title: Nerve growth factor-induced protein kinase C stimulation contributes to TrkA-dependent inhibition of p75 neurotrophin receptor sphingolipid signaling.
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.
authors.affiliation: INSERM U-563, Institut Claudius Regaud, Toulouse, France. plo.isa@wanadoo.fr
authors.forename: I
authors.initials: I
authors.lastname: Plo
authors.forename: F
authors.initials: F
authors.lastname: Bono
authors.forename: C
authors.initials: C
authors.lastname: Bezombes
authors.forename: A
authors.initials: A
authors.lastname: Alam
authors.forename: A
authors.initials: A
authors.lastname: Bruno
authors.forename: G
authors.initials: G
authors.lastname: Laurent
mesh_terms: D045744:Cell Line, Tumor; D002518:Ceramides / Q000378:metabolism; D025461:Feedback, Physiological / Q000502:physiology; D006801:Humans; D020932:Nerve Growth Factor / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000201:enzymology*; D010703:Phorbol Esters / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051966:Phospholipase C gamma; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism*; D020800:Receptor, Nerve Growth Factor; D020917:Receptor, trkA / Q000235:genetics / Q000378:metabolism*; D017475:Receptors, Nerve Growth Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013107:Sphingolipids / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D002518:Ceramides; D010703:Phorbol Esters; D020800:Receptor, Nerve Growth Factor; D017475:Receptors, Nerve Growth Factor; D013107:Sphingolipids; D020932:Nerve Growth Factor; D019869:Phosphatidylinositol 3-Kinases; D020917:Receptor, trkA; D011493:Protein Kinase C; D010738:Type C Phospholipases; D051966:Phospholipase C gamma