of the identified XPF alleles. Here, we analyzed the functional impact of individual pathogenic XPF alleles on NER. We show that XP-causing mutations diminish XPF recruitment to DNA damage and only mildly affect global genome NER. In contrast, an XPCS-complex-specific mutation causes persistent recruitment of XPF and the upstream core NER machinery to DNA damage and severely impairs both global genome and transcription-coupled NER. Remarkably, persistence of NER factors at DNA damage appears to be a common feature of XPCS-complex cells, suggesting that this could be a determining factor contributing to the development of additional developmental and/or neurodegenerative features in XP patients.
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Affiliation(s)
- Mariangela Sabatella
- Department of Molecular Genetics, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
- Oncode Institute, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
| | - Arjan F Theil
- Department of Molecular Genetics, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
- Oncode Institute, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
| | - Cristina Ribeiro-Silva
- Department of Molecular Genetics, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
- Oncode Institute, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
| | - Jana Slyskova
- Department of Molecular Genetics, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
- Oncode Institute, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
| | - Karen Thijssen
- Department of Molecular Genetics, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
- Oncode Institute, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
| | - Chantal Voskamp
- Department of Molecular Genetics, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
| | - Hannes Lans
- Department of Molecular Genetics, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
- Oncode Institute, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
| | - Wim Vermeulen
- Department of Molecular Genetics, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
- Oncode Institute, Erasmus MC, University Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
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Abstract
Xeroderma pigmentosum-Cockayne syndrome complex is a very rare multisystem degenerative disorder (Orpha: 220295; OMIM: 278730, 278760, 278780, 610651). Published information on XP-CS is mostly scattered throughout the literature. We compiled statistics related to symptom prevalence in XP-CS and have written a clinical description of the syndrome. We also drew on clinical practices used in XP and in Cockayne syndrome without XP to aid management of XP-CS. Extensive searches of the literature identified 43 XP-CS patients. The diagnosis had been confirmed with molecular or biochemical methods in 42 of them. Clinical features of each patient were summarized in spreadsheets and summary statistics were generated from this data. XP patients are classified into complementation groups according to the gene that is mutated. There are four groups in XP-CS, and classification was available for 42 patients. Twenty-one were in the XP-G complementation group, 13 in XP-D, 5 in XP-B, and 3 in XP-F. Overall, the clinical features of XP-CS are very similar to those of CS without XP, with the exception of skin cancers in XP-CS. However, one intriguing finding was that cancer incidence was lower in XP-CS compared to XP alone or XP-neurological disorder. The cancer rate in XP-CS was higher than in CS without XP, an unsurprising finding. There is preliminary evidence for the existence of severity groups in XP-CS, as is the case in CS. Although health problems in XP-CS vary both in severity and in when they the first occur, there was overall homogeneity between all complementation groups and putative severity groups. Severely affected patients met fewer milestones and died at younger ages compared to more mildly affected patients.
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Deep phenotyping of 89 xeroderma pigmentosum patients reveals unexpected heterogeneity dependent on the precise molecular defect. Proc Natl Acad Sci U S A 2016; 113:E1236-45. [PMID: 26884178 DOI: 10.1073/pnas.1519444113] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Xeroderma pigmentosum (XP) is a rare DNA repair disorder characterized by increased susceptibility to UV radiation (UVR)-induced skin pigmentation, skin cancers, ocular surface disease, and, in some patients, sunburn and neurological degeneration. Genetically, it is assigned to eight complementation groups (XP-A to -G and variant). For the last 5 y, the UK national multidisciplinary XP service has provided follow-up for 89 XP patients, representing most of the XP patients in the United Kingdom. Causative mutations, DNA repair levels, and more than 60 clinical variables relating to dermatology, ophthalmology, and neurology have been measured, using scoring systems to categorize disease severity. This deep phenotyping has revealed unanticipated heterogeneity of clinical features, between and within complementation groups. Skin cancer is most common in XP-C, XP-E, and XP-V patients, previously considered to be the milder groups based on cellular analyses. These patients have normal sunburn reactions and are therefore diagnosed later and are less likely to adhere to UVR protection. XP-C patients are specifically hypersensitive to ocular damage, and XP-F and XP-G patients appear to be much less susceptible to skin cancer than other XP groups. Within XP groups, different mutations confer susceptibility or resistance to neurological damage. Our findings on this large cohort of XP patients under long-term follow-up reveal that XP is more heterogeneous than has previously been appreciated. Our data now enable provision of personalized prognostic information and management advice for each XP patient, as well as providing new insights into the functions of the XP proteins.
