Vulnerability of Purkinje cells induced from spinocerebellar ataxia type 6 patient-derived iPS cells [1]

Spinocerebellar ataxia type 6 (SCA6) is a dominantly inherited neurodegenerative disease characterized by loss of Purkinje cells in the cerebellum. SCA6 is caused by CAG trinucleotide repeat expansion in CACNA1A, which encodes Cav2.1, α1A subunit of P/Q-type calcium channel. However, the pathogenic mechanism and effective therapeutic treatments are still unknown. Here we have succeeded in generation of differentiated Purkinje cells that carry the patient genes by combining disease-specific iPS cells and self-organizing culture technologies. SCA6-iPS cells derived Purkinje cells exhibited increased level of whole Cav2.1 protein while decreased level of its C-terminal fragment and downregulation of the transcriptional targets TAF1 and BTG1. We further demonstrate that SCA6-Purkinje cells exhibit thyroid hormone depletion-dependent degeneration, which can be suppressed by two compounds, thyroid releasing hormone and Riluzole. Thus we have constructed an in vitro disease model recapitulating both ontogenesis and pathogenesis. This model would be useful for pathogenic investigation and drug screening. Examination of mRNA profile in 1 ES cell line, two healthy donnor-derived iPS cell lines, three case-derived iPS cell lines and 1 normal dermal fibroblasts.