601
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Huye LE, Purugganan MM, Jiang MM, Roth DB. Mutational analysis of all conserved basic amino acids in RAG-1 reveals catalytic, step arrest, and joining-deficient mutants in the V(D)J recombinase. Mol Cell Biol 2002; 22:3460-73. [PMID: 11971977 PMCID: PMC133788 DOI: 10.1128/mcb.22.10.3460-3473.2002] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although both RAG-1 and RAG-2 are required for all steps of V(D)J recombination, little is known about the specific contribution of either protein to these steps. RAG-1 contains three acidic active-site amino acids that are thought to coordinate catalytic metal ions. To search for additional catalytic amino acids and to better define the functional anatomy of RAG-1, we mutated all 86 conserved basic amino acids to alanine and evaluated the mutant proteins for DNA binding, nicking, hairpin formation, and joining. We found several amino acids outside of the canonical nonamer-binding domain that are critical for DNA binding, several step arrest mutants with defects in nicking or hairpin formation, and four RAG-1 mutants defective specifically for joining. Analysis of coding joints formed by some of these mutants revealed excessive deletions, frequent use of short sequence homologies, and unusually long palindromic junctional inserts, known as P nucleotides, that result from aberrant hairpin opening. These features characterize junctions found in scid mice, which are deficient for the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), suggesting that the RAG proteins and DNA-PKcs perform overlapping functions in coding joint formation. Interestingly, the amino acids that are altered in 12 of our mutants are also mutated in human inherited immunodeficiency syndromes. Our analysis of these mutants provides insights into the molecular mechanisms underlying these disorders.
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Affiliation(s)
- Leslie E Huye
- Department of Immunolog, Baylor College of Medicine, Houston, Texas 77030, USA
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602
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Candotti F, Notarangelo L, Visconti R, O'Shea J. Molecular aspects of primary immunodeficiencies: lessons from cytokine and other signaling pathways. J Clin Invest 2002; 109:1261-9. [PMID: 12021239 PMCID: PMC150986 DOI: 10.1172/jci15769] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Affiliation(s)
- Fabio Candotti
- Genetics and Molecular Biology Branch, National Human Genome Research Institute, NIH, Bethesda, Maryland 20892-1820, USA
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603
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Hacein-Bey-Abina S, Le Deist F, Carlier F, Bouneaud C, Hue C, De Villartay JP, Thrasher AJ, Wulffraat N, Sorensen R, Dupuis-Girod S, Fischer A, Davies EG, Kuis W, Leiva L, Cavazzana-Calvo M. Sustained correction of X-linked severe combined immunodeficiency by ex vivo gene therapy. N Engl J Med 2002; 346:1185-93. [PMID: 11961146 DOI: 10.1056/nejmoa012616] [Citation(s) in RCA: 893] [Impact Index Per Article: 40.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND X-linked severe combined immunodeficiency due to a mutation in the gene encoding the common gamma (gamma(c)) chain is a lethal condition that can be cured by allogeneic stem-cell transplantation. We investigated whether infusion of autologous hematopoietic stem cells that had been transduced in vitro with the gamma(c) gene can restore the immune system in patients with severe combined immunodeficiency. METHODS CD34+ bone marrow cells from five boys with X-linked severe combined immunodeficiency were transduced ex vivo with the use of a defective retroviral vector. Integration and expression of the gamma(c) transgene and development of lymphocyte subgroups and their functions were sequentially analyzed over a period of up to 2.5 years after gene transfer. RESULTS No adverse effects resulted from the procedure. Transduced T cells and natural killer cells appeared in the blood of four of the five patients within four months. The numbers and phenotypes of T cells, the repertoire of T-cell receptors, and the in vitro proliferative responses of T cells to several antigens after immunization were nearly normal up to two years after treatment. Thymopoiesis was documented by the presence of naive T cells and T-cell antigen-receptor episomes and the development of a normal-sized thymus gland. The frequency of transduced B cells was low, but serum immunoglobulin levels and antibody production after immunization were sufficient to avoid the need for intravenous immunoglobulin. Correction of the immunodeficiency eradicated established infections and allowed patients to have a normal life. CONCLUSIONS Ex vivo gene therapy with gamma(c) can safely correct the immune deficiency of patients with X-linked severe combined immunodeficiency.
