Teach the epigenome!
Decoding of the first epigenome in Europe has been completed
ABC magazine based on the materials of IDIBELL: First epigenome in Europe completed
Manel Esteller, Professor of Genetics at the University of Barcelona, director of the Epigenetics and Cancer Biology Program at the Biomedical Research Institute in Bellvitge (IDIBELL-Bellvitge Biomedical Research Institute), has completed the decoding of the first epigenome in Europe. The results of his work are published in the journal Epigenetics (Heyn et al., Whole-genome bisulfite DNA sequencing of a DNMT3B mutant patient).
The genome of all cells of the human body is the same, regardless of their structure and function. Therefore, the cellular genome alone cannot explain the different activity of various organs and tissues, as well as the mechanisms of the development of pathologies in them during the development of diseases, including cancer. There are other factors that determine which of the genes that make up the genome work and which are disabled. These factors are combined into the concept of "epigenome". Such factors may include, for example, the spatial configuration of the DNA "double helix" and its methylation.
It is methylation, i.e. the addition of a methyl group (–CH 3) to DNA, that is the most well-known and important epigenetic factor. Last year, American scientists managed not only to detect methyl groups in the DNA molecule for the first time, but also to draw up a diagram of their location in the genome under study. Then the researchers of the Genomic Analysis Laboratory at the Salk Institute deciphered the epigenome of human embryonic stem cells and lung connective tissue cells (fibroblasts). It turned out that in the fibroblast genome, most methyl radicals are located next to cytosine, and in the DNA of stem cells – next to other elements of the double helix.
Dr. Esteller chose white blood cells of two girls as an object for observation – healthy and suffering from a rare genetic disease – ICF syndrome (from the English Immune deficiency – immunodeficiency, Centromeric instability – instability of centromeric heterochromatin, Facial dysmorphism – facial anomalies). Deciphering the epigenome of the sick girl, he found that this rare disease is caused by a mutation in the gene, which leads to the appearance of an additional methyl group in the DNA localized in the centromere. As a result, the chromosomes become fragile and can easily disintegrate. It was also found that due to hypermethylicity (an additional methyl group), control over the genes responsible for fighting infection is disrupted. Because of this, patients with ICF syndrome suffer from severe immunodeficiency. According to Dr. Esteller, decoding the epigenome not only helps to better understand how genetic diseases develop, it will also help to develop strategies for the treatment of such pathologies. In addition, he is sure that the basis for the development of any cancerous tumor in humans is a common epigenetic factor: hypermethylicity of DNA genes responsible for suppressing tumor growth.
Graphical distribution of two identified epigenomes:
the dark blue circle refers to a healthy person, the blue circle refers to a patient.
© IDIBELL-Bellvitge Biomedical Research Institute.
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