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  • 1
    In: BMC Genomics, Springer Science and Business Media LLC, Vol. 20, No. 1 ( 2019-12)
    Abstract: APOBEC1 (A1) enzymes are cytidine deaminases involved in RNA editing. In addition to this activity, a few A1 enzymes have been shown to be active on single stranded DNA. As two human ssDNA cytidine deaminases APOBEC3A (A3A), APOBEC3B (A3B) and related enzymes across the spectrum of placental mammals have been shown to introduce somatic mutations into nuclear DNA of cancer genomes, we explored the mutagenic threat of A1 cytidine deaminases to chromosomal DNA. Results Molecular cloning and expression of various A1 enzymes reveal that the cow, pig, dog, rabbit and mouse A1 have an intracellular ssDNA substrate specificity. However, among all the enzymes studied, mouse A1 appears to be singular, being able to introduce somatic mutations into nuclear DNA with a clear 5’TpC editing context, and to deaminate 5-methylcytidine substituted DNA which are characteristic features of the cancer related mammalian A3A and A3B enzymes. However, mouse A1 activity fails to elicit formation of double stranded DNA breaks, suggesting that mouse A1 possess an attenuated nuclear DNA mutator phenotype reminiscent of human A3B. Conclusions At an experimental level mouse APOBEC1 is remarkable among 12 mammalian A1 enzymes in that it represents a source of somatic mutations in mouse genome, potentially fueling oncogenesis. While the order Rodentia is bereft of A3A and A3B like enzymes it seems that APOBEC1 may well substitute for it, albeit remaining much less active. This modifies the paradigm that APOBEC3 and AID enzymes are the sole endogenous mutator enzymes giving rise to off-target editing of mammalian genomes.
    Type of Medium: Online Resource
    ISSN: 1471-2164
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2019
    detail.hit.zdb_id: 2041499-7
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Microbiology Society ; 2012
    In:  Journal of General Virology Vol. 93, No. 12 ( 2012-12-01), p. 2646-2651
    In: Journal of General Virology, Microbiology Society, Vol. 93, No. 12 ( 2012-12-01), p. 2646-2651
    Abstract: RNA editing mediated by adenosine deaminases acting on RNA (ADARs) converts adenosine (A) to inosine (I) residues in dsRNA templates. While ADAR-1-mediated editing was essentially described for RNA viruses, the present work addresses the issue for two δ-retroviruses, human T-cell leukemia virus type 2 and simian T-cell leukemia virus type 3 (HTLV-2 and STLV-3). We examined whether ADAR-1 could edit HTLV-2 and STLV-3 virus genomes in cell culture and in vivo . Using a highly sensitive PCR-based method, referred to as 3DI-PCR, we showed that ADAR-1 could hypermutate adenosine residues in HTLV-2. STLV-3 hypermutation was obtained without using 3DI-PCR, suggesting a higher mutation frequency for this virus. Detailed analysis of the dinucleotide editing context showed preferences for 5′ ArA and 5′ UrA. In conclusion, the present observations demonstrate that ADAR-1 massively edits HTLV-2 and STLV-3 retroviruses in vitro , but probably remains a rare phenomenon in vivo .
    Type of Medium: Online Resource
    ISSN: 0022-1317 , 1465-2099
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    Language: English
    Publisher: Microbiology Society
    Publication Date: 2012
    detail.hit.zdb_id: 2007065-2
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  • 3
    Online Resource
    Online Resource
    Microbiology Society ; 2005
    In:  Journal of General Virology Vol. 86, No. 1 ( 2005-01-01), p. 125-129
    In: Journal of General Virology, Microbiology Society, Vol. 86, No. 1 ( 2005-01-01), p. 125-129
    Abstract: Virus genomes from the same family may exhibit a wide range in their DNA GC content, whereas viral hypermutants differ substantially in GC content from their parental genomes. As AT-rich DNA melts at lower temperatures than GC-rich DNA, use of a lower denaturation temperature during PCR should allow differential amplification of AT-rich genomes or variants within a quasispecies. The latter situation has been explored explicitly in a two-step process by using a series of well-defined viral sequences differing in their AT content. Firstly, the lowest denaturation temperature ( T p ) that allowed amplification of the parental sequence was determined. Secondly, differential amplification of AT-rich viral variants was obtained by using a denaturation temperature 1–3 °C lower than T p . Application of this sensitive method to two different viruses allowed us to identify human immunodeficiency virus type 1 G→A hypermutants in a situation where none were expected and to amplify AT-rich variants selectively within a spectrum of poliovirus mutants.
