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Zhiming Zheng - One of the best experts on this subject based on the ideXlab platform.
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serine arginine rich Splicing factor 3 and heterogeneous nuclear ribonucleoprotein a1 regulate alteRNAtive RNA Splicing and gene expression of human papillomavirus 18 through two functionally distinguishable cis elements
Journal of Virology, 2016Co-Authors: Masahiko Ajiro, Shuang Tang, John Doorbar, Zhiming ZhengAbstract:UNLABELLED: Human papillomavirus 18 (HPV18) is the second most common oncogenic HPV type associated with cervical, anogenital, and oropharyngeal cancers. Like other oncogenic HPVs, HPV18 encodes two major (one early and one late) polycistronic pre-mRNAs that are regulated by alteRNAtive RNA Splicing to produce a repertoire of viral transcripts for the expression of individual viral genes. However, RNA cis-regulatory elements and trans-acting factors contributing to HPV18 alteRNAtive RNA Splicing remain unknown. In this study, an exonic Splicing enhancer (ESE) in the nucleotide (nt) 3520 to 3550 region in the HPV18 genome was identified and characterized for promotion of HPV18 929^3434 Splicing and E1^E4 production through interaction with SRSF3, a host oncogenic Splicing factor differentially expressed in epithelial cells and keratinocytes. Introduction of point mutations in the SRSF3-binding site or knockdown of SRSF3 expression in cells reduces 929^3434 Splicing and E1^E4 production but activates other, minor 929^3465 and 929^3506 Splicing. Knockdown of SRSF3 expression also enhances the expression of E2 and L1 mRNAs. An exonic Splicing silencer (ESS) in the HPV18 nt 612 to 639 region was identified as being inhibitory to the 233^416 Splicing of HPV18 E6E7 pre-mRNAs via binding to hnRNP A1, a well-characterized, abundantly and ubiquitously expressed RNA-binding protein. Introduction of point mutations into the hnRNP A1-binding site or knockdown of hnRNP A1 expression promoted 233^416 Splicing and reduced E6 expression. These data provide the first evidence that the alteRNAtive RNA Splicing of HPV18 pre-mRNAs is subject to regulation by viral RNA cis elements and host trans-acting Splicing factors. IMPORTANCE: Expression of HPV18 genes is regulated by alteRNAtive RNA Splicing of viral polycistronic pre-mRNAs to produce a repertoire of viral early and late transcripts. RNA cis elements and trans-acting factors contributing to HPV18 alteRNAtive RNA Splicing have been discovered in this study for the first time. The identified ESS at the E7 open reading frame (ORF) prevents HPV18 233^416 Splicing in the E6 ORF through interaction with a host Splicing factor, hnRNP A1, and regulates E6 and E7 expression of the early E6E7 polycistronic pre-mRNA. The identified ESE at the E1^E4 ORF promotes HPV18 929^3434 Splicing of both viral early and late pre-mRNAs and E1^E4 production through interaction with SRSF3. This study provides important observations on how alteRNAtive RNA Splicing of HPV18 pre-mRNAs is subject to regulation by viral RNA cis elements and host Splicing factors and offers potential therapeutic targets to overcome HPV-related cancer.
