scholarly journals Interaction of the Papillomavirus E8∧E2C Protein with the Cellular CHD6 Protein Contributes to Transcriptional Repression

2010 ◽  
Vol 84 (18) ◽  
pp. 9505-9515 ◽  
Author(s):  
Jasmin Fertey ◽  
Ingo Ammermann ◽  
Michael Winkler ◽  
Reinhard Stöger ◽  
Thomas Iftner ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Dna Binding ◽  
Transcriptional Repression ◽  
Human Papillomaviruses ◽  
Hpv E6 ◽  
Host Cell Proteins ◽  
E6 And E7 ◽  
Site Competition ◽  
Rna Knockdown ◽  
Cellular Transcription

ABSTRACT Expression of the E6 and E7 oncogenes of high-risk human papillomaviruses (HPV) is controlled by cellular transcription factors and by viral E2 and E8∧E2C proteins, which are both derived from the HPV E2 gene. Both proteins bind to and repress the HPV E6/E7 promoter. Promoter inhibition has been suggested to be due to binding site competition with cellular transcription factors and to interactions of different cellular transcription modulators with the different amino termini of E2 and E8∧E2C. We have now identified the cellular chromodomain helicase DNA binding domain 6 protein (CHD6) as a novel interactor with HPV31 E8∧E2C by using yeast two-hybrid screening. Pull-down and coimmunoprecipitation assays indicate that CHD6 interacts with the HPV31 E8∧E2C protein via the E2C domain. This interaction is conserved, as it occurs also with the E8∧E2C proteins expressed by HPV16 and -18 and with the HPV31 E2 protein. Both RNA knockdown experiments and mutational analyses of the E2C domain suggest that binding of CHD6 to E8∧E2C contributes to the transcriptional repression of the HPV E6/E7 oncogene promoter. We provide evidence that CHD6 is also involved in transcriptional repression but not activation by E2. Taken together our results indicate that the E2C domain not only mediates specific DNA binding but also has an additional role in transcriptional repression by recruitment of the CHD6 protein. This suggests that repression of the E6/E7 promoter by E2 and E8∧E2C involves multiple interactions with host cell proteins through different protein domains.

scholarly journals Contribution of HDAC3 to transcriptional repression by the human papillomavirus 31 E8^E2 protein

2020 ◽  
Vol 101 (7) ◽  
pp. 751-759
Author(s):  
Marcel Dreer ◽  
Saskia Blondzik ◽  
Elke Straub ◽  
Thomas Iftner ◽  
Frank Stubenrauch
Keyword(s):  
Transcription Factors ◽  
Human Papillomavirus ◽  
Histone Deacetylase ◽  
Transcriptional Repression ◽  
Human Papillomaviruses ◽  
Related Protein ◽  
E2 Protein ◽  
Histone Deacetylase 3 ◽  
Cellular Genes ◽  
Cellular Transcription

Human papillomaviruses (HPV) such as HPV16 and HPV31 encode an E8^E2 protein that acts as a repressor of viral replication and transcription. E8^E2′s repression activities are mediated via the interaction with host-cell NCoR (nuclear receptor corepressor)/SMRT (silencing mediator of retinoid and thyroid receptors) corepressor complexes, which consist of NCoR, its homologue SMRT, GPS2 (G-protein pathway suppressor 2), HDAC3 (histone deacetylase 3), TBL1 (transducin b-like protein 1) and its homologue TBLR1 (TBL1-related protein 1). We now provide evidence that transcriptional repression by HPV31 E8^E2 is NCoR/SMRT-dependent but surprisingly always HDAC3-independent when analysing different HPV promoters. This is in contrast to the majority of several cellular transcription factors using NCoR/SMRT complexes whose transcriptional repression activities are both NCoR/SMRT- and HDAC3-dependent. However, NCoR/SMRT-dependent but HDAC3-independent repression has been described for specific cellular genes, suggesting that this may not be specific for HPV promoters but could be a feature of a subset of NCoR/SMRT-HDAC3 regulated genes.

scholarly journals Suppression of MicroRNA 424 Levels by Human Papillomaviruses Is Necessary for Differentiation-Dependent Genome Amplification

