Sphingolipid Metabolism Governs Purkinje Cell Patterned Degeneration In Atxn1[82q]/+ Mice

August 11, 2020) Patterned degeneration of Purkinje cells (PCs) can be observed in a wide range of neuropathologies, but mechanisms behind nonrandom cerebellar neurodegeneration remain unclear. Sph-ingolipid metabolism dyshomeostasis typically leads to PC neu-rodegeneration; hence, we questioned whether local sphingolipid balance underlies regional sensitivity to pathological insults. Here, we investigated the regional compartmentalization of sphin-golipids and their related enzymes in the cerebellar cortex in healthy and pathological conditions. Analysis in wild-type ani -mals revealed higher sphingosine kinase 1 (Sphk1) levels in the flocculonodular cerebellum, while sphingosine-1-phosphate (S1P) levels were higher in the anterior cerebellum. Next, we investigated a model for spinocerebellar ataxia type 1 (SCA1) driven by the transgenic expression of the expanded Ataxin 1 protein with 82 glutamine (82Q), exhibiting severe PC degenera-tion in the anterior cerebellum while the flocculonodular region is preserved. In Atxn1(82Q]/+ mice, we found that levels of Sphk1 and Sphk2 were region-specific decreased and S1P levels increased, particularly in the anterior cerebellum. To determine if there is a causal link between sphingolipid levels and neu-rodegeneration, we deleted the Sphk1 gene in Atxn1(82Q]/+ mice. Analysis of Atxn1(82Q]/+; Sphk1(-/-) mice confirmed a neuroprotective effect, rescuing a subset of PCs in the ante-rior cerebellum, in domains reminiscent of the modules defined by AldolaseC expression. Finally, we showed that Sphk1 dele-tion acts on the ATXN1[82Q] protein expression and prevents PC degeneration. Taken together, our results demonstrate that there are regional differences in sphingolipid metabolism and that this metabolism is directly involved in PC degeneration in Atxn1(82Q]/+ mice.