Protective role of Bcl-2 on β-amyloid-induced cell death of differentiated PC 12 cells:: reduction of NF-kB and p38 MAP kinase activation

Activation of the apoptosis program by an increased production of beta-amyloid peptides (AP) has been implicated in the neuronal cell death of Alzheimer's disease (AD). Bcl-2 is a well-demonstrated anti-apoptotic protein, however, the mechanisms of anti-apoptotic action of Bcl-2 in Abeta-induced neuronal cell death are not fully understood. In the present study, we therefore have investigated the possibility that overexpression of Bcl-2 may prevent Abeta-induced cell death through inhibition of pro-apoptotic activation of p38 MAP kinase and the transcription factor NF-kappaB in nerve growth factor (NGF)-induced differentiated PC12 cells. Treatment of AP into differentiated PC12 cells transfected with plasmid alone resulted in increase of cell death determined by measurement of cytotoxicity and apoptosis in a dose dependent manner. Consistent with the increase of cell death, treatment of AP resulted in increase of p38 MAP kinase and NF-kappaB activation. However, overexpression of Bcl-2 reduced Abeta-induced apoptosis, and suppressed the activation of p38 MAP kinase and NF-kappaB. In addition, a p38 MAP kinase specific inhibitor SB 203580 attenuated Abeta-induced apoptosis. This inhibitory effect was correlated well with the inhibition of p38 MAP kniase and NF-kappaB activation. Moreover, inhibition of NF-kappaB activation by sodium salicylates reduced Abeta-induced apoptosis and activation of p38 MAP kinase. and up regulated Bcl-2 expression. These results suggest that Bcl-2 overexpression protects against Abeta-induced cell death of differentiated PC 12, and its protective effect may be related to the reduction of Abeta-induced activation of p38 MAP kinase and NF-kappaB. (C) 2004 Elsevier Ireland Ltd and The Japan Neuroscience Society. All rights reserved.