Nanobody can help CRISPR switch genes on and off

The genetic tool CRISPR is compared to molecular scissors because it has the ability to cut out and replace genetic code within DNA. But CRISPR has the ability to make it useful outside of genetic repair. “CRISPR can accurately detect specific genes,” says Lacramioara Bintu, an assistant professor of bioengineering at Stanford. “What we did was attach CRISPR to nano-bodies to help it perform specific actions when it reached the right place on DNA.”

Her laboratory recently used this combination technique to convert CRISPR from a no-cut scissors to a nanoscale control agent that can turn specific genes on and off, such as a light switch, to start or stop the flow of some health-related proteins in a cell. .

“There are a lot of things you can not fix with scissors,” says Bintu. The romance technique her team describes in the journal Nature communication may enable researchers to explore new therapeutic applications in the field of epigenetics – this is the study of how genes behave in cells.

As Bintu explains, every cell in the human body has the same DNA – a complete complement of genes – but not every gene is turned on in every cell. Some cells carry certain genes that tell the cell to produce specific proteins. Others turned those off, but others turned on. Sometimes, as with genetic diseases, things go wrong with this switch. The new tool from the Bintu laboratory can correct the errors.

The new tool is more complicated than scissors because ordinary CRISPR cannot turn genes on and off in a controlled way without breaking the DNA. To make changes without harming the DNA, CRISPR needs the help of other large, complex proteins known as ‘effectors’. With the new combination tool, CRISPR finds the right gene, and the effector can turn the switch.

“But these effector molecules are usually too large to be easily delivered into a cell for therapeutic use,” says Ph.D. student Mike Van, first author of the paper. Further complications are that multiple effectors are usually used in combination to effectively regulate specific cell behaviors, making the combination of CRISPR effects even greater, thus more difficult to produce and deliver.

To circumvent this roadblock, Bintu’s team turned to smaller proteins known as nanobody. Nano-bodies do not act as institutions for the effectors. Instead, they act as small hooks that trap the necessary effects already swimming in the cell. Choose the right nanobody and it recruits the right effector for switching.

The new technique can be used to correct epigenetic defects without combining CRISPR with major effects. “The cells already have these proteins,” Bintu explains. “We thought: why are we attaching it again? Let’s use nanobody to do this.”

At this stage, the technique is in the proof-of-concept stage. The next step is for the team to sort out millions of potential nano-bodies and start figuring out how they can be attached to CRISPR to target specific epigenetic breakdown points.

“We have just devised a method to test hundreds of thousands at a time,” says Bintu, who hopes to further develop the technique in future experiments.

Provided by Stanford University School of Engineering