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604
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605
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Abstract
When complexed with the catalytic subunit of DNA-dependent protein kinase (DNA-PK(cs)), the recently discovered dsDNA break repair protein named Artemis acquires the ability to open hairpin DNA molecules in vitro. Both genetic and biochemical data point toward a physiological role for this complex as the elusive hairpin-opening activity in V(D)J recombination.
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Affiliation(s)
- Mark S Schlissel
- Division of Immunology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
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606
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Brown ML, Franco D, Burkle A, Chang Y. Role of poly(ADP-ribosyl)ation in DNA-PKcs- independent V(D)J recombination. Proc Natl Acad Sci U S A 2002; 99:4532-7. [PMID: 11930007 PMCID: PMC123682 DOI: 10.1073/pnas.072495299] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2001] [Indexed: 11/18/2022] Open
Abstract
V(D)J recombination is critical to the generation of a functional immune system. Intrinsic to the assembly of antigen receptor genes is the formation of endogenous DNA double-strand breaks, which normally are excluded from the cellular surveillance machinery because of their sequestration in a synaptic complex and/or rapid resolution. In cells deficient in double-strand break repair, such recombination-induced breaks fail to be joined promptly and therefore are at risk of being recognized as DNA damage. Poly(ADP-ribose) polymerase-1 is an important factor in the maintenance of genomic integrity and is believed to play a central role in DNA repair. Here we provide visual evidence that in a recombination inducible severe combined immunodeficient cell line poly(ADP-ribose) formation occurs during the resolution stage of V(D)J recombination where nascent opened coding ends are generated. Poly(ADP-ribose) formation appears to facilitate coding end resolution. Furthermore, formation of Mre11 foci coincide with these areas of poly(ADP-ribosyl)ation. In contrast, such a response is not observed in wild-type cells possessing a functional catalytic subunit of DNA-dependent protein kinase (DNA-PK(cs)). Thus, V(D)J recombination invokes a DNA damage response in cells lacking DNA-PK(cs) activity, which in turn promotes DNA-PK(cs)-independent resolution of recombination intermediates.
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Affiliation(s)
- Matthew L Brown
- Department of Microbiology, Molecular and Cellular Biology Program, Arizona State University, Tempe, AZ 85287-2701, USA
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607
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Abstract
The RAG proteins were long thought to serve merely as a nuclease, initiating recombination by cleaving DNA. Recent work has shown, however, that these proteins are essential for many steps in the recombination pathway, such as opening hairpins and joining broken DNA ends, and that they can also act as a transposase, targeting distorted DNA structures such as hairpins.
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Affiliation(s)
- Vicky L Brandt
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
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608
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Neiditch MB, Lee GS, Huye LE, Brandt VL, Roth DB. The V(D)J recombinase efficiently cleaves and transposes signal joints. Mol Cell 2002; 9:871-8. [PMID: 11983177 DOI: 10.1016/s1097-2765(02)00494-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
V(D)J recombination generates two types of products: coding joints, which constitute the rearranged variable regions of antigen receptor genes, and signal joints, which often form on immunologically irrelevant, excised circular molecules that are lost during cell division. It has been widely believed that signal joints simply convert reactive broken DNA ends into safe, inert products. Yet two curious in vivo observations made us question this assumption: signal ends are far more abundant than coding ends, and signal joints form only after RAG expression is downregulated. In fact, we find that signal joints are not at all inert; they are cleaved quite efficiently in vivo and in vitro by a nick-nick mechanism and form an excellent substrate for RAG-mediated transposition in vitro, possibly explaining how genomic stability in lymphocytes may be compromised.
