title: Neurotrophin binding to the p75 neurotrophin receptor is necessary but not sufficient to mediate NGF-effects on APP secretion in PC-12 cells.
abstract: In the present study the pheochromocytoma cell line (PC-12) was used as a model system to determine the role of the two neurotrophin receptors in the regulation of amyloid precursor protein (APP) secretion by nerve growth factor (NGF). To stimulate TrkA and/or p75NTR signaling in PC-12 cells, we used NGF, brain-derived neurotrophic factor (BDNF), and NGF in the presence of an excess of BDNF or the monoclonal antibody 192IgG, to block p75NTR binding to NGF. Our results demonstrate that NGF stimulates APP secretion in a dose dependent fashion with maximum effects at 10 ng/ml, known to saturate high-affinity NGF binding sites. Treatment of PC-12 cells with varying concentrations of BDNF, 1-1,000 ng/ml, did not alter APP secretion, suggesting that binding to p75NTR alone is not sufficient to affect APP secretion. When blocking NGF binding to p75NTR with BDNF or 192IgG, on the other hand, NGF effects on APP secretion were abolished. These findings suggest that in cells expressing p75NTR and TrkA receptors, binding of NGF to the p75NTR is required to mediate NGF effects on APP secretion. Our data are also consistent with a proposed function of the p75NTR in receptor recruitment and "presentation" of NGF to receptors.
authors.affiliation: Department of Neurochemistry, Paul Flechsig Institute for Brain Research, Leipzig, Federal Republic of Germany.
authors.forename: S
authors.initials: S
authors.lastname: Rossner
authors.forename: U
authors.initials: U
authors.lastname: Ueberham
authors.forename: R
authors.initials: R
authors.lastname: Schliebs
authors.forename: J R
authors.initials: JR
authors.lastname: Perez-Polo
authors.forename: V
authors.initials: V
authors.lastname: Bigl
mesh_terms: D016564:Amyloid beta-Protein Precursor / Q000096:biosynthesis* / Q000378:metabolism; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007700:Kinetics; D008297:Male; D051379:Mice; D009414:Nerve Growth Factors / Q000378:metabolism / Q000494:pharmacology*; D016716:PC12 Cells; D051381:Rats; D020800:Receptor, Nerve Growth Factor; D017475:Receptors, Nerve Growth Factor / Q000187:drug effects / Q000502:physiology*; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction
chemical_list: D016564:Amyloid beta-Protein Precursor; D000911:Antibodies, Monoclonal; D019208:Brain-Derived Neurotrophic Factor; D009414:Nerve Growth Factors; D020800:Receptor, Nerve Growth Factor; D017475:Receptors, Nerve Growth Factor; D011994:Recombinant Proteins