Talk abstracts

Talk on Friday 05:30-05:45pm submitted by Ihab Younis

Chemical Screens Reveal Splicing Disruption by Clinical Drugs and Differential Regulation of Constitutive Introns

Ihab Younis, Michael Berg and Gideon Dreyfuss (Howard Hughes Medical Institute, University of Pennsylvania, School of Medicine)

Abstract:
Bioactive compounds have been invaluable for dissecting the mechanisms, regulation and functions of cellular processes. However, very few such reagents have been described for pre-mRNA splicing. To facilitate their systematic discovery, we developed a rapid-response high throughput cell-based assay that measures pre-mRNA splicing utilizing a quantitative reporter system with advantageous features. The reporter, consisting of a destabilized, intron-containing luciferase expressed from a short-lived mRNA, allows rapid screens (<4 hr) thereby obviating potential toxicity of splicing inhibitors. We describe three inhibitors (out of >23,000 screened), all pharmacologically active: clotrimazole, flunarizine and chlorhexidine. Interestingly, none was a general splicing inhibitor. Rather, each caused distinct splicing changes of numerous genes. We further discovered the target of action of chlorhexidine, and show that it is a selective inhibitor of specific Clks that phosphorylate SR-protein splicing factors. Our findings reveal unexpected activities of clinically used drugs in splicing, and uncover differential regulation of constitutively spliced introns.

Keywords: Splicing, High throughput screening, SR proteins