DNA Methylation and Establishing Memory

Area of Science:

• Neuroscience
• Molecular Biology
• Epigenetics

Background:

• Memories are physically stored in neurons, with changes in gene expression being crucial for memory.
• Early theories suggested DNA methylation of cytosines encodes memories biochemically.
• Mammalian brain mechanisms for forming DNA methylcytosine encoded memories are under investigation.

Purpose of the Study:

• To review recent research on the molecular mechanisms of DNA methylcytosine encoded memory formation in the mammalian brain.
• To elucidate how neuronal gene expression changes contribute to long-term memory.

Main Methods:

• Review of current scientific literature on molecular memory mechanisms.
• Focus on DNA methylation and demethylation processes involving specific proteins and genes.
• Examination of neuron activation pathways and their epigenetic consequences.

Main Results:

• Neuron activation triggers DNA topoisomerase II beta (TOP2B) to create temporary DNA breaks, initiating demethylation at immediate early gene promoters like EGR1.
• EGR1 and TET1 proteins cooperate to demethylate hundreds of genes, facilitating their expression.
• OGG1 and TET1 also initiate demethylation at methylated CpG sites.
• Synaptic activity upregulates DNMT3A2, a gene encoding a protein that catalyzes de novo DNA methylation.

Conclusions:

• Multiple mechanisms involving DNA methylation and demethylation convert experiences into epigenetic changes in neurons.
• These epigenetic modifications alter gene expression, forming the basis of long-term memories.
• The interplay between DNA methylation and demethylation is central to memory consolidation.