scholarly journals Selection of the bovine papillomavirus type 1 nucleotide 3225 3' splice site is regulated through an exonic splicing enhancer and its juxtaposed exonic splicing suppressor.

1996 ◽  
Vol 70 (7) ◽  
pp. 4691-4699 ◽  
Author(s):  
Z M Zheng ◽  
P He ◽  
C C Baker
Keyword(s):  
Splice Site ◽  
Bovine Papillomavirus ◽  
Exonic Splicing Enhancer ◽  
Splicing Enhancer ◽  
Selection Of

scholarly journals Exonic Splicing Enhancer-Dependent Selection of the Bovine Papillomavirus Type 1 Nucleotide 3225 3′ Splice Site Can Be Rescued in a Cell Lacking Splicing Factor ASF/SF2 through Activation of the Phosphatidylinositol 3-Kinase/Akt Pathway

2003 ◽  
Vol 77 (3) ◽  
pp. 2105-2115 ◽  
Author(s):  
Xuefeng Liu ◽  
Akila Mayeda ◽  
Mingfang Tao ◽  
Zhi-Ming Zheng
Keyword(s):  
Splice Site ◽  
Rna Splicing ◽  
Viral Rna ◽  
Splicing Factor ◽  
Rna Expression ◽  
Bovine Papillomavirus ◽  
Phosphatidylinositol 3 Kinase ◽  
Selection Of ◽  
Phosphatidylinositol 3

ABSTRACT Bovine papillomavirus type 1 (BPV-1) late pre-mRNAs are spliced in keratinocytes in a differentiation-specific manner: the late leader 5′ splice site alternatively splices to a proximal 3′ splice site (at nucleotide 3225) to express L2 or to a distal 3′ splice site (at nucleotide 3605) to express L1. Two exonic splicing enhancers, each containing two ASF/SF2 (alternative splicing factor/splicing factor 2) binding sites, are located between the two 3′ splice sites and have been identified as regulating alternative 3′ splice site usage. The present report demonstrates for the first time that ASF/SF2 is required under physiological conditions for the expression of BPV-1 late RNAs and for selection of the proximal 3′ splice site for BPV-1 RNA splicing in DT40-ASF cells, a genetically engineered chicken B-cell line that expresses only human ASF/SF2 controlled by a tetracycline-repressible promoter. Depletion of ASF/SF2 from the cells by tetracycline greatly decreased viral RNA expression and RNA splicing at the proximal 3′ splice site while increasing use of the distal 3′ splice site in the remaining viral RNAs. Activation of cells lacking ASF/SF2 through anti-immunoglobulin M-B-cell receptor cross-linking rescued viral RNA expression and splicing at the proximal 3′ splice site and enhanced Akt phosphorylation and expression of the phosphorylated serine/arginine-rich (SR) proteins SRp30s (especially SC35) and SRp40. Treatment with wortmannin, a specific phosphatidylinositol 3-kinase/Akt kinase inhibitor, completely blocked the activation-induced activities. ASF/SF2 thus plays an important role in viral RNA expression and splicing at the proximal 3′ splice site, but activation-rescued viral RNA expression and splicing in ASF/SF2-depleted cells is mediated through the phosphatidylinositol 3-kinase/Akt pathway and is associated with the enhanced expression of other SR proteins.

scholarly journals Regulation of vif mRNA Splicing by Human Immunodeficiency Virus Type 1 Requires 5′ Splice Site D2 and an Exonic Splicing Enhancer To Counteract Cellular Restriction Factor APOBEC3G

2009 ◽  
Vol 83 (12) ◽  
pp. 6067-6078 ◽  
Author(s):  
Dibyakanti Mandal ◽  
Colin M. Exline ◽  
Zehua Feng ◽  
C. Martin Stoltzfus
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Splice Site ◽  
Wild Type ◽  
Exonic Splicing Enhancer ◽  
Immunodeficiency Virus ◽  
Splicing Enhancer ◽  
Hiv 1

