ATAXIN-1 interacts with the repressor Capicua in its native complex to cause SCA1 neuropathology.

Lam YC, Bowman AB, Jafar-Nejad P, Lim J, Richman R, Fryer JD, Hyun ED, Duvick LA, Orr HT, Botas J, Zoghbi HY
Cell. 2006 127 (7): 1335-47

PMID: 17190598 · DOI:10.1016/j.cell.2006.11.038

Spinocerebellar ataxia type 1 (SCA1) is one of several neurodegenerative diseases caused by expansion of a polyglutamine tract in the disease protein, in this case, ATAXIN-1 (ATXN1). A key question in the field is whether neurotoxicity is mediated by aberrant, novel interactions with the expanded protein or whether its wild-type functions are augmented to a deleterious degree. We examined soluble protein complexes from mouse cerebellum and found that the majority of wild-type and expanded ATXN1 assembles into large stable complexes containing the transcriptional repressor Capicua. ATXN1 directly binds Capicua and modulates Capicua repressor activity in Drosophila and mammalian cells, and its loss decreases the steady-state level of Capicua. Interestingly, the S776A mutation, which abrogates the neurotoxicity of expanded ATXN1, substantially reduces the association of mutant ATXN1 with Capicua in vivo. These data provide insight into the function of ATXN1 and suggest that SCA1 neuropathology depends on native, not novel, protein interactions.

MeSH Terms (22)

Amino Acid Sequence Animals Animals, Genetically Modified Ataxin-1 Ataxins Brain Cerebellum Conserved Sequence Drosophila Eye Abnormalities Humans Mice Molecular Sequence Data Mutation Nerve Tissue Proteins Nuclear Proteins Peptides Repressor Proteins Sequence Homology, Amino Acid Spinocerebellar Ataxias Transcription, Genetic Wings, Animal

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