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Bertzbach LD, Ip WH, Dobner T. Animal Models in Human Adenovirus Research. BIOLOGY 2021; 10:biology10121253. [PMID: 34943168 PMCID: PMC8698265 DOI: 10.3390/biology10121253] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 11/24/2021] [Accepted: 11/30/2021] [Indexed: 12/31/2022]
Abstract
Simple Summary Animal models are widely used to study various aspects of human diseases and disorders. Likewise, they are indispensable for preclinical testing of medicals and vaccines. Human adenovirus infections are usually self-limiting, and can cause mild respiratory symptoms with fever, eye infection or gastrointestinal symptoms, but occasional local outbreaks with severe disease courses have been reported. In addition, adenovirus infections pose a serious risk for children and patients with a weakened immune system. Human adenovirus research in animal models to study adenovirus-induced disease and tumor development started in the 1950s. Various animal species have been tested for their susceptibility to human adenovirus infection since then, and some have been shown to mimic key characteristics of the infection in humans, including persistent infection. Furthermore, some rodent species have been found to develop tumors upon human adenovirus infection. Our review summarizes the current knowledge on animal models in human adenovirus research, describing the pros and cons along with important findings and future perspectives. Abstract Human adenovirus (HAdV) infections cause a wide variety of clinical symptoms, ranging from mild upper respiratory tract disease to lethal outcomes, particularly in immunocompromised individuals. To date, neither widely available vaccines nor approved antiadenoviral compounds are available to efficiently deal with HAdV infections. Thus, there is a need to thoroughly understand HAdV-induced disease, and for the development and preclinical evaluation of HAdV therapeutics and/or vaccines, and consequently for suitable standardizable in vitro systems and animal models. Current animal models to study HAdV pathogenesis, persistence, and tumorigenesis include rodents such as Syrian hamsters, mice, and cotton rats, as well as rabbits. In addition, a few recent studies on other species, such as pigs and tree shrews, reported promising data. These models mimic (aspects of) HAdV-induced pathological changes in humans and, although they are relevant, an ideal HAdV animal model has yet to be developed. This review summarizes the available animal models of HAdV infection with comprehensive descriptions of virus-induced pathogenesis in different animal species. We also elaborate on rodent HAdV animal models and how they contributed to insights into adenovirus-induced cell transformation and cancer.
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Swindle S. Biosafety in Handling Gene Transfer Vectors. ACTA ACUST UNITED AC 2018; 96:12.1.1-12.1.17. [DOI: 10.1002/cphg.54] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Scott Swindle
- Occupational Medicine and Research Safety, The University of Alabama at Birmingham Birmingham Alabama
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Discoveries in Molecular Genetics with the Adenovirus 12 System: Integration of Viral DNA and Epigenetic Consequences. EPIGENETICS OF INFECTIOUS DISEASES 2017. [PMCID: PMC7120421 DOI: 10.1007/978-3-319-55021-3_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Starting in the 1960s, the human adenovirus type 12 (Ad12) system has been used in my laboratory to investigate basic mechanisms in molecular biology and viral oncology. Ad12 replicates in human cells but undergoes a completely abortive cycle in Syrian hamster cells. Ad12 induces neuro-ectodermal tumors in newborn hamsters (Mesocricetus auratus). Each tumor cell or Ad12-transformed hamster cell carries multiple copies of integrated Ad12 DNA. Ad12 DNA usually integrates at one chromosomal site which is not specific since Ad12 DNA can integrate at many different locations in the hamster genome. Epigenetic research occupies a prominent role in tumor biology. We have been using the human Ad12 Syrian hamster cell system for the analysis of epigenetic alterations in Ad12-infected cells and in Ad12-induced hamster tumors. Virion or free intracellular Ad12 DNA remains unmethylated at CpG sites, whereas the integrated viral genomes become de novo methylated in specific patterns. Inverse correlations between promoter methylation and activity were described for the first time in this system and initiated active research in the field of DNA methylation and epigenetics. Today, promoter methylation has been recognized as an important factor in long-term genome silencing. We have also discovered that the insertion of foreign (Ad12, bacteriophage lambda, plasmid) DNA into mammalian genomes can lead to genome-wide alterations in methylation and transcription patterns in the recipient genomes. This concept has been verified recently in a pilot study with human cells which had been rendered transgenomic for a 5.6 kbp bacterial plasmid. Currently, we study epigenetic effects on cellular methylation and transcription patterns in Ad12-infected cells and in Ad12-induced hamster tumor cells. These epigenetic alterations are considered crucial elements in (viral) oncogenesis.
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Doerfler W. Epigenetic consequences of foreign DNA insertions: de novo methylation and global alterations of methylation patterns in recipient genomes. Rev Med Virol 2011; 21:336-46. [PMID: 21793096 DOI: 10.1002/rmv.698] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 05/04/2011] [Accepted: 05/19/2011] [Indexed: 11/09/2022]
Abstract
The insertion of foreign DNA into mammalian or plant genomes is a frequent event in biology. My laboratory has pursued a long-standing interest in the structure of integrated adenovirus genomes and in the mechanism of foreign DNA insertions in mammalian cells. The long-term consequences of the integration of alien DNA are only partly known, and even less well understood are the mechanisms that bring them about. Evidence from viral systems has contributed to the realization that foreign DNA insertions entail a complex of sequelae that have also become apparent in non-viral systems: (i) The de novo methylation of integrated foreign DNA sequences has frequently been observed. (ii) Alterations of DNA methylation patterns in the recipient genome at and remote from the site of foreign DNA insertion have been demonstrated but it remains to be investigated how generally this phenomenon occurs. Many viral genomes find and have found entry into the genomes of present-day organisms. A major portion of mammalian genomes represents incomplete retroviral genomes that frequently have become permanently silenced by DNA methylation. It is still unknown how and to what extent the insertion of retroviral or retrotransposon sequences into established genomes has altered and shaped the methylation and transcription profiles of present day genomes. An additional reason for concern about the effects of foreign DNA integration is the fact that in all fields of molecular biology and medicine, the generation of transgenic or transgenomic cells and organisms has become a ubiquitously applied experimental technique.
