An Antisense CAG Repeat Transcript at JPH3 Locus Mediates Expanded Polyglutamine Protein Toxicity in Huntington's Disease-like 2 Mice

• DOI: 10.1016/j.neuron.2011.03.021
• Publication Date: 2011-05-21T01:02:37Z
• Authors: Brian Wilburn; Dobrila D. Rudnicki; Jing Zhao; Tara Murphy Weitz; Yin Cheng; Xiaofeng Gu; Erin Greiner; Chang Sin Park; Nan Wang; Bryce L. Sopher; Albert R. La Spada; Alex Osmand; Russell L. Margolis; Yi E. Sun; X. William Yang
• Keywords: Phenocopy; Pathogenesis

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.