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Affiliation(s)
- Matthew B Neiditch
- Department of Immunology, Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
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609
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Abstract
V(D)J recombination is of fundamental importance to the generation of diverse antigen receptor repertoires. We review our current understanding of the V(D)J recombination reaction and how it is regulated during lymphocyte development. We also discuss how defects in the mechanism or regulation of V(D)J recombination can lead to human disease.
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Affiliation(s)
- Craig H Bassing
- Howard Hughes Medical Institute, The Children's Hospital, The Center for Blood Research, Boston, MA 02115, USA
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610
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Ma Y, Pannicke U, Schwarz K, Lieber MR. Hairpin opening and overhang processing by an Artemis/DNA-dependent protein kinase complex in nonhomologous end joining and V(D)J recombination. Cell 2002; 108:781-94. [PMID: 11955432 DOI: 10.1016/s0092-8674(02)00671-2] [Citation(s) in RCA: 768] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Mutations in the Artemis protein in humans result in hypersensitivity to DNA double-strand break-inducing agents and absence of B and T lymphocytes (radiosensitive severe combined immune deficiency [RS-SCID]). Here, we report that Artemis forms a complex with the 469 kDa DNA-dependent protein kinase (DNA-PKcs) in the absence of DNA. The purified Artemis protein alone possesses single-strand-specific 5' to 3' exonuclease activity. Upon complex formation, DNA-PKcs phosphorylates Artemis, and Artemis acquires endonucleolytic activity on 5' and 3' overhangs, as well as hairpins. Finally, the Artemis:DNA-PKcs complex can open hairpins generated by the RAG complex. Thus, DNA-PKcs regulates Artemis by both phosphorylation and complex formation to permit enzymatic activities that are critical for the hairpin-opening step of V(D)J recombination and for the 5' and 3' overhang processing in nonhomologous DNA end joining.
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Affiliation(s)
- Yunmei Ma
- Norris Comprehensive Cancer Center, Rm. 5428, Departments of Biochemistry & Molecular Biology, Pathology, Biological Sciences, and Molecular Microbiology & Immunology, 1441 Eastlake Avenue, Los Angeles, CA 90033, USA
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611
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Abstract
Studies of DNA repair and the maintenance of genomic integrity are essential to understanding the etiology and pathology of cancer. The availability of the complete genome sequence of Saccharomyces cerevissiae has greatly facilitated the discovery of new genes important for DNA repair.
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Affiliation(s)
- Ali Jazayeri
- Wellcome/Cancer Research UK Institute of Cancer and Developmental Biology and Department of Zoology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK.
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612
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Fischer A. Primary immunodeficiency diseases: natural mutant models for the study of the immune system. Scand J Immunol 2002; 55:238-41. [PMID: 11940230 DOI: 10.1046/j.1365-3083.2002.01056.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Primary immunodeficiency diseases represent many natural mutant models for the analysis of many aspects of immunology. Examples dealing with T- and B-cell receptors are herein discussed. They also represent privileged models in medicine, because well characterized monogenic inherited diseases can in some instances be viewed as good targets for gene therapy as shown here for severe combined immunodeficiency (SCID).
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Affiliation(s)
- A Fischer
- Unité d'Immunologie et d'Hématologie Pédiatriques/INSERM Unit 429, University Hôpital Necker-Enfants Malades, Paris, France
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613
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Tillman RE, Wooley AL, Hughes MM, Wehrly TD, Swat W, Sleckman BP. Restrictions limiting the generation of DNA double strand breaks during chromosomal V(D)J recombination. J Exp Med 2002; 195:309-16. [PMID: 11828005 PMCID: PMC2193590 DOI: 10.1084/jem.20011803] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Antigen receptor loci are composed of numerous variable (V), diversity (D), and joining (J) gene segments, each flanked by recombination signal sequences (RSSs). The V(D)J recombination reaction proceeds through RSS recognition and DNA cleavage steps making it possible for multiple DNA double strand breaks (DSBs) to be introduced at a single locus. Here we use ligation-mediated PCR to analyze DNA cleavage intermediates in thymocytes from mice with targeted RSS mutations at the endogenous TCRbeta locus. We show that DNA cleavage does not occur at individual RSSs but rather must be coordinated between RSS pairs flanking gene segments that ultimately form coding joins. Coordination of the DNA cleavage step occurs over great distances in the chromosome and favors intra- over interchromosomal recombination. Furthermore, through several restrictions imposed on the generation of both nonpaired and paired DNA DSBs, this requirement promotes antigen receptor gene integrity and genomic stability in developing lymphocytes undergoing V(D)J recombination.