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Affiliation(s)
- Walter Doerfler
- Institute for Clinical and Molecular Virology, Erlangen University Medical School, Erlangen, Germany; Institute of Genetics, Cologne University, Cologne, Germany.
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Poreba E, Broniarczyk JK, Gozdzicka-Jozefiak A. Epigenetic mechanisms in virus-induced tumorigenesis. Clin Epigenetics 2011; 2:233-47. [PMID: 22704339 PMCID: PMC3365383 DOI: 10.1007/s13148-011-0026-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Accepted: 02/28/2011] [Indexed: 12/14/2022] Open
Abstract
About 15–20% of human cancers worldwide have viral etiology. Emerging data clearly indicate that several human DNA and RNA viruses, such as human papillomavirus, Epstein–Barr virus, Kaposi’s sarcoma-associated herpesvirus, hepatitis B virus, hepatitis C virus, and human T-cell lymphotropic virus, contribute to cancer development. Human tumor-associated viruses have evolved multiple molecular mechanisms to disrupt specific cellular pathways to facilitate aberrant replication. Although oncogenic viruses belong to different families, their strategies in human cancer development show many similarities and involve viral-encoded oncoproteins targeting the key cellular proteins that regulate cell growth. Recent studies show that virus and host interactions also occur at the epigenetic level. In this review, we summarize the published information related to the interactions between viral proteins and epigenetic machinery which lead to alterations in the epigenetic landscape of the cell contributing to carcinogenesis.
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Affiliation(s)
- Elzbieta Poreba
- Department of Molecular Virology, Adam Mickiewicz University, Umultowska 89, 61-614, Poznan, Poland
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Whiteside MA, Siegel EM, Unger ER. Human papillomavirus and molecular considerations for cancer risk. Cancer 2008; 113:2981-94. [PMID: 18980282 DOI: 10.1002/cncr.23750] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Human papillomaviruses (HPVs) are a major cause of cancer globally, including cervical cancer. The HPV 'early' proteins, E6 and E7, are the chief oncoproteins involved in cancer progression. These oncoproteins are more highly expressed in high-grade dysplasias and invasive cancer coincident with reduced viral DNA replication and reduced production of infective progeny virions. The E6 and E7 oncoproteins interact with several cellular proteins-classically TP53 and RB1, respectively-leading to the degradation of several of these proteins, although all interactions do not necessarily result in the degradation of a cellular protein. HPV infection is also associated with viral and host DNA methylation changes, many of which also occur in cancer types not associated with HPV infection. The E6 and E7 interactions with cellular proteins and DNA methylation changes are associated with changes in the integrity of key cellular pathways that regulate genomic integrity, cell adhesion, the immune response, apoptosis, and cell cycle control. The alterations in key cellular pathways may provide useful biomarkers to improve the sensitivity of current cancer screening methods, such as the Papanicolaou test. This review provides a detailed summary of the interactions of E6 and E7 with cellular proteins and alterations in cellular DNA methylation associated with HPV infection. The importance of molecular biomarkers to the clinical setting, underserved populations, and general public health is discussed.
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Affiliation(s)
- Martin A Whiteside
- Office of Cancer Surveillance, Tennessee Department of Health, Nashville, Tennessee 37243, USA.
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Abstract
This unit is devoted to safety issues that must be considered when generating and working with vectors for gene therapy. A short description of the relevant regulatory bodies and mechanisms is followed by a general discussion of containment and safety procedures. This is followed by vector-specific guidelines for nine commonly used vector systems, including adenovirus, vaccinia, HSV-1, lentivirus, and nonviral vectors. Recent tragic experiences with retroviral integration near oncogene loci demonstrate the surprise effects of successful gene therapy. The unit also outlines the problems encountered when taking a promising vector to clinical trials.
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Affiliation(s)
- Andrew Braun
- Harvard Medical School, Boston, Massachusetts, USA
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Doerfler W. Human Adenovirus Type 12. METHODS IN MOLECULAR MEDICINE™ 2007. [PMCID: PMC7120018 DOI: 10.1007/978-1-59745-277-9_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
When viruses cross species barriers, they often change their biological and pathogenetic properties. In the author's laboratory the nonproductive interaction of Syrian hamster cells with human adenovirus type 12 (Ad12) has been studied. Ad12 induces undifferentiated tumors in newborn hamsters (Mesocricetus auratus) at high frequency. Ad12 inefficiently enters hamster (BHK21) cells, and only small amounts of viral DNA reach the nucleus. Viral DNA replication and late transcription are blocked. In Ad12-induced tumor cells, multiple copies of viral DNA are chromosomally integrated. The integrated viral DNA becomes de novo methylated. Cellular DNA methylation and transcription patterns in Ad12-transformed cells and in Ad12- induced tumor cells are altered. These changes may be related to the oncogenic potential of Ad12 in hamsters. In this chapter, concepts and techniques for the study of the Ad12-hamster cell system are summarized.
