Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

DNA helicases are required for virtually every aspect of DNA metabolism, including replication, repair, recombination and transcription. A comprehensive description of these essential biochemical processes requires detailed understanding of helicase mechanisms. These enzymes are ubiquitous, having been identified in viruses, prokaryotes and eukaryotes. Disease states, such as xeroderma pigmentosum, Cockayne's syndrome, Bloom's syndrome and Werner's syndrome, have been linked to defects in specific genes coding for DNA helicases. Helicases have been placed into different subfamilies based on sequence comparison. The largest subgroups are termed superfamily 1 and superfamily 2. A proposed mechanism for helicases in these classes has been described in terms of an 'inchworm model'. The inchworm model includes conformational changes driven by ATP binding and hydrolysis that allow unidirectional translocation along DNA. A monomeric form of the enzyme is proposed to have two DNA-binding sites that enable sequential steps of DNA binding and release. Significant differences exist between helicases in important aspects of the models such as the oligomerization state of the enzyme with some helicases functioning as monomers, some as dimers and others as higher-order oligomers.
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PMID:DNA unwinding and protein displacement by superfamily 1 and superfamily 2 helicases. 1693 80

DNA helicases are molecular motors that catalyse the unwinding of energetically unstable structures into single strands and have therefore an essential role in nearly all metabolism transactions. Defects in helicase function can result in human syndromes in which predisposition to cancer and genomic instability are common features. So far different helicase genes have been found associated in 8 such disorders. RecQ helicases are a family of conserved enzymes required for maintaining the genome integrity that function as suppressors of inappropriate recombination. Mutations in RecQ4, BLM and WRN give rise to various disorders: Bloom syndrome, Rothmund-Thomson syndrome, and Werner syndrome characterized by genomic instability and increased cancer susceptibility. The DNA helicase BRIP1/BACH1 is involved in double-strand break repair and is defective in Fanconi anemia complementation group J. Mutations in XPD and XPB genes can result in xeroderma pigmentosum, Cockayne syndrome and trichothiodystrophy, three genetic disorders with different clinical features but with association of transcription and NER defects. This review summarizes our current knowledge on the diverse biological functions of these helicases and the molecular basis of the associated diseases.
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PMID:[DNA helicases and human diseases]. 1715 31

A comparative evaluation is reported of pro-oxidant states in 82 patients with ataxia telangectasia (AT), Bloom syndrome (BS), Down syndrome (DS), Fanconi anemia (FA), Werner syndrome (WS), and xeroderma pigmentosum (XP) vs 98 control donors. These disorders display cancer proneness, and/or early aging, and/or other clinical features. The measured analytes were: (a) leukocyte and urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), (b) blood glutathione (GSSG and GSH), (c) plasma glyoxal (Glx) and methylglyoxal (MGlx), and (d) some plasma antioxidants [uric acid (UA) and ascorbic acid (AA)]. Leukocyte 8-OHdG levels ranked as follows: WS>BS approximately FA approximately XP>DS approximately AT approximately controls. Urinary 8-OHdG levels were significantly increased in a total of 22 patients with BS, FA, or XP vs 47 controls. The GSSG:GSH ratio was significantly increased in patients with WS and in young (< or =15 years) patients with DS or with FA and decreased in older patients with DS or FA and in AT, BS, and XP patients. The plasma levels of Glx and/or MGlx were significantly increased in patients with WS, FA, and DS. The UA and AA levels were significantly increased in WS and DS patients, but not in AT, FA, BS, nor XP patients. Rationale for chemoprevention trials is discussed.
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PMID:Different patterns of in vivo pro-oxidant states in a set of cancer- or aging-related genetic diseases. 1805 16

