The Ubiquitin Proteasome System and Cerebellar Developmental Disease

A variety of developmental diseases of the cerebellum are associated with dysregulation of proteins regulated by the ubiquitin proteasome system (UPS). Dysfunction of the UPS is observed in several types of spinocerebellar ataxias associated with polyglutamine accumulation. Spinocerebellar ataxia type 3 is caused by a genetic defect ion the Atxn3 gene, which codes for a deubiquitinase enzyme. Defects in expression of a variety of ubiquitin ligases are associated with Friedreich’s ataxia, ataxia-telangiectasia, and cerebellar hemangioblastoma. Mutations in a number of genes for ubiquitin ligases are risk factors for autism. Subtypes of medulloblastoma are associated with specific defects in proteasome subunits and with deficiencies in components of the APC/C ubiquitin ligase complex regulating the cell cycle. Targeting various components of the UPS system may contribute to a future therapeutic approach which restores protein homeostasis in various cerebellar diseases.