Researchers at Duke University have developed a method for activating genes into a pattern or specific location by using light for the purpose of providing stimulation.
Researchers demonstrate their new technique to control genes by shining light through a “Duke D” stencil to turn on fluorescent genes in cells.
“This technology should allow a scientist to pick any gene on any chromosome and turn it on or off with light, which has the potential to transform what can be done with genetic engineering” said Lauren Polstein, a Duke PhD student and lead author on the work. “The advantage of doing this with light is we can quickly and easily control when the gene gets turned on or off and the level to which it is activated by varying the light's intensity. We can also target where the gene gets turned on by shining the light in specific patterns, for example by passing the light through a stencil.”
The technique targets specific genes using a new genetic engineering system called CRISPR/Cas9. The system was originally discovered as that which bacteria used to identify viral invaders and slice up their DNA; following its discovery, the system was co-opted by researchers to target specific genetic sequences.
As progress was made, the researchers thought it advantageous to make the system light-activated, thereby providing greater control.
A good example of how it’s used can be found with plants. In most cases, two proteins in a plant lock together when exposed to light. This allows the plant to sense the length of day which, in turn, determines biological functions like flowering. When the team applied the CRISPR/Cas9 system to one of these proteins and gene-activating proteins to the other, they were able to turn several different genes on or off simply by shining a blue light on the cells.
“The light-sensitive interacting proteins exist independently in plants,” explained Charles Gersbach, who is an assistant professor of biomedical engineering at Duke University and the leader of this study. “What we've done is attached the CRISPR and the activator to each of them. This builds on similar systems developed by us and others, but because we're now using CRISPR to target particular genes, it's easier, faster and cheaper than other technologies.”
There are several applications to which this new form of genetic engineering can be applied. For one, researchers could control the level of a gene’s activity from its natural position in the chromosomal DNA with greater precision than ever before. This would give them the ability to more accurately determine the gene’s role.
The light system could also provide more control over how stem cell cultures distinguish themselves into different types of tissues. Given the system’s ability to create gene expressions of various patterns, the Duke system can be used in tissue engineering.
“One of the limitations of tissue engineering right now is that typical methods make a chunk of bone, cartilage or muscle, but that's not what tissues look like naturally,” said Gersbach. “There are several cell types mixed together, gradients of tissues between interfaces, and blood vessels and neurons that penetrate through them. We want to spatially control where different tissues get made in a cell population, and that way create multi-tissue constructs that potentially better represent normal physiology.”
Gersbach went on to hypothesize a far more futuristic idea of how his group’s light-induced genetic engineering system could also be applied.
“It's possible to illuminate cells through the skin and control what they're doing, like growing blood vessels or regenerating tissues,” said Gersbach. “Far, far down the road, you could envision the type of device you'd see on Star Trek where you wave a flashlight over a wound and it heals. Obviously that's not currently possible, but this type of technology that creates much better control over biological systems could move us in that direction.”
Gersbach’s study was published on February 9 in Nature Chemical Biology.
http://www.nature.com/nchembio/journal/vaop/ncurrent/full/nchembio.1753.html
Via Duke University
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