A new study published in Nature scientists finds that RNA, considered the DNA template for protein translation, often appears with an extra letter -- and this letter is the regulatory key for control of gene expression.

"Epigenetics, the regulation of gene expression beyond the primary information encoded by DNA, was thought until recently to be mediated by modifications of proteins and DNA," said the author.

The number of modified nucleotides (letters) in RNA is 10 times larger than that of the letters found in DNA. But what accounts for the evolutionary drive for a large RNA alphabet? RNA molecules have a wide variety of functions, including storage of genetic information as well as catalytic, structural, and regulatory activities. This is in contrast to the important but one-dimensional function of DNA in encoding genetic information.

"The 140 or so different modifications that decorate RNA increase significantly the vocabulary of RNA and enable the various types of RNA, including mRNA, rRNA, tRNA, siRNA, miRNA and, lncRNA, to implement their versatile activities," said the author.

Researchers began exploring the landscape of chemical modifications of messenger RNA (mRNA) four years ago through a specific modification: the addition of a methyl group in position 6 of Adenosine (m6A) in mRNA. The research team then showed that this modification is specific to unique regions of the mRNA molecules and that the modification can be "read" by specific proteins. They also showed that this modification is dynamic and responds to environmental stimuli.

Another group of researchers unraveled a new dynamic modification of mRNA -- the methylation of position 1 of Adenosine (m1A). Importantly, this modification was shown to be localized in a telltale position near the start of protein translation and linked to increased protein synthesis.

The research groups are currently studying the cellular processes involved in "writing" and "erasing" m1A, as well as the biochemical pathways regulated by this new RNA modification. In the future, they plan to explore the role of m1A methylation in embryonic development and its involvement in cancer and neurodegenerative disorders.

https://www.aftau.org/weblog-medicine--health?=&storyid4704=2254&ncs4704=3