Most people I talk to haven’t taken a biology class since high school – but try to reach back into the shadowy depths of your inner-high school student and remember the “Central Dogma” of molecular biology - this dogma is what biology is built on, this is geneticist’s and molecular biologist’s bread and butter:
DNA encodes bases (ATCG’s) that will be transcribed into messenger RNA (mRNA), this mRNA will be the template that will be translated into proteins.
Today a paper in Science challenges this theory – and who better to challenge the stable ground that biologists walk on than RNA. Sticking to the high school theme, RNA is molecular biology’s “bad boy”, the sexy boundary-pushing bad boy that breaks all the rules in all of the right ways.
Mingyao Li et al. have found that RNA has challenged the Central Dogma, showing that in human cells many proteins do not match their underlying DNA sequences. They found in the 27 human subjects looked at, that over 28,000 events occurred where the RNA sequences did not match that of the DNA. Using mass spectrometry to identify the proteins translated from the RNA, they found that the proteins do not correspond to the DNA sequences in which they originated.
There have been known reasons why RNA does not match DNA and these have been shown to be very rare and could not be seen widespread in a human cell population. Here they have found this RNA editing occurs much more frequently than anyone had ever thought.
To put things in perspective, these RNA edits may be a source of human genetic diversity that had previously been unknown – and this diversity may explain why different people are more susceptible to different diseases.
Li M, Wang IX, Li Y, Bruzel A, Richards AL, Toung JM, & Cheung VG (2011). Widespread RNA and DNA Sequence Differences in the Human Transcriptome. Science (New York, N.Y.) PMID: 21596952