scholarly journals Serine/arginine-rich protein 30c activates human papillomavirus type 16 L1 mRNA expression via a bimodal mechanism

2011 ◽  
Vol 92 (10) ◽  
pp. 2411-2421 ◽  
Author(s):  
Monika Somberg ◽  
Xiaoze Li ◽  
Cecilia Johansson ◽  
Beatrice Orru ◽  
Roger Chang ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Mrna Expression ◽  
Capsid Protein ◽  
Splice Site ◽  
Inhibitory Effect ◽  
Mrna Splicing ◽  
Splice Sites ◽  
Hpv 16 ◽  
Human Papillomavirus Type 16 ◽  
Mitotic Cells

Two splice sites on the human papillomavirus type 16 (HPV-16) genome are used exclusively by the late capsid protein L1 mRNAs: SD3632 and SA5639. These splice sites are suppressed in mitotic cells. This study showed that serine/arginine-rich protein 30c (SRp30c), also named SFRS9, activated both SD3632 and SA5639 and induced production of L1 mRNA. Activation of HPV-16 L1 mRNA splicing by SRp30c required an intact arginine/serine-repeat (RS) domain of SRp30c. In addition to this effect, SRp30c could enhance L1 mRNA production indirectly by inhibiting the early 3′-splice site SA3358, which competed with the late 3′-splice site SA5639. SRp30c bound directly to sequences downstream of SA3358, suggesting that SRp30c inhibited the enhancer at SA3358 and caused a redirection of splicing to the late 3′-splice site SA5639. This inhibitory effect of SRp30c was independent of its RS domain. These results suggest that SRp30c can activate HPV-16 L1 mRNA expression via a bimodal mechanism: directly by stimulating splicing to late splice sites and indirectly by inhibiting competing early splice sites.

scholarly journals Multiple ASF/SF2 Sites in the Human Papillomavirus Type 16 (HPV-16) E4-Coding Region Promote Splicing to the Most Commonly Used 3′-Splice Site on the HPV-16 Genome

2010 ◽  
Vol 84 (16) ◽  
pp. 8219-8230 ◽  
Author(s):  
Monika Somberg ◽  
Stefan Schwartz
Keyword(s):  
Cervical Cancer ◽  
Human Papillomavirus ◽  
Splice Site ◽  
Binding Sites ◽  
Mrna Levels ◽  
Coding Region ◽  
Cervical Lesions ◽  
Hpv 16 ◽  
Human Papillomavirus Type 16 ◽  
E6 And E7

ABSTRACT Our results presented here demonstrate that the most abundant human papillomavirus type 16 (HPV-16) mRNAs expressing the viral oncogenes E6 and E7 are regulated by cellular ASF/SF2, itself defined as a proto-oncogene and overexpressed in cervical cancer cells. We show that the most frequently used 3′-splice site on the HPV-16 genome, site SA3358, which is used to produce primarily E4, E6, and E7 mRNAs, is regulated by ASF/SF2. Splice site SA3358 is immediately followed by 15 potential binding sites for the splicing factor ASF/SF2. Recombinant ASF/SF2 binds to the cluster of ASF/SF2 sites. Mutational inactivation of all 15 sites abolished splicing to SA3358 and redirected splicing to the downstream-located, late 3′-splice site SA5639. Overexpression of a mutant ASF/SF2 protein that lacks the RS domain, also totally inhibited the usage of SA3358 and redirected splicing to the late 3′-splice site SA5639. The 15 ASF/SF2 binding sites could be replaced by an ASF/SF2-dependent, HIV-1-derived splicing enhancer named GAR. This enhancer was also inhibited by the mutant ASF/SF2 protein that lacks the RS domain. Finally, silencer RNA (siRNA)-mediated knockdown of ASF/SF2 caused a reduction in spliced HPV-16 mRNA levels. Taken together, our results demonstrate that the major HPV-16 3′-splice site SA3358 is dependent on ASF/SF2. SA3358 is used by the most abundantly expressed HPV-16 mRNAs, including those encoding E6 and E7. High levels of ASF/SF2 may therefore be a requirement for progression to cervical cancer. This is supported by our earlier findings that ASF/SF2 is overexpressed in high-grade cervical lesions and cervical cancer.

