JUN 10, 2019 07:24 AM PDT

CRISPR 2.0: Using Transposons to Improve and Expand CRISPR Application

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
  • Intern research scientist genetically engineering yeast to making a renewable fuel. Interested in food/water security, sustainable fuel, and sustainable farming.
You May Also Like
NOV 13, 2019
Genetics & Genomics
NOV 13, 2019
Detecting DNA - Without Amplification
As genetic technologies rapidly advance, totally new approaches are now possible. One innovation is the CRISPR-Chip....
NOV 13, 2019
Drug Discovery & Development
NOV 13, 2019
AI Exponentially Accelerates Drug Development
Research and development for new drugs is both an expensive and lengthy process, often lasting years, if not decades. With the development of artificial in...
NOV 13, 2019
Genetics & Genomics
NOV 13, 2019
A More Precise Version of CRISPR/Cas9 is Created
A more accurate version of Cas9 has been created, reducing the number of off-target effects. It may be better suited for use in gene therapy....
NOV 13, 2019
Genetics & Genomics
NOV 13, 2019
Risk Factors for Gout Revealed by Genome-Wide Association Study
Gout is a common type of arthritis, and causes severe and sudden pain, redness and swelling in the joints....
NOV 13, 2019
Genetics & Genomics
NOV 13, 2019
Genetic Variations Connected to Severe Forms of Multiple Sclerosis
Scientists are learning more about the genetic factors underlying MS, which is a highly variable disease....
NOV 13, 2019
Drug Discovery & Development
NOV 13, 2019
Therapeutic Targets Inflammation Associated with Genetic Heart Disease
Often times when young athletes collapse during the game it is due to sudden cardiac death as a result of the inherited arrhythmogenic cardiomyopathy (ACM)...
Loading Comments...