An Evolutionarily Conserved Role for SRm160 in 3â²-End Processing That Functions Independently of Exon Junction Complex Formation
SRm160 (the SR -related nuclear m atrix protein of 160 kDa) functions as a splicing coactivator and 3â²-end cleavage-stimulatory factor. It is also a component of the splicing-dependent exon-junction complex (EJC), which has been implicated in coupling of pre-mRNA splicing with mRNA turnover and mR...
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Published in | The Journal of biological chemistry Vol. 278; no. 45; p. 44153 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
American Society for Biochemistry and Molecular Biology
07.11.2003
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Online Access | Get full text |
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Summary: | SRm160 (the SR -related nuclear m atrix protein of 160 kDa) functions as a splicing coactivator and 3â²-end cleavage-stimulatory factor. It is also a component of the splicing-dependent
exon-junction complex (EJC), which has been implicated in coupling of pre-mRNA splicing with mRNA turnover and mRNA export.
We have investigated whether the association of SRm160 with the EJC is important for efficient 3â²-end cleavage. The EJC components
RNPS1, REF, UAP56, and Y14 interact with SRm160. However, when these factors were tethered to transcripts, only SRm160 and
RNPS1 stimulated 3â²-end cleavage. Whereas SRm160 stimulated cleavage to a similar extent in the presence or absence of an
active intron, stimulation of 3â²-end cleavage by tethered RNPS1 is dependent on an active intron. Assembly of an EJC adjacent
to the cleavage and polyadenylation signal in vitro did not significantly affect cleavage efficiency. These results suggest that SRm160 stimulates cleavage independently of
its association with EJC components and that the cleavage-stimulatory activity of RNPS1 may be an indirect consequence of
its ability to stimulate splicing. Using RNA interference (RNAi) in Caenorhabditis elegans , we determined whether interactions between SRm160 and the cleavage machinery are important in a whole organism context.
Simultaneous RNAi of SRm160 and the cleavage factor CstF-50 ( C leavage s timulation f actor 50 -kDa subunit) resulted in late embryonic developmental arrest. In contrast, RNAi of CstF-50 in combination with RNPS1 or REFs
did not result in an apparent phenotype. Our combined results provide evidence for an evolutionarily conserved interaction
between SRm160 and the 3â²-end cleavage machinery that functions independently of EJC formation. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.M306856200 |