scholarly journals Polypyrimidine Tract Binding Protein Induces Human Papillomavirus Type 16 Late Gene Expression by Interfering with Splicing Inhibitory Elements at the Major Late 5′ Splice Site, SD3632

2008 ◽  
Vol 82 (7) ◽  
pp. 3665-3678 ◽  
Author(s):  
Monika Somberg ◽  
Xiaomin Zhao ◽  
Monika Fröhlich ◽  
Magnus Evander ◽  
Stefan Schwartz
Keyword(s):  
Gene Expression ◽  
Human Papillomavirus ◽  
Splice Site ◽  
Late Gene ◽  
Polypyrimidine Tract ◽  
Late Gene Expression ◽  
Hpv 16 ◽  
Human Papillomavirus Type 16 ◽  
Polypyrimidine Tract Binding Protein ◽  
Cellular Factors

ABSTRACT We have initiated a screen for cellular factors that can induce human papillomavirus type 16 (HPV-16) late gene expression in human cancer cells. We report that the overexpression of polypyrimidine tract binding protein (PTB), also known as heterologous nuclear ribonucleoprotein I (hnRNP I), induces HPV-16 late gene expression in cells transfected with subgenomic HPV-16 plasmids or with full-length HPV-16 genomes and in persistently HPV-16-infected cells. In contrast, other hnRNPs such as hnRNP B1/A2, hnRNP F, and hnRNP Q do not induce HPV-16 late gene expression. PTB activates SD3632, the only 5′ splice site on the HPV-16 genome that is used exclusively by late mRNAs. PTB interferes with splicing inhibitory sequences located immediately upstream and downstream of SD3632, thereby activating late gene expression. One AU-rich PTB-responsive element was mapped to a 198-nucleotide sequence located downstream of SD3632. The deletion of this element induced HPV-16 late gene expression in the absence of PTB. Our results suggest that the overexpression of PTB interferes with cellular factors that interact with the inhibitory sequences. One may speculate that an increase in PTB levels or a reduction in the concentration of a PTB antagonist is required for the activation of HPV-16 late gene expression during the viral life cycle.

scholarly journals SF2/ASF Binds the Human Papillomavirus Type 16 Late RNA Control Element and Is Regulated during Differentiation of Virus-Infected Epithelial Cells

2004 ◽  
Vol 78 (19) ◽  
pp. 10598-10605 ◽  
Author(s):  
Maria G. McPhillips ◽  
Thanaporn Veerapraditsin ◽  
Sarah A. Cumming ◽  
Dimitra Karali ◽  
Steven G. Milligan ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Epithelial Cells ◽  
Posttranscriptional Regulation ◽  
Regulatory Element ◽  
Sr Proteins ◽  
Control Element ◽  
Splice Sites ◽  
Late Gene Expression ◽  
Hpv 16 ◽  
Human Papillomavirus Type 16

ABSTRACT Pre-mRNA splicing occurs in the spliceosome, which is composed of small ribonucleoprotein particles (snRNPs) and many non-snRNP components. SR proteins, so called because of their C-terminal arginine- and serine-rich domains (RS domains), are essential members of this class. Recruitment of snRNPs to 5′ and 3′ splice sites is mediated and promoted by SR proteins. SR proteins also bridge splicing factors across exons to help to define these units and have a central role in alternative and enhancer-dependent splicing. Here, we show that the SR protein SF2/ASF is part of a complex that forms upon the 79-nucleotide negative regulatory element (NRE) that is thought to be pivotal in posttranscriptional regulation of late gene expression in human papillomavirus type 16 (HPV-16). However, the NRE does not contain any active splice sites, is located in the viral late 3′ untranslated region, and regulates RNA-processing events other than splicing. The level of expression and extent of phosphorylation of SF2/ASF are upregulated with epithelial differentiation, as is subcellular distribution, specifically in HPV-16-infected epithelial cells, and expression levels are controlled, at least in part, by the virus transcription regulator E2.

scholarly journals A Splicing Enhancer in the E4 Coding Region of Human Papillomavirus Type 16 Is Required for Early mRNA Splicing and Polyadenylation as Well as Inhibition of Premature Late Gene Expression

