Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002736 (amyotrophic lateral sclerosis)
 19,048 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

DNA repair mechanisms usually consist of a complex network of enzymatic reactions catalyzed by a large family of mutually interacting gene products. Thus deficiency, alteration or low levels of a single enzyme and/or of auxiliary proteins might impair a repair process. There are several indications suggesting that some enzymes involved both in DNA replication and repair are less abundant if not completely absent in stationary and non replicating cells. Postmitotic brain cell does not replicate its genome and has lower levels of several DNA repair enzymes. This could impair the DNA repair capacity and render the nervous system prone to the accumulation of DNA lesions. Some human diseases clearly characterized by a DNA repair deficiency, such as xeroderma pigmentosum, ataxia-telangiectasia and Cockayne syndrome, show neurodegeneration as one of the main clinical and pathological features. On the other hand there is evidence that some diseases characterized by primary neuronal degeneration (such as amyotrophic lateral sclerosis and Alzheimer disease) may have alterations in the DNA repair systems as well. DNA repair thus appears important to maintain the functional integrity of the nervous system and an accumulation of DNA damages in neurons as a result of impaired DNA repair mechanisms may lead to neuronal degenerations.
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PMID:DNA repair mechanisms in neurological diseases: facts and hypotheses. 146 39

In this Review, familial and sporadic neurological disorders reported to have an etiological link with DNA repair defects are discussed, with special emphasis placed on the molecular link between the disease phenotype and the precise DNA repair defect. Of the 15 neurological disorders listed, some of which have symptoms of progeria, six--spinocerebellar ataxia with axonal neuropathy-1, Huntington's disease, Alzheimer's disease, Parkinson's disease, Down syndrome and amyotrophic lateral sclerosis--seem to result from increased oxidative stress, and the inability of the base excision repair pathway to handle the damage to DNA that this induces. Five of the conditions (xeroderma pigmentosum, Cockayne's syndrome, trichothiodystrophy, Down syndrome, and triple-A syndrome) display a defect in the nucleotide excision repair pathway, four (Huntington's disease, various spinocerebellar ataxias, Friedreich's ataxia and myotonic dystrophy types 1 and 2) exhibit an unusual expansion of repeat sequences in DNA, and four (ataxia-telangiectasia, ataxia-telangiectasia-like disorder, Nijmegen breakage syndrome and Alzheimer's disease) exhibit defects in genes involved in repairing double-strand breaks. The current overall picture indicates that oxidative stress is a major causative factor in genomic instability in the brain, and that the nature of the resulting neurological phenotype depends on the pathway through which the instability is normally repaired.
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PMID:Mechanisms of disease: DNA repair defects and neurological disease. 1734 92

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

A large number of studies indicate that DNA damage and mutation increase with age in human cells and tissues (1). Age-related degenerative disorders in which DNA damage has been invoked include heart disease and neurodegenerative conditions such as Alzheimer's disease, amyotrophic lateral sclerosis, or Parkinson's disease (2, 3). Patients with deficiencies in DNA repair, including xeroderma pigmentosum (XP) (4) and ataxia-telangiectasia (A-T) (5) show characteristic patterns of neurodegeneration (as opposed to a failure of normal development). The implication is that failure of repair can lead to accumulation of damage and degenerative disease. XPs and A-Ts are hypersensitive to specific types of DNA damage, and the degenerative damage in patients is tissue specific. DNA in every tissue, however, is under attack from a range of endogenously formed mutagens, including reactive oxygen species, nitric oxide, reactive metabolites, and breakdown products such as malondialdehyde. A series of repair enzymes recognize and remove these types of DNA damage from the genome. Failure to repair DNA may cause the synthesis of defective proteins, which will repair DNA less efficiently, and in turn lead to propagation of further errors (6). Alternatively, oxidative damage to mitochondrial proteins might cause less efficient processing of oxygen, release of higher levels of reactive oxygen species and increased levels of background DNA damage.
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PMID:Measurement of DNA damage and repair capacity as a function of age using the comet assay. 2235 Dec 71

In order to examine the involvement of oxidative stress in developmental brain disorders, we have performed immunohistochemistry in autopsy brains and enzyme-linked immunosorbent assay (ELISA) in the cerebrospinal fluid and urines of patients. Here, we review our data on the hereditary DNA repair disorders, congenital metabolic errors and childhood-onset neurodegenerative disorders. First, in our studies on hereditary DNA repair disorders, increased oxidative DNA damage and lipid peroxidation were carried out in the degeneration of basal ganglia, intracerebral calcification and cerebellar degeneration in patients with xeroderma pigmentosum, Cockayne syndrome and ataxia-telangiectasia-like disorder, respectively. Next, congenital metabolic errors, apoptosis due to lipid peroxidation seemed to cause neuronal damage in neuronal ceroid-lipofuscinosis. Oxidative stress of DNA combined with reduced expression of antioxidant enzymes occurred in the lesion of the cerebral cortex in mucopolysaccharidoses and mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes. In childhood-onset neurodegenerative disorders, increased oxidative DNA damage and lipid peroxidation may lead to motor neuron death in spinal muscular atrophy like in amyotrophic lateral sclerosis. In patients with dentatorubral-pallidoluysian atrophy, a triplet repeat disease, deposition of oxidative products of nucleosides and reduced expression of antioxidant enzymes were found in the lenticular nucleus. In contrast, the involvement of oxidative stress is not definite in patients with Lafora disease. Rett syndrome patients showed changes of oxidative stress markers and antioxidant power in urines, although the changes may be related to systemic complications.
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PMID:Oxidative stress in developmental brain disorders. 2241 Dec 50

Neuronal inclusions of poly(GA), a protein unconventionally translated from G4C2 repeat expansions in C9ORF72, are abundant in patients with frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) caused by this mutation. To investigate poly(GA) toxicity, we generated mice that exhibit poly(GA) pathology, neurodegeneration and behavioral abnormalities reminiscent of FTD and ALS. These phenotypes occurred in the absence of TDP-43 pathology and required poly(GA) aggregation. HR23 proteins involved in proteasomal degradation and proteins involved in nucleocytoplasmic transport were sequestered by poly(GA) in these mice. HR23A and HR23B similarly colocalized to poly(GA) inclusions in C9ORF72 expansion carriers. Sequestration was accompanied by an accumulation of ubiquitinated proteins and decreased xeroderma pigmentosum C (XPC) levels in mice, indicative of HR23A and HR23B dysfunction. Restoring HR23B levels attenuated poly(GA) aggregation and rescued poly(GA)-induced toxicity in neuronal cultures. These data demonstrate that sequestration and impairment of nuclear HR23 and nucleocytoplasmic transport proteins is an outcome of, and a contributor to, poly(GA) pathology.
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PMID:C9ORF72 poly(GA) aggregates sequester and impair HR23 and nucleocytoplasmic transport proteins. 2699 1