The database also includes thousands of new biomarkers that will make it possible to detect cell death and to diagnose in the early stages a variety of diseases in the most important systems of the human body, through a blood test
In a new study, conducted by researchers at the Hebrew University and the Hadassah Medical Center, the researchers were able to map the way in which the DNA is marked in dozens of cell types in the human body, including the immune system, the blood, the respiratory system and the heart. The findings, published today in the prestigious journal Nature, identify genomic regions that are responsible for gene silencing and activation, and will promote innovative methods for diagnosing complex diseases. The research was carried out in collaboration between Prof. Tomi Kaplan from the School of Engineering and Computer Science, Prof. Yuval Dor and Dr. Yehudit Magnheim from the School of Medicine at the Hebrew University, doctoral students Nathaniel Loefer and Ayelet Peretz, as well as Prof. Ben Glazer and other doctors from the Hadassah Medical Center, and in collaboration With the American biotechnology company Grail, which specializes in the early detection and diagnosis of cancers through blood tests.
"All the cells in our body originate from one and the same cell, and they all contain the same DNA sequence, which encodes the operating instructions for all types of cells in the body, healthy and sick," explains Prof. Dor. "However, each type of cell knows how to activate only the genes it needs to function properly. Already in the XNUMXs, in the pioneering work of Prof. Haim Sider and the late Prof. Aharon Razin, it became clear that this control is achieved by methylation - chemical marking of the DNA at specific sites using a methyl group (carbon and three hydrogens) - which silences the genes that are not supposed to be in use ". However, the mechanisms responsible for the silencing and activation of genes, including the genomic regions that are essential for the function and identity of each type of cell in the human body, have not yet been fully deciphered.
Using advanced DNA sequencing technology, the team of researchers determined the DNA methylation model, that is, the areas where a methyl group was added, in dozens of healthy cell types in the human body. This information allowed researchers to identify for the first time thousands of DNA sequences that control the expression of the most important genes in each cell type. "Previous studies focused on whole tissues that consist of several types of cells, while now, thanks to the efficiency of the mapping and analysis of the DNA molecule - the new genomic atlas consists of individual cell types. This allowed us to identify thousands of regions in the genome that are uniquely marked in each cell type. These areas can be used as new biomarkers, thus assessing the composition of cell types in a biological tissue or blood sample with an unprecedented level of precision," Prof. Kaplan shares.
Prof. Glazer explains that the new findings will make it possible to diagnose diseases using a simple blood sample: "When a cell in our body dies, it releases DNA fragments that reach the bloodstream. The technology we developed can analyze the methylation pattern on the DNA fragments (a method called "liquid biopsy"), and thus determine which types of cells they came from. This information makes it possible to estimate how many and which cells died in our body in the hours preceding the blood sampling." In the future, the technology will make it possible to diagnose damage to important systems in the body, including the respiratory system and the heart, as well as early identify various diseases such as Alzheimer's, cancer, liver diseases, and others.
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With all due respect to Prof. Haim Sider and the late Prof. Aharon Razin, "Historically, DNA methylation was discovered in mammals as early as DNA was "identified as the genetic material (Avery et al, 1944; McCarty and Avery, 1946). i
מקור: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3521964/