The SRm160/300 splicing coactivator is required for exon-enhancer function.
Exonic splicing enhancer (ESE) sequences are important for the recognition of splice sites in pre-mRNA. These sequences are bound by specific serine-arginine (SR) repeat proteins that promote the assembly of splicing complexes at adjacent splice sites. We have recently identified a splicing "coactivator," SRm160/300, which contains SRm160 (the SR nuclear matrix protein of 160 kDa) and a 300-kDa nuclear matrix antigen. In the present study, we show that SRm160/300 is required for a purine-rich ESE to promote the splicing of a pre-mRNA derived from the Drosophila doublesex gene. The association of SRm160/300 and U2 small nuclear ribonucleoprotein particle (snRNP) with this pre-mRNA requires both U1 snRNP and factors bound to the ESE. Independently of pre-mRNA, SRm160/300 specifically interacts with U2 snRNP and with a human homolog of the Drosophila alternative splicing regulator Transformer 2, which binds to purine-rich ESEs. The results suggest a model for ESE function in which the SRm160/300 splicing coactivator promotes critical interactions between ESE-bound "activators" and the snRNP machinery of the spliceosome.
Eldridge
A G
AG
Banting and Best Department of Medical Research, University of Toronto, Toronto, ON M5G 1L6, Canada.
Li
Y
Y
Sharp
P A
PA
Blencowe
B J
BJ
D000818:Animals; D000941:Antigens / Q000378:metabolism; D034961:Antigens, Nuclear; D002467:Cell Nucleus / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D005091:Exons; D006367:HeLa Cells; D006801:Humans; D019476:Insect Proteins / Q000235:genetics; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins / Q000378:metabolism*; D012322:RNA Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012326:RNA Splicing; D016601:RNA-Binding Proteins / Q000378:metabolism*; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000235:genetics / Q000378:metabolism; D017413:Ribonucleoprotein, U2 Small Nuclear / Q000235:genetics / Q000378:metabolism
D000941:Antigens; D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; C070369:DSX protein, Drosophila; D029721:Drosophila Proteins; D019476:Insect Proteins; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear; D017413:Ribonucleoprotein, U2 Small Nuclear; C111710:SRRM1 protein, human