2005 ◽  
Vol 79 (18) ◽  
pp. 12002-12015 ◽  
Author(s):  
Margaret Rush ◽  
Xiaomin Zhao ◽  
Stefan Schwartz
Keyword(s):  
Gene Expression ◽  
Human Papillomavirus ◽  
Splice Site ◽  
Late Gene ◽  
Coding Region ◽  
Late Gene Expression ◽  
Hpv 16 ◽  
Human Papillomavirus Type 16 ◽  
Early Region ◽  
Splicing Enhancer

ABSTRACT Successful inhibition of human papillomavirus type 16 (HPV-16) late gene expression early in the life cycle is essential for persistence of infection, the highest risk factor for cervical cancer. Our study aimed to locate regulatory RNA elements in the early region of HPV-16 that influence late gene expression. For this purpose, subgenomic HPV-16 expression plasmids under control of the strong human cytomegalovirus immediate early promoter were used. An exonic splicing enhancer that firmly supported the use of the E4 3′ splice site at position 3358 in the early region of the HPV-16 genome was identified. The enhancer was mapped to a 65-nucleotide AC-rich sequence located approximately 100 nucleotides downstream of the position 3358 3′ splice site. Deletion of the enhancer caused loss of both splicing at the upstream position 3358 3′ splice site and polyadenylation at the early polyadenylation signal, pAE. Direct splicing occurred at the competing L1 3′ splice site at position 5639 in the late region. Optimization of the position 3358 3′ splice site restored splicing to that site and polyadenylation at pAE. Additionally, a sequence of 40 nucleotides with a negative effect on late mRNA production was located immediately downstream of the enhancer. As the E4 3′ splice site is employed by both early and late mRNAs, the enhancer constitutes a key regulator of temporal HPV-16 gene expression, which is required for early mRNA production as well as for the inhibition of premature late gene expression.

scholarly journals Sequences homologous to 5' splice sites are required for the inhibitory activity of papillomavirus late 3' untranslated regions

1994 ◽  
Vol 14 (8) ◽  
pp. 5278-5289 ◽  
Author(s):  
P A Furth ◽  
W T Choe ◽  
J H Rex ◽  
J C Byrne ◽  
C C Baker
Keyword(s):  
Human Papillomavirus ◽  
Splice Site ◽  
Inhibitory Activity ◽  
Site Directed Mutagenesis ◽  
Untranslated Regions ◽  
Sequence Motifs ◽  
Splice Sites ◽  
Late Gene Expression ◽  
Human Papillomavirus Type 16 ◽  
Cytoplasmic Rna

Expression of bovine papillomavirus type 1 (BPV-1) late genes is limited to terminally differentiated keratinocytes in an infected epithelium. We have previously shown that although the BPV-1 late polyadenylation site is functional in nonpermissive cells, a 53-nucleotide (nt) fragment of the late 3' untranslated region acts posttranscriptionally to reduce polyadenylated cytoplasmic RNA levels. This 53-nt fragment does not appear to function by destabilizing polyadenylated cytoplasmic RNA (P. A. Furth and C. C. Baker, J. Virol. 65:5806-5812, 1991). In this study, we used site-directed mutagenesis and deletion analysis to demonstrate that the sequence AAG/GUAAGU, which is identical to the consensus 5' splice site sequence, was both necessary and sufficient for the inhibitory activity of the 53-nt fragment. Furthermore, base pairing between the 5' end of the U1 small nuclear RNA and this 5' splice site-like sequence was shown to be required for the inhibitory activity in vivo. We have also further mapped the human papillomavirus type 16 late 3' inhibitory element (I. M. Kennedy, J. K. Haddow, and J. B. Clements, J. Virol. 65:2093-2097, 1991) to a 51-nt region containing four overlapping sequence motifs with partial homology to 5' splice sites. Mutation of each of these motifs demonstrated that only one of these motifs is required for the inhibitory activity. However, the presence of the other motifs may contribute to the full inhibitory activity of the element. No BPV-1 or human papillomavirus type 16 mRNAs which are spliced by using the potential 5' splice sites present in the viral late 3' untranslated regions have been identified. This suggests that the primary function of these 5' splice site-like sequences is the inhibition of late gene expression. The most likely mechanism of action of these elements is reduction of polyadenylation efficiency, perhaps through interference with 3'-terminal exon definition.

scholarly journals Identification of a Human Papillomavirus Type 16-Specific Epitope on the C-Terminal Arm of the Major Capsid Protein L1

