Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004135 (ATM)
 13,001 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

SPO11 introduces double-strand breaks (DSBs) that trigger the phosphorylation of H2AX during meiotic prophase. In mice, SPO11 is strictly required for initiation of meiotic recombination and synapsis, yet SPO11 is still considered to be dispensable for sex-body formation in mouse spermatocytes. We provide conclusive evidence showing that functional SPO11, and consequently recombination and synapsis, are required for phosphorylation of H2AX in the X-Y chromatin and for sex-body formation in mouse spermatocytes. We investigated the role in meiosis of the three kinases [ATM (ataxia telangiectasia mutated), ATR (ataxia-telangiectasia- and Rad-3-related) and DNA-PKcs (DNA-dependent-protein-kinase catalytic subunit)] known to phosphorylate H2AX in mitotic cells. We found that DNA-PKcs can be ruled out as an essential kinase in this process, whereas ATM is strictly required for the chromatin-wide phosphorylation of H2AX occurring in leptotene spermatocytes in response to DSBs. Remarkably, we discovered that Spo11 heterozygosity can rescue the prophase-I-arrest characteristic of ATM-deficient spermatocytes. Characterization of the rescued Atm-/- Spo11+/- mutant indicates that ATM is dispensable for sex-body formation and phosphorylation of H2AX in this subnuclear domain. The co-localization of ATR, phosphorylated H2AX and the sex chromatin observed in the Atm-/- Spo11+/- mutant, along with ATR transcription kinetics during the first wave of spermatogenesis, confirm and expand recent findings indicating that ATR is the kinase involved in H2AX phosphorylation in the sex body.
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PMID:SPO11 is required for sex-body formation, and Spo11 heterozygosity rescues the prophase arrest of Atm-/- spermatocytes. 1599 65

Ataxia telangiectasia (A-T) is an autosomal recessive disease caused by loss of function of the serine/threonine protein kinase ATM (ataxia telangiectasia mutated). A-T patients have a 250-700-fold increased risk of developing lymphomas and leukemias which are typically highly invasive and proliferative. In addition, a subset of adult acute lymphoblastic leukemias and aggressive B-cell chronic lymphocytic leukemias that occur in the general population show loss of heterozygosity for ATM. To define the specific role of ATM in lymphomagenesis, we studied T-cell lymphomas isolated from mice with mutations in ATM and/or p53 using cytogenetic analysis and mRNA transcriptional profiling. The analyses identified genes misregulated as a consequence of the amplifications, deletions and translocation events arising as a result of ATM loss. A specific recurrent disruption of the granzyme gene family locus was identified resulting in an aberrant granzyme B/C fusion product. The combined application of cytogenetic and gene expression approaches identified specific loci and genes that define the pathway of initiation and progression of lymphoreticular malignancies in the absence of ATM.
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PMID:Aberrant recombination involving the granzyme locus occurs in Atm-/- T-cell lymphomas. 1608 85

Transient transfection has been widely used in many biological applications including gene regulation and DNA repair, but, so far, little attention has been paid to cellular responses induced by the transfected DNA. Here, we report that double-stranded (ds) DNA introduced into mammalian cells induced expression of a variety of genes involved in DNA damage signaling and DNA repair. The expression profile of the induced genes was highly dependent on the cell type, suggesting interactions between exogenous dsDNA and cellular proteins. Moreover, each cell line elicited a markedly different level of intrinsic cellular responses to the introduced dsDNA. Furthermore, the presence of single-stranded oligonucleotides or short duplexes consisting of two complementary oligonucleotides did not affect cellular response, indicating that the induction was highly dependent on the structure and length of exogenous DNA. The extent of induction of DNA damage, signaling and DNA repair activities correlated to episomal and chromosomal gene correction frequencies. In addition, the presented data indicate that the presence of exogenous dsDNA triggered a DNA damage response by activation of ATR (ataxia telangiectasia-Rad3-related) but not ATM (ataxia telangiectasia mutated) pathway.
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PMID:Differential cellular responses to exogenous DNA in mammalian cells and its effect on oligonucleotide-directed gene modification. 1617 21

