Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Technique May Identify Novel Disease Genes at a Faster Clip

14.11.2003


Researchers have used ultraviolet light to “weld” a key regulatory protein to its RNA targets, creating a new tool that can be used to identify novel proteins involved in a variety of human diseases.



Using this technique, the researchers have identified an array of RNA molecules regulated by the RNA-binding protein, Nova, which has been implicated in an autoimmune neurodegenerative disease. The researchers believe their technique may help in finding the RNA targets of other proteins involved in neurological diseases, including the most prevalent form of mental retardation, the Fragile X syndrome.

Robert B. Darnell, a Howard Hughes Medical Institute investigator at The Rockefeller University, led the research team that reported its findings in the November 14, 2003, issue of the journal Science.


Darnell and his colleagues have been investigating the function of Nova, an RNA-binding protein that regulates alternative splicing. In alternative splicing, messenger RNA, carrying the blueprint for a protein from the cell’s genes, is processed in such a way that it can produce a number of slightly different proteins. Apart from its role in alternative splicing, the Nova protein is of great interest, said Darnell, because it is targeted by the immune system in the neurodegenerative disease, paraneoplastic opsoclonus myoclonus ataxia, which causes progressive loss of motor control.

“Previous work in our laboratory had revealed how Nova bound to RNA, and we had identified a couple of specific target RNAs in the brain,” said Darnell. “These studies led us to discover that Nova was the first mammalian splicing factor that was restricted to a particular tissue. We then really wanted to know what is the full array of RNAs that Nova binds to and regulates in the brain?”

According to Darnell, Nova is just one of a rapidly growing list of RNA-binding proteins that are being implicated in human diseases. Thus, a technique that can help identify the multiple RNA targets regulated by an RNA-binding protein could potentially aid in understanding the cause of many human diseases.

To facilitate identification of the target proteins, the scientists adapted a technique that had been used in the test tube to identify the targets of RNA-binding proteins. This technique involved irradiating molecules with ultraviolet light, which caused a cross-linking reaction that chemically bonded the protein with its RNA target. The bond is so tight that the molecules could be isolated and identified together.

Darnell and his colleagues made some enhancements that resulted in the development of their “cross-linking and immunoprecipitation” (CLIP) technique. The researchers began by irradiating intact mouse brains with UV light, seeking to weld together RNA-binding proteins and their RNA targets in living tissue. Following a technically demanding purification and analytical procedure, the researchers were able to pinpoint some 340 Nova CLIP “tags” — telltale pieces of Nova-bound RNA that identified the RNA target molecule and revealed where the Nova protein bound to it. The researchers verified that the tags represented functional Nova RNA targets by comparing their splicing in wild-type mice with knockout mice lacking Nova.

The striking splicing changes in the knockout mice, said Darnell, constituted proof that Nova is the central regulator of splicing in a whole set of RNA molecules found in the brain. “We’re finding that Nova is an extremely important factor—maybe the factor—that is responsible for neuronal splicing for some targets,” he said.

Their studies turned up another important observation: Nova does not act randomly. “Looking at these targets as a group, they have a tremendous biological coherence to them,” said Darnell. “Almost seventy percent of them are RNAs that have something to do with the neuronal synapse.” Synapses are the junctions between neurons. One third of the Nova synaptic RNA targets encode proteins involved in inhibiting neuronal function. Regulating neuronal inhibition plays a key role in the balance controlling nervous system function normally as well as in neurologic disorders such as epilepsy, said Darnell.

“These findings suggest that Nova has evolved to regulate a set of RNAs that have a coordinate function,” he said. “So, if you turn Nova function up or down, you’ll coordinately regulate a group of RNAs en masse.”

The success of the CLIP method in identifying Nova targets, said Darnell, suggests that it will find broad use in discovering targets of other RNA-binding proteins, including those involved in such diseases as Fragile X mental retardation. “The study of the fragile-X-syndrome protein has been stuck, because knowing it’s an RNA-binding protein doesn’t really tell you what it’s doing,” said Darnell. “The problem has been to identify the set of RNAs that it regulates. We and others have made some progress using other techniques, but CLIP should help solve this problem.”

CLIP has also revealed that Nova may play a previously unsuspected role besides regulating alternate splicing. “We found quite a few instances of CLIP tags that are not near alternative splice sites, but are at the beginning or end of an RNA,” said Darnell. “This suggests that there may be some brand new biology going on that we didn’t suspect.” This new form of regulation might be occurring as RNA’s information is being translated into a protein by the cell’s protein-making machinery, Darnell said.

Jim Keeley | HHMI

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Taming 'wild' electrons in graphene

23.10.2017 | Physics and Astronomy

Mountain glaciers shrinking across the West

23.10.2017 | Earth Sciences

Scientists track ovarian cancers to site of origin: Fallopian tubes

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>