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serine arginine rich Splicing factor 3 and heterogeneous nuclear ribonucleoprotein a1 regulate alteRNAtive RNA Splicing and gene expression of human papillomavirus 18 through two functionally distinguishable cis elements
Journal of Virology, 2016Co-Authors: Masahiko Ajiro, Shuang Tang, John Doorbar, Zhiming ZhengAbstract:UNLABELLED: Human papillomavirus 18 (HPV18) is the second most common oncogenic HPV type associated with cervical, anogenital, and oropharyngeal cancers. Like other oncogenic HPVs, HPV18 encodes two major (one early and one late) polycistronic pre-mRNAs that are regulated by alteRNAtive RNA Splicing to produce a repertoire of viral transcripts for the expression of individual viral genes. However, RNA cis-regulatory elements and trans-acting factors contributing to HPV18 alteRNAtive RNA Splicing remain unknown. In this study, an exonic Splicing enhancer (ESE) in the nucleotide (nt) 3520 to 3550 region in the HPV18 genome was identified and characterized for promotion of HPV18 929^3434 Splicing and E1^E4 production through interaction with SRSF3, a host oncogenic Splicing factor differentially expressed in epithelial cells and keratinocytes. Introduction of point mutations in the SRSF3-binding site or knockdown of SRSF3 expression in cells reduces 929^3434 Splicing and E1^E4 production but activates other, minor 929^3465 and 929^3506 Splicing. Knockdown of SRSF3 expression also enhances the expression of E2 and L1 mRNAs. An exonic Splicing silencer (ESS) in the HPV18 nt 612 to 639 region was identified as being inhibitory to the 233^416 Splicing of HPV18 E6E7 pre-mRNAs via binding to hnRNP A1, a well-characterized, abundantly and ubiquitously expressed RNA-binding protein. Introduction of point mutations into the hnRNP A1-binding site or knockdown of hnRNP A1 expression promoted 233^416 Splicing and reduced E6 expression. These data provide the first evidence that the alteRNAtive RNA Splicing of HPV18 pre-mRNAs is subject to regulation by viral RNA cis elements and host trans-acting Splicing factors. IMPORTANCE: Expression of HPV18 genes is regulated by alteRNAtive RNA Splicing of viral polycistronic pre-mRNAs to produce a repertoire of viral early and late transcripts. RNA cis elements and trans-acting factors contributing to HPV18 alteRNAtive RNA Splicing have been discovered in this study for the first time. The identified ESS at the E7 open reading frame (ORF) prevents HPV18 233^416 Splicing in the E6 ORF through interaction with a host Splicing factor, hnRNP A1, and regulates E6 and E7 expression of the early E6E7 polycistronic pre-mRNA. The identified ESE at the E1^E4 ORF promotes HPV18 929^3434 Splicing of both viral early and late pre-mRNAs and E1^E4 production through interaction with SRSF3. This study provides important observations on how alteRNAtive RNA Splicing of HPV18 pre-mRNAs is subject to regulation by viral RNA cis elements and host Splicing factors and offers potential therapeutic targets to overcome HPV-related cancer.
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kaposi s sarcoma associated herpesvirus orf57 functions as a viral Splicing factor and promotes expression of intron containing viral lytic genes in spliceosome mediated RNA Splicing
Journal of Virology, 2008Co-Authors: Vladimir Majerciak, Koji Yamanegi, Eric Allemand, Michael J Kruhlak, Adrian R Krainer, Zhiming ZhengAbstract:Kaposi's sarcoma-associated herpesvirus (KSHV) ORF57 facilitates the expression of both intronless viral ORF59 genes and intron-containing viral K8 and K8.1 genes (V. Majerciak, N. Pripuzova, J. P. McCoy, S. J. Gao, and Z. M. Zheng, J. Virol. 81:1062-1071, 2007). In this study, we showed that disruption of ORF57 in a KSHV genome led to increased accumulation of ORF50 and K8 pre-mRNAs and reduced expression of ORF50 and K-bZIP proteins but had no effect on latency-associated nuclear antigen (LANA). Cotransfection of ORF57 and K8β cDNA, which retains a suboptimal intron of K8 pre-mRNA due to alteRNAtive Splicing, promoted RNA Splicing of K8β and production of K8α (K-bZIP). Although Epstein-Barr virus EB2, a closely related homolog of ORF57, had a similar activity in the cotransfection assays, herpes simplex virus type 1 ICP27 was inactive. This enhancement of RNA Splicing by ORF57 correlates with the intact N-terminal nuclear localization signal motifs of ORF57 and takes place in the absence of other viral proteins. In activated KSHV-infected B cells, KSHV ORF57 partially colocalizes with Splicing factors in nuclear speckles and assembles into spliceosomal complexes in association with low-abundance viral ORF50 and K8 pre-mRNAs and essential Splicing components. The association of ORF57 with snRNAs occurs by ORF57-Sm protein interaction. We also found that ORF57 binds K8β pre-mRNAs in vitro in the presence of nuclear extracts. Collectively our data indicate that KSHV ORF57 functions as a novel Splicing factor in the spliceosome-mediated Splicing of viral RNA transcripts.
