Reduced fidelity of branch point recognition and alternative splicing induced by the anti-tumor drug spliceostatin A
- 1Centre de Regulació Genòmica, 08003 Barcelona, Spain;
- 2Universitat Pompeu Fabra, 08003 Barcelona, Spain;
- 3Institució Catalana de Recerca i Estudis Avançats (ICREA), 08003 Barcelona, Spain
Abstract
Spliceostatin A (SSA) is a stabilized derivative of a Pseudomonas bacterial fermentation product that displays potent anti-proliferative and anti-tumor activities in cancer cells and animal models. The drug inhibits pre-mRNA splicing in vitro and in vivo and binds SF3b, a protein subcomplex of U2 small nuclear ribonucleoprotein (snRNP), which is essential for recognition of the pre-mRNA branch point. We report that SSA prevents interaction of an SF3b 155-kDa subunit with the pre-mRNA, concomitant with nonproductive recruitment of U2 snRNP to sequences 5′ of the branch point. Differences in base-pairing potential with U2 snRNA in this region lead to different sensitivity of 3′ splice sites to SSA, and to SSA-induced changes in alternative splicing. Indeed, rather than general splicing inhibition, splicing-sensitive microarray analyses reveal specific alternative splicing changes induced by the drug that significantly overlap with those induced by knockdown of SF3b 155. These changes lead to down-regulation of genes important for cell division, including cyclin A2 and Aurora A kinase, thus providing an explanation for the anti-proliferative effects of SSA. Our results reveal a mechanism that prevents nonproductive base-pairing interactions in the spliceosome, and highlight the regulatory and cancer therapeutic potential of perturbing the fidelity of splice site recognition.
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Footnotes
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↵4 Corresponding author.
E-MAIL juan.valcarcel{at}crg.es; FAX 34-93-224-0899.
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Article is online at http://www.genesdev.org/cgi/doi/10.1101/gad.2014311.
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Supplemental material is available for this article.
- Received November 18, 2010.
- Accepted January 10, 2011.
- Copyright © 2011 by Cold Spring Harbor Laboratory Press