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Joe S. Mymryk - One of the best experts on this subject based on the ideXlab platform.
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inhibition of human adenovirus replication by the importin α β1 nuclear import inhibitor ivermectin
Journal of Virology, 2020Co-Authors: Cason R King, Joe S. Mymryk, Mackenzie J Dodge, Tanner M Tessier, Jason B WeinbergAbstract:Human adenoviruses (HAdV) are ubiquitous within the human population and comprise a significant burden of respiratory illnesses worldwide. Pediatric and immunocompromised individuals are at particular risk for developing severe disease; however, no approved antiviral therapies specific to HAdV exist. Ivermectin is an FDA-approved broad-spectrum antiparasitic drug that also exhibits antiviral properties against a diverse range of viruses. Its proposed function is inhibiting the classical Protein nuclear import pathway mediated by importin-α (Imp-α) and -β1 (Imp-β1). Many viruses, including HAdV, rely on this host pathway for transport of viral Proteins across the nuclear envelope. In this study, we show that ivermectin inhibits HAdV-C5 early gene transcription, early and late Protein expression, genome replication, and production of infectious viral progeny. Similarly, ivermectin inhibits genome replication of HAdV-B3, a clinically important pathogen responsible for numerous recent outbreaks. Mechanistically, we show that ivermectin disrupts binding of the viral E1A Protein to Imp-α without affecting the interaction between Imp-α and Imp-β1. Our results further extend ivermectin's broad antiviral activity and provide a mechanistic underpinning for its mode of action as an inhibitor of cellular Imp-α/β1-mediated nuclear import.IMPORTANCE Human adenoviruses (HAdVs) represent a ubiquitous and clinically important pathogen without an effective antiviral treatment. HAdV infections typically cause mild symptoms; however, individuals such as children, those with underlying conditions, and those with compromised immune systems can develop severe disseminated disease. Our results demonstrate that ivermectin, an FDA-approved antiparasitic agent, is effective at inhibiting replication of several HAdV types in vitro This is in agreement with the growing body of literature suggesting ivermectin has broad antiviral activity. This study expands our mechanistic knowledge of ivermectin by showing that ivermectin targets the ability of importin-α (Imp-α) to recognize nuclear localization sequences, without effecting the Imp-α/β1 interaction. These data also exemplify the applicability of targeting host factors upon which viruses rely as a viable antiviral strategy.
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differential effects of human adenovirus E1A Protein isoforms on aerobic glycolysis in a549 human lung epithelial cells
Viruses, 2020Co-Authors: Martin A. Prusinkiewicz, Peter Pelka, Gregory J Fonseca, Mackenzie J Dodge, Katelyn M Macneil, Sandi Radkojuettner, Joe S. MymrykAbstract:Viruses alter a multitude of host-cell processes to create a more optimal environment for viral replication. This includes altering metabolism to provide adequate substrates and energy required for replication. Typically, viral infections induce a metabolic phenotype resembling the Warburg effect, with an upregulation of glycolysis and a concurrent decrease in cellular respiration. Human adenovirus (HAdV) has been observed to induce the Warburg effect, which can be partially attributed to the adenovirus Protein early region 4, open reading frame 1 (E4orf1). E4orf1 regulates a multitude of host-cell processes to benefit viral replication and can influence cellular metabolism through the transcription factor avian myelocytomatosis viral oncogene homolog (MYC). However, E4orf1 does not explain the full extent of Warburg-like HAdV metabolic reprogramming, especially the accompanying decrease in cellular respiration. The HAdV Protein early region 1A (E1A) also modulates the function of the infected cell to promote viral replication. E1A can interact with a wide variety of host-cell Proteins, some of which have been shown to interact with metabolic enzymes independently of an interaction with E1A. To determine if the HAdV E1A Proteins are responsible for reprogramming cell metabolism, we measured the extracellular acidification rate and oxygen consumption rate of A549 human lung epithelial cells with constitutive endogenous expression of either of the two major E1A isoforms. This was followed by the characterization of transcript levels for genes involved in glycolysis and cellular respiration, and related metabolic pathways. Cells expressing the 13S encoded E1A isoform had drastically increased baseline glycolysis and lower maximal cellular respiration than cells expressing the 12S encoded E1A isoform. Cells expressing the 13S encoded E1A isoform exhibited upregulated expression of glycolysis genes and downregulated expression of cellular respiration genes. However, tricarboxylic acid cycle genes were upregulated, resembling anaplerotic metabolism employed by certain cancers. Upregulation of glycolysis and tricarboxylic acid cycle genes was also apparent in IMR-90 human primary lung fibroblast cells infected with a HAdV-5 mutant virus that expressed the 13S, but not the 12S encoded E1A isoform. In conclusion, it appears that the two major isoforms of E1A differentially influence cellular glycolysis and oxidative phosphorylation and this is at least partially due to the altered regulation of mRNA expression for the genes in these pathways.
