Activated mutants of the alpha subunit of G(o) promote an increased number of neurites per cell.
The high concentration of the GTP-binding protein G(o) in the neuronal growth cone suggests that G(o) activation state may after neurite outgrowth. We find that activation of pertussis toxin-sensitive G-proteins by mastoparan increases neurite outgrowth from neuroblastoma cells. To examine G(o) activation specifically, point mutations homologous to activating, oncogenic mutations in alpha i2 and alpha s were introduced into the alpha subunit of G(o). The stability of the alpha o mutants to tryptic digestion confirms that they are activated. When expressed in PC12 or N1E-115 cells, activated alpha o doubles total neurites length per cell, primarily by increasing the number of neurites per cell. The growth cones of cells expressing activated alpha o are narrower than control growth cones. Expression of wildtype alpha o or the activated alpha subunits of other G-proteins did not affect total neurite length per cell. Thus, factors that lead to activation of G(o) can modulate neurite number per cell.
Strittmatter
S M
SM
Developmental Biology Laboratory, Massachusetts General Hospital, Charleston.
Fishman
M C
MC
Zhu
X P
XP
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002522:Chlorocebus aethiops; D017931:DNA Primers; D004305:Dose-Response Relationship, Drug; D019204:GTP-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016501:Neurites / Q000187:drug effects / Q000502:physiology*; D009447:Neuroblastoma; D016716:PC12 Cells; D010455:Peptides; D037342:Pertussis Toxin; D017354:Point Mutation; D014162:Transfection; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D014862:Wasp Venoms / Q000494:pharmacology
D017931:DNA Primers; D036341:Intercellular Signaling Peptides and Proteins; D046911:Macromolecular Substances; D010455:Peptides; D010566:Virulence Factors, Bordetella; D014862:Wasp Venoms; C037500:mastoparan; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins