Early onset (DYT1) dystonia is a hereditary movement disorder involving severe motor impairment believed to reflect a dysfunction within the basal ganglia. Affected individuals develop sustained, involuntary muscle contractions and twisted postures for which few treatment options exist. Most cases are linked to a heterozygous codon deletion which removes a glutamic acid from the carboxy terminus of the encoded protein, torsinA. TorsinA is thought to function within the endoplasmic reticulum (ER) as a molecular chaperone within the secretory pathway. Multiple studies suggest that DYT1 pathogenesis reflects a loss of torsinA function, possibly due to dominant negative effects of the mutant protein. We recently performed a target-based screen that identified a set of small molecule ligands for torsinA, one of which rescues a functional defect in DYT1 cells. This compound is a novel aldehyde synthesized by an academic laboratory and not yet FDA-approved. In this project we propose to use this compound as a probe to find other, known FDA-approved drugs which mimic its effects. If such drugs exist, they could potentially be moved into human trials for dystonia more quickly as they are already approved for clinical use. We will first perform a genomewide expression analysis on primary fibroblasts from DYT1 patients and control in the presence or absence of our lead compound. These gene signatures will be used to query a new database, the Connectivity Map (CMap). CMap was created by obtaining gene expression signatures from cultured cells treated individually with a large collection of known drugs. The database software will allow us to seek drugs predicted to phenocopy our test compound and/or reverse the gene expression profile in untreated DYT1 cells. We will further analyze the gene expression results using Gene Set Enrichment Analysis (GSEA) to identify functional pathways that may be differentially regulated in DYT1 cells relative to controls. We will obtain any drugs identified by CMap as well as ones known to act on targets and/or pathways implicated by the GSEA analysis and compare the new candidates to our test compound in a DYT1 cellular assay. To our knowledge, this analysis would be the first transcriptional profile of human DYT1 cells ever performed and would take advantage of the large inventory of primary dystonia patient cells collected by our team. The results may offer new insight into DYT1 pathogenesis by revealing cellular pathways perturbed by the mutant protein while also seeking new candidates to treat dystonia.
Early onset (DYT1) dystonia is a crippling movement disorder that typically begins during adolescence. Although current therapeutic options are limited, the normal brain structure and absence of cell death observed in affected individuals suggest that the disease could be drug treatable. In this project we propose a novel strategy to find new drug candidates for dystonia that combines (1) genomewide expression profiling of primary DYT1 patient vs. control cells;and (2) a powerful new discovery tool, the Connectivity Map, that links gene expression signatures to specific known drugs.
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