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Michele Carbone - One of the best experts on this subject based on the ideXlab platform.

  • progressive aberrant methylation of the rassf1a gene in Simian Virus 40 infected human mesothelial cells
    Oncogene, 2002
    Co-Authors: Shinichi Toyooka, Maurizio Bocchetta, Michele Carbone, Kiyomi O Toyooka, Narayan Shivapurkar, John D Minna, Adi F Gazdar
    Abstract:

    Progressive aberrant methylation of the RASSF1A gene in Simian Virus 40 infected human mesothelial cells

  • Human mesothelial cells are unusually susceptible to Simian Virus 40-mediated transformation and asbestos cocarcinogenicity
    Proceedings of the National Academy of Sciences of the United States of America, 2000
    Co-Authors: Maurizio Bocchetta, Ilaria Di Resta, Amy Powers, Raoul Fresco, Alessandra Tosolini, Joseph R. Testa, Paola Rizzo, Harvey I. Pass, Michele Carbone
    Abstract:

    Mesothelioma, a malignancy associated with asbestos, has been recently linked to Simian Virus 40 (SV40). We found that infection of human mesothelial cells by SV40 is very different from the semipermissive infection thought to be characteristic of human cells. Mesothelial cells are uniformly infected but not lysed by SV40, a mechanism related to p53, and undergo cell transformation at an extremely high rate. Exposure of mesothelial cells to asbestos complemented SV40 mutants in transformation. Our data provide a mechanistic explanation for the ability of SV40 to transform mesothelial cells preferentially and indicate that asbestos and SV40 may be cocarcinogens.

  • human mesotheliomas contain the Simian Virus 40 regulatory region and large tumor antigen dna sequences
    The Journal of Thoracic and Cardiovascular Surgery, 1998
    Co-Authors: Jessica S Donington, Paola Rizzo, Harvey I. Pass, Michael Nishimura, Ronald C Kennedy, Michele Carbone
    Abstract:

    Abstract Background: A cohort (20%) of patients with mesothelioma will not have an exposure to asbestos. Recently, a DNA tumor Virus (Simian Virus 40) has been shown to cause hamster mesotheliomas; we previously described Simian Virus 40–like DNA amino terminus sequences in 29 of 48 mesotheliomas. We analyzed an additional 42 mesotheliomas to determine (1) whether our initial observations were durable and (2) the extent to which the Simian Virus 40 genome is present in mesotheliomas. Methods: Genomic DNA was extracted from snap frozen mesothelioma tumor samples and from the Simian Virus 40–induced hamster mesothelioma tumor H9A. Polymerase chain reaction primers were used to amplify various Simian Virus 40 large T-antigen regions including a 105–base pair amino terminus fragment, a 281–base pair carboxyl terminus fragment, and a 310–base pair fragment of the enhancer promoter region. Endonuclease digestions and Southern blotting were used to verify the expected product. Results: Thirty of the 42 (71%) samples amplified T-antigen amino sequences, and specificity was verified by Southern hybridization. Sixteen of 42 samples (38%) amplified the appropriate size fragment for the carboxyl terminus, and digestion with BsaB1 matched that of H9A. Twenty-two of 42 samples (52%) amplified Simian Virus 40 regulatory sequences and Fok 1 digestion matched that of the hamster control tumor. Sequence analysis (4 patients) revealed 100% homology with the regulatory region of Simian Virus 40 strain 776. Conclusions: These data suggest an association between the Simian Virus 40 Virus and human mesothelioma that could be exploited for diagnostic/therapeutic options including early detection and potential vaccination strategies. (J Thorac Cardiovasc Surg 1998;116:854-9)

  • Simian Virus 40 large t antigen binds p53 in human mesotheliomas
    Nature Medicine, 1997
    Co-Authors: Michele Carbone, Paola Rizzo, Daphne J Y Mew, Antonio Procopio, Philip M Grimley, Viji Shridhar, Andrea De Bartolomeis, V Esposito, Maria Teresa Giuliano, Seth M Steinberg
    Abstract:

