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Check out our new publication in Plos Genetics!

23 October 2015 Author: Eka Suchiman

How is it possible that all different organs and tissues in the body contain the same DNA molecule? A publication in the renowned scientific journal PLoS Genetics of October 22 solves some of this mystery by investigating for the first time epigenetic changes during fetal development. The research of our epigenetics group led by Bas Heijmans in collaboration with the group of Susana Chuva de Sousa Lopes (Anatomy and Embryology, LUMC) shows how in each tissue, developmental genes are gradually turned off, while genes that are required are turned on.

The human body is made up of hundreds of different types of tissues and cells. All of these tissues and cells contain the same DNA. To get different cells, epigenetic modifications instruct which part of the DNA must be active. Which parts are active differs in each cell type. DNA methylation is a key epigenetic modification. In the current study we have investigated for the first time the DNA methylation changes during the first and second trimester of human development. The researchers studied four tissues: muscle, adrenal, pancreas and the amnion that surrounds the fetus. Already in the first trimester, a tissue-specific signature was found in each of the tissues. However, during the first and second trimester, a substantial number of genomic regions were found to gain and lose DNA methylation. Genomic regions that gained methylation were associated with the shut-down of developmental processes, while genomic regions that lose methylation were associated with the activation of tissue-specific functions. The latter occurred on genomic regions that regulate genes over a large distance. Roderick Slieker, together with Matthias Roost first author on the article: ‘Our research sheds light on the genomic regions that are important for a healthy development. Those are the regions where to look when normal development fails’. Heijmans adds: ‘We think for example that adverse conditions in the womb can lead to epigenetic defects and hence to health problems in later life’.