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Durkin SS, Guo X, Fryrear KA, Mihaylova VT, Gupta SK, Belgnaoui SM, Haoudi A, Kupfer GM, Semmes OJ. HTLV-1 Tax oncoprotein subverts the cellular DNA damage response via binding to DNA-dependent protein kinase. J Biol Chem 2008; 283:36311-20. [PMID: 18957425 PMCID: PMC2605996 DOI: 10.1074/jbc.m804931200] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Human T-cell leukemia virus type-1 is the causative agent for adult T-cell leukemia. Previous research has established that the viral oncoprotein Tax mediates the transformation process by impairing cell cycle control and cellular response to DNA damage. We showed previously that Tax sequesters huChk2 within chromatin and impairs the response to ionizing radiation. Here we demonstrate that DNA-dependent protein kinase (DNA-PK) is a member of the Tax.Chk2 nuclear complex. The catalytic subunit, DNA-PKcs, and the regulatory subunit, Ku70, were present. Tax-containing nuclear extracts showed increased DNA-PK activity, and specific inhibition of DNA-PK prevented Tax-induced activation of Chk2 kinase activity. Expression of Tax induced foci formation and phosphorylation of H2AX. However, Tax-induced constitutive signaling of the DNA-PK pathway impaired cellular response to new damage, as reflected in suppression of ionizing radiation-induced DNA-PK phosphorylation and gammaH2AX stabilization. Tax co-localized with phospho-DNA-PK into nuclear speckles and a nuclear excluded Tax mutant sequestered endogenous phospho-DNA-PK into the cytoplasm, suggesting that Tax interaction with DNA-PK is an initiating event. We also describe a novel interaction between DNA-PK and Chk2 that requires Tax. We propose that Tax binds to and stabilizes a protein complex with DNA-PK and Chk2, resulting in a saturation of DNA-PK-mediated damage repair response.
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Affiliation(s)
- Sarah S Durkin
- Department of Microbiology and Molecular Cell Biology, Center for Biomedical Proteomics, Eastern Virginia Medical School, Norfolk, Virginia 23507, USA
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Haider S, Hayakawa K, Itoyama T, Sadamori N, Kurosawa N, Isobe M. TCR variable gene involvement in chromosome inversion between 14q11 and 14q24 in adult T-cell leukemia. J Hum Genet 2006; 51:326-334. [PMID: 16520872 DOI: 10.1007/s10038-006-0364-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2005] [Accepted: 12/18/2005] [Indexed: 10/24/2022]
Abstract
Chromosomal translocations in T-cell malignancies frequently involve the T-cell receptor (TCR)alpha/delta locus at chromosome 14q11. Although 14q11 abnormalities are found in about 10% of adult T-cell leukemia (ATL) cases, until now there has been no direct evidence showing involvement of the TCR locus in ATL-a malignancy closely associated with HTLV-1 infection. The breakpoints of T-cell malignancies most commonly occur within the Jalpha or Jdelta region of the TCR locus. In ATL, however, despite extensive searching no breakpoint has yet been found in that region. Using fluorescence in situ hybridization with a panel of cosmid and bacterial artificial chromosome probes derived from chromosome 14, including the variable region of the TCRalpha locus, comprehensive analysis of an ATL patient carrying inv(14)(q11q32) revealed that the TCR locus was indeed involved in this inversion. Molecular cloning of the breakpoint revealed the juxtaposition of TCR Valpha to the 14q24 region as a result of two consecutive inversions: inv(14)(q11q32) and inv(14)(q11q24). We also found a gene near the breakpoint at the 14q24 region that is downregulated in this ATL patient and is assigned in the database as a pseudogene of ADAM21 (a disintegrin and metalloproteinase domain 21). Our expression analysis, however, showed that this pseudogene was actually expressed and was capable of encoding a protein similar to ADAM21; thus we have named this gene ADAM21-like (ADAM21-L).
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MESH Headings
- ADAM Proteins/metabolism
- ADAM12 Protein
- Adult
- Animals
- Base Sequence
- Blotting, Southern
- COS Cells
- Cells, Cultured
- Chlorocebus aethiops
- Chromosome Inversion
- Chromosomes, Human, Pair 14
- DNA/genetics
- Electrophoresis, Polyacrylamide Gel
- Gene Expression Regulation, Leukemic
- Genes, T-Cell Receptor
- Humans
- In Situ Hybridization, Fluorescence
- Karyotyping
- Leukemia-Lymphoma, Adult T-Cell/diagnosis
- Leukemia-Lymphoma, Adult T-Cell/genetics
- Leukocytes, Mononuclear/cytology
- Membrane Proteins/metabolism
- Models, Genetic
- Molecular Sequence Data
- Restriction Mapping
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Analysis, DNA
- Transfection
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Affiliation(s)
- Shawkat Haider
- Laboratory of Molecular and Cellular Biology, Department of Materials and Biosystem Engineering, Faculty of Engineering, Toyama University, 3190 Gofuku, Toyama, 930-8555, Japan
| | - Kousuke Hayakawa
- Laboratory of Molecular and Cellular Biology, Department of Materials and Biosystem Engineering, Faculty of Engineering, Toyama University, 3190 Gofuku, Toyama, 930-8555, Japan
| | - Takahiro Itoyama
- Laboratory of Molecular and Cellular Biology, Department of Materials and Biosystem Engineering, Faculty of Engineering, Toyama University, 3190 Gofuku, Toyama, 930-8555, Japan
| | - Naoki Sadamori
- Department of Nursing, Siebold University of Nagasaki, Nagasaki, 851-2195, Japan
| | - Nobuyuki Kurosawa
- Laboratory of Molecular and Cellular Biology, Department of Materials and Biosystem Engineering, Faculty of Engineering, Toyama University, 3190 Gofuku, Toyama, 930-8555, Japan
| | - Masaharu Isobe
- Laboratory of Molecular and Cellular Biology, Department of Materials and Biosystem Engineering, Faculty of Engineering, Toyama University, 3190 Gofuku, Toyama, 930-8555, Japan.
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