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Affiliation(s)
- Robert E Tillman
- Washington University School of Medicine, Department of Pathology and Immunology, St. Louis, MO 63110, USA
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614
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Ding Q, Bramble L, Yuzbasiyan-Gurkan V, Bell T, Meek K. DNA-PKcs mutations in dogs and horses: allele frequency and association with neoplasia. Gene 2002; 283:263-9. [PMID: 11867233 DOI: 10.1016/s0378-1119(01)00880-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Previously, spontaneous genetic immunodeficiencies in mice, Arabian foals, and recently in Jack Russell terriers have been ascribed to defects in DNA-PKcs (catalytic subunit of the DNA dependent protein kinase) expression. In severe combined immunodeficiency (SCID) foals, a 5 bp deletion at codon 9480 results in a frameshift and a 967 amino acid deletion from the C terminus (including the entire PI3 kinase domain) and an unstable mutant protein. In SCID mice, a single base pair mutation results in a premature stop codon and deletion of 83 amino acids; as in SCID foals, the mutant protein is unstable. Here, we define the mutation within the canine DNA-PKcs gene that results in SCID. In this case, a point mutation results in a stop codon at nucleotide 10,828 and premature termination at a position 517 amino acids before the normal C terminus resulting in a functionally null allele. Thus, this is the third documentation of a spontaneous germline mutation in the C terminus of DNA-PKcs. Emerging data implicate DNA repair factors as potential tumor suppressors. Here, we have ascertained the carrier frequency of the defective DNA-PKcs genes in Arabian horses and in Jack Russell terriers. Our data indicate (in good agreement with a previous report) that the carrier frequency of the equine SCID allele is approximately 8%; in contrast, the carrier frequency of the canine SCID allele is less than 1.1%. We also assessed the frequency of the equine SCID allele in a series of 295 tumors from Arabian horses. We find a statistically significant correlation between the development of a virally induced tumor (sarcoid) and heterozygosity for the equine SCID allele. These data provide further support for an emerging consensus: that DNA-PK may normally act as a tumor suppressor through its caretaker role in maintaining chromosomal stability.
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Affiliation(s)
- Qi Ding
- College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
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615
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Jeggo PA, Concannon P. Immune diversity and genomic stability: opposite goals but similar paths. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2001; 65:88-96. [PMID: 11809363 DOI: 10.1016/s1011-1344(01)00243-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
DNA damage response mechanisms serve to protect cells from exogenous and endogenous DNA damaging agents with the aim of maintaining genomic stability. In contrast, the generation of an efficient immune response requires the creation of a repertoire of distinct immunoglobulin and T cell receptor genes able to recognise the huge array of antigens that may be encountered in a lifetime. Surprisingly, cells have exploited the same mechanisms used to maintain genomic integrity to create genetic diversity during immune development. Here, we review the damage response mechanisms operating on DNA double strand breaks and their function during development of the immune response. We discuss disorders that are associated with immunodeficiency and defective responses to the presence of DNA double strand breaks.
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Affiliation(s)
- P A Jeggo
- Genome Damage and Stability Centre, University of Sussex, Brighton, East Sussex, UK.
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616
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Abstract
In humans several abnormalities can occur during terminal B cell differentiation, leading to primary humoral immunodeficiencies. A recent study provided evidence of a qualitative defect of the affinity antibody maturation in some patients affected with common variable immunodeficiency syndrome, the molecular basis of which remains unknown. Several genetic defects in class switch recombination leading to a hyper-IgM syndrome have recently been delineated. Besides the well-known role of CD40-CD40 ligand interaction, they definitively demonstrate the requirement of CD40-mediated nuclear factor kappa B activation and the essential role of a newly described molecule, the activation-induced cytidine deaminase, in B cell terminal differentiation.
