It has long been known that the DNA of a parent is the main health determinant and disease in children. However, inheritance via DNA is not everything: a father’s lifestyle such as diet, overweight and stress have been linked to consequences on the health of his offspring. This phenomenon occurs through the epigenome, when the environment has an influence on the genome (all the genetic material of a cell) by so-called epigenetic modifications. But the way the information is transmitted during fertilization, and the exact mechanisms and molecules of the sperm involved in this process have not been clear until now.
A new study by researchers at McGill University, published in the journal Developmental Cell, has made progress in this area by identifying how environmental information is transmitted by non-DNA molecules in semen. An important discovery because it potentially opens up new avenues for studying disease transmission and prevention. “The great advancement of this study is that it identified a non-DNA-based means by which sperm remember environment (diet) of a father and transmit this information to the embryo. », Explains Professor Sarah Kimmins, lead author of the study.
Changes in semen proteins affect the offspring
She adds: “It is remarkable, because the study presents a major change from what we know on heritability and disease, which is solely based on DNA, to a system that now includes semen proteins. Until now, no scientific team has been able to know how these hereditary environmental signatures are transmitted from sperm to the embryo before. According to the researchers, “it was very difficult to work at the molecular level of the embryo because you have so few cells available for epigenomic analysis. It is only thanks to new technologies and epigenetic tools that we have been able to achieve these results. “
To determine how information that affects development are transmitted to embryos, the researchers manipulated sperm by feeding male mice a diet deficient in folate (vitamin B9). The latter has an essential role in the production of genetic material (DNA, RNA) and amino acids necessary for cell growth, which explains its essential character during the different phases of life. The researchers then mapped out the effects on particular groups of molecules in proteins associated with DNA, and then discovered induced changes. by diet on molecules of the methyl family.
Together with histone proteins, essential for packaging DNA in cells, these changes themselves lead to changes in gene expression in embryos, and birth defects of the spine and the skull at birth. In addition, these changes in the histones of the sperm are transmitted during fertilization and remain in the developing embryo. “The hope offered by this work is that by expanding our understanding of what is inherited beyond DNA, there are potential pathways for disease prevention that will lead to healthier children and adults. », Conclude the researchers.