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Doerfler W. De novo methylation, long-term promoter silencing, methylation patterns in the human genome, and consequences of foreign DNA insertion. Curr Top Microbiol Immunol 2006; 301:125-75. [PMID: 16570847 DOI: 10.1007/3-540-31390-7_5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
This chapter presents a personal account of the work on DNA methylation in viral and mammalian systems performed in the author's laboratory in the course of the past 30 years. The text does not attempt to give a complete and meticulous account of the work accomplished in many other laboratories; in that sense it is not a review of the field in a conventional sense. Since the author is also one of the editors of this series of Current Topics in Immunology and Microbiology on DNA methylation, to which contributions by many of our colleagues in this field have been invited, the author's conscience is alleviated that he has not cited many of the relevant and excellent reports by others. The choice of viral model systems in molecular biology is well founded. Over many decades, viruses have proved their invaluable and pioneering role as tools in molecular genetics. When our interest turned to the demonstration of genome-wide patterns of DNA methylation, we focused mainly on the human genome. The following topics in DNA methylation will be treated in detail: (1) The de novo methylation of integrated foreign genomes; (2) the long-term gene silencing effect of sequence-specific promoter methylation and its reversal; (3) the properties and specificity of patterns of DNA methylation in the human genome and their possible relations to pathogenesis; (4) the long-range global effects on cellular DNA methylation and transcriptional profiles as a consequence of foreign DNA insertion into an established genome; (5) the patterns of DNA methylation can be considered part of a cellular defense mechanism against foreign or repetitive DNA; which role has food-ingested DNA played in the elaboration of this mechanism? The interest in problems related to DNA methylation has spread-like the mechanism itself-into many neighboring fields. The nature of the transcriptional programs orchestrating embryonal and fetal development, chromatin structure, genetic imprinting, genetic disease, X chromosome inactivation, and tumor biology are but a few of the areas of research that have incorporated studies on the importance of the hitherto somewhat neglected fifth nucleotide in many genomes. Even the fly researchers now have to cope with the presence of this nucleotide, in however small quantities it exists in the genome of their model organism, at least during embryonal development. The bulk of the experimental work accomplished in the author's laboratory has been shouldered by many very motivated undergraduate and graduate students and by a number of talented postdoctoral researchers. Their contributions are reflected in the list of references in this chapter. We have also had the good luck to receive funding through a number or organizations as acknowledged.
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Affiliation(s)
- W Doerfler
- Institut für Genetik, Universität zu Köln, Germany.
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10
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Doerfler W. On the biological significance of DNA methylation. BIOCHEMISTRY (MOSCOW) 2005; 70:505-24. [PMID: 15948705 DOI: 10.1007/s10541-005-0145-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
This chapter presents a personal account of the work on DNA methylation in viral and mammalian systems performed in the author's laboratory in the course of the past thirty years. The text does not attempt to give a complete and meticulous account of the many relevant and excellent reports published by many other laboratories, so it is not a review of the field in a conventional sense. The choice of viral model systems in molecular biology is well founded. Over many decades, viruses have proven their invaluable and pioneering role as tools in molecular genetics. When our interest turned to the demonstration of genome-wide patterns of DNA methylation, we focused mainly on the human genome. The following topics in DNA methylation will be treated in detail: (i) the de novo methylation of integrated foreign genomes; (ii) the long-term gene silencing effect of sequence-specific promoter methylation and its reversal; (iii) the properties and specificity of patterns of DNA methylation in the human genome and their possible relations to pathogenesis; (iv) the long-range global effects on cellular DNA methylation and transcriptional profiles as a consequence of foreign DNA insertion into an established genome; (v) the patterns of DNA methylation can be considered part of a cellular defense mechanism against foreign or repetitive DNA; what role has food-ingested DNA played in the elaboration of this mechanism?
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Affiliation(s)
- W Doerfler
- Institut für Genetik, Universität zu Köln, 50674 Köln, Germany.
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Zhou Y, Bosch ML, Salgaller ML. Current methods for loading dendritic cells with tumor antigen for the induction of antitumor immunity. J Immunother 2002; 25:289-303. [PMID: 12142552 DOI: 10.1097/00002371-200207000-00001] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The immunotherapy of cancer is predicated on the belief that it is possible to generate a clinically meaningful antitumor response that provides patient benefit, such as improvement in the time to progression or survival. Indeed, immunotherapeutics with dendritic cells (DC) as antigen-presenting delivery vehicles for cell-based vaccines have already improved patient outcome against a wide range of tumor types (1-9). This approach stimulates the patient's own antitumor immunity through the induction or enhancement of T-cell immunity. It is generally believed that the activity of cytotoxic T lymphocytes (CTL), the cells directly responsible for killing the tumor cells in vivo, are directed by DC. Therefore, the goal of many current designs for DC-based vaccines is to induce strong tumor-specific CTL responses in patients with cancer. In practice, most studies for DC-based cancer vaccine development have focused on the development of methods that can effectively deliver exogenous tumor antigens to DC for cross-priming of CD8+ T cells through the endogenous MHC class I processing and presentation pathway (10). To date, many methods have been developed or evaluated for the delivery of defined and undefined tumor antigens to DC. This review provides a brief summary on these methods, the techniques used in these methods, as well as the advantages and disadvantages of each method.
