P75 neurotrophin receptor regulates expression of neural cell adhesion molecule 1.

Our recent transcriptome profiling studies suggest that presenilin 1 (PS1) regulates expression of neural cell adhesion molecule (Ncam1) through p75 neurotrophin receptor. To better understand regulation of Ncam1 transcript and protein levels by p75, we performed a series of in vitro and in vivo experiments. The combined results suggest that p75 receptor is required for both resting and NGF-induced Ncam1 expression. Activation of TrkA receptors alone does not upregulate Ncam1. The normal Ncam1 expression depends on the relative ratio of TrkA and p75 receptors, and p75 extracellular domain is necessary for baseline Ncam1 expression. NGF-induced Ncam1 expression is dependent on the presence of an intact palmitoylation site within p75 receptor. Finally, we show that the expression of Ncam1 is altered in brains of two transgenic mouse lines that express familial Alzheimer's disease (FAD)-linked PS1 variants, suggesting that expression of dominantly inherited mutant PS1 genes interferes with the normal Ncam1 expression via the p75 signaling pathway.