The first 171 amino acids of human huntingtin with an expanded glutamine tract of 82 glutamines fused at the N-terminus to the nuclear localization signal sequence from atrophin-1 (first 30 amino acids) is under the control of the mouse prion protein promoter. Western blot and immunohistochemical analyses confirmed that the huntingtin fragments accumulate in nuclear, but not cytoplasmic, compartments.