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)

ATM, the gene mutated in the human immunodeficiency disorder ataxia-telangiectasia (A-T), plays a central role in recognizing ionizing radiation damage in DNA and in controlling several cell cycle checkpoints. We describe here a murine model in which a nine-nucleotide in-frame deletion has been introduced into the Atm gene by homologous recombination followed by removal of the selectable marker cassette by Cre-loxP site-specific, recombination-mediated excision. This mouse, Atm-DeltaSRI, was designed as a model of one of the most common deletion mutations (7636del9) found in A-T patients. The murine Atm deletion results in the loss of three amino acid residues (SRI; 2556-2558) but produces near full-length detectable Atm protein that lacks protein kinase activity. Radiosensitivity was observed in Atm-DeltaSRI mice, whereas the immunological profile of these mice showed greater heterogeneity of T-cell subsets than observed in Atm(-/-) mice. The life span of Atm-DeltaSRI mice was significantly longer than that of Atm(-/-) mice when maintained under nonspecific pathogen-free conditions. This can be accounted for by a lower incidence of thymic lymphomas in Atm-DeltaSRI mice up to 40 weeks, after which time the animals died of other causes. The thymic lymphomas in Atm-DeltaSRI mice were characterized by extensive apoptosis, which appears to be attributable to an increased number of cells expressing Fas ligand. A variety of other tumors including B-cell lymphomas, sarcomas, and carcinomas not seen in Atm(-/-) mice were observed in older Atm-DeltaSRI animals. Thus, expression of mutant protein in Atm-DeltaSRI knock-in mice gives rise to a discernibly different phenotype to Atm(-/-) mice, which may account for the heterogeneity seen in A-T patients with different mutations.
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PMID:Atm knock-in mice harboring an in-frame deletion corresponding to the human ATM 7636del9 common mutation exhibit a variant phenotype. 1138 91

The B-cell lymphoproliferative malignancies B-cell chronic lymphocytic leukemia (B-CLL) and mantle cell lymphoma (MCL) share characteristics, including overlapping chromosomal aberrations with deletions on chromosome bands 13q14, 11q23, 17p13, and 6q21 and gains on chromosome bands 3q26, 12q13, and 8q24. To elucidate the biochemical processes involved in the pathogenesis of B-CLL and MCL, we analyzed the expression level of a set of genes that play central roles in apoptotic or cell proliferation pathways and of candidate genes from frequently altered genomic regions, namely ATM, BAX, BCL2, CCND1, CCND3, CDK2, CDK4, CDKN1A, CDKN1B, E2F1, ETV5, MYC, RB1, SELL, TFDP2, TNFSF10, and TP53. Performing real-time quantitative reverse transcription polymerase chain reaction in a panel of patients with MCL and B-CLL and control samples, significant overexpression and underexpression was observed for most of these genes. Statistical analysis of the expression data revealed the combination of CCND1 and CDK4 as the best classifier concerning separation of both lymphoma types. Overexpression in these malignancies suggests ETV5 as a new candidate for a pathogenic factor in B-cell lymphomas. Characteristic deregulation of multiple genes analyzed in this study could be combined in a comprehensive picture of 2 distinctive pathomechanisms in B-CLL and MCL. In B-CLL, the expression parameters are in strong favor of protection of the malignant cells from apoptosis but did not provide evidence for promoting cell cycle. In contrast, in MCL the impairment of apoptosis induction seems to play a minor role, whereas most expression data indicate an enhancement of cell proliferation.
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PMID:Evidence for distinct pathomechanisms in B-cell chronic lymphocytic leukemia and mantle cell lymphoma by quantitative expression analysis of cell cycle and apoptosis-associated genes. 1203 88