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Regulation of alteRNAtive RNA Splicing by exon definition and exon sequences in viral and mammalian gene expression
Journal of Biomedical Science, 2004Co-Authors: Zhiming ZhengAbstract:Intron removal from a pre-mRNA by RNA Splicing was once thought to be controlled mainly by intron Splicing signals. However, viral and other eukaryotic RNA exon sequences have recently been found to regulate RNA Splicing, polyadenylation, export, and nonsense-mediated RNA decay in addition to their coding function. Regulation of alteRNAtive RNA Splicing by exon sequences is largely attributable to the presence of two major cis -acting elements in the regulated exons, the exonic Splicing enhancer (ESE) and the suppressor or silencer (ESS). Two types of ESEs have been verified from more than 50 genes or exons: purine-rich ESEs, which are the more common, and non-purine-rich ESEs. In contrast, the sequences of ESSs identified in approximately 20 genes or exons are highly diverse and show little similarity to each other. Through interactions with cellular Splicing factors, an ESE or ESS determines whether or not a regulated splice site, usually an upstream 3′ splice site, will be used for RNA Splicing. However, how these elements function precisely in selecting a regulated splice site is only partially understood. The balance between positive and negative regulation of splice site selection likely depends on the cis -element's identity and changes in cellular Splicing factors under physiological or pathological conditions.
Göran Akusjärvi - One of the best experts on this subject based on the ideXlab platform.
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Review Regulation of Human Adenovirus AlteRNAtive RNA Splicing by the Adenoviral L4-33K and L4-22K Proteins
2016Co-Authors: Roberta Biasiotto, Göran AkusjärviAbstract:Abstract: Adenovirus makes extensive use of alteRNAtive RNA Splicing to produce a complex set of spliced viral mRNAs. Studies aimed at characterizing the interactions between the virus and the host cell RNA Splicing machinery have identified three viral proteins of special significance for the control of late viral gene expression: L4-33K, L4-22K, and E4-ORF4. L4-33K is a viral alteRNAtive RNA Splicing factor that controls L1 alteRNAtive Splicing via an interaction with the cellular protein kinases Protein Kinase A (PKA) and DNA-dependent protein kinase (DNA-PK). L4-22K is a viral transcription factor that also has been implicated in the Splicing of a subset of late viral mRNAs. E4-ORF4 is a viral protein that binds the cellular protein phosphatase IIA (PP2A) and controls Serine/Arginine (SR)-rich protein activity by inducing SR protein dephosphorylation. The L4-33K, and most likely also the L4-22K protein, are highly phosphorylated in vivo. Here we will review the function of these viral proteins in the post-transcriptional control of adenoviral gene expression and further discuss the significance of potential protein kinases phosphorylating the L4-33K and/or L4-22K proteins
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Regulation of Human Adenovirus AlteRNAtive RNA Splicing by the Adenoviral L4-33K and L4-22K Proteins
International Journal of Molecular Sciences, 2015Co-Authors: Roberta Biasiotto, Göran AkusjärviAbstract:Adenovirus makes extensive use of alteRNAtive RNA Splicing to produce a complex set of spliced viral mRNAs. Studies aimed at characterizing the interactions between the virus and the host cell RNA Splicing machinery have identified three viral proteins of special significance for the control of late viral gene expression: L4-33K, L4-22K, and E4-ORF4. L4-33K is a viral alteRNAtive RNA Splicing factor that controls L1 alteRNAtive Splicing via an interaction with the cellular protein kinases Protein Kinase A (PKA) and DNA-dependent protein kinase (DNA-PK). L4-22K is a viral transcription factor that also has been implicated in the Splicing of a subset of late viral mRNAs. E4-ORF4 is a viral protein that binds the cellular protein phosphatase IIA (PP2A) and controls Serine/Arginine (SR)-rich protein activity by inducing SR protein dephosphorylation. The L4-33K, and most likely also the L4-22K protein, are highly phosphorylated in vivo. Here we will review the function of these viral proteins in the post-transcriptional control of adenoviral gene expression and further discuss the significance of potential protein kinases phosphorylating the L4-33K and/or L4-22K proteins.