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Metabolic Reprogramming of the Host Cell by Human Adenovirus Infection
MDPI AG, 2019Co-Authors: Martin A. Prusinkiewicz, Joe S. MymrykAbstract:Viruses are obligate intracellular parasites that alter many cellular processes to create an environment optimal for viral replication. Reprogramming of cellular metabolism is an important, yet underappreciated feature of many viral infections, as this ensures that the energy and substrates required for viral replication are available in abundance. Human adenovirus (HAdV), which is the focus of this review, is a small DNA tumor virus that reprograms cellular metabolism in a variety of ways. It is well known that HAdV infection increases glucose uptake and fermentation to lactate in a manner resembling the Warburg effect observed in many cancer cells. However, HAdV infection induces many other metabolic changes. In this review, we integrate the findings from a variety of proteomic and transcriptomic studies to understand the subtleties of metabolite and metabolic pathway control during HAdV infection. We review how the E4ORF1 Protein of HAdV enacts some of these changes and summarize evidence for reprogramming of cellular metabolism by the viral E1A Protein. Therapies targeting altered metabolism are emerging as cancer treatments, and similar targeting of aberrant components of virally reprogrammed metabolism could have clinical antiviral applications
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the adaptor Protein dcaf7 mediates the interaction of the adenovirus E1A oncoProtein with the Protein kinases dyrk1a and hipk2
Scientific Reports, 2016Co-Authors: Florian Glenewinkel, Joe S. Mymryk, Michael J Cohen, Cason R King, Sophie Kaspar, Simone Bamberglemper, Walter BeckerAbstract:DYRK1A is a constitutively active Protein kinase that has a critical role in growth and development which functions by regulating cell proliferation, differentiation and survival. DCAF7 (also termed WDR68 or HAN11) is a cellular binding partner of DYRK1A and also regulates signalling by the Protein kinase HIPK2. DCAF7 is an evolutionarily conserved Protein with a single WD40 repeat domain and has no catalytic activity. We have defined a DCAF7 binding motif of 12 amino acids in the N-terminal domain of class 1 DYRKs that is functionally conserved in DYRK1 orthologs from Xenopus, Danio rerio and the slime mold Dictyostelium discoideum. A similar sequence was essential for DCAF7 binding to HIPK2, whereas the closely related HIPK1 family member did not bind DCAF7. Immunoprecipitation and pulldown experiments identified DCAF7 as an adaptor for the association of the adenovirus E1A Protein with DYRK1A and HIPK2. Furthermore, DCAF7 was required for the hyperphosphorylation of E1A in DYRK1A or HIPK2 overexpressing cells. Our results characterize DCAF7 as a substrate recruiting subunit of DYRK1A and HIPK2 and suggest that it is required for the negative effect of DYRK1A on E1A-induced oncogenic transformation.
