If a father works out every night and day at the gym, will he have a brawny baby? Well, yes and no. It might sound Lamarckian but the French naturalist might have had a point. A team of researchers from the University of Cambridge has described for the first time in humans how some regions of the epigenome are, in fact, delivered to the offspring.
Although our genetic information is written in the four letters of the DNA, our genes are annotated, the same way this text is punctuated. The genetic commas and points embody the epigenome, which regulate and even switch on and off our genes.
These annotations have several forms. Broadest studies focus on methylation, where small methyl molecules attach to the DNA, contributing to the regulation of gene activity. Methylation occurs spontaneously through our interaction with the environment, for example in periods of deprivation of nutrients. Almost all of this epigenetic information is, however, removed in early germ cells prior to the generation of egg and sperm. Yet, researchers from the University of Cambridge have recently discovered that some regions of our genome resist to this reprogramming.
In a study funded primarily by the Wellcome Trust, Professor Azim Surani and colleagues showed that, during the erasing process, a genetic network inhibits the enzymes that maintain the epigenome until the DNA is almost clear of its methylation patterns. However, researchers also found out that this process does not clean the entire epigenome: around 5% of our DNA defies reprogramming. These ‘escapee’ regions of the genome contain some genes associated with conditions such as schizophrenia, metabolic disorders and obesity.
These defiant genes are particularly active in neuronal cells, so this resistance may have a role during development. These particular regions have also been found in mice, which will facilitate the study of its function in greater detail. In the meantime, we might owe an apology to the poor and vilified Lamarck.