Beginning on page 753, Bui et al. present the first demonstration of ligand-induced tyrosine phosphorylation of IκBα, the well-known inhibitor of the transcription factor NFκB. In NFκB-activating pathways that have been studied previously, the transcription factor is activated by serine phosphorylation and proteasome-mediated degradation of IκBα. Bui et al. propose that the ability to activate NFκB through separate, nonredundant signal transduction pathways might be important in neuronal survival, as well as in inflammation and repair processes.
In the new work, Bui et al. set out to examine the effect of NGF on the expression of the antiapoptotic protein Bcl-xL. In rat PC12 cells, human neuroblastoma SH-SY5Y cells, and primary rat hippocampal neurons, NGF treatment increased NFκB activity and Bcl-xL expression. As expected, overexpressing IκBα in the cells inhibited these NGF-induced effects. However, the NGF-induced NFκB activation was not accompanied...