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the adenovirus 55 residue E1A Protein is a transcriptional activator and binds the unliganded thyroid hormone receptor
Journal of General Virology, 2014Co-Authors: Vishnuka D Arulsundaram, Paul G Walfish, Peter Pelka, Paul Webb, Ahmed F Yousef, Greg J Fonseca, John D Baxter, Joe S. MymrykAbstract:The early region 1A (E1A) of human adenovirus types 2 and 5 is differentially spliced to yield five distinct mRNAs that encode different Proteins. The smallest E1A RNA transcript encodes a 55 residue (55R) Protein that shares only 28 amino acid residues with the other E1A Proteins. Even though it is the most abundant E1A transcript at late times post-infection, little is known about the functions of this E1A isoform. In this study, we show that the E1A 55R Protein interacts with, and modulates the activity of the unliganded thyroid hormone receptor (TR). We demonstrate that E1A 55R contains a signature motif known as the CoRNR box that confers interaction with the unliganded TR; this motif was originally identified in cellular corepressors. Using a system reconstituted in the yeast Saccharomyces cerevisiae, which lack endogenous TR and TR coregulators, we show that E1A 55R nonetheless differs from cellular corepressors as it functions as a strong co-activator of TR-dependent transcription and that it possesses an intrinsic transcriptional activation domain. These data indicate that the E1A 55R Protein functions as a transcriptional regulator.
Thomas Shenk - One of the best experts on this subject based on the ideXlab platform.
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Adenovirus E1A Proteins interact with the cellular YY1 transcription factor.
Journal of virology, 1995Co-Authors: Brian A. Lewis, Edward Seto, Gregory E. Tullis, Nobuo Horikoshi, Roberto Weinmann, Thomas ShenkAbstract:The adenovirus 12S and 13S E1A Proteins have been shown to relieve repression mediated by the cellular transcription factor YY1. The 13S E1A Protein not only relieves repression but also activates transcription through YY1 binding sites. In this study, using a variety of in vivo and in vitro assays, we demonstrate that both E1A Proteins can bind to YY1, although the 13S E1A Protein binds more efficiently than the 12S E1A Protein. Two domains on the E1A Proteins interact with YY1: an amino-terminal sequence (residues 15 to 35) that is present in both E1A Proteins and a domain that includes at least a portion of conserved region 3 (residues 140 to 188) that is present in the 13S but not the 12S E1A Protein. Two domains on YY1 interact with E1A Proteins: one is contained within residues 54 to 260, and the other is contained within the carboxy-terminal domain of YY1 (residues 332 to 414). Cotransfection of a plasmid expressing carboxy-terminal amino acids 332 to 414 of YY1 fused to the GAL4 DNA-binding domain can inhibit expression from a reporter construct with GAL4 DNA binding sites in its promoter, and inclusion of a third plasmid expressing E1A Proteins can relieve the repression. Thus, we find a correlation between the ability of E1A to interact with the carboxy-terminal domain of YY1 and its ability to relieve repression caused by the carboxy-terminal domain of YY1. We propose that E1A Proteins normally relieve YY1-mediated transcriptional repression by binding directly to the cellular transcription factor.
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Two domains of p53 interact with the TATA-binding Protein, and the adenovirus 13S E1A Protein disrupts the association, relieving p53-mediated transcriptional repression.
Molecular and cellular biology, 1995Co-Authors: Nobuo Horikoshi, Anny Usheva, Roberto Weinmann, Jiandong Chen, Arnold J. Levine, Thomas ShenkAbstract:The tumor suppressor gene product p53 can activate and repress transcription. Both transcriptional activation and repression are thought to involve the direct interaction of p53 with the basal transcriptional machinery. Previous work has demonstrated an in vitro interaction between p53 and the TATA-binding Protein that requires amino acids 20 to 57 of p53 and amino acids 220 to 271 of the TATA-binding Protein. The present results show that a 75-amino-acid segment from the carboxy terminus of p53 also can bind to the TATA-binding Protein in vitro, and this interaction requires amino acids 217 to 268 of the TATA-binding Protein, essentially the same domain that is required for interaction with the amino-terminal domain of p53. A carboxy-terminal segment of p53 can mediate repression when bound to DNA as a GAL4-p53 fusion Protein. The amino- and carboxy-terminal p53 interactions occur within the domain on the TATA-binding Protein to which the adenovirus 13S E1A oncoProtein has previously been shown to bind. The 13S E1A oncoProtein can dissociate the complex formed between the carboxy-terminal domain of p53 and the TATA-binding Protein and relieve p53-mediated transcriptional repression. These results demonstrate that two independent domains of p53 can potentially interact with the TATA-binding Protein, and they define a mechanism--relief of repression--by which the 13S E1A oncoProtein can activate transcription through the TATA motif.