    We found that Simian Virus 40 (SV40) induces mesotheliomas in hamsters and that 60% of human mesotheliomas contain and express SV40 sequences, results now confirmed by others [ref. 3-5, and presentations by D. Griffiths & R. Weiss, F. Galateau-SallE, and H.I.P. at "Simian Virus 40: A possible human polyoma Virus," NIH workshop, 27-28 January 1997, Bethesda, MD (transcript available through SAG Corp., Washington, DC 20008)]. Mesothelioma, an aggressive malignancy resistant to therapy, originates from the serosal lining of the pleural, pericardial and peritoneal cavities. The incidence of mesothelioma continues to increase worldwide because of exposure to crocidolite asbestos. However, at least 20% of mesotheliomas in the United States are not associated with asbestos exposure, and only a minority of people exposed to high concentrations of asbestos develop mesothelioma. Thus, other carcinogens may induce mesothelioma in individuals not exposed to asbestos, and/or may render particular individuals more susceptible to the carcinogenic effect of asbestos. We investigated whether the expression of the SV40 large T-antigen (Tag) interferes with the normal expression of the tumor suppressor gene p53 in human mesotheliomas. We found that SV40 Tag retains its ability to bind and to inactivate p53, a cellular protein that when normally expressed plays an important role in suppressing tumor growth and in inducing sensitivity to therapy. Our findings do not establish a cause-and-effect relation, but indicate that the possibility that SV40 contributes to the development of human mesotheliomas should be carefully investigated.

  • Simian Virus 40 like dna sequences in human pleural mesothelioma
    Oncogene, 1994
    Co-Authors: Harvey I. Pass, Michele Carbone, Paola Rizzo, M Marinetti, M Di Muzio, Daphne J Y Mew, Arthur S Levine, Antonio Procopio
    Abstract:

    Mesotheliomas are pleural, pericardial, or peritoneal neoplasms frequently associated with asbestos exposure, and it is estimated that over the next twenty years up to 80,000 new cases are expected in the USA alone. We found Simian Virus 40-like DNA sequences in 29 of 48 mesotheliomas studied (60%) and demonstrated Simian Virus large-T antigen expression in 13 of 16 specimens. The matching lung samples did not contain Simian Virus 40-like sequences; however, they contained asbestos. These findings are to our knowledge the first demonstration of a physical link between DNA Virus-like sequences and human mesothelioma. We suggest that a Simian Virus 40-like Virus may act independently or as a co-carcinogen with asbestos. Moreover, the selective large T antigen expression by mesothelioma and not by the surrounding pulmonary parenchyma may have both diagnostic and therapeutic implications.

Susan Swift - One of the best experts on this subject based on the ideXlab platform.

  • the tsa58 Simian Virus 40 large tumor antigen disrupts megakaryocyte differentiation in transgenic mice
    Proceedings of the National Academy of Sciences of the United States of America, 1994
    Co-Authors: Murray O Robinson, Chris J M Saris, W Zhou, Martha Hokom, Dimitry M Danilenko, R E Atherton, Wl Xu, Sharon Mu, Susan Swift
    Abstract:

    Abstract Thrombocytopenia is a condition of multiple etiologies affecting the megakaryocyte lineage. To perturb this lineage in transgenic mice, the tsA58 mutation of the Simian Virus 40 large tumor antigen was targeted to megakaryocytes using the platelet factor 4 promoter. Ten of 17 transgenic lines generated exhibited low platelet levels, each line displaying a distinct, heritable level of thrombocytopenia. Within a line, the degree of the platelet reduction correlated directly with transgene zygosity. The platelet level could be further reduced by the inactivation of one copy of the endogenous retinoblastoma gene. Western blot analysis detected large tumor antigen protein in the most severely affected lines; less affected lines were below the level of detection. Platelets and megakaryocytes from thrombocytopenic mice exhibited morphological abnormalities. Mice with either normal or reduced platelet levels developed megakaryocytic malignancies with a mean age of onset of about 8 months. There was no correlation between severity of thrombocytopenia and onset of malignancy. These mice provide a defined genetic model for thrombocytopenia, and for megakaryocytic neoplasia, and implicate the retinoblastoma protein in the process of megakaryocyte differentiation.

James A Decaprio - One of the best experts on this subject based on the ideXlab platform.

  • Cellular transformation by Simian Virus 40 and Murine Polyoma Virus T antigens
    Seminars in cancer biology, 2009
    Co-Authors: Jingwei Cheng, James A Decaprio, Michele M. Fluck, Brian Schaffhausen
    Abstract:

    Simian Virus 40 (SV40) and Mouse Polyoma Virus (PY) are small DNA tumor Viruses that have been used extensively to study cellular transformation. The SV40 early region encodes three tumor antigens, large T (LT), small T (ST) and 17KT that contribute to cellular transformation. While PY also encodes LT and ST, the unique middle T (MT) generates most of the transforming activity. SV40 LT mediated transformation requires binding to the tumor suppressor proteins Rb and p53 in the nucleus and ST binding to the protein phosphatase PP2A in the cytoplasm. SV40 LT also binds to several additional cellular proteins including p300, CBP, Cul7, IRS1, Bub1, Nbs1 and Fbxw7 that contribute to viral transformation. PY MT transformation is dependent on binding to PP2A and the Src family protein tyrosine kinases (PTK) and assembly of a signaling complex on cell membranes that leads to transformation in a manner similar to Her2/neu. Phosphorylation of MT tyrosine residues activates key signaling molecules including Shc/Grb2, PI3K and PLCgamma1. The unique contributions of SV40 LT and ST and PY MT to cellular transformation have provided significant insights into our understanding of tumor suppressors, oncogenes and the process of oncogenesis.