Loss of function of the ataxia-telangiectasia mutated (ATM) gene, located on human chromosome 11q22-23, is the cause of ataxia-telangiectasia (A-T), which is associated with an extremely high risk for lymphoma. Abnormalities in 11q22-23, including deletions and mutations of the ATM gene, have been reported in T-cell prolymphocytic leukemias, B-CLL and in mantle cell lymphoma. In a survey of gene expression in follicle center lymphomas (FCL) and diffuse large B-cell lymphomas (DLBCL), almost all FCL expressed significant levels of ATM and the majority of DLBCL expressed low levels of ATM. This finding raised the possibility that the transformation of some FCL to DLBCL might be associated with inactivation of the ATM gene. Therefore, we analyzed biopsy specimens of 17 patients with FCL obtained at the time of diagnosis, four subsequent biopsies obtained at the time of FCL relapse and seven subsequent biopsies at the time of transformation to DLBCL. A comprehensive analysis of the ATM gene was performed by denaturing high performance liquid chromatography and sequencing. The analysis covered all of the 66 exons including the 9168 base pairs of ATM coding sequence as well as 16,676 base pairs of non-coding sequence. Twenty-eight known polymorphisms and rare sequence variants were observed, but no classic A-T mutations were detected. In 11 tumors, both tumor B-cells and normal T-cells were sorted for separate examination, and in each case, polymorphisms and rare variants were present in both tumor and normal cells. No new ATM gene mutations were associated with transformation from FCL to DLBCL. Thus, ATM gene mutations do not play a pivotal role either in the pathogenesis of FCL or in its transformation to DLBCL.
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PMID:Mutation of the ATM gene is not involved in the pathogenesis of either follicle center lymphoma or its transformation to higher-grade lymphoma. 1214 90

The ATM serine-threonine kinase plays a central role in the cellular response to DNA damage. Germ-line mutations in the ATM gene cause ataxia-telangiectasia (A-T), a multisystem disorder associated with predisposition to lymphoma and acute leukemia. Moreover, somatic ATM mutations have been identified in T-cell prolymphocytic leukemia, mantle cell lymphoma, and B-cell chronic lymphocytic leukemia. In this study, the entire ATM coding sequence was examined in genomic DNA from 120 lymphoid neoplasms. Novel mutations and mutations implicated in cancer and/or A-T were found in 9 of 45 diffuse large B-cell lymphomas (DLBCLs), 2 of 24 follicular lymphomas, and 1 of 27 adult acute lymphoblastic leukemias, whereas no such mutations were detected among 24 peripheral T-cell lymphomas. The mutational spectrum consisted of 2 nonsense mutations, 1 mutation affecting RNA splicing, and 10 missense variants. Most of these mutations were associated with loss or mutation of the paired ATM allele, consistent with biallelic inactivation of ATM. Of the 9 DLBCLs with ATM mutations, 7 also carried TP53 mutations and/or deletions of the INK4a/ARF locus (P =.003). The ATM 735C>T substitution previously considered a rare normal variant was found to be 5.6 times more frequent in individuals with DLBCL than in random individuals (P =.026), suggesting that it may predispose to B-cell lymphoma. Our data suggest that ATM mutations contribute to the development of DLBCL, and that ATM and the ARF-p53 tumor suppressor pathway may cooperate in the pathogenesis of this malignancy.
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PMID:ATM mutations are associated with inactivation of the ARF-TP53 tumor suppressor pathway in diffuse large B-cell lymphoma. 1214 28

CD5(+) diffuse large B-cell lymphomas (DLBLs) have recently been described as a particular subgroup of DLBLs. Classical banding and interphase cytogenetic analyses targeting ATM, TP53, and P16(INK4a) genes and the D13S25 locus from 13 CD5(+) DLBLs were compared with 55 CD5(-) DLBLs. Additionally, analysis of somatic mutations of the immunoglobulin heavy chain variable region (IgVH) genes were performed in CD5(+) DLBLs. CD5(+) DLBLs were somatically mutated (7 of 8 cases) and were negative for t(11;14)(q13;q32) and t(14;18)(q32;q21), whereas t(3;14)(q27;q32) was found in only one tumor. Trisomy 3 and gains on chromosomes 16/16p and 18/18q were significantly overrepresented in CD5(+) DLBLs. No ATM deletions were detected. The prevalence of deletions at the D13S25 locus was significantly higher in CD5(+) DLBLs (4 of 12 [33%]) compared with CD5(-) DLBLs (4 of 42 [10%]), as were p16(INK4a) deletions (33% versus 8%). On the basis of these findings, CD5(+) DLBLs are likely to arise from the same progenitor cell as the mutated variant of CD5(+) lymphocytic lymphoma/B-cell chronic lymphocytic leukemia (B-CLL).
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PMID:Genetic analysis of de novo CD5+ diffuse large B-cell lymphomas suggests an origin from a somatically mutated CD5+ progenitor B cell. 1239 24