Defective elimination of autoreactive cells is thought to play a role in the development of autoimmune diseases including multiple sclerosis (MS). We examined the activation of the ATM-CHK2-p53 pathway in MS patients after subjecting their peripheral blood mononuclear cells to gamma-irradiation. We found that peripheral blood mononuclear cells from a subset of MS patients show resistance to cell death induced by irradiation. This defect is due to impaired constitutive expression and activation of ATM (ataxia telangiectasia mutated), resulting in impaired stabilization of p53. We predict that these fundamental defects likely alter the regulation of the immune population of cells in MS and may contribute to the development or progression of the disease.
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PMID:Defective ATM-p53-mediated apoptotic pathway in multiple sclerosis. 1617 12

Progression from G(1) to S is essential for polyomavirus DNA replication and depends on the interaction of large T with the retinoblastoma gene product pRb. This virus-induced replication pathway is accompanied by p53 activation resembling a DNA damage response (12). We sought to determine whether this pathway depends in part on activation of the ATM (ataxia telangiectasia mutated) kinase and whether the virus gains advantages from this pathway beyond that of entry into S. We show that polyomavirus infection activates the S- and G(2)-phase checkpoints in primary as well as established mouse cells. Infected cells undergo a prolonged S phase compared to uninfected serum-stimulated cells and show no evidence of a G(2)-->M transition before lytic death ensues. Infection is accompanied by increases in ATM activity in vitro and in the level of ATM-S1981-P in vivo. The incubation of infected cells with caffeine, a known ATM inhibitor, did not block entry into S but reduced the rate of viral compared to cellular DNA synthesis. Importantly, caffeine lowered the yields of viral DNA an average of 3- to 6-fold and those of infectious virus by as much as 10-fold. Virus yields were 10-fold lower in ATM (-/-) p53(-/-) than in ATM(+/+) p53(-/-) mouse embryo fibroblasts, indicating a p53-independent role of ATM in productive infection. Replacement of the normal SMC1 (structural maintenance of chromosomes, or cohesin) protein, a critical ATM substrate in the DNA repair pathway, with its phosphorylation mutant SMC1(S957AS966A) also lowered virus yields by roughly 90%. We suggest that polyomavirus activates and utilizes a component(s) of an ATM pathway of DNA repair to prolong S phase and aid its own replication.
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PMID:Induction and utilization of an ATM signaling pathway by polyomavirus. 1618 3

ATM kinase, the product of the ataxia telangiectasia mutated (Atm) gene, is activated by genomic damage. ATM plays a crucial role in cell growth and development. Here we report that primary astrocytes isolated from ATM-deficient mice grow slowly, become senescent, and die in culture. However, before reaching senescence, these primary Atm(-/-) astrocytes, like Atm(-/-) lymphocytes, show increased spontaneous DNA synthesis. These astrocytes also show markers of oxidative stress and endoplasmic reticulum (ER) stress, including increased levels of heat shock proteins (HSP70 and GRP78), malondialdehyde adducts, Cu/Zn superoxide dismutase, procaspase 12 cleavage, and redox-sensitive phosphorylation of extracellular signal-regulated protein kinase 1 and 2 (ERK1/2). In addition, HSP70 and ERK1/2 phosphorylation are upregulated in the cerebella of ATM-deficient mice. This increase in ERK1/2 phosphorylation is seen primarily in cerebellar astrocytes, or Bergmann glia, near degenerating Purkinje cells. ERK1/2 activation and astrogliosis are also found in other parts of the brain, for example, the cortex. We conclude that ATM deficiency induces intrinsic growth defects, oxidative stress, ER stress, and ERKs activation in astrocytes.
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PMID:ATM deficiency induces oxidative stress and endoplasmic reticulum stress in astrocytes. 1618 15

The multifunctional transcription factor TFII-I is tyrosine phosphorylated in response to extracellular growth signals and transcriptionally activates growth-promoting genes. However, whether activation of TFII-I also directly affects the cell cycle profile is unknown. Here we show that under normal growth conditions, TFII-I is recruited to the cyclin D1 promoter and transcriptionally activates this gene. Most strikingly, upon cell cycle arrest resulting from genotoxic stress and p53 activation, TFII-I is ubiquitinated and targeted for proteasomal degradation in a p53- and ATM (ataxia telangiectasia mutated)-dependent manner. Consistent with a direct role of TFII-I in cell cycle regulation and cellular proliferation, stable and ectopic expression of wild-type TFII-I increases cyclin D1 levels, resulting in accelerated entry to and exit from S phase, and overcomes p53-mediated cell cycle arrest, despite radiation. We further show that the transcriptional regulation of cyclin D1 and cell cycle control by TFII-I are dependent on its tyrosine phosphorylation at positions 248 and 611, sites required for its growth signal-mediated transcriptional activity. Taken together, our data define TFII-I as a growth signal-dependent transcriptional activator that is critical for cell cycle control and proliferation and further reveal that genotoxic stress-induced degradation of TFII-I results in cell cycle arrest.
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PMID:Inhibition of TFII-I-dependent cell cycle regulation by p53. 1631 17

