DYT6 dystonia is a hereditary movement disorder for which few treatment options exist. Affected individuals develop involuntary muscle contractions, primarily of upper limbs and cranial region with frequent speech defects due to laryngeal dystonia. The causative gene was recently identified as THAP1 which encodes a DNA binding protein, THAP1 (thanatos-associated protein [THAP] domain-containing apoptosis-associated protein- 1). Multiple groups have now independently linked 35 THAP1 mutations to dystonia in genetically diverse populations throughout the world, thereby revealing DYT6 as a substantial cause of familial dystonia. Most mutations impact residues known to be critical for THAP1's DNA binding activity, raising the hypothesis that DYT6 pathogenesis may involve aberrant transcriptional activity due to insufficient levels of functional THAP1 protein. Consistent with that hypothesis, we have detected a transcriptional phenotype in lymphoblasts bearing one of the DYT6 mutations, relative to control cells. In this project we propose to develop and pilot a novel assay for identifying new drug candidates for treating DYT6. The assay uses technology that has been largely applied to drug discovery in cancers similarly linked to aberrant transcription factor activity, such as acute myeloid leukemia (AML) and Ewing sarcoma. Using DNA microarrays, we will first define a gene expression signature distinguishing patient from control cells, using lines representing 18 DYT6 genotypes to find common markers representative of the DYT6 disease state. That signature will then be converted to a low cost assay based on the Luminex FlexMAP" system, which provides an automated method for capturing and quantifying target transcripts from cells in a conventional cell-based assay format. After validating that the Luminex assay recapitulates the microarray signature with sufficient reproducibility and Z'factor, we will pilot the screen in a mixed collection of 15,000 small molecules to seek compounds that normalize the DYT6 transcriptional phenotype. We expect potential outcomes of this project to be: (1) a validated assay that could be used for a large scale screening campaign to find novel DYT6 therapeutics (2) an established signature- based screening platform that could be generalized to other forms of hereditary dystonia;and (3) candidates from the pilot screen to be further characterized in DYT6 model systems.
DYT6 is a disabling form of dystonia involving sustained, involuntary muscle contractions for which few treatment options exist. The causative gene was recently identified as THAP1, which encodes a DNA binding protein, THAP1. Since the initial discovery, THAP1 mutations have ben linked to dystonia in diverse populations more frequently than any other known locus. In this project we propose to develop and pilot a novel assay for finding new drug candidates for DYT6, using a generic, gene expression-based screening technology that in future studies could be generalized to other forms of hereditary dystonia.
|Sengel, Cem; Gavarini, Sophie; Sharma, Nutan et al. (2011) Dimerization of the DYT6 dystonia protein, THAP1, requires residues within the coiled-coil domain. J Neurochem 118:1087-100|
|Bragg, D Cristopher; Armata, Ioanna A; Nery, Flavia C et al. (2011) Molecular pathways in dystonia. Neurobiol Dis 42:136-47|