Cell History Recording Through CRISPR

Artist's representation of the CRISPR-Cas9 system (Image source: phys.org)

By: Renald James Legaspi (Polinton)

Changes in the genetic material brought about by infections and environmental stresses, in most cases, leave molecular traces in the cell. By practice, researchers could accurately trace these changes by measuring the gene activity through the transcript or mRNA equipped with the molecular traces. However, due to the high instability of mRNA, it tremendously decreases the efficacy for tracing cell history. Thus, a novel method using CRISPR-Cas System provides a more promising approach for this cause.

Randell Platt, a researcher from the Department of Biosystems Science and Engineering, and his colleagues developed a permanent molecular recording method by writing transcriptional events into DNA that is re-accessed through sequencing.

The group employed the use of CRISPR-Cas System known to offer prokaryotic adaptive immunity. Naturally, this system records the genetic information of mobile genetic elements infecting a certain organism through the process known as CRISPR spacer integration.

Spacers or the pathogen-acquired sequences are separated by direct repeats and are closely associated with the genes required in the mechanism of the CRISPR System. These associate genes are generally called cas genes.

Platt's method made use of E.coli wherein the group infused one of the cas genes with a reverse transcription allowing DNA synthesis from an RNA transcript. These acquired DNA are stored in the CRISPR array, which is a process similar to a recording device or a computer memory storage.

More importantly, according to the group, this process could be repeated multiple times using a single CRISPR System allowing the possibility of several spacers in an array.

Using the order-logic, a certain DNA sequence could be traced upon and its order of entry compared to other sequences by counting the direct repeats naturally flanking between spacers.

"Researchers have been working on creating forms of synthetic cellular memory for a long time, but we are the first to develop one that can record information about the expression of each gene in a cell over time."

As said by Randall, this technique not only provides with a recording device of a cell's history but allows the creation of ordered and logical inferences, for it uses a system that is naturally efficient and stable in nature.

For these, the team spent two years of labor but is dedicated to spend more years for the endeavor of this revolutionary method.

Reference:

ETH Zurich. "Recording device for cell history." ScienceDaily. ScienceDaily, 3 October 2018. <www.sciencedaily.com/releases/2018/10/181003134441.htm>.