Control of alternative splicing through siRNA-mediated transcriptional gene silencing

ALLÓ M; BUGGIANO V; FEDEDA JP; PETRILLO E; SCHOR IE; DE LA MATA M; AGIRRE E; PLASS M; EYRAS E; ELELA SA; KLINCK R; CHABOT B; KORNBLIHTT AR

Nature Structural and Molecular Biology

Nature Publishing Group

Año: 2009 vol. 16 p. 717 - 724

1545-9993

<!-- /* Font Definitions */ @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:0; mso-generic-font-family:roman; mso-font-pitch:variable; mso-font-signature:-1610611985 1107304683 0 0 159 0;} @font-face {font-family:Palatino; mso-font-alt:"Book Antiqua"; mso-font-charset:0; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:50331648 0 0 0 1 0;} @font-face {font-family:Times; panose-1:2 2 6 3 5 4 5 2 3 4; mso-font-charset:0; mso-generic-font-family:roman; mso-font-pitch:variable; mso-font-signature:-536859921 -1073711039 9 0 511 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-unhide:no; mso-style-qformat:yes; mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; mso-bidi-font-size:10.0pt; font-family:Palatino; mso-fareast-font-family:Times; mso-hansi-font-family:Palatino; mso-bidi-font-family:"Times New Roman"; mso-ansi-language:EN-US; mso-fareast-language:ES-TRAD;} .MsoChpDefault {mso-style-type:export-only; mso-default-props:yes; font-size:10.0pt; mso-ansi-font-size:10.0pt; mso-bidi-font-size:10.0pt;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Small interfering RNAs (siRNAs) mediate post-transcriptional gene silencing (PTGS) by promoting mRNA degradation. When targeting promoter regions, siRNAs participate in a previously proposed alternative pathway known as transcriptional gene silencing (TGS) by promoting heterochromatin formation and transcriptional inhibition. Here we show that siRNAs targeting intronic or exonic sequences located close to a fibronectin (FN) alternative exon regulate its alternative pre-mRNA splicing. The effect is observed in hepatoma and HeLa cells when the antisense strands of intronic siRNAs are engineered to enter the silencing pathway, suggesting the need for hybridization with nascent pre-mRNA. Surprisingly, in HeLa cells the sense strand is also effective, which is consistent with identification of an antisense FN transcript in this cell type that may act as target. The effect is AGO1-dependent and is counterbalanced by factors that favor chromatin opening or transcriptional elongation. The promotion of heterochromatin marks (H3K9me2 and H3K27me3) at the target site, the need for HP1a, and an observed local reduction in Pol II processivity suggest a mechanism involving the kinetic coupling of transcription and alternative splicing.