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Characterization of three XPG-defective patients identifies three missense mutations that impair repair and transcription. J Invest Dermatol 2013; 133:1841-9. [PMID: 23370536 DOI: 10.1038/jid.2013.54] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Only 16 XPG-defective patients with 20 different mutations have been described. The current hypothesis is that missense mutations impair repair (xeroderma pigmentosum (XP) symptoms), whereas truncating mutations impair both repair and transcription (XP and Cockayne syndrome (CS) symptoms). We identified three cell lines of XPG-defective patients (XP40GO, XP72MA, and XP165MA). Patients' fibroblasts showed a reduced post-UVC cell survival. The reduced repair capability, assessed by host cell reactivation, could be complemented by XPG cDNA. XPG mRNA expression of XP165MA, XP72MA, and XP40GO was 83%, 97%, and 82.5%, respectively, compared with normal fibroblasts. XP165MA was homozygous for a p.G805R mutation; XP72MA and XP40GO were both compound heterozygous (p.W814S and p.E727X, and p.L778P and p.Q150X, respectively). Allele-specific complementation analysis of these five mutations revealed that p.L778P and p.W814S retained considerable residual repair activity. In line with the severe XP/CS phenotypes of XP72MA and XP165MA, even the missense mutations failed to interact with the transcription factor IIH subunits XPD and to some extent cdk7 in coimmunoprecipitation assays. Immunofluorescence techniques revealed that the mutations destabilized early recruitment of XP proteins to localized photodamage and delayed their redistribution in vivo. Thus, we identified three XPG missense mutations in the I-region of XPG that impaired repair and transcription and resulted in severe XP/CS.
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Moriwaki S, Takigawa M, Igarashi N, Nagai Y, Amano H, Ishikawa O, Khan SG, Kraemer KH. Xeroderma pigmentosum complementation group G patient with a novel homozygous missense mutation and no neurological abnormalities. Exp Dermatol 2012; 21:304-7. [PMID: 22417308 DOI: 10.1111/j.1600-0625.2012.01446.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We describe an unusual xeroderma pigmentosum (XP) patient with a mutation in XP complementation group G, representing only the third reported Japanese XP-G patient. A 40-year-old men (XP3HM), born from consanguineous parents experienced sun sensitivity and pigmentary changes of sun-exposed skin since childhood. He developed a squamous cell carcinoma on his lower lip at the age of 40. He has neither neurological abnormalities nor Cockayne syndrome. The primary fibroblasts of the patient were hypersensitive to killing by UV (D(0) = 0.6 J/m(2)) and the post-UV unscheduled DNA synthesis was 8% of normal. Host cell reactivation complementation analysis implicated XP complementation group G. We identified a novel homozygous mutation (c.194T>C) in a conserved portion of the XPG(ERCC5) gene, resulting in a predicted amino acid change; p.L65P. We confirmed that this genetic change reduced DNA repair thus linking this mutation to increased skin cancer.
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Schärer OD. XPG: its products and biological roles. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 637:83-92. [PMID: 19181113 DOI: 10.1007/978-0-387-09599-8_9] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Xeroderma pigmetosum patients of the complementation group G are rare. One group of XP-G patients displays a rather mild and typical XP phenotype. Mutations in these patients interfere with the function of XPG in the nucleotide excision repair, where it has a structural role in the assembly of the preincision complex and a catalytic role in making the incision 3' to the damaged site in DNA. Another set of XP-G patient is much more severely affected, displaying combined symptoms of xeroderma pigmentosum and Cockayne syndrome, referred to as XP/CS complex. Although the molecular basis leading to the XP/CS complex has not yet been fully established, current evidence suggests that these patients suffer from a mild defect in transcription in addition to a repair defect. Here, the history of how the XPG gene was discovered, the biochemical properties of the XPG protein and the molecular defects found in XP-G patients and mouse models are reviewed.
