Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers uncover new biological target for combating Parkinson's disease

26.08.2013
Compounds already exist to potentially treat both inherited and non-inherited cases

Researchers at Johns Hopkins and elsewhere have brought new clarity to the picture of what goes awry in the brain during Parkinson's disease and identified a compound that eases the disease's symptoms in mice.


This shows two cells with an excess of the protein AIMP2 (green), which interacts with the enzyme PARP1 (red) in the cells' nuclei.

Credit: Yun-Il Lee/Used with permission from Nature Neuroscience

Their discoveries, described in a paper published online in Nature Neuroscience on August 25, also overturn established ideas about the role of a protein considered key to the disease's progress.

"Not only were we able to identify the mechanism that could cause progressive cell death in both inherited and non-inherited forms of Parkinson's, we found there were already compounds in existence that can cross into the brain and block this from happening," says Valina Dawson, Ph.D., the director of the Stem Cell Biology and Neuroregeneration Programs at the Johns Hopkins University School of Medicine's Institute for Cell Engineering (ICE). "While there are still many things that need to happen before we have a drug for clinical trials, we've taken some very promising first steps."

Dawson and her husband, Ted Dawson, M.D., Ph.D., the director of ICE, have collaborated for decades on studies of the molecular chain of events that leads to Parkinson's. One of their findings was that the function of an enzyme called parkin, which malfunctions in the disease, is to tag a bevy of other proteins for destruction by the cell's recycling machinery. This means that nonfunctional parkin leads to the buildup of its target proteins, and the Dawsons and others are exploring what roles these proteins might play in the disease.

In the new study, the Dawsons collaborated with Debbie Swing and Lino Tessarollo of the National Cancer Institute, to develop mice whose genes for a protein called AIMP2 could be switched into high gear. AIMP2 is one of the proteins normally tagged for destruction by parkin, so the genetically modified mice enabled the research team to put aside the effects of defective parkin and excesses of other proteins and look just at the consequences of too much AIMP2.

The consequences were that the mice developed symptoms similar to those of Parkinson's as they aged, the group found. As in Parkinson's patients, the brain cells that make the chemical dopamine were dying. Since AIMP2 is known for its role in the process of making new proteins, the researchers thought the cell death was caused by problems with this process. But when graduate student Yunjong Lee looked at the efficiency of protein-making in the affected mice, everything appeared normal.

Looking for an alternative explanation, Lee tested how cells with excess AIMP2 responded to compounds blocking various paths to cell death, and found that the AIMP2 was activating a self-destruct pathway called parthanatos, discovered and named by the Dawsons years ago for the for poly(ADP-ribose), or "PAR," and the Greek word thanatos, which means "messenger of death."

The Dawsons had previously seen parthanatos set off after events like traumatic injuries or stroke — not by chronic disease. And there were more surprises to come. Lee found that AIMP2 triggered parthanatos by directly interacting with a protein called PARP1, which was long thought to respond only to DNA damage — not to signals from other proteins. Valina Dawson notes that AIMP2 is actually the second protein found to activate PARP1, but the idea that PARP1 is only involved in detecting and responding to DNA damage is still firmly entrenched in her field.

Since the Dawsons had been studying PARP1 for some time, they knew of compounds drug companies had designed to block this enzyme. Such drugs are already in the process of being tested to protect healthy cells during cancer treatment. Crucially, two of these compounds can cross over the blood-brain barrier that keeps many drugs from affecting brain cells. The research team used a compound that blocks PARP1, and Lee tested it on the mice with too much AIMP2. "Not only did the compound protect dopamine-making neurons from death, it also prevented behavioral abnormalities similar to those seen in Parkinson's disease," Lee says.

Though the results are encouraging, Valina Dawson cautions that there are hurdles that will need to be overcome before either of the brain-accessible compounds has a chance to make it into clinical trials. More extensive animal testing will need to be done, and with mice whose Parkinson's symptoms don't arise from genetically amped-up AIMP2 production. In addition, Dawson explains, in order for trials on any Parkinson's drugs to run effectively, measurable markers of the disease's severity need to be found. Ted Dawson and others at Johns Hopkins say they are now working on a separate project to do just that.

The current study was funded by the National Institute of Neurological Disorders and Stroke (grant number NS38377), the JPB Foundation, and the Intramural Research Program of the National Cancer Institute's Center for Cancer Research. The authors acknowledge the joint participation by the Adrienne Helis Malvin Medical Research Foundation and the Diana Helis Henry Medical Research Foundation, through its direct engagement in the continuous active conduct of medical research in conjunction with The Johns Hopkins Hospital and the Johns Hopkins University School of Medicine and the foundation's Parkinson's disease programs.

Other authors of the study are Senthilkumar S. Karuppagounder, Joo-Ho Shin, Yun-Il Lee, Han Seok Ko, Haisong Jiang, Sung-Ung Kang, Byoung Dae Lee, Ho Chul Kang and Donghoon Kim, all of the Johns Hopkins University School of Medicine.

Related stories:

Johns Hopkins Team Explores Paris; Finds a Key to Parkinson's: http://www.hopkinsmedicine.org/news/media/releases/johns_hopkins_team

_explores_paris_finds_a_key_to_parkinsons_

Parkinson's Disease: Excess of Special Protein Identified As Key to Symptoms and Possible New Target for Treatment with Widely Used Anti-Cancer Drug: http://www.hopkinsmedicine.org/news/media/releases/parkinsons_disease_excess
_of_special_protein_identified_as_key_to_symptoms_and_possible_new_target
_for_treatment_with_widely_used_anti_cancer_drug
The Mouse Model: Less Than Perfect, Still Invaluable: http://www.hopkinsmedicine.org/institute_basic_biomedical_sciences/news_

events/articles_and_stories/model_organisms/201010_mouse_model.html

Shawna Williams | EurekAlert!
Further information:
http://www.jhmi.edu

More articles from Life Sciences:

nachricht What the world's tiniest 'monster truck' reveals
23.08.2017 | American Chemical Society

nachricht Treating arthritis with algae
23.08.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

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

What the world's tiniest 'monster truck' reveals

23.08.2017 | Life Sciences

Treating arthritis with algae

23.08.2017 | Life Sciences

Witnessing turbulent motion in the atmosphere of a distant star

23.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>