An ovine transgenic Huntington's disease model

Abstract

Huntington's disease (HD) is an inherited autosomal dominant neurodegenerative disorder caused by an expansion of a CAG trinucleotide repeat in the huntingtin (HTT) gene [Huntington's Disease Collaborative Research Group (1993) A novel gene containing a trinucleotide repeat that is expanded and unstable on Huntington's disease chromosomes. The Huntington's Disease Collaborative Research Group. Cell, 72, 971-983]. Despite identification of the gene in 1993, the underlying life-long disease process and effective treatments to prevent or delay it remain elusive. In an effort to fast-track treatment strategies for HD into clinical trials, we have developed a new large-animal HD transgenic ovine model. Sheep, Ovis aries L., were selected because the developmental pattern of the ovine basal ganglia and cortex (the regions primarily affected in HD) is similar to the analogous regions of the human brain. Microinjection of a full-length human HTT cDNA containing 73 polyglutamine repeats under the control of the human promotor resulted in six transgenic founders varying in copy number of the transgene. Analysis of offspring (at 1 and 7 months of age) from one of the founders showed robust expression of the full-length human HTT protein in both CNS and non-CNS tissue. Further, preliminary immunohistochemical analysis demonstrated the organization of the caudate nucleus and putamen and revealed decreased expression of medium size spiny neuron marker DARPP-32 at 7 months of age. It is anticipated that this novel transgenic animal will represent a practical model for drug/clinical trials and surgical interventions especially aimed at delaying or preventing HD initiation. New sequence accession number for ovine HTT mRNA: FJ457100.

Brain urea increase is an early Huntington’s disease pathogenic event observed in a prodromal transgenic sheep model and HD cases

“…In agreement with the HD postmortem brain analysis, significantly elevated postmortem brain urea levels were found in the transgenic HD sheep model OVT73. The OVT73 sheep is the only large animal model that expresses full-length mutant (73 glutamines) human huntingtin (17). The OVT73 sheep are considered a prodromal model system since they display no overt symptoms of the disease or cell loss (19), despite the presence of a recognized pathologic correlate, namely huntingtin-positive aggregates (18), as well as altered metabolite levels (20), and a circadian rhythm disruption measurable by Global Positioning System tracking (19).…”

“…The transgenic sheep line OVT73 expresses full-length human huntingtin with a pathogenic exon 1 glutamine repeat of 73 units, under the regulatory control of a short human genomic HTT upstream sequence (17). The OVT73 sheep display some of the neuropathological changes that occur in HD, including the accumulation of intracellular huntingtin-positive inclusions (18).…”

Gene Therapy of Some Genetic Diseases by Transferring Normal Human Genomic DNA into Somatic Cells and Stem Cells from Patients

“…There are transgenic mouse, sheep and monkey models available for conducting animal experiments currently (Bates et al, 1997;Beilby, 2007;S. Davies & Ramsden, 2001;Jacobsen et al, 2010;MacDonald et al, 1993;Yang et al, 2008).…”

In Vivo Gene Transfer in the Female Bovine: Potential Applications for Biomedical Research in Reproductive Sciences

“…For instance, pig and sheep species have been used as models for cardiovascular disease (Ishii et al, 2006), wound repair (Graham et al, 2000), respiratory disease (Scheerlinck et al, 2008), cancer (Du et al, 2007), diabetes (Dyson et al, 2006), ophthalmological disorders (Klassen et al, 2008) and neurological dysfunctions (Kragh et al, 2009). The physiology, organ size, genome organization, life span and pathology of farm animal species reflect the human situation much better than rodent models (Casal & Haskins 2006;Habermann et al, 2007;Jacobsen et al, 2010;Muschler et al, 2010). Implementation of in vivo gene transfer technology in relevant large animal models is pivotal to elucidate molecular pathways involved in reproductive processes such as ovarian involves the in vitro transfer of exogenous genetic material into cells followed by the in vivo delivery of the genetically modified cell into the target tissue (Yang, 1992;Stribley et al, 2002;Gardlík et al, 2005).…”