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Affiliation(s)
- Yaling Zhou
- Northwest Biotherapeutics, Incorporated, Bothell, Washington 98021, USA
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12
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Hösel M, Schröer J, Webb D, Jaroshevskaja E, Doerfler W. Cellular and early viral factors in the interaction of adenovirus type 12 with hamster cells: the abortive response. Virus Res 2001; 81:1-16. [PMID: 11682120 DOI: 10.1016/s0168-1702(01)00242-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The interaction of human adenovirus type 12 (Ad12) with Syrian hamster cells is remarkable in that there is a block of viral DNA replication and late gene transcription. We have screened several cellular factors known to play a role in adenovirus replication for their possible contributions to the interactions of Ad12 in the abortive BHK21 hamster cell system. (1) Western blot analyses of total protein extracts from Ad12- or Ad2-infected BHK21 cells do not reveal a significant difference in the accumulation of NFIII protein at different times after infection. Transcriptional levels of the NFIII gene in BHK21 cells are not altered upon the abortive infection with Ad12 or the productive infection with Ad2. The amount of NFIII protein is markedly reduced in nuclear extracts from BHK21 cells as compared with extracts from C131 hamster cells or human HeLa cells. A presumptive defect in NFIII transport to the nuclei rather than overall reduced NFIII gene transcription might explain the low abundance of NFIII in the nuclei of uninfected or Ad12-infected BHK21 cells. The productive infection of BHK21 or C131 cells with Ad2 leads to an increase in the NFIII concentration in the nuclei of infected cells, late after infection to a decrease; (2) NFI levels in the nuclei of mock-infected or Ad2- or Ad12-infected BHK21 cells are comparable with those in HeLa or in C131 cells. Thus, deficiencies in NFI may not play a role in the abortive system; (3) The absence of morphological alterations in PML protein domains from globular to track-like structures in the nuclei of Ad12-infected hamster cells correlates with the inability of Ad12 DNA to replicate in BHK21 cells. In BHK21 cells, the E4-ORF3 of Ad12 DNA is only weakly transcribed and only small amounts of the gene product are synthesized. In Ad12-infected C131 cells, which allow the replication of Ad12 DNA, the E4-ORF3 of Ad12 DNA is expressed, and track-like PML protein structures are observed. Transfection of the 12-E4-ORF3-EGFP construct leads to the expression of both the green fluorescent protein (GFP) and of the 12-E4-ORF3 gene product in 20-30% of the transfected BHK21 cells and elicits the morphological reorganization of the PML protein structures in the successfully transfected BHK21 cells. Similar results are obtained upon transfection of the 2-E4-ORF3 construct. Untransfected cells or cells transfected with the empty pIRES2-pEGFP vector carry the globular PML protein phenotype; (4) The expression of the 12-E4-ORF3-EGFP and/or of the NFIII-EGFP constructs upon transfection following Ad12-infection of BHK21 cells fails to promote Ad12 DNA replication. Hence, the formation of track-like PML protein structures in BHK21 cells by itself is not a sufficient precondition for Ad12 DNA replication in this abortive system. The data demonstrate that the expression of NFI, NFIII, and/or the conversion of the PML domains do not suffice to elicit Ad12 DNA replication in the abortive hamster cell system.
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Affiliation(s)
- M Hösel
- Institute for Genetics, University of Cologne, Weyertal 121, D-50931, Koeln, Germany
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Harui A, Suzuki S, Kochanek S, Mitani K. Frequency and stability of chromosomal integration of adenovirus vectors. J Virol 1999; 73:6141-6. [PMID: 10364373 PMCID: PMC112682 DOI: 10.1128/jvi.73.7.6141-6146.1999] [Citation(s) in RCA: 219] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
One of the limitations of adenovirus vectors is the lack of machinery necessary for their integration into host chromosomes, resulting in short-term gene expression in dividing cells. We analyzed frequencies of integration and persistence of gene expression from integrated adenovirus vectors. Both E1-substituted and helper-dependent adenovirus vectors achieved similar integration efficiencies of approximately 10(-3) to 10(-5) per cell, with the helper-dependent vector showing slightly higher efficiencies. In stable cell pools, gene expression of the integrated vector persisted for at least 50 cell divisions without selection. However, some stable cell clones showed changes in gene expression, which were accompanied by structural changes in the integrated vector DNA.
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Affiliation(s)
- A Harui
- Department of Microbiology, Immunology and Molecular Genetics, UCLA School of Medicine, Los Angeles, California 90095-1747, USA
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Abstract
Gene therapy of malignant diseases can be divided into four basic approaches: gene interference, gene insertion, immunopotentiation, and suicide gene approaches. This article reviews the application of these approaches in the therapy of leukemias and lymphomas.
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Affiliation(s)
- S W Adams
- Division of Hematology/Oncology, Children's Hospital of Philadelphia, Pennsylvania, USA
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Trabanelli C, Corallini A, Gruppioni R, Sensi A, Bonfatti A, Campioni D, Merlin M, Calza N, Possati L, Barbanti-Brodano G. Chromosomal aberrations induced by BK virus T antigen in human fibroblasts. Virology 1998; 243:492-6. [PMID: 9568046 DOI: 10.1006/viro.1998.9080] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Human fibroblasts, transfected with a recombinant DNA containing the neo gene and BK virus (BKV) early region, which expresses BPV large T antigen (TAg), show cytogenetic alterations characterized by dicentric chromosomes and other structural aberrations such as deletions, duplications, translocations, and ring chromosomes. Such alterations were absent or significantly less frequent in human fibroblasts transfected with a plasmid expressing only the neo gene. The chromosome damage in BKV-transfected cells was evident before the appearance of the morphologically transformed phenotype and therefore seems to be a primary effect of TAg expression in human cells. The specific pattern of chromosome aberrations suggests the prevalence of an indirect clastogenic effect, determined by the inhibition of p53 regulatory functions on genome stability by BKV TAg. Due to the widespread distribution of BKV in the human population and to the latent state of BKV DNA in many human organs, the clastogenic activity of BKV TAg may potentially participate in an oncogenic process involving BKV latently infected cells.
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Affiliation(s)
- C Trabanelli
- Department of Experimental and Diagnostic Medicine, University of Ferrara, Italy
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Abstract
It is now generally accepted that the presence of 5-methylcytosine (5mC) in human DNA has both a genetic and an epigenetic effect on cellular development, differentiation and transformation. First, 5mC is more unstable than its unmethylated counterpart cytosine. Hydrolytic deamination of 5mC leads to a G/T mismatch and subsequently, if unrepaired, to a C-->T transition mutation. Sites of DNA methylation are mutational hotspots in many human tumors. Second, DNA methylation of promoter regions is often correlated with the down regulation of the corresponding gene. Both of these effects have fundamental consequences for basic functions of the cell like cellular differentiation, the development of cancer and possibly other diseases, and on the evolutionary process. Recent hypotheses also propose a role for methylation in the process of aging. In this review we will describe recent findings and hypotheses about the function of 5mC in DNA with the focus on its involvement in human carcinogenesis.
