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Hair dysmorphology in the R6/1 and R6/2 mouse models of Huntington's disease
Karolina Pierzynowska1, Magdalena Podlacha1, Dorota Łuszczek2
1Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
Insights
Huntington's disease (HD) mouse models, R6/1 and R6/2, exhibit previously undescribed hair abnormalities, including altered shape and increased diameter. This hair dysmorphology may serve as a novel, noninvasive marker for disease progression and therapeutic testing.
Area of Science:
- Genetics and Molecular Biology
- Neuroscience
- Animal Models
Background:
- Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by CAG repeat expansion in the HTT gene.
- While primarily neurodegenerative, HD affects peripheral tissues due to widespread HTT gene expression, leading to various symptoms.
- R6/1 and R6/2 mouse lines are widely utilized models for studying HD phenotypes.
Purpose of the Study:
- To identify and characterize novel phenotypic features in R6/1 and R6/2 Huntington's disease mouse models.
- To investigate hair morphology as a potential noninvasive biomarker for HD in these established mouse models.
Main Methods:
- Comparative analysis of hair morphology between R6/1 and R6/2 mice and control groups.
- Utilized electron microscopy to assess detailed hair structure, including surface topography and scale integrity.
- Measured hair diameter and evaluated pelage appearance.
Main Results:
- Significant hair dysmorphology was observed in both R6/1 and R6/2 HD mouse models.
- Hair diameter was significantly increased in HD models compared to controls.
- Electron microscopy revealed altered hair surface (deep cavities, hilly texture, flattened appearance) and loosened scale structures.
Conclusions:
- Hair morphology represents a novel, previously undescribed feature in R6/1 and R6/2 Huntington's disease mouse models.
- Hair abnormalities, including shape and diameter changes, may serve as a simple, noninvasive marker for assessing HD progression.
- This finding could be valuable for evaluating the efficacy of potential therapeutics in preclinical HD research using these mouse models.
Abstract:
Huntington's disease (HD), caused by expansion of CAG repeats in the 1st exon of the HTT gene, is a disorder inherited in an autosomal dominant manner. HD symptoms include chorea, behavioral disturbances and cognitive decline. Although it is described as a neurodegenerative disease, due to expression of HTT in all types of cells, peripheral symptoms also occur. R6/1 and R6/2 mouse lines, which demonstrate many different phenotypical disturbances, are among the most commonly used HD animal models. Nevertheless, in this report, we underlined, for the first time, a previously undescribed R6/1 and R6/2 feature, hair dysmorphology. We observed changes in the general view of pelage, as well as specific changes in the shape of hair, assessed under electron microscope (deep cavity and hilly hair surface or concave and convex areas on the long hair axis with an appearance of the hair as flat). Hair diameter was significantly increased in both HD mouse models relative to control animals. Moreover, loosened contact between the scales and loosened scale texture were observed in R6/1 and R6/2. Thus, this study highlighted that the hair morphology might be a useful, noninvasive and simple marker of a widely used HD mouse models, R6/1 and R6/2 lines, particularly in testing effects of potential therapeutics or disease progression.