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adenovirus e4orf4 Protein binds to Protein phosphatase 2a and the complex down regulates E1A enhanced junb transcription
Journal of Virology, 1993Co-Authors: T Kleinberger, Thomas ShenkAbstract:Adenovirus E4orf4 Protein was previously shown to counteract transactivation of junB by cyclic AMP (cAMP) and E1A Protein. It was also shown to cause hypophosphorylation of E1A and c-Fos Proteins. Here we show that the E4orf4 Protein associates with Protein phosphatase 2A. All three subunits of the phosphatase are present in the complex, and the B subunit interacts directly with the viral Protein. The complex possesses a phosphatase activity typical of Protein phosphatase 2A, and the phosphatase mediates the E4orf4-induced down regulation of junB transcription. Thus, adenovirus E4orf4 Protein recruits Protein phosphatase 2A into a signal transduction pathway initiated by cAMP and E1A Protein.
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adenovirus e4orf4 Protein reduces phosphorylation of c fos and E1A Proteins while simultaneously reducing the level of ap 1
Journal of Virology, 1992Co-Authors: Ulrich Muller, T Kleinberger, Thomas ShenkAbstract:Abstract Adenovirus E1A Protein and cyclic AMP cooperate to induce transcription factor AP-1 and viral gene expression in mouse S49 cells. We report that a Protein encoded within the viral E4 gene region acts to counterbalance the induction of AP-1 DNA-binding activity by E1A and cyclic AMP. Studies with mutant adenoviruses demonstrated that in the absence of E4orf4 Protein, AP-1 DNA-binding activity is induced to substantially higher levels than in wild-type virus-infected cells. The induction is the result of increased production of JunB and c-Fos Proteins. Hyperphosphorylated forms of c-Fos and E1A Proteins accumulate in the absence of functional E4orf4 Protein. We propose that the E4orf4 Protein acts to inhibit the activity of a cellular kinase that phosphorylates both the E1A and c-Fos Proteins. Phosphorylation-dependent alterations in the activity of c-Fos, E1A, or some unidentified Protein might, then, lead to decreased synthesis of AP-1 components. This E4 function likely plays an important role in natural infections, since a mutant virus unable to express the E4orf4 Protein is considerably more cytotoxic than the wild-type virus.
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transcriptional repression by yy1 a human gli kruppel related Protein and relief of repression by adenovirus E1A Protein
Cell, 1991Co-Authors: Yang Shi, Edward Seto, Longsheng Chang, Thomas ShenkAbstract:Summary A sequence within the transcription control region of the adeno-associated virus P5 promoter has been shown to mediate transcriptional activation by the adenovirus E1A Protein. We report here that this same element mediates transcriptional repression in the abaence of E1A. Two cellular Proteins have been found to bind to overlapping regions within this sequence element. One of these Proteins, YY1, is responsible for the repression. E1A relieves repression exerted by YY1 and further activates transcription through its binding site. A YYl-specific cDNA has been isolated. Its sequence reveals YY1 to be a zinc finger Protein that belongs to the GLI-Kruppel gene family. The product of the cDNA binds to YY1 sites. When fused to the GAL4 DNA-binding domain, it is capable of repressing transcription directed by a promoter that contains GAL4- binding sites, and E1A Proteins can relieve the repression and activate transcription through the fusion Protein.
Arnold J Berk - One of the best experts on this subject based on the ideXlab platform.