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Affiliation(s)
- C Schmutte
- Thomas Jefferson University, Kimmel Cancer Center, Philadelphia, PA 19107, USA
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Lea N, Mufti GJ. The Scope of Viral Vectors for the Transduction of Haemopoietic Cells. Hematology 1998; 3:37-53. [PMID: 27416282 DOI: 10.1080/10245332.1998.11746378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Over the last five years significant progress has been made towards the transfer of foreign genetic material to eukaryotic cells. The eventual aim to devise novel therapeutic strategies to treat human diseases, in particular solid tumours and monogenic disorders associated with various enzyme deficiency states. The easy accessibility and the ability of haemopoetic stem cells to self replicate and repopulate makes them desirable targets for gene transfer. In theory the introduction of a small number of gene modifed haemopoetic progenitor cells can allow therapy of an individual for life without any further intervention. This approach has been used for the treatment of single gene defects such as ADA deficiency. Furthermore, gene transfer technology has increasingly been exploited for bone marrow and peripheral blood stem cell marking studies, modification of cell sensitivity to cytotoxic drugs and the genetic modification of leukemic cells with the intention of inducing a leukemia specific cytotoxic T cell response. Vector development is of crucial importance for the successful delivery of genes in haemopoetic stem cells and leukemia cells. The objective of this review is to discuss in detail the properties of current vector technology that are pertinent to haemopoietic cell gene transduction.
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Affiliation(s)
- N Lea
- a Post-doctoral Research fellow Myeloid gene therapy programme, Department of Haematological Medicine , King's College Hospital, School of medicine and dentistry , Denmark Hill, London SE5 8RX
| | - G J Mufti
- b Professor of Haemato-oncology, Department of Haematological Medicine , King's College Hospital, School of medicine and dentistry , Denmark Hill, London SE5 8RX
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Kim DH, Chang JH, Lee KH, Lee HY, Kim SJ. Mechanism of E1A-induced transforming growth factor-beta (TGF-beta) resistance in mouse keratinocytes involves repression of TGF-beta type II receptor transcription. J Biol Chem 1997; 272:688-94. [PMID: 8995313 DOI: 10.1074/jbc.272.1.688] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Cellular transformation driven by the E1A oncogene is associated with the development of cellular resistance to the growth inhibitory effects of transforming growth factor-beta (TGF-beta). We demonstrate that development of resistance occurs simultaneously with decreased expression of TGF-beta type II receptor (TGF-beta RII) mRNA and protein. To determine whether changes in transcriptional regulation are responsible for the decreased receptor expression in E1A-transformed cells, a series of mobility shift assays was performed utilizing nuclear extracts from E1A-transformed and untransformed murine keratinocytes using radiolabeled positive regulatory elements (PRE1 and PRE2) of the TGF-beta RII promoter. The results from these assays suggest that E1A-transformed cells express markedly lower levels of nuclear proteins that bind specifically to PRE1 and PRE2. Transfection of both E1A-transformed and untransformed cell lines with a series of mutant promoter constructs confirmed that both PREs contribute significantly to basal expression of TGF-beta RII and that inactivation of either element leads to markedly reduced promoter activity. We conclude that development of TGF-beta resistance in E1A-transformed cells is achieved in part through transcriptional down-regulation of the TGF-beta RII gene and that this down-regulation is the result of decreased expression of unidentified transcription factor complexes that interact with PRE1 and PRE2.
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Affiliation(s)
- D H Kim
- Laboratory of Chemoprevention, NCI, National Institutes of Health, Bethesda, Maryland 20892-5055, USA
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Parmiani G, Colombo MP, Melani C, Arienti F. Cytokine gene transduction in the immunotherapy of cancer. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1997; 40:259-307. [PMID: 9217928 DOI: 10.1016/s1054-3589(08)60142-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- G Parmiani
- Gene Therapy Program, Istituto Nazionale Tumori, Milan, Italy
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20
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Doerfler W. A new concept in (adenoviral) oncogenesis: integration of foreign DNA and its consequences. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1288:F79-99. [PMID: 8876634 DOI: 10.1016/0304-419x(96)00024-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A new concept for viral oncogenesis is presented which is based on experimental work on the chromosomal integration of adenovirus DNA into mammalian genomes. The mechanism of adenovirus DNA integration is akin to non-sequence-specific insertional recombination in which patch homologies between the recombination partners are frequently observed. This reaction has been imitated in a cell-free system by using nuclear extracts from hamster cells and partly purified fractions derived from them. As a consequence of foreign DNA insertion into the mammalian genome, the foreign DNA is extensively de novo methylated in specific patterns, presumably as part of a mammalian host cell defense mechanism against inserted foreign DNA which can be permanently silenced in this way. A further corollary of foreign (adenovirus or bacteriophage lambda) DNA integration is seen in extensive changes in cellular DNA methylation patterns at sites far remote from the locus of insertional recombination. Repetitive cellular, retrotransposon-like sequences are particularly, but not exclusively, prone to these increases in DNA methylation. It is conceivable that these changes in DNA methylation are a reflection of a profound overall reorganization process in the affected genomes. Could these alterations significantly contribute to the transformation events during viral or other types of oncogenesis? These sequelae of foreign DNA integration into established mammalian genomes will have to be critically considered when interpreting results obtained with transgenic, knock-out, and knock-in animals and when devising schemes for human somatic gene therapy. The interpretation of de novo methylation as a cellular defense mechanism has prompted investigations on the fate of food-ingested foreign DNA. The gastrointestinal (GI) tract provides a large surface for the entry of foreign DNA into any organism. As a tracer molecule, bacteriophage M13 DNA has been fed to mice. Fragments of this DNA can be found in small amounts (about 1% of the administered DNA) in all parts of the intestinal tract and in the feces. Furthermore, M13 DNA can be traced in the columnar epithelia of the intestine, in Peyer's plaque leukocytes, in peripheral white blood cells, in spleen, and liver. Authentic M13 DNA has been recloned from total spleen DNA. If integrated, this DNA might elicit some of the described consequences of foreign DNA insertion into the mammalian genome. Food-ingested DNA will likely infiltrate the organism more frequently than viral DNA.
