PARP-1 Modulates Amyloid Beta Peptide-Induced Neuronal Damage

Amyloid beta peptide (Aβ) causes neurodegeneration by several mechanisms including oxidative stress, which is known to induce DNA damage with the consequent activation of poly (ADP-ribose) polymerase (PARP-1). To elucidate the role of PARP-1 in the neurodegenerative process, SH-SY5Y neuroblastoma cells were treated with Aβ_25-35 fragment in the presence or absence of MC2050, a new PARP-1 inhibitor. Aβ_25-35 induces an enhancement of PARP activity which is prevented by cell pre-treatment with MC2050. These data were confirmed by measuring PARP-1 activity in CHO cells transfected with amylod precursor protein and in vivo in brains specimens of TgCRND8 transgenic mice overproducing the amyloid peptide. Following Aβ_25-35 exposure a significant increase in intracellular ROS was observed. These data were supported by the finding that Aβ_25-35 induces DNA damage which in turn activates PARP-1. Challenge with Aβ_25-35 is also able to activate NF-kB via PARP-1, as demonstrated by NF-kB impairment upon MC2050 treatment. Moreover, Aβ_25-35 via PARP-1 induces a significant increase in the p53 protein level and a parallel decrease in the anti-apoptotic Bcl-2 protein. These overall data support the hypothesis of PARP-1 involvment in cellular responses induced by Aβ and hence a possible rationale for the implication of PARP-1 in neurodegeneration is discussed.