Tenascin-C stimulates contactin-dependent neurite outgrowth via activation of phospholipase C.
Tenascin-C (Tnc) is transiently expressed during neural development. Within its alternatively spliced fibronectin type III (TNfn) -motifs the TNfnD domain is crucial for a neurite outgrowth-promoting region that is recognized by the GPI-linked adhesion molecule of the Ig-superfamily contactin. In order to understand the downstream signaling mechanisms, embryonic day E18 rat hippocampal neurons were cultivated on TNfnBD-containing and control substrates in the presence of various inhibitors. As predicted, axon outgrowth promotion could be suppressed by antibodies to the TNfnD domain, to contactin, or to the beta1-integrin subunit. The chelators BAPTA/AM or EGTA as well as blockade of membrane-based calcium channels or of the release of calcium from intracellular stores reduced axon growth to control levels. The inhibition of phospholipase C and its downstream targets protein kinase C or calmodulin kinase likewise blocked outgrowth promotion. We propose that TNfnBD stimulates the outgrowth of hippocampal neurons by activating calcium- and phospholipase C-depending pathways. Digital video microscopy studies revealed that increase of fiber length was caused by an augmentation of growth cone velocity.
Michele
Melanie
M
Department of Cell Morphology and Molecular Neurobiology, Ruhr-University Bochum, Building ND 05/593, Universitätsstrabetae 150, D-44801 Bochum, Germany.
Faissner
Andreas
A
D000818:Animals; D000831:Animals, Newborn; D000906:Antibodies / Q000494:pharmacology; D018941:Antigens, CD19 / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004622:Embryo, Mammalian; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006624:Hippocampus / Q000166:cytology; D051379:Mice; D009433:Neural Inhibition / Q000187:drug effects; D016501:Neurites / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology* / Q000648:ultrastructure; D009474:Neurons / Q000166:cytology*; D011247:Pregnancy; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011946:Receptors, Antigen / Q000276:immunology; D019063:Tenascin / Q000378:metabolism / Q000494:pharmacology*; D013997:Time Factors; D010738:Type C Phospholipases / Q000378:metabolism*
D000906:Antibodies; D018941:Antigens, CD19; D002147:Calmodulin; D004791:Enzyme Inhibitors; D011946:Receptors, Antigen; D019063:Tenascin; C028641:Tn receptor; D011493:Protein Kinase C; D010738:Type C Phospholipases; D002118:Calcium