Adeno-Associated Viral Vector Serotype DJ-Mediated Overexpression of N171-82Q-Mutant Huntingtin in the Striatum of Juvenile Mice Is a New Model for Huntington’s Disease

Abstract

Huntington’s disease (HD) is an autosomal-dominant inherited neurodegenerative disorder characterized by motor, psychiatric and cognitive symptoms. HD is caused by an expansion of CAG repeats in the huntingtin (HTT) gene in various areas of the brain including striatum. There are few suitable animal models to study the pathogenesis of HD and validate therapeutic strategies. Recombinant adeno-associated viral (AAV) vectors successfully transfer foreign genes to the brain of adult mammalians. In this article, we report a novel mouse model of HD generated by bilateral intrastriatal injection of AAV vector serotype DJ (AAV-DJ) containing N171-82Q mutant HTT (82Q) and N171-18Q wild type HTT (18Q; sham). The AAV-DJ-82Q model displayed motor dysfunctions in pole and rotarod tests beginning 4 weeks after viral infection in juvenile mice (8 weeks after birth). They showed behaviors reflecting neurodegeneration. They also showed increased apoptosis, robust glial activation and upregulated representative inflammatory cytokines (tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6), mediators (cyclooxygenase-2 and inducible nitric oxide synthase) and signaling pathways (nuclear factor kappa B and signal transducer and activator of transcription 3 (STAT3)) in the striatum at 10 weeks after viral infection (14 weeks after birth) via successful transfection of mutant HTT into neurons, microglia, and astrocytes in the striatum. However, little evidence of any of these events was found in mice infected with the AAV-DJ-18Q expressing construct. Intrastriatal injection of AAV-DJ-82Q might be useful as a novel in vivo model to investigate the biology of truncated N-terminal fragment (N171) in the striatum and to explore the efficacy of therapeutic strategies for HD.

An Optimization of AAV-82Q-Delivered Rat Model of Huntington’s Disease

“…Our histology re-sults also showed microglia and astrocyte activation in AAV2-82Q-injected rats. This result is similar to the in vivo mouse HD model obtained by stereotaxic infection of AAV-DJ containing N171-82Q, which showed that the viral vector infects neurons, microglia, and astrocytes, but not oligodendrocytes 12) . Based on these results, we confirm the possibility of a new Huntington rat model produced by direct infection of AAV2-82Q into the striatum.…”

“…Additionally, this virus has been inserted into both differentiated and undifferentiated cells and exists as an episomal vector, which allows long-term gene expression [ 5 , 18 ]. Jang et al [ 12 ] have been generated an HD mice model using AAV-DJ-N171-82Q mHTT. AAV-DJ and AAV2 have very strong tropism for neurons and fast expression.…”

“…We aimed to test whether infection of two doses [2×10 12 genome copies (GC)/mL (×1, low dose) or 2×10 13 GC/mL (×10, high dose)] of a customized AAV2 vector with 82 polyglutamines (AAV2-82Q) into the rat striatum altered optimal Huntington behavior and HTT protein expression. Therefore, we investigated changes in behavioral, neuropathological characteristics following direct infection of AAV2-82Q into the caudate putamen of the dorsal striatum in the rat brain to develop a more stable and useful animal model and to overcome the shortcomings of previous animal models.…”

“…AAV has some advantages, including the induction of a weak host immune response, a lack of toxicity in humans, and long-term stability after insertion into host cells compared to lentiviral vectors [ 5 , 18 ]. Previous studies reported the use of AAV for the delivery of 82Q [ 12 ], 97Q [ 29 ], or 138Q [ 3 ] into the mouse or rat striatum to generate an HD model; however, these reports only focused on the neuropathological characteristics of HD. To the best of our knowledge, no optimum genetic rat Huntington model using an adeno-associated virus (AAV-2) vector has been reported to date…”

Intra-striatal AAV2.retro administration leads to extensive retrograde transport in the rhesus macaque brain: implications for disease modeling and therapeutic development

“…chemogenetics 20 ). AAVs have also been used to create animal models of CNS disorders by delivering pathogenic constructs to brain regions of interest, such as the overexpression of a-synuclein in the striatum that results in progressive neurodegeneration and motor phenotypes characteristic of Parkinson's disease [21][22][23] , or of expanded glutamine-encoding CAG repeats to create a striatal degeneration model of Huntington's disease (HD) 21,24,25 , or of amyloid beta to reproduce features of Alzheimer's disease 26,27 .…”