2017 ◽  
Vol 91 (24) ◽  
Author(s):  
Shiyuan Hong ◽  
Shouqiang Cheng ◽  
William Songock ◽  
Jason Bodily ◽  
Laimonis A. Laimins
Keyword(s):  
Dna Damage ◽  
Critical Role ◽  
Human Papillomaviruses ◽  
Expression Vectors ◽  
Hpv E6 ◽  
Damage Repair ◽  
Undifferentiated Cells ◽  
Efficient Replication ◽  
E6 And E7 ◽  
E7 Proteins

ABSTRACT High-risk human papillomaviruses (HPVs) link their life cycle to epithelial differentiation and require activation of DNA damage pathways for efficient replication. HPVs modulate the expression of cellular transcription factors, as well as cellular microRNAs (miRNAs) to control these activities. One miRNA that has been reported to be repressed in HPV-positive cancers of the cervix and oropharynx is miR-424. Our studies show that miR-424 levels are suppressed in cell lines that stably maintain HPV 31 or 16 episomes, as well as cervical cancer lines that contain integrated genomes such as SiHa. Introduction of expression vectors for miR-424 reduced both the levels of HPV genomes in undifferentiated cells and amplification upon differentiation. Our studies show that the levels of two putative targets of miR-424 that function in DNA damage repair, CHK1 and Wee1, are suppressed in HPV-positive cells, providing an explanation for why this microRNA is targeted in HPV-positive cells. IMPORTANCE We describe here for the first time a critical role for miR-424 in the regulation of HPV replication. HPV E6 and E7 proteins suppress the levels of miR-424, and this is important for controlling the levels of CHK1, which plays a central role in viral replication.

scholarly journals Role of the C-Terminal Binding Protein PXDLS Motif Binding Cleft in Protein Interactions and Transcriptional Repression

2006 ◽  
Vol 26 (21) ◽  
pp. 8202-8213 ◽  
Author(s):  
Kate G. R. Quinlan ◽  
Alexis Verger ◽  
Alister Kwok ◽  
Stella H. Y. Lee ◽  
José Perdomo ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Dna Binding ◽  
Protein Interactions ◽  
Transcriptional Repression ◽  
Histone Deacetylases ◽  
Gene Repression ◽  
Dna Binding Domains ◽  
Binding Domains ◽  
Binding Cleft ◽  
Partner Proteins

ABSTRACT C-terminal binding proteins (CtBPs) are multifunctional proteins that can mediate gene repression. CtBPs contain a cleft that binds Pro-X-Asp-Leu-Ser (PXDLS) motifs. PXDLS motifs occur in numerous transcription factors and in effectors of gene repression, such as certain histone deacetylases. CtBPs have been depicted as bridging proteins that self-associate and link PXDLS-containing transcription factors to PXDLS-containing chromatin-modifying enzymes. CtBPs also recruit effectors that do not contain recognizable PXDLS motifs. We have investigated the importance of the PXDLS binding cleft to CtBP's interactions with various partner proteins and to its ability to repress transcription. We used CtBP cleft mutant and cleft-filled fusion derivatives to distinguish between partner proteins that bind in the cleft and elsewhere on the CtBP surface. Functional assays demonstrate that CtBP mutants that carry defective clefts retain repression activity when fused to heterologous DNA-binding domains. This result suggests that the cleft is not essential for recruiting effectors. In contrast, when tested in the absence of a fused DNA-binding domain, disruption of the cleft abrogates repression activity. These results demonstrate that the PXDLS binding cleft is functionally important but suggest that it is primarily required for localization of the CtBP complex to promoter-bound transcription factors.

scholarly journals E6-mediated activation of JNK drives EGFR signalling to promote proliferation and viral oncoprotein expression in cervical cancer

2020 ◽  
Author(s):  
Ethan L. Morgan ◽  
James A. Scarth ◽  
Molly R. Patterson ◽  
Christopher W. Wasson ◽  
Georgia C. Hemingway ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Cell Proliferation ◽  
Cancer Cells ◽  
Human Papillomaviruses ◽  
Signalling Pathway ◽  
Viral Oncoprotein ◽  
Hpv E6 ◽  
Cervical Cancer Cells ◽  
E6 And E7 ◽  
Novel Therapeutic

