Antagonistic effects of T-Ag and VP16 reveal a role for RNA pol II elongation on alternative splicing

Here we investigate the promoter control of alternative splicing by studying two transcriptional activators on templates under replicating conditions. SV40 large T-antigen (T-Ag) activates template replication only 2-fold but transcription 25-fold. T-Ag-mediated replication, reported to inhibit RNA...

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Autores principales: Kadener, S., Cramer, P., Nogués, G., Cazalla, D., De La Mata, M., Fededa, J.P., Werbajh, S.E., Srebrow, A., Kornblihtt, A.R.
Formato: JOUR
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Acceso en línea:http://hdl.handle.net/20.500.12110/paper_02614189_v20_n20_p5759_Kadener
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Sumario:Here we investigate the promoter control of alternative splicing by studying two transcriptional activators on templates under replicating conditions. SV40 large T-antigen (T-Ag) activates template replication only 2-fold but transcription 25-fold. T-Ag-mediated replication, reported to inhibit RNA polymerase II elongation, provokes a 10- to 30-fold increase in the inclusion of the fibronectin EDI exon into mature mRNA. The T-Ag effect is exon specific, occurs in cis and depends strictly on DNA replication and not on cell transformation. VP16, an activator of transcriptional initiation and elongation, has a similar effect on transcription but the opposite effect on splicing: EDI inclusion is inhibited by 35-fold. VP16 completely reverts the T-Ag effect, but a VP16 mutant with reduced elongation ability provokes only partial reversion. Both T-Ag and VP16 promote conspicuous co-localization of mRNA with nuclear speckles that contain the SR protein SF2/ASF, a positive regulator of EDI inclusion. Therefore, we conclude that co-localization of transcripts and speckles is not sufficient to stimulate EDI inclusion.