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P a r t i c i p a n t s :
Luciana Mosca, researcher; Italo Tempera, Alessandra
Masci, post-doc fellows.
C o l l a b o r a t i o n s :
Dipartimento di Farmacologia, Sapienza-Università di Roma (Dr.
Luciano Saso); Université Paris 6 Pierre et Marie Curie, Paris,
France (Prof. Francesco Visioli); Istituto di Biologia e Patologia
Molecolari, CNR, Roma (Dr. Gianni Colotti).
Report of activity
In neurodegenerative diseases such as Alzheimer’s
and Parkinson’s disease, injury might be associated
with altered function of misfolded proteins leading
to the formation of aggregated proteins, the
Amyloid beta and the α-synuclein, respectively.
Amyloid beta peptide (Abeta), a 39-42 residue
polypeptide derived from the proteolytic processing
of the Amyloid precursor protein by secretases, is a
major component of senile plaques and is considered
to have a central role in the pathogenesis of
Alzheimer’s disease.
α-Synuclein can assume various conformations from
monomeric to fibrillar, from unfolded in solution to
alpha-helical in the presence of lipid-containing vesicles,
to a beta-pleated sheet or amyloid structure in
the fibrils that compose the Lewy bodies.
It is well known that both Abeta and α -synuclein can
rapidly undergo fibrillization giving rise to aggregated
forms (Uversky, Curr Alzheimer Res. 2008,
5:260) that is associated to the generation of oxygen
free radicals (Smith et al., BBA 2007, 1768:1976).
Oxidative stress is responsible of DNA damage
which, in turn, is a prime activator of the enzyme
poly(ADP-ribose)polymerase (PARP).
PARP-1 is a zinc-binding nuclear enzyme which catalyzes
the covalent addition of the ADP-ribose moiety
of nicotinamide adenine dinucleotide (NAD + ) to
proteins and the subsequent elongation step of the
41
Molecular genetics of eukaryotes - AREA 3
Epigenetic modifications in neurodegenerative diseases
Principal investigator: Maria d’Erme
Professor of Biochemistry
Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”
Tel: (+39) 06 49910923; Fax: (+39) 06 4440062
maria.derme@uniroma1.it
polymer, which is involved in many physiological
processes such as gene expression, maintenance of
genomic stability and cell death. A causal relationship
between PARP and neurodegeneration is
demonstrated by the findings that parkinsonian neurotoxins
and amyloid-beta potently activate PARP in
dopaminergic neurons and hippocampus, respectively.
In addition, poly(ADP-ribosylated) nuclear proteins
were showed in the neurons of Alzheimer's
patient autopsy brain (Love et al., Brain 1999,
122:247). Further evidence of an involvement of
PARP in neuronal death is based on the finding of
Outerio et al. (BBRC 2007, 357:596) showing that
PARP-1 inhibitors significantly counteract neurotoxicity
in experimental models of neurodegenerative
diseases.
The aim of the present research is to elucidate the
contribution of poly(ADP-ribosylation) process in
neurodegeneration. To achieve this objective, the
dopaminergic neuroblastoma cell line SH-SY5Y was
treated: i) with Abeta 25-35 fragment (Abeta 25-35 ), in
the presence or absence of a new PARP inhibitor, the
4-chinazolinonic derivative MC2050. Abeta 25-35 is
able to preserve all the properties of its full-length
counterparts, in particular the neurotoxicity; ii) with
5-S-cysteinyldopamine (CysDA), or 6-hydroxydopamine
(OH-DA). CysDA has been recently indicated
as a putative endogenous parkinsonian neurotoxin
(Spencer et al., J Neurochem. 2002, 81:122;
Mosca et al., J Neuroscience Res. 2008, 86:954) but its
effects in vivo have not been deeply investigated so far.
CysDA is not commercially available and is routinely
synthesized in our laboratory by a slight modification
of the procedure for 5-S-cysteinyldopa described by
Chioccara and Novellino (Synthetic Commun. 1996,
16:967). OH-DA is a well known parkinsonian neurotoxin
and was used as a positive control.
First objective
We assessed the PARP activity both in vitro and in
cells, in the presence or absence of Abeta25-35 frag-