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Affiliation(s)
- A Durandy
- Inserm U429, Hôpital Necker-Enfants Malades, Paris, France.
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617
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Sharpless NE, Ferguson DO, O'Hagan RC, Castrillon DH, Lee C, Farazi PA, Alson S, Fleming J, Morton CC, Frank K, Chin L, Alt FW, DePinho RA. Impaired nonhomologous end-joining provokes soft tissue sarcomas harboring chromosomal translocations, amplifications, and deletions. Mol Cell 2001; 8:1187-96. [PMID: 11779495 DOI: 10.1016/s1097-2765(01)00425-7] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although nonhomologous end-joining (NHEJ) deficiency has been shown to accelerate lymphoma formation in mice, its role in suppressing tumors in cells that do not undergo V(D)J recombination is unclear. Utilizing a tumor-prone mouse strain (ink4a/arf(-/-)), we examined the impact of haploinsufficiency of a NHEJ component, DNA ligase IV (Lig4), on murine tumorigenesis. We demonstrate that lig4 heterozygosity promotes the development of soft-tissue sarcomas that possess clonal amplifications, deletions, and translocations. That these genomic alterations are relevant in tumorigenesis is supported by the finding of frequent mdm2 amplification, a known oncogene in human sarcoma. Together, these findings support the view that loss of a single lig4 allele results in NHEJ activity being sufficiently reduced to engender chromosomal aberrations that drive non-lymphoid tumorigenesis.
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Affiliation(s)
- N E Sharpless
- Department of Adult Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
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618
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Abstract
Mutations in recombination activating genes cause a spectrum of severe immunodeficiencies ranging from T-B severe combined immunodeficiency to Omenn syndrome (a particular type of severe combined immunodeficiency presenting a T+ B- profile). Although environmental factors and genetic background could also contribute to the genesis of this pathological condition, a residual recombination activating gene activity allowing for a few recombinational events to occur, is the first determinant of this variability in the clinical picture.
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Affiliation(s)
- A Villa
- Istituto di Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate, Italy.
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619
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Abstract
The recently determined crystal structure of the Ku heterodimer, in both DNA-bound and unbound forms, has shed new light on the mechanism by which this protein fulfills its key role in the repair of DNA double-strand breaks.
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Affiliation(s)
- A J Doherty
- Cambridge Institute for Medical Research, Department of Haematology, University of Cambridge, Hills Road, Cambridge CB2 2XY, UK.
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620
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Pierce AJ, Stark JM, Araujo FD, Moynahan ME, Berwick M, Jasin M. Double-strand breaks and tumorigenesis. Trends Cell Biol 2001. [DOI: 10.1016/s0962-8924(01)82296-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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621
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Pierce AJ, Stark JM, Araujo FD, Moynahan ME, Berwick M, Jasin M. Double-strand breaks and tumorigenesis. Trends Cell Biol 2001; 11:S52-9. [PMID: 11684443 DOI: 10.1016/s0962-8924(01)02149-3] [Citation(s) in RCA: 158] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The establishment of connections between biochemical defects and clinical disease is a major goal of modern molecular genetics. In this review, we examine the current literature that relates defects in the two major DNA double-strand-break repair pathways--homologous recombination and nonhomologous end-joining--with the development of human tumors. Although definitive proof has yet to be obtained, the current literature is highly suggestive of such a link.
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Affiliation(s)
- A J Pierce
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA
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622
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Abstract
Recent clinical trials in patients with a severe combined immunodeficiency disease demonstrate that gene therapy is a powerful tool in the treatment of genetic blood defects. Recent identification of the genes involved in the pathogenesis of inherited lymphohemopoietic disorders led to animal models of gene transfer. Extensive preclinical studies have overcome some of the obstacles involved in the transduction of hemopoietic cells. These promising results led to the approval of several clinical trials that are currently underway. This review focuses on the clinical outcome in patients with genetic blood defects treated by gene transfer and examines the progress achieved to date and the problems that have been encountered. Despite the obstacles, improved clinical results for several of these diseases are expected within the next 5 years.