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Two Cellular Protein Kinases, DNA-PK and PKA, Phosphorylate the Adenoviral L4-33K Protein and Have Opposite Effects on L1 AlteRNAtive RNA Splicing
PLOS ONE, 2012Co-Authors: Heidi Törmänen Persson, Anne Kristin Aksaas, Anne-katrine Kvissel, Bjørn Steen Skålhegg, Ake Engstrom, Tanel Punga, Göran AkusjärviAbstract:Accumulation of the complex set of alteRNAtively processed mRNA from the adenovirus major late transcription unit (MLTU) is subjected to a temporal regulation involving both changes in poly (A) site choice and alteRNAtive 3′ splice site usage. We have previously shown that the adenovirus L4-33K protein functions as an alteRNAtive Splicing factor involved in activating the shift from L1-52,55K to L1-IIIa mRNA. Here we show that L4-33K specifically associates with the catalytic subunit of the DNA-dependent protein kinase (DNA-PK) in uninfected and adenovirus-infected nuclear extracts. Further, we show that L4-33K is highly phosphorylated by DNA-PK in vitro in a double stranded DNA-independent manner. Importantly, DNA-PK deficient cells show an enhanced production of the L1-IIIa mRNA suggesting an inhibitory role of DNA-PK on the temporal switch in L1 alteRNAtive RNA Splicing. Moreover, we show that L4-33K also is phosphorylated by protein kinase A (PKA), and that PKA has an enhancer effect on L4-33K-stimulated L1-IIIa Splicing. Hence, we demonstrate that these kinases have opposite effects on L4-33K function; DNA-PK as an inhibitor and PKA as an activator of L1-IIIa mRNA Splicing. Taken together, this is the first report identifying protein kinases that phosphorylate L4-33K and to suggest novel regulatory roles for DNA-PK and PKA in adenovirus alteRNAtive RNA Splicing.
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L4-33K, an Adenovirus-encoded AlteRNAtive RNA Splicing Factor
Journal of Biological Chemistry, 2006Co-Authors: Heidi Törmänen, Ellenor Backström, Anette Carlsson, Göran AkusjärviAbstract:Splicing of the adenovirus IIIa mRNA is subjected to a strict temporal regulation during virus infection such that efficient IIIa 3' splice site usage is confined to the late phase of the infectious cycle. Here we show that the adenovirus L4-33K protein functions as a virus-encoded RNA Splicing factor that preferentially activates Splicing of transcripts with a weak 3' splice site sequence context, a sequence configuration that is shared by many of the late adenovirus 3' splice sites. Furthermore, we show that L4-33K activates IIIa Splicing through the IIIa virus infection-dependent Splicing enhancer element (3VDE). This element was previously shown to be the minimal element, both necessary and sufficient, for activation of IIIa Splicing in the context of an adenovirus-infected cell. L4-33K stimulates an early step in spliceosome assembly and appears to be the only viral protein necessary to convert a nuclear extract prepared from uninfected HeLa cells to an extract with Splicing properties very similar to a nuclear extract prepared from adenovirus late-infected cells. Collectively, our results suggest that L4-33K is the key viral protein required to activate the early to late switch in adenovirus major late L1 alteRNAtive Splicing.
