Genome complexity: RNA editing (Introduction)

by David Turell , Friday, February 21, 2020, 18:47 (1518 days ago) @ David Turell

A new layer of genome information controls found at the RNA level. The genome is so precise logically there are many more layers of the onion to be found:

https://sciencenorway.no/cells-dna-rna/rna-scientists-have-discovered-a-new-layer-in-th...

"Although genes themselves don’t change, they can be regulated.

"They are turned on and off as we grow and develop. These changes are influenced by our surroundings, so we actually change over the course of our lives. And some of these changes in regulation are passed on to our children.

"Figuratively speaking, our DNA can be described as the recipe book for who and how we are, while epigenetic regulation can be seen as notes that have been pencilled into the margin.

"Epigenetics thus describes a fascinating layer of information and regulation of our genes that enables us to adapt to new environments much faster than via normal evolution.
But lately, scientists have seen evidence of something more.

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"Initially, researchers thought that RNA worked like a dutiful but slightly boring cook, one that follows the recipe exactly.

But lately, scientists have begun to rethink this idea. RNA appears to be making its own modifications to the DNA recipes.

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"...several research groups had devised techniques for mapping and investigating a type of RNA modification, called 6-methyladenine (m6A).

"Three different studies, including one that Klungland was involved in, made it clear that these changes could be turned on and off.

"The m6A tags were attached to specific regions of RNA and appeared to be important. Attaching and removing m6A at the right time seemed to be absolutely necessary in some situations, such as in foetal development.

"Gradually, more and more scientists have begun to believe in the existence of something they call epitranscriptomics — that is, epigenetics for RNA, which in turn affects how the information in our DNA is used in practice.

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“'Together, these new studies reveal a whole new level of gene expression regulation,” wrote Margarita Angelova and her colleagues in Frontiers in Bioengineering and Biotechnology in 2018.

At the same time, researchers have warned that so far, we know very little about what these modifications are doing.

"In addition to m6A, researchers have found about 150 other alterations to RNA. Klungland agrees that there’s a lot we don’t know, such as what actually controls these alterations.
"Epigenetic changes in DNA are clearly influenced by the environment, but we do not know if this is the case with modifications in RNA," he says. “I wouldn't be surprised if the environment was also controlling RNA modification, but this is difficult to study.”

"Unlike DNA, RNA in a cell is volatile. The RNA molecules are formed and dissolved in one go. This makes it much more difficult to assess them to find out how they behave and what affects them.

“But it’s conceivable that these RNA modifications are a way to make rapid, temporary changes in how genes are expressed,” says Klungland.

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"Klungland and his colleagues have recently published research showing that modifications to RNA must be correct for DNA to work.

"A special m6A modification is needed when RNA separates the strands in DNA and copies a recipe. But it is equally important that the tag be removed again afterwards. If not, the DNA can be damaged.

Both mice and humans get sick if RNA tags aren’t added and removed at the right time, he said.

“'This can lead to both cancer and neurodegenerative disease,” Klungland says.
When he and his colleagues did an experiment where RNA modifications were not read properly, it turned out that fertilized eggs in live mice were unable to develop.

"This means that changes in RNA are a fundamental function of the body. A fundamental mechanism that was completely unknown just a few years ago."

Comment: Biochemistry in living organisms is precisely controlled. One simple example is the sodium level in blood never changes, despite what you eat or drink. All of the controls in the body are this precise, automatic, no cellular intelligence involved just following instructions from the layers of information in the genome through molecular reactions.