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Affiliation(s)
- Orlando D Schärer
- Department of Pharmacological Sciences and Chemistry, Stony Brook University, Stony Brook, NY 11974-3400, USA.
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Thorel F, Constantinou A, Dunand-Sauthier I, Nouspikel T, Lalle P, Raams A, Jaspers NGJ, Vermeulen W, Shivji MKK, Wood RD, Clarkson SG. Definition of a short region of XPG necessary for TFIIH interaction and stable recruitment to sites of UV damage. Mol Cell Biol 2004; 24:10670-80. [PMID: 15572672 PMCID: PMC533987 DOI: 10.1128/mcb.24.24.10670-10680.2004] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
XPG is the human endonuclease that cuts 3' to DNA lesions during nucleotide excision repair. Missense mutations in XPG can lead to xeroderma pigmentosum (XP), whereas truncated or unstable XPG proteins cause Cockayne syndrome (CS), normally yielding life spans of <7 years. One XP-G individual who had advanced XP/CS symptoms at 28 years has been identified. The genetic, biochemical, and cellular defects in this remarkable case provide insight into the onset of XP and CS, and they reveal a previously unrecognized property of XPG. Both of this individual's XPG alleles produce a severely truncated protein, but an infrequent alternative splice generates an XPG protein lacking seven internal amino acids, which can account for his very slight cellular UV resistance. Deletion of XPG amino acids 225 to 231 does not abolish structure-specific endonuclease activity. Instead, this region is essential for interaction with TFIIH and for the stable recruitment of XPG to sites of local UV damage after the prior recruitment of TFIIH. These results define a new functional domain of XPG, and they demonstrate that recruitment of DNA repair proteins to sites of damage does not necessarily lead to productive repair reactions. This observation has potential implications that extend beyond nucleotide excision repair.
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Affiliation(s)
- Fabrizio Thorel
- Department of Microbiology and Molecular Medicine, University Medical Centre, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland
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Emmert S, Slor H, Busch DB, Batko S, Albert RB, Coleman D, Khan SG, Abu-Libdeh B, DiGiovanna JJ, Cunningham BB, Lee MM, Crollick J, Inui H, Ueda T, Hedayati M, Grossman L, Shahlavi T, Cleaver JE, Kraemer KH. Relationship of neurologic degeneration to genotype in three xeroderma pigmentosum group G patients. J Invest Dermatol 2002; 118:972-82. [PMID: 12060391 DOI: 10.1046/j.1523-1747.2002.01782.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We studied three newly diagnosed xeroderma pigmentosum complementation group G patients with markedly different clinical features. An Israeli-Palestinian girl (XP96TA) had severe abnormalities suggestive of the xeroderma pigmentosum/Cockayne syndrome complex including sun sensitivity, neurologic and developmental impairment, and death by age 6 y. A Caucasian girl (XP82DC) also had severe sun sensitivity with neurologic and developmental impairment and died at 5.8 y. In contrast, a mildly affected 14-y-old Caucasian female (XP65BE) had sun sensitivity but no neurologic abnormalities. XP96TA, XP82DC, and XP65BE fibroblasts showed marked reductions in post-ultraviolet cell survival and DNA repair but these were higher in XP65BE than in XP82DC. XP96TA fibroblasts had very low XPG mRNA expression levels whereas XP65BE fibroblasts had nearly normal levels. Host cell reactivation of an ultraviolet-treated reporter assigned all three fibroblast strains to the rare xeroderma pigmentosum complementation group G (only 10 other patients previously reported). XP96TA and XP82DC cells had mutations in both XPG alleles that are predicted to result in severely truncated proteins including stop codons and two base frameshifts. The mild XP65BE patient had an early stop codon mutation in the paternal allele. The XP65BE maternal allele had a single base missense mutation (G2817A, Ala874Thr) that showed residual ability to complement xeroderma pigmentosum complementation group G cells. These observations agree with earlier studies demonstrating that XPG mutations, which are predicted to lead to severely truncated proteins in both alleles, were associated with severe xeroderma pigmentosum/Cockayne syndrome neurologic symptoms. Retaining residual functional activity in one allele was associated with mild clinical features without neurologic abnormalities.