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the Splicing factor associated protein p32 regulates RNA Splicing by inhibiting asf sf2 RNA binding and phosphorylation
The EMBO Journal, 1999Co-Authors: Svend K Petersenmahrt, Camilla Estmer, W. C. Russell, David A. Matthews, Christina Ohrmalm, Göran AkusjärviAbstract:The cellular protein p32 was isolated originally as a protein tightly associated with the essential Splicing factor ASF/SF2 during its purification from HeLa cells. ASF/SF2 is a member of the SR family of Splicing factors, which stimulate constitutive Splicing and regulate alteRNAtive RNA Splicing in a positive or negative fashion, depending on where on the pre-mRNA they bind. Here we present evidence that p32 interacts with ASF/SF2 and SRp30c, another member of the SR protein family. We further show that p32 inhibits ASF/SF2 function as both a Splicing enhancer and Splicing repressor protein by preventing stable ASF/SF2 interaction with RNA, but p32 does not block SRp30c function. ASF/SF2 is highly phosphorylated in vivo, a modification required for stable RNA binding and protein-protein interaction during spliceosome formation, and this phosphorylation, either through HeLa nuclear extracts or through specific SR protein kinases, is inhibited by p32. Our results suggest that p32 functions as an ASF/SF2 inhibitory factor, regulating ASF/SF2 RNA binding and phosphorylation. These findings place p32 into a new group of proteins that control RNA Splicing by sequestering an essential RNA Splicing factor into an inhibitory complex.
Masahiko Ajiro - One of the best experts on this subject based on the ideXlab platform.
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serine arginine rich Splicing factor 3 and heterogeneous nuclear ribonucleoprotein a1 regulate alteRNAtive RNA Splicing and gene expression of human papillomavirus 18 through two functionally distinguishable cis elements
Journal of Virology, 2016Co-Authors: Masahiko Ajiro, Shuang Tang, John Doorbar, Zhiming ZhengAbstract:UNLABELLED: Human papillomavirus 18 (HPV18) is the second most common oncogenic HPV type associated with cervical, anogenital, and oropharyngeal cancers. Like other oncogenic HPVs, HPV18 encodes two major (one early and one late) polycistronic pre-mRNAs that are regulated by alteRNAtive RNA Splicing to produce a repertoire of viral transcripts for the expression of individual viral genes. However, RNA cis-regulatory elements and trans-acting factors contributing to HPV18 alteRNAtive RNA Splicing remain unknown. In this study, an exonic Splicing enhancer (ESE) in the nucleotide (nt) 3520 to 3550 region in the HPV18 genome was identified and characterized for promotion of HPV18 929^3434 Splicing and E1^E4 production through interaction with SRSF3, a host oncogenic Splicing factor differentially expressed in epithelial cells and keratinocytes. Introduction of point mutations in the SRSF3-binding site or knockdown of SRSF3 expression in cells reduces 929^3434 Splicing and E1^E4 production but activates other, minor 929^3465 and 929^3506 Splicing. Knockdown of SRSF3 expression also enhances the expression of E2 and L1 mRNAs. An exonic Splicing silencer (ESS) in the HPV18 nt 612 to 639 region was identified as being inhibitory to the 233^416 Splicing of HPV18 E6E7 pre-mRNAs via binding to hnRNP A1, a well-characterized, abundantly and ubiquitously expressed RNA-binding protein. Introduction of point mutations into the hnRNP A1-binding site or knockdown of hnRNP A1 expression promoted 233^416 Splicing and reduced E6 expression. These data provide the first evidence that the alteRNAtive RNA Splicing of HPV18 pre-mRNAs is subject to regulation by viral RNA cis elements and host trans-acting Splicing factors. IMPORTANCE: Expression of HPV18 genes is regulated by alteRNAtive RNA Splicing of viral polycistronic pre-mRNAs to produce a repertoire of viral early and late transcripts. RNA cis elements and trans-acting factors contributing to HPV18 alteRNAtive RNA Splicing have been discovered in this study for the first time. The identified ESS at the E7 open reading frame (ORF) prevents HPV18 233^416 Splicing in the E6 ORF through interaction with a host Splicing factor, hnRNP A1, and regulates E6 and E7 expression of the early E6E7 polycistronic pre-mRNA. The identified ESE at the E1^E4 ORF promotes HPV18 929^3434 Splicing of both viral early and late pre-mRNAs and E1^E4 production through interaction with SRSF3. This study provides important observations on how alteRNAtive RNA Splicing of HPV18 pre-mRNAs is subject to regulation by viral RNA cis elements and host Splicing factors and offers potential therapeutic targets to overcome HPV-related cancer.