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adenovirus E1A activation domain regulates h3 acetylation affecting varied steps in transcription at different viral promoters
Journal of Virology, 2018Co-Authors: Mario A Pennella, Nathan R Zemke, Arnold J BerkAbstract:Author(s): Hsu, Emily; Pennella, Mario A; Zemke, Nathan R; Eng, Carol; Berk, Arnold J | Abstract: How histone acetylation promotes transcription is not clearly understood. Here, we confirm an interaction between p300 and the adenovirus 2 large E1A activation domain (AD) and map the interacting regions in E1A by observing colocalization at an integrated lacO array of fusions of LacI-mCherry to E1A fragments with YFP-p300. Viruses with mutations in E1A subdomains were constructed and analyzed for kinetics of early viral RNA expression and association of acetylated H3K9, K18, K27, TBP, and RNA polymerase II (Pol II) across the viral genome. The results indicate that this E1A interaction with p300 is required for H3K18 and H3K27 acetylation at the E2early, E3, and E4 promoters and is required for TBP and Pol II association with the E2early promoter. In contrast, H3K18/27 acetylation was not required for TBP and Pol II association with the E3 and E4 promoters but was required for E4 transcription at a step subsequent to Pol II preinitiation complex assembly.IMPORTANCE Despite a wealth of data associating promoter and enhancer region histone N-terminal tail lysine acetylation with transcriptional activity, there are relatively few examples of studies that establish causation between these histone posttranslational modifications and transcription. While hypoacetylation of histone H3 lysines 18 and 27 is associated with repression, the step(s) in the overall process of transcription that is blocked at a hypoacetylated promoter is not clearly established in most instances. Studies presented here confirm that the adenovirus 2 large E1A Protein activation domain interacts with p300, as reported previously (P. Pelka, J. N. G. Ablack, J. Torchia, A. S. Turnell, R. J. A. Grand, J. S. Mymryk, Nucleic Acids Res 37:1095-1106, 2009, https://doi.org/10.1093/nar/gkn1057), and that the resulting acetylation of H3K18/27 affects varied steps in transcription at different viral promoters.
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adenovirus small E1A alters global patterns of histone modification
Science, 2008Co-Authors: Gregory A Horwitz, Kangling Zhang, Matthew A Mcbrian, Michael Grunstein, Siavash K Kurdistani, Arnold J BerkAbstract:Adenovirus small early region 1a (E1A) Protein drives cells into S phase by binding RB family Proteins and the closely related histone acetyl transferases p300 and CBP. The interaction with RB Proteins displaces them from DNA-bound E2F transcription factors, reversing their repression of cell cycle genes. However, it has been unclear how the E1A interaction with p300 and CBP promotes passage through the cell cycle. We show that this interaction causes a threefold reduction in total cellular histone H3 lysine 18 acetylation (H3K18ac). CBP and p300 are required for acetylation at this site because their knockdown causes specific hypoacetylation at H3K18. SV40 T antigen also induces H3K18 hypoacetylation. Because global hypoacetylation at this site is observed in prostate carcinomas with poor prognosis, this suggests that processes resulting in global H3K18 hypoacetylation may be linked to oncogenic transformation.
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in vivo association of adenovirus large E1A Protein with the human mediator complex in adenovirus infected and transformed cells
Journal of Virology, 2002Co-Authors: Gang Wang, Arnold J BerkAbstract:The adenovirus large E1A Protein activates transcription from early viral promoters by a mechanism that requires a forty amino acid zinc finger activation domain in E1A conserved region 3 (CR3). Recent results indicate that activation by a Gal4 DNA-binding domain-E1A-CR3 fusion requires an interaction between the E1A-CR3 zinc finger and the Sur2 subunit of the mammalian Mediator (of transcription) complex. Although several host Proteins have been shown to bind stably to E1A Proteins in adenovirus-infected and -transformed cells, an in vivo interaction with Mediator complex subunits has not been described previously. Using immunoprecipitation and gel filtration analyses of nuclear extracts prepared from HeLa cells infected with adenovirus 5 or mutants that express either large or small E1A specifically and from adenovirus 5-transformed cells, we report here that large E1A, but not small E1A, binds to Mediator complex in vivo. Only ∼1 to 10% of large E1A is bound to Mediator complex at 18 h postinfection and in transformed cells, probably explaining why Mediator complex subunits were not identified among cellular E1A-binding Proteins described earlier. Surprisingly, even though extracted Mediator can quantitatively bind to an E1A-CR3 affinity column, only on the order of 1% of cellular Mediator complex is bound by E1A in vivo. Much of the large E1A bound to Mediator in 293 cells is in a stable complex that includes RNA polymerase II, leading us to suggest that the interaction of E1A-CR3 with Mediator stabilizes the interaction of Mediator with the polymerase. This stabilization of the interaction between Mediator and RNA polymerase II may contribute to the mechanism of activation by E1A-CR3.