    Type of Medium: Online Resource
    ISSN: 0022-1317 , 1465-2099
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    Language: English
    Publisher: Microbiology Society
    Publication Date: 2005
    detail.hit.zdb_id: 2007065-2
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    Microbiology Society ; 2002
    In:  Journal of General Virology Vol. 83, No. 4 ( 2002-04-01), p. 801-805
    In: Journal of General Virology, Microbiology Society, Vol. 83, No. 4 ( 2002-04-01), p. 801-805
    Abstract: Two full-length human immunodeficiency virus type 1 O sequences are described, one of which was hypermutated in all regions of the genome. This indicates that the intracellular [dTTP]/[dCTP] bias conducive to G→A hypermutation may be sustained throughout the synthesis of minus-strand DNA. In turn, this suggests the possibility of mutation of host sequences.
    Type of Medium: Online Resource
    ISSN: 0022-1317 , 1465-2099
    RVK:
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    Language: English
    Publisher: Microbiology Society
    Publication Date: 2002
    detail.hit.zdb_id: 2007065-2
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    American Association for the Advancement of Science (AAAS) ; 2008
    In:  Science Vol. 320, No. 5873 ( 2008-04-11), p. 230-233
    In: Science, American Association for the Advancement of Science (AAAS), Vol. 320, No. 5873 ( 2008-04-11), p. 230-233
    Abstract: Cytidine deaminases of the APOBEC3 family all have specificity for single-stranded DNA, which may become exposed during replication or transcription of double-stranded DNA. Three human APOBEC3A ( hA3A ), hA3B , and hA3H genes are expressed in keratinocytes and skin, leading us to determine whether genetic editing of human papillomavirus (HPV) DNA occurred. In a study of HPV1a plantar warts and HPV16 precancerous cervical biopsies, hyperedited HPV1a and HPV16 genomes were found. Strictly analogous results were obtained from transfection experiments with HPV plasmid DNA and the three nuclear localized enzymes: hA3A, hA3C, and hA3H. Thus, stochastic or transient overexpression of APOBEC3 genes may expose the genome to a broad spectrum of mutations that could influence the development of tumors.
    Type of Medium: Online Resource
    ISSN: 0036-8075 , 1095-9203
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    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2008
    detail.hit.zdb_id: 128410-1
    detail.hit.zdb_id: 2066996-3
    detail.hit.zdb_id: 2060783-0
    SSG: 11
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  • 6
    In: Journal of Virology, American Society for Microbiology, Vol. 81, No. 9 ( 2007-05), p. 4900-4903
    Abstract: The retroviral mutation rate is susceptible to a number of variables, including the balance between intracellular deoxynucleoside triphosphate (dNTP) pools. While this follows from tissue culture studies, the issue has never been addressed directly in vivo. To explore this question in a tractable experimental system, we analyzed the impact of thymidine treatment on the synthesis of gypsy retroelement cDNA from Drosophila melanogaster during development through to hatching. The mutation frequency was enhanced approximately 16-fold over the levels seen in the experimental background. Due to the lack of proofreading, these gypsy elements represent hypervariable loci within the Drosophila genome, suggesting that dNTP pool imbalances in vivo are mutagenic.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2007
    detail.hit.zdb_id: 1495529-5
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  • 7
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 1992
    In:  Nucleic Acids Research Vol. 20, No. 3 ( 1992), p. 521-523
    In: Nucleic Acids Research, Oxford University Press (OUP), Vol. 20, No. 3 ( 1992), p. 521-523
    Type of Medium: Online Resource
    ISSN: 0305-1048 , 1362-4962
    RVK:
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 1992
    detail.hit.zdb_id: 1472175-2
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  • 8
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 11, No. 1 ( 2021-04-12)
