An antisense CAG repeat transcript at JPH3 locus mediates expanded polyglutamine protein toxicity in Huntington's disease-like 2 mice.
Huntington's disease-like-2 (HDL2) is a phenocopy of Huntington's disease caused by CTG/CAG repeat expansion at the Junctophilin-3 (JPH3) locus. The mechanisms underlying HDL2 pathogenesis remain unclear. Here we developed a BAC transgenic mouse model of HDL2 (BAC-HDL2) that exhibits progressive motor deficits, selective neurodegenerative pathology, and ubiquitin-positive nuclear inclusions (NIs). Molecular analyses reveal a promoter at the transgene locus driving the expression of a CAG repeat transcript (HDL2-CAG) from the strand antisense to JPH3, which encodes an expanded polyglutamine (polyQ) protein. Importantly, BAC-HDL2 mice, but not control BAC mice, accumulate polyQ-containing NIs in a pattern strikingly similar to those in the patients. Furthermore, BAC mice with genetic silencing of the expanded CUG transcript still express HDL2-CAG transcript and manifest polyQ pathogenesis. Finally, studies of HDL2 mice and patients revealed CBP sequestration into NIs and evidence for interference of CBP-mediated transcriptional activation. These results suggest overlapping polyQ-mediated pathogenic mechanisms in HD and HDL2.
Pubmed ID: 21555070 RIS Download
Age Factors | Analysis of Variance | Animals | Cells, Cultured | Cerebral Cortex | Chromatin Immunoprecipitation | Disease Models, Animal | Embryo, Mammalian | Gene Expression Regulation | Humans | Huntington Disease | Intranuclear Inclusion Bodies | Membrane Proteins | Mice | Mice, Transgenic | Motor Activity | Neurons | Oligodeoxyribonucleotides, Antisense | Organ Size | Peptides | Time Factors | Transfection | Trinucleotide Repeat Expansion | Ubiquitin