Poster Presentations

Session Title: Neurodevelopment and Neurodegeneration
Presentation Date: Friday, March 14 – Saturday, March 15, 2009

BETA-AMYLOID INDUCES AN ENHANCEMENT OF PARP ACTIVITY IN A CELLULAR MODEL OF NEURODEGENERATION

L. Mosca¹, I. De Zottis¹, A. Sansone², C. Giordano³, R. Chiaraluce¹, I. Tempera⁴, A. Mai², M. d'Erme^5
1'Sapienza' University, Department of Biochemical Sciences, Roma, Italy, ²'Sapienza' University, Department of Pharmaceutical Studies, Roma, Italy, ³CNR, Institute of Biomolecular Chemistry, Roma, Italy, ⁴Wistar Institute, Philadelphia, United States, ⁵Istituto Pasteur - Fondazione Cenci Bolognetti, Roma, Italy

Amyloid beta (Aβ) peptide causes neurodegeneration and disrupts cognitive function by several mechanisms including oxidative stress, which is known to induce DNA damage and the consequent activation of the enzyme poly(ADP-ribose)polymerase (PARP-1). PARP-1 mediates acute neuronal cell death induced by a variety of insults including cerebral ischemia, parkinsonian neurotoxins and CNS trauma. This study is focused on the contribution of PARP in a cellular model which mimicks Alzheimer's degeneration, i.e. SH-SY5Y neuroblastoma cells treated with Aβ_25-35 fragment, in the presence or absence of a new PARP inhibitor, the chinazolinonic derivative MC2050. The data obtained by PARP activity assay on purified enzyme, indicate that Aβ_25-35 activates PARP around 30-40%. The activation is prevented by the PARP inhibitor. Similar results are obtained when SH-SY5Y cells are treated with Aβ_25-35 which enhances endogenous PARP activity up to 40% within 24 hours of treatment. The increase in PARP activity is prevented by cell pre-treatment with MC2050. In order to verify whether PARP activation is meditated by free radicals, SH-SY5Y cells were treated with Aβ_25-35 or H₂O₂. As shown by flow cytometric analysis, ROS production is markedly increased in cells treated with both agents. This study demonstrate that MC2050 is highly active in the micromolar range (IC₅₀ = 25 µM) compared to the well known inhibitor 3-ABA, and that it is not cytotoxic at the tested concentrations, as revealed by cell viability assay. The regulation of PAR metabolism by specific inhibitors has highlighted the therapeutic potential of PARP inhibitors in human diseases