PI: David Bedwell, PhD / Kim Keeling, PhD
Institution: University of Alabama at Birmingham
Award Period: 2011-2012
Award Total: $165,000
Award Period: 2012-2013
Award Total $165,000
The goal of this project is to identify new compounds with the potential of being developed into a clinical treatment for MPS I patients that harbor an in-frame premature termination codon (PTC; also known as a nonsense mutation). A PTC reduces gene expression through two mechanisms: 1) a PTC terminates translation before a full-length protein can be made; 2) a PTC triggers nonsense-mediated mRNA decay (NMD), a pathway the degrades mRNAs containing a PTC and reduces the amount of mRNA available for translation.
We have screened 1,600 FDA-approved drugs as well as a library of 770,000 small molecules using luciferase-based reporters to identify compounds that either: 1) suppress termination at PTCs; 2) inhibit NMD; or 3) simultaneously suppress termination and inhibit NMD. A total of 165 hits were identified from these two screens and are currently being tested for the ability to restore a-L-iduronidase activity in immortalized mouse embryonic fibroblasts (MEFs) derived from homozygous Idua-W402X mice. We found that among the 66 compounds screened thus far, 12 of the compounds produce a ³ 2-fold increase in a-L-iduronidase activity compared to the vehicle alone control. One FDA-approved compound generates up to a 10-fold increase in a-L-iduronidase activity in MEFs. Our preliminary data suggests that this hit restores a-L-iduronidase by both suppressing the W402X mutation and by inhibiting NMD of the Idua-W402X mRNA. We are currently testing this hit for the ability to attenuate the MPS I phenotype in our Idua-W402X mouse model. We are optimistic that this study will lead to the identification of compounds that can eventually be developed into a treatment for MPS I.