scholarly journals Interaction with CBP/p300 enables the bovine papillomavirus type 1 E6 oncoprotein to downregulate CBP/p300-mediated transactivation by p53

2000 ◽  
Vol 81 (11) ◽  
pp. 2617-2623 ◽  
Author(s):  
Holger Zimmermann ◽  
Choon-Heng Koh ◽  
Roland Degenkolbe ◽  
Mark J. O’Connor ◽  
Andreas Müller ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Cell Transformation ◽  
Human Papillomaviruses ◽  
Bovine Papillomavirus ◽  
Transcriptional Coactivator ◽  
Binding Properties ◽  
E6 Oncoprotein ◽  
P300 Binding ◽  
E6 Protein

The E6 oncoprotein of bovine papillomavirus type 1 (BPV-1) can transform cells independently of p53 degradation. The precise mechanisms underlying this transformation are not yet completely understood. Here it is shown that BPV-1 E6 interacts with CBP/p300 in the same way as described for the E6 proteins of oncogenic human papillomaviruses. This interaction results in an inhibition of the transcriptional coactivator function of CBP/p300 required by p53 and probably by other transcription factors. The comparison of the CBP/p300-binding properties of BPV-1 E6 mutants previously characterized in transcription and transformation studies suggests (i) that the E6–CBP/p300 interaction may be necessary, but not sufficient, for cell transformation, and (ii) that the transcriptional activator function, inherent to the E6 protein, is not derived from forming a complex with CBP/p300.

Selective enhancement of bovine papillomavirus type 1 DNA replication in Xenopus laevis eggs by the E6 gene product

1989 ◽  
Vol 9 (2) ◽  
pp. 406-414
Author(s):  
H Romanczuk ◽  
W M Wormington
Keyword(s):  
Dna Replication ◽  
Xenopus Laevis ◽  
Gene Product ◽  
Mammalian Cells ◽  
Xenopus Laevis Oocytes ◽  
Bovine Papillomavirus ◽  
In Vitro Synthesis ◽  
E6 Gene ◽  
E6 Protein

Genetic analyses of bovine papillomavirus type 1 (BPV-1) DNA in transformed mammalian cells have indicated that the E6 gene product is essential for the establishment and maintenance of a high plasmid copy number. In order to analyze the direct effect of the E6 protein on the replication of a BPV-1-derived plasmid, a cDNA containing the BPV-1 E6 open reading frame was subcloned into an SP6 vector for the in vitro synthesis of the corresponding mRNA. The SP6 E6 mRNA was injected into Xenopus laevis oocytes to determine the subcellular localization of the E6 gene product and to analyze the effect of the protein on BPV-1 DNA replication. SP6 E6 mRNA microinjected into stage VI oocytes was translated into a 15.5-kilodalton protein that was specifically immunoprecipitated by antibodies directed against the E6 gene product. The E6 protein preferentially accumulated in oocyte nuclei, a localization which is consistent with the replicative functions in which it has been implicated. The expression of E6 in replication-competent mature oocytes selectively enhanced the replication of a BPV-derived plasmid, indicating a direct role for this gene product in the control of BPV-1 DNA replication.

scholarly journals Early promoters of genital and cutaneous human papillomaviruses are differentially regulated by the bovine papillomavirus type 1 E2 gene product

1992 ◽  
Vol 73 (6) ◽  
pp. 1395-1400 ◽  
Author(s):  
M. C. Guido ◽  
R. Zamorano ◽  
E. Garrido-Guerrero ◽  
P. Gariglio ◽  
A. Garcia-Carranca
Keyword(s):  
Gene Product ◽  
Human Papillomaviruses ◽  
Bovine Papillomavirus ◽  
E2 Gene

scholarly journals Adenovirus Type 5 E1A and E6 Proteins of Low-Risk Cutaneous Beta-Human Papillomaviruses Suppress Cell Transformation through Interaction with FOXK1/K2 Transcription Factors

