Novel RNA Switch Dramatically Boosts Expression

Researchers at Northwestern University say they have developed a novel technique that dramatically boosts gene expression. According to Julius Lucks, Ph.D., an associate professor of chemical and biological engineering in the university’s McCormick School of Engineering, if scientists could precisely regulate gene expression, they could turn off the genes responsible for illness and disease and turn on those that enhance health and the immune system.

“All we did was make an RNA switch that turns a gene on,” he reports. “But what really makes it awesome is that it’s really, really, really good.”

Dr. Lucks and his team published their study (“Computational Design of Small Transcription Activating RNAs for Versatile and Dynamic Gene Regulation”) in Nature Communications.

“A longstanding goal of synthetic biology has been the programmable control of cellular functions. Central to this is the creation of versatile regulatory toolsets that allow for programmable control of gene expression. Of the many regulatory molecules available, RNA regulators offer the intriguing possibility of de novo design—allowing for the bottom-up molecular-level design of genetic control systems,” write the investigators.

“Here we present a computational design approach for the creation of a bacterial regulator called Small Transcription Activating RNAs (STARs) and create a library of high-performing and orthogonal STARs that achieve up to ~ 9000-fold gene activation. We demonstrate the versatility of these STARs—from acting synergistically with existing constitutive and inducible regulators, to reprogramming cellular phenotypes and controlling multigene metabolic pathway expression. Finally, we combine these new STARs with themselves and CRISPRi transcriptional repressors to deliver new types of RNA-based genetic circuitry that allow for sophisticated and temporal control of gene expression.”

Dr. Lucks likens STARs to a light switch.

“For anything to happen in biology, the ‘light’ has to be turned on,” he says. “We’re always interested in turning things on, so we found a way to engineer some really good light switches.”

Continuing the analogy, he explains that the RNA switches found in nature are unable to turn the “lights” fully on or off. Oftentimes the room is consistently dim instead of completely dark or brilliantly light. But researchers want to have a tighter control of the system. Dr. Lucks’ STAR can turn on the light, or activate a gene, 9000 times brighter than without the STAR present, providing the completely dark or light room that researchers have lacked.

“If you study a system to explore what a gene does, you want to know what it does when it’s completely on or off,” he says. “Not when the gene is there or halfway there. That’s much harder to disentangle,” adding that’s particularly true for diagnostic applications, which he plans to pursue next with his new tool. Because RNA excels at detecting other strands of RNA, STARs could be useful in diagnosing RNA viruses. To do this, Dr. Lucks’ switch could be engineered to turn on in the presence of one of these viruses.