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serine arginine rich Splicing factor 3 and heterogeneous nuclear ribonucleoprotein a1 regulate alteRNAtive RNA Splicing and gene expression of human papillomavirus 18 through two functionally distinguishable cis elements
Journal of Virology, 2016Co-Authors: Masahiko Ajiro, Shuang Tang, John Doorbar, Zhiming ZhengAbstract:UNLABELLED: Human papillomavirus 18 (HPV18) is the second most common oncogenic HPV type associated with cervical, anogenital, and oropharyngeal cancers. Like other oncogenic HPVs, HPV18 encodes two major (one early and one late) polycistronic pre-mRNAs that are regulated by alteRNAtive RNA Splicing to produce a repertoire of viral transcripts for the expression of individual viral genes. However, RNA cis-regulatory elements and trans-acting factors contributing to HPV18 alteRNAtive RNA Splicing remain unknown. In this study, an exonic Splicing enhancer (ESE) in the nucleotide (nt) 3520 to 3550 region in the HPV18 genome was identified and characterized for promotion of HPV18 929^3434 Splicing and E1^E4 production through interaction with SRSF3, a host oncogenic Splicing factor differentially expressed in epithelial cells and keratinocytes. Introduction of point mutations in the SRSF3-binding site or knockdown of SRSF3 expression in cells reduces 929^3434 Splicing and E1^E4 production but activates other, minor 929^3465 and 929^3506 Splicing. Knockdown of SRSF3 expression also enhances the expression of E2 and L1 mRNAs. An exonic Splicing silencer (ESS) in the HPV18 nt 612 to 639 region was identified as being inhibitory to the 233^416 Splicing of HPV18 E6E7 pre-mRNAs via binding to hnRNP A1, a well-characterized, abundantly and ubiquitously expressed RNA-binding protein. Introduction of point mutations into the hnRNP A1-binding site or knockdown of hnRNP A1 expression promoted 233^416 Splicing and reduced E6 expression. These data provide the first evidence that the alteRNAtive RNA Splicing of HPV18 pre-mRNAs is subject to regulation by viral RNA cis elements and host trans-acting Splicing factors. IMPORTANCE: Expression of HPV18 genes is regulated by alteRNAtive RNA Splicing of viral polycistronic pre-mRNAs to produce a repertoire of viral early and late transcripts. RNA cis elements and trans-acting factors contributing to HPV18 alteRNAtive RNA Splicing have been discovered in this study for the first time. The identified ESS at the E7 open reading frame (ORF) prevents HPV18 233^416 Splicing in the E6 ORF through interaction with a host Splicing factor, hnRNP A1, and regulates E6 and E7 expression of the early E6E7 polycistronic pre-mRNA. The identified ESE at the E1^E4 ORF promotes HPV18 929^3434 Splicing of both viral early and late pre-mRNAs and E1^E4 production through interaction with SRSF3. This study provides important observations on how alteRNAtive RNA Splicing of HPV18 pre-mRNAs is subject to regulation by viral RNA cis elements and host Splicing factors and offers potential therapeutic targets to overcome HPV-related cancer.
Xuesen Dong - One of the best experts on this subject based on the ideXlab platform.
