The toxic effect of Alzheimer amyloid protein precursor overexpressed in the neuroblastoma cell line NB-1 on neurite outgrowth.

The neuroblastoma cell line NB-1 is induced to start neurite outgrowth by dibutyryl cyclic AMP (Bt2cAMP). To study the function of Alzheimer amyloid protein precursor (APP), a stable cell line overexpressing APP was established by cDNA transfection. The APP cDNA was driven by the cytomegalovirus early gene promoter. The transformant underwent degeneration as well as neurite outgrowth in the presence of Bt2cAMP, which also increased the amount of APP mRNA and protein. The expressed APP was mainly processed in the secretory pathway and few amyloidogenic fragments were observed. Hence, not only the beta/A4 protein but also the overexpressed APP itself might be neurotoxic.