Despite their rarity, diseases of premature aging, or "progeroid" syndromes, have provided important insights into basic mechanisms that may underlie cancer and normal aging. In this review, we highlight these recent developments in Hutchinson-Gilford progeria syndrome (HGPS), Werner syndrome, Bloom syndrome, Cockayne syndrome, trichothiodystrophy, ataxia-telangiectasia, Rothmund-Thomson syndrome, and xeroderma pigmentosum. Though they are caused by different mutations in various genes and often result in quite disparate phenotypes, deciphering the molecular bases of these conditions has served to highlight their underlying basic similarities. Studies of progeroid syndromes, particularly HGPS, the most dramatic form of premature aging, have contributed to our knowledge of fundamental processes of importance to skin biology, including DNA transcription, replication, and repair, genome instability, cellular senescence, and stem-cell differentiation.
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PMID:From the rarest to the most common: insights from progeroid syndromes into skin cancer and aging. 1938 78

Progeroid syndromes are a group of diseases characterized by signs of premature aging. These syndromes comprise diseases such as Werner syndrome, Bloom syndrome, Rothmund-Thomson syndrome, Hutchinson-Gilford syndrome, Fanconi anemia, and ataxia-telangiectasia, as well as xeroderma pigmentosum, trichothiodystrophy, and Cockayne syndrome. Clinical symptoms of premature aging are skin atrophy with loss of cutaneous elasticity, dysfunction of cutaneous appendices, degeneration of the central nervous system and an increased susceptibility for malignant tumors. Genetic defects in the repair of DNA damage can lead to progeroid syndromes, and it is becoming increasingly evident that direct DNA damage and indirect damage by highly reactive oxygen species play central roles in aging. The clinical signs of progeroid syndromes and the molecular aspects of UV (ultraviolet radiation)-induced oxidative stress in aging are discussed.Journal of Investigative Dermatology Symposium Proceedings (2009) 14, 8-14; doi:10.1038/jidsymp.2009.6.
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PMID:Progeroid syndromes and UV-induced oxidative DNA damage. 1967 46

Complete loss of function in the WRN: RecQ3 DNA/RNA helicase gene causes Werner Syndrome (WS). WS patients with genetic instability manifest an early onset of age-related diseases including diabetes mellitus (DM), osteoporosis, atherosclerosis, and malignancy as well as early death. In 1,420 patients, WS was reported to be associated with chromosomal abnormality syndrome and other genetic diseases including Klinefelter syndrome in 2 patients, retinitis pigmentosa in 3, Wilson's disease in 1, xeroderma pigmentosum in 3, and porokeratosis Mibelli in 1. These clinical findings may support the concept of genetic instability in WS.
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PMID:Syndrome-causing mutations in Werner syndrome. 2010 20

Helicases are ubiquitous enzymes that are vital to all living organisms. They are motor proteins that move in a specific direction along the nucleic acid and unwind the nucleic acid (DNA and RNA). ATP hydrolysis provides energy for helicase translocation and unwinding. The unwinding process provides ssDNA intermediates necessary for replication, recombination, and repair. Mutations in specific DNA helicases can lead to disruption in DNA metabolism. For example, mutations in helicases genes resulted in diseases such as xeroderma pigmentosum, cockayne's syndrome, Bloom's syndrome, and Werner's syndrome. During unwinding, helicases are most likely to encounter proteins while moving along the nucleic acid. Several different research groups have demonstrated that helicases shift or displace proteins from one nucleic acid-bound location to another. These protein-protein collisions could result in displacement of proteins from nucleic acid or dissociation of helicase from nucleic acid. This report describes several different methods developed to study protein displacement by DNA and RNA helicases.
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PMID:Protein displacement by helicases. 2022 43

