Gene profiling links SCA1 pathophysiology to glutamate signaling in Purkinje cells of transgenic mice

Spinocerebellar ataxia type 1 (SCA1) is a neurodegenerative disease caused by the expansion of a polyglutamine repeat within the disease protein, ataxin 1. To elucidate cellular pathways involved in SCA1, we used DNA microarrays to determine the pattern of gene expression in SCA1 transgenic mice at two specific times in the disease process; 5 weeks, a timepoint prior to onset of pathology, and 12 weeks, at the midpoint of the disease progression. Taking advantage of the availability of three SCA1 transgenic mouse lines, each expressing a different form of ataxin-1, we utilized a strategy that resulted in the identification of a limited number of genes with an altered pattern of expression specific to the development of disease. By comparing the pattern of gene expression in the SCA1 ataxic B05-ataxin-1[82Q] transgenic mouse line with those seen in two non-ataxic lines, A02-ataxin-1[30Q] and K772T-[82Q], nine genes were identified whose expression was consistently altered in the cerebellum of B05[82Q] mice at 5 and 12 weeks of age. Interestingly, five of the genes in this group form a biological cohort centered on glutamate signaling pathways in Purkinje cells.