Chimeric tumor necrosis factor-TrkA receptors reveal that ligand-dependent activation of the TrkA tyrosine kinase is sufficient for differentiation and survival of PC12 cells.
To elucidate the function of the two nerve growth factor (NGF) receptors, p75NGFR and p140trk, chimeric molecules were constructed of tumor necrosis factor (TNF) and NGF receptors. Rat PC12 pheochromocytoma cells transiently transfected with TNF-p140trk chimeras, which contain the extracellular domain of TNF receptor and the transmembrane and cytoplasmic domains of p140trk, showed TNF-dependent neuronal differentiation and cell survival. The activity of TNF-p140trk chimeras was completely blocked by the tyrosine kinase inhibitor K252a, and TNF was unable to induce neurite elongation in PC12 cells transfected with a tyrosine kinase-defective chimeric receptor. The TNF-p75NGFR chimeras, which contain the cytoplasmic domain of p75NGFR, were nonfunctional. Our results suggest that p140trk may function as ligand-activated homodimers and that ligand-mediated activation of the cytoplasmic domain of p140trk alone is sufficient for inducing a neuronal phenotype.
Rovelli
G
G
Department of Neurobiology, Stanford University School of Medicine, CA 94305-5401.
Heller
R A
RA
Canossa
M
M
Shooter
E M
EM
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003001:Cloning, Molecular; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D009414:Nerve Growth Factors / Q000494:pharmacology; D016501:Neurites / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D016716:PC12 Cells; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism*; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D020917:Receptor, trkA; D011956:Receptors, Cell Surface / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D009414:Nerve Growth Factors; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D018124:Receptors, Tumor Necrosis Factor; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D012313:RNA; D011505:Protein-Tyrosine Kinases; D020917:Receptor, trkA