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) accessory protein Vif is encoded by an incompletely spliced mRNA resulting from splicing of the major splice donor in the HIV-1 genome, 5′ splice site (5′ss) D1, to the first splice acceptor, 3′ss A1. We have shown previously that splicing of HIV-1 vif mRNA is tightly regulated by suboptimal 5′ss D2, which is 50 nucleotides downstream of 3′ss A1; a GGGG silencer motif proximal to 5′ss D2; and an SRp75-dependent exonic splicing enhancer (ESEVif). In agreement with the exon definition hypothesis, mutations within 5′ss D2 that are predicted to increase or decrease U1 snRNP binding affinity increase or decrease the usage of 3′ss A1 (D2-up and D2-down mutants, respectively). In this report, the importance of 5′ss D2 and ESEVif for avoiding restriction of HIV-1 by APOBEC3G (A3G) was determined by testing the infectivities of a panel of mutant viruses expressing different levels of Vif. The replication of D2-down and ESEVif mutants in permissive CEM-SS cells was not significantly different from that of wild-type HIV-1. Mutants that expressed Vif in 293T cells at levels greater than 10% of that of the wild type replicated similarly to the wild type in H9 cells, and Vif levels as low as 4% were affected only modestly in H9 cells. This is in contrast to Vif-deleted HIV-1, whose replication in H9 cells was completely inhibited. To test whether elevated levels of A3G inhibit replication of D2-down and ESEVif mutants relative to wild-type virus replication, a Tet-off Jurkat T-cell line that expressed approximately 15-fold-higher levels of A3G than control Tet-off cells was generated. Under these conditions, the fitness of all D2-down mutant viruses was reduced relative to that of wild-type HIV-1, and the extent of inhibition was correlated with the level of Vif expression. The replication of an ESEVif mutant was also inhibited only at higher levels of A3G. Thus, wild-type 5′ss D2 and ESEVif are required for production of sufficient Vif to allow efficient HIV-1 replication in cells expressing relatively high levels of A3G.

scholarly journals An Exonic Splicing Enhancer Offsets the Atypical GU-rich 3′ Splice Site of Human Apolipoprotein A-II Exon 3

2004 ◽  
Vol 279 (38) ◽  
pp. 39331-39339 ◽  
Author(s):  
Pablo Arrisi-Mercado ◽  
Maurizio Romano ◽  
Andres F. Muro ◽  
Francisco E. Baralle
Keyword(s):  
Splice Site ◽  
Exonic Splicing Enhancer ◽  
Human Apolipoprotein ◽  
Apolipoprotein A ◽  
Splicing Enhancer

scholarly journals A Korean case of neurofibromatosis type 1 with an exonic splicing enhancer site mutation

2014 ◽  
Vol 11 (1) ◽  
pp. 40-42 ◽  
Author(s):  
Sangwook Park ◽  
Young Bae Sohn ◽  
In-Soon Chung ◽  
Ji-Hee Hong ◽  
Eun-Jung Jung ◽  
...  
Keyword(s):  
Neurofibromatosis Type 1 ◽  
Neurofibromatosis Type ◽  
Site Mutation ◽  
Exonic Splicing Enhancer ◽  
Splicing Enhancer

scholarly journals Control of the Papillomavirus Early-to-Late Switch by Differentially Expressed SRp20

2008 ◽  
Vol 83 (1) ◽  
pp. 167-180 ◽  
Author(s):  
Rong Jia ◽  
Xuefeng Liu ◽  
Mingfang Tao ◽  
Michael Kruhlak ◽  
Ming Guo ◽  
...  
Keyword(s):  
Keratinocyte Differentiation ◽  
Bovine Papillomavirus ◽  
Cellular Transcription Factor ◽  
Monolayer Cultures ◽  
Papillomavirus Infection ◽  
Alternative Mrna Splicing ◽  
E6 And E7 ◽  
Cellular Transcription ◽  
Selection Of

ABSTRACT The viral early-to-late switch of papillomavirus infection is tightly linked to keratinocyte differentiation and is mediated in part by alternative mRNA splicing. Here, we report that SRp20, a cellular splicing factor, controls the early-to-late switch via interactions with A/C-rich RNA elements. An A/C-rich SE4 element regulates the selection of a bovine papillomavirus type 1 (BPV-1) late-specific splice site, and binding of SRp20 to SE4 suppresses this selection. Expression of late BPV-1 L1 or human papillomavirus (HPV) L1, the major capsid protein, inversely correlates with SRp20 levels in the terminally differentiated keratinocytes. In HPV type 16, a similar SRp20-interacting element also controls the viral early-to-late switch. Keratinocytes in raft cultures, which support L1 expression, make considerably less SRp20 than keratinocytes in monolayer cultures, which do not support L1 expression. Conversely, abundant SRp20 in cancer cells or undifferentiated keratinocytes is important for the expression of the viral early E6 and E7 by promoting the expression of cellular transcription factor SP1 for transactivation of viral early promoters.

scholarly journals A Bidirectional SF2/ASF- and SRp40-Dependent Splicing Enhancer Regulates Human Immunodeficiency Virus Type 1 rev, env, vpu, and nef Gene Expression

