January 12, 2016
Fig. 1 - The analysis results for typical Lewy
bodies: The central region (core) contains a large amount of proteins (second
from left) and lipids (fourth from left). In contrast, the content of the β
sheet structure (third from left) is …more
A group of researchers at Osaka University in
cooperation with the Japan Synchrotron Radiation Research Institute (JASRI),
succeeded in elucidating the secondary structure of Lewy bodies in the brain of
Parkinson's disease patients for the first time with synchrotron Fourier
transform infrared micro-spectroscopy
Lewy bodies are considered to be a key element
of pathogenesis for Parkinson's disease. Although structural analysis for Lewy
bodies with an electron microscope had been performed, it had no secondary structural
information of proteins, which is important for the development of drugs.
In recent years, many researchers have focused
on new treatment to inhibit the formation of abnormal protein aggregates, which can
delay the onset and progression of Parkinson's disease. The results and methods
of this research may provide important clues to the development of epoch-making
treatment for Parkinson's disease.
Parkinson's disease is the most common
progressive neurodegenerative disorder after Alzheimer's disease, and there is
no basic treatment to control the development of the disease. It had been known
for quite some time that Lewy bodies, abnormal protein aggregates, are formed
in the brain of Parkinson's disease patients, and it is thought that Lewy
bodies play an important role in the onset of the disease. However, the structural analysis of Lewy bodies has
made no progress other than observation with an electronic microscope in the
last 20 years. Information on proteins required for developing treatment drugs
has been unavailable from electron microscopic observation.
A group of researchers led by Hideki Mochizuki,
Professor and Katsuya Araki, Clinical Fellow at the Department of Neurology,
Graduate School of Medicine, Osaka University, in cooperation with Dr. Naoto
Yagi, JASRI, analyzed proteins by synchrotron Fourier transform infrared
micro-spectroscopy with the infrared beamline BL43IR at the SPring-8
synchrotron radiation facility and succeeded in obtaining structural
information which had not been obtained from the electronic microscopy.
In experiments by this group, it was necessary
to make measurements while irradiating infrared beams of a few micrometers in
diameter on a Lewy body of with a 10 micrometer diameter. For that purpose,
radiation light at the SPring-8, the brightest in the world, played a great
role.
The experiment showed that Lewy bodies in the
brain of Parkinson's disease patients had many β sheet structures. This
supports the validity of in-vitro studies in the past. It was also found that
the rate of β sheet structures was higher in the halo of a Lewy body than in
the core of a Lewy body and the core was lipid-rich. These findings will lead
to the elucidation of the mystery of the formation of Lewy bodies.
This research was featured in the electronic
version of Scientific Reports on Tuesday, December 1, 2015.
β sheet structure
The β sheet structure is one of the typical
secondary structures of proteins and has a stable plane structure due to
hydrogen bonding between a stretch of polypeptide chain and either parallel or
antiparallel extended polypeptide chains. Another typical secondary structure is
α-helix, a spiral conformation.
http://medicalxpress.com/news/2016-01-key-fundamental-treatment-methods-parkinson.html
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