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mammalian srb mediator complex is targeted by adenovirus E1A Protein
Nature, 1999Co-Authors: Thomas G Boyer, Robert P Ricciardi, Michelle E D Martin, Emma Lees, Arnold J BerkAbstract:Adenovirus E1A Proteins prepare the host cell for viral replication, stimulating cell cycling and viral transcription through interactions with critical cellular regulatory Proteins such as RB and CBP. Here we show that the E1A zinc-finger domain that is required to activate transcription of viral early genes binds to a host-cell multiProtein complex containing homologues of yeast Srb/Mediator Proteins. This occurs through a stable interaction with the human homologue of Caenorhabditis elegans SUR-2, a Protein required for many developmental processes in the nematode. This human Srb/Mediator complex stimulates transcription in vitro in response to both the E1A zinc-finger and the herpes simplex virus VP16 activation domains. Interaction with human Sur-2 is also required for transcription to be activated by the activation domain of a transcription factor of the ETS-family in response to activated mitogen-activated Protein (MAP) kinase.
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the zinc finger region of the adenovirus E1A transactivating domain complexes with the tata box binding Protein
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: Jospeph V Geisberg, Arnold J Berk, Wes S Lee, Robert P RicciardiAbstract:Abstract The 289R E1A Protein of adenovirus transactivates a variety of viral and cellular promoters through Protein-Protein interactions. In earlier studies, mutational analyses of the E1A transactivating domain identified residues that are critical for transactivation and implied that the zinc finger region of the transactivating domain binds a transcription factor. Also, the E1A activation domain was found to bind to the TATA box binding Protein (TBP) in vitro. Here, we tested the significance of the E1A-TBP interaction for E1A transactivation by analyzing the effects of conservative substitutions at each of the 49 residues of the E1A activation domain. Seven of the substitutions significantly diminished TBP binding in vitro. All of these were in the zinc finger region and were defective for transactivation in vivo. The perfect correlation between reduced TBP binding and transactivation argues strongly that a direct interaction between the E1A activation domain and TBP is critical to the mechanism of E1A activation. This genetic analysis leads us to further suggest that another factor, which is limiting, is also necessary for E1A-mediated transactivation.
Roberto Weinmann - One of the best experts on this subject based on the ideXlab platform.
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Adenovirus E1A Proteins interact with the cellular YY1 transcription factor.
Journal of virology, 1995Co-Authors: Brian A. Lewis, Edward Seto, Gregory E. Tullis, Nobuo Horikoshi, Roberto Weinmann, Thomas ShenkAbstract:The adenovirus 12S and 13S E1A Proteins have been shown to relieve repression mediated by the cellular transcription factor YY1. The 13S E1A Protein not only relieves repression but also activates transcription through YY1 binding sites. In this study, using a variety of in vivo and in vitro assays, we demonstrate that both E1A Proteins can bind to YY1, although the 13S E1A Protein binds more efficiently than the 12S E1A Protein. Two domains on the E1A Proteins interact with YY1: an amino-terminal sequence (residues 15 to 35) that is present in both E1A Proteins and a domain that includes at least a portion of conserved region 3 (residues 140 to 188) that is present in the 13S but not the 12S E1A Protein. Two domains on YY1 interact with E1A Proteins: one is contained within residues 54 to 260, and the other is contained within the carboxy-terminal domain of YY1 (residues 332 to 414). Cotransfection of a plasmid expressing carboxy-terminal amino acids 332 to 414 of YY1 fused to the GAL4 DNA-binding domain can inhibit expression from a reporter construct with GAL4 DNA binding sites in its promoter, and inclusion of a third plasmid expressing E1A Proteins can relieve the repression. Thus, we find a correlation between the ability of E1A to interact with the carboxy-terminal domain of YY1 and its ability to relieve repression caused by the carboxy-terminal domain of YY1. We propose that E1A Proteins normally relieve YY1-mediated transcriptional repression by binding directly to the cellular transcription factor.
