title: Rac1 mediates collapsin-1-induced growth cone collapse.
abstract: Collapsin-1 or semaphorin III(D) inhibits axonal outgrowth by collapsing the lamellipodial and filopodial structures of the neuronal growth cones. Because growth cone collapse is associated with actin depolymerization, we considered whether small GTP-binding proteins of the rho subfamily might participate in collapsin-1 signal transduction. Recombinant rho, rac1, and cdc42 proteins were triturated into embryonic chick (DRG) neurons. Constitutively active rac1 increases the proportion of collapsed growth cones, and dominant negative rac1 inhibits collapsin-1-induced collapse of growth cones and collapsin-1 inhibition of neurite outgrowth. DRG neurons treated with dominant negative rac1 remain sensitive to myelin-induced growth cone collapse. Similar mutants of cdc42 do not alter growth cone structure, neurite elongation, or collapsin-1 sensitivity. Whereas the addition of activated rho has no effect, the inhibition of rho with Clostridium botulinum C3 transferase stimulates the outgrowth of DRG neurites. C3 transferase-treated growth cones exhibit little or no lamellipodial spreading and are minimally responsive to collapsin-1 and myelin. These data demonstrate a prominent role for rho and rac1 in modulating growth cone motility and indicate that rac1 may mediate collapsin-1 action.
authors.affiliation: Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Jin
authors.forename: S M
authors.initials: SM
authors.lastname: Strittmatter
mesh_terms: D036002:ADP Ribose Transferases / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001905:Botulinum Toxins; D018797:Cell Cycle Proteins / Q000378:metabolism; D002478:Cells, Cultured; D002642:Chick Embryo; D019204:GTP-Binding Proteins / Q000378:metabolism*; D005727:Ganglia, Spinal / Q000166:cytology; D006023:Glycoproteins / Q000378:metabolism / Q000494:pharmacology*; D008246:Lysophospholipids / Q000494:pharmacology; D009185:Myelin Proteins / Q000378:metabolism / Q000494:pharmacology; D009414:Nerve Growth Factors / Q000378:metabolism / Q000494:pharmacology; D016501:Neurites / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology; D011994:Recombinant Proteins / Q000494:pharmacology; D040121:Semaphorin-3A; D012680:Sensitivity and Specificity; D013917:Thrombin / Q000494:pharmacology; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins
chemical_list: D018797:Cell Cycle Proteins; D006023:Glycoproteins; D008246:Lysophospholipids; D009185:Myelin Proteins; D009414:Nerve Growth Factors; D011994:Recombinant Proteins; D040121:Semaphorin-3A; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D013917:Thrombin; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins