Huntington's disease (HD) is a variable onset neurodegenerative disorder caused by the expansion of a CAG repeat sequence in the first exon of the HTT gene. The repeat is polymorphic, especially in the striatum and cortex;and encodes a polyglutamine tract that is the pathological basis for neuronal toxicity and death. There is currently no cure for this devastating disorder. CAG repeat length in this dominant disorder principally determines the onset and severity of HD starting with repetitions that exceed 35-39 CAG repeats. Reducing neuronal toxicity and death by directly targeting the CAG repeat tract would be expected to reduce the severity or at least delay the onset of HD and other triplet repeat disorders. The proposed studies focus directly on the expanded CAG repeat tract as the target of therapy and seek to permanently disrupt or shrink the expanded CAG repeat at the genomic level. To achieve this goal, zinc finger nucleases (ZFNs) will be used to direct DSBs specifically to the expanded HTT repeat allele, with the intent of either shrinking the repeat to benign lengths or eliminating its expression through the induction of frame-shifting indels. In the first aim, this ZFN- based therapy will be tested in primary cells derived from a Huntington's patient. Next-generation sequencing will be used to determine the full spectrum of ZFN-induced changes to the HTT repeat. In conclusion, the proposed research will test key aspects of a ZFN-mediated treatment strategy for shrinking or disrupting expanded CAG repeat alleles that induce neurodegeneration and lead to Huntington's disease and other neurological disorders.

Public Health Relevance

Expanded CAG/CTG repeat tracts are the genetic basis for more than a dozen inherited neurological disorders including Huntington's disease, myotonic dystrophy, and several spinocerebellar ataxias. Despite the multitude of pathologies underlying these disorders, they all share common etiology: the expansion of CAG/CTG repeats from short, benign tracts of about 30 repeats to longer, pathogenic lengths that can extend for several hundred repeats. We will validate a novel therapeutic strategy that targets this common feature-expanded repeats-in human patient cells and in animal models for Huntington's disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21NS079926-02
Application #
8471807
Study Section
Cellular and Molecular Biology of Neurodegeneration Study Section (CMND)
Program Officer
Sutherland, Margaret L
Project Start
2012-07-01
Project End
2014-06-30
Budget Start
2013-07-01
Budget End
2014-06-30
Support Year
2
Fiscal Year
2013
Total Cost
$223,797
Indirect Cost
$79,047
Name
Virginia Polytechnic Institute and State University
Department
None
Type
Organized Research Units
DUNS #
003137015
City
Blacksburg
State
VA
Country
United States
Zip Code
24061
Highnam, Gareth; Franck, Christopher; Martin, Andy et al. (2013) Accurate human microsatellite genotypes from high-throughput resequencing data using informed error profiles. Nucleic Acids Res 41:e32