Recording Memories in DNA?

[DrmDoc]

According to this MSN article, MIT researchers have found a way to edit a CRISPR gene to record histories in human DNA. Though not necessarily for storing our medical history, the article suggests this technique could have uses in cancer related studies. The article also has a link to the MIT announcement. Enjoy!

Edited August 22, 2016 by DrmDoc

[jimmydasaint]

This is so damn clever. If I read it correctly, CRISPR is a tool to edit DNA in a specific way. CRISPR has two parts to it: a cutting tool called Cas9 and a guide RNA. The RNA guide strand which is complementay to specific DNA binds to it. As it does so, the Cas9 bit of CRISPR cuts the DNA. Usual gene editing can add or delete a piece of DNA if required. This is a mutation created specifically in a specific part of the DNA.

 

In this case, the toolkit is used so that the very DNA of the cell which made the guide RNA is cut by CRISPR but only if a certain molecule is present, e.g. like a molecule present during inflammation. As the DNA is cut by the CRISPR, a deletion is made (frameshift?) which then changes the sequence of the guide RNA. The CRISPR then travels back to the DNA with a changed sequence and cuts it out. the longer the stimulus/inflammation etc... molecule is present, the more mutations that accumulate in the DNA that codes for the guide RNA.

 

Others can correct my interpretation, but, if what I have written is correct, this is the most exciting thing I have read in years. Great find DrmDoc!

 

(Caveat - if I have ballsed up the explanation, please correct me)

 

 

When using CRISPR to edit genes, researchers create RNA guide strands that match a target sequence in the host organism’s genome. To encode memories, the MIT team took a different approach: They designed guide strands that recognize the DNA that encodes the very same guide strand, creating what they call “self-targeting guide RNA.”

 

Led by this self-targeting guide RNA strand, Cas9 cuts the DNA encoding the guide strand, generating a mutation that becomes a permanent record of the event. That DNA sequence, once mutated, generates a new guide RNA strand that directs Cas9 to the newly mutated DNA, allowing further mutations to accumulate as long as Cas9 is active or the self-targeting guide RNA is expressed.

By using sensors for specific biological events to regulate Cas9 or self-targeting guide RNA activity, this system enables progressive mutations that accumulate as a function of those biological inputs, thus providing genomically encoded memory.

For example, the researchers engineered a gene circuit that only expresses Cas9 in the presence of a target molecule, such as TNF-alpha, which is produced by immune cells during inflammation. Whenever TNF- alpha is present, Cas9 cuts the DNA encoding the guide sequence, generating mutations. The longer the exposure to TNF-alpha or the greater the TNF-alpha concentration, the more mutations accumulate in the DNA sequence.

By sequencing the DNA later on, researchers can determine how much exposure there was.

http://news.mit.edu/2016/recording-analog-memories-human-cells-0818?ncid=txtlnkusaolp00000618

 

Images show DNA being made into complementary RNA and then an image on how CRISPR works.

 

Edited August 22, 2016 by jimmydasaint