There has been increasing interest in the idea that lifestyle choices or stressful events during a person’s life might not just impact an individual at the time, but could send out a ripple that also affects their children. Known as “epigenetics,” the suggestion is that environmental factors and traumatic events can physically change the way a person's genes are expressed, and that this alteration can then be passed on if and when that person has children.
But a new study claims to have found that it’s not just changes to the DNA during a father’s life that can be passed on: Incredibly, changes to a particular protein associated with DNA can also be inherited, not just by their children but also their grandchildren.
“These findings are remarkable because they indicate that information other than DNA is involved in heritability,” says Sarah Kimmins, one of the lead authors of the paper published in Science.
Epigenetics has largely focused on how life events – from smoking to emotional and physical trauma – can change how and what genes in a person’s DNA are expressed. This expression, and thus the production of proteins, is generally controlled by what are known as methyl groups. These chemical tags attach to particular regions of DNA and act like a dimmer switch, turning up and down the rate at which certain genes are expressed. Evidence suggests that life events can alter where these methyl group attach to DNA, and that this can then be passed on from parent to child.
The new research, however, decided to focus on another aspect of DNA. When the vastly long molecule is ‘packaged’ into cells, DNA is wound around a particular protein called a histone, which effectively acts like a spool. Histones are able to control which sections of DNA get copied and expressed, depending on which parts of the thread are allowed to unravel. It’s already been established that environmental factors, such as diet and smoking, can change the structure of histones, but the researchers wanted to find out whether these changes had any impact on a father's children.
To test this, the researchers created mice in which they had altered the information that codes for the structure of histones during sperm cell formation, and then looked to see how this impacted their offspring. What they found was that these slight changes in the histones created offspring that were both more susceptible to birth defects and had lower rates of survival overall. In addition to that, the effect didn’t just directly impact the offspring, but was even felt two generations later.
"The study highlights the critical role that fathers play in the health of their children and even grand-children," explained Kimmins. "Since chemical modifications on histones are susceptible to environmental exposures, the work opens new avenues of investigation for the possible prevention and treatment of diseases of various kinds, affecting health across generations."
This fascinating piece of research adds yet another aspect to epigenetics. However, it’s important to note that while they might have been able to show that altered histones can impact offspring, and that histones can be modified by environmental factors, there is still a bridge missing between the two.
