Somatic DNA-repeat expansions initiate distinct yet analogous changes in Huntington's disease cortical and striatal neurons
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Updated: Oct 30, 2026

Efficient and Scalable Production of Full-length Human Huntingtin Variants in Mammalian Cells using a Transient Expression System
Published on: December 10, 2021
Seva Kashin1, Won-Seok Lee1, Tara M McDonald1
1Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
Abstract:
Huntington's disease (HD) affects the neocortex and striatum with different timing, severity, and gene-expression changes. These pathologies have long been proposed to involve different pathogenic mechanisms, with one brain area's degeneration leading to the other's. Striatal neurons degenerate in HD as their huntingtin (HTT) CAG-repeat tracts expand somatically beyond 150 CAGs. Here, we find that cortical pyramidal neurons in HD undergo biological changes analogous to those in striatal neurons-the same sequence of pathological phases, with toxicity also commencing at ∼150 CAGs but then changing their gene expression in distinct ways. Pyramidal neurons' precise molecular identities, rather than their areal or laminar locations, appeared to determine the extent of this somatic DNA-repeat expansion, which varied up to 20-fold among pyramidal neuron subtypes. Cortical and striatal neurons also shared a key pathological feature: nuclear inclusions of aggregated HTT protein in those nuclei with expansions well beyond 150 CAGs.
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