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Affiliation(s)
- W Doerfler
- Institut für Genetik, Universität zu Köln, Germany.
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Hohn T, Corsten S, Rieke S, Müller M, Rothnie H. Methylation of coding region alone inhibits gene expression in plant protoplasts. Proc Natl Acad Sci U S A 1996; 93:8334-9. [PMID: 8710871 PMCID: PMC38671 DOI: 10.1073/pnas.93.16.8334] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Derivatives of the cauliflower mosaic virus 35S promoter lacking CG and CNG methylation targets were constructed and used to direct transcription of reporter gene constructs in transiently transformed protoplasts. Such methylation-target-free (MTF) promoters, although weaker than the 35S promoter, retain significant activity despite mutation of the as-1 element. The effect of methylation on gene expression in MTF- and 35S-promoter driven constructs was examined. Even when the promoter region was free of methylation targets, reporter gene expression was markedly reduced when cytosine residues in CG dinucleotides were methylated in vitro prior to transformation. Mosaic methylation experiments, in which only specific parts of the plasmids were methylated, revealed that methylation of the coding region alone has a negative effect on reporter gene expression. Methylation nearer the 5' end of the coding region was more inhibitory, consistent with inhibition of transcription elongation.
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Affiliation(s)
- T Hohn
- Friedrich Miescher Institute, Basel, Switzerland
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Affiliation(s)
- M Alt
- Department of Virus Research, Max-Planck-Institut fur Biochemie, Martinsried, Germany
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Fujita A, Sakagami K, Kanegae Y, Saito I, Kobayashi I. Gene targeting with a replication-defective adenovirus vector. J Virol 1995; 69:6180-90. [PMID: 7666520 PMCID: PMC189515 DOI: 10.1128/jvi.69.10.6180-6190.1995] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Wide application of the gene-targeting technique has been hampered by its low level of efficiency. A replication-defective adenovirus vector was used for efficient delivery of donor DNA in order to bypass this problem. Homologous recombination was selected between a donor neo gene inserted in the adenovirus vector and a target mutant neo gene on a nuclear papillomavirus plasmid. These recombinant adenoviruses allowed gene transfer to 100% of the treated cells without impairing their viability. Homologous recombinants were obtained at a level of frequency much higher than that obtained by electroporation or a calcium phosphate procedure. The structure of the recombinants was analyzed in detail after recovery in an Escherichia coli strain. All of the recombinants examined had experienced a precise correction of the mutant neo gene. Some of them had a nonhomologous rearrangement of their sequences as well. One type of nonhomologous recombination took place at the end of the donor-target homology. The vector adenovirus DNA was inserted into some of the products obtained at a high multiplicity of infection. The insertion was at the end of the donor-target homology with a concomitant insertion of a 10-bp-long filler sequence in one of the recombinants. The possible relationship between these rearrangements and the homologous recombination is discussed. These results demonstrate the applicability of adenovirus-mediated gene delivery in gene targeting and gene therapy.
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Affiliation(s)
- A Fujita
- Department of Molecular Biology, University of Tokyo, Japan
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Doerfler W, Orend G, Schubbert R, Fechteler K, Heller H, Wilgenbus P, Schröer J. On the insertion of foreign DNA into mammalian genomes: mechanism and consequences. Gene 1995; 157:241-5. [PMID: 7607499 DOI: 10.1016/0378-1119(95)00080-p] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We have studied the integration of adenovirus type 12 (Ad12) DNA in transformed and hamster tumor cells over many years. Upon infection of hamster cells with Ad12, viral DNA has been found in association with hamster chromosomes, possibly in part integrated into the host genome. Ad12 DNA integration is not sequence specific. Transcriptionally active sites of the host genome show a preponderance for foreign DNA insertion. We are pursuing the mechanism of Ad12 DNA integrative recombination in a cell-free system prepared from hamster cell nuclear extracts. In a number of Ad12-transformed hamster cell lines or in cell lines carrying foreign DNA, we have located the inserted Ad12 DNA copies on hamster chromosomes by fluorescent in situ hybridization (FISH). Among the consequences of Ad12 DNA integration, we have studied the de novo methylation of the integrated foreign (Ad12) DNA and increases in DNA methylation in several cellular genes and DNA segments in Ad12-transformed and hamster tumor cells. Several lines of evidence argue for the notion that parameters in addition to nucleotide sequence, in particular site of integration and/or the chromatin configuration of the integrated DNA, are important in generating de novo methylation patterns. The de novo methylation of integrated foreign DNA can be interpreted as an old cellular defense mechanism against the activity of foreign genes in an established genome. Pursuing this concept, we have asked for the most likely portal of entry of foreign DNA, supposedly the gastrointestinal tract in most animals. This hypothesis has been tested by feeding mice linearized or circular, double-stranded bacteriophage M13mp18 DNA.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- W Doerfler
- Institut für Genetik, Universität zu Köln, Germany
