| 1. |
- Akusjärvi, Göran, et al.
(författare)
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Messenger RNA in Eukaryotes
- 2007
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Ingår i: Encyclopedia of Life Sciences. - Chichester : John Wiley. - 9780470061411 - 0470061413 ; , s. 1-8
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Posttranscriptional regulation of gene expression represents an important level at which eukaryotes can expand the coding capacity of their genomes. The concept that one gene makes one protein does not apply to higher eukaryotes. Thus, a eukaryotic cell can use alternative ribonucleic acid (RNA) splicing, alternative polyadenylation and RNA editing to produce hundreds or even several thousands of protein isoforms from a single gene.
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| 2. |
- Estmer Nilsson, Camilla, et al.
(författare)
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The adenovirus E4-ORF4 splicing enhancer protein interacts with a subsetof phosphorylated SR proteins
- 2001
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Ingår i: EMBO Journal. - 0261-4189 .- 1460-2075. ; 20, s. 864-871
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Tidskriftsartikel (refereegranskat)abstract
- SR proteins purified from uninfected HeLa cells inhibit adenovirus IIIa pre-mRNA splicing by binding to the intronic IIIa repressor element (3RE). In contrast, SR proteins purified from late adenovirus-infected cells are functionally inactivated as splicing repressor proteins by a virus-induced dephosphorylation. We have shown that the adenovirus E4-ORF4 protein, which binds the cellular protein phos phatase 2A (PP2A) and activates IIIa splicing in vitro and in vivo, induces SR protein dephosphorylation. Here we show that E4-ORF4 interacts with only a subset of SR proteins present in HeLa cells. Thus, E4-ORF4 interacts efficiently with SF2/ASF and SRp30c, but not with other SR proteins. Interestingly, E4-ORF4 interacts with SF2/ASF through the latter's RNA recognition motifs. Furthermore, E4-ORF4 interacts preferentially with the hyperphosphorylated form of SR proteins found in uninfected HeLa cells. E4-ORF4 mutant proteins that fail to bind strongly to PP2A or SF2/ASF do not relieve the repressive effect of HeLa SR proteins on IIIa pre-mRNA splicing in transient transfection experiments, suggesting that an interaction between all three proteins is required for E4-ORF4-induced SR protein dephosphorylation
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| 3. |
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| 4. |
- Kanopka, Arvydas, et al.
(författare)
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Regulation of adenovirus alternative RNAsplicing by dephosphorylation of SR proteins
- 1998
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 393:6681, s. 185-187
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Tidskriftsartikel (refereegranskat)abstract
- SR proteins are a family of essential splicing factors required for early recognition of splice sites during spliceosome assembly. They also function as alternative RNA splicing factors when overexpressed in vivo or added in excess to extracts in vitro. SR proteins are highly phosphorylated in vivo, a modification that is required for their function in spliceosome assembly and splicing catalysis. Here we show that SR proteins purified from late adenovirus-infected cells are inactivated as splicing enhancer or splicing repressor proteins by virus-induced dephosphorylation. We further show that the virus-encoded protein E4-ORF4 activates dephosphorylation by protein phosphatase 2A of HeLa SR proteins and converts their splicing properties into that of SR proteins purified from late adenovirus-infected cells. Taken together, our results suggest that E4-ORF4 is an important factor controlling the temporal shift in adenovirus alternative RNA splicing. We conclude that alternative pre-mRNA splicing, like many other biological processes, is regulated by reversible protein phosphorylation.
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| 5. |
- Mühlemann, Oliver, et al.
(författare)
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A novel type of splicing enhancer regulating adenovirus pre-mRNA splicing
- 2000
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Ingår i: Molecular and Cellular Biology. - 0270-7306 .- 1098-5549. ; 20:7, s. 2317-2325
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Tidskriftsartikel (refereegranskat)abstract
- Splicing of the adenovirus IIIa pre-mRNA is subjected to a temporal regulation, such that efficient IIIa 3' splice site usage is confined to the late phase of the infectious cycle. Here we show that IIIa pre-mRNA splicing is activated more than 200-fold in nuclear extracts prepared from late adenovirus-infected cells (Ad-NE) compared to uninfected HeLa cell nuclear extracts (HeLa-NE). In contrast, splicing of the beta-globin pre-mRNA is repressed in Ad-NE. We constructed hybrid pre-mRNAs between IIIa and beta-globin in order to identify the minimal IIIa sequence element conferring enhanced splicing in Ad-NE. Using this approach, we show that the IIIa branch site/pyrimidine tract functions as a Janus element: it blocks splicing in HeLa-NE and functions as a splicing enhancer in Ad-NE. Therefore, we named this sequence the IIIa virus infection-dependent splicing enhancer (3VDE). This element is essential for regulated IIIa pre-mRNA splicing in Ad-NE and sufficient to confer an enhanced splicing phenotype to the beta-globin pre-mRNA in Ad-NE. We further show that the increase in IIIa splicing observed in Ad-NE is not accompanied by a similar increase in U2AF binding to the IIIa pyrimidine tract. This finding suggests that splicing activation by the 3VDE may operate without efficient U2AF interaction with the pre-mRNA. Importantly, this report represents the first description of a splicing enhancer that has evolved to function selectively in the context of a virus infection, a finding that adds a new level at which viruses may subvert the host cell RNA biosynthetic machinery to facilitate their own replication.
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| 6. |
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| 7. |
- Petersen-Mahrt, Svend K, et al.
(författare)
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The splicing factor-associated protein, p32, regulates RNA splicing byinhibiting ASF/SF2 RNA binding and phosphorylation
- 1999
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Ingår i: EMBO Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 18:4, s. 1014-1024
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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