    Abstract: APOBEC3 (A3) enzymes are best known for their role as antiviral restriction factors and as mutagens in cancer. Although four of them, A3A, A3B, A3F and A3G, are induced by type-1-interferon (IFN-I), their role in inflammatory conditions is unknown. We thus investigated the expression of A3 , and particularly A3A and A3B because of their ability to edit cellular DNA, in Systemic Lupus Erythematosus (SLE), a chronic inflammatory disease characterized by high IFN-α serum levels. In a cohort of 57 SLE patients, A3A and A3B, but also A3C and A3G, were upregulated ~ 10 to 15-fold ( 〉  1000-fold for A3B ) compared to healthy controls, particularly in patients with flares and elevated serum IFN-α levels. Hydroxychloroquine, corticosteroids and immunosuppressive treatment did not reverse A3 levels. The A3AΔ3B polymorphism, which potentiates A3A , was detected in 14.9% of patients and in 10% of controls, and was associated with higher A3A mRNA expression. A3A and A3B mRNA levels, but not A3C or A3G , were correlated positively with dsDNA breaks and negatively with lymphopenia. Exposure of SLE PBMCs to IFN-α in culture induced massive and sustained A3A levels by 4 h and led to massive cell death. Furthermore, the rs2853669 A  〉  G polymorphism in the telomerase reverse transcriptase (TERT) promoter, which disrupts an Ets-TCF-binding site and influences certain cancers, was highly prevalent in SLE patients, possibly contributing to lymphopenia. Taken together, these findings suggest that high baseline A3A and A3B levels may contribute to cell frailty, lymphopenia and to the generation of neoantigens in SLE patients. Targeting A3 expression could be a strategy to reverse cell death and the generation of neoantigens.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 2615211-3
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  • 9
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2019
    In:  Scientific Reports Vol. 9, No. 1 ( 2019-01-24)
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 9, No. 1 ( 2019-01-24)
    Abstract: The incidence of developing cancer should increase with the body mass, yet is not the case, a conundrum referred to as Peto’s paradox. Elephants have a lower incidence of cancer suggesting that these animals have probably evolved different ways to protect themselves against the disease. The paradox is worth revisiting with the realization that most mammals encode an endogenous APOBEC3 cytidine deaminase capable of mutating single stranded DNA. Indeed, the mutagenic activity of some APOBEC3 enzymes has been shown to introduce somatic mutations into genomic DNA. These enzymes are now recognized as causal agent responsible for the accumulation of CG-  〉  TA transitions and DNA breaks leading to chromosomal rearrangements in human cancer genomes. Here, we identified an elephant A3Z1 gene, related to human APOBEC3A and showed that it could efficiently deaminate cytidine, 5-methylcytidine and produce DNA breaks leading to massive apoptosis, similar to other mammalian APOBEC3A enzymes where body mass varies by up to four orders of magnitude. Consequently, it could be considered that eAZ1 might contribute to cancer in elephants in a manner similar to their proposed role in humans. If so, eAZ1 might be particularly well regulated to counter Peto’s paradox.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2019
    detail.hit.zdb_id: 2615211-3
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  • 10
    In: Journal of Virology, American Society for Microbiology, Vol. 85, No. 5 ( 2011-03), p. 2458-2462
    Abstract: We sought to examine ADAR-1 editing of measles and influenza virus genomes derived from inactivated seasonal influenza and live attenuated measles virus vaccines grown on chicken cells as the culture substrate. Using highly sensitive 3DI-PCR (R. Suspène et al., Nucleic Acids Res. 36:e72, 2008), it was possible to show that ADAR-1 could hyperdeaminate adenosine residues in both measles virus and influenza virus A genomes. Detailed analysis of the dinucleotide editing context showed preferences for 5′ArA and 5′UrA, which is typical of editing in mammalian cells. The hyperedited mutant frequency, including genomes and antigenomes, was a log greater for influenza virus compared to measles virus, suggesting a greater sensitivity to restriction by ADAR-1.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2011
    detail.hit.zdb_id: 1495529-5
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