Rosa HD

Huntington's disease (HD) is an adult-onset, autosomal-dominant neurodegenerative disease that is clinically characterized by a triad of movement disorders (i.e., chorea and bradykinesia), psychiatric symptoms, and cognitive deficits. In afflicted patients, symptoms usually progress relentlessly until death in 15-20 years after disease onset. HD is one of nine neurodegenerative disorders caused by a CAG repeat expansion encoding a polyglutamine (polyQ) repeat in otherwise unrelated proteins. In HD, the mutated Huntingtin (mhtt) protein is ubiquitously expressed in both neuronal and nonneuronal tissues. The polyQ repeat, located in the N terminus of huntingtin (htt), is normally less than 36, but is expanded to more than 37 in HD patients. In all polyQ disorders, there is an inverse relationship between the length of polyQ and the age of disease onset. Currently, there is no effective treatment or cure for HD or any other polyQ disorder.

Researchers at UCLA have developed a Cre/LoxP conditional mouse model of HD (termed RosaHD mice) in which expression of a toxic mutant huntingtin Exon 1 (mhtt-exon1) fragment, driven by the endogenous ubiquitously-expressing Rosa26 promoter, can be switched on by Cre recombinase.