AbstractHuman papillomaviruses (HPV) are a major cause of malignancy worldwide, contributing to ~5% of all human cancers including almost all cases of cervical cancer and a growing number of ano-genital and oral cancers. HPV-induced malignancy is primarily driven by the viral oncogenes, E6 and E7, which manipulate host cellular pathways to increase cell proliferation and enhance cell survival, ultimately predisposing infected cells to malignant transformation. Consequently, a more detailed understanding of viral-host interactions in HPV-associated disease offers the potential to identify novel therapeutic targets. Here, we identify that the c-Jun N-terminal kinase (JNK) signalling pathway is activated in cervical disease and in cervical cancer. The HPV E6 oncogene induces JNK1/2 phosphorylation in a manner that requires the E6 PDZ binding motif. We show that blockade of JNK1/2 signalling using small molecule inhibitors, or knockdown of the canonical JNK substrate c-Jun, reduces cell proliferation and induces apoptosis in cervical cancer cells. We further demonstrate that this phenotype is at least partially driven by JNK-dependent activation of EGFR signalling via increased expression of EGFR and the EGFR ligands EGF and HB-EGF. JNK/c-Jun signalling promoted the invasive potential of cervical cancer cells and was required for the expression of the epithelial to mesenchymal transition (EMT)-associated transcription factor Slug and the mesenchymal marker Vimentin. Furthermore, JNK/c-Jun signalling is required for the constitutive expression of HPV E6 and E7, which are essential for cervical cancer cell growth and survival. Together, these data demonstrate a positive feedback loop between the EGFR signalling pathway and HPV E6/E7 expression, identifying a regulatory mechanism in which HPV drives EGFR signalling to promote proliferation, survival and EMT. Thus, our study has identified a novel therapeutic target that may be beneficial for the treatment of cervical cancer.

scholarly journals Spindle assembly checkpoint signaling and sister chromatid cohesion are disrupted by HPV E6-mediated transformation

2017 ◽  
Vol 28 (15) ◽  
pp. 2035-2041 ◽  
Author(s):  
Hazheen K. Shirnekhi ◽  
Erin P. Kelley ◽  
Jennifer G. DeLuca ◽  
Jacob A. Herman
Keyword(s):  
Cancer Progression ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Mitotic Exit ◽  
Human Papillomaviruses ◽  
Checkpoint Signaling ◽  
Hpv E6 ◽  
Chromatid Cohesion ◽  
E6 And E7 ◽  
Transforming Proteins

Aneuploidy, a condition that results from unequal partitioning of chromosomes during mitosis, is a hallmark of many cancers, including those caused by human papillomaviruses (HPVs). E6 and E7 are the primary transforming proteins in HPV that drive tumor progression. In this study, we stably expressed E6 and E7 in noncancerous RPE1 cells and analyzed the specific mitotic defects that contribute to aneuploidy in each cell line. We find that E6 expression results in multiple chromosomes associated with one or both spindle poles, causing a significant mitotic delay. In most cells, the misaligned chromosomes eventually migrated to the spindle equator, leading to mitotic exit. In some cells, however, mitotic exit occurred in the presence of pole-associated chromosomes. We determined that this premature mitotic exit is due to defects in spindle assembly checkpoint (SAC) signaling, such that cells are unable to maintain a prolonged mitotic arrest in the presence of unaligned chromosomes. This SAC defect is caused in part by a loss of kinetochore-associated Mad2 in E6-expressing cells. Our results demonstrate that E6-expressing cells exhibit previously unappreciated mitotic defects that likely contribute to HPV-mediated cancer progression.

scholarly journals Human Papillomavirus Type 16 E6/E7 Upregulation of Nucleophosmin Is Important for Proliferation and Inhibition of Differentiation

2010 ◽  
Vol 84 (10) ◽  
pp. 5131-5139 ◽  
Author(s):  
Rachel McCloskey ◽  
Craig Menges ◽  
Alan Friedman ◽  
Daksha Patel ◽  
Dennis J. McCance
Keyword(s):  
Cellular Transformation ◽  
Human Papillomaviruses ◽  
Two Dimensional ◽  
Primary Cells ◽  
Human Papillomavirus Type 16 ◽  
Hpv E6 ◽  
Elevated Expression ◽  
E6 And E7 ◽  
First Time ◽  
Inhibition Of Differentiation