2003 ◽  
Vol 77 (21) ◽  
pp. 11625-11632 ◽  
Author(s):  
Joseph J. Carter ◽  
Greg C. Wipf ◽  
Sarah F. Benki ◽  
Neil D. Christensen ◽  
Denise A. Galloway
Keyword(s):  
Amino Acids ◽  
Monoclonal Antibodies ◽  
Human Papillomavirus ◽  
Binding Site ◽  
Capsid Protein ◽  
Major Capsid Protein ◽  
Molecular Model ◽  
Hpv 16 ◽  
Human Papillomavirus Type 16 ◽  
Antibody Binding Site

ABSTRACT To characterize epitopes on human papillomavirus (HPV) virus-like particles (VLPs), a panel of mutated HPV-16 VLPs was created. Each mutated VLP had residues substituted from HPV-31 or HPV-52 L1 sequences to the HPV-16 L1 backbone. Mutations were created on the HPV-31 and −52 L1 proteins to determine if HPV-16 type-specific recognition could be transferred. Correct folding of the mutated proteins was verified by resistance to trypsin digestion and by binding to one or more conformation-dependent monoclonal antibodies. Several of the antibodies tested were found to bind to regions already identified as being important for HPV VLP recognition (loops DE, EF, FG, and HI). Sequences at both ends of the long FG loop (amino acids 260 to 290) were required for both H16.V5 and H16.E70 reactivity. A new antibody-binding site was discovered on the C-terminal arm of L1 between positions 427 and 445. Recognition of these residues by the H16.U4 antibody suggests that this region is surface exposed and supports a recently proposed molecular model of HPV VLPs.

scholarly journals Sequences homologous to 5' splice sites are required for the inhibitory activity of papillomavirus late 3' untranslated regions.

1994 ◽  
Vol 14 (8) ◽  
pp. 5278-5289 ◽  
Author(s):  
P A Furth ◽  
W T Choe ◽  
J H Rex ◽  
J C Byrne ◽  
C C Baker
Keyword(s):  
Human Papillomavirus ◽  
Splice Site ◽  
Inhibitory Activity ◽  
Site Directed Mutagenesis ◽  
Untranslated Regions ◽  
Sequence Motifs ◽  
Splice Sites ◽  
Late Gene Expression ◽  
Human Papillomavirus Type 16 ◽  
Cytoplasmic Rna

Expression of bovine papillomavirus type 1 (BPV-1) late genes is limited to terminally differentiated keratinocytes in an infected epithelium. We have previously shown that although the BPV-1 late polyadenylation site is functional in nonpermissive cells, a 53-nucleotide (nt) fragment of the late 3' untranslated region acts posttranscriptionally to reduce polyadenylated cytoplasmic RNA levels. This 53-nt fragment does not appear to function by destabilizing polyadenylated cytoplasmic RNA (P. A. Furth and C. C. Baker, J. Virol. 65:5806-5812, 1991). In this study, we used site-directed mutagenesis and deletion analysis to demonstrate that the sequence AAG/GUAAGU, which is identical to the consensus 5' splice site sequence, was both necessary and sufficient for the inhibitory activity of the 53-nt fragment. Furthermore, base pairing between the 5' end of the U1 small nuclear RNA and this 5' splice site-like sequence was shown to be required for the inhibitory activity in vivo. We have also further mapped the human papillomavirus type 16 late 3' inhibitory element (I. M. Kennedy, J. K. Haddow, and J. B. Clements, J. Virol. 65:2093-2097, 1991) to a 51-nt region containing four overlapping sequence motifs with partial homology to 5' splice sites. Mutation of each of these motifs demonstrated that only one of these motifs is required for the inhibitory activity. However, the presence of the other motifs may contribute to the full inhibitory activity of the element. No BPV-1 or human papillomavirus type 16 mRNAs which are spliced by using the potential 5' splice sites present in the viral late 3' untranslated regions have been identified. This suggests that the primary function of these 5' splice site-like sequences is the inhibition of late gene expression. The most likely mechanism of action of these elements is reduction of polyadenylation efficiency, perhaps through interference with 3'-terminal exon definition.

scholarly journals Identification of an hnRNP A1-Dependent Splicing Silencer in the Human Papillomavirus Type 16 L1 Coding Region That Prevents Premature Expression of the Late L1 Gene