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Affiliation(s)
- Steffen Emmert
- Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA
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Lalle P, Nouspikel T, Constantinou A, Thorel F, Clarkson SG. The founding members of xeroderma pigmentosum group G produce XPG protein with severely impaired endonuclease activity. J Invest Dermatol 2002; 118:344-51. [PMID: 11841555 DOI: 10.1046/j.0022-202x.2001.01673.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Of the eight human genes implicated in xeroderma pigmentosum, defects in XPG produce some of the most clinically diverse symptoms. These range from mild freckling to severe skeletal and neurologic abnormalities characteristic of Cockayne syndrome. Mildly affected xeroderma pigmentosum group G patients have diminished XPG endonuclease activity in nucleotide excision repair, whereas severely affected xeroderma pigmentosum group G/Cockayne syndrome patients produce truncated XPG proteins that are unable to function in either nucleotide excision repair or the transcription-coupled repair of oxidative lesions. The first two xeroderma pigmentosum group G patients, XP2BI and XP3BR, were reported before the relationship between xeroderma pigmentosum group G and Cockayne syndrome was appreciated. Here we provide evidence that both patients produce truncated proteins from one XPG allele. From the second allele, XP2BI generates full-length XPG of 1186 amino acids containing a single L858P substitution that has reduced stability and greatly impaired endonuclease activity. In XP3BR, a single base deletion and alternative splicing at a rare noncanonical AT-AC intron produces a 1185 amino acid protein containing 44 internal non-XPG residues. This protein is stably expressed but it also has greatly impaired endonuclease activity. These four XPG products can thus account for the severe ultraviolet sensitivity of XP2BI and XP3BR fibroblasts. These cells, unlike those from xeroderma pigmentosum group G/Cockayne syndrome patients, are capable of limited transcription-coupled repair of oxidative lesions. Our results suggest that the L858P protein in XP2BI and the almost full-length XPG protein in XP3BR are responsible for this activity and for the absence of severe early onset Cockayne syndrome symptoms in these patients.
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Affiliation(s)
- Philippe Lalle
- Department of Genetics and Microbiology, Centre Médical Universitaire (CMU), Geneva, Switzerland
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13
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Cleaver JE, Thompson LH, Richardson AS, States JC. A summary of mutations in the UV-sensitive disorders: xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy. Hum Mutat 2000; 14:9-22. [PMID: 10447254 DOI: 10.1002/(sici)1098-1004(1999)14:1<9::aid-humu2>3.0.co;2-6] [Citation(s) in RCA: 177] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The human diseases xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy are caused by mutations in a set of interacting gene products, which carry out the process of nucleotide excision repair. The majority of the genes have now been cloned and many mutations in the genes identified. The relationships between the distribution of mutations in the genes and the clinical presentations can be used for diagnosis and for understanding the functions and the modes of interaction among the gene products. The summary presented here represents currently known mutations that can be used as the basis for future studies of the structure, function, and biochemical properties of the proteins involved in this set of complex disorders, and may allow determination of the critical sites for mutations leading to different clinical manifestations. The summary indicates where more data are needed for some complementation groups that have few reported mutations, and for the groups for which the gene(s) are not yet cloned. These include the Xeroderma pigmentosum (XP) variant, the trichothiodystrophy group A (TTDA), and ultraviolet sensitive syndrome (UVs) groups. We also recommend that the XP-group E should be defined explicitly through molecular terms, because assignment by complementation in culture has been difficult. XP-E by this definition contains only those cell lines and patients that have mutations in the small subunit, DDB2, of a damage-specific DNA binding protein.
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Affiliation(s)
- J E Cleaver
- UCSF Cancer Center and Department of Dermatology, University of California, San Francisco 94143-0808, USA.
