title: Protein kinase C-dependent control of Bcl-x alternative splicing.
abstract: The alternative splicing of Bcl-x generates the proapoptotic Bcl-x(S) protein and the antiapoptotic isoform Bcl-x(L). Bcl-x splicing is coupled to signal transduction, since ceramide, hormones, and growth factors alter the ratio of the Bcl-x isoforms in different cell lines. Here we report that the protein kinase C (PKC) inhibitor and apoptotic inducer staurosporine switches the production of Bcl-x towards the x(S) mRNA isoform in 293 cells. The increase in Bcl-x(S) elicited by staurosporine likely involves signaling events that affect splicing decisions, because it requires active transcription and no new protein synthesis and is independent of caspase activation. Moreover, the increase in Bcl-x(S) is reproduced with more specific inhibitors of PKC. Alternative splicing of the receptor tyrosine kinase gene Axl is similarly affected by staurosporine in 293 cells. In contrast to the case for 293 cells, PKC inhibitors do not influence the alternative splicing of Bcl-x and Axl in cancer cell lines, suggesting that these cells have sustained alterations that uncouple splicing decisions from PKC-dependent signaling. Using minigenes, we show that an exonic region located upstream of the Bcl-x(S) 5' splice site is important to mediate the staurosporine shift in Bcl-x splicing. When transplanted to other alternative splicing units, portions of this region confer splicing modulation and responsiveness to staurosporine, suggesting the existence of factors that couple splicing decisions with PKC signaling.
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, Canada J1H 5N4.
authors.forename: Timothée
authors.initials: T
authors.lastname: Revil
authors.forename: Johanne
authors.initials: J
authors.lastname: Toutant
authors.forename: Lulzim
authors.initials: L
authors.lastname: Shkreta
authors.forename: Daniel
authors.initials: D
authors.lastname: Garneau
authors.forename: Philippe
authors.initials: P
authors.lastname: Cloutier
authors.forename: Benoit
authors.initials: B
authors.lastname: Chabot
mesh_terms: D017398:Alternative Splicing / Q000187:drug effects / Q000235:genetics*; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D005091:Exons / Q000235:genetics; D006801:Humans; D015513:Oncogene Proteins / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011518:Proto-Oncogene Proteins; D012322:RNA Precursors / Q000235:genetics; D022821:RNA Splice Sites; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D019311:Staurosporine / Q000494:pharmacology; D051020:bcl-X Protein / Q000378:metabolism*; D000094963:Axl Receptor Tyrosine Kinase
chemical_list: D015513:Oncogene Proteins; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D012322:RNA Precursors; D022821:RNA Splice Sites; D051020:bcl-X Protein; D020794:Receptor Protein-Tyrosine Kinases; D011493:Protein Kinase C; D020169:Caspases; D019311:Staurosporine; D000094963:Axl Receptor Tyrosine Kinase; C000722289:AXL protein, human