title: Novel splicing factor RBM25 modulates Bcl-x pre-mRNA 5' splice site selection.
abstract: RBM25 has been shown to associate with splicing cofactors SRm160/300 and assembled splicing complexes, but little is known about its splicing regulation. Here, we characterize the functional role of RBM25 in alternative pre-mRNA splicing. Increased RBM25 expression correlated with increased apoptosis and specifically affected the expression of Bcl-x isoforms. RBM25 stimulated proapoptotic Bcl-x(S) 5' splice site (5' ss) selection in a dose-dependent manner, whereas its depletion caused the accumulation of antiapoptotic Bcl-x(L). Furthermore, RBM25 specifically bound to Bcl-x RNA through a CGGGCA sequence located within exon 2. Mutation in this element abolished the ability of RBM25 to enhance Bcl-x(S) 5' ss selection, leading to decreased Bcl-x(S) isoform expression. Binding of RBM25 was shown to promote the recruitment of the U1 small nuclear ribonucleoprotein particle (snRNP) to the weak 5' ss; however, it was not required when a strong consensus 5' ss was present. In support of a role for RBM25 in modulating the selection of a 5' ss, we demonstrated that RBM25 associated selectively with the human homolog of yeast U1 snRNP-associated factor hLuc7A. These data suggest a novel mode for Bcl-x(S) 5' ss activation in which binding of RBM25 with exonic element CGGGCA may stabilize the pre-mRNA-U1 snRNP through interactions with hLuc7A.
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA.
authors.forename: Anyu
authors.initials: A
authors.lastname: Zhou
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Ou
authors.forename: Aeri
authors.initials: A
authors.lastname: Cho
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Benz
authors.forename: Shu-Ching
authors.initials: SC
authors.lastname: Huang
mesh_terms: D017398:Alternative Splicing; D017209:Apoptosis; D002460:Cell Line; D005091:Exons; D006801:Humans; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics; D017434:Protein Structure, Tertiary; D022821:RNA Splice Sites; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D051020:bcl-X Protein / Q000235:genetics*
chemical_list: C404083:LUC7L3 protein, human; D009687:Nuclear Proteins; D020033:Protein Isoforms; D022821:RNA Splice Sites; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D051020:bcl-X Protein