Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UCLA researchers identify key enzyme linked to childhood blindness

12.08.2005


Findings could lead to gene therapy cure



In findings that could lead to curing some forms of congenital blindness through gene therapy, researchers at UCLA have discovered that RPE65, a gene missing in infants born with the blinding disease Leber congenital amaurosis, is also a key enzyme in the visual cycle. The identity of this enzyme has long been a mystery to scientists.
The study, "Rpe65 is the Retinoid Isomerase in Bovine Retinal Pigment Epithelium," is published in the Aug. 12 issue of Cell magazine.

"We were amazed when we discovered the function for Rpe65 -- and that Rpe65 is the retinoid isomerase. It is a protein that all of us had known about for years," said Dr. Gabriel Travis, professor of ophthalmology and biological chemistry at UCLA’s Jules Stein Eye Institute and one of the researchers. "It’s like searching the world for a treasure, then discovering it in your own back yard."



Leber congenital amaurosis is an inherited disease that is believed to cause up to 20 percent of all cases of childhood blindness. It is caused by mutations in several different genes including RPE65. An important characteristic of this disease is that the light sensitive rod and cone cells remain intact in the retinas of Leber patients for a long time.

"This suggests that replacement of RPE65 by gene therapy should correct the blindness in these children, as was observed in mice and dogs with RPE65 mutations," Travis said. "This is a major breakthrough in understanding the visual cycle. It has ramifications for several inherited blinding diseases caused by mutations in visual cycle genes."

The newly identified isomerase enzyme plays a crucial role in the regeneration of rhodopsin visual pigment in the retina after light exposure. Rhodopsin contains a light absorbing molecule called 11 cis retinaldehyde, related to vitamin A, which is converted upon light absorption to all trans retinaldehyde in a process called photo bleaching. This conversion is the first step in visual perception.

Photo bleaching leaves the rhodopsin insensitive to light until the all trans retinaldehyde is converted, or "isomerized," back into 11 cis retinaldehyde, which completes the visual cycle. Scientists have for two decades been attempting to identify the retinoid isomerase enzyme that catalyzes this regeneration of 11 cis retinaldehyde. Scientists have also been stumped by the function of the Rpe65 protein

Working with Travis at the Jules Stein Eye Institute, Dr. Minghao Jin, visiting assistant researcher in ophthalmology, performed an expression screen in cultured human cells, looking for a gene that caused these cells to convert vitamin A into 11 cis retinol.

The researchers are now studying the effects on retinoid isomerase activity of specific disease causing mutations in the RPE65 gene, which should provide more data on the cause of Leber congenital amaurosis and on how the Rpe65 protein works. The researchers are also examining the function of other proteins that work closely with Rpe65. Mutations in the genes for these interacting proteins are linked to other forms of human blindness.

"These results settle the long standing mystery about the identity of the retinoid isomerase," Travis said. "Scientists have been searching for this enzyme for almost 20 years. Our results also explain why finding this enzyme has been so difficult, until now."

Other researchers on this project besides Travis and Jin are Hui Sun, assistant professor of physiology at UCLA, and Songhua Li and Walid Moghrabi, staff research associates at the Jules Stein Eye Institute.

Enrique Rivero | EurekAlert!
Further information:
http://www.mednet.ucla.edu

More articles from Life Sciences:

nachricht Fine organic particles in the atmosphere are more often solid glass beads than liquid oil droplets
21.04.2017 | Max-Planck-Institut für Chemie

nachricht Study overturns seminal research about the developing nervous system
21.04.2017 | University of California - Los Angeles Health Sciences

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

Im Focus: Quantum-physical Model System

Computer-assisted methods aid Heidelberg physicists in reproducing experiment with ultracold atoms

Two researchers at Heidelberg University have developed a model system that enables a better understanding of the processes in a quantum-physical experiment...

Im Focus: Glacier bacteria’s contribution to carbon cycling

Glaciers might seem rather inhospitable environments. However, they are home to a diverse and vibrant microbial community. It’s becoming increasingly clear that they play a bigger role in the carbon cycle than previously thought.

A new study, now published in the journal Nature Geoscience, shows how microbial communities in melting glaciers contribute to the Earth’s carbon cycle, a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

New quantum liquid crystals may play role in future of computers

21.04.2017 | Physics and Astronomy

A promising target for kidney fibrosis

21.04.2017 | Health and Medicine

Light rays from a supernova bent by the curvature of space-time around a galaxy

21.04.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>