Genome complexity: epigenetic control of gene expression (Introduction)

by David Turell , Wednesday, March 01, 2023, 18:33 (423 days ago) @ David Turell

One specific molecule at work:

https://medicalxpress.com/news/2023-03-unveils-epigenetic-traffic-gene.html

"Scientists at The Institute of Cancer Research, London, reveal how a key epigenetic signal called H3K4me3—determines when and how DNA should be read and translated into proteins within our cells.

"The study shows that H3K4me3 ensures genes are transcribed and activated at the right time in a controlled manner, like a set of traffic lights regulating the flow of cars on a busy road. Understanding how it functions in normal cells can also shed new light on the development of cancer—and the role played by a breakdown in the regulation of gene activity.

"It has been known for more than 20 years that the enzymes placing H3K4me3, a chemical tag added to DNA, are crucial for normal cell development, as well as being linked to leukemia, breast, bowel and pancreatic cancers. But, until now, scientists lacked an understanding of what the chemical tag does, despite many years of research.

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"Epigenetics affects gene activity, or expression, without changing the underlying genetic code—for example, by adding or removing chemical tags or modifications to DNA or proteins that the DNA is wrapped around, called histones. Chemical modifications such as H3K4me3 (tri-methylation of histone H3 lysine 4) can turn genes on or off, and are often altered in cancer.

"Using mouse stem cells and sophisticated genetic and biochemical experiments in the lab, researchers found that the H3K4me3 modification is essential for regulating how and when our genes are expressed.

"The team found that H3K4me3 acts like a traffic light at a busy intersection. By regulating the flow of RNA polymerase II—a protein complex that reads and decodes DNA—H3K4me3 determines when gene expression should start and the speed at which it runs.

"When it gives the green light, H3K4me3 allows RNA polymerase II to move along DNA, transcribing it into RNA as it moves. But without H3K4me3, RNA polymerase II gets stuck at specific points on the DNA, creating a hold-up and slowing down transcription.

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"Study leader Professor Kristian Helin, Chief Executive of The Institute of Cancer Research, London, and a world leader in the study of epigenetics, said, "Our study offers a fundamental new understanding of epigenetics, a very exciting and still largely underexplored area of cancer research. We have solved a 20-year-old puzzle by discovering how a well-known epigenetic modification controls gene expression. Because the enzymes determining the level of H3K4me3 in the cell frequently are found mutated in cancer, our studies could have implications for understanding and treating cancer.'"

Comment: this is from research into how cancer develops. Natural processes must be understood first. Recognizing this is an automatic process, it is still not clear what influences the molecule into action.