SEQUENCE LISTING

The present application is being filed along with a Sequence Listing in electronic format. The Sequence Listing is provided as a file entitled BIOL0113USC3SEQ_ST25.txt created May 15, 2017, which is 488 Kb in size. The information in the electronic format of the sequence listing is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

Provided herein are methods, compounds, and compositions for reducing expression of huntingtin mRNA and protein in an animal. Such methods, compounds, and compositions are useful, for example, to treat, prevent, or ameliorate Huntington's disease.

BACKGROUND

Huntington's disease (HD) is a devastating autosomal dominant, neurodegenerative disease caused by a CAG trinucleotide repeat expansion encoding an abnormally long polyglutamine (PolyQ) tract in the huntingtin protein. The Huntington disease gene was first mapped in 1993 (The Huntington's Disease Collaborative Research Group. Cell. 1993, 72:971-83), consisting of a gene, IT15, which contained a polymorphic trinucleotide repeat that is expanded and unstable on HD chromosomes. Although CAG repeats in the normal size range are usually inherited as Mendelian alleles, expanded HD repeats are unstable through meiotic transmission and are found to be expanded beyond the normal size range (6-34 repeat units) in HD patients.

Both normal and variant huntingtin protein are localized chiefly in the cytoplasm of neurons (DiFiglia et al., Neuron 1995, 14:1075-81). As a result of excessive polyglutamine length, huntingtin protein forms aggregates in the cytoplasm and nucleus of CNS neurons (Davies et al., Cell 1997, 90:537-548). Both transgenic animals and genetically modified cell lines have been used to investigate the effects of expanded polyQ repeats on the localization and processing of huntingtin. However, it is still unclear whether the formation of aggregates per se is the essential cytotoxic step or a consequence of cellular dysfunction.

HD is characterized by progressive chorea, psychiatric changes and intellectual decline. This dominant disorder affects males and females equally, and occurs in all races (Gusella and MacDonald, Curr. Opin. Neurobiol. 1995 5:656-62). Symptoms of HD are due to the death of neurons in many brain regions, but is most apparent in the striatum, particularly in the caudate nucleus, which suffers a progressive gradient of cell loss that ultimately decimates the entire structure. Although the gene encoding huntingtin is expressed ubiquitously (Strong, T. V. et al., Nat. Genet. 1995, 5:259-263), selective cell loss and fibrillary astrocytosis is observed in the brain, particularly in the caudate and putamen of the striatum and in the cerebral cortex of HD patients (Vonsattel, J-P. et al., Neuropathol. Exp. Neurol. 1985, 44:559-577), and, to a lesser extent, in the hippocampus (Spargo, E. et al., J. Neurol. Neurosurg. Psychiatry 1993, 56:487-491) and the subthalamus (Byers, R. K. et al., Neurology 1973, 23:561-569).

Huntingtin is crucial for normal development and may be regarded as a cell survival gene (Nasir et al., Human Molecular Genetics, Vol 5, 1431-1435). The normal function of huntingtin remains incompletely characterized, but based upon protein-protein interactions, it appears to be associated with the cytoskeleton and required for neurogenesis (Walling et al., J. Neurosci Res.

1998, 54:301-8). Huntingtin is specifically cleaved during apoptosis by a key cysteine protease, apopain, known to play a pivotal role in apoptotic cell death. The rate of cleavage is enhanced by longer polyglutamine tracts, suggesting that inappropriate apoptosis underlies HD.

Antisense technology is emerging as an effective means for reducing the expression of specific gene products and may therefore prove to be uniquely useful in a number of therapeutic, diagnostic, and research applications for the modulation of huntingtin expression. (See U.S. Patent Publication Nos. 2008/0039418 and 2007/0299027)

Antisense compounds for modulating expression of huntingtin are disclosed in the aforementioned published patent applications. However, there remains a need for additional such compounds.

SUMMARY OF THE INVENTION

Provided herein are methods, compounds, and compositions for modulating expression of huntingtin and treating, preventing, delaying or ameliorating Huntington's disease and/or a symptom thereof.