ATM (ataxia telangiectasia mutated) is required for the early response to DNA-damaging agents such as ionizing radiation (IR) that induce DNA double-strand breaks. Cells deficient in ATM are extremely sensitive to IR. It has been shown that IR induces immediate phosphorylation of ATM at Ser(1981), leading to catalytic activation of the protein. We recently isolated a novel BRCA1-associated protein, BAAT1 (BRCA1-associated protein required for ATM activation-1), by yeast two-hybrid screening and found that BAAT1 also binds to ATM, localizes to double-strand breaks, and is required for Ser(1981) phosphorylation of ATM. Small interfering RNA-mediated stable or transient reduction of BAAT1 resulted in decreased phosphorylation of both ATM at Ser(1981) and CHK2 at Thr(68). Treatment of BAAT1-depleted cells with okadaic acid greatly restored phosphorylation of ATM at Ser(1981), suggesting that BAAT1 is involved in the regulation of ATM phosphatase. Protein phosphatase 2A-mediated dephosphorylation of ATM was partially blocked by purified BAAT1 in vitro. Significantly, acute loss of BAAT1 resulted in increased p53, leading to apoptosis. These results demonstrate that DNA damage-induced ATM activation requires a coordinated assembly of BRCA1, BAAT1, and ATM.
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PMID:ATM activation by ionizing radiation requires BRCA1-associated BAAT1. 1645 82

Stalled replication forks induce p53, which is required to maintain the replication checkpoint. In contrast to the well-established mechanisms of DNA damage-activated p53, the downstream effectors and upstream regulators of p53 during replication blockade remain to be deciphered. Hydroxyurea triggered accumulation of p53 through an increase in protein stability. The requirement of p53 accumulation for the replication checkpoint was not due to p21(CIP1/WAF1) as its down-regulation with short-hairpin RNA did not affect the checkpoint. Similar to DNA damage, stalled replication triggered the activation of the MRN-ataxia telangiectasia mutated (ATM)/ATM and Rad3-related-CHK1/CHK2 axis. Down-regulation of CHK1 or CHK2, however, reduced p53 basal expression but not the hydroxyurea-dependent induction. Moreover, p53 was still stabilized in ataxia telangiectasia cells or in cells treated with caffeine, suggesting that ATM was not a critical determinant. These data also suggest that the functions of ATM, CHK1, and CHK2 in the replication checkpoint were not through the p53-p21(CIP1/WAF1) pathway. In contrast, induction of p53 by hydroxyurea was defective in cells lacking NBS1 and BLM. In this connection, the impaired replication checkpoint in several other genetic disorders has little correlation with the ability to stabilize p53. These data highlighted the different mechanisms involved in the stabilization of p53 after DNA damage and stalled replication forks.
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PMID:Stalled replication induces p53 accumulation through distinct mechanisms from DNA damage checkpoint pathways. 1648 26

The repair of DNA double-strand breaks (DSBs) is facilitated by the phosphorylation of H2AX, which organizes DNA damage signaling and chromatin remodeling complexes in the vicinity of the lesion. The disruption of DNA integrity induces an alteration of chromatin architecture that has been proposed to activate the DNA damage transducing kinase ataxia telangiectasia mutated. However, little is known about the physical properties of damaged chromatin. In this study, we use a photoactivatable version of GFP-tagged histone H2B to examine the mobility and structure of chromatin containing DSBs in living cells. We find that chromatin containing DSBs exhibits limited mobility but undergoes an energy-dependent local expansion immediately after DNA damage. The localized expansion observed in real time corresponds to a 30-40% reduction in the density of chromatin fibers in the vicinity of DSBs, as measured by energy-filtering transmission electron microscopy. The observed opening of chromatin occurs independently of H2AX and ATM. We propose that localized adenosine triphosphate-dependent decondensation of chromatin at DSBs establishes an accessible subnuclear environment that facilitates DNA damage signaling and repair.
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PMID:Changes in chromatin structure and mobility in living cells at sites of DNA double-strand breaks. 1652 Mar 85


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