Capicua Homolog (CIC)

The human cDNA predicted a 1,608-amino acid protein. Human and mouse genes exhibit 92% identity, with 100% identity in the HMG domain. Because the level of similarity of CIC to other SOX genes is insufficient for inclusion as a genuine member of the SOX subfamily, CIC represents a new member of a SOX-related HMG subfamily. RT-PCR of developing mouse central nervous system showed that Cic is highly expressed in the developing mouse brain, particularly in the immature granular cells in the cerebellum, hippocampus, and olfactory bulb.Atxn1 directly bound Cic and modulated Cic repressor activity in Drosophila and mammalian cells, and its loss decreased the steady state level of Cic. Interestingly, the S776A mutation, which abrogates the neurotoxicity of expanded Atxn1, substantially reduced the association of mutant Atxn1 with Cic in vivo.