UCSF

As mRNA translation is an energetically costly and crucial operation, cells have developed a plethora of mechanisms to regulate protein production at the post-transcriptional level, controlling initiation and elongation as well as mRNA stability to finely tune translation. In yeast, the DEAD-box protein Dhh1 has been implicated in coordinating translational repression and mRNA decay as a sensor of codon optimality but the exact molecular mechanism and whether this is recapitulated in mammalian cells through the homologue DDX6 still remain unclear. We are developing a chemical genetic inhibition strategy to elucidate the functions of DDX6 as well as other DEAD-box proteins using small molecules that covalently bind an engineered cysteine in the enzyme active site. This approach provides improved temporal and dosing control compared to traditional genetic methods. The latest efforts on this project aim to improve upon the first generation of probes, to discover new small molecule scaffolds, and to develop tools to monitor the probe’s efficacy in cells.Dysregulated protein synthesis is also a hallmark of many diseases, including cancer. The natural product Rocaglamide A (RocA) targets the DEAD-box protein eIF4A to selectively inhibit translation initiation on mRNAs with long, structured 5’-UTRs, including many oncogenes. We hypothesize that dimerizing RocA to add a layer of cell specificity through cellular uptake by IFITM proteins could “tune” the effects of such a potent molecule and broaden its therapeutic index by decreasing on target, off tumor side effects.