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Updated: Aug 13, 2025
The Detection of 5-Hydroxymethylcytosine in Neural Stem Cells and Brains of Mice
Published on: September 19, 2019
5-Methylcytosine and 5-Hydroxymethylcytosine in Scrapie-Infected Sheep and Mouse Brain Tissues
Adelaida Hernaiz1, Sara Sentre1, Marina Betancor2
1Laboratorio de Genética Bioquímica (LAGENBIO), Facultad de Veterinaria, Universidad de Zaragoza, IA2, IIS Aragón, 50013 Zaragoza, Spain.
Abstract:
Scrapie is a neurodegenerative disorder belonging to the group of transmissible spongiform encephalopathies or prion diseases, which are caused by an infectious isoform of the innocuous cellular prion protein (PrPC) known as PrPSc. DNA methylation, one of the most studied epigenetic mechanisms, is essential for the proper functioning of the central nervous system. Recent findings point to possible involvement of DNA methylation in the pathogenesis of prion diseases, but there is still a lack of knowledge about the behavior of this epigenetic mechanism in such neurodegenerative disorders. Here, we evaluated by immunohistochemistry the 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) levels in sheep and mouse brain tissues infected with scrapie. Expression analysis of different gene coding for epigenetic regulatory enzymes (DNMT1, DNMT3A, DNMT3B, HDAC1, HDAC2, TET1, and TET2) was also carried out. A decrease in 5mC levels was observed in scrapie-affected sheep and mice compared to healthy animals, whereas 5hmC displayed opposite patterns between the two models, demonstrating a decrease in 5hmC in scrapie-infected sheep and an increase in preclinical mice. 5mC correlated with prion-related lesions in mice and sheep, but 5hmC was associated with prion lesions only in sheep. Differences in the expression changes of epigenetic regulatory genes were found between both disease models, being differentially expressed Dnmt3b, Hdac1, and Tet1 in mice and HDAC2 in sheep. Our results support the evidence that DNA methylation in both forms, 5mC and 5hmC, and its associated epigenetic enzymes, take part in the neurodegenerative course of prion diseases.
Insights
DNA methylation (5mC and 5hmC) and epigenetic enzymes are involved in prion diseases like scrapie. Studies in sheep and mice show altered DNA methylation patterns and gene expression during scrapie infection.
Area of Science:
- Neuroscience
- Epigenetics
- Molecular Biology
Background:
- Scrapie is a prion disease affecting the central nervous system.
- DNA methylation is crucial for brain function and may play a role in prion disease pathogenesis.
- The specific epigenetic changes in scrapie are not well understood.
Purpose of the Study:
- To investigate DNA methylation (5mC and 5hmC) levels in scrapie-infected sheep and mouse brains.
- To analyze the expression of genes encoding epigenetic regulatory enzymes in these models.
- To understand the role of DNA methylation in the neurodegeneration caused by scrapie.
Main Methods:
- Immunohistochemistry was used to assess 5mC and 5hmC levels in brain tissues.
- Gene expression analysis was performed for epigenetic regulatory enzymes (DNMT1, DNMT3A, DNMT3B, HDAC1, HDAC2, TET1, TET2).
- Scrapie-infected and healthy sheep and mouse models were utilized.
Main Results:
- Scrapie infection led to decreased 5mC levels in both sheep and mice.
- 5hmC levels decreased in sheep but increased in preclinical mice.
- 5mC correlated with prion lesions in both species, while 5hmC correlated only in sheep.
- Differential expression of epigenetic genes (Dnmt3b, Hdac1, Tet1 in mice; Hdac2 in sheep) was observed.
Conclusions:
- DNA methylation, in both 5mC and 5hmC forms, is implicated in the neurodegenerative process of prion diseases.
- Epigenetic regulatory enzymes are also involved and show differential expression patterns.
- These findings highlight the complex role of epigenetics in scrapie pathogenesis.
