Oligonucleotides Targeting DNA Repeats Downregulate Gene Expression in Huntington's Patient-Derived Neural Model System.

Citation:
Umek, T., T. Olsson, O. Gissberg, O. Saher, E. M. Zaghloul, K. E. Lundin, J. Wengel, E. Hanse, H. Zetterberg, D. Vizlin-Hodzic, et al., "Oligonucleotides Targeting DNA Repeats Downregulate Gene Expression in Huntington's Patient-Derived Neural Model System.", Nucleic acid therapeutics, vol. 31, issue 6, pp. 443-456, 2021.

Abstract:

Huntington's disease (HD) is one of the most common, dominantly inherited neurodegenerative disorders. It affects the striatum, cerebral cortex, and other subcortical structures leading to involuntary movement abnormalities, emotional disturbances, and cognitive impairments. HD is caused by a CAG•CTG trinucleotide-repeat expansion in exon 1 of the () gene leading to the formation of mutant HTT (mtHTT) protein aggregates. Besides the toxicity of the mutated protein, there is also evidence that mt transcripts contribute to the disease. Thus, the reduction of both mutated mRNA and protein would be most beneficial as a treatment. Previously, we designed a novel anti-gene oligonucleotide (AGO)-based strategy directly targeting the trinucleotide-repeats in DNA and reported downregulation of mRNA and protein in HD patient fibroblasts. In this study, we differentiate HD patient-derived induced pluripotent stem cells to investigate the efficacy of the AGO, a DNA/Locked Nucleic Acid mixmer with phosphorothioate backbone, to modulate transcription during neural development. For the first time, we demonstrate downregulation of mRNA following both naked and magnetofected delivery into neural stem cells (NSCs) and show that neither emergence of neural rosette structures nor self-renewal of NSCs is compromised. Furthermore, the inhibition potency of both mRNA and protein without off-target effects is confirmed in neurons. These results further validate an anti-gene approach for the treatment of HD.