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Query: UMLS:C0004135 (ATM)
 13,001 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Aberrations of the long arm of chromosome 11 are among the most common chromosome abnormalities in lymphoproliferative disorders (LPD). Translocations involving BCL1 at 11q13 are strongly associated with mantle cell lymphoma. other nonrandom aberrations, especially deletions and, less frequently, translocations, involving bands 11q21-923 have been identified by chromosome banding analysis. To date, the critical genomic segment and candidate genes involved in these deletions have not been identified. In the present study, we have analyzed tumors from 43 patients with LPD (B-cell chronic lymphocytic leukemia, n = 40; mantle cell lymphoma, n = 3) showing aberrations of bands 11q21-923 by fluorescence in situ hybridization. As probes we used Alu-PCR products from 17 yeast artificial chromosome clones spanning chromosome bands 11q14.3-923.3, including a panel of yeast artificial chromosome clones recognizing a contiguous genomic DNA fragment of approximately 9-10 Mb in bands 11q22.3-923.3. In the 41 tumors exhibiting deletions, we identified a commonly deleted segment in band 11q22.3-923.1; this region is approximately 2-3 Mb in size and contains the genes coding for ATM (ataxia telangiectasia mutated), RDX (radixin), and FDX1 (ferredoxin 1). Furthermore, two translocation break-points were localized to a 1.8-Mb genomic fragment contained within the commonly deleted segment. Thus, we have identified a single critical region of 2-3 Mb in size in which 11q14-923 aberrations in LPD cluster. This provides the basis for the identification of the gene(s) at 11q22.3-923.1 that are involved in the pathogenesis of LPD.
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PMID:Molecular cytogenetic delineation of a novel critical genomic region in chromosome bands 11q22.3-923.1 in lymphoproliferative disorders. 887 24

In mammalian cells, four protein kinases form the PI3-kinase-related protein kinase (PIK) superfamily. These four enzymes-FRAP, DNA-PK, ATM, and ATR-are distinguished by their large size (all are >2500 amino acids), their common primary sequence relatedness through the carboxy-terminal protein kinase domain, and their sequence similarity to the p110 lipid kinase subunit of PI3-kinase. FRAP (FKBP12 and rapamycin-binding protein kinase) participates in mitogenic and growth factor responses in G1 and may regulate specific mRNA translation signals. DNA-PK (DNA-dependent protein kinase), ATM (ataxia telangiectasia mutated), and ATR (ataxia telangiectasia and Rad 3 related) are thought to participate in responses to nuclear cues that activate DNA rearrangements or cell cycle arrests. Recent studies in this protein kinase family indicate an important role for ATM and ATR in a meiotic surveillance mechanism that may regulate proper chromosome transmission.
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PMID:Responses to DNA damage and regulation of cell cycle checkpoints by the ATM protein kinase family. 911 20

Although broken chromosomes can induce apoptosis, natural chromosome ends (telomeres) do not trigger this response. It is shown that this suppression of apoptosis involves the telomeric-repeat binding factor 2 (TRF2). Inhibition of TRF2 resulted in apoptosis in a subset of mammalian cell types. The response was mediated by p53 and the ATM (ataxia telangiectasia mutated) kinase, consistent with activation of a DNA damage checkpoint. Apoptosis was not due to rupture of dicentric chromosomes formed by end-to-end fusion, indicating that telomeres lacking TRF2 directly signal apoptosis, possibly because they resemble damaged DNA. Thus, in some cells, telomere shortening may signal cell death rather than senescence.
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PMID:p53- and ATM-dependent apoptosis induced by telomeres lacking TRF2. 1003 1

Severe combined immunodeficiency (scid) mice are deficient in the enzyme DNA-PK (DNA-dependent protein kinase) as a result of the mutation in the gene encoding the catalytic subunit (DNA-PKcs) of this enzyme. DNA-PKcs is a member of the phosphatidylinositol 3-kinase superfamily, which includes the human protein ATM (ataxia telangiectasia mutated) and the yeast protein Tel1. Using Q-FISH (quantitative fluorescence in situ hybridization), we show here that scid mice from four different genetic backgrounds have, on average, 1.5-2 times longer telomeres than those of corresponding wild-type mice. Our results point to the possibility that DNA-PKcs may, directly or indirectly, be involved in telomere length regulation in mammalian cells.
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PMID:Elongated telomeres in scid mice. 1005 9

The characterization of the rare, radiation-sensitive and cancer-prone syndromes, ataxia telangiectasia and Nijmegen breakage syndrome, has demonstrated that genetic predisposition increases the risk of developing cancer after exposure to ionizing radiation (IR). Molecular analyses of these disorders provide valuable insights into the normal function of these two gene products in the cellular response to IR-induced DNA damage. Their contribution to a cellular radiosensitive phenotype and their role in sporadic cancers can now be fully assessed. For example, the gene ataxia telangiectasia mutated (ATM) has recently been shown to be a tumour suppressor gene in T-cell prolymphocytic leukaemia, and there is increasing evidence that individuals with one mutated ATM or Nijmegen breakage syndrome (NBS1) allele have an increased predisposition to cancer.
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PMID:Radiation, DNA damage and cancer. 1020 48