2010 ◽  
Vol 84 (6) ◽  
pp. 2719-2731 ◽  
Author(s):  
Jessica Komorek ◽  
Mohan Kuppuswamy ◽  
T. Subramanian ◽  
S. Vijayalingam ◽  
Elena Lomonosova ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Transcription Factors ◽  
Cell Transformation ◽  
Protein Complexes ◽  
Cellular Protein ◽  
Human Papillomaviruses ◽  
Terminal Region ◽  
Oncogenic Transformation ◽  
Exon 2 ◽  
C Terminus

ABSTRACT The adenovirus (Adv) oncoprotein E1A stimulates cell proliferation and inhibits differentiation. These activities are primarily linked to the N-terminal region (exon 1) of E1A, which interacts with multiple cellular protein complexes. The C terminus (exon 2) of E1A antagonizes these processes, mediated in part through interaction with C-terminal binding proteins 1 and 2 (CtBP1/2). To identify additional cellular E1A targets that are involved in the modulation of E1A C-terminus-mediated activities, we undertook tandem affinity purification of E1A-associated proteins. Through mass spectrometric analysis, we identified several known E1A-interacting proteins as well as novel E1A targets, such as the forkhead transcription factors, FOXK1/K2. We identified a Ser/Thr-containing sequence motif in E1A that mediated interaction with FOXK1/K2. We demonstrated that the E6 proteins of two beta-human papillomaviruses (HPV14 and HPV21) associated with epidermodysplasia verruciformis also interacted with FOXK1/K2 through a motif similar to that of E1A. The E1A mutants deficient in interaction with FOXK1/K2 induced enhanced cell proliferation and oncogenic transformation. The hypertransforming activity of the mutant E1A was suppressed by HPV21 E6. An E1A-E6 chimeric protein containing the Ser/Thr domain of the E6 protein in E1A interacted efficiently with FOXK1/K2 and inhibited cell transformation. Our results suggest that targeting FOXK1/K2 may be a common mechanism for certain beta-HPVs and Adv5. E1A exon 2 mutants deficient in interaction with the dual-specificity kinases DYRK1A/1B and their cofactor HAN11 also induced increased cell proliferation and transformation. Our results suggest that the E1A C-terminal region may suppress cell proliferation and oncogenic transformation through interaction with three different cellular protein complexes: FOXK1/K2, DYRK(1A/1B)/HAN11, and CtBP1/2.

scholarly journals The E6 Oncoproteins of High-Risk Papillomaviruses Bind to a Novel Putative GAP Protein, E6TP1, and Target It for Degradation

1999 ◽  
Vol 19 (1) ◽  
pp. 733-744 ◽  
Author(s):  
Qingshen Gao ◽  
Seetha Srinivasan ◽  
Sarah N. Boyer ◽  
David E. Wazer ◽  
Vimla Band
Keyword(s):  
High Risk ◽  
P53 Protein ◽  
Single Gene ◽  
Human Papillomaviruses ◽  
Dominant Negative ◽  
Hpv16 E6 ◽  
Hpv E6 ◽  
E6 Oncoprotein ◽  
E6 Protein

ABSTRACT The high-risk human papillomaviruses (HPVs) are associated with carcinomas of the cervix and other genital tumors. Previous studies have identified two viral oncoproteins, E6 and E7, which are expressed in the majority of HPV-associated carcinomas. The ability of high-risk HPV E6 protein to immortalize human mammary epithelial cells (MECs) has provided a single-gene model to study the mechanisms of E6-induced oncogenic transformation. In this system, the E6 protein targets the p53 tumor suppressor protein for degradation, and mutational analyses have shown that E6-induced degradation of p53 protein is required for MEC immortalization. However, the inability of most dominant-negative p53 mutants to induce efficient immortalization of MECs suggests the existence of additional targets of the HPV E6 oncoprotein. Using the yeast two-hybrid system, we have isolated a novel E6-binding protein. This polypeptide, designated E6TP1 (E6-targeted protein 1), exhibits high homology to GTPase-activating proteins for Rap, including SPA-1, tuberin, and Rap1GAP. The mRNA for E6TP1 is widely expressed in tissues and in vitro-cultured cell lines. The gene for E6TP1 localizes to chromosome 14q23.2-14q24.3 within a locus that has been shown to undergo loss of heterozygosity in malignant meningiomas. Importantly, E6TP1 is targeted for degradation by the high-risk but not the low-risk HPV E6 proteins both in vitro and in vivo. Furthermore, the immortalization-competent but not the immortalization-incompetent HPV16 E6 mutants target the E6TP1 protein for degradation. Our results identify a novel target for the E6 oncoprotein and provide a potential link between HPV E6 oncogenesis and alteration of a small G protein signaling pathway.