2004 ◽  
Vol 78 (20) ◽  
pp. 10888-10905 ◽  
Author(s):  
Xiaomin Zhao ◽  
Margaret Rush ◽  
Stefan Schwartz
Keyword(s):  
Human Papillomavirus ◽  
Splice Site ◽  
Early Stage ◽  
Eukaryotic Expression ◽  
Hnrnp A1 ◽  
Coding Region ◽  
Late Gene Expression ◽  
Hpv 16 ◽  
Human Papillomavirus Type 16 ◽  
Splicing Silencer

ABSTRACT We have previously identified cis-acting RNA sequences in the human papillomavirus type 16 (HPV-16) L1 coding region which inhibit expression of L1 from eukaryotic expression plasmids. Here we have determined the function of one of these RNA elements, and we provide evidence that this RNA element is a splicing silencer which suppresses the use of the 3′ splice site located immediately upstream of the L1 AUG. We also show that this splice site is inefficiently utilized as a result of a suboptimal polypyrimidine tract. Introduction of point mutations in the L1 coding region that altered the RNA sequence without affecting the L1 protein sequence resulted in the inactivation of the splicing silencer and induced splicing to the L1 3′ splice site. These mutations also prevented the interaction of the RNA silencer with a 35-kDa cellular protein identified here as hnRNP A1. The splicing silencer in L1 inhibits splicing in vitro, and splicing can be restored by the addition of RNAs containing an hnRNP A1 binding site to the reaction, demonstrating that hnRNP A1 inhibits splicing of the late HPV-16 mRNAs through the splicing silencer sequence. While we show that one role of the splicing silencer is to determine the ratio between partially spliced L2/L1 mRNAs and spliced L1 mRNAs, we also demonstrate that it inhibits splicing from the major 5′ splice site in the early region to the L1 3′ splice site, thereby playing an essential role in preventing late gene expression at an early stage of the viral life cycle. We speculate that the activity of the splicing silencer and possibly the concentration of hnRNP A1 in the HPV-16-infected cell determines the ability of the virus to establish a persistent infection which remains undetected by the host immune surveillance.

scholarly journals U1 small nuclear RNAs with altered specificity can be stably expressed in mammalian cells and promote permanent changes in pre-mRNA splicing.

1993 ◽  
Vol 13 (5) ◽  
pp. 2666-2676 ◽  
Author(s):  
J B Cohen ◽  
S D Broz ◽  
A D Levinson
Keyword(s):  
Splice Site ◽  
Mammalian Cells ◽  
Mrna Processing ◽  
Mrna Splicing ◽  
Small Nuclear Rna ◽  
Splice Sites ◽  
Gene Complementation ◽  
Small Nuclear Rnas ◽  
Nuclear Rna ◽  
Mutant Genes

Pre-mRNA 5' splice site activity depends, at least in part, on base complementarity to U1 small nuclear RNA. In transient coexpression assays, defective 5' splice sites can regain activity in the presence of U1 carrying compensatory changes, but it is unclear whether such mutant U1 RNAs can be permanently expressed in mammalian cells. We have explored this issue to determine whether U1 small nuclear RNAs with altered specificity may be of value to rescue targeted mutant genes or alter pre-mRNA processing profiles. This effort was initiated following our observation that U1 with specificity for a splice site associated with an alternative H-ras exon substantially reduced the synthesis of the potentially oncogenic p21ras protein in transient assays. We describe the development of a mammalian complementation system that selects for removal of a splicing-defective intron placed within a drug resistance gene. Complementation was observed in proportion to the degree of complementarity between transfected mutant U1 genes and different defective splice sites, and all cells selected in this manner were found to express mutant U1 RNA. In addition, these cells showed specific activation of defective splice sites presented by an unlinked reporter gene. We discuss the prospects of this approach to permanently alter the expression of targeted genes in mammalian cells.

Detection of Class-Specific Antibodies to Baculovirus-Derived Human Papillomavirus Type 16 (HPV-16) Capsid Proteins

1994 ◽  
pp. 155-160 ◽  
Author(s):  
John Cason ◽  
Parminder K. Kambo ◽  
Bhavneet Shergill ◽  
John Bible ◽  
Barbara Kell ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Capsid Proteins ◽  
Hpv 16 ◽  
Specific Antibodies ◽  
Human Papillomavirus Type 16
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