Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Ray of hope for human Usher syndrome patients

Biologists at Mainz University achieve repair and read-through of stop mutations responsible for the disease

After years of basic research, scientists at Johannes Gutenberg University Mainz (JGU) are increasingly able to understand the mechanisms underlying the human Usher syndrome and are coming ever closer to finding a successful treatment approach.

Fluorescence microscope image of cells with a nonsense mutation in the Usher syndrome 1C gene (USH1C/harmonin). In the presence of the designer aminoglycoside NB54, there is read-through of the USH1C mutation. The treated cells produce the healthy harmonin protein (green). Source: Kerstin Nagel-Wolfrum, Institute of Zoology, JGU

The scientists in the Usher research group of Professor Dr. Uwe Wolfrum are evaluating two different strategies. These involve either the repair of mutated genes or the deactivation of the genetic defects using agents. Based on results obtained to date, both options seem promising. Usher syndrome is a congenital disorder that causes the loss of both hearing and vision.

Usher syndrome is the most common form of congenital deaf-blindness in humans, occurring in 1 in 6,000 of the population. Those suffering from the disease are drastically handicapped in everyday life as they lose the use of the two most important sensory organs, i.e., their ears and eyes. In the most severe cases, patients are born deaf and begin to suffer from vision impairment in the form of retinal degeneration in puberty that result in complete blindness.

While it is possible to compensate for the loss of hearing with hearing aids and cochlear implants, no therapy was previously available for the ophthalmic component of the disorder. Scientists at Mainz University are currently undertaking preclinical translational research in an attempt to find an answer to this problem.

The investigations undertaken by the team of Dr. Kerstin Nagel-Wolfrum focused on the nonsense mutation in the USH1C gene that had been identified as the cause of the most severe form of Usher syndrome in a German family. The nonsense mutation is a stop signal generated by the DNA that causes premature termination of synthesis of the protein harmonin, which is encoded by USH1C.

The research team published its latest findings with regard to gene repair as a possible treatment of Usher syndrome in the June edition of the opthalmologic journal Investigative Opthalmology & Visual Science. During her doctoral research, Dr. Nora Overlack managed to repair the USH1C gene with the help of molecular scissors' generated using the so-called zinc-finger nuclease technique. Using zinc-finger nuclease, the scientists first initiated a double sequence DNA cleavage at the site of the disease-generating mutation.

This surgical incision on the molecular level was then repaired by means of the cell's own repair mechanism in the form of homologous recombination and the introduction of a non-mutated USH1C DNA sequence. The mutated gene sequence was thus replaced with the non-mutated sequence. The efficacy of the zinc-finger nuclease technique with regard to genetic repair was demonstrated in a cell culture model at both the genome and the protein level.

The research team has also recently published the latest results of its pharmaco-genetic approach to the treatment of Usher syndrome patients with nonsense mutations in the journal EMBO Molecular Medicine. In this case, Dr. Tobias Goldman and the other team members compared various molecules that can induce read-through of the stop signal and thus provide for normal protein synthesis. In addition, they evaluated the retinal biocompatibility of the various molecules. The research focused on PTC124 (Ataluren®) and 'designer' aminoglycosides. These aminoglycosides are derived from clinically tested antibiotics and have been modified by Professor Dr. Timor Bassov of the Technicon in Haifa/Israel to improve their capacity to read-through the mutation and reduce their toxicity. The Mainz researchers had already been successful in using one of the first generation designer aminoglycosides to read-through the nonsense mutations in the USH1C gene.

They were now able to show that PTC124 (Ataluren®) and a second generation aminoglycoside (NB54) in particular would induce read-through of the stop signal in the mutated USH1C gene. This meant that protein synthesis continued, so that the active gene product was synthesized in the cell and organ cultures. Both active substances, PTC124 and NB54, generally enhanced read-through efficacy and exhibited improved tolerability in mouse and human retinal cultures in comparison with clinically employed antibiotics. The team also successfully documented read-through of the mutation in vivo a mouse model.

"Our gene-based treatment strategies, involving gene repair as well as read-through therapy, represent valuable and promising alternatives to viral gene addition and may actually be the only treatment option for the large and isoform-rich USH genes. We hope that these alternatives will make a significant contribution to the therapy of both Usher syndrome patients as well as others with severe genetic retinal pathologies and other genetic disorders," explains Dr. Kerstin Nagel-Wolfrum.

In addition to continuing its preclinical studies into the use of the active substances, the Mainz Usher research team plans to make its new Usher syndrome therapy available to patients as soon as possible.

The translational biomedical research into the treatment of Usher syndrome was carried out with the help of financial support from the EU-FP7 project SYSCILIA, the FAUN foundation, and the Foundation Fighting Blindness (FFB). The two involved doctoral candidates were research assistants and colleagues in the Research Training Group 1044: "Developmental and disease-induced modifications of the nervous system" supported by the German Research Foundation. The work of the Usher syndrome researchers is integrated in the Research Unit Translational Neurosciences (FTN) at Johannes Gutenberg University Mainz.

Nora Overlack, Tobias Goldmann, Uwe Wolfrum, Kerstin Nagel-Wolfrum
Gene repair of an Usher syndrome causing mutation by zinc-finger nuclease mediated homologous recombination
Investigative Ophthalmology & Visual Science, June 2012
Tobias Goldmann et al.
A comparative evaluation of NB30, NB54 and PTC124 in translational read-through efficacy for treatment of an USH1C nonsense mutation
EMBO Molecular Medicine, October 2012
Further information:
Dr. Kerstin Nagel-Wolfrum
Cell and Matrix Biology
Institute of Zoology
Johannes Gutenberg University Mainz (JGU)
D 55099 Mainz, GERMANY
phone +49 6131 39-20131 or 39-23934
fax +49 6131 39-23815

Petra Giegerich | idw
Further information:

More articles from Life Sciences:

nachricht Biologists unravel another mystery of what makes DNA go 'loopy'
16.03.2018 | Emory Health Sciences

nachricht Scientists map the portal to the cell's nucleus
16.03.2018 | Rockefeller University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

Im Focus: Radar for navigation support from autonomous flying drones

At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.

Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

International Virtual Reality Conference “IEEE VR 2018” comes to Reutlingen, Germany

08.03.2018 | Event News

Latest News

Wandering greenhouse gas

16.03.2018 | Earth Sciences

'Frequency combs' ID chemicals within the mid-infrared spectral region

16.03.2018 | Physics and Astronomy

Biologists unravel another mystery of what makes DNA go 'loopy'

16.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>