scholarly journals Mutagenic Potential ofBos taurusPapillomavirus Type 1 E6 Recombinant Protein: First Description

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Rodrigo Pinheiro Araldi ◽  
Jacqueline Mazzuchelli-de-Souza ◽  
Diego Grando Modolo ◽  
Edislane Barreiros de Souza ◽  
Thatiana Corrêa de Melo ◽  
...  
Keyword(s):  
Bos Taurus ◽  
Micronucleus Assay ◽  
Positive Control ◽  
Bovine Papillomavirus ◽  
Mutagenic Potential ◽  
E6 Oncoprotein ◽  
Per Se ◽  
E6 And E7 ◽  
Negative Controls

Bovine papillomavirus (BPV) is considered a useful model to study HPV oncogenic process. BPV interacts with the host chromatin, resulting in DNA damage, which is attributed to E5, E6, and E7 viral oncoproteins activity. However, the oncogenic mechanisms of BPV E6 oncoproteinper seremain unknown. This study aimed to evaluate the mutagenic potential ofBos tauruspapillomavirus type 1 (BPV-1) E6 recombinant oncoprotein by the cytokinesis-block micronucleus assay (CBMNA) and comet assay (CA). Peripheral blood samples of five calves were collected. Samples were subjected to molecular diagnosis, which did not reveal presence of BPV sequences. Samples were treated with 1 μg/mL of BPV-1 E6 oncoprotein and 50 μg/mL of cyclophosphamide (positive control). Negative controls were not submitted to any treatment. The samples were submitted to the CBMNA and CA. The results showed that BPV E6 oncoprotein induces clastogenesisper se, which is indicative of genomic instability. These results allowed better understanding the mechanism of cancer promotion associated with the BPV E6 oncoprotein and revealed that this oncoprotein can induce carcinogenesisper se. E6 recombinant oncoprotein has been suggested as a possible vaccine candidate. Results pointed out that BPV E6 recombinant oncoprotein modifications are required to use it as vaccine.

scholarly journals The E6 Protein of the Cutaneous Human Papillomavirus Type 8 Can Stimulate the Viral Early and Late Promoters by Distinct Mechanisms

2006 ◽  
Vol 80 (17) ◽  
pp. 8718-8728 ◽  
Author(s):  
Andreas Müller-Schiffmann ◽  
Julia Beckmann ◽  
Gertrud Steger
Keyword(s):  
Gene Expression ◽  
Direct Interaction ◽  
Human Papillomaviruses ◽  
Late Promoter ◽  
Rnase Protection ◽  
Early Promoter ◽  
E6 Oncoprotein ◽  
E6 Protein ◽  
First Time ◽  
Amino Acid Segment

ABSTRACT The expression of the proteins encoded by human papillomaviruses (HPVs) is tightly linked to the differentiation program of the infected keratinocytes. The late promoter, expressing the structural proteins, becomes activated in the differentiated keratinocytes, while the early promoter is also active in the basal layers. We have shown previously that the viral transcriptional regulator E2 and the cellular coactivator p300 cooperate in activation of gene expression of HPV8, which infects the skin and is associated with epidermodysplasia verruciformis. Here we demonstrate that this activation is further stimulated after overexpression of the E6 oncoprotein of HPV8 (8E6). RNase protection experiments revealed that 8E6 efficiently cooperates with 8E2 and p300 in activation of the late promoter. In addition, the early promoter, which did not respond to 8E2 and/or p300, was stimulated more than fourfold by 8E6. Our data suggest that both promoters are activated via distinct mechanisms, since the activation of the early promoter was achieved by the N-terminal moiety of 8E6; in contrast, its C-terminal half was sufficient for late promoter activation. This was markedly reduced by the deletion of amino acids 132 to 136 of 8E6, which also abolished the binding to p300, indicating that a direct interaction between 8E6 and p300 is involved. Moreover, a 45-amino-acid segment within the C/H3 region of p300 is required for 8E6 to stimulate the coactivator function of p300. Our results demonstrate for the first time that an E6 oncoprotein of HPV directly contributes to the regulation of HPV gene expression.

