CHARACTERIZATION OF AN INDUCIBLE TRANSGENIC MOUSE MODEL FOR FRAGILE X-ASSOCIATED TREMOR/ATAXIA SYNDROME (FXTAS)

Abstract

Background: FXTAS (fragile X-associated tremor/ataxia syndrome) is a neurodegenerative disease with tremor and ataxia as the primary symptoms and ubiquitin-positive intranuclear inclusions as the major neuropathological hallmark. FXTAS affects premutation males with an expanded premutation CGG repeat in the promoter of the FMR1 gene. The expanded premutation CGG RNA is considered toxic. Inducible transgenic mice were generated, using the Tet-on system to express transgene expanded premutation 99CGG along with an eGFP reporter under control of dox (doxycycline) induction, as well as specific driver promoter, the GFA2-rtTA and PrP-rtTA. This study aims to characterize those mouse models so they would be ready to be used for further studies. Methods: Immunohistochemistry, Western blot, and RT-Q-PCR techniques were used to characterize the transgene expression of the transgenic mice. Characterization of ubiquitin inclusions formation used immunohistochemistry technique. Results: The Tet-on-99CGG-eGFP transgene worked in vivo, while Tet-on- 11CGG-eGFP lost its expression. Tet-on-99CGG-eGFP/GFA2-rtTA bigenic mice did not work in vivo, while Tet-on-99CGG-eGFP/PrP-rtTA bigenic mice did work. As expected, the Tet-on-99CGG-eGFP/PrP-rtTA mice formed the FXTAS hallmark, the ubiquitin-positive intranuclear inclusions after 12 weeks of dox induction. Conclusions: Mouse model Tet-on-99CGG-eGFP/PrP-rtTA worked well, and were ready to be used for main further studies. Keywords: FXTAS, FMR1 gene, transgenic mice, Tet-on, PrP, GFA2,reversibility, ubiquitin inclusions