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Affiliation(s)
- M Cavazzana-Calvo
- Laboratoire de Thérapie Cellulaire et Génique AP-HP and INSERM U429, Hôpital Necker-Enfants Malades, Paris, France.
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623
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Arbuckle JL, Fauss LA, Simpson R, Ptaszek LM, Rodgers KK. Identification of two topologically independent domains in RAG1 and their role in macromolecular interactions relevant to V(D)J recombination. J Biol Chem 2001; 276:37093-101. [PMID: 11479318 DOI: 10.1074/jbc.m105988200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
V(D)J recombination is instigated by the recombination-activating proteins RAG1 and RAG2, which catalyze site-specific DNA cleavage at the border of the recombination signal sequence (RSS). Although both proteins are required for activity, core RAG1 (the catalytically active region containing residues 384-1008 of 1040) alone displays binding specificity for the conserved heptamer and nonamer sequences of the RSS. The nonamer-binding region lies near the N terminus of core RAG1, whereas the heptamer-binding region has not been identified. Here, potential domains within core RAG1 were identified using limited proteolysis studies. An iterative procedure of DNA cloning, protein expression, and characterization revealed the presence of two topologically independent domains within core RAG1, referred to as the central domain (residues 528-760) and the C-terminal domain (residues 761-980). The domains do not include the nonamer-binding region but rather largely span the remaining relatively uncharacterized region of core RAG1. Characterization of macromolecular interactions revealed that the central domain bound to the RSS with specificity for the heptamer and contained the predominant binding site for RAG2. The C-terminal domain bound DNA cooperatively but did not show specificity for either conserved RSS element. This domain was also found to self-associate, implicating it as a dimerization domain within RAG1.
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Affiliation(s)
- J L Arbuckle
- Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190, USA
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624
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625
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Ferguson DO, Alt FW. DNA double strand break repair and chromosomal translocation: lessons from animal models. Oncogene 2001; 20:5572-9. [PMID: 11607810 DOI: 10.1038/sj.onc.1204767] [Citation(s) in RCA: 252] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The maintenance of genomic stability is one of the most important defenses against neoplastic transformation. This objective must be accomplished despite a constant barrage of spontaneous DNA double strand breaks. These dangerous lesions are corrected by two primary pathways of double strand break repair; non homologous end joining and homologous recombination. Recent studies employing mouse models have shown that absence of either pathway leads to genomic instability, including potentially oncogenic translocations. Because translocations involve the union of different chromosomes, cellular machinery must exist that creates these structures in the context of unrepaired double strand breaks. Evidence is mounting that the pathways of double strand break repair that are so important for survival may themselves be the culprits that generate potentially fatal translocations. Evidence and models for the dual roles of double strand break repair in both preventing, and generating, oncogenic karyotypic changes are discussed.
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Affiliation(s)
- D O Ferguson
- The Center for Blood Research, Harvard Medical School, Boston, Massachusetts, MA 02115, USA
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626
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Abstract
DNA interstrand cross-links (ICLs) are very toxic to dividing cells, because they induce mutations, chromosomal rearrangements and cell death. Inducers of ICLs are important drugs in cancer treatment. We discuss the main properties of several classes of ICL agents and the types of damage they induce. The current insights in ICL repair in bacteria, yeast and mammalian cells are reviewed. An intriguing aspect of ICLs is that a number of multi-step DNA repair pathways including nucleotide excision repair, homologous recombination and post-replication/translesion repair all impinge on their repair. Furthermore, the breast cancer-associated proteins Brca1 and Brca2, the Fanconi anemia-associated FANC proteins, and cell cycle checkpoint proteins are involved in regulating the cellular response to ICLs. We depict several models that describe possible pathways for the repair or replicational bypass of ICLs.