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Orend G, Knoblauch M, Kämmer C, Tjia ST, Schmitz B, Linkwitz A, Meyer G, Maas J, Doerfler W. The initiation of de novo methylation of foreign DNA integrated into a mammalian genome is not exclusively targeted by nucleotide sequence. J Virol 1995; 69:1226-42. [PMID: 7815498 PMCID: PMC188696 DOI: 10.1128/jvi.69.2.1226-1242.1995] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The de novo methylation of foreign DNA integrated into the mammalian genome is a fundamental process whose mechanism has not yet been elucidated. We have studied de novo methylation in adenovirus type 12 (Ad12) genomes inserted into the genomes of Ad12-induced hamster tumor cells. De novo methylation of Ad12 DNA, which is not methylated in the virion, is initiated in two paracentrally located regions and spreads from there across the integrated Ad12 genomes. (i) After extensive cultivation of cloned Ad12-induced hamster tumor cell lines, the same segments in integrated Ad12 DNA in different cell lines become methylated or remain unmethylated, depending on their positions in the viral genome. (ii) When Ad12 DNA or Ad12 DNA fragments are transfected into hamster cells and permanent cell lines are established by selection for the cotransfected neomycin phosphotransferase gene, patterns of de novo methylation in terminally or internally located segments of Ad12 DNA are different from those in Ad12-induced tumor cell lines. (iii) A detailed study on the topology of the integrated viral genomes in the Ad12-transformed hamster cell lines T637 and A2497-3 and in the Ad12-induced hamster tumors T191, T1111(1), and T181 has been performed. Some of the integrated viral genomes are inserted into the cellular genome in an orientation colinear with the virion genome; others have been rearranged. An originally internally located Ad12 DNA segment has become transposed to the left-terminal sequences of the viral genome in several cell lines and tumors. In the complete Ad12 genomes, the internally located PstI-D fragment becomes extensively methylated at the 5'-CCGG-3' and 5'-GCGC-3' sequences. When this DNA segment has been juxtaposed to the left-terminal, hypomethylated fragment of Ad12 DNA in rearranged genomes, the PstI-D fragment remains unmethylated. We therefore reason that the initiation of de novo methylation in integrated Ad12 DNA cannot be directed exclusively by the nucleotide sequence. Other parameters, such as site of integration, conformation of integrates, mode of cell selection, or chromatin structure related to transcriptional activity, may play decisive roles.
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Affiliation(s)
- G Orend
- Institute of Genetics, University of Cologne, Germany
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Affiliation(s)
- L A Lucher
- Department of Biological Sciences, Illinois State, University, Normal 61761, USA
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[11] Investigations on virus-host interactions: An abortive system. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/s1067-2389(06)80043-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Fechteler K, Tatzelt J, Huppertz S, Wilgenbus P, Doerfler W. The mechanism of adenovirus DNA integration: studies in a cell-free system. Curr Top Microbiol Immunol 1995; 199 ( Pt 2):109-37. [PMID: 7555065 DOI: 10.1007/978-3-642-79499-5_5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- K Fechteler
- Institut für Genetik, Cologne University, Germany
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Doerfler W. The insertion of foreign DNA into mammalian genomes and its consequences: a concept in oncogenesis. Adv Cancer Res 1995; 66:313-44. [PMID: 7793319 DOI: 10.1016/s0065-230x(08)60259-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- W Doerfler
- Institut für Genetik, Universität zu Köln, Germany
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Sprengel J, Schmitz B, Heuss-Neitzel D, Doerfler W. The complete nucleotide sequence of the DNA of human adenovirus type 12. Curr Top Microbiol Immunol 1995; 199 ( Pt 2):189-274. [PMID: 7555068 DOI: 10.1007/978-3-642-79499-5_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- J Sprengel
- Institut für Genetik, Universität zu Köln, Germany
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Schiedner G, Schmitz B, Doerfler W. Late transcripts of adenovirus type 12 DNA are not translated in hamster cells expressing the E1 region of adenovirus type 5. J Virol 1994; 68:5476-82. [PMID: 8057430 PMCID: PMC236948 DOI: 10.1128/jvi.68.9.5476-5482.1994] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Hamster cells are completely nonpermissive for the replication of human adenovirus type 12 (Ad12), whereas types 2 and 5 can replicate in hamster cells. The Ad5-transformed hamster cell line BHK297-C131, which carries the left terminal 18.7% of the Ad5 genome and expresses at least the viral E1A region, can somehow complement Ad12 DNA replication and the transcription of the late Ad12 genes. Since the interaction of Ad12 with hamster cells must constitute a significant factor in the induction of Ad12 tumors in neonatal hamsters, we have continued to examine details of this abortive virus infection. The late Ad12 mRNAs in BHK297-C131 cells are polyadenylated but are synthesized in reduced amounts compared with the Ad12 products in Ad12-infected human cells, which are permissive for viral replication. The late mRNA derived from the Ad12 fiber gene has been assessed for its structural properties. By cloning cDNA transcripts from this region and determining their nucleotide sequences, the authenticity of the complete Ad12 fiber sequence and the completeness of the Ad12-typical tripartite leader have been confirmed. Moreover, in Ad12-infected BHK297-C131 cells the Ad12 virus-associated RNA, a virus-encoded translational activator with the correct nucleotide sequence, is synthesized. Nevertheless, the synthesis of detectable amounts of Ad12 virion-specific proteins, and in particular that of the main viral antigens, hexons and fibers, cannot be documented. Cellular factors needed to promote late mRNA translation might be missing, or inhibitory factors might exist in Ad12-infected BHK297-C131 cells.