  • inhibition of Simian Virus 40 large t antigen helicase activity by fluoroquinolones
    Antiviral Therapy, 2007
    Co-Authors: Syed Ali, Anil Chandraker, James A Decaprio
    Abstract:

    Background: Fluoroquinolones represent a potent group of antibiotics that inhibit bacterial DNA replication by targeting the essential bacterial enzymes gyrase and topoisomerase IV. Inhibition of gyrase activity by quinolones involves the interaction of these drugs with the helicase component of bacterial gyrase. DNA tumour Viruses also encode helicases that are essential for their DNA replication in the host. Methods: In this study we have evaluated the effect of fluoroquinolones on viral DNA replication using the DNA tumour Virus Simian Virus 40 (SV40) as our model. Four different fluoroquinolones, namely, levofloxacin, trovafloxacin, ciprofloxacin and ofloxacin, were tested for their ability to inhibit viral DNA replication. Results: We show here that all four quinolones tested were effective in the inhibition of SV40 plaque formation and DNA replication in CV1-P cells. In addition, we found that each of these quinolones was inhibitory to the helicase activity of SV40 large tumour antigen. Conclusions: Fluoroquinolones and their derivates may therefore be useful in the treatment and/or prevention of infection by SV40-homologous human DNA Viruses that encode helicase activity for their survival.

  • p53 targets Simian Virus 40 large t antigen for acetylation by cbp
    Journal of Virology, 2004
    Co-Authors: Danielle L Poulin, Andrew L Kung, James A Decaprio
    Abstract:

    Simian Virus 40 (SV40) large T antigen (T Ag) interacts with the tumor suppressor p53 and the transcriptional coactivators CBP and p300. Binding of these cellular proteins in a ternary complex has been implicated in T Ag-mediated transformation. It has been suggested that the ability of CBP/p300 to modulate p53 function underlies p53's regulation of cell proliferation and tumorigenesis. In this study, we provide further evidence that CBP activity may be mediated through its synergistic action with p53. We demonstrate that SV40 T Ag is acetylated in vivo in a p53-dependent manner and T Ag acetylation is largely mediated by CBP. The acetylation of T Ag is dependent on its interaction with p53 and on p53's interaction with CBP. We have mapped the site of acetylation on T Ag to the C-terminal lysine residue 697. This acetylation site is conserved between the T antigens of the human polyomaViruses JC and BK, which are also known to interact with p53. We show that both JC and BK T antigens are also acetylated at corresponding sites in vivo. While other proteins are known to be acetylated by CBP/p300, none are known to depend on p53 for acetylation. T Ag acetylation may provide a regulatory mechanism for T Ag binding to a cellular factor or play a role in another aspect of T Ag function.

  • association of p300 and cbp with Simian Virus 40 large t antigen
    Molecular and Cellular Biology, 1996
    Co-Authors: Richard Eckner, James A Decaprio, John W Ludlow, Nancy L Lill, Elizabeth Oldread, Zoltan Arany, N Modjtahedi, David M Livingston, Jeffrey A Morgan
    Abstract:

    p300 and the CREB-binding protein CBP are two large nuclear phosphoproteins that are structurally highly related. Both function, in part, as transcriptional adapters and are targeted by the adenoVirus E1A oncoprotein. We show here that p300 and CBP interact with another transforming protein, the Simian Virus 40 large T antigen (T). This interaction depends on the integrity of a region of T which is critical for its transforming and mitogenic properties and includes its LXCXE Rb-binding motif. T interferes with normal p300 and CBP function on at least two different levels. The presence of T alters the phosphorylation states of both proteins and inhibits their transcriptional activities on certain promoters. Although E1A and T show little sequence similarity, they interact with the same domain of p300 and CBP, suggesting that this region exhibits considerable flexibility in accommodating diverse protein ligands.

Ari Helenius - One of the best experts on this subject based on the ideXlab platform.