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AlteRNAtive RNA Splicing of the GIT1 gene is associated with neuroendocrine prostate cancer
Cancer Science, 2018Co-Authors: Varune Rohan Ramnarine, Jessica M. Lovnicki, Xuesen DongAbstract:: Potent androgen receptor pathway inhibition (ARPI) therapies have given rise to a lethal, aggressive subtype of castration-resistant prostate cancer (CRPC) called treatment-induced neuroendocrine prostate cancer (t-NEPC). Now, t-NEPC poses a major clinical problem as approximately 20% of CRPC cases bear this subtype-a rate of occurrence that is predicted to rise with the widespread use of ARPI therapies. Unfortunately, there are no targeted therapies currently available to treat t-NEPC as the origin and molecular underpinnings of t-NEPC development remain unclear. In the present study, we identify that RNA Splicing of the G protein-coupled receptor kinase-interacting protein 1 (GIT1) gene is a unique event in t-NEPC patients. Specifically, upregulation of the GIT1-A splice variant and downregulation of the GIT1-C variant expressions are associated with t-NEPC patient tumors, patient-derived xenografts, and cell models. RNA-binding assays show that RNA Splicing of GIT1 is directly driven by SRRM4 and is associated with the neuroendocrine phenotype in CRPC cohorts. We show that GIT1-A and GIT1-C regulate differential transcriptomes in prostate cancer cells, where GIT1-A regulates genes associated with morphogenesis, neural function, environmental sensing via cell-adhesion processes, and epigenetic regulation. Consistent with our transcriptomic analyses, we report opposing functions of GIT1-A and GIT1-C in the stability of focal adhesions, whereby GIT1-A promotes focal adhesion stability. In summary, our study is the first to report that alteRNAtive RNA Splicing of the GIT1 gene is associated with t-NEPC and reprograms its function involving FA-mediated signaling and cell processes, which may contribute to t-NEPC development.
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Establishment of a neuroendocrine prostate cancer model driven by the RNA Splicing factor SRRM4
Oncotarget, 2017Co-Authors: Ruiqi Chen, Colin Collins, Martin E Gleave, Mary Bowden, Yen-yi Lin, Xuesen DongAbstract:// Yinan Li 1 , Ruiqi Chen 1 , Mary Bowden 1 , Fan Mo 1 , Yen-Yi Lin 1 , Martin Gleave 1 , Colin Collins 1 and Xuesen Dong 1 1 Department of Urologic Sciences, Vancouver Prostate Centre, The University of British Columbia, Vancouver, Canada Correspondence to: Xuesen Dong, email: // Keywords : neuroendocrine prostate cancer, cell/tumor models, SRRM4, RNA Splicing Received : June 30, 2017 Accepted : July 06, 2017 Published : August 03, 2017 Abstract Neuroendocrine prostate cancer (NEPC) is becoming more prevalent as more potent androgen receptor (AR) pathway inhibitors are applied to patients with metastatic tumors. However, there are limited cell and xenograft models currently available, hindering the investigation of signal pathways involved in regulating NEPC progression and the design of high throughput screening assays for inhibitors to treat NEPC patients. Here, we report an NEPC model, LnNE, that is derived from prostate adenocarcinoma cells and has global similarity in transcription and RNA Splicing to tumors from NEPC patients. LnNE xenografts are castrate-resistant and highly aggressive. Its tumor take is ~3-5 weeks and tumor doubling time is ~2-3 weeks. LnNE expresses multiple neuroendocrine markers, preserves AR expression, but is PSA negative. Its neuroendocrine phenotype cannot be reversed by androgen treatment. LnNE cells grow as multi-cellular spheroids under 2-dimensional culture conditions similar to the NEPC cell line NCI-H660, but have higher proliferation rate and are easier to be transfected. LnNE cells can also adapt to 3-dimensional culture conditions in a 96-plate format, allowing high throughput screening assays. In summary, the LnNE model is useful to study the mechanisms of NEPC progression and to discover potential therapies for NEPC.