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Affiliation(s)
- G Schiedner
- Institut für Genetik, Universität zu Köln, Germany
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Karlin S, Doerfler W, Cardon LR. Why is CpG suppressed in the genomes of virtually all small eukaryotic viruses but not in those of large eukaryotic viruses? J Virol 1994; 68:2889-97. [PMID: 8151759 PMCID: PMC236777 DOI: 10.1128/jvi.68.5.2889-2897.1994] [Citation(s) in RCA: 250] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Dinucleotide over- and underrepresentation is evaluated in all available completely sequenced DNA or RNA viral genomes, ranging in size from 3 to 250 kb (available RNA viruses fall into the small-virus category). The dinucleotide CpG is statistically underrepresented (suppressed) in all but four of the small viruses (more than 75 with lengths of < 30 kb) but has normal relative abundances in most large viruses (> or = 30 kb). Most retrotransposons in eukaryotic species also show low CpG relative abundances. Interpretations, especially in some cases of DNA viruses or viruses with a DNA intermediate, might relate to methylation effects and modes of viral integration and excision. Other possible contributing factors relate to dinucleotide stacking energies, special mutation mechanisms, and evolutionary events.
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Affiliation(s)
- S Karlin
- Department of Mathematics, Stanford University, California 94305
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Sprengel J, Schmitz B, Heuss-Neitzel D, Zock C, Doerfler W. Nucleotide sequence of human adenovirus type 12 DNA: comparative functional analysis. J Virol 1994; 68:379-89. [PMID: 8254750 PMCID: PMC236298 DOI: 10.1128/jvi.68.1.379-389.1994] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A fresh inoculum of human adenovirus type 12 (Ad12) was obtained from the American Type Culture Collection and passaged once on human embryonic kidney cells, and Ad12 DNA was prepared from the first-passage yield to avoid higher passages which might have generated host-virus DNA recombinants. The 18 PstI fragments of Ad12 DNA were cloned into the pBluescript KS vector, and the entire nucleotide sequence of both strands from all 18 fragments was determined by using successive oligodeoxyribonucleotide primers. Ad12 DNA extends over 34,125 nucleotide pairs, and its molecular weight is calculated to be about 22 x 10(6). The nucleotide sequence of Ad12 DNA was subjected to computer analyses that determined possible open reading of frames on the two strands, the leader sequences, the position of the virus-associated RNA coding region, possible TATA, and polyadenylation signals. The distribution of the Ad12 open reading frames was similar to that in the previously sequenced Ad2 DNA, but there were also distinct differences. Ad12 DNA has an inverted terminal redundancy of 161 nucleotides, compared with 102 nucleotides in Ad2 DNA. There were stretches of sequence identity between Ad2 and Ad12 DNAs at both termini; the overall sequence similarity between the two viral genomes ranged between 59% (polypeptide IX) and 77% (in the E2 region), with high homology also in the sequences for the adenovirus DNA polymerase.
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Affiliation(s)
- J Sprengel
- Institute of Genetics, University of Cologne, Germany
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Zock C, Iselt A, Doerfler W. A unique mitigator sequence determines the species specificity of the major late promoter in adenovirus type 12 DNA. J Virol 1993; 67:682-93. [PMID: 8419643 PMCID: PMC237419 DOI: 10.1128/jvi.67.2.682-693.1993] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Human adenovirus type 12 (Ad12) cannot replicate in hamster cells, whereas human cells are permissive for Ad12. Ad12 DNA replication and late-gene and virus-associated RNA expression are blocked in hamster cells. Early Ad12 genes are transcribed, and the viral DNA can be integrated into the host genome. Ad12 DNA replication and late-gene transcription can be complemented in hamster cells by E1 functions of Ad2 or Ad5, for which hamster cells are fully permissive (for a review, see W. Doerfler, Adv. Virus Res. 39:89-128, 1991). We have previously demonstrated that a 33-nucleotide mitigator sequence, which is located in the downstream region of the major late promoter (MLP) of Ad12 DNA, is responsible for the inactivity of the Ad12 MLP in hamster cells (C. Zock and W. Doerfler, EMBO J. 9:1615-1623, 1990). A similar negative regulator has not been found in the MLP of Ad2 DNA. We have now studied the mechanism of action of this mitigator element. The results of nuclear run-on experiments document the absence of MLP transcripts in the nuclei of Ad12-infected BHK21 hamster cells. Surprisingly, the mitigator element cannot elicit its function in in vitro transcription experiments with nuclear extracts from both hamster BHK21 and human HeLa cells. Intact nuclear topology and/or tightly bound nuclear elements that cannot be eluted in nuclear extracts are somehow required for recognition of the Ad12 mitigator. Electrophoretic mobility shift assays have not revealed significant differences in the binding of proteins from human HeLa or hamster BHK21 cells to the mitigator sequence in the MLP of Ad12 DNA or to the corresponding sequence in Ad2 DNA. We have converted the sequence of the mitigator in the MLP of Ad12 DNA to the equivalent sequence in the MLP of Ad2 DNA by site-directed mutagenesis. This construct was not active in hamster cells. When the Ad12 mitigator, on the other hand, was inserted into the Ad2 MLP, the latter's function in hamster cells was not compromised. Deletions in the 5' upstream region of the Ad12 MLP have provided evidence for the existence of additional sequences that codetermine the deficiency of the Ad12 MLP in hamster cells. The amphifunctional YY1 protein from HeLa cells can bind specifically to the mitigator and to upstream elements of the MLP of Ad12 DNA.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- C Zock
- Institute for Genetics, University of Cologne, Germany
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Doerfler W. Adenoviral DNA integration and changes in DNA methylation patterns: a different view of insertional mutagenesis. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1993; 46:1-36. [PMID: 8234781 DOI: 10.1016/s0079-6603(08)61016-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- W Doerfler
- Institut für Genetik, Universität zu Köln, Germany
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Doerfler W. Patterns of de novo DNA methylation and promoter inhibition: studies on the adenovirus and the human genomes. EXS 1993; 64:262-99. [PMID: 8418951 DOI: 10.1007/978-3-0348-9118-9_12] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- W Doerfler
- Institut für Genetik, Universität zu Köln, Germany
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Affiliation(s)
- W Doerfler
- Institut für Genetik, Universität zu Köln, Germany
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