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  • Title: Nerve growth factor-induced protein kinase C stimulation contributes to TrkA-dependent inhibition of p75 neurotrophin receptor sphingolipid signaling.
    Author: Plo I, Bono F, Bezombes C, Alam A, Bruno A, Laurent G.
    Journal: J Neurosci Res; 2004 Aug 15; 77(4):465-74. PubMed ID: 15264216.
    Abstract:
    Previous studies have established that reciprocal interactions between the low-affinity p75 nerve growth factor (NGF) receptor (p75(NTR)) and the high-affinity TrkA NGF receptor can dictate the cellular response to NGF. As the most important interaction, TrkA signaling was found to inhibit p75(NTR)-mediated sphingomyelinase (SMase) stimulation, ceramide production, and apoptosis. However, the mechanism by which TrkA counteracts p75(NTR)-coupled sphingolipid signaling is still unclear. Considering the stimulatory effect of NGF on protein kinase C (PKC) activity, we investigated the role of PKC in TrkA/p75(NTR) signaling interaction. In this study, we found that, in SK-N-BE cells, which selectively express p75(NTR), phorbol ester-induced PKC stimulation resulted in the abrogation of SMase stimulation and ceramide production induced by NGF. Moreover, in SK-N-BE neuroblastoma cells, which selectively express TrkA, NGF stimulated global PKC activity through two independent pathways involving phospholipase Cgamma (PLCgamma) and phosphoinositide-3 kinase (PI3K). In SH-SY5Y, another neuroblastoma cell line, which coexpresses TrkA and p75(NTR), NGF induced PKC stimulation through a TrkA/PI3K signaling pathway, whereas there was no ceramide production. However, in these cells, the inhibition of TrkA, PI3K, and PKC resulted in the restoration of NGF-induced ceramide production. Thus, our study demonstrates for the first time that TrkA interferes with p75(NTR) signaling through a PI3K/PKC-dependent mechanism.
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