title: Overexpression of the trk tyrosine kinase rapidly accelerates nerve growth factor-induced differentiation.
abstract: To investigate the role of the gp140trk receptor tyrosine kinase in nerve growth factor (NGF)-induced differentiation, we have overexpressed gp140trk in the NGF-responsive PC12 cell line. Here we demonstrate that overexpression of gp140trk results in marked changes in NGF-induced differentiation. Whereas PC12 cells elaborated neurites after 2 days of continuous exposure to NGF, PC12 cells overexpressing gp140trk by 20-fold(trk-PC12) began this process within hours. Compared with wild-type PC12 cells, trk-PC12 exhibited an increase in both high and low affinity NGF-binding sites. Furthermore, trk-PC12 cells displayed an enhanced level of NGF-dependent gp140trk autophosphorylation, and this activity was sustained for many hours following ligand binding. The tyrosine phosphorylation or activity of several cellular proteins, such as PLC-gamma 1, PI-3 kinase, and Erk1 and the expression of the mRNA for the late response gene transin were also sustained as a consequence of gp140trk overexpression. The data indicate that overexpression of gp140trk in PC12 cells markedly accelerates NGF-induced differentiation pathways, possibly through the elevation of gp140trk tyrosine kinase activity.
authors.affiliation: Cornell University Medical School, Division of Hematology, New York, New York 10021.
authors.forename: B L
authors.initials: BL
authors.lastname: Hempstead
authors.forename: S J
authors.initials: SJ
authors.lastname: Rabin
authors.forename: L
authors.initials: L
authors.lastname: Kaplan
authors.forename: S
authors.initials: S
authors.lastname: Reid
authors.forename: L F
authors.initials: LF
authors.lastname: Parada
authors.forename: D R
authors.initials: DR
authors.lastname: Kaplan
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation / Q000502:physiology*; D015870:Gene Expression; D007163:Immunosorbent Techniques; D007700:Kinetics; D009414:Nerve Growth Factors / Q000494:pharmacology*; D016501:Neurites / Q000502:physiology; D016716:PC12 Cells / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000502:physiology*; D012313:RNA / Q000378:metabolism; D051381:Rats; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor / Q000235:genetics / Q000502:physiology*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D009414:Nerve Growth Factors; D011518:Proto-Oncogene Proteins; D017475:Receptors, Nerve Growth Factor; D019000:Phosphotyrosine; D014443:Tyrosine; D012313:RNA; D020917:Receptor, trkA