009 Recapitulation of the hairless mouse phenotype using catalytic oligonucleotides.

Peter B. Cserhalmi-Friedman, Andrei A. Panteleyev, and Angela M. Christiano. Departments of Dermatology and Genetics & Development, Columbia University New York, NY

Ribozyme technology is widely used to target mRNA in a sequence specific fashion, and thus change the expression pattern of cells or tissues. While the goal of mRNA targeting is usually the cleavage of mutant mRNA with the prospect of gene therapy for inherited diseases, in certain instances targeting of wild-type genes can be used therapeutically. Lack of expression of the mouse hairless gene due to inherited mutations leads to the complete loss of hair, known as atrichia. We designed this study to recapitulate the hairless phenotype in a restricted manner by topical application of deoxy-ribozyme targeting molecules to specifically cleave the mouse hairless mRNA. The targeting oligonucleotides were designed using previously reported catalytic core structure and the mRNA sequence of the mouse hairless gene. The targeting molecules were delivered on the back of C57Bl/6J mice using a commercially available liposome reagent. The delivery began immediately after birth, and was repeated daily until day 16. Patches of hair loss were grossly visible on treated areas of dorsal back. Samples for pathology were taken at days 22 and 35, processed and stained using standard techniques. The pathology samples of the treated area from day 22 demonstrated a decreased number of hair follicles, involution of the remaining follicles and separation of the dermal papillae, all characteristic of the hairless phenotype. In contrast, the pathology samples from the non-treated area of the same animal did not show these alterations. The pathology samples of the treated area from day 35 demonstrated the presence of large dermal cysts characteristic of the hairless phenotype, but not normally present in the skin of C57Bl/6J mice. In this study, we successfully recapitulated the hairless phenotype using topically applied target specific catalytic oligonucleotides designed to cleave the mouse hairless mRNA. Our results demonstrate the feasibility of using ribozyme technology to alter gene expression in the skin via topical application, and provide proof of principle for the development of this strategy for permanent hair removal.