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 A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>