scholarly journals Expression andIn SilicoAnalysis of the Recombinant Bovine Papillomavirus E6 Protein as a Model for Viral Oncoproteins Studies

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
J. Mazzuchelli-de-Souza ◽  
R. F. Carvalho ◽  
R. M. Ruiz ◽  
T. C. Melo ◽  
R. P. Araldi ◽  
...  
Keyword(s):  
Recombinant Proteins ◽  
In Silico ◽  
Cell Transformation ◽  
Bovine Papillomavirus ◽  
Viral Oncoprotein ◽  
Viral Oncoproteins ◽  
Biotechnological Products ◽  
Clone And Express ◽  
E6 Protein

Bovine papillomaviruses (BPVs) are recognized as the causal agents of economical relevant diseases in cattle, associated with the development of tumors in skin and mucosa. The oncogenesis process is mainly associated with different viral oncoprotein expressions, which are involved in cell transformation. The expression and characterization of recombinant viral oncoproteins represent an attractive strategy to obtain biotechnological products as antibodies and potential vaccines, Thus, the aim of this work was to clone and express the BPV-1 and BPV-2 E6 recombinant proteins and performin silicoanalysis in order to develop a strategy for the systematic study of other papillomaviruses oncoproteins. The results demonstrated that BPV-1 and BPV-2 E6 recombinant proteins were expressed and purified from bacterial system as well as itsin silicoanalysis was performed in order to explore and predict biological characteristics of these proteins.

scholarly journals Identification of Poly(ADP-Ribose) Polymerase as a Transcriptional Coactivator of the Human T-Cell Leukemia Virus Type 1 Tax Protein

2000 ◽  
Vol 74 (5) ◽  
pp. 2169-2177 ◽  
Author(s):  
Mark G. Anderson ◽  
Kirsten E. S. Scoggin ◽  
Cynthia M. Simbulan-Rosenthal ◽  
Jennifer A. Steadman
Keyword(s):  
Transcription Factors ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Leukemia Virus ◽  
Transcriptional Coactivator ◽  
Cell Leukemia Virus Type ◽  
General Transcription Factors ◽  
Human T Cell ◽  
T Cell Leukemia Virus

ABSTRACT Human T-cell leukemia virus type 1 (HTLV-1) encodes a transcriptional activator, Tax, whose activity is believed to contribute significantly to cellular transformation. Tax stimulates transcription from the proviral promoter as well as from promoters for a variety of cellular genes. The mechanism through which Tax communicates to the general transcription factors and RNA polymerase II has not been completely determined. We investigated whether Tax could function directly through the general transcription factors and RNA polymerase II or if other intermediary factors or coactivators were required. Our results show that a system consisting of purified recombinant TFIIA, TFIIB, TFIIE, TFIIF, CREB, and Tax, along with highly purified RNA polymerase II, affinity-purified epitope-tagged TFIID, and semipurified TFIIH, supports basal transcription of the HTLV-1 promoter but is not responsive to Tax. Two additional activities were required for Tax to stimulate transcription. We demonstrate that one of these activities is poly(ADP-ribose) polymerase (PARP), a molecule that has been previously identified to be the transcriptional coactivator PC1. PARP functions as a coactivator in our assays at molar concentrations approximately equal to those of the DNA and equal to or less than those of the transcription factors in the assay. We further demonstrate that PARP stimulates Tax-activated transcription in vivo, demonstrating that this biochemical approach has functionally identified a novel target for the retroviral transcriptional activator Tax.

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