Neurite extension occurs in the absence of regulated exocytosis in PC12 subclones.
We have investigated the process leading to differentiation of PC12 cells. This process is known to include extension of neurites and changes in the expression of subsets of proteins involved in cytoskeletal rearrangements or in neurosecretion. To this aim, we have studied a PC12 clone (trk-PC12) stably transfected with the nerve growth factor receptor TrkA. These cells are able to undergo both spontaneous and neurotrophin-induced morphological differentiation. However, both undifferentiated and nerve growth factor-differentiated trk-PC12 cells appear to be completely defective in the expression of proteins of the secretory apparatus, including proteins of synaptic vesicles and large dense-core granules, neurotransmitter transporters, and neurotransmitter-synthesizing enzymes. These results indicate that neurite extension can occur independently of the presence of the neurosecretory machinery, including the proteins that constitute the fusion machine, suggesting the existence of differential activation pathways for the two processes during neuronal differentiation. These findings have been confirmed in independent clones obtained from PC12-27, a previously characterized PC12 variant clone globally incompetent for regulated secretion. In contrast, the integrity of the Rab cycle appears to be necessary for neurite extension, because antisense oligonucleotides against the neurospecific isoform of Rab-guanosine diphosphate-dissociation inhibitor significantly interfere with process formation.
Leoni
C
C
San Raffaele Scientific Institute, Consiglio Nazionale delle Richerche Center for Cellular and Molecular Pharmacology and B. Ceccarelli Center for Neurobiology, University of Milan, Milan, Italy.
Menegon
A
A
Benfenati
F
F
Toniolo
D
D
Pennuto
M
M
Valtorta
F
F
D000818:Animals; D001905:Botulinum Toxins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D048429:Cell Size / Q000187:drug effects; D002999:Clone Cells; D005089:Exocytosis / Q000502:physiology; D005419:Flavonoids / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D020730:Guanine Nucleotide Dissociation Inhibitors; D006801:Humans; D020929:Mitogen-Activated Protein Kinase Kinases; D009414:Nerve Growth Factors / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000235:genetics; D016501:Neurites / Q000187:drug effects / Q000378:metabolism*; D016716:PC12 Cells; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000502:physiology; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000502:physiology; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor / Q000235:genetics / Q000502:physiology; D013572:Synaptic Vesicles / Q000378:metabolism; D013696:Temperature; D014162:Transfection
D005419:Flavonoids; C086796:GDP dissociation inhibitor 1; D020730:Guanine Nucleotide Dissociation Inhibitors; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D017475:Receptors, Nerve Growth Factor; D011494:Protein Kinases; D020794:Receptor Protein-Tyrosine Kinases; D020917:Receptor, trkA; D020929:Mitogen-Activated Protein Kinase Kinases; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins; C096324:botulinum toxin type C; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one