Development of Yeast Model to Study Fragility of the G4C2 Repeat Associated with Amyotrophic Lateral Sclerosis
Repetitive DNA sequences have a tendency to expand, contract, and break. Some short tandem repeat expansions are known to cause neurodegenerative diseases. For example, an expanded CAG repeat is the cause of Huntington’s disease, mytonic dystrophy, and several spinocerebellar ataxias. More recently, the G4C2 repeat in the C9orf72 gene has been implicated as a cause of Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD). The Freudenreich lab has developed a genetic assay that utilizes a yeast artificial chromosome (YAC) that contains an expanded repeat on its right arm that can be used as a reporter of DNA breaks at the repeat. The goal of my project is to modify this system to study the mechanisms of instability and fragility at the G4C2 repeat in the genetically tractable yeast model system. To accomplish this goal, I have incorporated the G4C2 repeat into the YAC. I am now in the position to use this system to identify factors and pathways that influence G4C2 fragility and instability. Because the length of the repeat can determine disease onset and progression, identification of the pathways that influence instability of this repeat will provide key information of potential use in diagnosis and design of therapeutics.