Polyglutamine toxicity induces rod photoreceptor division, morphological transformation or death in Spinocerebellar ataxia 7 mouse retina

In neurodegenerative disorders caused by polyglutamine (polyQ) expansion, polyQ toxicity is thought to trigger a linear cascade of successive degenerative events leading to neuronal death. To understand how neurons cope with polyQ toxicity, we studied a Spinocerebellar ataxia 7 (SCA7) mouse which expresses polyQ-expanded ATXN7 only in rod photoreceptors. We show that in response to polyQ toxicity, SCA7 rods go through a range of radically different cell fates, including apoptotic and non-apoptotic cell death, cell migration, morphological transformation into a round cell or, most remarkably, cell division. The temporal profile of retinal remodeling indicates that some degenerative pathways …