| 41. |
- Kanopka, Arvydas, et al.
(författare)
-
Inhibition by SRproteins of splicing of a regulated adenovirus pre-mRNA
- 1996
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 381, s. 535-538
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Tidskriftsartikel (refereegranskat)abstract
- The adenovirus L1 unit represents an example of an alternatively spliced precursor messenger (pre-mRNA) where on 5' splice can be jointed to one of two alternative 3' splice sites, producing the 52,55K or the IIIa mRNAs (Fig. 1a). Efficient usage of the distal IIIa 3' splice site requires late viral protein synthesis and is therefore confined to the late phase of virus infection. Here we show that, in extracts from uninfected cells, the classical SR proteins, which are essential splicing factors, inhibit IIIa pre-mRNA splicing by binding to an intronic repressor element and preventing recruitment of the U2 small nuclear ribonucleoprotein particle to the spliceosome. We further show that the viral repressor element has splicing-enhancer activity when appropriately placed in the pre-mRNA. Together, our results demonstrate that SR proteins function as activators or repressors of splicing depending on where on the pre-mRNA they bind.
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| 42. |
- Kanopka, Arvydas, et al.
(författare)
-
Regulation of adenovirus alternative RNAsplicing by dephosphorylation of SR proteins
- 1998
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 393:6681, s. 185-187
-
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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| 43. |
- Karre, K, et al.
(författare)
-
Viral decoy vetoes killer cell
- 1997
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 386:6624, s. 446-447
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 44. |
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| 45. |
- Klein, G, et al.
(författare)
-
Immunology. Sinking surveillance's flagship
- 1998
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 395:6701, s. 441-
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 46. |
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| 47. |
- Klein, G
(författare)
-
The tale of the great cuckoo egg
- 1999
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 400:6744, s. 515-515
-
Tidskriftsartikel (refereegranskat)
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| 48. |
- Kurokawa, R., et al.
(författare)
-
Polarity-specific activities of retinoic acid receptors determined by a co-repressor.
- 1995
-
Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 377:6548, s. 451-454
-
Tidskriftsartikel (refereegranskat)abstract
- Retinoic acid receptors (RARs) and retinoid-X receptors (RXRs) activate or repress transcription by binding as heterodimers to DNA-response elements that generally consist of two direct repeat half-sites of consensus sequence AGGTCA. On response elements consisting of direct repeats spaced by five base pairs (DR + 5 elements), RAR/RXR heterodimers activate transcription in response to RAR-specific ligands, such as all-trans-retinoic acid (RA). In contrast, on elements consisting of direct repeats spaced by one base pair (DR + 1 elements), RAR/RXR heterodimers exhibit little or no response to activating ligands and repress RXR-dependent transcription. Here we show that ligand-dependent transactivation by RAR on DR + 5 elements requires the dissociation of a new nuclear receptor co-repressor, N-CoR, and recruitment of the putative co-activators p140 and p160. Surprisingly, on DR + 1 elements, N-CoR remains associated with RAR/RXR heterodimers even in the presence of RAR ligands, resulting in constitutive repression. These observations indicate that DNA-response elements can allosterically regulate RAR-co-repressor interactions to determine positive or negative regulation of gene expression.
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| 49. |
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| 50. |
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