Ataxin 8 (ATXN8)

ATXN8, which encodes a nearly pure polyglutamine expansion protein in the CAG direction, and ATXN8OS, which, when transcribed, produces a noncoding CUG expansion RNA.

Only ATXN8 was translated into protein, which was predicted to contain an initiating methionine followed by a polyglutamine repeat broken only by 2 arg residues near its C terminus. Western blot analysis of transfected HEK293 cells detected ATXN8 at an apparent molecular mass of 40 kD, with variations in size dependent upon the length of the polyglutamine repeat. Immunohistochemical analysis showed that ATXN8 accumulated in nuclear inclusions in Purkinje, medullary, and dentate neurons from human SCA8 autopsy tissue, but not in normal control tissue. ATXN8 intranuclear inclusions were also detected in Purkinje cells and other neurons of SCA8 BAC expansion mice.