  • role of endosomes in Simian Virus 40 entry and infection
    Journal of Virology, 2011
    Co-Authors: Sabrina Engel, Thomas Heger, Roberta Mancini, Fabian Herzog, Jiirgen Kartenbeck, Arnold Hayer, Ari Helenius
    Abstract:

    After binding to its cell surface receptor ganglioside GM1, Simian Virus 40 (SV40) is endocytosed by lipid raft-mediated endocytosis and slowly transported to the endoplasmic reticulum, where partial uncoating occurs. We analyzed the intracellular pathway taken by the Virus in HeLa and CV-1 cells by using a targeted small interfering RNA (siRNA) silencing screen, electron microscopy, and live-cell imaging as well as by testing a variety of cellular inhibitors and other perturbants. We found that the Virus entered early endosomes, late endosomes, and probably endolysosomes before reaching the endoplasmic reticulum and that this pathway was part of the infectious route. The Virus was especially sensitive to a variety of perturbations that inhibited endosome acidification and maturation. Contrary to our previous models, which postulated the passage of the Virus through caveolin-rich organelles that we called caveosomes, we conclude that SV40 depends on the classical endocytic pathway for infectious entry.

  • n glycolyl gm1 ganglioside as a receptor for Simian Virus 40
    Journal of Virology, 2007
    Co-Authors: Maria A Campanerorhodes, Alicia E Smith, Robert A Childs, Yibing Zhang, Helge Ewers, Laura Mauri, Sandro Sonnino, Wengang Chai, Ari Helenius, Anne Imberty
    Abstract:

    Carbohydrate microarrays have emerged as powerful tools in analyses of microbe-host interactions. Using a microarray with 190 sequence-defined oligosaccharides in the form of natural glycolipids and neoglycolipids representative of diverse mammalian glycans, we examined interactions of Simian Virus 40 (SV40) with potential carbohydrate receptors. While the results confirmed the high specificity of SV40 for the ganglioside GM1, they also revealed that N-glycolyl GM1 ganglioside [GM1(Gc)], which is characteristic of Simian species and many other nonhuman mammals, is a better ligand than the N-acetyl analog [GM1(Ac)] found in mammals, including humans. After supplementing glycolipid-deficient GM95 cells with GM1(Ac) and GM1(Gc) gangliosides and the corresponding neoglycolipids with phosphatidylethanolamine lipid groups, it was found that GM1(Gc) analogs conferred better Virus binding and infectivity. Moreover, we visualized the interaction of NeuGc with VP1 protein of SV40 by molecular modeling and identified a conformation for GM1(Gc) ganglioside in complex with the Virus VP1 pentamer that is compatible with its presentation as a membrane receptor. Our results open the way not only to detailed studies of SV40 infection in relation to receptor expression in host cells but also to the monitoring of changes that may occur with time in receptor usage by the Virus.

  • Simian Virus 40 depends on er protein folding and quality control factors for entry into host cells
    Cell, 2007
    Co-Authors: Mario Schelhaas, Lucas Pelkmans, Johan Malmstrom, Johannes Haugstetter, Lars Ellgaard, Kay Grunewald, Ari Helenius
    Abstract:

    Cell entry of Simian Virus 40 (SV40) involves caveolar/lipid raft-mediated endocytosis, vesicular transport to the endoplasmic reticulum (ER), translocation into the cytosol, and import into the nucleus. We analyzed the effects of ER-associated processes and factors on infection and on isolated Viruses and found that SV40 makes use of the thiol-disulfide oxidoreductases, ERp57 and PDI, as well as the retrotranslocation proteins Derlin-1 and Sel1L. ERp57 isomerizes specific interchain disulfides connecting the major capsid protein, VP1, to a crosslinked network of neighbors, thus uncoupling about 12 of 72 VP1 pentamers. Cryo-electron tomography indicated that loss of interchain disulfides coupled with calcium depletion induces selective dissociation of the 12 vertex pentamers, a step likely to mimic uncoating of the Virus in the cytosol. Thus, the Virus utilizes the protein folding machinery for initial uncoating before exploiting the ER-associated degradation machinery presumably to escape from the ER lumen into the cytosol.

  • clathrin and caveolin 1 independent endocytosis entry of Simian Virus 40 into cells devoid of caveolae
    Journal of Cell Biology, 2005
    Co-Authors: Evamaria Damm, Jürgen Kartenbeck, Lucas Pelkmans, Anna Mezzacasa, Teymuras V Kurzchalia, Ari Helenius
    Abstract:

    Simian Virus 40 (SV40) has been shown to enter host cells by caveolar endocytosis followed by transport via caveosomes to the endoplasmic reticulum (ER). Using a caveolin-1 (cav-1)–deficient cell line (human hepatoma 7) and embryonic fibroblasts from a cav-1 knockout mouse, we found that in the absence of caveolae, but also in wild-type embryonic fibroblasts, the Virus exploits an alternative, cav-1–independent pathway. Internalization was rapid (t1/2 = 20 min) and cholesterol and tyrosine kinase dependent but independent of clathrin, dynamin II, and ARF6. The Viruses were internalized in small, tight-fitting vesicles and transported to membrane-bounded, pH-neutral organelles similar to caveosomes but devoid of cav-1 and -2. The Viruses were next transferred by microtubule-dependent vesicular transport to the ER, a step that was required for infectivity. Our results revealed the existence of a Virus-activated endocytic pathway from the plasma membrane to the ER that involves neither clathrin nor caveolae and that can be activated also in the presence of cav-1.

