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A patient-derived cellular model for Huntington's disease reveals phenotypes at clinically relevant CAG lengths
Claudia Lin-Kar Hung1, Tamara Maiuri1, Laura Erin Bowie1
1Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada.
Insights
Researchers developed TruHD cells, a new human cell model for Huntington's disease (HD). These cells accurately reflect patient disease characteristics, aiding in understanding HD mechanisms and potential therapies.
Area of Science:
- Neuroscience
- Genetics
- Cell Biology
Background:
- Huntington's disease (HD) involves expanded CAG repeats in the huntingtin gene, disrupting cellular functions.
- Existing cell models often use synthetic CAG lengths or have limited lifespans, hindering comprehensive HD research.
Purpose of the Study:
- To generate a clinically relevant, immortalized human cell model for studying Huntington's disease mechanisms.
- To overcome limitations of patient-derived fibroblasts and synthetic cell lines for HD research.
Main Methods:
- Immortalization of patient-derived fibroblasts using human telomerase reverse transcriptase (hTERT) to create TruHD cells.
- Characterization of TruHD cells for Huntington's disease-specific phenotypes.
Main Results:
- TruHD cells exhibit key HD phenotypes: altered morphology, growth, oxidative stress sensitivity, and aberrant ADP/ATP ratios.
- Observed dysregulated reactive oxygen species (ROS)-dependent huntingtin localization to nuclear speckles.
- TruHD cells maintain critical functions for huntingtin's role in transcriptional regulation and genomic integrity.
Conclusions:
- TruHD cells provide a robust, clinically relevant human cellular model for single-cell level investigation of Huntington's disease.
- This model overcomes limitations of previous cell lines, offering new avenues for understanding HD pathogenesis and therapeutic development.
Abstract:
The huntingtin protein participates in several cellular processes that are disrupted when the polyglutamine tract is expanded beyond a threshold of 37 CAG DNA repeats in Huntington's disease (HD). Cellular biology approaches to understand these functional disruptions in HD have primarily focused on cell lines with synthetically long CAG length alleles that clinically represent outliers in this disease and a more severe form of HD that lacks age onset. Patient-derived fibroblasts are limited to a finite number of passages before succumbing to cellular senescence. We used human telomerase reverse transcriptase (hTERT) to immortalize fibroblasts taken from individuals of varying age, sex, disease onset, and CAG repeat length, which we have termed TruHD cells. TruHD cells display classic HD phenotypes of altered morphology, size and growth rate, increased sensitivity to oxidative stress, aberrant adenosine diphosphate/adenosine triphosphate (ADP/ATP) ratios, and hypophosphorylated huntingtin protein. We additionally observed dysregulated reactive oxygen species (ROS)-dependent huntingtin localization to nuclear speckles in HD cells. We report the generation and characterization of a human, clinically relevant cellular model for investigating disease mechanisms in HD at the single-cell level, which, unlike transformed cell lines, maintains functions critical for huntingtin transcriptional regulation and genomic integrity.