Monday, August 07, 2017 by Isabelle Z.
A groundbreaking study has demonstrated that people inherit more than just genes from their parents, shattering long-held beliefs by some that we are simply the sum of our genes.
It was already known that epigenetic mechanisms that are modulated by environmental cues like disease, lifestyle and diet can switch genes on and off, but there has been a great deal of debate about whether these modifications can be passed along to future generations.
Researchers from the Max Planck Institute of Immunobiology and Epigenetics now have the answer to this question. They have shown that it’s not just inherited DNA that regulates gene expression in human offspring; it’s also inherited epigenetic instructions.
In addition, scientists have shed light on the biological consequences of this inherited information, proving that a mother’s epigenetic memory plays a vital role in her offspring’s development and survival.
Epigenetic modifications can be thought of as labels that tell specific DNA regions to attract or resist proteins that activate genes. Unlike the fixed letter sequences of DNA, epigenetic marks change throughout a person’s life in response to lifestyle, stress, environment and other factors. Smoking, for example, can change lung cells’ epigenetic makeup and eventually spur cancer.
Until recently, scientists believed that epigenetic memory that is accumulated throughout a person’s lifetime is essentially cleared out when sperm and egg cells are developed and they never pass into the next generation. A few recent studies have started to point to the possibility of epigenetic marks being transmitted across generations, but how this occurs and what effects they have on the offspring was not understood.
A study team led by Nicola Iovino used fruit flies to examine the way a mother transmits these epigenetic modifications to the embryo. For the study, they focused on a modification that is also seen in humans, H3K27me3, which alters DNA packaging in the cell nucleus and is linked with the repression of gene expression.
The researchers discovered that the H3K27me3 modifications in the mother’s egg cells were also in the embryo after it had been fertilized, despite the fact that other epigenetic marks were erased. After confirming that the mother does indeed pass epigenetic marks to the offspring, they set out to find out if these marks serve a useful function in the embryo.
They found that when they removed the enzyme that places the H3K27me3 marks in the embryos during early development, the embryos failed to develop completely. This indicates that the epigenetic information is vital for the embryo’s development.
It is now clear that inherited epigenetic information has important biological consequences. Moreover, because disrupting epigenetic mechanisms can lead to diseases like autoimmune disorders and cancer, their finding could have a significant impact on human health. For example, we already know that a mother’s nutrition level at the moment of conception can influence the way her child’s genes are interpreted, creating an impact that can last a lifetime.
This finding underscores the importance of maintaining a healthy lifestyle when trying to conceive. Eating healthy foods is only part of the equation; it’s also vital to avoid toxins found in food (like pesticides), beauty products, and the environment to give your future children the best chance in life.