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Okinaka RT, Perez-Castro AV, Sena A, Laubscher K, Strniste GF, Park MS, Hernandez R, MacInnes MA, Kraemer KH. Heritable genetic alterations in a xeroderma pigmentosum group G/Cockayne syndrome pedigree. Mutat Res 1997; 385:107-14. [PMID: 9447232 DOI: 10.1016/s0921-8777(97)00031-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A search for genetic alterations within the XPG gene has been conducted on skin and blood cells cultured from a newly characterized xeroderma pigmentosum (XP) patient (XP20BE). This patient is the ninth known case that falls into the extremely rare XP complementation group G. Four genetic markers within the XPG gene (including two polymorphisms) demonstrated the Mendelian distribution of this gene from the parents to the patient and to an unaffected sibling. The patient (XP20BE) inherited a G to T transversion from his father in exon 1 of the XPG gene that resulted in the conversion of a glutamic acid at codon 11 to a termination codon. The patient also inherited an XP-G allele from his mother that produces an unstable or poorly expressed message. The cause of the latter defect is still uncertain. In addition to these alterations, XP20BE cDNA contained an mRNA species with a large splicing defect that encompassed a deletion from exon 1 to exon 14. This splicing defect, however, appears to be a naturally occurring low-frequency event that results from abnormal splicing that occurs between certain conserved non-consensus splicing signals within the human XPG gene.
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Affiliation(s)
- R T Okinaka
- Life Sciences Division, Los Alamos National Laboratory, NM 87545, USA.
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Moriwaki S, Stefanini M, Lehmann AR, Hoeijmakers JH, Robbins JH, Rapin I, Botta E, Tanganelli B, Vermeulen W, Broughton BC, Kraemer KH. DNA repair and ultraviolet mutagenesis in cells from a new patient with xeroderma pigmentosum group G and cockayne syndrome resemble xeroderma pigmentosum cells. J Invest Dermatol 1996; 107:647-53. [PMID: 8823375 DOI: 10.1111/1523-1747.ep12584287] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Xeroderma pigmentosum (XP)/Cockayne syndrome (CS) complex is a combination of clinical features of two rare genetic disorders in one individual. A sun-sensitive boy (XP20BE) who had severe symptoms of CS, with dwarfism, microcephaly, retinal degeneration, and mental impairment, had XP-type pigmentation and died at 6 y with marked cachexia (weight 14.5 lb) without skin cancers. We evaluated his cultured cells for characteristic CS or XP DNA-repair abnormalities. The level of ultraviolet (UV)-induced unscheduled DNA synthesis was less than 5% of normal, characteristic of the excision-repair defect of XP. Cell fusion studies indicated that his cells were in XP complementation group G. His cells were hypersensitive to killing by UV, and their post-UV recovery of RNA synthesis was abnormally low, features of both CS and XP. Post-UV survival of plasmid pSP189 in his cells was markedly reduced, and post-UV plasmid mutation frequency was higher than with normal cells, as in both CS and XP. Sequence analysis of the mutated plasmid marker gene showed normal frequency of plasmids with multiple base substitutions, as in CS, and an abnormally increased frequency of G:C-->A:T mutations, a feature of XP. Transfection of UV-treated pRSVcat with or without photoreactivation revealed that his cells, like XP cells, could not repair either cyclobutane pyrimidine dimers or non-dimer photoproducts. These results indicate that the DNA-repair features of the XP20BE (XP-G/CS) cells are phenotypically more like XP cells than CS cells, whereas clinically the CS phenotype is more prominent than XP.
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Affiliation(s)
- S Moriwaki
- Laboratory of Molecular Carcinogenesis, National Cancer Institute, Bethesda, MD 20892, USA
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O'Donovan A, Davies AA, Moggs JG, West SC, Wood RD. XPG endonuclease makes the 3' incision in human DNA nucleotide excision repair. Nature 1994; 371:432-5. [PMID: 8090225 DOI: 10.1038/371432a0] [Citation(s) in RCA: 366] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
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.
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Affiliation(s)
- A O'Donovan
- Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Herts, UK
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17
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O'Donovan A, Scherly D, Clarkson S, Wood R. Isolation of active recombinant XPG protein, a human DNA repair endonuclease. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)33956-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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18
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O'Donovan A, Wood RD. Identical defects in DNA repair in xeroderma pigmentosum group G and rodent ERCC group 5. Nature 1993; 363:185-8. [PMID: 8483505 DOI: 10.1038/363185a0] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Humans with the complementation group G form of the inherited syndrome xeroderma pigmentosum (XP) are hypersensitive to solar ultraviolet light because of a defect in nucleotide-excision repair of DNA. Some individuals are also affected with Cockayne's syndrome, and have neurological abnormalities. Here we report that the DNA repair deficiency of XP-G cell extracts can be corrected by addition of protein fractions from normal cells. Repair proficiency can also be restored by mixing XP-G cell extracts with extracts from different repair-defective cell lines, with one exception. Extracts from cells representing group 5 of a set of ultraviolet-sensitive rodent mutants fail to complement XP-G extracts. XP-G and group 5 correcting activities co-elute after approximately 1,000-fold purification from HeLa cells. An antibody directed against a recombinant fragment of the XP-G complementing protein (XPGC) inhibits excision repair by normal cell extracts, and activity can be restored with an XP-G/group 5 complementing fraction. These data strongly suggest that the XPGC and group 5 correcting (ERCC5) proteins are identical.
