Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

As the Protein Folds: The Tail of the Gene Tells the Tale of Machado-Joseph Disease

01.04.2005


The repetition of three little "letters" within the gene that codes for the ataxin-3 protein is both the cause of and perhaps a solution to Machado-Joseph disease and an entire family of similar genetic disorders, according to researchers at the University of Pennsylvania. Their findings, which appear today in the journal Molecular Cell, present a potential therapeutic role for the ataxin-3 protein for MJD and related disorders such as Huntington’s disease.



Machado-Joseph disease is among the most common of the nine known polyglutamine repeat disorders, a family of diseases in which the genetic code for the amino acid polyglutamine CAG becomes excessively repeated within the gene, making the protein toxic. In these diseases, the expanded polyglutamine domain causes the errant protein to fold improperly, which causes a glut of misfolded protein to collect in tissues of the nervous system, much like what occurs in Alzheimer’s and Parkinson’s diseases.

"In origami, if you misfold the paper, you can just throw the paper into the recycling bin," said Nancy Bonini, a Penn professor of biology and Howard Hughes Medical Institute investigator. "If a protein misfolds, cells rely on their own recycling system to dispose of it. It turns out that ataxin-3 may influence this system, especially for recycling those that have misfolded due to excessive polyglutamine repeats.. Our findings show that ataxin-3 not only blunts the toxicity of mutant versions of itself but can also mitigate neurodegeneration induced by other such mutant polyglutamine proteins."


Machado-Joseph disease is among the most common dominantly inherited ataxias, a neurodegenerative disorder marked by a gradual decay of muscle control. MJD typically appears in adulthood, with a longer repeat expansion being associated with earlier onset and more severe disease. Its symptoms, uncoordinated motor control, worsen with time.

To study just how the ataxin-3 protein relates to disease, Bonini and her colleagues worked in a simple model organism, the fruit fly, engineering flies to express both the normal human ataxin-3 protein (the protein encoded by the SCA3 gene) and a toxic human disease form of ataxin-3 with an expanded polyglutamine repeat. When both genes are in the same fruit fly, however, the functioning gene helps protect against the effects of the bad one. Their studies surprisingly demonstrated that the protective function of the ataxin-3 protein does not rely on the multiple repeats in its tail but in a region near the head. Indeed, it seems that removing or altering this region of the gene can accelerate the progress of the disease.

"The secret of ataxin-3 is that regions near the start of the protein can counterbalance the toxicity conferred by the excessive polyglutamine repeats in the mutant protein," Bonini said. "In fact, we found evidence that mutant ataxin-3 with the extra-long polyglutamine tail can mitigate its own toxicity."

According to the researchers, it may explain why even normal ataxin-3 can have multiple CAG repeats without causing disease. In other polyglutamine diseases, mutant genes with far fewer repeats can still be toxic, whereas ataxin-3 disease mutations are generally associated with much longer repeats.

"One question now is how this information can be used clinically," Bonini said. "While more research needs to be done, we are hopeful that ataxin-3 may prevent the protein accumulation associated with polyglutamine diseases and perhaps other neurodegenerative situations as well."

Researchers whose work contributed to this study are John M. Warrick (now of the University of Richmond), Lance Morabito, Julide Bilen, Beth Gordesky-Gold and Lynn Faust of Penn, and Henry L. Paulson of the University of Iowa.

Funding for this study was provided by the National Institutes of Health, the David and Lucile Packard Foundation and the Howard Hughes Medical Institute.

Greg Lester | EurekAlert!
Further information:
http://www.upenn.edu

More articles from Life Sciences:

nachricht Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>