The Principal Investigator

A recent paper from a consortium including researchers from the National Institute of Mental Health (NIMH), the Lieber Institute on Brain Development, and Johns Hopkins documents the DNA methylation pattern in the human prefrontal cortex across the lifespan. At first glance this article seems exceedingly technical and not of general interest. Now I may be biased because I study a disease (schizophrenia) with significant developmental aspects, but I believe this paper is full of incredible, novel findings on gene expression. The main points of this paper are concepts that we all should be concerned with. It gets to the crux of the age-old nature vs. nurture argument.

The study generally deals with a relatively new field of study known as epigenetics. Epigenetics deals with changes in gene expression, some potentially heritable, that do not include changes to the underlying DNA sequence. This particular article is concerned with DNA methylation. Long story short, DNA methylation leads to the silencing genes and subsequently less mRNA and protein produced by the silenced gene. More genes are silenced as we age. This makes since as development and growth, both physical and mental, should require the products of a greater number of genes. Interestingly, genes that become silenced as we age consist of many many integral players in what we consider “aging.” These include tumor suppressors and DNA repair genes.

We know that environmental experience can lead to epigenetic alterations that affect gene expression. For example, we know that maternal attention (licking, grooming, etc.) leads to epigenetic changes that facilitate anxiolytic responses in the offspring. This finding gets me to the title of this post: How much of what we now call environmental factors actually exert their effect through changes in gene expression. Potentially long-lasting changes in gene expression. I wonder how many experiences that we think are in our past, both positive and negative, that are still with us epigenetically?