ABSTRACT The E6 and E7 oncoproteins of high-risk human papillomaviruses (HPVs) are together sufficient to cause cellular transformation. Nucleophosmin (NPM) was identified as a protein with increased levels in two-dimensional (2-D) gel analysis of human foreskin keratinocytes (HFKs) expressing E7 following methylcellulose-induced differentiation. Analysis of NPM expression in E7-expressing cells and E6- and E7-expressing cells in culture and in organotypic rafts confirmed the increased levels observed in 2-D gel analysis. The elevated expression of NPM was determined to be posttranscriptional and was attributed to increased v-akt murine thymoma viral oncogene (AKT) activity in the E6- and E7-expressing cells. Depletion of NPM caused a reduction in the replicative capacity of E7- and E6/E7-expressing HFKs and an increase in markers of differentiation. Also, the p53 and pRb tumor suppressor levels are increased with the knockdown of NPM in E6/E7-expressing cells, and, interestingly, p14ARF is relocalized from the nucleolus to the nucleoplasm and cytoplasm in these cells. The results show for the first time that NPM is required for the proliferation and inhibition of differentiation observed in HPV E6- and E7-expressing primary cells.

scholarly journals The Role of Long Noncoding RNAs in Human Papillomavirus-associated Pathogenesis

Pathogens ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 289 ◽  
Author(s):  
Surendra Sharma ◽  
Karl Munger
Keyword(s):  
Human Papillomavirus ◽  
Noncoding Rnas ◽  
Human Papillomaviruses ◽  
Long Noncoding Rnas ◽  
Protein Targets ◽  
Hpv E6 ◽  
Small Proteins ◽  
E6 And E7 ◽  
E7 Proteins

Infections with high-risk human papillomaviruses cause ~5% of all human cancers. E6 and E7 are the only viral genes that are consistently expressed in cancers, and they are necessary for tumor initiation, progression, and maintenance. E6 and E7 encode small proteins that lack intrinsic enzymatic activities and they function by binding to cellular regulatory molecules, thereby subverting normal cellular homeostasis. Much effort has focused on identifying protein targets of the E6 and E7 proteins, but it has been estimated that ~98% of the human transcriptome does not encode proteins. There is a growing interest in studying noncoding RNAs as biochemical targets and biological mediators of human papillomavirus (HPV) E6/E7 oncogenic activities. This review focuses on HPV E6/E7 targeting cellular long noncoding RNAs, a class of biologically versatile molecules that regulate almost every known biological process and how this may contribute to viral oncogenesis.

scholarly journals Transforming Properties of Beta-3 Human Papillomavirus E6 and E7 Proteins

mSphere ◽  
2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Lucia Minoni ◽  
Maria Carmen Romero-Medina ◽  
Assunta Venuti ◽  
Cécilia Sirand ◽  
Alexis Robitaille ◽  
...  
Keyword(s):  
High Risk ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Biological Properties ◽  
Human Papillomaviruses ◽  
Hpv E6 ◽  
Hpv Types ◽  
Beta 2 ◽  
E6 And E7

ABSTRACT The beta human papillomaviruses (HPVs) are subdivided into 5 species (beta-1 to beta-5), and they were first identified in the skin. However, the beta-3 species appears to be more highly represented in the mucosal epithelia than in the skin. Functional studies have also highlighted that beta-3 HPV49 shares some functional similarities with mucosal high-risk (HR) HPV16. Here, we describe the characterization of the in vitro transforming properties of the entire beta-3 species, which includes three additional HPV types: HPV75, HPV76, and HPV115. HPV49, HPV75, and HPV76 E6 and E7 (E6/E7), but not HPV115 E6 and E7, efficiently inactivate the p53 and pRb pathways and immortalize or extend the life span of human foreskin keratinocytes (HFKs). As observed for HR HPV16, cell cycle deregulation mediated by beta-3 HPV E6/E7 expression leads to p16INK4a accumulation, whereas no p16INK4a was detected in beta-2 HPV38 E6/E7 HFKs. As shown for HPV49 E6, HPV75 and HPV76 E6s degrade p53 by an E6AP/proteasome-mediated mechanism. Comparative analysis of cellular gene expression patterns of HFKs containing E6 and E7 from HR HPV16, beta-3 HPV types, and beta-2 HPV38 further highlights the functional similarities of HR HPV16 and beta-3 HPV49, HPV75, and HPV76. The expression profiles of these four HPV HFKs show some similarities and diverge substantially from those of beta-3 HPV115 E6/E7 and beta-2 HPV38 E6/E7 HFKs. In summary, our data show that beta-3 HPV types share some mechanisms with HR HPV types and pave the way for additional studies aiming to evaluate their potential role in human pathologies. IMPORTANCE Human papillomaviruses are currently classified in different genera. Mucosal HPVs belonging to the alpha genus have been clearly associated with carcinogenesis of the mucosal epithelium at different sites. Beta HPV types have been classified as cutaneous. Although findings indicate that some beta HPVs from species 1 and 2 play a role, together with UV irradiation, in skin cancer, very little is known about the transforming properties of most of the beta HPVs. This report shows the transforming activity of E6 and E7 from beta-3 HPV types. Moreover, it highlights that beta-3 HPVs share some biological properties more extensively with mucosal high-risk HPV16 than with beta-2 HPV38. This report provides new paradigms for a better understanding of the biology of the different HPV types and their possible association with lesions at mucosal and/or cutaneous epithelia.