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Two domains of p53 interact with the TATA-binding Protein, and the adenovirus 13S E1A Protein disrupts the association, relieving p53-mediated transcriptional repression.
Molecular and cellular biology, 1995Co-Authors: Nobuo Horikoshi, Anny Usheva, Roberto Weinmann, Jiandong Chen, Arnold J. Levine, Thomas ShenkAbstract:The tumor suppressor gene product p53 can activate and repress transcription. Both transcriptional activation and repression are thought to involve the direct interaction of p53 with the basal transcriptional machinery. Previous work has demonstrated an in vitro interaction between p53 and the TATA-binding Protein that requires amino acids 20 to 57 of p53 and amino acids 220 to 271 of the TATA-binding Protein. The present results show that a 75-amino-acid segment from the carboxy terminus of p53 also can bind to the TATA-binding Protein in vitro, and this interaction requires amino acids 217 to 268 of the TATA-binding Protein, essentially the same domain that is required for interaction with the amino-terminal domain of p53. A carboxy-terminal segment of p53 can mediate repression when bound to DNA as a GAL4-p53 fusion Protein. The amino- and carboxy-terminal p53 interactions occur within the domain on the TATA-binding Protein to which the adenovirus 13S E1A oncoProtein has previously been shown to bind. The 13S E1A oncoProtein can dissociate the complex formed between the carboxy-terminal domain of p53 and the TATA-binding Protein and relieve p53-mediated transcriptional repression. These results demonstrate that two independent domains of p53 can potentially interact with the TATA-binding Protein, and they define a mechanism--relief of repression--by which the 13S E1A oncoProtein can activate transcription through the TATA motif.
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Direct interaction between adenovirus E1A Protein and the TATA box binding transcription factor IID.
Proceedings of the National Academy of Sciences of the United States of America, 1991Co-Authors: Nobuo Horikoshi, Danny Reinberg, Kathleen Maguire, Anastasia Kralli, Edio Maldonado, Roberto WeinmannAbstract:Adenovirus E1A has long been known to activate/repress cellular and viral transcription. The transcriptional activity of nuclear extracts was depleted after chromatography on immobilized E1A Protein columns that specifically retained the transcription factor (TF) IID. Stronger direct interactions between E1A and human TFIID than between E1A and yeast TFIID suggest that the unique sequences of the human Protein may be involved. We have demonstrated that this interaction occurs directly between bacterially produced E1A and bacterially produced human TFIID in a Protein blot assay. We propose that E1A Protein may transduce regulatory signals from upstream activators to basal elements of the transcriptional machinery by contacting TFIID.
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the retinoblastoma Protein copurifies with e2f i an E1A regulated inhibitor of the transcription factor e2f
Cell, 1991Co-Authors: Srilata Bagchi, Roberto Weinmann, Pradip RaychaudhuriAbstract:Abstract Recently, we identified an inhibitory Protein, E2F-I, that blocks the DNA-binding activity of the transcription factor E2F. We also showed that the adenovirus E1A Protein reverses this inhibitory activity of E2F-I, thereby restoring the DNA-binding activity of E2F. We have now further purified this inhibitory activity and show that the most purified preparation of E2F-I contains a 105 kd E1A-binding Protein. This 105 kd E1A-binding Protein cross-reacts with two different antibodies against the retinoblastoma (RB) gene product. Moreover, the RB gene product copurifies with E2F-I activity. Taken together, we conclude that the product of the RB gene is a part of E2F-I and is involved in the regulation of E2F activity.
Paul G Walfish - One of the best experts on this subject based on the ideXlab platform.
