J1/tenascin in substrate-bound and soluble form displays contrary effects on neurite outgrowth.
The influence of J1/tenascin adsorbed to polyornithine-conditioned plastic (substrate-bound J1/tenascin) and J1/tenascin present in the culture medium (soluble J1/tenascin) on neurite outgrowth was studied with cultured single cells from hippocampus and mesencephalon of embryonic rats. Neurons at low density grew well on J1/tenascin substrates and extended neurites that were approximately 40% longer than on the polyornithine control substrate after 24 h in vitro. The neurite outgrowth promoting effect of substrate bound J1/tenascin was largely abolished in the presence of mAb J1/tn2, but not by mAb J1/tn1. In contrast to the neurite growth-promoting effects of substrate bound J1/tenascin, neurite outgrowth on polyornithine, laminin, fibronectin, or J1/tenascin as substrates was inhibited by addition of soluble J1/tenascin to the cultures. Neither of the two mAbs neutralized the neurite outgrowth-inhibitory properties of soluble J1/tenascin. In contrast to their opposite effects on neurite outgrowth, both substrate-bound and soluble J1/tenascin reduced spreading of the neuronal cell bodies, suggesting that the neurite outgrowth-promoting and antispreading effects are mediated by two different sites on the molecule. This was further supported by the inability of the mAb J1/tn2 to neutralize the antispreading effect. The J1/tn2 epitope localizes to a fibronectin type III homology domain that is presumably distinct from the putative Tn68 cell-binding domain of chicken tenascin for fibroblasts, as shown by electronmicroscopic localization of antibody binding sites. We infer from these experiments that J1/tenascin contains a neurite outgrowth promoting domain that is distinguishable from the cell-binding site and presumably not involved in the inhibition of neurite outgrowth or cell spreading. Our observations support the notion that J1/tenascin is a multifunctional extracellular matrix molecule.
Lochter
A
A
Department of Neurobiology, University of Heidelberg, Germany.
Vaughan
L
L
Kaplony
A
A
Prochiantz
A
A
Schachner
M
M
Faissner
A
A
D000818:Animals; D000911:Antibodies, Monoclonal; D001369:Axons / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D001666:Binding Sites, Antibody; D002448:Cell Adhesion / Q000187:drug effects; D015816:Cell Adhesion Molecules, Neuronal / Q000494:pharmacology*; D002478:Cells, Cultured; D004622:Embryo, Mammalian; D000939:Epitopes / Q000032:analysis; D005109:Extracellular Matrix / Q000502:physiology; D016326:Extracellular Matrix Proteins / Q000494:pharmacology*; D006624:Hippocampus / Q000502:physiology* / Q000648:ultrastructure; D007700:Kinetics; D008636:Mesencephalon / Q000502:physiology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D009474:Neurons / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D051381:Rats; D019063:Tenascin
D000911:Antibodies, Monoclonal; D015816:Cell Adhesion Molecules, Neuronal; D000939:Epitopes; D016326:Extracellular Matrix Proteins; D019063:Tenascin