2004 ◽  
Vol 78 (12) ◽  
pp. 6517-6526 ◽  
Author(s):  
Massimo Caputi ◽  
Marcel Freund ◽  
Susanne Kammler ◽  
Corinna Asang ◽  
Heiner Schaal
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Splice Site ◽  
Immunodeficiency Virus ◽  
U1 Snrnp ◽  
Viral Subtypes ◽  
Splicing Enhancer ◽  
Hiv 1

ABSTRACT The integrated human immunodeficiency virus type 1 (HIV-1) genome is transcribed in a single pre-mRNA that is alternatively spliced into more than 40 mRNAs. We characterized a novel bidirectional exonic splicing enhancer (ESE) that regulates the expression of the HIV-1 env, vpu, rev, and nef mRNAs. The ESE is localized downstream of the vpu-, env-, and nef-specific 3′ splice site no. 5. SF2/ASF and SRp40 activate the ESE and are required for efficient 3′ splice site usage and binding of the U1 snRNP to the downstream 5′ splice site no. 4. U1 snRNP binding to the 5′ splice site no. 4 is required for splicing of the rev and nef mRNAs and to increase expression of the partially spliced env mRNA. Finally, our results indicate that this ESE is necessary for the recruitment of the U1 snRNP to the 5′ splice site no. 4, even when the 5′ splice site and the U1 snRNA have been mutated to obtain a perfect complementary match. The ESE characterized here is highly conserved in most viral subtypes.

scholarly journals Function of a Bovine Papillomavirus Type 1 Exonic Splicing Suppressor Requires a Suboptimal Upstream 3′ Splice Site

1999 ◽  
Vol 73 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Zhi Ming Zheng ◽  
Pei-jun He ◽  
Carl C. Baker
Keyword(s):  
Splice Site ◽  
Bovine Papillomavirus ◽  
Rich Region ◽  
Rous Sarcoma ◽  
Virus Life Cycle ◽  
Immunodeficiency Virus ◽  
Sarcoma Virus ◽  
In Vitro Splicing

ABSTRACT Alternative splicing is an important mechanism for the regulation of bovine papillomavirus type 1 (BPV-1) gene expression during the virus life cycle. Previous studies in our laboratory have identified two purine-rich exonic splicing enhancers (ESEs), SE1 and SE2, located between two alternative 3′ splice sites at nucleotide (nt) 3225 and nt 3605. Further analysis of BPV-1 late-pre-mRNA splicing in vitro revealed a 48-nt pyrimidine-rich region immediately downstream of SE1 that inhibits utilization of the nt 3225 3′ splice site. This inhibitory element, which we named an exonic splicing suppressor (ESS), has a U-rich 5′ end, a C-rich central part, and an AG-rich 3′ end (Z. M. Zheng, P. He, and C. C. Baker, J. Virol. 70:4691–4699, 1996). The present study utilized in vitro splicing of both homologous and heterologous pre-mRNAs to further characterize the ESS. The BPV-1 ESS was inserted downstream of the 3′ splice site in the BPV-1 late pre-mRNA, Rous sarcoma virussrc pre-mRNA, human immunodeficiency virustat-rev pre-mRNA, and Drosophila dsx pre-mRNA, all containing a suboptimal 3′ splice site, and in the human β-globin pre-mRNA, which contains a constitutive 3′ splice site. These studies demonstrated that suppression of splicing by the BPV-1 ESS requires an upstream suboptimal 3′ splice site but not an upstream ESE. Furthermore, the ESS functions when located either upstream or downstream of BPV-1 SE1. Mutational analyses demonstrated that the function of the ESS is sequence dependent and that only the C-rich region of the ESS is essential for suppression of splicing in all the pre-mRNAs tested.

scholarly journals Optimization of a Weak 3′ Splice Site Counteracts the Function of a Bovine Papillomavirus Type 1 Exonic Splicing Suppressor In Vitro and In Vivo

2000 ◽  
Vol 74 (13) ◽  
pp. 5902-5910 ◽  
Author(s):  
Zhi-Ming Zheng ◽  
Jesse Quintero ◽  
Eric S. Reid ◽  
Christian Gocke ◽  
Carl C. Baker
Keyword(s):  
Alternative Splicing ◽  
Splice Site ◽  
Splicing Factors ◽  
Bovine Papillomavirus ◽  
Splicing Pattern ◽  
In Vitro Splicing

