Nerve growth factor induces sphingomyelin accumulation in pheochromocytomacells

The pheochromocytoma cells are a well-known model for studying the nerve gr owth factor (NGF)-induced molecular changes during the differentiation proc ess. The involvement of sphingomyelin (SM) was studied using the fluorescen t analogue of ceramide, i.e. N-lissamine rhodaminyl-(12-aminododecanoyl) D- erythro-sphingosine (C12-LRh-Cer). This fluorescent analogue is metabolical ly active and can be used to follow the biosynthesis of SM in intact cells, NGF induces a 4-fold increase of fluorescent SM content in PC12 cells, whe n loaded with C12-LRh-Cer, Treatment of PC12 cells with actinomycin D or cy cloheximide completely abolishes the NGF-induced elevation of SM, Inhibitio n of p140(trkA) receptor by AG-879 prevents extracellular signal-regulated kinase 1/2 phosphorylation and suppresses the increase of SM. Inhibition of protein kinase C (PKC), protein kinase A (PKA) and phosphatidylinositol 3- kinase does not have any effect on NGF-induced C12-LRh-SM accumulation. On the other hand, activation of PKA or PKC with simultaneous treatment with N GF has a synergistic effect on increase of SM content. The NGF-induced SM i ncrease in PC12 cells is an effect promoted by other differentiating agents like dibutyryl cyclic AMP or fibroblast growth factor-2 but not by a mitog enic agent like epidermal growth factor. (C) 2000 Federation of European Bi ochemical Societies.