The accumulation of DNA damage has been widely implicated in premature aging and neurodegeneration. Progeroid syndromes with defects in the cellular response to DNA damage suggest that progressive genome instability represents an important aspect of the aging process. Moreover, most of the major neurodegenerative diseases are characterized by the accumulation of neuronal DNA damage, suggesting that impaired DNA repair mechanisms might be relevant to both premature aging and neurodegeneration. Two progeroid syndromes, Hutchinson-Gilford progeria syndrome and Werner's syndrome, are characterized by clinical features mimicking physiological aging at an early age and molecular studies have implicated decreased cell proliferation and altered DNA-damage responses as common causal mechanisms in the pathogenesis of both diseases. Defects in nucleotide excision repair cause three distinct human diseases: xeroderma pigmentosum, Cockayne's syndrome and trichothiodystrophy; each of them is characterized by premature onset of pathologies that overlap with those associated with old age in humans. Increasing evidence also suggests that an impaired DNA repair, particularly the base excision repair pathway, might play a fundamental role in the development of age-related neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and Huntington' s disease. Here, we review the current knowledge on the role of DNA repair in premature aging and neurodegenerative diseases.
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PMID:DNA repair in premature aging disorders and neurodegeneration. 2029 65

Deficiency in repair of nuclear and mitochondrial DNA damage has been linked to several neurodegenerative disorders. Many recent experimental results indicate that the post-mitotic neurons are particularly prone to accumulation of unrepaired DNA lesions potentially leading to progressive neurodegeneration. Nucleotide excision repair is the cellular pathway responsible for removing helix-distorting DNA damage and deficiency in such repair is found in a number of diseases with neurodegenerative phenotypes, including Xeroderma Pigmentosum and Cockayne syndrome. The main pathway for repairing oxidative base lesions is base excision repair, and such repair is crucial for neurons given their high rates of oxygen metabolism. Mismatch repair corrects base mispairs generated during replication and evidence indicates that oxidative DNA damage can cause this pathway to expand trinucleotide repeats, thereby causing Huntington's disease. Single-strand breaks are common DNA lesions and are associated with the neurodegenerative diseases, ataxia-oculomotor apraxia-1 and spinocerebellar ataxia with axonal neuropathy-1. DNA double-strand breaks are toxic lesions and two main pathways exist for their repair: homologous recombination and non-homologous end-joining. Ataxia telangiectasia and related disorders with defects in these pathways illustrate that such defects can lead to early childhood neurodegeneration. Aging is a risk factor for neurodegeneration and accumulation of oxidative mitochondrial DNA damage may be linked with the age-associated neurodegenerative disorders Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. Mutation in the WRN protein leads to the premature aging disease Werner syndrome, a disorder that features neurodegeneration. In this article we review the evidence linking deficiencies in the DNA repair pathways with neurodegeneration.
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PMID:DNA repair deficiency in neurodegeneration. 2155 Mar 79

XPG is a structure-specific endonuclease required for nucleotide excision repair (NER). XPG incision defects result in the cancer-prone syndrome xeroderma pigmentosum, whereas truncating mutations of XPG cause the severe postnatal progeroid developmental disorder Cockayne syndrome. We show that XPG interacts directly with WRN protein, which is defective in the premature aging disorder Werner syndrome, and that the two proteins undergo similar subnuclear redistribution in S phase and colocalize in nuclear foci. The co-localization was observed in mid- to late S phase, when WRN moves from nucleoli to nuclear foci that have been shown to contain both protein markers of stalled replication forks and telomeric proteins. We mapped the interaction between XPG and WRN to the C-terminal domains of each, and show that interaction with the C-terminal domain of XPG strongly stimulates WRN helicase activity. WRN also possesses a competing DNA single-strand annealing activity that, combined with unwinding, has been shown to coordinate regression of model replication forks to form Holliday junction/chicken foot intermediate structures. We tested whether XPG stimulated WRN annealing activity, and found that XPG itself has intrinsic strand annealing activity that requires the unstructured R- and C-terminal domains but not the conserved catalytic core or endonuclease activity. Annealing by XPG is cooperative, rather than additive, with WRN annealing. Taken together, our results suggest a novel function for XPG in S phase that is, at least in part, performed coordinately with WRN, and which may contribute to the severity of the phenotypes that occur upon loss of XPG.
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PMID:The DNA repair endonuclease XPG interacts directly and functionally with the WRN helicase defective in Werner syndrome. 2191 2


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