ABSTRACT Alternative splicing is a critical component of the early to late switch in papillomavirus gene expression. In bovine papillomavirus type 1 (BPV-1), a switch in 3′ splice site utilization from an early 3′ splice site at nucleotide (nt) 3225 to a late-specific 3′ splice site at nt 3605 is essential for expression of the major capsid (L1) mRNA. Three viral splicing elements have recently been identified between the two alternative 3′ splice sites and have been shown to play an important role in this regulation. A bipartite element lies approximately 30 nt downstream of the nt 3225 3′ splice site and consists of an exonic splicing enhancer (ESE), SE1, followed immediately by a pyrimidine-rich exonic splicing suppressor (ESS). A second ESE (SE2) is located approximately 125 nt downstream of the ESS. We have previously demonstrated that the ESS inhibits use of the suboptimal nt 3225 3′ splice site in vitro through binding of cellular splicing factors. However, these in vitro studies did not address the role of the ESS in the regulation of alternative splicing. In the present study, we have analyzed the role of the ESS in the alternative splicing of a BPV-1 late pre-mRNA in vivo. Mutation or deletion of just the ESS did not significantly change the normal splicing pattern where the nt 3225 3′ splice site is already used predominantly. However, a pre-mRNA containing mutations in SE2 is spliced predominantly using the nt 3605 3′ splice site. In this context, mutation of the ESS restored preferential use of the nt 3225 3′ splice site, indicating that the ESS also functions as a splicing suppressor in vivo. Moreover, optimization of the suboptimal nt 3225 3′ splice site counteracted the in vivo function of the ESS and led to preferential selection of the nt 3225 3′ splice site even in pre-mRNAs with SE2 mutations. In vitro splicing assays also showed that the ESS is unable to suppress splicing of a pre-mRNA with an optimized nt 3225 3′ splice site. These data confirm that the function of the ESS requires a suboptimal upstream 3′ splice site. A surprising finding of our study is the observation that SE1 can stimulate both the first and the second steps of splicing.

scholarly journals Utilization of the Bovine Papillomavirus Type 1 Late-Stage-Specific Nucleotide 3605 3′ Splice Site Is Modulated by a Novel Exonic Bipartite Regulator but Not by an Intronic Purine-Rich Element

2000 ◽  
Vol 74 (22) ◽  
pp. 10612-10622 ◽  
Author(s):  
Zhi-Ming Zheng ◽  
Eric S. Reid ◽  
Carl C. Baker
Keyword(s):  
Life Cycle ◽  
Splice Site ◽  
Late Stage ◽  
Keratinocyte Differentiation ◽  
Bovine Papillomavirus ◽  
Late Gene Expression ◽  
Virus Life Cycle ◽  
Branch Point Sequence

ABSTRACT Bovine papillomavirus type 1 (BPV-1) late gene expression is regulated at both transcriptional and posttranscriptional levels. Maturation of the capsid protein (L1) pre-mRNA requires a switch in 3′ splice site utilization. This switch involves activation of the nucleotide (nt) 3605 3′ splice site, which is utilized only in fully differentiated keratinocytes during late stages of the virus life cycle. Our previous studies of the mechanisms that regulate BPV-1 alternative splicing identified three cis-acting elements between these two splice sites. Two purine-rich exonic splicing enhancers, SE1 and SE2, are essential for preferential utilization of the nt 3225 3′ splice site at early stages of the virus life cycle. Another cis-acting element, exonic splicing suppressor 1 (ESS1), represses use of the nt 3225 3′ splice site. In the present study, we investigated the late-stage-specific nt 3605 3′ splice site and showed that it has suboptimal features characterized by a nonconsensus branch point sequence and a weak polypyrimidine track with interspersed purines. In vitro and in vivo experiments showed that utilization of the nt 3605 3′ splice site was not affected by SE2, which is intronically located with respect to the nt 3605 3′ splice site. The intronic location and sequence composition of SE2 are similar to those of the adenovirus IIIa repressor element, which has been shown to inhibit use of a downstream 3′ splice site. Further studies demonstrated that the nt 3605 3′ splice site is controlled by a novel exonic bipartite element consisting of an AC-rich exonic splicing enhancer (SE4) and an exonic splicing suppressor (ESS2) with a UGGU motif. Functionally, this newly identified bipartite element resembles the bipartite element composed of SE1 and ESS1. SE4 also functions on a heterologous 3′ splice site. In contrast, ESS2 functions as an exonic splicing suppressor only in a 3′-splice-site-specific and enhancer-specific manner. Our data indicate that BPV-1 splicing regulation is very complex and is likely to be controlled by multiple splicing factors during keratinocyte differentiation.

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