JUN 10, 2019 7:24 AM PDT

CRISPR 2.0: Using Transposons to Improve and Expand CRISPR Application

WRITTEN BY: Amanda Mikyska

Source: Science showing cas12k binging and gene insertion. 

CRISPR-cas9, commonly referred to simply as CRISPR, is a bacterial immune system that was first used as a gene-editing tool in 2012.  Since the first application to gene-editing, CRISPR has made gene-editing faster, easy to design, and easy to execute.  Resistance to CRISPR in human gene therapy is due to the risk of "off-target" effects.  Though the risk is small, and debated, off-target effects can be devastating and irreversible.  Additionally, CRISPR is very useful in deleting or inactivating genes, but scientists have found it very difficult to use it to insert or repair genes.  While studies that demonstrate CRISPR's application continues, some scientists like Feng Zhang at the Broad Institute, have focused on making CRISPR more precise.  

A team of scientists from the Broad Institute and the National Institutes of Health have engineered a CRISPR system which makes use of transposon activity to increase the specificity of gene-insertion and decrease the risk of off-target effects.  The new mechanism is a sandwich with a shCAST loci in the middle, a transposase gene at one end, and a  cas12k protein at the other.  The shCAST locus is a type of CRISPR system which was isolated from a cyanobacterium.  The job of shCAST is to integrate DNA at a specific site determined by the transposase.  The transposase gene is called Tn-7, and like all transposons (or, "jumping genes") it can move around the genome.  Tn-7 copies and pastes the gene it is attached to it in the engineered sandwich.  Tn-7 precisely identifies the insertion site 60-66bp downstream of the protospacer sequence in shCAST.  Lastly, cas12k is a protein sequence with the function of finding the protospacer sequence for Tn-7.  All together, cas12k finds the protosequence, Tn-7 moves 60-66bp downstream of that sequence and then makes copies of the gene intended for insertion.  Finally, shCAST inserts copies of the gene that Tn-7 synthesized.  

Source: Harvard showing a basic schematic of transposons. 

This new gene-editing technology has a successful insertion rate of 80% but has only been tested in bacterial organisms.  Extensive experimentation in eukaryotic cells is needed before the technology can be considered for medical application.  Still, finding possible solutions to the risks of CRISPR, only seven years after the groundbreaking technology was first used as a gene-editing tool, is exciting.

 

Sources: Discover Magazine, Science, GenomeWeb, NewScientist, Harvard

About the Author
  • Amanda graduated from the University of Massachusetts Boston with a degree in Biology. After working in research on creating biochemicals from genetically engineered yeast, she started freelance science writing while traveling the world. Now, Amanda is a Lab Manager and Research Assistant at the the University of Central Florida, studying the molecular phylogeny of parasitic wasps. She writes about the latest research in Neuroscience, Genetics & Genomics, and Immunology. Interested in working on solutions for food/water security, sustainable fuel, and sustainable farming. Amanda is an avid skier, podcast listener, and has run two triathlons.
You May Also Like
MAR 02, 2020
Genetics & Genomics
MAR 02, 2020
DNA Replication Discovery May Lead to New Cancer Treatments
Researchers have learned more about DNA replication during cell division, and their insights may help create new types o ...
MAR 03, 2020
Cell & Molecular Biology
MAR 03, 2020
New CRISPR-HOT Technique Can Color Cells and Genes
Since the CRISPR/Cas9 editing tool was developed several years ago, many scientists have modified and improved it for di ...
MAR 17, 2020
Genetics & Genomics
MAR 17, 2020
Targeting RNA With CRISPR
Researchers screened thousands of target molecules to find the most effective targets, and have made their data openly a ...
MAR 29, 2020
Genetics & Genomics
MAR 29, 2020
Biomarkers That Predict Crohn's Disease Are Identified
A series of studies published in Gastroenterology has outlined new approaches in predicting IBD.
APR 13, 2020
Microbiology
APR 13, 2020
Even Bacteria Align With the Daily Cycle of Day and Night
The majority of living organisms on Earth have adapted in some way to the daily cycle of night and day.
APR 14, 2020
Genetics & Genomics
APR 14, 2020
How Deer Antlers Can Teach Us About Cancer Treatment
Deer antlers grow faster than cancerous tumors.
Loading Comments...