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Affiliation(s)
- M L Dronkert
- Department of Cell Biology and Genetics, Erasmus University Rotterdam, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands
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627
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Soubeyrand S, Torrance H, Giffin W, Gong W, Schild-Poulter C, Haché RJ. Activation and autoregulation of DNA-PK from structured single-stranded DNA and coding end hairpins. Proc Natl Acad Sci U S A 2001; 98:9605-10. [PMID: 11481441 PMCID: PMC55499 DOI: 10.1073/pnas.171211398] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
DNA-dependent protein kinase (DNA-PK) acts through an essential relationship with DNA to participate in the regulation of multiple cellular processes. Yet the role of DNA as a cofactor in kinase activity remains to be completely elucidated. For example, although DNA-PK activity appears to be required for the resolution of hairpin coding ends in variable diversity joining recombination, kinase activity remains to be demonstrated from hairpin ends or other DNA structures. In the present study we report that DNA-PK is strongly activated from hairpin ends and structured single-stranded DNA, but that the phosphorylation of many heterologous substrates is blocked efficiently by inactivation of the kinase through autophosphorylation. However, substrates that bound efficiently to single-stranded DNA such as p53 and replication protein A were efficiently phosphorylated by DNA-PK from structured DNA. DNA-PK also was found to be active toward heterologous substrates from hairpin ends on double-stranded DNA under conditions where autophosphorylation was minimized. These results suggest that the role of DNA-PK in resolving coding end hairpins is likely to be enzymatic rather than structural, expand understanding of how DNA-PK binding to structured DNA relates to enzyme activity, and suggest a mechanism for autoregulatory control of its kinase activity in the cell.
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Affiliation(s)
- S Soubeyrand
- Department of Medicine, University of Ottawa, Ottawa Health Research Institute, ON, Canada
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628
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Daiyasu H, Osaka K, Ishino Y, Toh H. Expansion of the zinc metallo-hydrolase family of the beta-lactamase fold. FEBS Lett 2001; 503:1-6. [PMID: 11513844 DOI: 10.1016/s0014-5793(01)02686-2] [Citation(s) in RCA: 258] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recently, the zinc metallo-hydrolase family of the beta-lactamase fold has grown quite rapidly, accompanied by the accumulation of sequence and structure data. The variety of the biological functions of the family is higher than expected. In addition, the members often have mosaic structures with additional domains. The family includes class B beta-lactamase, glyoxalase II, arylsulfatase, flavoprotein, cyclase/dehydrase, an mRNA 3'-processing protein, a DNA cross-link repair enzyme, a DNA uptake-related protein, an alkylphosphonate uptake-related protein, CMP-N-acetylneuraminate hydroxylase, the romA gene product, alkylsulfatase, and insecticide hydrolases. In this minireview, the functional and structural varieties of the growing protein family are described.
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Affiliation(s)
- H Daiyasu
- Department of Bioinformatics, Biomolecular Engineering Research Institute, Osaka, Japan
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629
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Dagher MC. Artemis watches over DNA. Trends Biochem Sci 2001. [DOI: 10.1016/s0968-0004(01)01901-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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630
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Affiliation(s)
- D E Barnes
- Mutagenesis Laboratory, ICRF Clare Hall Laboratories, South Mimms, EN6 3LD, Hertfordshire, UK
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631
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Abstract
Primary immunodeficiency diseases represent a vast array of inherited disorders of the immune system. Major advances in the understanding of genetic basis and molecular mechanisms have occurred within the past 10 years, as a result of the tools of modern genetics. About three quarters of 100 primary immunodeficiency diseases can now be reliably diagnosed with molecular probes. In many cases, gene identification has enabled significant insight into the physiopathology of the related conditions. Therapeutic progress based on protein engineering and possibly gene therapy will also ensue.
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Affiliation(s)
- A Fischer
- INSERM U429, Hôpital Necker, 149 Rue de Sévres, 75015, Paris, France.
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