In the July 29 issue of Science, the Weill Cornell investigators report how they developed an RNA mimic of green fluorescent protein (GFP) -- which they dubbed Spinach -- and describe how it will help unlock the secrets of the complex ways that RNA sustains human life as well as contributes to disease.
"These fluorescent RNAs offer us a tool that will be critical for understanding the diverse roles that RNA plays in human biology," says the study's senior author, Dr. Samie Jaffrey, an associate professor of pharmacology at Weill Cornell Medical College.
In recent years, the many roles played by RNA have become clearer. "Scientists used to think that RNA's function was limited to making proteins and that these proteins alone dictated everything that happened in cells," he says. "But now we are understanding that cells contain many different forms of RNA -- and some RNAs influence cell signaling and gene expression without ever being used for synthesizing proteins."
The list of known types of RNA has grown rapidly over the past several years -- from messenger RNA that codes for proteins, to diverse "non-coding" RNAs that affect translation and gene expression, and in some cases bind to proteins and regulate their function -- yet little is known about how these RNAs work, the researchers say.
The study's first author, Dr. Jeremy Paige, who conducted the research as a graduate student in pharmacology at Weill Cornell Medical College, adds that the new technology may provide insights into the development of common disorders. "More and more diseases are being linked to misregulation of RNA, but without being able to see the RNA, we can't understand how these processes lead to disease.
"We hope our RNA mimics of GFP open up the road to discovery," he says.
The RNAs developed by the Jaffrey group function like GFP, a natural protein expressed in jellyfish that exhibits a green fluorescence. GFP has enabled scientists to watch how proteins move in cells, providing powerful new insights into their roles in cell function. The DNA that encodes GFP is placed next to a gene that encodes for a protein, resulting in the expression of a protein fused to GFP, which can be observed by specialized forms of microscopy.
To make an RNA that functions like GFP, the Weill Cornell investigators took advantage of the ability of RNA to fold into complex three-dimensional shapes. Their goal was to create two new entities: a synthetic RNA sequence that would adopt a specific shape, and a small molecule that would bind to the new RNA and begin to fluoresce. "These were two huge challenges," says Dr. Jaffrey. "One challenge was to come up with an RNA sequence that could 'switch on' a small molecule. The other big hurdle was to find a small molecule that would fluoresce only when we wanted it to and would not be toxic to cells."
They tried a number of molecules, most of which stuck to oily lipids in the cell membrane and started fluorescing, or they would kill the cell. Finally, the team realized that GFP itself had a molecule, a fluorophore, within it that switched its light on when it was bound in a certain way within the protein. They created chemical molecules based on the shape of this fluorophore and then developed an artificial RNA sequence, or "aptamer," that held the fluorophore in exactly the same way that GFP held its fluorophore. They named this RNA "Spinach" for its bright green fluorescence.
The researchers went even further. They also developed several other RNA-fluorophore pairs, in addition to Spinach, that each emit a different fluorescent color, just as GFP has been evolved to exhibit a palette of colors that helps researchers track many proteins at once. Whereas GFP derivatives are often named after fruits, the Weill Cornell researchers named their RNA mimics of GFP after vegetables -- Spinach, Carrot and Radish.
The Weill Cornell investigators have already begun to use Spinach to track non-coding RNAs in cells. "Our laboratory has been very interested understanding why defects in RNA trafficking and translocation lead to developmental disorders in children, such as mental retardation," says Dr. Jaffrey. Using Spinach, they were able to watch as a non-coding RNA, fluorescing green, rapidly clusters in response to cellular stress. "We expect that Spinach will provide new insights into RNA trafficking in cells, and how this is affected in medical disorders," he says.
"There is still a lot of mystery surrounding RNA in biology. Fluorescent labeling and imaging has proved to be a powerful tool for scientists in the past, and we are hoping that Spinach too will be a tool that helps accelerate scientific discovery," says Dr. Paige.
Dr. Karen Wu of the Department of Pharmacology is a co-author on the study.
The work was supported by the McKnight Neuroscience Technology Innovation Award and the National Institutes of Neurological Disorders and Stroke.
Weill Cornell Medical College has filed a patent application on the technology.Weill Cornell Medical College
Andrew Klein | Newswise Science News
Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory
Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine