Addressing neurons methylomics in multiple sclerosis

Question 1

What is the use of utilizing DNA methylation for multiple sclerosis and what information can it give (3 things)?

Answer 1

Could uncover processes that take place in the CNS of MS patients

1. Regulate gene expression in a time- and space-specific manner
2. Provide complement information to the DNA sequence
3. Mediate phenotypic plasticity in response to external signals

Question 2

What are the 3 properties making DNA methylation a good study tool?

Answer 2

1. Stable throughout time => easy to study, informative
2. Sensitive to external factors => reflect the impact of the environment
3. Reversible => possible to treat (epigenetic drugs)

Question 3

What were the previous limitations in bulk tissue studies?

Answer 3

• Not cell-type specific

- ’True’ biological changes are hidden (because of epigenetic changes)

Question 4

What are 2 important considerations when using brain samples for tissue studies?

Answer 4

1. Need to select the most homogeneous brain tissue possible (neurons from subcortical white matter)
2. Need to correct for additional confounders (GABA vs GLU, neuronal sub-types, etc.)

Question 5

What is 5hmC?

Answer 5

• 5-Hydroxymethylcytosine, methylated form = 5mC
• Accumulation in adult neurons
• Role in neurodegeneration
• In MS: hypo-5mC and hyper-5hmC => reflect less transcriptional activity

Question 6

What does a decrease in 5mC and increase in 5hmC mean in multiple sclerosis?

Answer 6

• Impairs survival of post-mitotic neurons
• Gain of hydroxy-methylation (5hmC) associates with activation of genes involved in neurodegeneration, defects in neurite outgrowth and synaptic formation
• Leads to activation of specific endogenous retroviral elements (HERV) leading to apoptosis
  => May indicate epigenetic contribution to HERV-W expression in MS brain

Question 7

What is CREB and how does it associate with multiple sclerosis?

Answer 7

• CREB is a transcription factor involved in axonal regeneration, plasticity, cell survival, oxidative stress and
  neuroprotection
• DNA methylation changes in MS patients lowers the activity of CREB signaling pathways (CREB-associated neuro-axonal impairment)

Question 8

What could be a targeted therapy for epigenetics?

Answer 8

CRISPR/dCas9 epigenome editing

Question 9

What are some challenges/difficulties on epigenetic studies for multiple sclerosis?

Answer 9

• Hard to match patients with controls for age, sex, risk factors, etc.
• Expensive experiments
• Hard to interpret epigenetic marks (complex)
• Technical challenges (separate cell types, sub-types, etc.)
• Tissues are already too degraded for proper investigation
• Causality not always certain (environment/lifestyle)
  …