scholarly journals Cellular transcription factors regulate human papillomavirus type 16 gene expression by binding to a subset of the DNA sequences recognized by the viral E2 protein

1999 ◽  
Vol 80 (8) ◽  
pp. 2087-2096 ◽  
Author(s):  
Hannah Lewis ◽  
Kenneth Webster ◽  
Ana-Maria Sanchez-Perez ◽  
Kevin Gaston
Keyword(s):  
Transcription Factors ◽  
Human Papillomavirus ◽  
Dna Sequences ◽  
Hpv 16 ◽  
E2 Protein ◽  
Human Papillomavirus Type 16 ◽  
Binding Factor ◽  
E6 And E7 ◽  
Cellular Transcription ◽  
Site Binding

Human papillomavirus type 16 (HPV-16) is a DNA tumour virus that has been implicated in the development of cervical cancer. The HPV-16 E2 protein binds to four sites that are present upstream of the viral P97 promoter and regulates transcription of the E6 and E7 oncogenes. Here, it is shown that cellular transcription factors bind to two of these E2 sites. One cellular E2 site-binding factor, which is here named CEF-1, binds tightly to E2 site 1. CEF-2, an unrelated cellular E2 site-binding factor, binds tightly to E2 site 3. Transient transfection studies performed in the absence of the E2 protein showed that mutations that blocked the binding of CEF-1 to E2 site 1 or CEF-2 to E2 site 3 significantly reduced P97 promoter activity. Further characterization of CEF-1 indicated that this factor has not previously been identified and that CEF-1 and E2 competed for binding at E2 site 1.

scholarly journals Characterization of Transcription Factor Binding to Human Papillomavirus Type 16 DNA during Cellular Differentiation

2006 ◽  
Vol 80 (9) ◽  
pp. 4356-4362 ◽  
Author(s):  
Andrew Carson ◽  
Saleem A. Khan
Keyword(s):  
Transcription Factors ◽  
Host Cell ◽  
Human Papillomaviruses ◽  
Host Protein ◽  
Regulatory Sequences ◽  
Regulatory Regions ◽  
Hpv 16 ◽  
Viral Genes ◽  
Cellular Transcription

ABSTRACT Human papillomaviruses (HPVs) require terminal differentiation of the host cell to produce infectious virions. The process of viral maturation involves a variety of changes in the expression/activity of host proteins that lead to high-level replication of the viral genome and expression of the late viral genes. Although the late promoter regions of HPV type 16 (HPV-16) are still not fully characterized, differentiation-dependent regulation of viral genes is thought to involve changes in the binding of host cell transcription factors to the viral promoter and regulatory regions. Currently, very little is known about specific cellular transcription factors involved in this process. We used the Panomics TransSignal protein/DNA array to identify changes in the levels of cellular transcription factors during methylcellulose-induced differentiation of W12 (20863) cells containing HPV-16. We then identified the differentially expressed transcription factors that specifically bind to HPV-16 DNA, including the known promoter and regulatory regions. We have validated the results obtained from the Panomics array by Western blot analysis. Furthermore, by chromatin immunoprecipitation assays, we have shown that many of the transcription factors identified in the above screen bind to the HPV-16 promoter/regulatory sequences in vivo and that the level of this binding is increased during differentiation. This approach identified approximately 30 transcription factors that specifically bind to HPV-16 sequences and may be involved in regulating HPV-16 transcription during differentiation. Although some of these transcription factors have previously been suggested to be involved in HPV-16 transcription, a number of them represent novel viral DNA-host protein interactions.

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