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Affiliation(s)
- A O'Donovan
- Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Herts, UK
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Yamamura K, Ichihashi M, Hiramoto T, Ogoshi M, Nishioka K, Fujiwara Y. Clinical and photobiological characteristics of xeroderma pigmentosum complementation group F: a review of cases from Japan. Br J Dermatol 1989; 121:471-80. [PMID: 2696553 DOI: 10.1111/j.1365-2133.1989.tb15514.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A 61-year-old female patient with xeroderma pigmentosum (XP), registered as XP46KO, was assigned to complementation group F by the cell fusion-complementation method. The XP46KO fibroblasts in culture exhibited a defective DNA repair capacity of 10-15% unscheduled DNA synthesis and a 3-fold sensitivity to the lethal effect of 254 nm ultraviolet light compared with normal cells. The patient had mild clinical symptoms consisting of numerous pigmented freckles and a small number of seborrheic keratosis-like papules. She had no skin cancers in the sun-exposed areas of the skin and so far no neurological abnormalities. A review of 11 Japanese group F patients revealed very mild skin symptoms with no ocular or neuro-psychiatric abnormalities. Single skin cancers occurred in only 3 of the 11 patients with an average age of 52 years for their first skin malignancy.
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Affiliation(s)
- K Yamamura
- Department of Dermatology, Kobe University School of Medicine, Japan
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Affiliation(s)
- M M Cohen
- Department of Obstetrics and Gynecology, School of Medicine, University of Maryland, Baltimore
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Norris PG, Hawk JL, Avery JA, Giannelli F. Xeroderma pigmentosum complementation group G--report of two cases. Br J Dermatol 1987; 116:861-6. [PMID: 3620347 DOI: 10.1111/j.1365-2133.1987.tb04906.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Genetic complementation studies allowed assignment of a brother (XP124LO) and sister (XP 125LO), aged 14 and 12 years respectively, to the rare complementation group of classical xeroderma pigmentosum (XP), XP-G. Both patients manifested only mild cutaneous changes, with no UV-induced skin tumours, although abnormal sensitivity to UVB wavelengths was demonstrated by irradiation monochromator skin testing. Physical and neurological development was normal. Measurement of UV-induced unscheduled DNA synthesis in cultured fibroblasts showed reduction of repair synthesis to 14% and 16% of normal in XP124LO and XP125LO, respectively. This contrasts with a reduction to 5% of normal in previously described group G patients, XP2BI and XP3BR, who had correspondingly severe cutaneous and neurological manifestations.
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Nishigori C, Miyachi Y, Takebe H, Imamura S. A case of xeroderma pigmentosum with clinical appearance of dyschromatosis symmetrica hereditaria. Pediatr Dermatol 1986; 3:410-3. [PMID: 3809028 DOI: 10.1111/j.1525-1470.1986.tb00552.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A 9-year-old boy complained of increased freckling on the extremities since very early infancy. Examination showed mottled pigmentation with areas of depigmentation on the backs of the hands and tops of the feet, and less strikingly on the arms and legs. Scattered, small, pigmented freckles on the face were also noticed. The condition was clinically diagnosed as dyschromatosis symmetrica hereditaria (DSH) at first. Unscheduled DNA synthesis was reduced to 66% of the normal value, however, and an ultraviolet sensitivity test by colony formation on fibroblasts revealed moderate sensitivity. Therefore this case was finally diagnosed as xeroderma pigmentosum. It is necessary to study cellular repair capacity to make a precise diagnosis when the distinction is so difficult.
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