Background We have previously shown that constitutive heterozygosity for Hdac4 results in a delay in the formation of HTT aggregates in the cytoplasm, rescues electrophysiological defects, improves rotarod impairment and delays end stage disease. However, the beneficial consequences of decreasing Hdac4 levels after weaning, thereby more closely mimicking a potential pharmacological trial, are unknown.
Aims To test the effect of a temporal reduction in Hdac4 levels in R6/2 mice.
Methods The tolerability of tamoxifen dosing regimens in wild type and R6/2 mice was investigated at 4, 6 and 8 weeks of age. Mice expressing a tamoxifen inducible ubiquitously expressed Cre transgene (pCAG-CAGGCre-ERTM) were crossed to mice that are heterozygous for a conditional Hdac4 knock-out allele (Hdac4 flox) and the extent of recombination across the floxed Hdac4 allele was established using PCR and qPCR assays. The triple cross between pCAG-CAGGCre-ERTM, Hdac4 flox and R6/2 was set up and the effect of Hdac4 reduction on aggregation levels at 4 weeks of age was measured using the Seprion ligand ELISA.
Results Tamoxifen administration at 85 mg/kg was tolerated by R6/2 and wild type mice aged 4 and 6 weeks of age and this led to recombination across the floxed Hdac4 gene in the five brain regions examined. The triple cross between pCAG-CAGGCre-ERTM, Hdac4 flox and R6/2 has been performed and the tissues are in the process of being analysed.
Conclusions The results of this study will be presented.
Funding CHDI Foundation