Embryonic stem cells expressing expanded CAG repeats undergo aberrant neuronal differentiation and have persistent Oct-4 and REST/NRSF expression.

Nine neurodegenerative disorders are caused by CAG/polyglutamine (polyQ) repeat expansions. The molecular mechanisms responsible for disease-specific neurodegeneration remain elusive. We developed an embryonic stem (ES) cell-based model to probe the role of polyQ tract expansion in neuronal degeneration. ES cells containing expanded CAG repeats in the hypoxanthine phosphoribosyltransferase (Hprt) gene develop features typical of CAG-mediated neuropathology, exhibit length-dependent decrease in survival, undergo aberrant neuronal differentiation as well as persistent Oct-4 and Repressor element-1 transcription factor/neuron restrictive silencer factor (REST/NRSF) expression. This novel model will allow analysis of the molecular pathogenesis of neuronal degeneration and can be used to rapidly screen therapeutic interventions for these fatal diseases.