title: Prp40 pre-mRNA processing factor 40 homolog B (PRPF40B) associates with SF1 and U2AF65 and modulates alternative pre-mRNA splicing in vivo.
abstract: The first stable complex formed during the assembly of spliceosomes onto pre-mRNA substrates in mammals includes U1 snRNP, which recognizes the 5' splice site, and the splicing factors SF1 and U2AF, which bind the branch point sequence, polypyrimidine tract, and 3' splice site. The 5' and 3' splice site complexes are thought to be joined together by protein-protein interactions mediated by factors that ensure the fidelity of the initial splice site recognition. In this study, we identified and characterized PRPF40B, a putative mammalian ortholog of the U1 snRNP-associated yeast splicing factor Prp40. PRPF40B is highly enriched in speckles with a behavior similar to splicing factors. We demonstrated that PRPF40B interacts directly with SF1 and associates with U2AF(65). Accordingly, PRPF40B colocalizes with these splicing factors in the cell nucleus. Splicing assays with reporter minigenes revealed that PRPF40B modulates alternative splice site selection. In the case of Fas regulation of alternative splicing, weak 5' and 3' splice sites and exonic sequences are required for PRPF40B function. Placing our data in a functional context, we also show that PRPF40B depletion increased Fas/CD95 receptor number and cell apoptosis, which suggests the ability of PRPF40B to alter the alternative splicing of key apoptotic genes to regulate cell survival.
authors.affiliation: Department of Molecular Biology.
authors.forename: Soraya
authors.initials: S
authors.lastname: Becerra
authors.affiliation: Department of Molecular Biology.
authors.forename: Marta
authors.initials: M
authors.lastname: Montes
authors.affiliation: Department of Cell Biology and Immunology, Instituto de Parasitología y Biomedicina "López Neyra" (IPBLN-CSIC), PTS, Granada 18016, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Hernández-Munain
authors.affiliation: Department of Molecular Biology, csune@ipb.csic.es.
authors.forename: Carlos
authors.initials: C
authors.lastname: Suñé
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D017209:Apoptosis / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics*; D002470:Cell Survival / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D005091:Exons / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics*; D011485:Protein Binding; D022821:RNA Splice Sites / Q000235:genetics; D000072260:RNA Splicing Factors; D012261:Ribonucleoproteins / Q000235:genetics*; D017381:Spliceosomes / Q000378:metabolism; D000072668:Splicing Factor U2AF; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C491404:PRPF40A protein, human; C000596821:PRPF40B protein, human; D022821:RNA Splice Sites; D000072260:RNA Splicing Factors; D012261:Ribonucleoproteins; C107467:SF1 protein, human; D000072668:Splicing Factor U2AF; D014157:Transcription Factors; C000607494:U2AF2 protein, human
keywords: PRPF40B; alternative splicing; mRNA processing