CHK1: gene encodes for a serine/threonine kinase involved in the regulation of cell cycle progression and DNA damage checkpoints. To determine the role of CHK1 in the pathogenesis of lymphoid neoplasms and its relationship to other DNA damage response genes, we have analyzed the gene status, protein, and mRNA expression in a series of tumors and nonneoplastic lymphoid tissues. CHK1 protein and mRNA expression levels were very low in both reactive tissues and resting lymphoid cells, whereas tumor samples showed a variable pattern of expression related to their proliferative activity. However, seven aggressive tumors showed a dissociate pattern of extremely low or negative protein expression in spite of a high proliferative activity. Four of these tumors were diffuse large B-cell lymphomas (DLCLs) with concordant reduced levels of mRNA, whereas one blastoid mantle cell lymphoma (B-MCL) and two DLCLs had relatively normal levels of mRNA. No gene mutations, deletions, or hypermethylation of the promoter region were detected in any of these cases. In all these tumors ATM, CHK2, and p53 genes were wild type. These findings suggest that CHK1 inactivation in NHLs occurs by loss of protein expression in a subset of aggressive variants alternatively to ATM, CHK2, and p53 alterations.
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PMID:Checkpoint kinase 1 (CHK1) protein and mRNA expression is downregulated in aggressive variants of human lymphoid neoplasms. 1552 25

Hodgkin's lymphoma (HL) is a lymphoid malignancy characterized by the presence of rare neoplastic cells, Hodgkin and Reed-Sternberg (HRS) cells, scattered among a predominant population of inflammatory cells. On the basis of previously reported cytogenetic analyses, the ATM (ataxia-telangiectasia mutated) gene at 11q22-23 has been implicated in the etiology of HL. We therefore developed a single-cell PCR approach to detect ATM loss of heterozygosity (LOH) in HRS cells. Three microsatellites were investigated; 1 localized inside the ATM gene and the remaining 2 in close proximity. In 2 of the 15 lymph node samples, an allelic loss of the ATM gene locus was detected. ATM protein expression was examined in 8 cases (including 1 of the 2 cases with LOH) by immunohistochemistry. In the case associated with an allelic loss, the ATM protein was absent in the HRS cells, whereas in the 7 remaining cases, without detectable LOH at the ATM locus, nuclear ATM expression was observed. In the 2 HL cases with LOH, the ATM gene was sequenced following whole genome amplification of DNA isolated from microdissected HRS cells. In 1 of these 2 cases, a splice site mutation in the second ATM allele was found. This mutation could generate a premature termination codon leading to a marked instability and a rapid degradation of the resulting ATM mRNA transcripts. This latter event could explain the loss of the expression of the ATM protein in HRS cells as detected by immunohistochemistry in this particular case. As previously reported in some B-cell lymphomas, our results suggest that ATM genetic anomalies could play a role in the pathogenesis of a subset of HL cases.
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PMID:Single-cell analysis of loss of heterozygosity at the ATM gene locus in Hodgkin and Reed-Sternberg cells of Hodgkin's lymphoma: ATM loss of heterozygosity is a rare event. 1564 96