  • Clathrin- and caveolin-1–independent endocytosis: entry of Simian Virus 40 into cells devoid of caveolae
    The Journal of cell biology, 2005
    Co-Authors: Evamaria Damm, Jürgen Kartenbeck, Lucas Pelkmans, Anna Mezzacasa, Teymuras V Kurzchalia, Ari Helenius
    Abstract:

    Simian Virus 40 (SV40) has been shown to enter host cells by caveolar endocytosis followed by transport via caveosomes to the endoplasmic reticulum (ER). Using a caveolin-1 (cav-1)–deficient cell line (human hepatoma 7) and embryonic fibroblasts from a cav-1 knockout mouse, we found that in the absence of caveolae, but also in wild-type embryonic fibroblasts, the Virus exploits an alternative, cav-1–independent pathway. Internalization was rapid (t1/2 = 20 min) and cholesterol and tyrosine kinase dependent but independent of clathrin, dynamin II, and ARF6. The Viruses were internalized in small, tight-fitting vesicles and transported to membrane-bounded, pH-neutral organelles similar to caveosomes but devoid of cav-1 and -2. The Viruses were next transferred by microtubule-dependent vesicular transport to the ER, a step that was required for infectivity. Our results revealed the existence of a Virus-activated endocytic pathway from the plasma membrane to the ER that involves neither clathrin nor caveolae and that can be activated also in the presence of cav-1.

Jose Maria Carazo - One of the best experts on this subject based on the ideXlab platform.

  • large t antigen on the Simian Virus 40 origin of replication a 3d snapshot prior to dna replication
    The EMBO Journal, 2003
    Co-Authors: Maria G Gomezlorenzo, Mikel Valle, Joachim Frank, Claudia Gruss, Carlos Oscar S. Sorzano, Xiaojiang S. Chen, Luis Enrique Donate, Jose Maria Carazo
    Abstract:

    Large T antigen is the replicative helicase of Simian Virus 40. Its specific binding to the origin of replication and oligomerization into a double hexamer distorts and unwinds dsDNA. In viral replication, T antigen acts as a functional homolog of the eukaryotic minichromosome maintenance factor MCM. T antigen is also an oncoprotein involved in transformation through interaction with p53 and pRb. We obtained the three‐dimensional structure of the full‐length T antigen double hexamer assembled at its origin of replication by cryoelectron microscopy and single‐particle reconstruction techniques. The double hexamer shows different degrees of bending along the DNA axis. The two hexamers are differentiated entities rotated relative to each other. Isolated strands of density, putatively assigned to ssDNA, protrude from the hexamer–hexamer junction mainly at two opposite sites. The structure of the T antigen at the origin of replication can be understood as a snapshot of the dynamic events leading to DNA unwinding. Based on these results a model for the initiation of Simian Virus 40 DNA replication is proposed.

  • Large T Antigen on the Simian Virus 40 Origin . . .
    2003
    Co-Authors: Maria G. Gomez-lorenzo, Mikel Valle, Joachim Frank, Claudia Gruss, Carlos Oscar S. Sorzano, Xiaojiang S. Chen, Luis Enrique Donate, Jose Maria Carazo
    Abstract:

    these results a model for the initiation of Simian Virus 40 DNA replication is proposed. ########: cryoelectron microscopy/DNA replication/ helicases/large T antigen/SV40 Introduction Large T antigen (Tag) of Simian Virus 40 (SV40) is a multifunctional protein involved in several processes that eventually lead to the replication of the Virus inside eukaryotic cells. Among its functions Tag has the ability to interfere with key cellular regulatory pathways resulting in the deregulation of the cell cycle and tumorogenesis in part by blocking p53 and the retinoblastoma protein (pRB) function (Simmons, 2000). SV40 has been extensively used as a model system for the study of replication in eukaryotes for two main reasons. First, the origin of replication for SV40 genome, unlike that of the eukaryotic cells, is very well characterized and is specically recognized by Tag. Secondly, the host cell provides all the other components necessary to form the primosome for initiating DNA replica