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Head: Prof. Danek ELBAUM,
Ph.D. E-mail: elbaum@nencki.gov.pl Staff:
Maria BRZYSKA, Ph.D. Ph.D.
student: Małgorzata PERGOL, M.Sc. |
The main area
of interest is focused on understanding etiology of Alzheimer disease.
More
specifically, we study the mechanism of beta-amyloid
toxicity on the macromolecular
and
cellular level. We are interested
how beta-amyloid induces free radical generation thus
renders the aggregated protein toxic to neurons and other peripheral cells. The
other area of
our
interest is aimed to study Ca(2+)
homeostasis abnormality observed in cells taken from
Alzheimer patients. Two aspects of the research
are exiting to us: (1) understanding the basic mechanisms of the amyloid toxicity, (2) to define the observed differences
between normal and the pathological fibroblasts as a potential diagnostic
marker.
Beta-amyloid peptides are proteolytic
fragments derived from amyloid precursor protein
(APP), a transmembrane glycoprotein. Amyloid
fragments form the core of Alzheimer disease (AD) senile plaques located
predominantly in the cerebral cortex and are implicated as a major determinant
of the pathology. Beta-amyloid formation requires
multiple abnormal hydrolytic events or proteolytic
cleavages of APP. An increasing number of studies show that
oxidative
reactions occur in AD. There is a correlation between areas with elevated
levels of oxidation biomarkers and density of Beta-amylod
cortical deposits. It suggests that Beta-amyloid may
be a molecular link between oxidative stress and AD. Moreover the studies
revealed that Beta-amyloid aggregates induce the
accumulation of hydrogen peroxide in neurons.
Our studies
implicated a novel biochemical property of Beta-amyloid: the ability to cleave
esters
and peptide bonds ( Elbaum, et.al.,
2000, BBRC, 267, 733-738) and more
recently, the propensity to
hydrolyze and oxidize as well ( Brzyska, et.al., 2001, Eur.J. Biochem.,
268, 3443-3454). The results
indicate that the amyloid proteolytic,
hydrolytic and oxidative properties are distinct feature of the peptide and
require different mechanism to occur, but three of them could contribute to its
toxicity. The reported properties could be responsible for early pathogenesis
of AD since there is emerging evidence that the non-plaque amyloid
is elevated in AD patients.
Our
methodology has been confined to determination fluorescence emission and
absorption spectroscopy using several probes capable to report the mechanisms
of the above reactions.
The
sensitivity of the techniques have allowed us to follow small changes using a nano-Molar
concentrations range. The changes of the protein
conformation have been followed with Circular Dichroism. The protein-protein interactions have
been studied using Fluorescence
Resonance
Energy Transfers.
On the
cellular level, we analyzed the operation of K(+) channels in human Alzheimer
donor’s fibroblasts by determination Ca (2+) influx in response to chemically
induced
membrane
depolarization. The results were compared to aged normal and young donors.
Brzyska, et.al.,
2002, Neuro. Res. Comm., 30, 51-61). The results
supported the earlier findings that calcium responses were altered in AD cells.
From a clinical perspective,
especially
the experiments on peripheral cells, such as skin fibroblasts seem to be very
valuable because they offer the possibility of early diagnosis.
Selected
publications:
1. Elbaum,
D., Brzyska, M., Bacia, A.,
Alkon, D. „ Implication of Novel Biochemical
Property of Beta-amyloid”, Biophysical Research
Communication, 267, 733-738, ( 2000)
2. Brzyska,
M., Bacia, A., Elbaum,
D., „ Oxidative and hydrolytic properties of Beta-amyloid”, Eur. J. Biochem., 268, 1-13, ( 2001).
3. Brzyska,M., Michalski,A., Elbaum, D., „ Tetraethylammonium induced changes in intracellular calcium in
Alzheimer donor fibroblasts”, Neuroscience Research Communication,
accepted for
publication, 30, 1, (2002).
4. Chacinska, A., Wozny, W., Boguta, M., Misicka, A., Brzyska, M., Elbaum, D., “ Effect of Beta-Amyloid
on proliferation and morphology of yeast Saccharomyces cerevisiae”
, LIPS, accepted for publication,