To identify recurrent genomic changes in mantle cell lymphoma (MCL), we used high-resolution comparative genomic hybridization (CGH) to bacterial artificial chromosome (BAC) microarrays in 68 patients and 9 MCL-derived cell lines. Array CGH defined an MCL genomic signature distinct from other B-cell lymphomas, including deletions of 1p21 and 11q22.3-ATM gene with coincident 10p12-BMI1 gene amplification and 10p14 deletion, along with a previously unidentified loss within 9q21-q22. Specific genomic alterations were associated with different subgroups of disease. Notably, 11 patients with leukemic MCL showed a different genomic profile than nodal cases, including 8p21.3 deletion at tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor gene cluster (55% versus 19%; P = .01) and gain of 8q24.1 at MYC locus (46% versus 14%; P = .015). Additionally, leukemic MCL exhibited frequent IGVH mutation (64% versus 21%; P = .009) with preferential VH4-39 use (36% versus 4%; P = .005) and followed a more indolent clinical course. Blastoid variants, increased number of genomic gains, and deletions of P16/INK4a and TP53 genes correlated with poorer outcomes, while 1p21 loss was associated with prolonged survival (P = .02). In multivariate analysis, deletion of 9q21-q22 was the strongest predictor for inferior survival (hazard ratio [HR], 6; confidence interval [CI], 2.3 to 15.7). Our study highlights the genomic profile as a predictor for clinical outcome and suggests that "genome scanning" of chromosomes 1p21, 9q21-q22, 9p21.3-P16/INK4a, and 17p13.1-TP53 may be clinically useful in MCL.
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PMID:Mantle-cell lymphoma genotypes identified with CGH to BAC microarrays define a leukemic subgroup of disease and predict patient outcome. 1571 13

Hepatitis C virus (HCV) infection is frequently associated with the development of hepatocellular carcinomas and non-Hodgkin's B-cell lymphomas. Nonstructural protein 3 (NS3) of HCV possesses serine protease, nucleoside triphosphatase, and helicase activities, while NS4A functions as a cofactor for the NS3 serine protease. Here, we show that HCV NS3/4A interacts with the ATM (ataxia-telangiectasia mutated), a cellular protein essential for cellular response to irradiation. The expression of NS3/4A caused cytoplasmic translocation of either endogenous or exogenous ATM and delayed dephosphorylation of the phosphorylated ATM and gamma-H2AX following ionizing irradiation. As a result, the irradiation-induced gamma-H2AX foci persisted longer in the NS3/4A-expressing cells. Furthermore, these cells showed increased comet tail moment in single-cell electrophoresis assay, indicating increased double-strand DNA breaks. The cells harboring an HCV replicon also exhibited cytoplasmic localization of ATM and increased sensitivity to irradiation. These results demonstrate that NS3/4A impairs the efficiency of DNA repair by interacting with ATM and renders the cells more sensitive to DNA damage. This effect may contribute to HCV oncogenesis.
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PMID:Hepatitis C virus NS3/4A protein interacts with ATM, impairs DNA repair and enhances sensitivity to ionizing radiation. 1793 78

Chromosome translocations between Ig (Ig) and non-Ig genes are frequently associated with B-cell lymphomas in humans and mice. The best characterized of these is c-myc/IgH translocation, which is associated with Burkitt's lymphoma. These translocations are caused by activation-induced cytidine deaminase (AID), which produces double-strand DNA breaks in both genes. c-myc/IgH translocations are rare events, in part because ATM, p53, and p19 actively suppress them. To further define the mechanism of protection against the accumulation of cells that bear c-myc/IgH translocation, we assayed B cells from mice that carry mutations in cell-cycle and apoptosis regulator proteins that act downstream of p53. We find that PUMA, Bim, and PKCdelta are required for protection against c-myc/IgH translocation, whereas Bcl-XL and BAFF enhance c-myc/IgH translocation. Whether these effects are general or specific to c-myc/IgH translocation and whether AID produces dsDNA breaks in genes other than c-myc and Ig is not known. To examine these questions, we developed an assay for translocation between IgH and Igbeta, both of which are somatically mutated by AID. Igbeta/IgH, like c-myc/IgH translocations, are AID-dependent, and AID is responsible for lesions on IgH and the non-IgH translocation partners. However, ATM, p53, and p19 do not protect against Igbeta/IgH translocations. Instead, B cells are protected against Igbeta/IgH translocations by a BAFF- and PKCdelta-dependent pathway. We conclude that AID-induced double-strand breaks in non-Ig genes other than c-myc lead to their translocation, and that at least two nonoverlapping pathways protect against translocations in primary B cells.
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PMID:Role of the translocation partner in protection against AID-dependent chromosomal translocations. 1996 90


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