RAFT1 (rapamycin and FKBP12 target 1; also called FRAP or mTOR) is a member of the ATM (ataxia telangiectasia mutated)-related family of proteins and functions as the in vivo mediator of the effects of the immunosuppressant rapamycin and as an important regulator of messenger RNA translation. In mammalian cells RAFT1 interacted with gephyrin, a widely expressed protein necessary for the clustering of glycine receptors at the cell membrane of neurons. RAFT1 mutants that could not associate with gephyrin failed to signal to downstream molecules, including the p70 ribosomal S6 kinase and the eIF-4E binding protein, 4E-BP1. The interaction with gephyrin ascribes a function to the large amino-terminal region of an ATM-related protein and reveals a role in signal transduction for the clustering protein gephyrin.
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PMID:Interaction of RAFT1 with gephyrin required for rapamycin-sensitive signaling. 1032 25

In response to DNA damage and replication blocks, cells activate pathways that arrest the cell cycle and induce the transcription of genes that facilitate repair. In mammals, ATM (ataxia telangiectasia mutated) kinase together with other checkpoint kinases are important components in this response. We have cloned the rat and human homologs of Saccharomyces cerevisiae Rad 53 and Schizosaccharomyces pombe Cds1, called checkpoint kinase 2 (chk2). Complementation studies suggest that Chk2 can partially replace the function of the defective checkpoint kinase in the Cds1 deficient yeast strain. Chk2 was phosphorylated and activated in response to DNA damage in an ATM dependent manner. Its activation in response to replication blocks by hydroxyurea (HU) treatment, however, was independent of ATM. Using mass spectrometry, we found that, similar to Chk1, Chk2 can phosphorylate serine 216 in Cdc25C, a site known to be involved in negative regulation of Cdc25C. These results suggest that Chk2 is a downstream effector of the ATM-dependent DNA damage checkpoint pathway. Activation of Chk2 might not only delay mitotic entry, but also increase the capacity of cultured cells to survive after treatment with gamma-radiation or with the topoisomerase-I inhibitor topotecan.
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PMID:Mammalian Chk2 is a downstream effector of the ATM-dependent DNA damage checkpoint pathway. 1043 85

Epidemiological evidence points to an increased risk of breast cancer in ataxia telangiectasia (AT) heterozygote women. Previous attempts to screen early onset or familial breast cancer patients failed to confirm an association. The issue of AT and late onset sporadic breast cancer remained unresolved. We screened 47 women who developed later onset, sporadic breast cancer for ataxia telangiectasia mutated (ATM) mutations. No mutations were found.
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PMID:Absence of mutations in the ATM gene in forty-seven cases of sporadic breast cancer. 1047 Oct 49

The cancer-prone neurodegenerative disorder, ataxia telangiectasia (A-T), results from mutations of ATM (ataxia telangiectasia mutated). Individuals with A-T are also hypersensitive to ionizing radiation (IR). Cultured cells from A-T individuals or Atm-/- mice have cell cycle and growth defects and are generally considered radiosensitive. However, it has been shown recently that cell populations in the Atm-/- central nervous system are radioresistant. To define specific IR sensitivities of neural populations, we analyzed Atm-/- astrocytes. Here we show that Atm-/- astrocytes exhibit premature senescence, express constitutively high levels of p21, and have impaired p53 stabilization. However, in contrast to radiosensitive Atm-/- fibroblasts and radioresistant Atm-/- neurons, survival of Atm-/- astrocytes after IR was similar to wild-type astrocytes. Additionally, p53-null astrocytes, but not fibroblasts, were moderately more radioresistant than their wild-type counterparts, suggesting that the deficit in p53 stabilization observed in Atm-null cells is not a measure of radiation susceptibility. Thus, in astrocytes, the function of Atm in cellular growth and radiosensitivity is distinct. These data may have implications for ATM disruption strategies as a radiosensitizing treatment for brain tumors.
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PMID:Ataxia telangiectasia mutated deficiency affects astrocyte growth but not radiosensitivity. 1053 12

The topics of the talks at the annual DNA Repair Network Meeting at City University, London were as usual wide-ranging and provided an absorbing programme. Covered in the 17 talks were the autoproteolysis of O(6)-methylguanine DNA alkyltransferase in Escherichia coli; identification of new intermediates in meiotic recombination in Saccharomyces cerevisiae; the SMC (structural maintenance of chromosomes) family of proteins in Schizosaccharomyces pombe; transposition and V(D)J recombination; mammalian Rad51 foci formation in Rad54, Rad52, XRCC2 and XRCC3 mutants; biochemical analysis of DNA-PK, ATM (ataxia telangiectasia mutated) and ATR (AT related); other human DNA repair deficiencies and their incidence, including xeroderma pigmentosum and a new DNA ligase IV-deficient patient, and back, once again, to alkyltransferase, this time in humans and its manipulation for engineering drug resistance in bone marrow for cancer treatment.
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PMID:Mechanisms of genome maintenance and rearrangement: current research and recent advances in DNA repair and recombination. 1055 96


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