CRISPR/Cas genome engineering system generates valuable conditional mouse models

August 29, 2013

CAMBRIDGE, Mass. (August 29, 2013) - Whitehead Institute researchers have used the gene regulation system CRISPR/Cas to engineer mouse genomes containing reporter and conditional alleles in one step. Animals containing such sophisticated engineered alleles can now be made in a matter of weeks rather than years and could be used to model diseases and study gene function.

"We've used CRISPR/Cas to mutate genes before, but the nature of the targeted mutations has been unpredictable," says Whitehead Founding Member Rudolf Jaenisch. "Now we can make specific deletions defined by two cuts. We can use this to make conditional mice in one step, and we can easily and very efficiently insert pieces of DNA up to three thousand base pairs It used to be much more work to make such mice."

The CRISPR/Cas (for "clustered regularly interspaced short palindromic repeat/CRISPR-associated) system is based on an immune defense against viral invaders in bacteria and archaea. Scientists recently have adapted that defense to alter the genomes of mouse and human cells quickly and efficiently. Until now, however, researchers had yet to use CRISPR/Cas to create one of the most useful tools for genetic research: the conditional mutant mouse.

A conditional mutant mouse's genome contains a gene or collection of genes that can be turned on or off using a particular signal. By turning the genes on or off, scientists can tease apart the role of certain genes in biological functions and diseases.

Previously, scientists created such model organisms using a complex and time-consuming process that requires using embryonic stem cells (ESCs). Unfortunately, scientists have only been able to efficiently manipulate the ESCs of mice and rats, a restriction that has hobbled this type of research.

Using CRISPR/Cas, Jaenisch and his lab have created mice with conditional alleles, as well as mice that carry multiple tagged genes that report whether these genes are being expressed. Their work is described in the September 12 issue of the journal Cell.

The researchers' experiments also allay concerns regarding CRISPR/Cas's off-target activity.

"Recent studies in human cancer cell lines raised some concerns on the specificity of CRISPR/Cas," says Chikdu Shivalila, a co-author of the Cell paper and a graduate student in the Jaenisch lab, "Our study shows that the non-specific DNA cleavages could happen, but they are rare and predictable."

The Jaenisch lab's latest work opens up a number of avenues for future research.

"The methods we described in this work will greatly accelerate the speed of generating gene modified animals," says Hui Yang, a postdoctoral researcher in the Jaenisch lab and co-author. "I'd like to use CRISPR/Cas to establish sophisticate disease models using this method."

Because CRISPR/Cas does not rely on ESCs, it can be used to genetically modify any animal, including livestock.

"We haven't tried it yet, but I'd like to adapt the CRISPR/Cas system for genome engineering in large animals, such as primate for disease modeling, or cattle for agricultural purposes," says Haoyi Wang, a co-author and a postdoctoral researcher in the Jaenisch lab. "If so, this method could be very important economically, too."
This work is supported the Croucher Foundation and National Institutes of Health (NIH) grants HD 045022 and R37CA08419.

Written by Nicole Giese Rura

Rudolf Jaenisch's primary affiliation is with Whitehead Institute for Biomedical Research, where his laboratory is located and all his research is conducted. He is also a professor of biology at Massachusetts Institute of Technology.

Full Citation:

"One-step generation of mice carrying reporter and conditional alleles by CRISPR/Cas mediated genome engineering"

Cell, September 12, 2013.

Hui Yang (1,4), Haoyi Wang (1,4), Chikdu S. Shivalila (1,2,4), Albert W. Cheng (1,3), Linyu Shi (1), Rudolf Jaenisch (1,3).

1. Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, USA
2. Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
3. Computational and Systems Biology Program, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
4. These authors contributed equally to this work.

Whitehead Institute for Biomedical Research

Related Genome Articles from Brightsurf:

Genome evolution goes digital
Dr. Alan Herbert from InsideOutBio describes ground-breaking research in a paper published online by Royal Society Open Science.

Breakthrough in genome visualization
Kadir Dede and Dr. Enno Ohlebusch at Ulm University in Germany have devised a method for constructing pan-genome subgraphs at different granularities without having to wait hours and days on end for the software to process the entire genome.

Sturgeon genome sequenced
Sturgeons lived on earth already 300 million years ago and yet their external appearance seems to have undergone very little change.

A sea monster's genome
The giant squid is an elusive giant, but its secrets are about to be revealed.

Deciphering the walnut genome
New research could provide a major boost to the state's growing $1.6 billion walnut industry by making it easier to breed walnut trees better equipped to combat the soil-borne pathogens that now plague many of California's 4,800 growers.

Illuminating the genome
Development of a new molecular visualisation method, RNA-guided endonuclease -- in situ labelling (RGEN-ISL) for the CRISPR/Cas9-mediated labelling of genomic sequences in nuclei and chromosomes.

A genome under influence
References form the basis of our comprehension of the world: they enable us to measure the height of our children or the efficiency of a drug.

How a virus destabilizes the genome
New insights into how Kaposi's sarcoma-associated herpesvirus (KSHV) induces genome instability and promotes cell proliferation could lead to the development of novel antiviral therapies for KSHV-associated cancers, according to a study published Sept.

Better genome editing
Reich Group researchers develop a more efficient and precise method of in-cell genome editing.

Unlocking the genome
A team led by Prof. Stein Aerts (VIB-KU Leuven) uncovers how access to relevant DNA regions is orchestrated in epithelial cells.

Read More: Genome News and Genome Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to