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the adenovirus 55 residue E1A Protein is a transcriptional activator and binds the unliganded thyroid hormone receptor
Journal of General Virology, 2014Co-Authors: Vishnuka D Arulsundaram, Paul G Walfish, Peter Pelka, Paul Webb, Ahmed F Yousef, Greg J Fonseca, John D Baxter, Joe S. MymrykAbstract:The early region 1A (E1A) of human adenovirus types 2 and 5 is differentially spliced to yield five distinct mRNAs that encode different Proteins. The smallest E1A RNA transcript encodes a 55 residue (55R) Protein that shares only 28 amino acid residues with the other E1A Proteins. Even though it is the most abundant E1A transcript at late times post-infection, little is known about the functions of this E1A isoform. In this study, we show that the E1A 55R Protein interacts with, and modulates the activity of the unliganded thyroid hormone receptor (TR). We demonstrate that E1A 55R contains a signature motif known as the CoRNR box that confers interaction with the unliganded TR; this motif was originally identified in cellular corepressors. Using a system reconstituted in the yeast Saccharomyces cerevisiae, which lack endogenous TR and TR coregulators, we show that E1A 55R nonetheless differs from cellular corepressors as it functions as a strong co-activator of TR-dependent transcription and that it possesses an intrinsic transcriptional activation domain. These data indicate that the E1A 55R Protein functions as a transcriptional regulator.
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the adenoviral E1A Protein displaces corepressors and relieves gene repression by unliganded thyroid hormone receptors in vivo
Cell Research, 2009Co-Authors: Joe S. Mymryk, Paul G Walfish, Ahmed F Yousef, Yukiyasu Sato, Andrew Ding, Rachel A Heimeier, Yunbo ShiAbstract:The human adenovirus type 5 early region 1A (E1A) is one of two oncogenes present in the adenovirus genome and functions by interfering with the activities of cellular regulatory Proteins. The E1A gene is alternatively spliced to yield five products. Earlier studies have revealed that E1A can regulate the function of thyroid hormone (T3) receptors (TRs). However, analysis in yeast compared with transfection studies in mammalian cell cultures yields surprisingly different effects. Here, we have examined the effect of E1A on TR function by using the frog oocyte in vivo system, where the effects of E1A can be studied in the context of chromatin. We demonstrate that different isoforms of E1A have distinct effects on TR function. The two longest forms inhibit both the repression by unliganded TR and activation by T3-bound TR. We further show that E1A binds to unliganded TR to displace the endogenous corepressor nuclear receptor corepressor, thus relieving the repression by unliganded TR. On the other hand, in the presence of T3, E1A inhibits gene activation by T3-bound TR indirectly, through a mechanism that requires its binding domain for the general coactivator p300. Taken together, our results thus indicate that E1A affects TR function through distinct mechanisms that are dependent upon the presence or absence of T3.
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the adenovirus E1A Protein targets the saga but not the ada transcriptional regulatory complex through multiple independent domains
Journal of Biological Chemistry, 2002Co-Authors: Michael Shuen, Nikita Avvakumov, Paul G Walfish, Chris J Brandl, Joe S. MymrykAbstract:Expression of the adenovirus E1A Protein in the simple eukaryote Saccharomyces cerevisiaeinhibits growth. We tested four regions of E1A that alter growth and transcription in mammalian cells for their effects in yeast when expressed as fusions to the Gal4p DNA binding domain. Expression of the N-terminal/conserved region (CR) 1 or CR3, but not of the CR2 or the C-terminal portion of E1A, inhibited yeast growth. Growth inhibition was relieved by deletion of the genes encoding the yGcn5p, Ngg1p, or Spt7p components of the SAGA transcriptional regulatory complex, but not the Ahc1p component of the related ADA complex, indicating that the N-terminal/CR1 and CR3 regions of E1A target the SAGA complex independently. Expression of the pCAF acetyltransferase, a mammalian homologue of yGcn5p, also suppressed growth inhibition by either portion of E1A. Furthermore, the N-terminal 29 residues and the CR3 portion of E1A interacted independently with yGcn5p and pCAF in vitro. Thus, two separate regions of E1A target the yGcn5p component of the SAGA transcriptional activation complex. A subregion of the N-terminal/CR1 fragment spanning residues 30–69 within CR1 also inhibited yeast growth in a SAGA-dependent fashion. However, this region did not interact with yGcn5p or pCAF, suggesting that it makes a third contact with another SAGA component. Our results provide a new model system to elucidate mechanisms by which E1A and the SAGA complex regulate transcription and growth.
