Consistent decrease in global DNA methylation and hydroxymethylation in the hippocampus of Alzheimer's disease patients
Chouliaras L, Mastroeni D, Delvaux E, Grover A, Kenis G, Hof PR, Steinbusch HW, Coleman PD et al.. Neurobiology of aging, 2013-04-09
Topic: Genetics and APOE
Epigenetic dysregulation of gene expression is thought to be critically involved in the pathophysiology of Alzheimer's disease (AD). Recent studies indicate that DNA methylation and DNA hydroxymethylation are 2 important epigenetic mechanisms that regulate gene expression in the aging brain. However, very little is known about the levels of markers of DNA methylation and hydroxymethylation in the brains of patients with AD, the cell-type specificity of putative AD-related alterations in these markers, as well as the link between epigenetic alterations and the gross pathology of AD. The present quantitative immunohistochemical study investigated the levels of the 2 most important markers of DNA methylation and hydroxymethylation, that is, 5-methylcytidine (5-mC) and 5-hydroxymethylcytidine (5-hmC), in the hippocampus of AD patients (n = 10) and compared these to non-demented, age-matched controls (n = 10). In addition, the levels of 5-hmC in the hippocampus of a pair of monozygotic twins discordant for AD were assessed. The levels of 5-mC and 5-hmC were furthermore analyzed in a cell-type and hippocampal subregion-specific manner, and were correlated with amyloid plaque load and neurofibrillary tangle load. The results showed robust decreases in the hippocampal levels of 5-mC and 5-hmC in AD patients (19.6% and 20.2%, respectively). Similar results were obtained for the twin with AD when compared to the non-demented co-twin. Moreover, levels of 5-mC as well as the levels of 5-hmC showed a significant negative correlation with amyloid plaque load in the hippocampus (r(p) = -0.539, p = 0.021 for 5-mC and r(p) = -0.558, p = 0.016 for 5-hmC). These human postmortem results thus strengthen the notion that AD is associated with alterations in DNA methylation and hydroxymethylation, and provide a basis for further epigenetic studies identifying the exact genetic loci with aberrant epigenetic signatures.
Key findings
- Recent studies indicate that DNA methylation and DNA hydroxymethylation are 2 important epigenetic mechanisms that regulate gene expression in the aging brain.
- The results showed robust decreases in the hippocampal levels of 5-mC and 5-hmC in AD patients (19.6% and 20.2%, respectively).
- Similar results were obtained for the twin with AD when compared to the non-demented co-twin.
- Moreover, levels of 5-mC as well as the levels of 5-hmC showed a significant negative correlation with amyloid plaque load in the hippocampus (r(p) = -0.539, p = 0.021 for 5-mC and r(p) = -0.558, p = 0.016 for 5-hmC).
- These human postmortem results thus strengthen the notion that AD is associated with alterations in DNA methylation and hydroxymethylation, and provide a basis for further epigenetic studies identifying the exact genetic loci with aberrant epigenetic signatures.
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Study details
- Effect size19.6%; 20.2%
- Evidence strengthLow
How this study scored 45/100
Published in a peer-reviewed journal. Scored zero for study design, sample size and randomised / blinded because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record and multi-centre collaboration, so those were left out: it earned 26 of the 58 points we could judge it on, which is 45 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Neurobiology of aging) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 1 / 5 | 2013 — within 20 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 2 / 3 | Effect reported as a number, without an interval or test |
| Studied in people | 3 / 3 | Studied in people (pubmed indexes it as a clinical or observational study) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 23582657) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 26 / 58 | Scored on 11 of 20 parts. We have no data for the rest, so they are left out: 26 of the 58 points we could judge it on is 45 out of 100. |
| Total | 45 / 100 | — |
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APA 7th
Chouliaras, L., Mastroeni, D., Delvaux, E., Grover, A., Kenis, G., Hof, P. R., et al. (2013). Consistent decrease in global DNA methylation and hydroxymethylation in the hippocampus of Alzheimer's disease patients. Neurobiology of aging. https://doi.org/10.1016/j.neurobiolaging.2013.02.021
Vancouver
Chouliaras L, Mastroeni D, Delvaux E, Grover A, Kenis G, Hof PR, et al. Consistent decrease in global DNA methylation and hydroxymethylation in the hippocampus of Alzheimer's disease patients. Neurobiology of aging. 2013. doi:10.1016/j.neurobiolaging.2013.02.021. PMID: 23582657.
BibTeX
@article{chouliaras2013-23582657,
author = {Chouliaras, L. and Mastroeni, D. and Delvaux, E. and Grover, A. and Kenis, G. and Hof, P. R. and Steinbusch, H. W. and Coleman, P. D. and others},
title = {{Consistent decrease in global DNA methylation and hydroxymethylation in the hippocampus of Alzheimer's disease patients}},
journal = {Neurobiology of aging},
year = {2013},
doi = {10.1016/j.neurobiolaging.2013.02.021},
pmid = {23582657},
url = {https://doi.org/10.1016/j.neurobiolaging.2013.02.021}
}