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 beta 1-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. (c) 2009 Elsevier Inc. All rights reserved.