title: Heterogeneous nuclear ribonucleoprotein K represses the production of pro-apoptotic Bcl-xS splice isoform.
abstract: The Bcl-x pre-mRNA is alternatively spliced to produce the anti-apoptotic Bcl-x(L) and the pro-apoptotic Bcl-x(S) isoforms. By performing deletion mutagenesis on a human Bcl-x minigene, we have identified a novel exonic element that controls the use of the 5' splice site of Bcl-x(S). The proximal portion of this element acts as a repressor and is located downstream of an enhancer. Further mutational analysis provided a detailed topological map of the regulatory activities revealing a sharp transition between enhancer and repressor sequences. Portions of the enhancer can function when transplanted in another alternative splicing unit. Chromatography and immunoprecipitation assays indicate that the silencer element interacts with heterogeneous ribonucleoprotein particle (hnRNP) K, consistent with the presence of putative high affinity sites for this protein. Finally, down-regulation of hnRNP K by RNA interference enhanced splicing to Bcl-x(S), an effect seen only when the sequences bound by hnRNP K are present. Our results therefore document a clear role for hnRNP K in preventing the production of the pro-apoptotic Bcl-x(S) splice isoform.
authors.affiliation: RNA/RNP Group, Département de Microbiologie et d'Infectiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada.
authors.forename: Timothée
authors.initials: T
authors.lastname: Revil
authors.forename: Jordan
authors.initials: J
authors.lastname: Pelletier
authors.forename: Johanne
authors.initials: J
authors.lastname: Toutant
authors.forename: Alexandre
authors.initials: A
authors.lastname: Cloutier
authors.forename: Benoit
authors.initials: B
authors.lastname: Chabot
mesh_terms: D017398:Alternative Splicing; D017209:Apoptosis; D002845:Chromatography / Q000379:methods; D004252:DNA Mutational Analysis; D015536:Down-Regulation; D020868:Gene Silencing; D006367:HeLa Cells; D034641:Heterogeneous-Nuclear Ribonucleoprotein K / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D008954:Models, Biological; D020033:Protein Isoforms; D014158:Transcription, Genetic; D051020:bcl-X Protein / Q000096:biosynthesis* / Q000737:chemistry
chemical_list: D034641:Heterogeneous-Nuclear Ribonucleoprotein K; D020033:Protein Isoforms; D051020:bcl-X Protein