Genome complexity: more epigenetic coding sites on RNA (Introduction)

by David Turell , Tuesday, August 13, 2019, 15:39 (1719 days ago) @ David Turell

More work on m6A on RNA's:

https://phys.org/news/2019-08-mysterious-m6a-rna-yield-secrets.html

"Modifications called N6–methyladenosine, or m6A marks, are made by enzymes on the RNA transcripts of some human genes under certain conditions, but the functions of these marks have been largely mysterious. The research team, in a study that appeared online in Nature on July 10, found that m6A marks can cause m6A-containing RNAs to be stored in special, droplet-like compartments in cells. Normally these RNAs would be translated into proteins by the cells' protein-making machinery, but their sequestration in the droplet-like compartments effectively blocks protein production. The scientists found evidence that one important context for this RNA-sequestering action is when a cell is being damaged or otherwise stressed.

"'Our findings suggest that a major function of m6A marks is to induce the storage of certain RNAs during cellular stress," said senior author Dr. Samie Jaffrey, the Greenberg-Starr Professor of Pharmacology at Weill Cornell Medicine. "A lot of these m6A-marked RNAs encode cellular repair proteins, so it appears that cellular repair processes are suppressed in this way during stress, but then un-repressed when the damage has stopped and it becomes appropriate for repairs to start."

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"[They]began their new study by examining three proteins called YTHDF proteins, which naturally bind to m6A marks on RNAs. The scientists found that the YTHDF proteins have properties that make them tend to stick together when multiple copies are present on m6A-marked RNAs. This clustering causes the YTHDF proteins and their attached m6A-containing RNAs to sequester themselves in droplet-like compartments within the cell—effectively shutting down production of the proteins the RNAs encode.

"Scientists have known that droplets of sequestered RNAs can form in cells, for example during conditions of cellular stress. The droplet-like compartments formed under these conditions are called "stress granules." The discovery by Dr. Jaffrey and colleagues shows that m6A marks are one trigger that causes mRNAs to be placed into stress granules."

Comment: Of course the genome will have built-in protections. This degree of complexity requires design.