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consensus pp1 binding motifs regulate transcriptional corepression and alteRNAtive RNA Splicing activities of the steroid receptor coregulators p54nrb and psf
Molecular Endocrinology, 2011Co-Authors: Liangliang Liu, Martin E Gleave, Paul S. Rennie, Stephen J. Lye, Ning Xie, John R G Challis, Xuesen DongAbstract:Originally identified as essential pre-mRNA Splicing factors, non-POU-domain-containing, octamer binding protein (p54nrb) and PTB-associated RNA Splicing factor (PSF) are also steroid receptor corepressors. The mechanisms by which p54nrb and PSF regulate gene transcription remain unclear. Both p54nrb and PSF contain protein phosphatase 1 (PP1) consensus binding RVxF motifs, suggesting that PP1 may regulate phosphorylation status of p54nrb and PSF and thus their function in gene transcription. In this report, we demonstrated that PP1 forms a protein complex with both p54nrb and PSF. PP1 interacts directly with the RVxF motif only in p54nrb, but not in PSF. Association with PP1 results in dephosphorylation of both p54nrb and PSF in vivo and the loss of their transcriptional corepressor activities. Using the CD44 minigene as a reporter, we showed that PP1 regulates p54nrb and PSF alteRNAtive Splicing activities that determine exon skipping vs. inclusion in the final mature RNA for translation. In addition, changes in transcriptional corepression and RNA Splicing activities of p54nrb and PSF are correlated with alterations in protein interactions of p54nrb and PSF with transcriptional corepressors such as Sin3A and histone deacetylase 1, and RNA Splicing factors such as U1A and U2AF. Furthermore, we demonstrated a novel function of the RVxF motif within PSF that enhances its corepression and RNA Splicing activities independent of PP1. We conclude that the RVxF motifs play an important role in controlling the multifunctional properties of p54nrb and PSF in the regulation of gene transcription.
Rui Zhou - One of the best experts on this subject based on the ideXlab platform.
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concerted effects of heterogeneous nuclear ribonucleoprotein c1 c2 to control vitamin d directed gene transcription and RNA Splicing in human bone cells
Nucleic Acids Research, 2017Co-Authors: Rui Zhou, Juw Won Park, Rene F Chun, Thomas S Lisse, Alejandro J Garcia, Kathryn Zavala, Jessica L Sea, John S Adams, Yi XingAbstract:Traditionally recognized as an RNA Splicing regulator, heterogeneous nuclear ribonucleoprotein C1/C2 (hnRNPC1/C2) can also bind to double-stranded DNA and function in trans as a vitamin D response element (VDRE)-binding protein. As such, hnRNPC1/C2 may couple transcription induced by the active form of vitamin D, 1,25-dihydroxyvitamin D (1,25(OH)2D) with subsequent RNA Splicing. In MG63 osteoblastic cells, increased expression of the 1,25(OH)2D target gene CYP24A1 involved immunoprecipitation of hnRNPC1/C2 with CYP24A1 chromatin and RNA. Knockdown of hnRNPC1/C2 suppressed expression of CYP24A1, but also increased expression of an exon 10-skipped CYP24A1 splice variant; in a minigene model the latter was attenuated by a functional VDRE in the CYP24A1 promoter. In genome-wide analyses, knockdown of hnRNPC1/C2 resulted in 3500 differentially expressed genes and 2232 differentially spliced genes, with significant commonality between groups. 1,25(OH)2D induced 324 differentially expressed genes, with 187 also observed following hnRNPC1/C2 knockdown, and a further 168 unique to hnRNPC1/C2 knockdown. However, 1,25(OH)2D induced only 10 differentially spliced genes, with no overlap with differentially expressed genes. These data indicate that hnRNPC1/C2 binds to both DNA and RNA and influences both gene expression and RNA Splicing, but these actions do not appear to be linked through 1,25(OH)2D-mediated induction of transcription.
